COMPOSITIONS AND METHODS FOR EDITING A MUTATION TO PERMIT TRANSCRIPTION OR EXPRESSION

Abstract

The present invention features compositions and methods for editing a gene associated with Shwachman Diamond Syndrome (SDS) using a programmable nucleobase editor, such that the gene is permissive for transcription and generates a functional gene product (e.g., providing a splice site and/or altering a nonsense mutation).

Claims

1. A method of editing a polynucleotide to permit transcription, the method comprising contacting the polynucleotide with a base editor in complex with one or more guide polynucleotides, wherein the base editor comprises a polynucleotide programmable DNA binding domain and a deaminase domain, and wherein one or more of the guide polynucleotides targets the base editor to effect an alteration that introduces a mutation that is permissive for transcription.

2. The method of claim 1, wherein the mutation that is permissive for transcription is a mutation that alters a stop codon, a mutation that introduces a splice acceptor or splice donor site, or a mutation that corrects a splice acceptor or splice donor site.

3. A method of editing a SBDS polynucleotide comprising a mutation associated with Shwachman Diamond Syndrome (SDS), the method comprising contacting the SBDS polynucleotide with a base editor in complex with one or more guide polynucleotides, wherein the base editor comprises a polynucleotide programmable DNA binding domain and a deaminase domain, and wherein one or more of the guide polynucleotides target the base editor to effect an alteration of a mutation associated with Shwachman Diamond Syndrome (SDS).

4. The method of claim 1, wherein the deaminase is a cytidine deaminase or an adenosine deaminase.

5-10. (canceled)

11. The method of claim 3, wherein the base editor is an adenosine base editor (ABE), and wherein one or more of the guide polynucleotides target the base editor to effect an A⋅T to G⋅C alteration of 183-184TA>CT Rs113993991 to generate a missense mutation.

12. The method of claim 4, wherein the guide polynucleotides target one of the following sequences: TABLE-US-00098 TGTAAATGTTTCCTAAGGTC or AATGTTTCCTAAGGTCAGGT.

13. The method of claim 7, wherein the ABE has a 5′-NGC-3′ or 5′-NGG-3′ PAM specificity.

14. The method of claim 11, wherein the base editor is a cytidine base editor, and wherein one or more of the guide polynucleotides target the base editor to effect C⋅G to T⋅A alteration of rs113993993 258+2T>C.

15-18. (canceled)

19. The method of claim 3, wherein the mutation associated with Shwachman Diamond Syndrome (SDS) results from a gene conversion, introduces a stop codon or alters splicing of the gene or encodes an SBDS polypeptide having a truncation.

20-25. (canceled)

26. The method of claim 3, wherein the polynucleotide programmable DNA binding domain comprises a modified SpCas9 or SpCas9 variant having an altered protospacer-adjacent motif (PAM) specificity.

27-44. (canceled)

45. A cell produced by introducing into the cell, or a progenitor thereof: a base editor, a polynucleotide encoding the base editor, to the cell, wherein the base editor comprises a polynucleotide programmable DNA binding domain and a deaminase domain; and one or more guide polynucleotides that target the base editor to effect an alteration associated with aberrant splicing.

46-47. (canceled)

48. The cell of claim 45, wherein the cell is from a subject having Shwachman Diamond Syndrome (SDS).

49-72. (canceled)

73. A method of treating Shwachman Diamond Syndrome (SDS) or a disease associated with aberrant splicing in a subject in need thereof, the method comprising administering to the subject a cell of claim 45.

74-75. (canceled)

76. A method of treating Shwachman Diamond Syndrome (SDS) in a subject, the method comprising: administering to a subject in need thereof: a base editor, or a polynucleotide encoding the base editor, wherein the base editor comprises a polynucleotide programmable DNA binding domain and a deaminase domain; and one or more guide polynucleotides that target the base editor to effect an alteration of a mutation associated with SDS.

77. A method of treating a genetic disease associated with aberrant splicing in a subject, the method comprising: administering to a subject in need thereof: a base editor, or a polynucleotide encoding the base editor, wherein the base editor comprises a polynucleotide programmable DNA binding domain and a deaminase domain; and one or more guide polynucleotides that target the base editor to effect an alteration of a pathogenic mutation that alters splicing.

78-83. (canceled)

84. The method of claim 76, wherein the base editor correction replaces the Lysine (K) at amino acid position 62 with a Tryptophan (W).

85-104. (canceled)

105. A method of producing a cell, or progenitor thereof, the method comprising: (a) introducing into an induced pluripotent stem cell comprising a gene conversion associated with Shwachman Diamond Syndrome (SDS), a base editor, or a polynucleotide encoding the base editor, wherein the base editor comprises a polynucleotide-programmable nucleotide-binding domain and a cytidine deaminase domain or an adenosine deaminase domain; and one or more guide polynucleotides, wherein the one or more guide polynucleotides target the base editor to effect an alteration in a mutation associated with SDS; and (b) differentiating the induced pluripotent stem cell or progenitor into a desired cell type.

106-124. (canceled)

125. A guide RNA comprising a nucleic acid sequence from 5′ to 3′, or a 1, 2, 3, 4, or 5 nucleotide 5′ truncation fragment thereof, selected from one or more of: TABLE-US-00099 GUAAGCAGGCGGGUAACAGC; AGCAGGCGGGUAACAGCUGC; GCGGGUAACAGCUGCAGCAU; UGUAAAUGUUUCCUAAGGUC; AAUGUUUCCUAAGGUCAGGU, GCAGGCGGGUAACAGCUGC, CAGGCGGGUAACAGCUGC, AGGCGGGUAACAGCUGC, and AAGCAGGCGGGUAACAGCUGC.

126. A base editor system for editing a pathogenic mutation in an SBDS gene, wherein the base editor system comprises: (a) a base editor comprising: (i) a polynucleotide-programmable DNA-binding domain, and (ii) a deaminase domain capable of deaminating a polynucleotide present in the SBDS gene conversion or its complement nucleobase; and (b) a guide polynucleotide in conjunction with the polynucleotide-programmable DNA-binding domain, wherein the guide polynucleotide targets the base editor to a target polynucleotide sequence at least a portion of which is located in the SBDS gene, an SBDS pseudo gene, or a reverse complement thereof; wherein deaminating a polynucleotide or its complementary nucleobase permits transcription of the SBDS gene.

127. A base editor system for editing a mutation in a gene that results in aberrant splicing, wherein the base editor system comprises: (a) a base editor comprising: (i) a polynucleotide-programmable DNA-binding domain, and (ii) a deaminase domain capable of deaminating a mutation or its complement nucleobase that results in aberrant splicing; and (b) a guide polynucleotide in conjunction with the polynucleotide-programmable DNA-binding domain, wherein the guide polynucleotide targets the base editor to a target polynucleotide sequence at least a portion of which is located in the gene or its reverse complement; wherein deaminating the mutation or its complement nucleobase permits transcription.

128. A method of editing a pathogenic mutation in a gene that results in aberrant splicing, wherein the method comprises: contacting a target nucleotide sequence, at least a portion of which is located in the gene or its reverse complement, with a base editor comprising: (i) a polynucleotide-programmable DNA-binding domain in conjunction with a guide polynucleotide that targets the base editor to the target polynucleotide sequence, at least a portion of which is located in the gene or its reverse complement, and (ii) a deaminase domain capable of deaminating the pathogenic mutation that results in aberrant splicing or its complement nucleobase; and editing the pathogenic mutation by deaminating the pathogenic mutation or its complement nucleobase upon targeting of the base editor to the target nucleotide sequence, wherein deaminating the pathogenic mutation or its complement nucleobase results in a conversion of the pathogenic mutation to a sequence that permits splicing, thereby correcting the pathogenic mutation.

129-133. (canceled)

134. The method of claim 133, wherein the base editor corrects a splice donor SNP site comprising a mutation in rs113993993 C.fwdarw.T in the SBDS gene.

135. A method of treating SDS in a subject by editing a pathogenic mutation in an SBDS gene, the method comprising: administering a base editor, or a polynucleotide encoding the base editor, to a subject in need thereof, wherein the base editor comprises: (i) a polynucleotide-programmable DNA-binding domain, and (ii) a deaminase domain capable of deaminating a nucleobase within the pathogenic mutation or its complement nucleobase; and administering a guide polynucleotide to the subject, wherein the guide polynucleotide targets the base editor to a target nucleotide sequence at least a portion of which is located in the gene or its reverse complement; and editing the pathogenic mutation in an SBDS geneby deaminating the pathogenic mutation or its complement nucleobase upon targeting of the base editor to the target nucleotide sequence, wherein deaminating the pathogenic mutation or its complement nucleobase permits transcription or corrects the pathogenic mutation.

136. A method of producing a cell, tissue, or organ for treating SDS in a subject in need thereof by correcting a pathogenic mutation in an SBDS gene of the cell, tissue, or organ, the method comprising: contacting the cell, tissue, or organ with a base editor, wherein the base editor comprises: (i) a polynucleotide-programmable DNA-binding domain, and (ii) a deaminase domain capable of deaminating the pathogenic mutation or its complement nucleobase; and contacting the cell, tissue, or organ with a guide polynucleotide, wherein the guide polynucleotide targets the base editor to a target nucleotide sequence at least a portion of which is located in the gene or its reverse complement; and editing the pathogenic mutation by deaminating the mutation or its complement nucleobase upon targeting of the base editor to the target nucleotide sequence, wherein deaminating the pathogenic mutation or its complement nucleobase permits splicing, thereby producing the cell, tissue, or organ for treating SDS.

137-157. (canceled)

158. A method of treating Shwachman Diamond Syndrome (SDS) in a subject in need thereof, the method comprising administering to the subject the cell of claim 45.

159-163. (canceled)

164. A composition comprising a base editor bound to a guide RNA, wherein the guide RNA comprises a nucleic acid sequence that is complementary to an SBDS gene associated with Shwachman Diamond Syndrome (SDS).

165-180. (canceled)

181. A pharmaceutical composition comprising (i) a nucleic acid encoding a base editor; and (ii) the guide RNA of claim 125.

182-185. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0208] FIG. 1A and FIG. 1B show mutations in SBDS that cause SDS. FIG. 1A provides a map of SBDS (coding regions in light shading, non-coding regions in dark shading) and a sequence alignment of the exon 2 region of SBDS and an SBDS protein, with gene-specific (gray; top) and pseudogene-specific (gray; bottom) sequences indicated. Compared with SBDS, SBDSP, which results from the conversion event, exon 2 contains sequence changes that are predicted to result in protein truncation (underlined). These include an in-frame stop codon at position 184 and a T.fwdarw.C change at 250+10 (corresponding to the invariant T of the donor splice site at 258+2 in SBDS) that results in the use of an alternate donor splice site at 250+1 (invariant splice site positions are boxed). FIG. 1B shows sequence reads for cloned segments from the exon 2 region of SBDS indicating sequence changes in individuals with SDS that were derived from gene conversion events between SBDS and its pseudogene; three converted alleles are shown. These include 183-184TA.fwdarw.CT, 258+2T.fwdarw.C and an extended conversion mutation, 183-184TA.fwdarw.CT+201A.fwdarw.G+258+2T.fwdarw.C. In each case, informative flanking positions, including 141 and 258+124, were not converted (green).

[0209] FIGS. 2A-2D are schematic diagrams that illustrate strategies for restoring transcription in an SBDS gene comprising one or more pathogenic mutations. FIG. 2A illustrates a strategy for introducing a mutation that eliminates a stop codon and provides for the expression of an SBDS protein comprising an alternate amino acid (e.g., Trp (W)) at amino acid position 62 (e.g., (K62X)). FIGS. 2B and 2D illustrate a strategy for correcting the splice site at nucleotide position 258 (target SNP rs113993993 C.fwdarw.T). FIG. 2C illustrates the splice donor position at which the canonical splice donor is restored to correct the SNP mutation.

[0210] FIGS. 3A-3C present tables showing the amino acid positions in which substitutions occur in the Cas9 protein, e.g., modified Cas9, such as modified SpCas9, yielding Cas9 variants which have specificity for the altered PAM 5′-NGC-3′ or a PAM containing 5′-NGC-3′, and plasmid constructs encoding the SpCas9 variant sequences. Cytidine base editors (CBEs) which comprise at least one cytidine deaminase and at least one Cas9 variant as described are used with to correct mutations in the SBDS gene associated with SDS as described in Example 3. FIG. 3A presents the amino acid positions that are changed from wildtype in the Cas9 proteins to produce Cas9 variants (designated by the numbers in the left column) that were able to bind an NGC PAM. These Cas9 variants were components of the CBEs assessed in the base editing studies described herein; FIG. 3B presents a subset of the Cas9 variants that provided especially good high on-target editing with limited bystander effects in the studies. Also shown in FIG. 3B is a schematic of Cas9 protein domains and their locations in the Cas9 protein sequence. FIG. 3C illustrates the plasmid vector components encoding the SpCas9 variants, and sequence mutations therein, having specificity for the altered PAM 5′-NGC-3′ as described herein.

[0211] FIG. 4 illustrates a graph comparing the relative mutation rates of base editing achieved by CBEs comprising different cytidine deaminases as shown on the abscissa.

[0212] FIG. 5 is a table showing guide RNAs (gRNAs) that were used with the CBEs assessed in the studies described herein. In embodiments, the gRNA sequences were components of plasmid constructs used in the base editing studies described in the Examples.

[0213] FIGS. 6A-6C show graphs of percent editing (e.g., on-target editing) versus percent bystander edits achieved by NGC CBE variants and the 19mer and 20mer gRNAs, e.g., G88 and G44, as described herein. In the right-hand graph of FIG. 6A, as well as in FIG. 6B, “PV226” and “PV230” refer to the plasmids used in the studies. The PV226 plasmid contains a polynucleotide encoding the Cas9 variant #226, the sequence of which is shown in FIGS. 3A-3C; the PV230 plasmid contains a polynucleotide encoding the Cas9 variant #230, the sequence of which is shown in FIGS. 3A-3C. Percent editing exhibited by other NGC CBEs containing different Cas9 variants, whose sequences are described in FIGS. 3A-3C, and the 20mer gRNA G44 is shown in FIG. 6C.

[0214] FIGS. 7A and 7B show graphs of percent editing by the NGC CBEs comprising the cytidine deaminases and Cas9 variants shown in Table 13 used in conjunction with the 19mer gRNA (G88) and the 20mer gRNA (G44) as described in Example 4 herein.

[0215] FIGS. 8A-8J show graphs of percent base editing (on target and bystander editing) achieved by NGC CBEs comprising different cytidine deaminases and Cas9 (e.g., SpCas9) variant polypeptides having the specific combinations of mutations in the Cas9 amino acid sequence as presented in FIGS. 3A-3C or Table 13, together with either the 19mer or the 20mer gRNAs, as assessed in cell-based (HEK293) assays to correct the splice site SNP in the SBDS polynucleotide sequence. FIG. 8A shows the percent on-target versus bystander editing exhibited by NGC CBE containing the Cas9 variant 225 and PpAPOBEC1 and by the NGC CBEs 454 and 459 (Table 13) containing PpAPOBEC1 and the Cas9 variants 226 and 244 (FIGS. 3A-3C), respectively, used with the 19mer (Guide 88) gRNA. FIG. 8B shows the percent on-target versus bystander editing exhibited by NGC CBE containing the Cas9 variant 225 and PpAPOBEC1 and by the NGC CBEs 454 and 459 (Table 13) containing PpAPOBEC1 and the Cas9 variants 226 and 244, respectively, used with the 20mer (Guide 44) gRNA. FIGS. 8C and 8D show the on-target and bystander base editing percentages of an NGC CBE comprising the AmAPOBEC1 cytidine deaminase and the Cas9 variants 225, 226 and 244 (FIGS. 3A-3C) together with either the 19mer (Guide 88) or the 20mer (Guide 44) gRNA. FIGS. 8E and 8F show the on-target and bystander base editing percentages of an NGC CBE comprising the PmCDA1 cytidine deaminase and the Cas9 variants 225, 453 and 458 (Table 13) together with either the 19mer (Guide 88) or the 20mer (Guide 44) gRNA. FIGS. 8G and 8H show the on-target and bystander base editing percentages of an NGC CBE comprising the RRA3F cytidine deaminase and the Cas9 variants 225, 455 and 460 (Table 13) together with either the 19mer (Guide 88) or the 20mer (Guide 44) gRNA. FIGS. 8I and 8J show the on-target and bystander base editing percentages of an NGC CBE comprising the SsAPOBEC2 cytidine deaminase and the Cas9 variants 225, 456 and 461 (Table 13) together with either the 19mer (Guide 88) or the 20mer (Guide 44) gRNA. In FIGS. 8A-8J, Cas9 variant 225 (or PV225) is alternatively termed “Beam shuffle.

[0216] FIGS. 9A-9D show graphs and dot plots of percent editing by the NGC CBEs comprising PpAPOBEC1 cytidine deaminase polypeptide sequences containing various mutations as described in Example 4, such as an H122A mutation alone and in combination with the amino acid mutations R33A, W90F, K34A, R52A, H121A and Y120F, together with a 19mer gRNA (FIG. 9A) or a 20mer gRNA (FIG. 9B). The percentage of on target versus bystander editing was assessed in in vitro cell-based assays. FIGS. 9C and 9D present the data of FIGS. 9A and 9B, respectively, in dot blot format.

[0217] FIG. 10 presents a table depicting the mutations and combinations of mutations that were made in the SpCas9 protein to create SpCas9 variants having combinations of mutations as shown, including “NRCH” mutations as described by S. Miller et al., April, 2020, “Continuous evolution of SpCas9 variants compatible with non-G PAMs,” Nature Biotechnology, 38(4):471-481 (published online 2020 Feb. 10. doi: 10.1038/s41587-020-0412-8), the contents of which are incorporated by reference herein in their entirety. Combinations of the NRCH mutations (amino acid substitutions) were included in several different SpCas9 variants to determine those that would yield a SpCas9 variant component of the NGC CBEs for use in correcting the splice site SNP in the SBDS gene associated with SDS with high on target versus bystander base editing. (Example 6). In FIG. 10, the amino acids in darker shade reflect amino acid substitutions in the Cas9 (SpCas9) amino acid sequence compared with the sequence of a wild type, nonmutated Cas9 (SpCas9) protein. The amino acids in a lighter shade reflect the amino acid residues of the wild type, nonmutated Cas9 (SpCas9) protein.

[0218] FIGS. 11A and 11B show graphs illustrating percent editing by the NGC CBEs comprising a cytidine deaminase, (e.g., PpAPOBEC1) and SpCas9 variants including one or more NRCH mutations as set forth in FIG. 10 and Example 5, used in conjunction with either the 19mer gRNA or the 20mer gRNA, in cell-based assays to evaluate on target and bystander editing efficiencies of these CBEs to correct the splice site SNP in the SBDS gene associated with SDS. NGC CBEs 468 and 469 (FIG. 10) showed high levels of on-target versus off-target base editing when used in conjunction with either the 19mer or the 20mer gRNA.

[0219] FIGS. 12A-12C show graphs illustrating the results of in vitro cell-based assays carried out to assess base editing efficiency and on-target versus bystander editing percentages of NGC CBEs encoded by mRNA as described in Example 6, together with gRNAs of different lengths (17mer, 18mer, 19mer, 20mer, or 21mer). As observed mRNA 342 with an 18mer and 20mer gRNA had the fewest C to A or C to G transitions compared with mRNA 340 or mRNA 341.

DETAILED DESCRIPTION OF THE INVENTION

[0220] The present invention features compositions and methods that edit a pathogenic genetic mutation that causes aberrant splicing in a gene to permit transcription and achieve a therapeutic effect using a programmable nucleobase editor. In some embodiments, the editing involves converting a stop codon to a codon that is permissive for transcription. In some embodiments, the editing involves providing and correcting a splice acceptor or splice donor site, or providing an alternate splice acceptor or splice donor site. In some embodiments, more than one mutation causing aberrant splicing is corrected.

[0221] The invention is based, at least in part, on a strategy to use adenosine or cytidine base editors (ABEs, CBEs) to edit a pathogenic mutation (e.g., a mutation resulting from gene conversion) in a gene associated with Shwachman Diamond Syndrome (SDS). Accordingly, the invention provides base editor systems comprising an ABE or CBE useful for the treatment or prevention of SDS.

Shwachman Diamond Syndrome (SDS)

[0222] Shwachman Diamond Syndrome (SDS) is an autosomal recessive disorder. Approximately 90% of patients meeting the clinical diagnostic criteria for SDS have mutations in the Shwachman-Bodian-Diamond Syndrome (SBDS) gene. The carrier frequency for this mutation has been estimated at around 1 in 110. This highly conserved gene has five exons encompassing 7.9 kb and maps to the 7q11 centromeric region of chromosome 7. The SDBS gene encodes a novel 250-amino acid protein lacking homology to known protein functional domains. An adjacent pseudogene, SBDSP, shares 97% homology with SBDS but contains deletions and nucleotide changes that prevent the generation of a functional protein. Roughly 75% of patients with SDS have mutations resulting from a gene conversion event with this pseudogene. Gene conversion results when recombination occurs between homologous sequences that are present at different genomic loci (paralogous sequences). The presence of the SBDS pseudo (also termed SBDSP) gene likely resulted from previous gene duplications. The SBDS mRNA and protein are widely expressed throughout human tissues at both the mRNA and protein levels. Although the early truncating SBDS mutation 183 TA>CT is common among patients with SDS, patients homozygous for this mutation have not been identified, suggesting that complete loss of the SBDS expression is likely lethal in human patients.

[0223] Common sequence changes associated with SDS include a TA.fwdarw.CT dinucleotide change at position 183-184 or a deletion of 8 bp at the end of exon 2. Analysis of SBDS genomic sequences confirmed the presence of the 183-184TA.fwdarw.CT change and identified a 258+2T.fwdarw.C change in individuals with SDS expressing the deleted transcript. The mutation 258+2T.fwdarw.C is predicted to disrupt the donor splice site of intron 2, and the 8-bp deletion is consistent with use of an upstream cryptic splice donor site at position 251-252. The dinucleotide alteration 183-184TA.fwdarw.CT introduces an in-frame stop codon (K62X), and 258+2T.fwdarw.C and the resultant 8-bp deletion cause premature truncation of the encoded protein by frameshift (84Cfs3).

[0224] The invention provides compositions and methods that permit transcription of a polynucleotides having one or more alterations (e.g., gene conversions) that result in aberrant splicing, thereby providing for the expression of a functional SBDS protein (e.g., a protein having activity sufficient to ameliorate the effects of SBDS gene conversion). In particular embodiments, the invention provides for the introduction of alterations into an SBDS gene comprising a 183-184TA.fwdarw.CT that converts a TAA stop into TGG, which encodes Trp, and is permissive for transcription. In other embodiments, the invention introduces an alteration in a polynucleotide sequence that introduces a splice donor or effector site that permits splicing of a polynucleotide encoding a protein having biological activity. In some embodiments, the invention corrects a site in Exon 2 of an SBDS gene (e.g., by editing the cytosine at nucleotide position 1495 as shown in FIG. 2B).

Nucleobase Editor

[0225] Disclosed herein is a base editor or a nucleobase editor for editing, modifying or altering a target nucleotide sequence of a polynucleotide. Described herein is a nucleobase editor or a base editor comprising a polynucleotide programmable nucleotide binding domain and a nucleobase editing domain (e.g., adenosine deaminase, cytidine deaminase). A polynucleotide programmable nucleotide binding domain, when in conjunction with a bound guide polynucleotide (e.g., gRNA), can specifically bind to a target polynucleotide sequence (i.e., via complementary base pairing between bases of the bound guide nucleic acid and bases of the target polynucleotide sequence) and thereby localize the base editor to the target nucleic acid sequence desired to be edited. In some embodiments, the target polynucleotide sequence comprises single-stranded DNA or double-stranded DNA. In some embodiments, the target polynucleotide sequence comprises RNA. In some embodiments, the target polynucleotide sequence comprises a DNA-RNA hybrid.

Polynucleotide Programmable Nucleotide Binding Domain

[0226] It should be appreciated that polynucleotide programmable nucleotide binding domains can also include nucleic acid programmable proteins that bind RNA. For example, the polynucleotide programmable nucleotide binding domain can be associated with a nucleic acid that guides the polynucleotide programmable nucleotide binding domain to an RNA. Other nucleic acid programmable DNA binding proteins are also within the scope of this disclosure, though they are not specifically listed in this disclosure.

[0227] A polynucleotide programmable nucleotide binding domain of a base editor can itself comprise one or more domains. For example, a polynucleotide programmable nucleotide binding domain can comprise one or more nuclease domains. In some embodiments, the nuclease domain of a polynucleotide programmable nucleotide binding domain can comprise an endonuclease or an exonuclease. Herein the term “exonuclease” refers to a protein or polypeptide capable of digesting a nucleic acid (e.g., RNA or DNA) from free ends, and the term “endonuclease” refers to a protein or polypeptide capable of catalyzing (e.g., cleaving) internal regions in a nucleic acid (e.g., DNA or RNA). In some embodiments, an endonuclease can cleave a single strand of a double-stranded nucleic acid. In some embodiments, an endonuclease can cleave both strands of a double-stranded nucleic acid molecule. In some embodiments a polynucleotide programmable nucleotide binding domain can be a deoxyribonuclease. In some embodiments a polynucleotide programmable nucleotide binding domain can be a ribonuclease.

[0228] In some embodiments, a nuclease domain of a polynucleotide programmable nucleotide binding domain can cut zero, one, or two strands of a target polynucleotide. In some cases, the polynucleotide programmable nucleotide binding domain can comprise a nickase domain. Herein the term “nickase” refers to a polynucleotide programmable nucleotide binding domain comprising a nuclease domain that is capable of cleaving only one strand of the two strands in a duplexed nucleic acid molecule (e.g., DNA). In some embodiments, a nickase can be derived from a fully catalytically active (e.g., natural) form of a polynucleotide programmable nucleotide binding domain by introducing one or more mutations into the active polynucleotide programmable nucleotide binding domain. For example, where a polynucleotide programmable nucleotide binding domain comprises a nickase domain derived from Cas9, the Cas9-derived nickase domain can include a D10A mutation and a histidine at position 840. In such cases, the residue H840 retains catalytic activity and can thereby cleave a single strand of the nucleic acid duplex. In another example, a Cas9-derived nickase domain can comprise an H840A mutation, while the amino acid residue at position 10 remains a D. In some embodiments, a nickase can be derived from a fully catalytically active (e.g., natural) form of a polynucleotide programmable nucleotide binding domain by removing all or a portion of a nuclease domain that is not required for the nickase activity. For example, where a polynucleotide programmable nucleotide binding domain comprises a nickase domain derived from Cas9, the Cas9-derived nickase domain can comprise a deletion of all or a portion of the RuvC domain or the HNH domain.

[0229] The amino acid sequence of an exemplary catalytically active Cas9 is as follows:

TABLE-US-00015 MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIG ALLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFF HRLEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTD KADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLF EENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALS LGLTPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAK NLSDAILLSDILRVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQL PEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVK LNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIE KILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQS FIERMTNFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAF LSGEQKKAIVDLLFKTNRKVTVKQLKEDYFKKIECFDSVEISGVEDRFN ASLGTYHDLLKIIKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLK TYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSD GFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKK GILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRI EEGIKELGSQILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRL SDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNY WRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEI GKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWMKGR DFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWD PKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEK NPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNE LALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQIS EFSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPAA FKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQLGGD.

[0230] A base editor comprising a polynucleotide programmable nucleotide binding domain comprising a nickase domain is thus able to generate a single-strand DNA break (nick) at a specific polynucleotide target sequence (e.g., determined by the complementary sequence of a bound guide nucleic acid). In some embodiments, the strand of a nucleic acid duplex target polynucleotide sequence that is cleaved by a base editor comprising a nickase domain (e.g., Cas9-derived nickase domain) is the strand that is not edited by the base editor (i.e., the strand that is cleaved by the base editor is opposite to a strand comprising a base to be edited). In other embodiments, a base editor comprising a nickase domain (e.g., Cas9-derived nickase domain) can cleave the strand of a DNA molecule which is being targeted for editing. In such cases, the non-targeted strand is not cleaved.

[0231] Also provided herein are base editors comprising a polynucleotide programmable nucleotide binding domain which is catalytically dead (i.e., incapable of cleaving a target polynucleotide sequence). Herein the terms “catalytically dead” and “nuclease dead” are used interchangeably to refer to a polynucleotide programmable nucleotide binding domain which has one or more mutations and/or deletions resulting in its inability to cleave a strand of a nucleic acid. In some embodiments, a catalytically dead polynucleotide programmable nucleotide binding domain base editor can lack nuclease activity as a result of specific point mutations in one or more nuclease domains. For example, in the case of a base editor comprising a Cas9 domain, the Cas9 can comprise both a D10A mutation and an H840A mutation. Such mutations inactivate both nuclease domains, thereby resulting in the loss of nuclease activity. In other embodiments, a catalytically dead polynucleotide programmable nucleotide binding domain can comprise one or more deletions of all or a portion of a catalytic domain (e.g., RuvC1 and/or HNH domains). In further embodiments, a catalytically dead polynucleotide programmable nucleotide binding domain comprises a point mutation (e.g., D10A or H840A) as well as a deletion of all or a portion of a nuclease domain.

[0232] Also contemplated herein are mutations capable of generating a catalytically dead polynucleotide programmable nucleotide binding domain from a previously functional version of the polynucleotide programmable nucleotide binding domain. For example, in the case of catalytically dead Cas9 (“dCas9”), variants having mutations other than D10A and H840A are provided, which result in nuclease inactivated Cas9. Such mutations, by way of example, include other amino acid substitutions at D10 and H840, or other substitutions within the nuclease domains of Cas9 (e.g., substitutions in the HNH nuclease subdomain and/or the RuvC1 subdomain). Additional suitable nuclease-inactive dCas9 domains can be apparent to those of skill in the art based on this disclosure and knowledge in the field, and are within the scope of this disclosure. Such additional exemplary suitable nuclease-inactive Cas9 domains include, but are not limited to, D10A/H840A, D10A/D839A/H840A, and D10A/D839A/H840A/N863A mutant domains (See, e.g., Prashant et al., CAS9 transcriptional activators for target specificity screening and paired nickases for cooperative genome engineering. Nature Biotechnology. 2013; 31(9): 833-838, the entire contents of which are incorporated herein by reference).

[0233] Non-limiting examples of a polynucleotide programmable nucleotide binding domain which can be incorporated into a base editor include a CRISPR protein-derived domain, a restriction nuclease, a meganuclease, TAL nuclease (TALEN), and a zinc finger nuclease (ZFN). In some cases, a base editor comprises a polynucleotide programmable nucleotide binding domain comprising a natural or modified protein or portion thereof which via a bound guide nucleic acid is capable of binding to a nucleic acid sequence during CRISPR (i.e., Clustered Regularly Interspaced Short Palindromic Repeats)-mediated modification of a nucleic acid. Such a protein is referred to herein as a “CRISPR protein”. Accordingly, disclosed herein is a base editor comprising a polynucleotide programmable nucleotide binding domain comprising all or a portion of a CRISPR protein (i.e. a base editor comprising as a domain all or a portion of a CRISPR protein, also referred to as a “CRISPR protein-derived domain” of the base editor). A CRISPR protein-derived domain incorporated into a base editor can be modified compared to a wild-type or natural version of the CRISPR protein. For example, as described below a CRISPR protein-derived domain can comprise one or more mutations, insertions, deletions, rearrangements and/or recombinations relative to a wild-type or natural version of the CRISPR protein.

[0234] CRISPR is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain spacers, sequences complementary to antecedent mobile elements, and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). In type II CRISPR systems, correct processing of pre-crRNA requires a trans-encoded small RNA (tracrRNA), endogenous ribonuclease 3 (rnc) and a Cas9 protein. The tracrRNA serves as a guide for ribonuclease 3-aided processing of pre-crRNA. Subsequently, Cas9/crRNA/tracrRNA endonucleolytically cleaves linear or circular dsDNA target complementary to the spacer. The target strand not complementary to crRNA is first cut endonucleolytically, and then trimmed 3′-5′ exonucleolytically. In nature, DNA-binding and cleavage typically requires protein and both RNAs. However, single guide RNAs (“sgRNA”, or simply “gNRA”) can be engineered so as to incorporate aspects of both the crRNA and tracrRNA into a single RNA species. See, e.g., Jinek M., Chylinski K., Fonfara I., Hauer M., Doudna J. A., Charpentier E. Science 337:816-821(2012), the entire contents of which is hereby incorporated by reference. Cas9 recognizes a short motif in the CRISPR repeat sequences (the PAM or protospacer adjacent motif) to help distinguish self versus non-self.

[0235] In some embodiments, the methods described herein can utilize an engineered Cas protein. A guide RNA (gRNA) is a short synthetic RNA composed of a scaffold sequence necessary for Cas-binding and a user-defined ˜20 nucleotide spacer that defines the genomic target to be modified. Thus, a skilled artisan can change the genomic or polynucleotide target of the Cas protein by changing the target sequence present in the gRNA. The specificity of the Cas protein is partially determined by how specific the gRNA targeting sequence is for the genomic polynucleotide target sequence compared to the rest of the genome.

[0236] In some embodiments, the gRNA scaffold sequence is as follows:

TABLE-US-00016 GUUUUAGAGC UAGAAAUAGC AAGUUAAAAU AAGGCUAGUC CGUUAUCAAC UUGAAAAAGU GGCACCGAGU CGGUGCUUUU.

[0237] In an embodiment, the RNA scaffold comprises a stem loop. In an embodiment, the RNA scaffold comprises the nucleic acid sequence:

TABLE-US-00017 GUUUUUGUACUCUCAAGAUUUAAGUAACUGUACAACGAAACUUACACAG UUACUUAAAUCUUGCAGAAGCUACAAAGAUAAGGCUUCAUGCCGAAAUC AACACCCUGUCAUUUUAUGGCAGGGUG.

[0238] In an embodiment, the RNA scaffold comprises the nucleic acid sequence:

TABLE-US-00018 GUUUUAGAGCUAGAAAUAGCAAGUUAAAAUAAGGCUAGUCCGUUAUCAA CUUGAAAAAGUGGCACCGAGUCGGUGCUUUU.

[0239] In an embodiment, an S. pyrogenes sgRNA scaffold polynucleotide sequence is as follows:

TABLE-US-00019 GUUUUAGAGCUAGAAAUAGCAAGUUAAAAUAAGGCUAGUCCGUUAUCAA CUUGAAAAAGUGGCACCGAGUCGGUGC.

[0240] In an embodiment, an S. aureus sgRNA scaffold polynucleotide sequence is as follows:

TABLE-US-00020 GUUUUAGUACUCUGUAAUGAAAAUUACAGAAUCUACUAAAACAAGGCAA AAUGCCGUGUUUAUCUCGUCAACUUGUUGGCGAGA.

[0241] In an embodiment, a BhCas12b sgRNA scaffold has the following polynucleotide sequence:

TABLE-US-00021 GUUCUGTCUUUUGGUCAGGACAACCGUCUAGCUAUAAGUGCUGCAGGGUG UGAGAAACUCCUAUUGCUGGACGAUGUCUCUUACGAGGCAUUAGCAC.

[0242] In an embodiment, a BvCas12b sgRNA scaffold has the following polynucleotide sequence:

TABLE-US-00022 GACCUAUAGGGUCAAUGAAUCUGUGCGUGUGCCAUAAGUAAUUAAAAAUU ACCCACCACAGGAGCACCUGAAAACAGGUGCUUGGCAC.

[0243] In some embodiments, a CRISPR protein-derived domain incorporated into a base editor is an endonuclease (e.g., deoxyribonuclease or ribonuclease) capable of binding a target polynucleotide when in conjunction with a bound guide nucleic acid. In some embodiments, a CRISPR protein-derived domain incorporated into a base editor is a nickase capable of binding a target polynucleotide when in conjunction with a bound guide nucleic acid. In some embodiments, a CRISPR protein-derived domain incorporated into a base editor is a catalytically dead domain capable of binding a target polynucleotide when in conjunction with a bound guide nucleic acid. In some embodiments, a target polynucleotide bound by a CRISPR protein derived domain of a base editor is DNA. In some embodiments, a target polynucleotide bound by a CRISPR protein-derived domain of a base editor is RNA.

[0244] Cas proteins that can be used herein include class 1 and class 2 Cas proteins. Non-limiting examples of Cas proteins include Cas1, Cas1B, Cas2, Cas3, Cas4, Cas5, Cas5d, Cas5t, Cas5h, Cas5a, Cash, Cas7, Cas8, Cas9 (also known as Csn1 or Csx12), Cas10, Csy1, Csy2, Csy3, Csy4, Cse1, Cse2, Cse3, Cse4, Cse5e, Csc1, Csc2, Csa5, Csn1, Csn2, Csm1, Csm2, Csm3, Csm4, Csm5, Csm6, Cmr1, Cmr3, Cmr4, Cmr5, Cmr6, Csb1, Csb2, Csb3, Csx17, Csx14, Csx10, Csx16, CsaX, Csx3, Csx1, Csx1S, Csf1, Csf2, CsO, Csf4, Csd1, Csd2, Cst1, Cst2, Csh1, Csh2, Csa1, Csa2, Csa3, Csa4, Csa5, Cas12a/Cpf1, Cas12b/C2c1, Cas12c/C2c3, Cas12d/CasY, Cas12e/CasX, Cas12g, Cas12h, and Cas12i, CARF, DinG, homologues thereof, or modified versions thereof. An unmodified CRISPR enzyme can have DNA cleavage activity, such as Cas9, which has two functional endonuclease domains: RuvC and HNH. A CRISPR enzyme can direct cleavage of one or both strands of a target sequence, such as within a target sequence and/or within a complement of a target sequence. For example, a CRISPR enzyme can direct cleavage of one or both strands within about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 50, 100, 200, 500, or more base pairs from the first or last nucleotide of a target sequence.

[0245] A vector that encodes a CRISPR enzyme that is mutated with respect to a corresponding wild-type enzyme, such that the mutated CRISPR enzyme lacks the ability to cleave one or both strands of a target polynucleotide containing a target sequence, can be used. Cas9 can refer to a polypeptide with at least or at least about 50%, 60%, 70%, 80%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity and/or sequence homology to a wild type exemplary Cas9 polypeptide (e.g., Cas9 from S. pyogenes). Cas9 can refer to a polypeptide with at most or at most about 50%, 60%, 70%, 80%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity and/or sequence homology to a wild type exemplary Cas9 polypeptide (e.g., from S. pyogenes). Cas9 can refer to the wild type or a modified form of the Cas9 protein that can comprise an amino acid change such as a deletion, insertion, substitution, variant, mutation, fusion, chimera, or any combination thereof.

[0246] In some embodiments, a CRISPR protein-derived domain of a base editor can include all or a portion of Cas9 from Corynebacterium ulcerans (NCBI Refs: NC_015683.1, NC_017317.1); Corynebacterium diphtheria (NCBI Refs: NC_016782.1, NC_016786.1); Spiroplasma syrphidicola (NCBI Ref: NC_021284.1); Prevotella intermedia (NCBI Ref: NC_017861.1); Spiroplasma taiwanense (NCBI Ref: NC_021846.1); Streptococcus iniae (NCBI Ref: NC_021314.1); Belliella baltica (NCBI Ref: NC_018010.1); Psychrojlexus torquis (NCBI Ref: NC_018721.1); Streptococcus thermophilus (NCBI Ref: YP_820832.1); Listeria innocua (NCBI Ref: NP472073.1); Campylobacter jejuni (NCBI Ref: YP 002344900.1); Neisseria meningitidis (NCBI Ref: YP 002342100.1), Streptococcus pyogenes, or Staphylococcus aureus.

Cas9 Domains of Nucleobase Editors

[0247] Cas9 nuclease sequences and structures are well known to those of skill in the art (See, e.g., “Complete genome sequence of an M1 strain of Streptococcus pyogenes.” Ferretti et al., J. J., McShan W. M., Ajdic D. J., Savic D. J., Savic G., Lyon K., Primeaux C, Sezate S., Suvorov A. N., Kenton S., Lai H. S., Lin S. P., Qian Y., Jia H. G., Najar F. Z., Ren Q., Zhu H., Song L., White J., Yuan X., Clifton S M., Roe B. A., McLaughlin R. E., Proc. Natl. Acad. Sci. USA. 98:4658-4663(2001); “CRISPR RNA maturation by trans-encoded small RNA and host factor RNase III.” Deltcheva E., Chylinski K., Sharma C. M., Gonzales K., Chao Y., Pirzada Z. A., Eckert M. R., Vogel J., Charpentier E., Nature 471:602-607(2011); and “A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity.” Jinek M., Chylinski K., Fonfara I., Hauer M., Doudna J. A., Charpentier E. Science 337:816-821(2012), the entire contents of each of which are incorporated herein by reference). Cas9 orthologs have been described in various species, including, but not limited to, S. pyogenes and S. thermophilus. Additional suitable Cas9 nucleases and sequences will be apparent to those of skill in the art based on this disclosure, and such Cas9 nucleases and sequences include Cas9 sequences from the organisms and loci disclosed in Chylinski, Rhun, and Charpentier, “The tracrRNA and Cas9 families of type II CRISPR-Cas immunity systems” (2013) RNA Biology 10:5, 726-737; the entire contents of which are incorporated herein by reference.

[0248] In some aspects, a nucleic acid programmable DNA binding protein (napDNAbp) is a Cas9 domain. Non-limiting, exemplary Cas9 domains are provided herein. The Cas9 domain may be a nuclease active Cas9 domain, a nuclease inactive Cas9 domain, or a Cas9 nickase. In some embodiments, the Cas9 domain is a nuclease active domain. For example, the Cas9 domain may be a Cas9 domain that cuts both strands of a duplexed nucleic acid (e.g., both strands of a duplexed DNA molecule). In some embodiments, the Cas9 domain comprises any one of the amino acid sequences as set forth herein. In some embodiments the Cas9 domain comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the amino acid sequences set forth herein. In some embodiments, the Cas9 domain comprises an amino acid sequence that has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 or more mutations compared to any one of the amino acid sequences set forth herein. In some embodiments, the Cas9 domain comprises an amino acid sequence that has at least 10, at least 15, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 500, at least 600, at least 700, at least 800, at least 900, at least 1000, at least 1100, or at least 1200 identical contiguous amino acid residues as compared to any one of the amino acid sequences set forth herein.

[0249] In some embodiments, proteins comprising fragments of Cas9 are provided. For example, in some embodiments, a protein comprises one of two Cas9 domains: (1) the gRNA binding domain of Cas9; or (2) the DNA cleavage domain of Cas9. In some embodiments, proteins comprising Cas9 or fragments thereof are referred to as “Cas9 variants.” A Cas9 variant shares homology to Cas9, or a fragment thereof. For example, a Cas9 variant is at least about 70% identical, at least about 80% identical, at least about 90% identical, at least about 95% identical, at least about 96% identical, at least about 97% identical, at least about 98% identical, at least about 99% identical, at least about 99.5% identical, or at least about 99.9% identical to wild type Cas9. In some embodiments, the Cas9 variant may have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 or more amino acid changes compared to wild type Cas9. In some embodiments, the Cas9 variant comprises a fragment of Cas9 (e.g., a gRNA binding domain or a DNA-cleavage domain), such that the fragment is at least about 70% identical, at least about 80% identical, at least about 90% identical, at least about 95% identical, at least about 96% identical, at least about 97% identical, at least about 98% identical, at least about 99% identical, at least about 99.5% identical, or at least about 99.9% identical to the corresponding fragment of wild type Cas9. In some embodiments, the fragment is at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% identical, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% of the amino acid length of a corresponding wild type Cas9. In some embodiments, the fragment is at least 100 amino acids in length. In some embodiments, the fragment is at least 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, or at least 1300 amino acids in length.

[0250] In some embodiments, Cas9 fusion proteins as provided herein comprise the full-length amino acid sequence of a Cas9 protein, e.g., one of the Cas9 sequences provided herein. In other embodiments, however, fusion proteins as provided herein do not comprise a full-length Cas9 sequence, but comprise only one or more fragments thereof. Exemplary amino acid sequences of suitable Cas9 domains and Cas9 fragments are provided herein, and additional suitable sequences of Cas9 domains and fragments will be apparent to those of skill in the art.

[0251] A Cas9 protein can associate with a guide RNA that guides the Cas9 protein to a specific DNA sequence that has complementary to the guide RNA. In some embodiments, the polynucleotide programmable nucleotide binding domain is a Cas9 domain, for example a nuclease active Cas9, a Cas9 nickase (nCas9), or a nuclease inactive Cas9 (dCas9). Examples of nucleic acid programmable DNA binding proteins include, without limitation, Cas9 (e.g., dCas9 and nCas9), CasX, CasY, Cpf1, Cas12b/C2C1, and Cas12c/C2C3.

[0252] In some embodiments, wild type Cas9 corresponds to Cas9 from Streptococcus pyogenes (NCBI Reference Sequence: NC_017053.1, nucleotide and amino acid sequences as follows).

TABLE-US-00023 ATGGATAAGAAATACTCAATAGGCTTAGATATCGGCACAAATAGCGTCGGATGGGCGGTGAT CACTGATGATTATAAGGTTCCGTCTAAAAAGTTCAAGGTTCTGGGAAATACAGACCGCCACA GTATCAAAAAAAATCTTATAGGGGCTCTTTTATTTGGCAGTGGAGAGACAGCGGAAGCGACT CGTCTCAAACGGACAGCTCGTAGAAGGTATACACGTCGGAAGAATCGTATTTGTTATCTACA GGAGATTTTTTCAAATGAGATGGCGAAAGTAGATGATAGTTTCTTTCATCGACTTGAAGAGT CTTTTTTGGTGGAAGAAGACAAGAAGCATGAACGTCATCCTATTTTTGGAAATATAGTAGAT GAAGTTGCTTATCATGAGAAATATCCAACTATCTATCATCTGCGAAAAAAATTGGCAGATTC TACTGATAAAGCGGATTTGCGCTTAATCTATTTGGCCTTAGCGCATATGATTAAGTTTCGTG GTCATTTTTTGATTGAGGGAGATTTAAATCCTGATAATAGTGATGTGGACAAACTATTTATC CAGTTGGTACAAATCTACAATCAATTATTTGAAGAAAACCCTATTAACGCAAGTAGAGTAGA TGCTAAAGCGATTCTTTCTGCACGATTGAGTAAATCAAGACGATTAGAAAATCTCATTGCTC AGCTCCCCGGTGAGAAGAGAAATGGCTTGTTTGGGAATCTCATTGCTTTGTCATTGGGATTG ACCCCTAATTTTAAATCAAATTTTGATTTGGCAGAAGATGCTAAATTACAGCTTTCAAAAGA TACTTACGATGATGATTTAGATAATTTATTGGCGCAAATTGGAGATCAATATGCTGATTTGT TTTTGGCAGCTAAGAATTTATCAGATGCTATTTTACTTTCAGATATCCTAAGAGTAAATAGT GAAATAACTAAGGCTCCCCTATCAGCTTCAATGATTAAGCGCTACGATGAACATCATCAAGA CTTGACTCTTTTAAAAGCTTTAGTTCGACAACAACTTCCAGAAAAGTATAAAGAAATCTTTT TTGATCAATCAAAAAACGGATATGCAGGTTATATTGATGGGGGAGCTAGCCAAGAAGAATTT TATAAATTTATCAAACCAATTTTAGAAAAAATGGATGGTACTGAGGAATTATTGGTGAAACT AAATCGTGAAGATTTGCTGCGCAAGCAACGGACCTTTGACAACGGCTCTATTCCCCATCAAA TTCACTTGGGTGAGCTGCATGCTATTTTGAGAAGACAAGAAGACTTTTATCCATTTTTAAAA GACAATCGTGAGAAGATTGAAAAAATCTTGACTTTTCGAATTCCTTATTATGTTGGTCCATT GGCGCGTGGCAATAGTCGTTTTGCATGGATGACTCGGAAGTCTGAAGAAACAATTACCCCAT GGAATTTTGAAGAAGTTGTCGATAAAGGTGCTTCAGCTCAATCATTTATTGAACGCATGACA AACTTTGATAAAAATCTTCCAAATGAAAAAGTACTACCAAAACATAGTTTGCTTTATGAGTA TTTTACGGTTTATAACGAATTGACAAAGGTCAAATATGTTACTGAGGGAATGCGAAAACCAG CATTTCTTTCAGGTGAACAGAAGAAAGCCATTGTTGATTTACTCTTCAAAACAAATCGAAAA GTAACCGTTAAGCAATTAAAAGAAGATTATTTCAAAAAAATAGAATGTTTTGATAGTGTTGA AATTTCAGGAGTTGAAGATAGATTTAATGCTTCATTAGGCGCCTACCATGATTTGCTAAAAA TTATTAAAGATAAAGATTTTTTGGATAATGAAGAAAATGAAGATATCTTAGAGGATATTGTT TTAACATTGACCTTATTTGAAGATAGGGGGATGATTGAGGAAAGACTTAAAACATATGCTCA CCTCTTTGATGATAAGGTGATGAAACAGCTTAAACGTCGCCGTTATACTGGTTGGGGACGTT TGTCTCGAAAATTGATTAATGGTATTAGGGATAAGCAATCTGGCAAAACAATATTAGATTTT TTGAAATCAGATGGTTTTGCCAATCGCAATTTTATGCAGCTGATCCATGATGATAGTTTGAC ATTTAAAGAAGATATTCAAAAAGCACAGGTGTCTGGACAAGGCCATAGTTTACATGAACAGA TTGCTAACTTAGCTGGCAGTCCTGCTATTAAAAAAGGTATTTTACAGACTGTAAAAATTGTT GATGAACTGGTCAAAGTAATGGGGCATAAGCCAGAAAATATCGTTATTGAAATGGCACGTGA AAATCAGACAACTCAAAAGGGCCAGAAAAATTCGCGAGAGCGTATGAAACGAATCGAAGAAG GTATCAAAGAATTAGGAAGTCAGATTCTTAAAGAGCATCCTGTTGAAAATACTCAATTGCAA AATGAAAAGCTCTATCTCTATTATCTACAAAATGGAAGAGACATGTATGTGGACCAAGAATT AGATATTAATCGTTTAAGTGATTATGATGTCGATCACATTGTTCCACAAAGTTTCATTAAAG ACGATTCAATAGACAATAAGGTACTAACGCGTTCTGATAAAAATCGTGGTAAATCGGATAAC GTTCCAAGTGAAGAAGTAGTCAAAAAGATGAAAAACTATTGGAGACAACTTCTAAACGCCAA GTTAATCACTCAACGTAAGTTTGATAATTTAACGAAAGCTGAACGTGGAGGTTTGAGTGAAC TTGATAAAGCTGGTTTTATCAAACGCCAATTGGTTGAAACTCGCCAAATCACTAAGCATGTG GCACAAATTTTGGATAGTCGCATGAATACTAAATACGATGAAAATGATAAACTTATTCGAGA GGTTAAAGTGATTACCTTAAAATCTAAATTAGTTTCTGACTTCCGAAAAGATTTCCAATTCT ATAAAGTACGTGAGATTAACAATTACCATCATGCCCATGATGCGTATCTAAATGCCGTCGTT GGAACTGCTTTGATTAAGAAATATCCAAAACTTGAATCGGAGTTTGTCTATGGTGATTATAA AGTTTATGATGTTCGTAAAATGATTGCTAAGTCTGAGCAAGAAATAGGCAAAGCAACCGCAA AATATTTCTTTTACTCTAATATCATGAACTTCTTCAAAACAGAAATTACACTTGCAAATGGA GAGATTCGCAAACGCCCTCTAATCGAAACTAATGGGGAAACTGGAGAAATTGTCTGGGATAA AGGGCGAGATTTTGCCACAGTGCGCAAAGTATTGTCCATGCCCCAAGTCAATATTGTCAAGA AAACAGAAGTACAGACAGGCGGATTCTCCAAGGAGTCAATTTTACCAAAAAGAAATTCGGAC AAGCTTATTGCTCGTAAAAAAGACTGGGATCCAAAAAAATATGGTGGTTTTGATAGTCCAAC GGTAGCTTATTCAGTCCTAGTGGTTGCTAAGGTGGAAAAAGGGAAATCGAAGAAGTTAAAAT CCGTTAAAGAGTTACTAGGGATCACAATTATGGAAAGAAGTTCCTTTGAAAAAAATCCGATT GACTTTTTAGAAGCTAAAGGATATAAGGAAGTTAAAAAAGACTTAATCATTAAACTACCTAA ATATAGTCTTTTTGAGTTAGAAAACGGTCGTAAACGGATGCTGGCTAGTGCCGGAGAATTAC AAAAAGGAAATGAGCTGGCTCTGCCAAGCAAATATGTGAATTTTTTATATTTAGCTAGTCAT TATGAAAAGTTGAAGGGTAGTCCAGAAGATAACGAACAAAAACAATTGTTTGTGGAGCAGCA TAAGCATTATTTAGATGAGATTATTGAGCAAATCAGTGAATTTTCTAAGCGTGTTATTTTAG CAGATGCCAATTTAGATAAAGTTCTTAGTGCATATAACAAACATAGAGACAAACCAATACGT GAACAAGCAGAAAATATTATTCATTTATTTACGTTGACGAATCTTGGAGCTCCCGCTGCTTT TAAATATTTTGATACAACAATTGATCGTAAACGATATACGTCTACAAAAGAAGTTTTAGATG CCACTCTTATCCATCAATCCATCACTGGTCTTTATGAAACACGCATTGATTTGAGTCAGCTA GGAGGTGACTGA MDKKYSIGLDIGTNSVGWAVITDDYKVPSKKFKVLGNTDRHSIKKNLIGALLFGSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLADSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQIYNQLFEENPINASRVDAKAILSARLSKSRRLENLIAQLPGEKRNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNS EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGAYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDRGMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQAGKTILDF LKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGHSLHEQIANLAGSPAIKKGILQTVKIV DELVKVMGHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFIKDDSIDNKVLTRSDKNRGKSDN VPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHV AQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVV GTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANG EIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSD KLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPI DFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASH YEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIR EQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQL GGD
(single underline: HNH domain; double underline: RuvC domain)

[0253] In some embodiments, wild type Cas9 corresponds to, or comprises the following nucleotide and/or amino acid sequences:

TABLE-US-00024 ATGGATAAAAAGTATTCTATTGGTTTAGACATCGGCACTAATTCCGTTGGATGGGCTGTCAT AACCGATGAATACAAAGTACCTTCAAAGAAATTTAAGGTGTTGGGGAACACAGACCGTCATT CGATTAAAAAGAATCTTATCGGTGCCCTCCTATTCGATAGTGGCGAAACGGCAGAGGCGACT CGCCTGAAACGAACCGCTCGGAGAAGGTATACACGTCGCAAGAACCGAATATGTTACTTACA AGAAATTTTTAGCAATGAGATGGCCAAAGTTGACGATTCTTTCTTTCACCGTTTGGAAGAGT CCTTCCTTGTCGAAGAGGACAAGAAACATGAACGGCACCCCATCTTTGGAAACATAGTAGAT GAGGTGGCATATCATGAAAAGTACCCAACGATTTATCACCTCAGAAAAAAGCTAGTTGACTC AACTGATAAAGCGGACCTGAGGTTAATCTACTTGGCTCTTGCCCATATGATAAAGTTCCGTG GGCACTTTCTCATTGAGGGTGATCTAAATCCGGACAACTCGGATGTCGACAAACTGTTCATC CAGTTAGTACAAACCTATAATCAGTTGTTTGAAGAGAACCCTATAAATGCAAGTGGCGTGGA TGCGAAGGCTATTCTTAGCGCCCGCCTCTCTAAATCCCGACGGCTAGAAAACCTGATCGCAC AATTACCCGGAGAGAAGAAAAATGGGTTGTTCGGTAACCTTATAGCGCTCTCACTAGGCCTG ACACCAAATTTTAAGTCGAACTTCGACTTAGCTGAAGATGCCAAATTGCAGCTTAGTAAGGA CACGTACGATGACGATCTCGACAATCTACTGGCACAAATTGGAGATCAGTATGCGGACTTAT TTTTGGCTGCCAAAAACCTTAGCGATGCAATCCTCCTATCTGACATACTGAGAGTTAATACT GAGATTACCAAGGCGCCGTTATCCGCTTCAATGATCAAAAGGTACGATGAACATCACCAAGA CTTGACACTTCTCAAGGCCCTAGTCCGTCAGCAACTGCCTGAGAAATATAAGGAAATATTCT TTGATCAGTCGAAAAACGGGTACGCAGGTTATATTGACGGCGGAGCGAGTCAAGAGGAATTC TACAAGTTTATCAAACCCATATTAGAGAAGATGGATGGGACGGAAGAGTTGCTTGTAAAACT CAATCGCGAAGATCTACTGCGAAAGCAGCGGACTTTCGACAACGGTAGCATTCCACATCAAA TCCACTTAGGCGAATTGCATGCTATACTTAGAAGGCAGGAGGATTTTTATCCGTTCCTCAAA GACAATCGTGAAAAGATTGAGAAAATCCTAACCTTTCGCATACCTTACTATGTGGGACCCCT GGCCCGAGGGAACTCTCGGTTCGCATGGATGACAAGAAAGTCCGAAGAAACGATTACTCCAT GGAATTTTGAGGAAGTTGTCGATAAAGGTGCGTCAGCTCAATCGTTCATCGAGAGGATGACC AACTTTGACAAGAATTTACCGAACGAAAAAGTATTGCCTAAGCACAGTTTACTTTACGAGTA TTTCACAGTGTACAATGAACTCACGAAAGTTAAGTATGTCACTGAGGGCATGCGTAAACCCG CCTTTCTAAGCGGAGAACAGAAGAAAGCAATAGTAGATCTGTTATTCAAGACCAACCGCAAA GTGACAGTTAAGCAATTGAAAGAGGACTACTTTAAGAAAATTGAATGCTTCGATTCTGTCGA GATCTCCGGGGTAGAAGATCGATTTAATGCGTCACTTGGTACGTATCATGACCTCCTAAAGA TAATTAAAGATAAGGACTTCCTGGATAACGAAGAGAATGAAGATATCTTAGAAGATATAGTG TTGACTCTTACCCTCTTTGAAGATCGGGAAATGATTGAGGAAAGACTAAAAACATACGCTCA CCTGTTCGACGATAAGGTTATGAAACAGTTAAAGAGGCGTCGCTATACGGGCTGGGGACGAT TGTCGCGGAAACTTATCAACGGGATAAGAGACAAGCAAAGTGGTAAAACTATTCTCGATTTT CTAAAGAGCGACGGCTTCGCCAATAGGAACTTTATGCAGCTGATCCATGATGACTCTTTAAC CTTCAAAGAGGATATACAAAAGGCACAGGTTTCCGGACAAGGGGACTCATTGCACGAACATA TTGCGAATCTTGCTGGTTCGCCAGCCATCAAAAAGGGCATACTCCAGACAGTCAAAGTAGTG GATGAGCTAGTTAAGGTCATGGGACGTCACAAACCGGAAAACATTGTAATCGAGATGGCACG CGAAAATCAAACGACTCAGAAGGGGCAAAAAAACAGTCGAGAGCGGATGAAGAGAATAGAAG AGGGTATTAAAGAACTGGGCAGCCAGATCTTAAAGGAGCATCCTGTGGAAAATACCCAATTG CAGAACGAGAAACTTTACCTCTATTACCTACAAAATGGAAGGGACATGTATGTTGATCAGGA ACTGGACATAAACCGTTTATCTGATTACGACGTCGATCACATTGTACCCCAATCCTTTTTGA AGGACGATTCAATCGACAATAAAGTGCTTACACGCTCGGATAAGAACCGAGGGAAAAGTGAC AATGTTCCAAGCGAGGAAGTCGTAAAGAAAATGAAGAACTATTGGCGGCAGCTCCTAAATGC GAAACTGATAACGCAAAGAAAGTTCGATAACTTAACTAAAGCTGAGAGGGGTGGCTTGTCTG AACTTGACAAGGCCGGATTTATTAAACGTCAGCTCGTGGAAACCCGCCAAATCACAAAGCAT GTTGCACAGATACTAGATTCCCGAATGAATACGAAATACGACGAGAACGATAAGCTGATTCG GGAAGTCAAAGTAATCACTTTAAAGTCAAAATTGGTGTCGGACTTCAGAAAGGATTTTCAAT TCTATAAAGTTAGGGAGATAAATAACTACCACCATGCGCACGACGCTTATCTTAATGCCGTC GTAGGGACCGCACTCATTAAGAAATACCCGAAGCTAGAAAGTGAGTTTGTGTATGGTGATTA CAAAGTTTATGACGTCCGTAAGATGATCGCGAAAAGCGAACAGGAGATAGGCAAGGCTACAG CCAAATACTTCTTTTATTCTAACATTATGAATTTCTTTAAGACGGAAATCACTCTGGCAAAC GGAGAGATACGCAAACGACCTTTAATTGAAACCAATGGGGAGACAGGTGAAATCGTATGGGA TAAGGGCCGGGACTTCGCGACGGTGAGAAAAGTTTTGTCCATGCCCCAAGTCAACATAGTAA AGAAAACTGAGGTGCAGACCGGAGGGTTTTCAAAGGAATCGATTCTTCCAAAAAGGAATAGT GATAAGCTCATCGCTCGTAAAAAGGACTGGGACCCGAAAAAGTACGGTGGCTTCGATAGCCC TACAGTTGCCTATTCTGTCCTAGTAGTGGCAAAAGTTGAGAAGGGAAAATCCAAGAAACTGA AGTCAGTCAAAGAATTATTGGGGATAACGATTATGGAGCGCTCGTCTTTTGAAAAGAACCCC ATCGACTTCCTTGAGGCGAAAGGTTACAAGGAAGTAAAAAAGGATCTCATAATTAAACTACC AAAGTATAGTCTGTTTGAGTTAGAAAATGGCCGAAAACGGATGTTGGCTAGCGCCGGAGAGC TTCAAAAGGGGAACGAACTCGCACTACCGTCTAAATACGTGAATTTCCTGTATTTAGCGTCC CATTACGAGAAGTTGAAAGGTTCACCTGAAGATAACGAACAGAAGCAACTTTTTGTTGAGCA GCACAAACATTATCTCGACGAAATCATAGAGCAAATTTCGGAATTCAGTAAGAGAGTCATCC TAGCTGATGCCAATCTGGACAAAGTATTAAGCGCATACAACAAGCACAGGGATAAACCCATA CGTGAGCAGGCGGAAAATATTATCCATTTGTTTACTCTTACCAACCTCGGCGCTCCAGCCGC ATTCAAGTATTTTGACACAACGATAGATCGCAAACGATACACTTCTACCAAGGAGGTGCTAG ACGCGACACTGATTCACCAATCCATCACGGGATTATATGAAACTCGGATAGATTTGTCACAG CTTGGGGGTGACGGATCCCCCAAGAAGAAGAGGAAAGTCTCGAGCGACTACAAAGACCATGA CGGTGATTATAAAGATCATGACATCGATTACAAGGATGACGATGACAAGGCTGCAGGA MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD
(single underline: HNH domain; double underline: RuvC domain).

[0254] In some embodiments, wild type Cas9 corresponds to Cas9 from Streptococcus pyogenes (NCBI Reference Sequence: NC_002737.2 (nucleotide sequence as follows); and Uniprot Reference Sequence: Q99ZW2 (amino acid sequence as follows):

TABLE-US-00025 ATGGATAAGAAATACTCAATAGGCTTAGATATCGGCACAAATAGCGTCGGATGGGCGGTGAT CACTGATGAATATAAGGTTCCGTCTAAAAAGTTCAAGGTTCTGGGAAATACAGACCGCCACA GTATCAAAAAAAATCTTATAGGGGCTCTTTTATTTGACAGTGGAGAGACAGCGGAPGCGACT CGTCTCAAACGGACAGCTCGTAGAAGGTATACACGTCGGAAGAATCGTATTTGTTATCTACA GGAGATTTTTTCAAATGAGATGGCGAAAGTAGATGATAGTTTCTTTCATCGACTTGAAGAGT CTTTTTTGGTGGAAGAAGACAAGAAGCATGAACGTCATCCTATTTTTGGAAATATAGTAGAT GAAGTTGCTTATCATGAGAAATATCCAACTATCTATCATCTGCGAAAAAAATTGGTAGATTC TACTGATAAAGCGGATTTGCGCTTAATCTATTTGGCCTTAGCGCATATGATTAAGTTTCGTG GTCATTTTTTGATTGAGGGAGATTTAAATCCTGATAATAGTGATGTGGACAAACTATTTATC CAGTTGGTACAAACCTACAATCAATTATTTGAAGAAAACCCTATTAACGCAAGTGGAGTAGA TGCTAAAGCGATTCTTTCTGCACGATTGAGTAAATCAAGACGATTAGAAAATCTCATTGCTC AGCTCCCCGGTGAGAAGAAAAATGGCTTATTTGGGAATCTCATTGCTTTGTCATTGGGTTTG ACCCCTAATTTTAAATCAAATTTTGATTTGGCAGAAGATGCTAAATTACAGCTTTCAAAAGA TACTTACGATGATGATTTAGATAATTTATTGGCGCAAATTGGAGATCAATATGCTGATTTGT TTTTGGCAGCTAAGAATTTATCAGATGCTATTTTACTTTCAGATATCCTAAGAGTAAATACT GAAATAACTAAGGCTCCCCTATCAGCTTCAATGATTAAACGCTACGATGAACATCATCAAGA CTTGACTCTTTTAAAAGCTTTAGTTCGACAACAACTTCCAGAAAAGTATAAAGAAATCTTTT TTGATCAATCAAAAAACGGATATGCAGGTTATATTGATGGGGGAGCTAGCCAAGAAGAATTT TATAAATTTATCAAACCAATTTTAGAAAAAATGGATGGTACTGAGGAATTATTGGTGAAACT AAATCGTGAAGATTTGCTGCGCAAGCAACGGACCTTTGACAACGGCTCTATTCCCCATCAAA TTCACTTGGGTGAGCTGCATGCTATTTTGAGAAGACAAGAAGACTTTTATCCATTTTTAAAA GACAATCGTGAGAAGATTGAAAAAATCTTGACTTTTCGAATTCCTTATTATGTTGGTCCATT GGCGCGTGGCAATAGTCGTTTTGCATGGATGACTCGGAAGTCTGAAGAAACAATTACCCCAT GGAATTTTGAAGAAGTTGTCGATAAAGGTGCTTCAGCTCAATCATTTATTGAACGCATGACA AACTTTGATAAAAATCTTCCAAATGAAAAAGTACTACCAAAACATAGTTTGCTTTATGAGTA TTTTACGGTTTATAACGAATTGACAAAGGTCAAATATGTTACTGAAGGAATGCGAAAACCAG CATTTCTTTCAGGTGAACAGAAGAAAGCCATTGTTGATTTACTCTTCAAAACAAATCGAAAA GTAACCGTTAAGCAATTAAAAGAAGATTATTTCAAAAAAATAGAATGTTTTGATAGTGTTGA AATTTCAGGAGTTGAAGATAGATTTAATGCTTCATTAGGTACCTACCATGATTTGCTAAAAA TTATTAAAGATAAAGATTTTTTGGATAATGAAGAAAATGAAGATATCTTAGAGGATATTGTT TTAACATTGACCTTATTTGAAGATAGGGAGATGATTGAGGAAAGACTTAAAACATATGCTCA CCTCTTTGATGATAAGGTGATGAAACAGCTTAAACGTCGCCGTTATACTGGTTGGGGACGTT TGTCTCGAAAATTGATTAATGGTATTAGGGATAAGCAATCTGGCAAAACAATATTAGATTTT TTGAAATCAGATGGTTTTGCCAATCGCAATTTTATGCAGCTGATCCATGATGATAGTTTGAC ATTTAAAGAAGACATTCAAAAAGCACAAGTGTCTGGACAAGGCGATAGTTTACATGAACATA TTGCAAATTTAGCTGGTAGCCCTGCTATTAAAAAAGGTATTTTACAGACTGTAAAAGTTGTT GATGAATTGGTCAAAGTAATGGGGCGGCATAAGCCAGAAAATATCGTTATTGAAATGGCACG TGAAAATCAGACAACTCAAAAGGGCCAGAAAAATTCGCGAGAGCGTATGAAACGAATCGAAG AAGGTATCAAAGAATTAGGAAGTCAGATTCTTAAAGAGCATCCTGTTGAAAATACTCAATTG CAAAATGAAAAGCTCTATCTCTATTATCTCCAAAATGGAAGAGACATGTATGTGGACCAAGA ATTAGATATTAATCGTTTAAGTGATTATGATGTCGATCACATTGTTCCACAAAGTTTCCTTA AAGACGATTCAATAGACAATAAGGTCTTAACGCGTTCTGATAAAAATCGTGGTAAATCGGAT AACGTTCCAAGTGAAGAAGTAGTCAAAAAGATGAAAAACTATTGGAGACAACTTCTAAACGC CAAGTTAATCACTCAACGTAAGTTTGATAATTTAACGAAAGCTGAACGTGGAGGTTTGAGTG AACTTGATAAAGCTGGTTTTATCAAACGCCAATTGGTTGAAACTCGCCAAATCACTAAGCAT GTGGCACAAATTTTGGATAGTCGCATGAATACTAAATACGATGAAAATGATAAACTTATTCG AGAGGTTAAAGTGATTACCTTAAAATCTAAATTAGTTTCTGACTTCCGAAAAGATTTCCAAT TCTATAAAGTACGTGAGATTAACAATTACCATCATGCCCATGATGCGTATCTAAATGCCGTC GTTGGAACTGCTTTGATTAAGAAATATCCAAAACTTGAATCGGAGTTTGTCTATGGTGATTA TAAAGTTTATGATGTTCGTAAAATGATTGCTAAGTCTGAGCAAGAAATAGGCAAAGCAACCG CAAAATATTTCTTTTACTCTAATATCATGAACTTCTTCAAAACAGAAATTACACTTGCAAAT GGAGAGATTCGCAAACGCCCTCTAATCGAAACTAATGGGGAAACTGGAGAAATTGTCTGGGA TAAAGGGCGAGATTTTGCCACAGTGCGCAAAGTATTGTCCATGCCCCAAGTCAATATTGTCA AGAAAACAGAAGTACAGACAGGCGGATTCTCCAAGGAGTCAATTTTACCAAAAAGAAATTCG GACAAGCTTATTGCTCGTAAAAAAGACTGGGATCCAAAAAAATATGGTGGTTTTGATAGTCC AACGGTAGCTTATTCAGTCCTAGTGGTTGCTAAGGTGGAAAAAGGGAAATCGAAGAAGTTAA AATCCGTTAAAGAGTTACTAGGGATCACAATTATGGAAAGAAGTTCCTTTGAAAAAAATCCG ATTGACTTTTTAGAAGCTAAAGGATATAAGGAAGTTAAAAAAGACTTAATCATTAAACTACC TAAATATAGTCTTTTTGAGTTAGAAAACGGTCGTAAACGGATGCTGGCTAGTGCCGGAGAAT TACAAAAAGGAAATGAGCTGGCTCTGCCAAGCAAATATGTGAATTTTTTATATTTAGCTAGT CATTATGAAAAGTTGAAGGGTAGTCCAGAAGATAACGAACAAAAACAATTGTTTGTGGAGCA GCATAAGCATTATTTAGATGAGATTATTGAGCAAATCAGTGAATTTTCTAAGCGTGTTATTT TAGCAGATGCCAATTTAGATAAAGTTCTTAGTGCATATAACAAACATAGAGACAAACCAATA CGTGAACAAGCAGAAAATATTATTCATTTATTTACGTTGACGAATCTTGGAGCTCCCGCTGC TTTTAAATATTTTGATACAACAATTGATCGTAAACGATATACGTCTACAAAAGAAGTTTTAG ATGCCACTCTTATCCATCAATCCATCACTGGTCTTTATGAAACACGCATTGATTTGAGTCAG CTAGGAGGTGACTGA MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD (single underline: HNH domain; double underline: RuvC domain)

[0255] In some embodiments, Cas9 refers to Cas9 from: Corynebacterium ulcerans (NCBI Refs: NC_015683.1, NC_017317.1); Corynebacterium diphtheria (NCBI Refs: NC_016782.1, NC_016786.1); Spiroplasma syrphidicola (NCBI Ref: NC_021284.1); Prevotella intermedia (NCBI Ref: NC_017861.1); Spiroplasma taiwanense (NCBI Ref: NC_021846.1); Streptococcus iniae (NCBI Ref: NC_021314.1); Belliella baltica (NCBI Ref: NC_018010.1); Psychrojlexus torquisI (NCBI Ref: NC_018721.1); Streptococcus thermophilus (NCBI Ref: YP_820832.1), Listeria innocua (NCBI Ref: NP_472073.1), Campylobacter jejuni (NCBI Ref: YP_002344900.1) or Neisseria meningitidis (NCBI Ref: YP 002342100.1) or to a Cas9 from any other organism.

[0256] It should be appreciated that additional Cas9 proteins (e.g., a nuclease dead Cas9 (dCas9), a Cas9 nickase (nCas9), or a nuclease active Cas9), including variants and homologs thereof, are within the scope of this disclosure. Exemplary Cas9 proteins include, without limitation, those provided below. In some embodiments, the Cas9 protein is a nuclease dead Cas9 (dCas9). In some embodiments, the Cas9 protein is a Cas9 nickase (nCas9). In some embodiments, the Cas9 protein is a nuclease active Cas9.

[0257] In some embodiments, the Cas9 domain is a nuclease-inactive Cas9 domain (dCas9). For example, the dCas9 domain may bind to a duplexed nucleic acid molecule (e.g., via a gRNA molecule) without cleaving either strand of the duplexed nucleic acid molecule. In some embodiments, the nuclease-inactive dCas9 domain comprises a D10X mutation and a H840X mutation of the amino acid sequence set forth herein, or a corresponding mutation in any of the amino acid sequences provided herein, wherein X is any amino acid change. In some embodiments, the nuclease-inactive dCas9 domain comprises a D10A mutation and a H840A mutation of the amino acid sequence set forth herein, or a corresponding mutation in any of the amino acid sequences provided herein. As one example, a nuclease-inactive Cas9 domain comprises the amino acid sequence set forth in Cloning vector pPlatTET-gRNA2 (Accession No. BAV54124).

[0258] The amino acid sequence of an exemplary catalytically inactive Cas9 (dCas9) is as follows:

TABLE-US-00026 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHR LEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKAD LRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENP INASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTP NFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAI LLSDILRVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEI FFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLR KQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPY YVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDK NLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVD LLFKTNRKVTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKI IKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQ LKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDD SLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKV MGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHP VENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDAIVPQSFLKDD SIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNL TKAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMNTKYDENDKLI REVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVVGTALIKK YPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEI TLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEV QTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVE KGKSKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPK YSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASHYEKLKGSPE DNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDK PIREQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQ SITGLYETRIDLSQLGGD
(see, e.g., Qi et al., “Repurposing CRISPR as an RNA-guided platform for sequence-specific control of gene expression.” Cell. 2013; 152(5):1173-83, the entire contents of which are incorporated herein by reference).

[0259] In some embodiments, a Cas9 nuclease has an inactive (e.g., an inactivated) DNA cleavage domain, that is, the Cas9 is a nickase, referred to as an “nCas9” protein (for “nickase” Cas9). A nuclease-inactivated Cas9 protein may interchangeably be referred to as a “dCas9” protein (for nuclease-“dead” Cas9) or catalytically inactive Cas9. Methods for generating a Cas9 protein (or a fragment thereof) having an inactive DNA cleavage domain are known (See, e.g., Jinek et al., Science. 337:816-821(2012); Qi et al., “Repurposing CRISPR as an RNA-Guided Platform for Sequence-Specific Control of Gene Expression” (2013) Cell. 28; 152(5):1173-83, the entire contents of each of which are incorporated herein by reference). For example, the DNA cleavage domain of Cas9 is known to include two subdomains, the HNH nuclease subdomain and the RuvC1 subdomain. The HNH subdomain cleaves the strand complementary to the gRNA, whereas the RuvC1 subdomain cleaves the non-complementary strand. Mutations within these subdomains can silence the nuclease activity of Cas9. For example, the mutations D10A and H840A completely inactivate the nuclease activity of S. pyogenes Cas9 (Jinek et al., Science. 337:816-821(2012); Qi et al., Cell. 28; 152(5):1173-83 (2013)).

[0260] In some embodiments, the dCas9 domain comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the dCas9 domains provided herein. In some embodiments, the Cas9 domain comprises an amino acid sequences that has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 or more or more mutations compared to any one of the amino acid sequences set forth herein. In some embodiments, the Cas9 domain comprises an amino acid sequence that has at least 10, at least 15, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 500, at least 600, at least 700, at least 800, at least 900, at least 1000, at least 1100, or at least 1200 identical contiguous amino acid residues as compared to any one of the amino acid sequences set forth herein.

[0261] In some embodiments, dCas9 corresponds to, or comprises in part or in whole, a Cas9 amino acid sequence having one or more mutations that inactivate the Cas9 nuclease activity. For example, in some embodiments, a dCas9 domain comprises D10A and an H840A mutation or corresponding mutations in another Cas9.

[0262] In some embodiments, the dCas9 comprises the amino acid sequence of dCas9 (D10A and H840A):

TABLE-US-00027 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHR LEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKAD LRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENP INASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTP NFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAI LLSDILRVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEI FFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLR KQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPY YVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDK NLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVD LLFKTNRKVTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKI IKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQ LKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDD SLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKV MGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHP VENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDAIVPQSFLKDD SIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNL TKAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMNTKYDENDKLI REVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVVGTALIKK YPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEI TLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEV QTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVE KGKSKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPK YSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASHYEKLKGSPE DNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDK PIREQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQ SITGLYETRIDLSQLGGD (single underline: HNH domain; double underline: RuvC domain).

[0263] In some embodiments, the Cas9 domain comprises a D10A mutation, while the residue at position 840 remains a histidine in the amino acid sequence provided above, or at corresponding positions in any of the amino acid sequences provided herein.

[0264] In other embodiments, dCas9 variants having mutations other than D10A and H840A are provided, which, e.g., result in nuclease inactivated Cas9 (dCas9). Such mutations, by way of example, include other amino acid substitutions at D10 and H840, or other substitutions within the nuclease domains of Cas9 (e.g., substitutions in the HNH nuclease subdomain and/or the RuvC1 subdomain). In some embodiments, variants or homologues of dCas9 are provided which are at least about 70% identical, at least about 80% identical, at least about 90% identical, at least about 95% identical, at least about 98% identical, at least about 99% identical, at least about 99.5% identical, or at least about 99.9% identical. In some embodiments, variants of dCas9 are provided having amino acid sequences which are shorter, or longer, by about 5 amino acids, by about 10 amino acids, by about 15 amino acids, by about 20 amino acids, by about 25 amino acids, by about 30 amino acids, by about 40 amino acids, by about 50 amino acids, by about 75 amino acids, by about 100 amino acids or more.

[0265] In some embodiments, the Cas9 domain is a Cas9 nickase. The Cas9 nickase may be a Cas9 protein that is capable of cleaving only one strand of a duplexed nucleic acid molecule (e.g., a duplexed DNA molecule). In some embodiments, the Cas9 nickase cleaves the target strand of a duplexed nucleic acid molecule, meaning that the Cas9 nickase cleaves the strand that is base paired to (complementary to) a gRNA (e.g., an sgRNA) that is bound to the Cas9. In some embodiments, a Cas9 nickase comprises a D10A mutation and has a histidine at position 840. In some embodiments, the Cas9 nickase cleaves the non-target, non-base-edited strand of a duplexed nucleic acid molecule, meaning that the Cas9 nickase cleaves the strand that is not base paired to a gRNA (e.g., an sgRNA) that is bound to the Cas9. In some embodiments, a Cas9 nickase comprises an H840A mutation and has an aspartic acid residue at position 10, or a corresponding mutation. In some embodiments, the Cas9 nickase comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the Cas9 nickases provided herein. Additional suitable Cas9 nickases will be apparent to those of skill in the art based on this disclosure and knowledge in the field, and are within the scope of this disclosure.

[0266] The amino acid sequence of an exemplary catalytically Cas9 nickase (nCas9) is as follows:

TABLE-US-00028 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHR LEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKAD LRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENP INASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTP NFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAI LLSDILRVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEI FFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLR KQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPY YVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDK NLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVD LLFKTNRKVTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKI IKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQ LKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDD SLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKV MGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHP VENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDD SIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNL TKAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMNTKYDENDKLI REVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAVVGTALIKK YPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEI TLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEV QTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVE KGKSKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPK YSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLASHYEKLKGSPE DNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDK PIREQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQ SITGLYETRIDLSQLGGD

[0267] In some embodiments, Cas9 refers to a Cas9 from archaea (e.g., nanoarchaea), which constitute a domain and kingdom of single-celled prokaryotic microbes. In some embodiments, the programmable nucleotide binding protein may be a CasX or CasY protein, which have been described in, for example, Burstein et al., “New CRISPR-Cas systems from uncultivated microbes.” Cell Res. 2017 Feb. 21. doi: 10.1038/cr.2017.21, the entire contents of which is hereby incorporated by reference. Using genome-resolved metagenomics, a number of CRISPR-Cas systems were identified, including the first reported Cas9 in the archaeal domain of life. This divergent Cas9 protein was found in little-studied nanoarchaea as part of an active CRISPR-Cas system. In bacteria, two previously unknown systems were discovered, CRISPR-CasX and CRISPR-CasY, which are among the most compact systems yet discovered. In some embodiments, in a base editor system described herein Cas9 is replaced by CasX, or a variant of CasX. In some embodiments, in a base editor system described herein Cas9 is replaced by CasY, or a variant of CasY. It should be appreciated that other RNA-guided DNA binding proteins may be used as a nucleic acid programmable DNA binding protein (napDNAbp), and are within the scope of this disclosure.

[0268] In some embodiments, the nucleic acid programmable DNA binding protein (napDNAbp) of any of the fusion proteins provided herein may be a CasX or CasY protein. In some embodiments, the napDNAbp is a CasX protein. In some embodiments, the napDNAbp is a CasY protein. In some embodiments, the napDNAbp comprises an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at ease 99.5% identical to a naturally-occurring CasX or CasY protein. In some embodiments, the programmable nucleotide binding protein is a naturally-occurring CasX or CasY protein. In some embodiments, the programmable nucleotide binding protein comprises an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at ease 99.5% identical to any CasX or CasY protein described herein. It should be appreciated that CasX and CasY from other bacterial species may also be used in accordance with the present disclosure.

[0269] An exemplary CasX ((uniprot.org/uniprot/FONN87; uniprot.org/uniprot/FONH53) tr|F0NN87|F0NN87_SULIHCRISPR-associatedCasx protein OS=Sulfolobus islandicus (strain HVE10/4) GN=SiH_0402 PE=4 SV=1) amino acid sequence is as follows:

TABLE-US-00029 MEVPLYNIFGDNYIIQVATEAENSTIYNNKVEIDDEELRNVLNLAYKIAK NNEDAAAERRGKAKKKKGEEGETTTSNIILPLSGNDKNPWTETLKCYNFP TTVALSEVFKNFSQVKECEEVSAPSFVKPEFYEFGRSPGMVERTRRVKLE VEPHYLIIAAAGWVLTRLGKAKVSEGDYVGVNVFTPTRGILYSLIQNVNG IVPGIKPETAFGLWIARKVVSSVTNPNVSVVRIYTISDAVGQNPTTINGG FSIDLTKLLEKRYLLSERLEAIARNALSISSNMRERYIVLANYIYEYLTG SKRLEDLLYFANRDLIMNLNSDDGKVRDLKLISAYVNGELIRGEG.

[0270] An exemplary CasX (>tr|F0NH53|F0NH53_SULIR CRISPR associated protein, Casx OS=Sulfolobus islandicus (strain REY15A) GN=SiRe_0771 PE=4 SV=1) amino acid sequence is as follows:

TABLE-US-00030 MEVPLYNIFGDNYIIQVATEAENSTIYNNKVEIDDEELRNVLNLAYKIAK NNEDAAAERRGKAKKKKGEEGETTTSNIILPLSGNDKNPWTETLKCYNFP TTVALSEVFKNFSQVKECEEVSAPSFVKPEFYKFGRSPGMVERTRRVKLE VEPHYLIMAAAGWVLTRLGKAKVSEGDYVGVNVFTPTRGILYSLIQNVNG IVPGIKPETAFGLWIARKVVSSVTNPNVSVVSIYTISDAVGQNPTTINGG FSIDLTKLLEKRDLLSERLEAIARNALSISSNMRERYIVLANYIYEYLTG SKRLEDLLYFANRDLIMNLNSDDGKVRDLKLISAYVNGELIRGEG. Deltaproteobacteria CasX MEKRINKIRKKLSADNATKPVSRSGPMKTLLVRVMTDDLKKRLEKRRKKP EVMPQVISNNAANNLRMLLDDYTKMKEAILQVYWQEFKDDHVGLMCKFAQ PASKKIDQNKLKPEMDEKGNLTTAGFACSQCGQPLFVYKLEQVSEKGKAY TNYFGRCNVAEHEKLILLAQLKPVKDSDEAVTYSLGKFGQRALDFYSIHV TKESTHPVKPLAQIAGNRYASGPVGKALSDACMGTIASFLSKYQDIIIEH QKVVKGNQKRLESLRELAGKENLEYPSVTLPPQPHTKEGVDfAYNEVIAR VRMWVNLNLWQKLKLSRDDAKPLLRLKGFPSFPVVERRENEVDWWNTINE VKKLIDAKRDMGRVFWSGVTAEKRNTILEGYNYLPNENDHKKREGSLENP KKPAKRQFGDLLLYLEKKYAGDWGKVFDEAWERIDKKIAGLTSHIEREEA RNAEDAQSKAVLTDWLRAKASFVLERLKEMDEKEFYACEIQLQKWYGDLR GNPFAVEAENRVVDISGFSIGSDGHSIQYRNLLAWKYLENGKREFYLLMN YGKKGRIRFTDGTDIKKSGKWQGLLYGGGKAKVIDLTFDPDDEQLIILPL AFGTRQGREFIWNDLLSLETGLIKLANGRVIEKTIYNKKIGRDEPALFVA LTFERREVVDPSNIKPVNLIGVARGENIPAVIALTDPEGCPLPEFKDSSG GPTDILRIGEGYKEKQRAIQAAKEVEQRRAGGYSRKFASKSRNLADDMVR NSARDLFYHAVTHDAVLVFANLSRGFGRQGKRTFMTERQYTKMEDWLTAK LAYEGLTSKTYLSKTLAQYTSKTCSNCGFTITYADMDVMLVRLKKTSDGW ATTLNNKELKAEYQITYYNRYKRQTVEKELSAELDRLSEESGNNDISKWT KGRRDEALFLLKKRFSHRPVQEQFVCLDCGHEVHAAEQAALNIARSWLFL NSNSTEFKSYKSGKQPFVGAWQAFYKRRLKEVWKPNA

[0271] An exemplary CasY ((ncbi.nlm.nih.gov/protein/APG80656.1) >APG80656.1 CRISPR-associated protein CasY [uncultured Parcubacteria group bacterium]) amino acid sequence is as follows:

TABLE-US-00031 MSKRHPRISGVKGYRLHAQRLEYTGKSGAMRTIKYPLYSSPSGGRTVPRE IVSAINDDYVGLYGLSNFDDLYNAEKRNEEKVYSVLDFWYDCVQYGAVFS YTAPGLLKNVAEVRGGSYELTKTLKGSHLYDELQIDKVIKFLNKKEISRA NGSLDKLKKDIIDCFKAEYRERHKDQCNKLADDIKNAKKDAGASLGERQK KLFRDFFGISEQSENDKPSFTNPLNLICCLLPFDTVNNNRNRGEVLFNKL KEYAQKLDKNEGSLEMWEYIGIGNSGTAFSNFLGEGFLGRLRENKITELK KAMMDITDAWRGQEQEEELEKRLRILAALTIKLREPKFDNHWGGYRSDIN GKLSSWLQNYINQTVKIKEDLKGHKKDLKKAKEMINRFGESDTKEEAVVS SLLESIEKIVPDDSADDEKPDIPAIAIYRRFLSDGRLTLNRFVQREDVQE ALIKERLEAEKKKKPKKRKKKSDAEDEKETIDFKELFPHLAKPLKLVPNF YGDSKRELYKKYKNAAIYTDALWKAVEKIYKSAFSSSLKNSFFDTDFDKD FFIKRLQKIFSVYRRFNTDKWKPIVKNSFAPYCDIVSLAENEVLYKPKQS RSRKSAAIDKNRVRLPSTENIAKAGIALARELSVAGFDWKDLLKKEEHEE YIDLIELHKTALALLLAVTETQLDISALDFVENGTVKDFMKTRDGNLVLE GRFLEMFSQSIVFSELRGLAGLMSRKEFITRSAIQTMNGKQAELLYIPHE FQSAKITTPKEMSRAFLDLAPAEFATSLEPESLSEKSLLKLKQMRYYPHY FGYELTRTGQGIDGGVAENALRLEKSPVKKREIKCKQYKTLGRGQNKIVL YVRSSYYQTQFLEWFLHRPKNVQTDVAVSGSFLIDEKKVKTRWNYDALTV ALEPVSGSERVFVSQPFTIFPEKSAEEEGQRYLGIDIGEYGIAYTALEIT GDSAKILDQNFISDPQLKTLREEVKGLKLDQRRGTFAMPSTKIARIRESL VHSLRNRIHHLALKHKAKIVYELEVSRFEEGKQKIKKVYATLKKADVYSE IDADKNLQTTVWGKLAVASEISASYTSQFCGACKKLWRAEMQVDETITTQ ELIGTVRVIKGGILIDAIKDFMRPPIFDENDTPFPKYRDFCDKHHISKKM RGNSCLFICPFCRANADADIQASQTIALLRYVKEEKKVEDYFERFRKLKN IKVLGQMKKI.

[0272] In some embodiments, the nucleic acid programmable DNA binding protein (napDNAbp) is a single effector of a microbial CRISPR-Cas system. Single effectors of microbial CRISPR-Cas systems include, without limitation, Cas9, Cpf1, Cas12b/C2c1, and Cas12c/C2c3. Typically, microbial CRISPR-Cas systems are divided into Class 1 and Class 2 systems. Class 1 systems have multisubunit effector complexes, while Class 2 systems have a single protein effector. For example, Cas9 and Cpf1 are Class 2 effectors. In addition to Cas9 and Cpf1, three distinct Class 2 CRISPR-Cas systems (Cas12b/C2c1, and Cas12c/C2c3) have been described by Shmakov et al., “Discovery and Functional Characterization of Diverse Class 2 CRISPR Cas Systems”, Mol. Cell, 2015 Nov. 5; 60(3): 385-397, the entire contents of which are hereby incorporated by reference. Effectors of two of the systems, Cas12b/C2c1, and Cas12c/C2c3, contain RuvC-like endonuclease domains related to Cpf1. A third system contains an effector with two predicated HEPN RNase domains. Production of mature CRISPR RNA is tracrRNA-independent, unlike production of CRISPR RNA by Cas12b/C2c1. Cas12b/C2c1 depends on both CRISPR RNA and tracrRNA for DNA cleavage.

[0273] The crystal structure of Alicyclobaccillus acidoterrastris Cas12b/C2c1 (AacC2c1) has been reported in complex with a chimeric single-molecule guide RNA (sgRNA). See e.g., Liu et al., “C2c1-sgRNA Complex Structure Reveals RNA-Guided DNA Cleavage Mechanism”, Mol. Cell, 2017 Jan. 19; 65(2):310-322, the entire contents of which are hereby incorporated by reference. The crystal structure has also been reported in Alicyclobacillus acidoterrestris C2c1 bound to target DNAs as ternary complexes. See e.g., Yang et al., “PAM-dependent Target DNA Recognition and Cleavage by C2C1 CRISPR-Cas endonuclease”, Cell, 2016 Dec. 15; 167(7):1814-1828, the entire contents of which are hereby incorporated by reference. Catalytically competent conformations of AacC2c1, both with target and non-target DNA strands, have been captured independently positioned within a single RuvC catalytic pocket, with Cas12b/C2c1-mediated cleavage resulting in a staggered seven-nucleotide break of target DNA. Structural comparisons between Cas12b/C2c1 ternary complexes and previously identified Cas9 and Cpf1 counterparts demonstrate the diversity of mechanisms used by CRISPR-Cas9 systems.

[0274] In some embodiments, the nucleic acid programmable DNA binding protein (napDNAbp) of any of the fusion proteins provided herein may be a Cas12b/C2c1, or a Cas12c/C2c3 protein. In some embodiments, the napDNAbp is a Cas12b/C2c1 protein. In some embodiments, the napDNAbp is a Cas12c/C2c3 protein. In some embodiments, the napDNAbp comprises an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at ease 99.5% identical to a naturally-occurring Cas12b/C2c1 or Cas12c/C2c3 protein. In some embodiments, the napDNAbp is a naturally-occurring Cas12b/C2c1 or Cas12c/C2c3 protein. In some embodiments, the napDNAbp comprises an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at ease 99.5% identical to any one of the napDNAbp sequences provided herein. It should be appreciated that Cas12b/C2c1 or Cas12c/C2c3 from other bacterial species may also be used in accordance with the present disclosure.

[0275] A Cas12b/C2c1 ((uniprot.org/uniprot/T0D7A2 #2) sp|TOD7A2|C2C1_ALIAG CRISPR-associated endonuclease C2c1 OS=Alicyclobacillus acido-terrestris (strain ATCC 49025/DSM 3922/CIP 106132/NCIMB 13137/GD3B) GN=c2c1 PE=1 SV=1) amino acid sequence is as follows:

TABLE-US-00032 MAVKSIKVKLRLDDMPEIRAGLWKLHKEVNAGVRYYTEWLSLLRQENLYR RSPNGDGEQECDKTAEECKAELLERLRARQVENGHRGPAGSDDELLQLAR QLYELLVPQAIGAKGDAQQIARKFLSPLADKDAVGGLGIAKAGNKPRWVR MREAGEPGWEEEKEKAETRKSADRTADVLRALADFGLKPLMRVYTDSEMS SVEWKPLRKGQAVRTWDRDMFQQAIERMMSWESWNQRVGQEYAKLVEQKN RFEQKNFVGQEHLVHLVNQLQQDMKEASPGLESKEQTAHYVTGRALRGSD KVFEKWGKLAPDAPFDLYDAEIKNVQRRNTRRFGSHDLFAKLAEPEYQAL WREDASFLTRYAVYNSILRKLNHAKMFATFTLPDATAHPIWTRFDKLGGN LHQYTFLFNEFGERRHAIRFHKLLKVENGVAREVDDVTVPISMSEQLDNL LPRDPNEPIALYFRDYGAEQHFTGEFGGAKIQCRRDQLAHMHRRRGARDV YLNVSVRVQSQSEARGERRPPYAAVFRLVGDNHRAFVHFDKLSDYLAEHP DDGKLGSEGLLSGLRVMSVDLGLRTSASISVFRVARKDELKPNSKGRVPF FFPIKGNDNLVAVHERSQLLKLPGETESKDLRAIREERQRTLRQLRTQLA YLRLLVRCGSEDVGRRERSWAKLIEQPVDAANHMTPDWREAFENELQKLK SLHGICSDKEWMDAVYESVRRVWRHMGKQVRDWRKDVRSGERPKIRGYAK DVVGGNSIEQIEYLERQYKFLKSWSFFGKVSGQVIRAEKGSRFAITLREH IDHAKEDRLKKLADRIIMEALGYVYALDERGKGKWVAKYPPCQLILLEEL SEYQFNNDRPPSENNQLMQWSHRGVFQELINQAQVHDLLVGTMYAAFSSR FDARTGAPGIRCRRVPARCTQEHNPEPFPWWLNKFVVEHTLDACPLRADD LIPTGEGEIFVSPFSAEEGDFHQIHADLNAAQNLQQRLWSDFDISQIRLR CDWGEVDGELVLIPRLTGKRTADSYSNKVFYTNTGVTYYERERGKKRRKV FAQEKLSEEEAELLVEADEAREKSVVLMRDPSGIINRGNWTRQKEFWSMV NQRIEGYLVKQIRSRVPLQDSACENTGDI.

[0276] BhCas12b (Bacillus hisashii) NCBI Reference Sequence: WP_095142515

TABLE-US-00033 MAPKKKRKVGIHGVPAAATRSFILKIEPNEEVKKGLWKTHEVLNHGIAYY MNILKLIRQEAIYEHHEQDPKNPKKVSKAEIQAELWDFVLKMQKCNSFTH EVDKDEVFNILRELYEELVPSSVEKKGEANQLSNKFLYPLVDPNSQSGKG TASSGRKPRWYNLKIAGDPSWEEEKKKWEEDKKKDPLAKILGKLAEYGLI PLFIPYTDSNEPIVKEIKWMEKSRNQSVRRLDKDMFIQALERFLSWESWN LKVKEEYEKVEKEYKTLEERIKEDIQALKALEQYEKERQEQLLRDTLNTN EYRLSKRGLRGWREIIQKWLKMDENEPSEKYLEVFKDYQRKHPREAGDYS VYEFLSKKENHFIWRNHPEYPYLYATFCEIDKKKKDAKQQATFTLADPIN HPLWVRFEERSGSNLNKYRILTEQLHTEKLKKKLTVQLDRLIYPTESGGW EEKGKVDIVLLPSRQFYNQIFLDIEEKGKHAFTYKDESIKFPLKGTLGGA RVQFDRDHLRRYPHKVESGNVGRIYFNMTVNIEPTESPVSKSLKIHRDDF PKVVNFKPKELTEWIKDSKGKKLKSGIESLEIGLRVMSIDLGQRQAAAAS IFEVVDQKPDIEGKLFFPIKGTELYAVHRASFNIKLPGETLVKSREVLRK AREDNLKLMNQKLNFLRNVLHFQQFEDITEREKRVTKWISRQENSDVPLV YQDELIQIRELMYKPYKDWVAFLKQLHKRLEVEIGKEVKHWRKSLSDGRK GLYGISLKNIDEIDRTRKFLLRWSLRPTEPGEVRRLEPGQRFAIDQLNHL NALKEDRLKKMANTIIMHALGYCYDVRKKKWQAKNPACQIILFEDLSNYN PYEERSRFENSKLMKWSRREIPRQVALQGEIYGLQVGEVGAQFSSRFHAK TGSPGIRCSVVTKEKLQDNRFFKNLQREGRLTLDKIAVLKEGDLYPDKGG EKFISLSKDRKCVITHADINAAQNLQKRFWIRTHGFYKVYCKAYQVDGQT VYIPESKDQKQKIIEEFGEGYFILKDGVYEWVNAGKLKIKKGSSKQSSSE LVDSDILKDSFDLASELKGEKLMLYRDPSGNVFPSDKWMAAGVFFGKLER ILISKLTNQYSISTIEDDSSKQSMKRPAATKKAGQAKKKK

[0277] In some embodiments, the Cas12b is BvCas12B, which is a variant of BhCas12b and comprises the following changes relative to BhCas12B: S893R, K846R, and E837G. BvCas12b (Bacillus sp. V3-13) NCBI Reference Sequence: WP 101661451.1

TABLE-US-00034 MAIRSIKLKMKTNSGTDSIYLRKALWRTHQLINEGIAYYMNLLTLYRQEA IGDKTKEAYQAELINIIRNQQRNNGSSEEHGSDQEILALLRQLYELIIPS SIGESGDANQLGNKFLYPLVDPNSQSGKGTSNAGRKPRWKRLKEEGNPDW ELEKKKDEERKAKDPTVKIFDNLNKYGLLPLFPLFTNIQKDIEWLPLGKR QSVRKWDKDMFIQAIERLLSWESWNRRVADEYKQLKEKTESYYKEHLTGG EEWIEKIRKFEKERNMELEKNAFAPNDGYFITSRQIRGWDRVYEKWSKLP ESASPEELWKVVAEQQNKMSEGFGDPKVFSFLANRENRDIWRGHSERIYH IAAYNGLQKKLSRTKEQATFTLPDAIEHPLWIRYESPGGTNLNLFKLEEK QKKNYYVTLSKIIWPSEEKWIEKENIEIPLAPSIQFNRQIKLKQHVKGKQ EISFSDYSSRISLDGVLGGSRIQFNRKYIKNHKELLGEGDIGPVFFNLVV DVAPLQETRNGRLQSPIGKALKVISSDFSKVIDYKPKELMDWMNTGSASN SFGVASLLEGMRVMSIDMGQRTSASVSIFEVVKELPKDQEQKLFYSINDT ELFAIHKRSFLLNLPGEVVTKNNKQQRQERRKKRQFVRSQIRMLANVLRL ETKKTPDERKKAIHKLMEIVQSYDSWTASQKEVWEKELNLLTNMAAFNDE IWKESLVELHHRIEPYVGQIVSKWRKGLSEGRKNLAGISMWNIDELEDTR RLLISWSKRSRTPGEANRIEIDEPFGSSLLQHIQNVKDDRLKQMANLIIM TALGFKYDKEEKDRYKRWKETYPACQIILFENLNRYLFNLDRSRRENSRL MKWAHRSIPRTVSMQGEMFGLQVGDVRSEYSSRFHAKTGAPGIRCHALTE EDLKAGSNTLKRLIEDGFINESELAYLKKGDIIPSQGGELFVTLSKRYKK DSDNNELTVIHADINAAQNLQKRFWQQNSEVYRVPCQLARMGEDKLYIPK SQTETIKKYFGKGSFVKNNTEQEVYKWEKSEKMKIKTDTTFDLQDLDGFE DISKTIELAQEQQKKYLTMFRDPSGYFFNNETWRPQKEYWSIVNNIIKSC LKKKILSNKVEL

[0278] The Cas9 nuclease has two functional endonuclease domains: RuvC and HNH. Cas9 undergoes a conformational change upon target binding that positions the nuclease domains to cleave opposite strands of the target DNA. The end result of Cas9-mediated DNA cleavage is a double-strand break (DSB) within the target DNA (˜3-4 nucleotides upstream of the PAM sequence). The resulting DSB is then repaired by one of two general repair pathways: (1) the efficient but error-prone non-homologous end joining (NHEJ) pathway; or (2) the less efficient but high-fidelity homology directed repair (HDR) pathway.

[0279] The “efficiency” of non-homologous end joining (NHEJ) and/or homology directed repair (HDR) can be calculated by any convenient method. For example, in some cases, efficiency can be expressed in terms of percentage of successful HDR. For example, a surveyor nuclease assay can be used to generate cleavage products and the ratio of products to substrate can be used to calculate the percentage. For example, a surveyor nuclease enzyme can be used that directly cleaves DNA containing a newly integrated restriction sequence as the result of successful HDR. More cleaved substrate indicates a greater percent HDR (a greater efficiency of HDR). As an illustrative example, a fraction (percentage) of HDR can be calculated using the following equation [(cleavage products)/(substrate plus cleavage products)] (e.g., (b+c)/(a+b+c), where “a” is the band intensity of DNA substrate and “b” and “c” are the cleavage products).

[0280] In some cases, efficiency can be expressed in terms of percentage of successful NHEJ. For example, a T7 endonuclease I assay can be used to generate cleavage products and the ratio of products to substrate can be used to calculate the percentage NHEJ. T7 endonuclease Icleaves mismatched heteroduplex DNA which arises from hybridization of wild-type and mutant DNA strands (NHEJ generates small random insertions or deletions (indels) at the site of the original break). More cleavage indicates a greater percent NHEJ (a greater efficiency of NHEJ). As an illustrative example, a fraction (percentage) of NHEJ can be calculated using the following equation: (1−(1−(b+c)/(a+b+c)).sup.1/2)×100, where “a” is the band intensity of DNA substrate and “b” and “c” are the cleavage products (Ran et. al., Cell. 2013 Sep. 12; 154(6):1380-9; and Ran et al., Nat Protoc. 2013 November; 8(11): 2281-2308).

[0281] The NHEJ repair pathway is the most active repair mechanism, and it frequently causes small nucleotide insertions or deletions (indels) at the DSB site. The randomness of NHEJ-mediated DSB repair has important practical implications, because a population of cells expressing Cas9 and a gRNA or a guide polynucleotide can result in a diverse array of mutations. In most cases, NHEJ gives rise to small indels in the target DNA that result in amino acid deletions, insertions, or frameshift mutations leading to premature stop codons within the open reading frame (ORF) of the targeted gene. The ideal end result is a loss-of-function mutation within the targeted gene.

[0282] While NHEJ-mediated DSB repair often disrupts the open reading frame of the gene, homology directed repair (HDR) can be used to generate specific nucleotide changes ranging from a single nucleotide change to large insertions like the addition of a fluorophore or tag. In order to utilize HDR for gene editing, a DNA repair template containing the desired sequence can be delivered into the cell type of interest with the gRNA(s) and Cas9 or Cas9 nickase. The repair template can contain the desired edit as well as additional homologous sequence immediately upstream and downstream of the target (termed left & right homology arms). The length of each homology arm can be dependent on the size of the change being introduced, with larger insertions requiring longer homology arms. The repair template can be a single-stranded oligonucleotide, double-stranded oligonucleotide, or a double-stranded DNA plasmid. The efficiency of HDR is generally low (<10% of modified alleles) even in cells that express Cas9, gRNA and an exogenous repair template. The efficiency of HDR can be enhanced by synchronizing the cells, since HDR takes place during the S and G2 phases of the cell cycle. Chemically or genetically inhibiting genes involved in NHEJ can also increase HDR frequency.

[0283] In some embodiments, Cas9 is a modified Cas9. A given gRNA targeting sequence can have additional sites throughout the genome where partial homology exists. These sites are called off-targets and need to be considered when designing a gRNA. In addition to optimizing gRNA design, CRISPR specificity can also be increased through modifications to Cas9. Cas9 generates double-strand breaks (DSBs) through the combined activity of two nuclease domains, RuvC and HNH. Cas9 nickase, a D10A mutant of SpCas9, retains one nuclease domain and generates a DNA nick rather than a DSB. The nickase system can also be combined with HDR-mediated gene editing for specific gene edits.

[0284] In some cases, Cas9 is a variant Cas9 protein. A variant Cas9 polypeptide has an amino acid sequence that is different by one amino acid (e.g., has a deletion, insertion, substitution, fusion) when compared to the amino acid sequence of a wild type Cas9 protein. In some instances, the variant Cas9 polypeptide has an amino acid change (e.g., deletion, insertion, or substitution) that reduces the nuclease activity of the Cas9 polypeptide. For example, in some instances, the variant Cas9 polypeptide has less than 50%, less than 40%, less than 30%, less than 20%, less than 10%, less than 5%, or less than 1% of the nuclease activity of the corresponding wild-type Cas9 protein. In some cases, the variant Cas9 protein has no substantial nuclease activity. When a subject Cas9 protein is a variant Cas9 protein that has no substantial nuclease activity, it can be referred to as “dCas9.”

[0285] In some cases, a variant Cas9 protein has reduced nuclease activity. For example, a variant Cas9 protein exhibits less than about 20%, less than about 15%, less than about 10%, less than about 5%, less than about 1%, or less than about 0.1%, of the endonuclease activity of a wild-type Cas9 protein, e.g., a wild-type Cas9 protein.

[0286] In some cases, a variant Cas9 protein can cleave the complementary strand of a guide target sequence but has reduced ability to cleave the non-complementary strand of a double stranded guide target sequence. For example, the variant Cas9 protein can have a mutation (amino acid substitution) that reduces the function of the RuvC domain. As a non-limiting example, in some embodiments, a variant Cas9 protein has a D10A (aspartate to alanine at amino acid position 10) and can therefore cleave the complementary strand of a double stranded guide target sequence but has reduced ability to cleave the non-complementary strand of a double stranded guide target sequence (thus resulting in a single strand break (SSB) instead of a double strand break (DSB) when the variant Cas9 protein cleaves a double stranded target nucleic acid) (see, for example, Jinek et al., Science. 2012 Aug. 17; 337(6096):816-21).

[0287] In some cases, a variant Cas9 protein can cleave the non-complementary strand of a double stranded guide target sequence but has reduced ability to cleave the complementary strand of the guide target sequence. For example, the variant Cas9 protein can have a mutation (amino acid substitution) that reduces the function of the HNH domain (RuvC/HNH/RuvC domain motifs). As a non-limiting example, in some embodiments, the variant Cas9 protein has an H840A (histidine to alanine at amino acid position 840) mutation and can therefore cleave the non-complementary strand of the guide target sequence but has reduced ability to cleave the complementary strand of the guide target sequence (thus resulting in a SSB instead of a DSB when the variant Cas9 protein cleaves a double stranded guide target sequence). Such a Cas9 protein has a reduced ability to cleave a guide target sequence (e.g., a single stranded guide target sequence) but retains the ability to bind a guide target sequence (e.g., a single stranded guide target sequence).

[0288] In some cases, a variant Cas9 protein has a reduced ability to cleave both the complementary and the non-complementary strands of a double stranded target DNA. As a non-limiting example, in some cases, the variant Cas9 protein harbors both the D10A and the H840A mutations such that the polypeptide has a reduced ability to cleave both the complementary and the non-complementary strands of a double stranded target DNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA).

[0289] As another non-limiting example, in some cases, the variant Cas9 protein harbors W476A and W1126A mutations such that the polypeptide has a reduced ability to cleave a target DNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA).

[0290] As another non-limiting example, in some cases, the variant Cas9 protein harbors P475A, W476A, N477A, D1125A, W1126A, and D1127A mutations such that the polypeptide has a reduced ability to cleave a target DNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA).

[0291] As another non-limiting example, in some cases, the variant Cas9 protein harbors H840A, W476A, and W1126A, mutations such that the polypeptide has a reduced ability to cleave a target DNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA). As another non-limiting example, in some cases, the variant Cas9 protein harbors H840A, D10A, W476A, and W1126A, mutations such that the polypeptide has a reduced ability to cleave a target DNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA). In some embodiments, the variant Cas9 has restored catalytic His residue at position 840 in the Cas9 HNH domain (A840H).

[0292] As another non-limiting example, in some cases, the variant Cas9 protein harbors, H840A, P475A, W476A, N477A, D1125A, W1126A, and D1127A mutations such that the polypeptide has a reduced ability to cleave a target DNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA). As another non-limiting example, in some cases, the variant Cas9 protein harbors D10A, H840A, P475A, W476A, N477A, D1125A, W1126A, and D1127A mutations such that the polypeptide has a reduced ability to cleave a target DNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA). In some cases, when a variant Cas9 protein harbors W476A and W1126A mutations or when the variant Cas9 protein harbors P475A, W476A, N477A, D1125A, W1126A, and D1127A mutations, the variant Cas9 protein does not bind efficiently to a PAM sequence. Thus, in some such cases, when such a variant Cas9 protein is used in a method of binding, the method does not require a PAM sequence. In other words, in some cases, when such a variant Cas9 protein is used in a method of binding, the method can include a guide RNA, but the method can be performed in the absence of a PAM sequence (and the specificity of binding is therefore provided by the targeting segment of the guide RNA). Other residues can be mutated to achieve the above effects (i.e., inactivate one or the other nuclease portions). As non-limiting examples, residues D10, G12, G17, E762, H840, N854, N863, H982, H983, A984, D986, and/or A987 can be altered (i.e., substituted). Also, mutations other than alanine substitutions are suitable.

[0293] In some embodiments, a variant Cas9 protein that has reduced catalytic activity (e.g., when a Cas9 protein has a D10, G12, G17, E762, H840, N854, N863, H982, H983, A984, D986, and/or a A987 mutation, e.g., D10A, G12A, G17A, E762A, H840A, N854A, N863A, H982A, H983A, A984A, and/or D986A), the variant Cas9 protein can still bind to target DNA in a site-specific manner (because it is still guided to a target DNA sequence by a guide RNA) as long as it retains the ability to interact with the guide RNA.

[0294] In some embodiments, the variant Cas protein can be spCas9, spCas9-VRQR, spCas9-VRER, xCas9 (sp), saCas9, saCas9-KKH, SpCas9-MQKFRAER, spCas9-MQKSER, spCas9-LRKIQK, or spCas9-LRVSQL.

[0295] In one specific embodiment, a modified SpCas9 including amino acid substitutions D1135M, 51136Q, G1218K, E1219F, A1322R, D1332A, R1335E, and T1337R (SpCas9-MQKFRAER) and having specificity for the altered PAM 5′-NGC-3′ is used.

[0296] Alternatives to S. pyogenes Cas9 can include RNA-guided endonucleases from the Cpf1 family that display cleavage activity in mammalian cells. CRISPR from Prevotella and Francisella 1 (CRISPR/Cpf1) is a DNA-editing technology analogous to the CRISPR/Cas9 system. Cpf1 is an RNA-guided endonuclease of a class II CRISPR/Cas system. This acquired immune mechanism is found in Prevotella and Francisella bacteria. Cpf1 genes are associated with the CRISPR locus, coding for an endonuclease that use a guide RNA to find and cleave viral DNA. Cpf1 is a smaller and simpler endonuclease than Cas9, overcoming some of the CRISPR/Cas9 system limitations. Unlike Cas9 nucleases, the result of Cpf1-mediated DNA cleavage is a double-strand break with a short 3′ overhang. Cpf1's staggered cleavage pattern can open up the possibility of directional gene transfer, analogous to traditional restriction enzyme cloning, which can increase the efficiency of gene editing Like the Cas9 variants and orthologues described above, Cpf1 can also expand the number of sites that can be targeted by CRISPR to AT-rich regions or AT-rich genomes that lack the NGG PAM sites favored by SpCas9. The Cpf1 locus contains a mixed alpha/beta domain, a RuvC-I followed by a helical region, a RuvC-II and a zinc finger-like domain. The Cpf1 protein has a RuvC-like endonuclease domain that is similar to the RuvC domain of Cas9. Furthermore, Cpf1 does not have a HNH endonuclease domain, and the N-terminal of Cpf1 does not have the alpha-helical recognition lobe of Cas9. Cpf1 CRISPR-Cas domain architecture shows that Cpf1 is functionally unique, being classified as Class 2, type V CRISPR system. The Cpf1 loci encode Cas1, Cas2 and Cas4 proteins more similar to types I and III than from type II systems. Functional Cpf1 doesn't need the trans-activating CRISPR RNA (tracrRNA), therefore, only CRISPR (crRNA) is required. This benefits genome editing because Cpf1 is not only smaller than Cas9, but also it has a smaller sgRNA molecule (proximately half as many nucleotides as Cas9). The Cpf1-crRNA complex cleaves target DNA or RNA by identification of a protospacer adjacent motif 5′-YTN-3′ in contrast to the G-rich PAM targeted by Cas9. After identification of PAM, Cpf1 introduces a sticky-end-like DNA double-stranded break of 4 or 5 nucleotides overhang.

[0297] Some aspects of the disclosure provide a nucleic acid programmable DNA binding protein domain and a deaminase domain. Some aspects of the disclosure provide fusion proteins comprising domains that act as nucleic acid programmable DNA binding proteins, which may be used to guide a protein, such as a base editor, to a specific nucleic acid (e.g., DNA or RNA) sequence. In particular embodiments, a fusion protein comprises a nucleic acid programmable DNA binding protein domain and a deaminase domain. DNA binding proteins include, without limitation, Cas9 (e.g., dCas9 and nCas9), Cas12a/Cpf1, Cas12b/C2c1, Cas12c/C2c3, Cas12d/CasY, Cas12e/CasX, Cas12g, Cas12h, and Cas12i. One example of a programmable polynucleotide-binding protein that has different PAM specificity than Cas9 is Clustered Regularly Interspaced Short Palindromic Repeats from Prevotella and Francisella1 (Cpf1). Similar to Cas9, Cpf1 is also a class 2 CRISPR effector. It has been shown that Cpf1 mediates robust DNA interference with features distinct from Cas9. Cpf1 is a single RNA-guided endonuclease lacking tracrRNA, and it utilizes a T-rich protospacer-adjacent motif (TTN, TTTN, or YTN). Moreover, Cpf1 cleaves DNA via a staggered DNA double-stranded break. Out of 16 Cpf1-family proteins, two enzymes from Acidaminococcus and Lachnospiraceae are shown to have efficient genome-editing activity in human cells. Cpf1 proteins are known in the art and have been described previously, for example Yamano et al., “Crystal structure of Cpf1 in complex with guide RNA and target DNA.” Cell (165) 2016, p. 949-962; the entire contents of which is hereby incorporated by reference.

[0298] Also useful in the present compositions and methods are nuclease-inactive Cpf1 (dCpf1) variants that may be used as a guide nucleotide sequence-programmable polynucleotide-binding protein domain. The Cpf1 protein has a RuvC-like endonuclease domain that is similar to the RuvC domain of Cas9 but does not have a HNH endonuclease domain, and the N-terminal of Cpf1 does not have the alfa-helical recognition lobe of Cas9. It was shown in Zetsche et al., Cell, 163, 759-771, 2015 (which is incorporated herein by reference) that, the RuvC-like domain of Cpf1 is responsible for cleaving both DNA strands and inactivation of the RuvC-like domain inactivates Cpf1 nuclease activity. For example, mutations corresponding to D917A, E1006A, or D1255A in Francisella novicida Cpf1 inactivate Cpf1 nuclease activity. In some embodiments, the dCpf1 of the present disclosure comprises mutations corresponding to D917A, E1006A, D1255A, D917A/E1006A, D917A/D1255A, E1006A/D1255A, or D917A/E1006A/D1255A. It is to be understood that any mutations, e.g., substitution mutations, deletions, or insertions that inactivate the RuvC domain of Cpf1, may be used in accordance with the present disclosure.

[0299] In some embodiments, the nucleic acid programmable nucleotide binding protein of any of the fusion proteins provided herein may be a Cpf1 protein. In some embodiments, the Cpf1 protein is a Cpf1 nickase (nCpf1). In some embodiments, the Cpf1 protein is a nuclease inactive Cpf1 (dCpf1). In some embodiments, the Cpf1, the nCpf1, or the dCpf1 comprises an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to a Cpf1 sequence disclosed herein. In some embodiments, the dCpf1 comprises an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at ease 99.5% identical to a Cpf1 sequence disclosed herein, and comprises mutations corresponding to D917A, E1006A, D1255A, D917A/E1006A, D917A/D1255A, E1006A/D1255A, or D917A/E1006A/D1255A. It should be appreciated that Cpf1 from other bacterial species may also be used in accordance with the present disclosure.

[0300] The amino acid sequence of wild type Francisella novicida Cpf1 follows. D917, E1006, and D1255 are bolded and underlined.

TABLE-US-00035 MSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKA KQIIDKYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKS AKDTIKKQISEYIKDSEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGI ELFKANSDITDIDEALEIIKSFKGWTTYFKGFHENRKNVYSSNDIPTSII YRIVDDNLPKFLENKAKYESLKDKAPEAINYEQIKKDLAEELTFDIDYKT SEVNQRVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENTKRKGI NEYINLYSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVT TMQSFYEQIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLT DLSQQVFDDYSVIGTAVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKY LSLETIKLALEEFNKHRDIDKQCRFEEILANFAAIPMIFDEIAQNKDNLA QISIKYQNQGKKDLLQASAEDDVKAIKDLLDQTNNLLHKLKIFHISQSED KANILDKDEHFYLVFEECYFELANIVPLYNKIRNYITQKPYSDEKFKLNF ENSTLANGWDKNKEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENK GEGYKKIVYKLLPGANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKN GSPQKGYEKFEFNIEDCRKFIDFYKQSISKHPEWKDFGFRFSDTQRYNSI DEFYREVENQGYKLTFENISESYIDSVVNQGKLYLFQIYNKDFSAYSKGR PNLHTLYWKALFDERNLQDVVYKLNGEAELFYRKQSIPKKITHPAKEAIA NKNKDNPKKESVFEYDLIKDKRFTEDKFFFHCPITINFKSSGANKFNDEI NLLLKEKANDVHILSI RGERHLAYYTLVDGKGNIIKQDTFNIIGNDRMK TNYHDKLAAIEKDRDSARKDWKKINNIKEMKEGYLSQVVHEIAKLVIEYN AIVVF DLNFGFKRGRFKVEKQVYQKLEKMLIEKLNYLVFKDNEFDKTGG VLRAYQLTAPFETFKKMGKQTGIIYYVPAGFTSKICPVTGFVNQLYPKYE SVSKSQEFFSKFDKICYNLDKGYFEFSFDYKNFGDKAAKGKWTIASFGSR LINFRNSDKNHNWDTREVYPTKELEKLLKDYSIEYGHGECIKAAICGESD KKFFAKLTSVLNTILQMRNSKTGTELDYLISPVADVNGNFFDSRQAPKNM PQDA ANGAYHIGLKGLMLLGRIKNNQEGKKLNLVIKNEEYFEFVQNRN N.

[0301] The amino acid sequence of Francisella novicida Cpf1 D917A follows. (A917,

[0302] E1006, and D1255 are bolded and underlined).

TABLE-US-00036 MSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKAK QIIDKYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKSAK DTIKKQISEYIKDSEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGIELF KANSDITDIDEALEIIKSFKGWTTYFKGFHENRKNVYSSNDIPTSIIYRIV DDNLPKFLENKAKYESLKDKAPEAINYEQIKKDLAEELTFDIDYKTSEVNQ RVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENTKRKGINEYINL YSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVTTMQSFYE QIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLTDLSQQVFD DYSVIGTAVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKYLSLETIKLA LEEFNKHRDIDKQCRFEEILANFAAIPMIFDEIAQNKDNLAQISIKYQNQG KKDLLQASAEDDVKAIKDLLDQTNNLLHKLKIFHISQSEDKANILDKDEHF YLVFEECYFELANIVPLYNKIRNYITQKPYSDEKFKLNFENSTLANGWDKN KEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENKGEGYKKIVYKLLP GANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKNGSPQKGYEKFEFNI EDCRKFIDFYKQSISKHPEWKDFGFRFSDTQRYNSIDEFYREVENQGYKLT FENISESYIDSVVNQGKLYLFQIYNKDFSAYSKGRPNLHTLYWKALFDERN LQDVVYKLNGEAELFYRKQSIPKKITHPAKEAIANKNKDNPKKESVFEYDL IKDKRFTEDKFFFHCPITINFKSSGANKFNDEINLLLKEKANDVHILSI R GERHLAYYTLVDGKGNIIKQDTFNIIGNDRMKTNYHDKLAAIEKDRDSARK DWKKINNIKEMKEGYLSQVVHEIAKLVIEYNAIVVF DLNFGFKRGRFKVE KQVYQKLEKMLIEKLNYLVFKDNEFDKTGGVLRAYQLTAPFETFKKMGKQT GIIYYVPAGFTSKICPVTGFVNQLYPKYESVSKSQEFFSKFDKICYNLDKG YFEFSFDYKNFGDKAAKGKTNTIASFGSRLINFRNSDKNHWDTREVYPTKE LEKLLKDYSIEYGHGECIKAAICGESDKKFFAKLTSVLNTILQMRNSKTGT ELDYLISPVADVNGNFFDSRQAPKNMPQDA ANGAYHIGLKGLMLLGRIKN NQEGKKLNLVIKNEEYFEFVQNRNN.

[0303] The amino acid sequence of Francisella novicida Cpf1 E1006A follows. (D917, A1006, and D1255 are bolded and underlined).

TABLE-US-00037 MSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKAK QIIDKYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKSAK DTIKKQISEYIKDSEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGIELF KANSDITDIDEALEIIKSFKGWTTYFKGFHENRKNVYSSNDIPTSIIYRIV DDNLPKFLENKAKYESLKDKAPEAINYEQIKKDLAEELTFDIDYKTSEVNQ RVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENTKRKGINEYINL YSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVTTMQSFYE QIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLTDLSQQVFD DYSVIGTAVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKYLSLETIKLA LEEFNKHRDIDKQCRFEEILANFAAIPMIFDEIAQNKDNLAQISIKYQNQG KKDLLQASAEDDVKAIKDLLDQTNNLLHKLKIFHISQSEDKANILDKDEHF YLVFEECYFELANIVPLYNKIRNYITQKPYSDEKFKLNFENSTLANGWDKN KEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENKGEGYKKIVYKLLP GANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKNGSPQKGYEKFEFNI EDCRKFIDFYKQSISKHPEWKDFGFRFSDTQRYNSIDEFYREVENQGYKLT FENISESYIDSVVNQGKLYLFQIYNKDFSAYSKGRPNLHTLYWKALFDERN LQDVVYKLNGEAELFYRKQSIPKKITHPAKEAIANKNKDNPKKESVFEYDL IKDKRFTEDKFFFHCPITINFKSSGANKFNDEINLLLKEKANDVHILSI R GERHLAYYTLVDGKGNIIKQDTFNIIGNDRMKTNYHDKLAAIEKDRDSARK DWKKINNIKEMKEGYLSQVVHEIAKLVIEYNAIVVF DLNFGFKRGRFKVE KQVYQKLEKMLIEKLNYLVFKDNEFDKTGGVLRAYQLTAPFETFKKMGKQT GIIYYVPAGFTSKICPVTGFVNQLYPKYESVSKSQEFFSKFDKICYNLDKG YFEFSFDYKNFGDKAAKGKWTIASFGSRLINFRNSDKNHNWDTREVYPTKE LEKLLKDYSIEYGHGECIKAAICGESDKKFFAKLTSVLNTILQMRNSKTGT ELDYLISPVADVNGNFFDSRQAPKNMPQDA ANGAYHIGLKGLMLLGRIKN NQEGKKLNLVIKNEEYFEFVQNRNN.

[0304] The amino acid sequence of Francisella novicida Cpf1 D1255A follows. (D917, E1006, and A1255 mutation positions are bolded and underlined).

TABLE-US-00038 MSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKAK QIIDKYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKSAK DTIKKQISEYIKDSEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGIELF KANSDITDIDEALEIIKSFKGWTTYFKGFHENRKNVYSSNDIPTSIIYRIV DDNLPKFLENKAKYESLKDKAPEAINYEQIKKDLAEELTFDIDYKTSEVNQ RVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENTKRKGINEYINL YSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVTTMQSFYE QIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLTDLSQQVFD DYSVIGTAVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKYLSLETIKLA LEEFNKHRDIDKQCRFEEILANFAAIPMIFDEIAQNKDNLAQISIKYQNQG KKDLLQASAEDDVKAIKDLLDQTNNLLHKLKIFHISQSEDKANILDKDEHF YLVFEECYFELANIVPLYNKIRNYITQKPYSDEKFKLNFENSTLANGWDKN KEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENKGEGYKKIVYKLLP GANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKNGSPQKGYEKFEFNI EDCRKFIDFYKQSISKHPEWKDFGFRFSDTQRYNSIDEFYREVENQGYKLT FENISESYIDSVVNQGKLYLFQIYNKDFSAYSKGRPNLHTLYWKALFDERN LQDVVYKLNGEAELFYRKQSIPKKITHPAKEAIANKNKDNPKKESVFEYDL IKDKRFTEDKFFFHCPITINFKSSGANKFNDEINLLLKEKANDVHILSI R GERHLAYYTLVDGKGNIIKQDTFNIIGNDRMKTNYHDKLAAIEKDRDSARK DWKKINNIKEMKEGYLSQVVHEIAKLVIEYNAIVVF DLNFGFKRGRFKVE KQVYQKLEKMLIEKLNYLVFKDNEFDKTGGVLRAYQLTAPFETFKKMGKQT GIIYYVPAGFTSKICPVTGFVNQLYPKYESVSKSQEFFSKFDKICYNLDKG YFEFSFDYKNFGDKAAKGKWTIASFGSRLINFRNSDKNHNWDTREVYPTKE LEKLLKDYSIEYGHGECIKAAICGESDKKFFAKLTSVLNTILQMRNSKTGT ELDYLISPVADVNGNFFDSRQAPKNMPQDA NGAYHIGLKGLMLLGRIKNN QEGKKLNLVIKNEEYFEFVQNRNN

[0305] The amino acid sequence of Francisella novicida Cpf1 D917A/E1006A follows. (A917, A1006, and D1255 are bolded and underlined).

TABLE-US-00039 MSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKAK QIIDKYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKSAK DTIKKQISEYIKDSEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGIELF KANSDITDIDEALEIIKSFKGWTTYFKGFHENRKNVYSSNDIPTSIIYRIV DDNLPKFLENKAKYESLKDKAPEAINYEQIKKDLAEELTFDIDYKTSEVNQ RVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENTKRKGINEYINL YSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVTTMQSFYE QIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLTDLSQQVFD DYSVIGTAVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKYLSLETIKLA LEEFNKHRDIDKQCRFEEILANFAAIPMIFDEIAQNKDNLAQISIKYQNQG KKDLLQASAEDDVKAIKDLLDQTNNLLHKLKIFHISQSEDKANILDKDEHF YLVFEECYFELANIVPLYNKIRNYITQKPYSDEKFKLNFENSTLANGWDKN KEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENKGEGYKKIVYKLLP GANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKNGSPQKGYEKFEFNI EDCRKFIDFYKQSISKHPEWKDFGFRFSDTQRYNSIDEFYREVENQGYKLT FENISESYIDSVVNQGKLYLFQIYNKDFSAYSKGRPNLHTLYWKALFDERN LQDVVYKLNGEAELFYRKQSIPKKITHPAKEAIANKNKDNPKKESVFEYDL IKDKRFTEDKFFFHCPITINFKSSCANKFNDEINLLLKEKANDVHILSI R CERHLAYYTLVDGKGNIIKQDTFNIIGNDRMKTNYHDKLAAIEKDRDSARK DWKKINNIKEMKEGYLSQVVHEIAKLVIEYNAIVVF DLNFGFKRGRFKVE KQVYQKLEKMLIEKLNYLVFKDNEFDKTGGVLRAYQLTAPFETFKKMGKQT GIIYYVPAGFTSKICPVTGFVNQLYPKYESVSKSQEFFSKFDKICYNLDKG YFEFSFDYKNFGDKAAKGKWTIASFGSRLINFRNSDKNHNWDTREVYPTKE LEKLLKDYSIEYGHGECIKAAICGESDKKFFAKLTSVLNTILQMRNSKTGT ELDYLISPVADVNGNFFDSRQAPKNMPQDA ANGAYHIGLKGLMLLGRIKN NQEGKKLNLVIKNEEYFEFVQNRNN.

[0306] The amino acid sequence of Francisella novicida Cpf1 D917A/D1255A follows. (A917, E1006, and A1255 are bolded and underlined).

TABLE-US-00040 MSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKAK QIIDKYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKSAK DTIKKQISEYIKDSEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGIELF KANSDITDIDEALEIIKSFKGWTTYFKGFHENRKNVYSSNDIPTSIIYRIV DDNLPKFLENKAKYESLKDKAPEAINYEQIKKDLAEELTFDIDYKTSEVNQ RVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENTKRKGINEYINL YSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVTTMQSFYE QIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLTDLSQQVFD DYSVIGTAVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKYLSLETIKLA LEEFNKHRDIDKQCRFEEILANFAAIPMIFDEIAQNKDNLAQISIKYQNQG KKDLLQASAEDDVKAIKDLLDQTNNLLHKLKIFHISQSEDKANILDKDEHF YLVFEECYFELANIVPLYNKIRNYITQKPYSDEKFKLNFENSTLANGWDKN KEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENKGEGYKKIVYKLLP GANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKNGSPQKGYEKFEFNI EDCRKFIDFYKQSISKHPEWKDFGFRFSDTQRYNSIDEFYREVENQGYKLT FENISESYIDSVVNQGKLYLFQIYNKDFSAYSKGRPNLHTLYWKALFDERN LQDVVYKLNGEAELFYRKQSIPKKITHPAKEAIANKNKDNPKKESVFEYDL IKDKRFTEDKFFFHCPITINFKSSGANKFNDEINLLLKEKANDVHILSI R GERHLAYYTLVDGKGNIIKQDTFNIIGNDRMKTNYHDKLAAIEKDRDSARK DWKKINNIKEMKEGYLSQVVHEIAKLVIEYNAIVVF DLNFGFKRGRFKVE KQVYQKLEKMLIEKLNYLVFKDNEFDKTGGVLRAYQLTAPFETFKKMGKQT GIIYYVPAGFTSKICPVTGFVNQLYPKYESVSKSQEFFSKFDKICYNLDKG YFEFSFDYKNFGDKAAKGKWTIASFGSRLINFRNSDKNHNWDTREVYPTKE LEKLLKDYSIEYGHGECIKAAICGESDKKFFAKLTSVLNTILQMRNSKTGT ELDYLISPVADVNGNFFDSRQAPKNMPQDA NGAYHIGLKGLMLLGRIKNN QEGKKLNLVIKNEEYFEFVQNRNN.

[0307] The amino acid sequence of Francisella novicida Cpf1 E1006A/D1255A follows. (D917, A1006, and A1255 are bolded and underlined).

TABLE-US-00041 MSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKAK QIIDKYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKSAK DTIKKQISEYIKDSEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGIELF KANSDITDIDEALEIIKSFKGWTTYFKGFHENRKNVYSSNDIPTSIIYRIV DDNLPKFLENKAKYESLKDKAPEAINYEQIKKDLAEELTFDIDYKTSEVNQ RVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENTKRKGINEYINL YSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVTTMQSFYE QIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLTDLSQQVFD DYSVIGTAVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKYLSLETIKLA LEEFNKHRDIDKQCRFEEILANFAAIPMIFDEIAQNKDNLAQISIKYQNQG KKDLLQASAEDDVKAIKDLLDQTNNLLHKLKIFHISQSEDKANILDKDEHF YLVFEECYFELANIVPLYNKIRNYITQKPYSDEKFKLNFENSTLANGWDKN KEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENKGEGYKKIVYKLLP GANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKNGSPQKGYEKFEFNI EDCRKFIDFYKQSISKHPEWKDFGFRFSDTQRYNSIDEFYREVENQGYKLT FENISESYIDSVVNQGKLYLFQIYNKDFSAYSKGRPNLHTLYWKALFDERN LQDVVYKLNGEAELFYRKQSIPKKITHPAKEAIANKNKDNPKKESVFEYDL IKDKRFTEDKFFFHCPITINFKSSGANKFNDEINLLLKEKANDVHILSI R GERHLAYYTLVDGKGNIIKQDTFNIIGNDRMKTNYHDKLAAIEKDRDSARK DWKKINNIKEMKEGYLSQVVHEIAKLVIEYNAIVVF DLNFGFKRGRFKVE KQVYQKLEKMLIEKLNYLVFKDNEFDKTGGVLRAYQLTAPFETFKKMGKQT GIIYYVPAGFTSKICPVTGFVNQLYPKYESVSKSQEFFSKFDKICYNLDKG YFEFSFDYKNFGDKAAKGKWTIASFGSRLINFRNSDKNHNWDTREVYPTKE LEKLLKDYSIEYGHGECIKAAICGESDKKFFAKLTSVLNTILQMRNSKTGT ELDYLISPVADVNGNFFDSRQAPKNMPQDA NGAYHIGLKGLMLLGRIKNN QEGKKLNLVIKNEEYFEFVQNRNN.

[0308] The amino acid sequence of Francisella novicida Cpf1 D917A/E1006A/D1255A follows. (A917, A1006, and A1255 are bolded and underlined).

TABLE-US-00042 MSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKAK QIIDKYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKSAK DTIKKQISEYIKDSEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGIELF KANSDITDIDEALEIIKSFKGWTTYFKGFHENRKNVYSSNDIPTSIIYRIV DDNLPKFLENKAKYESLKDKAPEAINYEQIKKDLAEELTFDIDYKTSEVNQ RVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENTKRKGINEYINL YSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVTTMQSFYE QIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLTDLSQQVFD DYSVIGTAVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKYLSLETIKLA LEEFNKHRDIDKQCRFEEILANFAAIPMIFDEIAQNKDNLAQISIKYQNQG KKDLLQASAEDDVKAIKDLLDQTNNLLHKLKIFHISQSEDKANILDKDEHF YLVFEECYFELANIVPLYNKIRNYITQKPYSDEKFKLNFENSTLANGWDKN KEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENKGEGYKKIVYKLLP GANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKNCSPQKCYEKFEFNI EDCRKFIDFYKQSISKHPEWKDFCFRFSDTQRYNSIDEFYREVENQGYKLT FENISESYIDSVVNQGKLYLFQIYNKDFSAYSKGRPNLHTLYWKALFDERN LQDVVYKLNGEAELFYRKQSIPKKITHPAKEAIANKNKDNPKKESVFEYDL IKDKRFTEDKFFFHCPITINFKSSGANKFNDEINLLLKEKANDVHILSI R GERHLAYYTLVDGKGNIIKQDTFNIIGNDRMKTNYHDKLAAIEKDRDSARK DWKKINNIKEMKEGYLSQVVHEIAKLVIEYNAIVVF DLNFGFKRGRFKVE KQVYQKLEKMLIEKLNYLVFKDNEFDKTGGVLRAYQLTAPFETFKKMGKQT GIIYYVPAGFTSKICPVTGFVNQLYPKYESVSKSQEFFSKFDKICYNLDKG YFEFSFDYKNFGDKAAKGKWTIASFGSRLINFRNSDKNHNWDTREVYPTKE LEKLLKDYSIEYGHGECIKAAICGESDKKFFAKLTSVLNTILQMRNSKTGT ELDYLISPVADVNGNFFDSRQAPKNMPQDA ANGAYHIGLKGLMLLGRIKN NQEGKKLNLVIKNEEYFEFVQNRNN.

[0309] In some embodiments, one of the Cas9 domains present in the fusion protein may be replaced with a guide nucleotide sequence-programmable DNA-binding protein domain that has no requirements for a PAM sequence.

[0310] In some embodiments, the Cas domain is a Cas9 domain from Staphylococcus aureus (SaCas9). In some embodiments, the SaCas9 domain is a nuclease active SaCas9, a nuclease inactive SaCas9 (SaCas9d), or a SaCas9 nickase (SaCas9n). In some embodiments, the SaCas9 domain comprises a N579A mutation, or a corresponding mutation in any of the amino acid sequences provided herein.

[0311] In some embodiments, the SaCas9 domain, the SaCas9d domain, or the SaCas9n domain can bind to a nucleic acid sequence having a non-canonical PAM. In some embodiments, the SaCas9 domain, the SaCas9d domain, or the SaCas9n domain can bind to a nucleic acid sequence having a NNGRRT or a NNGRRT PAM sequence. In some embodiments, the SaCas9 domain comprises one or more of a E781X, a N967X, and a R1014X mutation, or a corresponding mutation in any of the amino acid sequences provided herein, wherein X is any amino acid. In some embodiments, the SaCas9 domain comprises one or more of a E781K, a N967K, and a R1014H mutation, or one or more corresponding mutation in any of the amino acid sequences provided herein. In some embodiments, the SaCas9 domain comprises a E781K, a N967K, or a R1014H mutation, or corresponding mutations in any of the amino acid sequences provided herein.

[0312] The amino acid sequence of an exemplary SaCas9 is as follows:

TABLE-US-00043 MKRNYILGLDIGITSVGYGIIDYETRDVIDAGVRLFKEANVENNEGRRSKR GARRLKRRRRHRIQRVKKLLFDYNLLTDHSELSGINPYEARVKGLSQKLSE EEFSAALLHLAKRRGVHNVNEVEEDTGNELSTKEQISRNSKALEEKYVAEL QLERLKKDGEVRGSINRFKTSDYVKEAKQLLKVQKAYHQLDQSFIDTYIDL LETRRTYYEGPGEGSPFGWKDIKEWYEMLMGHCTYFPEELRSVKYAYNADL YNALNDLNNLVITRDENEKLEYYEKFQIIENVFKQKKKPTLKQIAKEILVN EEDIKGYRVTSTGKPEFTNLKVYHDIKDITARKEIIENAELLDQIAKILTI YQSSEDIQEELTNLNSELTQEEIEQISNLKGYTGTHNLSLKAINLILDELW HTNDNQIAIFNRLKLVPKKVDLSQQKEIPTTLVDDFILSPVVKRSFIQSIK VINAIIKKYGLPNDIIIELAREKNSKDAQKMINEMQKRNRQTNERIEEIIR TTGKENAKYLIEKIKLHDMQEGKCLYSLEAIPLEDLLNNPFNYEVDHIIPR SVSFDNSFNNKVLVKQEE SKKGNRTPFQYLSSSDSKISYETFKKHILNLA KGKGRISKTKKEYLLEERDINRFSVQKDFINRNLVDTRYATRGLMNLLRSY FRVNNLDVKVKSINGGFTSFLRRKWKFKKERNKGYKHHAEDALIIANADFI FKEWKKLDKAKKVMENQMFEEKQAESMPEIETEQEYKEIFITPHQIKHIKD FKDYKYSHRVDKKPNRELINDTLYSTRKDDKGNTLIVNNLNGLYDKDNDKL KKLINKSPEKLLMYHHDPQTYQKLKLIMEQYGDEKNPLYKYYEETGNYLTK YSKKDNGPVIKKIKYYGNKLNAHLDITDDYPNSRNKVVKLSLKPYRFDVYL DNGVYKFVTVKNLDVIKKENYYEVNSKCYEEAKKLKKISNQAEFIASFYNN DLIKINGELYRVIGVNNDLLNRIEVNMIDITYREYLENMNDKRPPRIIKTI ASKTQSIKKYSTDILGNLYEVKSKKHPQIIKKG.
In this sequence, residue N579, which is underlined and in bold, may be mutated (e.g., to a A579) to yield a SaCas9 nickase.

[0313] The amino acid sequence of an exemplary SaCas9n is as follows:

TABLE-US-00044 KRNYILGLDIGITSVGYGIIDYETRDVIDAGVRLFKEANVENNEGRRSKRG ARRLKRRRRHRIQRVKKLLFDYNLLTDHSELSGINPYEARVKGLSQKLSEE EFSAALLHLAKRRGVHNVNEVEEDTGNELSTKEQISRNSKALEEKYVAELQ LERLKKDGEVRGSINRFKTSDYVKEAKQLLKVQKAYHQLDQSFIDTYIDLL ETRRTYYEGPGEGSPFGWKDIKEWYEMLMGHCTYFPEELRSVKYAYNADLY NALNDLNNLVITRDENEKLEYYEKFQIIENVFKQKKKPTLKQIAKEILVNE EDIKGYRVTSTGKPEFTNLKVYHDIKDITARKEIIENAELLDQIAKILTIY QSSEDIQEELTNLNSELTQEEIEQISNLKGYTGTHNLSLKAINLILDELWH TNDNQIAIFNRLKLVPKKVDLSQQKEIPTTLVDDFILSPVVKRSFIQSIKV INAIIKKYGLPNDIIIELAREKNSKDAQKMINEMQKRNRQTNERIEEIIRT TGKENAKYLIEKIKLHDMQEGKCLYSLEAIPLEDLLNNPFNYEVDHIIPRS VSFDNSFNNKVLVKQEE SKKGNRTPFQYLSSSDSKISYETFKKHILNLAK GKGRISKTKKEYLLEERDINRFSVQKDFINRNLVDTRYATRGLMNLLRSYF RVNNLDVKVKSINGGFTSFLRRKWKFKKERNKGYKHHAEDALIIANADFIF KEWKKLDKAKKVMENQMFEEKQAESMPEIETEQEYKEIFITPHQIKHIKDF KDYKYSHRVDKKPNRELINDTLYSTRKDDKGNTLIVNNLNGLYDKDNDKLK KLINKSPEKLLMYHHDPQTYQKLKLIMEQYGDEKNPLYKYYEETGNYLTKY SKKDNGPVIKKIKYYGNKLNAHLDITDDYPNSRNKVVKLSLKPYRFDVYLD NGVYKFVTVKNLDVIKKENYYEVNSKCYEEAKKLKKISNQAEFIASFYNND LIKINGELYRVIGVNNDLLNRIEVNMIDITYREYLENMNDKRPPRIIKTIA SKTQSIKKYSTDILGNLYEVKSKKHPQIIKKG.

[0314] In this sequence, residue A579, which can be mutated from N579 to yield a SaCas9 nickase, is underlined and in bold.

[0315] The amino acid sequences of an exemplary SaKKH Cas9 is as follows:

TABLE-US-00045 KRNYILGLDIGITSVGYGIIDYETRDVIDAGVRLFKEANVENNEGRRSKRG ARRLKRRRRHRIQRVKKLLFDYNLLTDHSELSGINPYEARVKGLSQKLSEE EFSAALLHLAKRRGVHNVNEVEEDTGNELSTKEQISRNSKALEEKYVAELQ LERLKKDGEVRGSINRFKTSDYVKEAKQLLKVQKAYHQLDQSFIDTYIDLL ETRRTYYEGPGEGSPFGWKDIKEWYEMLMGHCTYFPEELRSVKYAYNADLY NALNDLNNLVITRDENEKLEYYEKFQIIENVFKQKKKPTLKQIAKEILVNE EDIKGYRVTSTGKPEFTNLKVYHDIKDITARKEIIENAELLDQIAKILTIY QSSEDIQEELTNLNSELTQEEIEQISNLKGYTGTHNLSLKAINLILDELWH TNDNQIAIFNRLKLVPKKVDLSQQKEIPTTLVDDFILSPVVKRSFIQSIKV INAIIKKYGLPNDIIIELAREKNSKDAQKMINEMQKRNRQTNERIEEIIRT TGKENAKYLIEKIKLHDMQEGKCLYSLEAIPLEDLLNNPFNYEVDHIIPRS VSFDNSFNNKVLVKQEE SKKGNRTPFQYLSSSDSKISYETFKKHILNLAK GKGRISKTKKEYLLEERDINRFSVQKDFINRNLVDTRYATRGLMNLLRSYF RVNNLDVKVKSINGGFTSFLRRKWKFKKERNKGYKHHAEDALIIANADFIF KEWKKLDKAKKVMENQMFEEKQAESMPEIETEQEYKEIFITPHQIKHIKDF KDYKYSHRVDKKPNRKLINDTLYSTRKDDKGNTLIVNNLNGLYDKDNDKLK KLINKSPEKLLMYHHDPQTYQKLKLIMEQYGDEKNPLYKYYEETGNYLTKY SKKDNGPVIKKIKYYGNKLNAHLDITDDYPNSRNKVVKLSLKPYRFDVYLD NGVYKFVTVKNLDVIKKENYYEVNSKCYEEAKKLKKISNQAEFIASFYKND LIKINGELYRVIGVNNDLLNRIEVNMIDITYREYLENMNDKRPPHIIKTIA SKTQSIKKYSTDILGNLYEVKSKKHPQIIKKG.

[0316] Residue A579 above, which can be mutated from N579 to yield a SaCas9 nickase, is underlined and in bold. Residues K781, K967, and H1014 above, which can be mutated from E781, N967, and R1014 to yield a SaKKH Cas9 are underlined and in italics.

High Fidelity Cas9 Domains

[0317] Some aspects of the disclosure provide high fidelity Cas9 domains. In some embodiments, high fidelity Cas9 domains are engineered Cas9 domains comprising one or more mutations that decrease electrostatic interactions between the Cas9 domain and the sugar-phosphate backbone of a DNA, relative to a corresponding wild-type Cas9 domain. High fidelity Cas9 domains that have decreased electrostatic interactions with the sugar-phosphate backbone of DNA can have less off-target effects. In some embodiments, the Cas9 domain (e.g., a wild type Cas9 domain) comprises one or more mutations that decrease the association between the Cas9 domain and the sugar-phosphate backbone of a DNA. In some embodiments, a Cas9 domain comprises one or more mutations that decreases the association between the Cas9 domain and the sugar-phosphate backbone of DNA by at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, or at least 70%.

[0318] In some embodiments, any of the Cas9 fusion proteins provided herein comprise one or more of a N497X, a R661X, a Q695X, and/or a Q926X mutation, or a corresponding mutation in any of the amino acid sequences provided herein, wherein X is any amino acid. In some embodiments, any of the Cas9 fusion proteins provided herein comprise one or more of a N497A, a R661A, a Q695A, and/or a Q926A mutation, or a corresponding mutation in any of the amino acid sequences provided herein. In some embodiments, the Cas9 domain comprises a D10A mutation, or a corresponding mutation in any of the amino acid sequences provided herein. Cas9 domains with high fidelity are known in the art and would be apparent to the skilled artisan. For example, Cas9 domains with high fidelity have been described in Kleinstiver, B. P., et al. “High-fidelity CRISPR-Cas9 nucleases with no detectable genome-wide off-target effects.” Nature 529, 490-495 (2016); and Slaymaker, I. M., et al. “Rationally engineered Cas9 nucleases with improved specificity.” Science 351, 84-88 (2015); the entire contents of each are incorporated herein by reference.

[0319] In some embodiments, the modified Cas9 is a high fidelity Cas9 enzyme. In some embodiments, the high fidelity Cas9 enzyme is SpCas9 (K855A), eSpCas9 (1.1), SpCas9-HF1, or hyper accurate Cas9 variant (HypaCas9). The modified Cas9 eSpCas9 (1.1) contains alanine substitutions that weaken the interactions between the HNH/RuvC groove and the non-target DNA strand, preventing strand separation and cutting at off-target sites. Similarly, SpCas9-HF1 lowers off-target editing through alanine substitutions that disrupt Cas9's interactions with the DNA phosphate backbone. HypaCas9 contains mutations (SpCas9 N692A/M694A/Q695A/H698A) in the REC3 domain that increase Cas9 proofreading and target discrimination. All three high fidelity enzymes generate less off-target editing than wildtype Cas9.

[0320] An exemplary high fidelity Cas9 is provided below.

High Fidelity Cas9 domain mutations relative to Cas9 are shown in bold and underline

TABLE-US-00046 MDKKYSIGL IGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGAL LFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLE ESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRL IYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENPINAS GVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSN FDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDIL RVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKN GYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNG SIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGN SRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT FDKNLPNEKVLPK HSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTV KQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEEN EDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWG LS RKLINGIRDKQSGKTILDFLKSDGFANRNFM LIHDDSLTFKEDIQKAQVS GQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHKPENIVIEMAR ENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYL QNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKS DNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIK RQLVETR ITKHVAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKD FQFYKVREINNYHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRK MIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGE IVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIAR KKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSS FEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGN ELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISE FSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPAAFKY FDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQLGGD.

Guide Polynucleotides

[0321] In an embodiment, the guide polynucleotide is a guide RNA. An RNA/Cas complex can assist in “guiding” Cas protein to a target DNA. Cas9/crRNA/tracrRNA endonucleolytically cleaves linear or circular dsDNA target complementary to the spacer. The target strand not complementary to crRNA is first cut endonucleolytically, then trimmed 3′-5′ exonucleolytically. In nature, DNA-binding and cleavage typically requires protein and both RNAs. However, single guide RNAs (“sgRNA”, or simply “gNRA”) can be engineered so as to incorporate aspects of both the crRNA and tracrRNA into a single RNA species. See, e.g., Jinek M. et al., Science 337:816-821(2012), the entire contents of which is hereby incorporated by reference. Cas9 recognizes a short motif in the CRISPR repeat sequences (the PAM or protospacer adjacent motif) to help distinguish self versus non-self. Cas9 nuclease sequences and structures are well known to those of skill in the art (see e.g., “Complete genome sequence of an M1 strain of Streptococcus pyogenes.” Ferretti, J. J. et al., Natl. Acad. Sci. U.S.A. 98:4658-4663(2001); “CRISPR RNA maturation by trans-encoded small RNA and host factor RNase III.” Deltcheva E. et al., Nature 471:602-607(2011); and “Programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity.” Jinek M. et al, Science 337:816-821(2012), the entire contents of each of which are incorporated herein by reference). Cas9 orthologs have been described in various species, including, but not limited to, S. pyogenes and S. thermophilus. Additional suitable Cas9 nucleases and sequences can be apparent to those of skill in the art based on this disclosure, and such Cas9 nucleases and sequences include Cas9 sequences from the organisms and loci disclosed in Chylinski, Rhun, and Charpentier, “The tracrRNA and Cas9 families of type II CRISPR-Cas immunity systems” (2013) RNA Biology 10:5, 726-737; the entire contents of which are incorporated herein by reference. In some embodiments, a Cas9 nuclease has an inactive (e.g., an inactivated) DNA cleavage domain, that is, the Cas9 is a nickase.

[0322] In some embodiments, the guide polynucleotide is at least one single guide RNA (“sgRNA” or “gNRA”). In some embodiments, the guide polynucleotide is at least one tracrRNA. In some embodiments, the guide polynucleotide does not require PAM sequence to guide the polynucleotide-programmable DNA-binding domain (e.g., Cas9 or Cpf1) to the target nucleotide sequence.

[0323] The polynucleotide programmable nucleotide binding domain (e.g., a CRISPR-derived domain) of the base editors disclosed herein can recognize a target polynucleotide sequence by associating with a guide polynucleotide. A guide polynucleotide (e.g., gRNA) is typically single-stranded and can be programmed to site-specifically bind (i.e., via complementary base pairing) to a target sequence of a polynucleotide, thereby directing a base editor that is in conjunction with the guide nucleic acid to the target sequence. A guide polynucleotide can be DNA. A guide polynucleotide can be RNA. In some cases, the guide polynucleotide comprises natural nucleotides (e.g., adenosine). In some cases, the guide polynucleotide comprises non-natural (or unnatural) nucleotides (e.g., peptide nucleic acid or nucleotide analogs). In some cases, the targeting region of a guide nucleic acid sequence can be at least 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 nucleotides in length. A targeting region of a guide nucleic acid can be between 10-30 nucleotides in length, or between 15-25 nucleotides in length, or between 15-20 nucleotides in length.

[0324] In some embodiments, a guide polynucleotide comprises two or more individual polynucleotides, which can interact with one another via for example complementary base pairing (e.g., a dual guide polynucleotide). For example, a guide polynucleotide can comprise a CRISPR RNA (crRNA) and a trans-activating CRISPR RNA (tracrRNA). For example, a guide polynucleotide can comprise one or more trans-activating CRISPR RNA (tracrRNA).

[0325] In type II CRISPR systems, targeting of a nucleic acid by a CRISPR protein (e.g., Cas9) typically requires complementary base pairing between a first RNA molecule (crRNA) comprising a sequence that recognizes the target sequence and a second RNA molecule (trRNA) comprising repeat sequences which forms a scaffold region that stabilizes the guide RNA-CRISPR protein complex. Such dual guide RNA systems can be employed as a guide polynucleotide to direct the base editors disclosed herein to a target polynucleotide sequence.

[0326] In some embodiments, the base editor provided herein utilizes a single guide polynucleotide (e.g., gRNA). In some embodiments, the base editor provided herein utilizes a dual guide polynucleotide (e.g., dual gRNAs). In some embodiments, the base editor provided herein utilizes one or more guide polynucleotide (e.g., multiple gRNA). In some embodiments, a single guide polynucleotide is utilized for different base editors described herein. For example, a single guide polynucleotide can be utilized for a cytidine base editor and an adenosine base editor.

[0327] In other embodiments, a guide polynucleotide can comprise both the polynucleotide targeting portion of the nucleic acid and the scaffold portion of the nucleic acid in a single molecule (i.e., a single-molecule guide nucleic acid). For example, a single-molecule guide polynucleotide can be a single guide RNA (sgRNA or gRNA). Herein the term guide polynucleotide sequence contemplates any single, dual, or multi-molecule nucleic acid capable of interacting with and directing a base editor to a target polynucleotide sequence.

[0328] Typically, a guide polynucleotide (e.g., crRNA/trRNA complex or a gRNA) comprises a “polynucleotide-targeting segment” that includes a sequence capable of recognizing and binding to a target polynucleotide sequence, and a “protein-binding segment” that stabilizes the guide polynucleotide within a polynucleotide programmable nucleotide binding domain component of a base editor. In some embodiments, the polynucleotide targeting segment of the guide polynucleotide recognizes and binds to a DNA polynucleotide, thereby facilitating the editing of a base in DNA. In other cases, the polynucleotide targeting segment of the guide polynucleotide recognizes and binds to an RNA polynucleotide, thereby facilitating the editing of a base in RNA. Herein a “segment” refers to a section or region of a molecule, e.g., a contiguous stretch of nucleotides in the guide polynucleotide. A segment can also refer to a region/section of a complex such that a segment can comprise regions of more than one molecule. For example, where a guide polynucleotide comprises multiple nucleic acid molecules, the protein-binding segment of can include all or a portion of multiple separate molecules that are for instance hybridized along a region of complementarity. In some embodiments, a protein-binding segment of a DNA-targeting RNA that comprises two separate molecules can comprise (i) base pairs 40-75 of a first RNA molecule that is 100 base pairs in length; and (ii) base pairs 10-25 of a second RNA molecule that is 50 base pairs in length. The definition of “segment,” unless otherwise specifically defined in a particular context, is not limited to a specific number of total base pairs, is not limited to any particular number of base pairs from a given RNA molecule, is not limited to a particular number of separate molecules within a complex, and can include regions of RNA molecules that are of any total length and can include regions with complementarity to other molecules.

[0329] A guide RNA or a guide polynucleotide can comprise two or more RNAs, e.g., CRISPR RNA (crRNA) and transactivating crRNA (tracrRNA). A guide RNA or a guide polynucleotide can sometimes comprise a single-chain RNA, or single guide RNA (sgRNA) formed by fusion of a portion (e.g., a functional portion) of crRNA and tracrRNA. A guide RNA or a guide polynucleotide can also be a dual RNA comprising a crRNA and a tracrRNA. Furthermore, a crRNA can hybridize with a target DNA.

[0330] As discussed above, a guide RNA or a guide polynucleotide can be an expression product. For example, a DNA that encodes a guide RNA can be a vector comprising a sequence coding for the guide RNA. A guide RNA or a guide polynucleotide can be transferred into a cell by transfecting the cell with an isolated guide RNA or plasmid DNA comprising a sequence coding for the guide RNA and a promoter. A guide RNA or a guide polynucleotide can also be transferred into a cell in other way, such as using virus-mediated gene delivery.

[0331] A guide RNA or a guide polynucleotide can be isolated. For example, a guide RNA can be transfected in the form of an isolated RNA into a cell or organism. A guide RNA can be prepared by in vitro transcription using any in vitro transcription system known in the art. A guide RNA can be transferred to a cell in the form of isolated RNA rather than in the form of plasmid comprising encoding sequence for a guide RNA.

[0332] A guide RNA or a guide polynucleotide can comprise three regions: a first region at the 5′ end that can be complementary to a target site in a chromosomal sequence, a second internal region that can form a stem loop structure, and a third 3′ region that can be single-stranded. A first region of each guide RNA can also be different such that each guide RNA guides a fusion protein to a specific target site. Further, second and third regions of each guide RNA can be identical in all guide RNAs.

[0333] A first region of a guide RNA or a guide polynucleotide can be complementary to sequence at a target site in a chromosomal sequence such that the first region of the guide RNA can base pair with the target site. In some cases, a first region of a guide RNA can comprise from or from about 10 nucleotides to 25 nucleotides (i.e., from 10 nucleotides to nucleotides; or from about 10 nucleotides to about 25 nucleotides; or from 10 nucleotides to about 25 nucleotides; or from about 10 nucleotides to 25 nucleotides) or more. For example, a region of base pairing between a first region of a guide RNA and a target site in a chromosomal sequence can be or can be about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, or more nucleotides in length. Sometimes, a first region of a guide RNA can be or can be about 19, 20, or 21 nucleotides in length.

[0334] A guide RNA or a guide polynucleotide can also comprise a second region that forms a secondary structure. For example, a secondary structure formed by a guide RNA can comprise a stem (or hairpin) and a loop. A length of a loop and a stem can vary. For example, a loop can range from or from about 3 to 10 nucleotides in length, and a stem can range from or from about 6 to 20 base pairs in length. A stem can comprise one or more bulges of 1 to 10 or about 10 nucleotides. The overall length of a second region can range from or from about 16 to 60 nucleotides in length. For example, a loop can be or can be about 4 nucleotides in length and a stem can be or can be about 12 base pairs.

[0335] A guide RNA or a guide polynucleotide can also comprise a third region at the 3′ end that can be essentially single-stranded. For example, a third region is sometimes not complementarity to any chromosomal sequence in a cell of interest and is sometimes not complementarity to the rest of a guide RNA. Further, the length of a third region can vary. A third region can be more than or more than about 4 nucleotides in length. For example, the length of a third region can range from or from about 5 to 60 nucleotides in length.

[0336] A guide RNA or a guide polynucleotide can target any exon or intron of a gene target. In some cases, a guide can target exon 1 or 2 of a gene, in other cases; a guide can target exon 3 or 4 of a gene. A composition can comprise multiple guide RNAs that all target the same exon or in some cases, multiple guide RNAs that can target different exons. An exon and an intron of a gene can be targeted.

[0337] A guide RNA or a guide polynucleotide can target a nucleic acid sequence of or of about 20 nucleotides. A target nucleic acid can be less than or less than about 20 nucleotides. A target nucleic acid can be at least or at least about 5, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, or anywhere between 1-100 nucleotides in length. A target nucleic acid can be at most or at most about 5, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 40, 50, or anywhere between 1-100 nucleotides in length. A target nucleic acid sequence can be or can be about 20 bases immediately 5′ of the first nucleotide of the PAM. A guide RNA can target a nucleic acid sequence. A target nucleic acid can be at least or at least about 1-10, 1-20, 1-30, 1-40, 1-50, 1-60, 1-70, 1-80, 1-90, or 1-100 nucleotides.

[0338] A guide polynucleotide, for example, a guide RNA, can refer to a nucleic acid that can hybridize to another nucleic acid, for example, the target nucleic acid or protospacer in a genome of a cell. A guide polynucleotide can be RNA. A guide polynucleotide can be DNA. The guide polynucleotide can be programmed or designed to bind to a sequence of nucleic acid site-specifically. A guide polynucleotide can comprise a polynucleotide chain and can be called a single guide polynucleotide. A guide polynucleotide can comprise two polynucleotide chains and can be called a double guide polynucleotide. A guide RNA can be introduced into a cell or embryo as an RNA molecule. For example, a RNA molecule can be transcribed in vitro and/or can be chemically synthesized. An RNA can be transcribed from a synthetic DNA molecule, e.g., a gBlocks® gene fragment. A guide RNA can then be introduced into a cell or embryo as an RNA molecule. A guide RNA can also be introduced into a cell or embryo in the form of a non-RNA nucleic acid molecule, e.g., DNA molecule. For example, a DNA encoding a guide RNA can be operably linked to promoter control sequence for expression of the guide RNA in a cell or embryo of interest. A RNA coding sequence can be operably linked to a promoter sequence that is recognized by RNA polymerase III (Pol III). Plasmid vectors that can be used to express guide RNA include, but are not limited to, px330 vectors and px333 vectors. In some cases, a plasmid vector (e.g., px333 vector) can comprise at least two guide RNA-encoding DNA sequences.

[0339] Methods for selecting, designing, and validating guide polynucleotides, e.g., guide RNAs and targeting sequences are described herein and known to those skilled in the art. For example, to minimize the impact of potential substrate promiscuity of a deaminase domain in the nucleobase editor system (e.g., an AID domain), the number of residues that could unintentionally be targeted for deamination (e.g., off-target C residues that could potentially reside on ssDNA within the target nucleic acid locus) may be minimized. In addition, software tools can be used to optimize the gRNAs corresponding to a target nucleic acid sequence, e.g., to minimize total off-target activity across the genome. For example, for each possible targeting domain choice using S. pyogenes Cas9, all off-target sequences (preceding selected PAMs, e.g., NAG or NGG) may be identified across the genome that contain up to certain number (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) of mismatched base-pairs. First regions of gRNAs complementary to a target site can be identified, and all first regions (e.g., crRNAs) can be ranked according to its total predicted off-target score; the top-ranked targeting domains represent those that are likely to have the greatest on-target and the least off-target activity. Candidate targeting gRNAs can be functionally evaluated by using methods known in the art and/or as set forth herein.

[0340] As a non-limiting example, target DNA hybridizing sequences in crRNAs of a guide RNA for use with Cas9s may be identified using a DNA sequence searching algorithm. gRNA design may be carried out using custom gRNA design software based on the public tool cas-offinder as described in Bae S., Park J., & Kim J.-S. Cas-OFFinder: A fast and versatile algorithm that searches for potential off-target sites of Cas9 RNA-guided endonucleases. Bioinformatics 30, 1473-1475 (2014). This software scores guides after calculating their genome-wide off-target propensity. Typically matches ranging from perfect matches to 7 mismatches are considered for guides ranging in length from 17 to 24. Once the off-target sites are computationally-determined, an aggregate score is calculated for each guide and summarized in a tabular output using a web-interface. In addition to identifying potential target sites adjacent to PAM sequences, the software also identifies all PAM adjacent sequences that differ by 1, 2, 3 or more than 3 nucleotides from the selected target sites. Genomic DNA sequences for a target nucleic acid sequence, e.g., a target gene may be obtained and repeat elements may be screened using publically available tools, for example, the RepeatMasker program. RepeatMasker searches input DNA sequences for repeated elements and regions of low complexity. The output is a detailed annotation of the repeats present in a given query sequence.

[0341] Following identification, first regions of guide RNAs, e.g., crRNAs, may be ranked into tiers based on their distance to the target site, their orthogonality and presence of 5′ nucleotides for close matches with relevant PAM sequences (for example, a 5′ G based on identification of close matches in the human genome containing a relevant PAM e.g., NGG PAM for S. pyogenes, NNGRRT or NNGRRV PAM for S. aureus). As used herein, orthogonality refers to the number of sequences in the human genome that contain a minimum number of mismatches to the target sequence. A “high level of orthogonality” or “good orthogonality” may, for example, refer to 20-mer targeting domains that have no identical sequences in the human genome besides the intended target, nor any sequences that contain one or two mismatches in the target sequence. Targeting domains with good orthogonality may be selected to minimize off-target DNA cleavage.

[0342] In some embodiments, a reporter system may be used for detecting base-editing activity and testing candidate guide polynucleotides. In some embodiments, a reporter system may comprise a reporter gene based assay where base editing activity leads to expression of the reporter gene. For example, a reporter system may include a reporter gene comprising a deactivated start codon, e.g., a mutation on the template strand from 3′-TAC-5′ to 3′-CAC-5′. Upon successful deamination of the target C, the corresponding mRNA will be transcribed as 5′-AUG-3′ instead of 5′-GUG-3′, enabling the translation of the reporter gene. Suitable reporter genes will be apparent to those of skill in the art. Non-limiting examples of reporter genes include gene encoding green fluorescence protein (GFP), red fluorescence protein (RFP), luciferase, secreted alkaline phosphatase (SEAP), or any other gene whose expression are detectable and apparent to those skilled in the art. The reporter system can be used to test many different gRNAs, e.g., in order to determine which residue(s) with respect to the target DNA sequence the respective deaminase will target. sgRNAs that target non-template strand can also be tested in order to assess off-target effects of a specific base editing protein, e.g., a Cas9 deaminase fusion protein. In some embodiments, such gRNAs can be designed such that the mutated start codon will not be base-paired with the gRNA. The guide polynucleotides can comprise standard ribonucleotides, modified ribonucleotides (e.g., pseudouridine), ribonucleotide isomers, and/or ribonucleotide analogs. In some embodiments, the guide polynucleotide can comprise at least one detectable label. The detectable label can be a fluorophore (e.g., FAM, TMR, Cy3, Cy5, Texas Red, Oregon Green, Alexa Fluors, Halo tags, or suitable fluorescent dye), a detection tag (e.g., biotin, digoxigenin, and the like), quantum dots, or gold particles.

[0343] The guide polynucleotides can be synthesized chemically, synthesized enzymatically, or a combination thereof. For example, the guide RNA can be synthesized using standard phosphoramidite-based solid-phase synthesis methods. Alternatively, the guide RNA can be synthesized in vitro by operably linking DNA encoding the guide RNA to a promoter control sequence that is recognized by a phage RNA polymerase. Examples of suitable phage promoter sequences include T7, T3, SP6 promoter sequences, or variations thereof. In embodiments in which the guide RNA comprises two separate molecules (e.g., crRNA and tracrRNA), the crRNA can be chemically synthesized and the tracrRNA can be enzymatically synthesized.

[0344] In some embodiments, a base editor system may comprise multiple guide polynucleotides, e.g., gRNAs. For example, the gRNAs may target to one or more target loci (e.g., at least 1 gRNA, at least 2 gRNA, at least 5 gRNA, at least 10 gRNA, at least 20 gRNA, at least 30 g RNA, at least 50 gRNA) comprised in a base editor system. The multiple gRNA sequences can be tandemly arranged and are preferably separated by a direct repeat.

[0345] A DNA sequence encoding a guide RNA or a guide polynucleotide can also be part of a vector. Further, a vector can comprise additional expression control sequences (e.g., enhancer sequences, Kozak sequences, polyadenylation sequences, transcriptional termination sequences, etc.), selectable marker sequences (e.g., GFP or antibiotic resistance genes such as puromycin), origins of replication, and the like. A DNA molecule encoding a guide RNA (gRNA) can also be linear. A DNA molecule encoding a guide RNA (gRNA) or a guide polynucleotide can also be circular.

[0346] In some embodiments, one or more components of a base editor system may be encoded by DNA sequences. Such DNA sequences may be introduced into an expression system, e.g., a cell, together or separately. For example, DNA sequences encoding a polynucleotide programmable nucleotide binding domain and a guide RNA may be introduced into a cell, each DNA sequence can be part of a separate molecule (e.g., one vector containing the polynucleotide programmable nucleotide binding domain coding sequence and a second vector containing the guide RNA coding sequence) or both can be part of a same molecule (e.g., one vector containing coding (and regulatory) sequence for both the polynucleotide programmable nucleotide binding domain and the guide RNA).

[0347] A guide polynucleotide can comprise one or more modifications to provide a nucleic acid with a new or enhanced feature. A guide polynucleotide can comprise a nucleic acid affinity tag. A guide polynucleotide can comprise synthetic nucleotide, synthetic nucleotide analog, nucleotide derivatives, and/or modified nucleotides.

[0348] In some cases, a gRNA or a guide polynucleotide can comprise modifications. A modification can be made at any location of a gRNA or a guide polynucleotide. More than one modification can be made to a single gRNA or a guide polynucleotide. A gRNA or a guide polynucleotide can undergo quality control after a modification. In some cases, quality control can include PAGE, HPLC, MS, or any combination thereof.

[0349] A modification of a gRNA or a guide polynucleotide can be a substitution, insertion, deletion, chemical modification, physical modification, stabilization, purification, or any combination thereof.

[0350] A gRNA or a guide polynucleotide can also be modified by 5′adenylate, 5′ guanosine-triphosphate cap, 5′N7-Methylguanosine-triphosphate cap, 5′triphosphate cap, 3′phosphate, 3′thiophosphate, 5′phosphate, 5′thiophosphate, Cis-Syn thymidine dimer, trimers, C12 spacer, C3 spacer, C6 spacer, dSpacer, PC spacer, rSpacer, Spacer 18, Spacer 9,3′-3′ modifications, 5′-5′ modifications, abasic, acridine, azobenzene, biotin, biotin BB, biotin TEG, cholesteryl TEG, desthiobiotin TEG, DNP TEG, DNP-X, DOTA, dT-Biotin, dual biotin, PC biotin, psoralen C2, psoralen C6, TINA, 3′DABCYL, black hole quencher 1, black hole quencer 2, DABCYL SE, dT-DABCYL, IRDye QC-1, QSY-21, QSY-35, QSY-7, QSY-9, carboxyl linker, thiol linkers, 2′-deoxyribonucleoside analog purine, 2′-deoxyribonucleoside analog pyrimidine, ribonucleoside analog, 2′-O-methyl ribonucleoside analog, sugar modified analogs, wobble/universal bases, fluorescent dye label, 2′-fluoro RNA, 2′-O-methyl RNA, methylphosphonate, phosphodiester DNA, phosphodiester RNA, phosphothioate DNA, phosphorothioate RNA, UNA, pseudouridine-5′-triphosphate, 5′-methylcytidine-5′-triphosphate, or any combination thereof.

[0351] In some cases, a modification is permanent. In other cases, a modification is transient. In some cases, multiple modifications are made to a gRNA or a guide polynucleotide. A gRNA or a guide polynucleotide modification can alter physiochemical properties of a nucleotide, such as their conformation, polarity, hydrophobicity, chemical reactivity, base-pairing interactions, or any combination thereof.

[0352] The PAM sequence can be any PAM sequence known in the art. Suitable PAM sequences include, but are not limited to, NGG, NGA, NGC, NGN, NGT, NGCG, NGAG, NGAN, NGNG, NGCN, NGCG, NGTN, NNGRRT, NNNRRT, NNGRR(N), TTTV, TYCV, TYCV, TATV, NNNNGATT, NNAGAAW, or NAAAAC. Y is a pyrimidine; N is any nucleotide base; W is A or T.

[0353] A modification can also be a phosphorothioate substitute. In some cases, a natural phosphodiester bond can be susceptible to rapid degradation by cellular nucleases and; a modification of internucleotide linkage using phosphorothioate (PS) bond substitutes can be more stable towards hydrolysis by cellular degradation. A modification can increase stability in a gRNA or a guide polynucleotide. A modification can also enhance biological activity. In some cases, a phosphorothioate enhanced RNA gRNA can inhibit RNase A, RNase Ti, calf serum nucleases, or any combinations thereof. These properties can allow the use of PS-RNA gRNAs to be used in applications where exposure to nucleases is of high probability in vivo or in vitro. For example, phosphorothioate (PS) bonds can be introduced between the last 3-5 nucleotides at the 5′- or “-end of a gRNA which can inhibit exonuclease degradation. In some cases, phosphorothioate bonds can be added throughout an entire gRNA to reduce attack by endonucleases.

Protospacer Adjacent Motif

[0354] The term “protospacer adjacent motif (PAM)” or PAM-like motif refers to a 2-6 base pair DNA sequence immediately following the DNA sequence targeted by the Cas9 nuclease in the CRISPR bacterial adaptive immune system. In some embodiments, the PAM can be a 5′ PAM (i.e., located upstream of the 5′ end of the protospacer). In other embodiments, the PAM can be a 3′ PAM (i.e., located downstream of the 5′ end of the protospacer).

[0355] The PAM sequence is essential for target binding, but the exact sequence depends on a type of Cas protein.

[0356] A base editor provided herein can comprise a CRISPR protein-derived domain that is capable of binding a nucleotide sequence that contains a canonical or non-canonical protospacer adjacent motif (PAM) sequence. A PAM site is a nucleotide sequence in proximity to a target polynucleotide sequence. Some aspects of the disclosure provide for base editors comprising all or a portion of CRISPR proteins that have different PAM specificities. For example, typically Cas9 proteins, such as Cas9 from S. pyogenes (spCas9), require a canonical NGG PAM sequence to bind a particular nucleic acid region, where the “N” in “NGG” is adenine (A), thymine (T), guanine (G), or cytosine (C), and the G is guanine. A PAM can be CRISPR protein-specific and can be different between different base editors comprising different CRISPR protein-derived domains. A PAM can be 5′ or 3′ of a target sequence. A PAM can be upstream or downstream of a target sequence. A PAM can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more nucleotides in length. Often, a PAM is between 2-6 nucleotides in length. Several PAM variants are described in Table 1 below.

TABLE-US-00047 TABLE 1 Cas9 proteins and corresponding PAM sequences Variant PAM spCas9 NGG spCas9-VRQR NGA spCas9-VRER NGCG SpCas9-MQKFRAER NGC xCas9 (sp) NGN saCas9 NNGRRT saCas9-KKH NNNRRT spCas9-MQKSER NGCG spCas9-MQKSER NGCN spCas9-LRKIQK NGTN spCas9-LRVSQK NGTN spCas9-LRVSQL NGTN SpyMacCas9 NAA Cpf1 5′ (TTTV)

[0357] In some embodiments, the PAM is NGC. In some embodiments, the NGC PAM is recognized by a Cas9 variant. In some embodiments, the NGC PAM variant includes one or more amino acid substitutions selected from D1135M, S1136Q, G1218K, E1219F, A1322R, D1332A, R1335E, and T1337R (collectively termed “MQKFRAER”).

[0358] In some embodiments, the PAM is NGT. In some embodiments, the NGT PAM is a variant. In some embodiments, the NGT PAM variant is created through targeted mutations at one or more residues 1335, 1337, 1135, 1136, 1218, and/or 1219. In some embodiments, the NGT PAM variant is created through targeted mutations at one or more residues 1219, 1335, 1337, 1218. In some embodiments, the NGT PAM variant is created through targeted mutations at one or more residues 1135, 1136, 1218, 1219, and 1335. In some embodiments, the NGT PAM variant is selected from the set of targeted mutations provided in Tables 2 and 3 below.

TABLE-US-00048 TABLE 2 NGT PAM Variant Mutations at residues 1219, 1335, 1337, 1218 Variant E1219V R1335Q T1337 G1218  1 F V T  2 F V R  3 F V Q  4 F V L  5 F V T R  6 F V R R  7 F V Q R  8 F V L R  9 L L T 10 L L R 11 L L Q 12 L L L 13 F I T 14 F I R 15 F I Q 16 F I L 17 F G C 18 H L N 19 F G C A 20 H L N V 21 L A W 22 L A F 23 L A Y 24 I A W 25 I A F 26 I A Y

TABLE-US-00049 TABLE 3 NGT PAM Variant Mutations at residues 1135, 1136, 1218, 1219, and 1335 Variant D1135L S1136R G1218S E1219V R1335Q 27 G 28 V 29 I 30 A 31 W 32 H 33 K 34 K 35 R 36 Q 37 T 38 N 39 I 40 A 41 N 42 Q 43 G 44 L 45 S 46 T 47 L 48 I 49 V 50 N 51 S 52 T 53 F 54 Y 55 N1286Q I1331F

[0359] In some embodiments, the NGT PAM variant is selected from variant 5, 7, 28, 31, or 36 in Tables 2 and 3. In some embodiments, the variants have improved NGT PAM recognition.

[0360] In some embodiments, the NGT PAM variants have mutations at residues 1219, 1335, 1337, and/or 1218. In some embodiments, the NGT PAM variant is selected with mutations for improved recognition from the variants provided in Table 4 below.

TABLE-US-00050 TABLE 4 NGT PAM Variant Mutations at residues 1219, 1335, 1337, and 1218 Variant E1219V R1335Q T1337 G1218 1 F V T 2 F V R 3 F V Q 4 F V L 5 F V T R 6 F V R R 7 F V Q R 8 F V L R

[0361] In some embodiments, the NGT PAM is selected from the variants provided in Table 5 below.

TABLE-US-00051 TABLE 5 NGT PAM variants NGTN variant D1135 S1136 G1218 E1219 A1322R R1335 T1337 Variant 1 LRKIQK L R K I — Q K Variant 2 LRSVQK L R S V — Q K Variant 3 LRSVQL L R S V — Q L Variant 4 LRKIRQK L R K I R Q K Variant 5 LRSVRQK L R S V R Q K Variant 6 LRSVRQL L R S V R Q L

[0362] In some embodiments, the Cas9 domain is a Cas9 domain from Streptococcus pyogenes (SpCas9). In some embodiments, the SpCas9 domain is a nuclease active SpCas9, a nuclease inactive SpCas9 (SpCas9d), or a SpCas9 nickase (SpCas9n). In some embodiments, the SpCas9 comprises a D9X mutation, or a corresponding mutation in any of the amino acid sequences provided herein, wherein X is any amino acid except for D. In some embodiments, the SpCas9 comprises a D9A mutation, or a corresponding mutation in any of the amino acid sequences provided herein. In some embodiments, the SpCas9 domain, the SpCas9d domain, or the SpCas9n domain can bind to a nucleic acid sequence having a non-canonical PAM. In some embodiments, the SpCas9 domain, the SpCas9d domain, or the SpCas9n domain can bind to a nucleic acid sequence having an NGG, a NGA, or a NGCG PAM sequence.

[0363] In some embodiments, the SpCas9 domain comprises one or more of a D1135X, a R1335X, and a T1336X mutation, or a corresponding mutation in any of the amino acid sequences provided herein, wherein X is any amino acid. In some embodiments, the SpCas9 domain comprises one or more of a D1135E, R1335Q, and T1336R mutation, or a corresponding mutation in any of the amino acid sequences provided herein. In some embodiments, the SpCas9 domain comprises a D1135E, a R1335Q, and a T1336R mutation, or corresponding mutations in any of the amino acid sequences provided herein. In some embodiments, the SpCas9 domain comprises one or more of a D1135X, a R1335X, and a T1336X mutation, or a corresponding mutation in any of the amino acid sequences provided herein, wherein X is any amino acid. In some embodiments, the SpCas9 domain comprises one or more of a D1135V, a R1335Q, and a T1336R mutation, or a corresponding mutation in any of the amino acid sequences provided herein. In some embodiments, the SpCas9 domain comprises a D1135V, a R1335Q, and a T1336R mutation, or corresponding mutations in any of the amino acid sequences provided herein. In some embodiments, the SpCas9 domain comprises one or more of a D1135X, a G1217X, a R1335X, and a T1336X mutation, or a corresponding mutation in any of the amino acid sequences provided herein, wherein X is any amino acid. In some embodiments, the SpCas9 domain comprises one or more of a D1135V, a G1217R, a R1335Q, and a T1336R mutation, or a corresponding mutation in any of the amino acid sequences provided herein. In some embodiments, the SpCas9 domain comprises a D1135V, a G1217R, a R1335Q, and a T1336R mutation, or corresponding mutations in any of the amino acid sequences provided herein. In some embodiments, the SpCas9 domain comprises one or more of the amino acid substitutions as shown in FIGS. 3A-3C and FIG. 10.

[0364] In some embodiments, the Cas9 domains of any of the fusion proteins provided herein comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to a Cas9 polypeptide described herein. In some embodiments, the Cas9 domains of any of the fusion proteins provided herein comprises the amino acid sequence of any Cas9 polypeptide described herein. In some embodiments, the Cas9 domains of any of the fusion proteins provided herein consists of the amino acid sequence of any Cas9 polypeptide described herein.

[0365] In some examples, a PAM recognized by a CRISPR protein-derived domain of a base editor disclosed herein can be provided to a cell on a separate oligonucleotide to an insert (e.g., an AAV insert) encoding the base editor. In such embodiments, providing PAM on a separate oligonucleotide can allow cleavage of a target sequence that otherwise would not be able to be cleaved, because no adjacent PAM is present on the same polynucleotide as the target sequence.

[0366] In an embodiment, S. pyogenes Cas9 (SpCas9) can be used as a CRISPR endonuclease for genome engineering. However, others can be used. In some embodiments, a different endonuclease can be used to target certain genomic targets. In some embodiments, synthetic SpCas9-derived variants with non-NGG PAM sequences can be used. Additionally, other Cas9 orthologues from various species have been identified and these “non-SpCas9s” can bind a variety of PAM sequences that can also be useful for the present disclosure. For example, the relatively large size of SpCas9 (approximately 4 kb coding sequence) can lead to plasmids carrying the SpCas9 cDNA that cannot be efficiently expressed in a cell. Conversely, the coding sequence for Staphylococcus aureus Cas9 (SaCas9) is approximately 1 kilobase shorter than SpCas9, possibly allowing it to be efficiently expressed in a cell. Similar to SpCas9, the SaCas9 endonuclease is capable of modifying target genes in mammalian cells in vitro and in mice in vivo. In some embodiments, a Cas protein can target a different PAM sequence. In some embodiments, a target gene can be adjacent to a Cas9 PAM, 5′-NGG, for example. In some embodiments, a target gene can be adjacent to a Cas9 PAM, 5′-NGC or a Cas9 PAM comprising 5′-NGC, for example. In other embodiments, other Cas9 orthologs can have different PAM requirements. For example, other PAMs such as those of S. thermophilus (5′-NNAGAA for CRISPR1 and 5′-NGGNG for CRISPR3) and Neisseria meningiditis (5′-NNNNGATT) can also be found adjacent to a target gene.

[0367] In some embodiments, for a S. pyogenes system, a target gene sequence can precede (i.e., be 5′ to) a 5′-NGG PAM, and a 20-nt guide RNA sequence can base pair with an opposite strand to mediate a Cas9 cleavage adjacent to a PAM. In some embodiments, an adjacent cut can be or can be about 3 base pairs upstream of a PAM. In some embodiments, an adjacent cut can be or can be about 10 base pairs upstream of a PAM. In some embodiments, an adjacent cut can be or can be about 0-20 base pairs upstream of a PAM. For example, an adjacent cut can be next to, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 base pairs upstream of a PAM. An adjacent cut can also be downstream of a PAM by 1 to 30 base pairs. The sequences of exemplary SpCas9 proteins capable of binding a PAM sequence follow:

[0368] The amino acid sequence of an exemplary PAM-binding SpCas9 is as follows:

TABLE-US-00052 MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGAL LFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLE ESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRL IYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENPINAS GVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSN FDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDIL RVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKN GYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNG SIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGN SRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPNEKVLPK HSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTV KQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEEN EDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLS RKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDDSLTFKEDIQKAQVS GQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHKPENIVIEMAR ENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYL QNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKS DNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIK RQLVETRQITKHVAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKD FQFYKVREINNYHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRK MIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGE IVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIAR KKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSS FEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGN ELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISE FSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTMLGAPAAFKY FDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQLGGD.

[0369] The amino acid sequence of an exemplary PAM-binding SpCas9n is as follows:

TABLE-US-00053 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGAL LFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLE ESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRL IYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENPINAS GVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSN FDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDIL RVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKN GYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNG SIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGN SRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPNEKVLPK HSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTV KQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEEN EDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLS RKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDDSLTFKEDIQKAQVS GQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHKPENIVIEMAR ENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYL QNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKS DNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIK RQLVETRQITKHVAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKD FQFYKVREINNYHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRK MIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGE IVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIAR KKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSS FEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGN ELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISE FSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPAAFKY FDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQLGGD.

[0370] The amino acid sequence of an exemplary PAM-binding SpEQR Cas9 is as follows:

TABLE-US-00054 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGAL LFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLE ESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRL IYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENPINAS GVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSN FDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDIL RVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKN GYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNG SIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGN SRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPNEKVLPK HSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTV KQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEEN EDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLS RKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDDSLTFKEDIQKAQVS GQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHKPENIVIEMAR ENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYL QNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKS DNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIK RQLVETRQITKHVAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKD FQFYKVREINNYHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRK MIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGE IVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIAR KKDWDPKKYGGF SPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSS FEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGN ELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISE FSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPAAFKY FDTTIDRK Y STKEVLDATLIHQSITGLYETRIDLSQLGGD. In this sequence, residues E1135, Q1335 and R1337, which can be mutated from D1135, R1335. and T1337 to yield a SpEQR Cas9, are underlined and in bold.

[0371] The amino acid sequence of an exemplary PAM-binding SpVQR Cas9 is as follows:

TABLE-US-00055 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGAL LFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLE ESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRL IYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTYNQLFEENPINAS GVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGLTPNFKSN FDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDIL RVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKN GYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNG SIPHQIHLGELHAILRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGN SRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMTNFDKNLPNEKVLPK HSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTV KQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEEN EDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLS RKLINGIRDKQSGKTILDFLKSDGFANRNFMQLIHDDSLTFKEDIQKAQVS GQGDSLHEHIANLAGSPAIKKGILQTVKVVDELVKVMGRHKPENIVIEMAR ENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQNEKLYLYYL QNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKS DNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIK RQLVETRQITKHVAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKD FQFYKVREINNYHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRK MIAKSEQEIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGE IVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIAR KKDWDPKKYGGF SPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSS FEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGN ELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISE FSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPAAFKY FDTTIDRK Y STKEVLDATLIHQSITGLYETRIDLSQLGGD. In this sequence, residues V1135, Q1335, and R1336, which can be mutated from D1135, R1335, and T1336 to yield a SpVQR Cas9, are underlined and in bold.

[0372] The amino acid sequence of an exemplary PAM-binding SpVRER Cas9 is as follows:

TABLE-US-00056 MDKKYSIGLAIGTNSVGWAVITDEYKVPSKK FKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKV DDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIY LALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLS KSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLL AQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQ QLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQR TFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWM TRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKV KYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNA SLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQL KRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKEDIQKAQV SGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQK NSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYD VDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDN LTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSK LVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIA KSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRK VLSMPQVNIVKKTEVQTGGFSKESILPKRNS DKLIARKKDWDPKKYGGF SPTVAYSVLVVA KVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENG RKRMLASA ELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIE QISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDR K Y STKEVLDATLIHQSITGLYET RIDLSQLGQD

[0373] In some embodiments, the Cas9 domain is a recombinant Cas9 domain. In some embodiments, the recombinant Cas9 domain is a SpyMacCas9 domain. In some embodiments, the SpyMacCas9 domain is a nuclease active SpyMacCas9, a nuclease inactive SpyMacCas9 (SpyMacCas9d), or a SpyMacCas9 nickase (SpyMacCas9n). In some embodiments, the SaCas9 domain, the SaCas9d domain, or the SaCas9n domain can bind to a nucleic acid sequence having a non-canonical PAM. In some embodiments, the SpyMacCas9 domain, the SpCas9d domain, or the SpCas9n domain can bind to a nucleic acid sequence having a NAA PAM sequence.

TABLE-US-00057 Exemplary SpyMacCas9 MDKKYSIGLDIGTNSVGWAVITDDYKVPSKKFKVLG NTDRHSIKKNLIGALLFGSGETAEATRLKRTARRR YTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFL VEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKK LADSTDKADLRLIYLALAHMIKFRGHFLIEGDLNP DNSDVDKLFIQLVQIYNQLFEENPINASRVDAKAI LSARLSKSRRLENLIAQLPGEKRNGLFGNLIALSL GLTPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQ IGDQYADLFLAAKNLSDAILLSDILRVNSEITKAP LSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIF FDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGT EELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHA ILRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLA RGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSF IERMTNFDKNLPNEKVLPKHSLLYEYFTVYNELTK VKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRKVTV KQLKEDYFKKIECFDSVEISGVEDRFNASLGAYHD LLKIIKDKDFLDNEENEDILEDIVLTLTLFEDRGM IEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKL INGIRDKQSGKTILDFLKSDGFANRNFMQLIHDDS LTFKEDIQKAQVSGQGHSLHEQIANLAGSPAIKKG ILQTVKIVDELVKVMGHKPENIVIEMARENQTTQK GQKNSRERMKRIEEGIKELGSQILKEHPVENTQLQ NEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIV PQSFIKDDSIDNKVLTRSDKNRGKSDNVPSEEVVK KMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELD KAGFIKRQLVETRQITKHVAQILDSRMNTKYDEND KLIREVKVITLKSKLVSDFRKDFQFYKVREINNYH HAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYD VRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITL ANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVL SMPQVNIVKKTEIQTVGQNGGLFDDNPKSPLEVTP SKLVPLKKELNPKKYGGYQKPTTAYPVLLITDTKQ LIPISVMNKKQFEQNPVKFLRDRGYQQVGKNDFIK LPKYTLVDIGDGIKRLWASSKEIHKGNQLVVSKKS QILLYHAHHLDSDLSNDYLQNHNQQFDVLFNEIIS FSKKCKLGKEHIQKIENVYSNKKNSASIEELAESF IKLLGFTQLGATSPFNFLGVKLNQKQYKGKKDYIL PCTEGTLIRQSITGLYETRVDLSKIGED.

[0374] In some cases, a variant Cas9 protein harbors, H840A, P475A, W476A, N477A, D1125A, W1126A, and D1218A mutations such that the polypeptide has a reduced ability to cleave a target DNA or RNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA). As another non-limiting example, in some cases, the variant Cas9 protein harbors D10A, H840A, P475A, W476A, N477A, D1125A, W1126A, and D1218A mutations such that the polypeptide has a reduced ability to cleave a target DNA. Such a Cas9 protein has a reduced ability to cleave a target DNA (e.g., a single stranded target DNA) but retains the ability to bind a target DNA (e.g., a single stranded target DNA). In some cases, when a variant Cas9 protein harbors W476A and W1126A mutations or when the variant Cas9 protein harbors P475A, W476A, N477A, D1125A, W1126A, and D1218A mutations, the variant Cas9 protein does not bind efficiently to a PAM sequence. Thus, in some such cases, when such a variant Cas9 protein is used in a method of binding, the method does not require a PAM sequence. In other words, in some cases, when such a variant Cas9 protein is used in a method of binding, the method can include a guide RNA, but the method can be performed in the absence of a PAM sequence (and the specificity of binding is therefore provided by the targeting segment of the guide RNA). Other residues can be mutated to achieve the above effects (i.e., inactivate one or the other nuclease portions). As non-limiting examples, residues D10, G12, G17, E762, H840, N854, N863, H982, H983, A984, D986, and/or A987 can be altered (i.e., substituted). Also, mutations other than alanine substitutions are suitable.

[0375] In some embodiments, a CRISPR protein-derived domain of a base editor can comprise all or a portion of a Cas9 protein with a canonical PAM sequence (NGG). In other embodiments, a Cas9-derived domain of a base editor can employ a non-canonical PAM sequence. Such sequences have been described in the art and would be apparent to the skilled artisan. For example, Cas9 domains that bind non-canonical PAM sequences have been described in Kleinstiver, B. P., et al., “Engineered CRISPR-Cas9 nucleases with altered PAM specificities” Nature 523, 481-485 (2015); and Kleinstiver, B. P., et al., “Broadening the targeting range of Staphylococcus aureus CRISPR-Cas9 by modifying PAM recognition” Nature Biotechnology 33, 1293-1298 (2015); the entire contents of each are hereby incorporated by reference.

Fusion Proteins Comprising a Cas9 Domain and a Cytidine Deaminase and/or Adenosine Deaminase

[0376] Some aspects of the disclosure provide fusion proteins comprising a Cas9 domain or other nucleic acid programmable DNA binding protein and one or more adenosine deaminase domain, cytidine deaminase domain, and/or DNA glycosylase domains. It should be appreciated that the Cas9 domain may be any of the Cas9 domains or Cas9 proteins (e.g., dCas9 or nCas9) provided herein. In an embodiment, the Cas9 domain is an SpCas9 domain or an SpCas9 variant domain as described herein. In some embodiments, any of the Cas9 domains or Cas9 proteins (e.g., dCas9 or nCas9) provided herein may be fused with any of the cytidine deaminases and adenosine deaminases provided herein. The domains of the base editors disclosed herein can be arranged in any order.

[0377] For example, and without limitation, in some embodiments, the fusion protein comprises the structure:

NH.sub.2-[cytidine deaminase]-[Cas9 domain]-[adenosine deaminase]-COOH;
NH.sub.2-[adenosine deaminase]-[Cas9 domain]-[cytidine deaminase]-COOH;
NH.sub.2-[adenosine deaminase]-[cytidine deaminase]-[Cas9 domain]-COOH;
NH.sub.2-[cytidine deaminase]-[adenosine deaminase]-[Cas9 domain]-COOH;
NH.sub.2-[Cas9 domain]-[adenosine deaminase]-[cytidine deaminase]-COOH; or
NH.sub.2-[Cas9 domain]-[cytidine deaminase]-[adenosine deaminase]-COOH.

[0378] In some embodiments, the adenosine deaminase of the fusion protein comprises a TadA*8 and a cytidine deaminase. In some embodiments, the TadA*8 is TadA*8.1, TadA*8.2, TadA*8.3, TadA*8.4, TadA*8.5, TadA*8.6, TadA*8.7, TadA*8.8, TadA*8.9, TadA*8.10, TadA*8.11, TadA*8.12, TadA*8.13, TadA*8.14, TadA*8.15, TadA*8.16, TadA*8.17, TadA*8.18, TadA*8.19, TadA*8.20, TadA*8.21, TadA*8.22, TadA*8.23, or TadA*8.24.

[0379] Exemplary fusion protein structures include the following:

NH.sub.2-[adenosine deaminase]-[Cas9]-[cytidine deaminase]-COOH;
NH.sub.2-[cytidine deaminase]-[Cas9]-[adenosine deaminase]-COOH;
NH.sub.2-[TadA*8]-[Cas9]-[cytidine deaminase]-COOH; or
NH.sub.2-[cytidine deaminase]-[Cas9]-[TadA*8]-COOH.

[0380] In some embodiments, the fusion proteins comprising a cytidine deaminase, abasic editor, and adenosine deaminase and a napDNAbp (e.g., Cas9 domain) do not include a linker sequence. In some embodiments, a linker is present between the cytidine deaminase and adenosine deaminase domains and the napDNAbp. In some embodiments, the “-” used in the general architecture above indicates the presence of an optional linker. In some embodiments, the cytidine deaminase and adenosine deaminase and the napDNAbp are fused via any of the linkers provided herein. For example, in some embodiments the cytidine deaminase and adenosine deaminase and the napDNAbp are fused via any of the linkers provided below in the section entitled “Linkers”.

[0381] In some embodiments, the general architecture of exemplary Cas9 or Cas12 fusion proteins with a cytidine deaminase, adenosine deaminase and a Cas9 or Cas12 domain comprises any one of the following structures, where NLS is a nuclear localization sequence (e.g., any NLS provided herein), NH.sub.2 is the N-terminus of the fusion protein, and COOH is the C-terminus of the fusion protein.

[0382] NH.sub.2-NLS-[cytidine deaminase]-[Cas9 domain]-[adenosine deaminase]-COOH;

[0383] NH.sub.2-NLS-[adenosine deaminase]-[Cas9 domain]-[cytidine deaminase]-COOH;

[0384] NH.sub.2-NLS-[adenosine deaminase] [cytidine deaminase]-[Cas9 domain]-COOH;

[0385] NH.sub.2-NLS-[cytidine deaminase]-[adenosine deaminase]-[Cas9 domain]-COOH;

[0386] NH.sub.2-NLS-[Cas9 domain]-[adenosine deaminase]-[cytidine deaminase]-COOH;

[0387] NH.sub.2-NLS-[Cas9 domain]-[cytidine deaminase]-[adenosine deaminase]-COOH;

[0388] NH.sub.2-[cytidine deaminase]-[Cas9 domain]-[adenosine deaminase]-NLS—COOH;

[0389] NH.sub.2-[adenosine deaminase]-[Cas9 domain]-[cytidine deaminase]-NL2-COOH;

[0390] NH.sub.2-[adenosine deaminase] [cytidine deaminase]-[Cas9 domain]-NLS—COOH;

[0391] NH.sub.2-[cytidine deaminase]-[adenosine deaminase]-[Cas9 domain]-NLS—COOH;

[0392] NH.sub.2-[Cas9 domain]-[adenosine deaminase]-[cytidine deaminase]-NLS—COOH; or

[0393] NH.sub.2-[Cas9 domain]-[cytidine deaminase]-[adenosine deaminase]-NLS—COOH.

[0394] In some embodiments, the NLS is present in a linker or the NLS is flanked by linkers, for example described herein. In some embodiments, the N-terminus or C-terminus NLS is a bipartite NLS. A bipartite NLS comprises two basic amino acid clusters, which are separated by a relatively short spacer sequence (hence bipartite—2 parts, while monopartite NLSs are not). The NLS of nucleoplasmin, KR[PAATKKAGQA]KKKK, is the prototype of the ubiquitous bipartite signal: two clusters of basic amino acids, separated by a spacer of about 10 amino acids. The sequence of an exemplary bipartite NLS follows:

TABLE-US-00058 PKKKRKVEGADKRTADGSEFESPKKKRKV.

[0395] In some embodiments, the fusion proteins comprising a cytidine deaminase, adenosine deaminase, a Cas9 domain and an NLS do not comprise a linker sequence. In some embodiments, linker sequences between one or more of the domains or proteins (e.g., cytidine deaminase, adenosine deaminase, Cas9 domain or NLS) are present.

[0396] It should be appreciated that the fusion proteins of the present disclosure may comprise one or more additional features. For example, in some embodiments, the fusion protein may comprise inhibitors, cytoplasmic localization sequences, export sequences, such as nuclear export sequences, or other localization sequences, as well as sequence tags that are useful for solubilization, purification, or detection of the fusion proteins. Suitable protein tags provided herein include, but are not limited to, biotin carboxylase carrier protein (BCCP) tags, myc-tags, calmodulin-tags, FLAG-tags, hemagglutinin (HA)-tags, polyhistidine tags, also referred to as histidine tags or His-tags, maltose binding protein (MBP)-tags, nus-tags, glutathione-S-transferase (GST)-tags, green fluorescent protein (GFP)-tags, thioredoxin-tags, S-tags, Softags (e.g., Softag 1, Softag 3), strep-tags, biotin ligase tags, FlAsH tags, V5 tags, and SBP-tags. Additional suitable sequences will be apparent to those of skill in the art. In some embodiments, the fusion protein comprises one or more His tags.

[0397] Exemplary, yet nonlimiting, fusion proteins are described in International PCT Application Nos. PCT/2017/044935 and PCT/US2020/016288, each of which is incorporated herein by reference for its entirety.

Fusion Proteins Comprising a Nuclear Localization Sequence (NLS)

[0398] In some embodiments, the fusion proteins provided herein further comprise one or more (e.g., 2, 3, 4, 5) nuclear targeting sequences, for example a nuclear localization sequence (NLS). In one embodiment, a bipartite NLS is used. In some embodiments, a NLS comprises an amino acid sequence that facilitates the importation of a protein, that comprises an NLS, into the cell nucleus (e.g., by nuclear transport). In some embodiments, any of the fusion proteins provided herein further comprise a nuclear localization sequence (NLS). In some embodiments, the NLS is fused to the N-terminus of the fusion protein. In some embodiments, the NLS is fused to the C-terminus of the fusion protein. In some embodiments, the NLS is fused to the N-terminus of the Cas9 domain. In some embodiments, the NLS is fused to the C-terminus of an nCas9 domain or a dCas9 domain. In some embodiments, the NLS is fused to the N-terminus of the deaminase. In some embodiments, the NLS is fused to the C-terminus of the deaminase. In some embodiments, the NLS is fused to the fusion protein via one or more linkers. In some embodiments, the NLS is fused to the fusion protein without a linker. In some embodiments, the NLS comprises an amino acid sequence of any one of the NLS sequences provided or referenced herein. Additional nuclear localization sequences are known in the art and would be apparent to the skilled artisan. For example, NLS sequences are described in Plank et al., PCT/EP2000/011690, the contents of which are incorporated herein by reference for their disclosure of exemplary nuclear localization sequences. In some embodiments, an NLS comprises the amino acid sequence PKKKRKVEGADKRTADGSEFESPKKKRKV, KRTADGSEFESPKKKRKV, KRPAATKKAGQAKKKK, KKTELQTTNAENKTKKL, KRGINDRNFWRGENGRKTR, RKSGKIAAIVVKRPRKPKKKRKV, or MDSLLMNRRKFLYQFKNVRWAKGRRETYLC. In some embodiments, the NLS is present in a linker or the NLS is flanked by linkers, for example, the linkers described herein. In some embodiments, the N-terminus or C-terminus NLS is a bipartite NLS. A bipartite NLS comprises two basic amino acid clusters, which are separated by a relatively short spacer sequence (hence bipartite—2 parts, while monopartite NLSs are not). The NLS of nucleoplasmin, KR[PAATKKAGQA]KKKK, is the prototype of the ubiquitous bipartite signal: two clusters of basic amino acids, separated by a spacer of about 10 amino acids. The sequence of an exemplary bipartite NLS follows: PKKKRKVEGADKRTADGSEFES PKKKRKV.

[0399] In some embodiments, the fusion proteins of the invention do not comprise a linker sequence. In some embodiments, linker sequences between one or more of the domains or proteins are present. In some embodiments, the general architecture of exemplary Cas9 fusion proteins with an adenosine deaminase or a cytidine deaminase and a Cas9 domain comprises any one of the following structures, where NLS is a nuclear localization sequence (e.g., any NLS provided herein), NH.sub.2 is the N-terminus of the fusion protein, and COOH is the C-terminus of the fusion protein:

[0400] NH.sub.2-NLS-[adenosine deaminase]-[Cas9 domain]-COOH;

[0401] NH.sub.2-NLS [Cas9 domain]-[adenosine deaminase]-COOH;

[0402] NH.sub.2-[adenosine deaminase]-[Cas9 domain]-NLS—COOH;

[0403] NH.sub.2-[Cas9 domain]-[adenosine deaminase]-NLS—COOH;

[0404] NH.sub.2-NLS-[cytidine deaminase]-[Cas9 domain]-COOH;

[0405] NH.sub.2-NLS [Cas9 domain]-[cytidine deaminase]-COOH;

[0406] NH.sub.2-[cytidine deaminase]-[Cas9 domain]-NLS—COOH; or

[0407] NH.sub.2-[Cas9 domain]-[cytidine deaminase]-NLS—COOH.

[0408] It should be appreciated that the fusion proteins of the present disclosure may comprise one or more additional features. For example, in some embodiments, the fusion protein may comprise inhibitors, cytoplasmic localization sequences, export sequences, such as nuclear export sequences, or other localization sequences, as well as sequence tags that are useful for solubilization, purification, or detection of the fusion proteins. Suitable protein tags provided herein include, but are not limited to, biotin carboxylase carrier protein (BCCP) tags, myc-tags, calmodulin-tags, FLAG-tags, hemagglutinin (HA)-tags, polyhistidine tags, also referred to as histidine tags or His-tags, maltose binding protein (MBP)-tags, nus-tags, glutathione-S-transferase (GST)-tags, green fluorescent protein (GFP)-tags, thioredoxin-tags, S-tags, Softags (e.g., Softag 1, Softag 3), strep-tags, biotin ligase tags, FlAsH tags, V5 tags, and SBP-tags. Additional suitable sequences will be apparent to those of skill in the art. In some embodiments, the fusion protein comprises one or more His tags.

[0409] A vector that encodes a CRISPR enzyme comprising one or more nuclear localization sequences (NLSs) can be used. For example, there can be or be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 NLSs used. A CRISPR enzyme can comprise the NLSs at or near the ammo-terminus, about or more than about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 NLSs at or near the carboxy-terminus, or any combination of these (e.g., one or more NLS at the ammo-terminus and one or more NLS at the carboxy terminus). When more than one NLS is present, each can be selected independently of others, such that a single NLS can be present in more than one copy and/or in combination with one or more other NLSs present in one or more copies.

[0410] CRISPR enzymes used in the methods can comprise about 6 NLSs. An NLS is considered near the N- or C-terminus when the nearest amino acid to the NLS is within about 50 amino acids along a polypeptide chain from the N- or C-terminus, e.g., within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, or 50 amino acids.

Fusion Proteins with Internal Insertions

[0411] Provided herein are fusion proteins comprising a heterologous polypeptide fused to a nucleic acid programmable nucleic acid binding protein, for example, a napDNAbp. A heterologous polypeptide can be a polypeptide that is not found in the native or wild-type napDNAbp polypeptide sequence. The heterologous polypeptide can be fused to the napDNAbp at a C-terminal end of the napDNAbp, an N-terminal end of the napDNAbp, or inserted at an internal location of the napDNAbp. In some embodiments, the heterologous polypeptide is inserted at an internal location of the napDNAbp.

[0412] In some embodiments, the heterologous polypeptide is a deaminase or a functional fragment thereof. For example, a fusion protein can comprise a deaminase flanked by an N-terminal fragment and a C-terminal fragment of a Cas9 or Cas12 (e.g., Cas12b/C2c1), polypeptide. The deaminase in a fusion protein can be an adenosine deaminase. In some embodiments, the adenosine deaminase is a TadA (e.g., TadA7.10 or TadA*8). In some embodiments, the TadA is a TadA*8. TadA sequences (e.g., TadA7.10 or TadA*8) as described herein are suitable deaminases for the above-described fusion proteins.

[0413] The deaminase can be a circular permutant deaminase. For example, the deaminase can be a circular permutant adenosine deaminase. In some embodiments, the deaminase is a circular permutant TadA, circularly permutated at amino acid residue 116 as numbered in the TadA reference sequence. In some embodiments, the deaminase is a circular permutant TadA, circularly permutated at amino acid residue 136 as numbered in the TadA reference sequence. In some embodiments, the deaminase is a circular permutant TadA, circularly permutated at amino acid residue 65 as numbered in the TadA reference sequence.

[0414] The fusion protein can comprise more than one deaminase. The fusion protein can comprise, for example, 1, 2, 3, 4, 5 or more deaminases. In some embodiments, the fusion protein comprises one deaminase. In some embodiments, the fusion protein comprises two deaminases. The two or more deaminases in a fusion protein can be an adenosine deaminase. cytidine deaminase, or a combination thereof. The two or more deaminases can be homodimers. The two or more deaminases can be heterodimers. The two or more deaminases can be inserted in tandem in the napDNAbp. In some embodiments, the two or more deaminases may not be in tandem in the napDNAbp.

[0415] In some embodiments, the napDNAbp in the fusion protein is a Cas9 polypeptide or a fragment thereof. The Cas9 polypeptide can be a variant Cas9 polypeptide. In some embodiments, the Cas9 polypeptide is a Cas9 nickase (nCas9) polypeptide or a fragment thereof. In some embodiments, the Cas9 polypeptide is a nuclease dead Cas9 (dCas9) polypeptide or a fragment thereof. The Cas9 polypeptide in a fusion protein can be a full-length Cas9 polypeptide. In some cases, the Cas9 polypeptide in a fusion protein may not be a full length Cas9 polypeptide. The Cas9 polypeptide can be truncated, for example, at a N-terminal or C-terminal end relative to a naturally-occurring Cas9 protein. The Cas9 polypeptide can be a circularly permuted Cas9 protein. The Cas9 polypeptide can be a fragment, a portion, or a domain of a Cas9 polypeptide, that is still capable of binding the target polynucleotide and a guide nucleic acid sequence.

[0416] In some embodiments, the Cas9 polypeptide is a Streptococcus pyogenes Cas9 (SpCas9), Staphylococcus aureus Cas9 (SaCas9), Streptococcus thermophilus 1 Cas9 (St1Cas9), or fragments or variants thereof.

[0417] The Cas9 polypeptide of a fusion protein can comprise an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to a naturally-occurring Cas9 polypeptide.

[0418] The Cas9 polypeptide of a fusion protein can comprise an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to the Cas9 amino acid sequence set forth below (called the “Cas9 reference sequence” below):

TABLE-US-00059 MDKKYSIGLDIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAEAT RLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVD EVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFI QLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSLGL TPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRVNT EITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQEEF YKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLK DNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIERMT NFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTNRK VTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILEDIV LTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDF LKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVKVV DELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENTQL QNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGKSD NVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKH VAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNIMNFFKTEITLAN GEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNS DKLIARKKDWDPKKYGGFDSPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAGELQKGNELALPSKYVNFLYLAS HYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPI REQAENIIHLFTLTNLGAPAAFKYFDTTIDRKRYTSTKEVLDATLIHQSITGLYETRIDLSQ LGGD (single underline: HNH domain; double underline: RuvC domain).

[0419] Fusion proteins comprising a heterologous catalytic domain flanked by N- and C-terminal fragments of a Cas9 polypeptide are also useful for base editing in the methods as described herein. Fusion proteins comprising Cas9 and one or more deaminase domains, e.g., adenosine deaminase, or comprising an adenosine deaminase domain flanked by Cas9 sequences are also useful for highly specific and efficient base editing of target sequences. In an embodiment, a chimeric Cas9 fusion protein contains a heterologous catalytic domain (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) inserted within a Cas9 polypeptide. In some embodiments, the fusion protein comprises an adenosine deaminase domain and a cytidine deaminase domain inserted within a Cas9. In some embodiments, an adenosine deaminase is fused within a Cas9 and a cytidine deaminase is fused to the C-terminus. In some embodiments, an adenosine deaminase is fused within Cas9 and a cytidine deaminase fused to the N-terminus. In some embodiments, a cytidine deaminase is fused within Cas9 and an adenosine deaminase is fused to the C-terminus. In some embodiments, a cytidine deaminase is fused within Cas9 and an adenosine deaminase fused to the N-terminus.

[0420] Exemplary structures of a fusion protein with an adenosine deaminase and a cytidine deaminase and a Cas9 are provided as follows:

[0421] NH.sub.2-[Cas9(adenosine deaminase)]-[cytidine deaminase]-COOH;

[0422] NH.sub.2-[cytidine deaminase]-[Cas9(adenosine deaminase)]-COOH;

[0423] NH.sub.2-[Cas9(cytidine deaminase)]-[adenosine deaminase]-COOH; or

[0424] NH.sub.2-[adenosine deaminase]-[Cas9(cytidine deaminase)]-COOH.

[0425] In some embodiments, the “-” used in the general architecture above indicates the presence of an optional linker.

[0426] In various embodiments, the catalytic domain has DNA modifying activity (e.g., deaminase activity), such as adenosine deaminase activity. In some embodiments, the adenosine deaminase is a TadA (e.g., TadA7.10). In some embodiments, the TadA is a TadA*8. In some embodiments, a TadA*8 is fused within Cas9 and a cytidine deaminase is fused to the C-terminus. In some embodiments, a TadA*8 is fused within Cas9 and a cytidine deaminase fused to the N-terminus. In some embodiments, a cytidine deaminase is fused within Cas9 and a TadA*8 is fused to the C-terminus. In some embodiments, a cytidine deaminase is fused within Cas9 and a TadA*8 fused to the N-terminus. Exemplary structures of a fusion protein with a TadA*8 and a cytidine deaminase and a Cas9 are provided as follows:

[0427] NH.sub.2-[Cas9(TadA*8)]-[cytidine deaminase]-COOH;

[0428] NH.sub.2-[cytidine deaminase]-[Cas9(TadA*8)]-COOH;

[0429] NH.sub.2-[Cas9(cytidine deaminase)]-[TadA*8]-COOH; or

[0430] NH.sub.2-[TadA*8]-[Cas9(cytidine deaminase)]-COOH.

In some embodiments, the “-” used in the general architecture above indicates the presence of an optional linker.

[0431] The heterologous polypeptide (e.g., deaminase) can be inserted in the napDNAbp (e.g., Cas9 or Cas12 (e.g., Cas12b/C2c1)) at a suitable location, for example, such that the napDNAbp retains its ability to bind the target polynucleotide and a guide nucleic acid. A deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) can be inserted into a napDNAbp without compromising function of the deaminase (e.g., base editing activity) or the napDNAbp (e.g., ability to bind to target nucleic acid and guide nucleic acid). A deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) can be inserted in the napDNAbp at, for example, a disordered region or a region comprising a high temperature factor or B-factor as shown by crystallographic studies. Regions of a protein that are less ordered, disordered, or unstructured, for example solvent exposed regions and loops, can be used for insertion without compromising structure or function. A deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) can be inserted in the napDNAbp in a flexible loop region or a solvent-exposed region. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted in a flexible loop of the Cas9 or the Cas12b/C2c1 polypeptide.

[0432] In some embodiments, the insertion location of a deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is determined by B-factor analysis of the crystal structure of Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted in regions of the Cas9 polypeptide comprising higher than average B-factors (e.g., higher B factors compared to the total protein or the protein domain comprising the disordered region). B-factor or temperature factor can indicate the fluctuation of atoms from their average position (for example, as a result of temperature-dependent atomic vibrations or static disorder in a crystal lattice). A high B-factor (e.g., higher than average B-factor) for backbone atoms can be indicative of a region with relatively high local mobility. Such a region can be used for inserting a deaminase without compromising structure or function. A deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) can be inserted at a location with a residue having a Ca atom with a B-factor that is 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200%, or greater than 200% more than the average B-factor for the total protein. A deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) can be inserted at a location with a residue having a Ca atom with a B-factor that is 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200% or greater than 200% more than the average B-factor for a Cas9 protein domain comprising the residue. Cas9 polypeptide positions comprising a higher than average B-factor can include, for example, residues 768, 792, 1052, 1015, 1022, 1026, 1029, 1067, 1040, 1054, 1068, 1246, 1247, and 1248 as numbered in the above Cas9 reference sequence. Cas9 polypeptide regions comprising a higher than average B-factor can include, for example, residues 792-872, 792-906, and 2-791 as numbered in the above Cas9 reference sequence.

[0433] A heterologous polypeptide (e.g., deaminase) can be inserted in the napDNAbp at an amino acid residue selected from the group consisting of: 768, 791, 792, 1015, 1016, 1022, 1023, 1026, 1029, 1040, 1052, 1054, 1067, 1068, 1069, 1246, 1247, and 1248 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the heterologous polypeptide is inserted between amino acid positions 768-769, 791-792, 792-793, 1015-1016, 1022-1023, 1026-1027, 1029-1030, 1040-1041, 1052-1053, 1054-1055, 1067-1068, 1068-1069, 1247-1248, or 1248-1249 as numbered in the above Cas9 reference sequence or corresponding amino acid positions thereof. In some embodiments, the heterologous polypeptide is inserted between amino acid positions 769-770, 792-793, 793-794, 1016-1017, 1023-1024, 1027-1028, 1030-1031, 1041-1042, 1053-1054, 1055-1056, 1068-1069, 1069-1070, 1248-1249, or 1249-1250 as numbered in the above Cas9 reference sequence or corresponding amino acid positions thereof. In some embodiments, the heterologous polypeptide replaces an amino acid residue selected from the group consisting of: 768, 791, 792, 1015, 1016, 1022, 1023, 1026, 1029, 1040, 1052, 1054, 1067, 1068, 1069, 1246, 1247, and 1248 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. It should be understood that the reference to the above Cas9 reference sequence with respect to insertion positions is for illustrative purposes. The insertions as discussed herein are not limited to the Cas9 polypeptide sequence of the above Cas9 reference sequence, but include insertion at corresponding locations in variant Cas9 polypeptides, for example a Cas9 nickase (nCas9), nuclease dead Cas9 (dCas9), a Cas9 variant lacking a nuclease domain, a truncated Cas9, or a Cas9 domain lacking partial or complete HNH domain.

[0434] A heterologous polypeptide (e.g., deaminase) can be inserted in the napDNAbp at an amino acid residue selected from the group consisting of: 768, 792, 1022, 1026, 1040, 1068, and 1247 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the heterologous polypeptide is inserted between amino acid positions 768-769, 792-793, 1022-1023, 1026-1027, 1029-1030, 1040-1041, 1068-1069, or 1247-1248 as numbered in the above Cas9 reference sequence or corresponding amino acid positions thereof. In some embodiments, the heterologous polypeptide is inserted between amino acid positions 769-770, 793-794, 1023-1024, 1027-1028, 1030-1031, 1041-1042, 1069-1070, or 1248-1249 as numbered in the above Cas9 reference sequence or corresponding amino acid positions thereof. In some embodiments, the heterologous polypeptide replaces an amino acid residue selected from the group consisting of: 768, 792, 1022, 1026, 1040, 1068, and 1247 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0435] A heterologous polypeptide (e.g., deaminase) can be inserted in the napDNAbp at an amino acid residue as described herein, or a corresponding amino acid residue in another Cas9 polypeptide. In an embodiment, a heterologous polypeptide (e.g., deaminase) can be inserted in the napDNAbp at an amino acid residue selected from the group consisting of: 1002, 1003, 1025, 1052-1056, 1242-1247, 1061-1077, 943-947, 686-691, 569-578, 530-539, and 1060-1077 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. The deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) can be inserted at the N-terminus or the C-terminus of the residue or replace the residue. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of the residue.

[0436] In some embodiments, an adenosine deaminase (e.g., TadA) is inserted at an amino acid residue selected from the group consisting of: 1015, 1022, 1029, 1040, 1068, 1247, 1054, 1026, 768, 1067, 1248, 1052, and 1246 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, an adenosine deaminase (e.g., TadA) is inserted in place of residues 792-872, 792-906, or 2-791 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the adenosine deaminase is inserted at the N-terminus of an amino acid selected from the group consisting of: 1015, 1022, 1029, 1040, 1068, 1247, 1054, 1026, 768, 1067, 1248, 1052, and 1246 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the adenosine deaminase is inserted at the C-terminus of an amino acid selected from the group consisting of: 1015, 1022, 1029, 1040, 1068, 1247, 1054, 1026, 768, 1067, 1248, 1052, and 1246 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the adenosine deaminase is inserted to replace an amino acid selected from the group consisting of: 1015, 1022, 1029, 1040, 1068, 1247, 1054, 1026, 768, 1067, 1248, 1052, and 1246 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0437] In some embodiments, a CBE (e.g., APOBEC1) is inserted at an amino acid residue selected from the group consisting of: 1016, 1023, 1029, 1040, 1069, and 1247 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the ABE is inserted at the N-terminus of an amino acid selected from the group consisting of: 1016, 1023, 1029, 1040, 1069, and 1247 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the ABE is inserted at the C-terminus of an amino acid selected from the group consisting of: 1016, 1023, 1029, 1040, 1069, and 1247 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the ABE is inserted to replace an amino acid selected from the group consisting of: 1016, 1023, 1029, 1040, 1069, and 1247 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0438] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 768 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 768 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid residue 768 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid residue 768 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0439] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 791 or is inserted at amino acid residue 792, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 791 or is inserted at the N-terminus of amino acid 792, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid 791 or is inserted at the N-terminus of amino acid 792, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid 791, or is inserted to replace amino acid 792, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0440] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 1016 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 1016 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid residue 1016 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid residue 1016 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0441] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 1022, or is inserted at amino acid residue 1023, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 1022 or is inserted at the N-terminus of amino acid residue 1023, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid residue 1022 or is inserted at the C-terminus of amino acid residue 1023, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid residue 1022, or is inserted to replace amino acid residue 1023, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0442] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 1026, or is inserted at amino acid residue 1029, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 1026 or is inserted at the N-terminus of amino acid residue 1029, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid residue 1026 or is inserted at the C-terminus of amino acid residue 1029, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid residue 1026, or is inserted to replace amino acid residue 1029, as numbered in the above Cas9 reference sequence, or corresponding amino acid residue in another Cas9 polypeptide.

[0443] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 1040 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 1040 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid residue 1040 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid residue 1040 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0444] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 1052, or is inserted at amino acid residue 1054, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 1052 or is inserted at the N-terminus of amino acid residue 1054, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid residue 1052 or is inserted at the C-terminus of amino acid residue 1054, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid residue 1052, or is inserted to replace amino acid residue 1054, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0445] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 1067, or is inserted at amino acid residue 1068, or is inserted at amino acid residue 1069, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 1067 or is inserted at the N-terminus of amino acid residue 1068 or is inserted at the N-terminus of amino acid residue 1069, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid residue 1067 or is inserted at the C-terminus of amino acid residue 1068 or is inserted at the C-terminus of amino acid residue 1069, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid residue 1067, or is inserted to replace amino acid residue 1068, or is inserted to replace amino acid residue 1069, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0446] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at amino acid residue 1246, or is inserted at amino acid residue 1247, or is inserted at amino acid residue 1248, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the N-terminus of amino acid residue 1246 or is inserted at the N-terminus of amino acid residue 1247 or is inserted at the N-terminus of amino acid residue 1248, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted at the C-terminus of amino acid residue 1246 or is inserted at the C-terminus of amino acid residue 1247 or is inserted at the C-terminus of amino acid residue 1248, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) is inserted to replace amino acid residue 1246, or is inserted to replace amino acid residue 1247, or is inserted to replace amino acid residue 1248, as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0447] In some embodiments, a heterologous polypeptide (e.g., deaminase) is inserted in a flexible loop of a Cas9 polypeptide. The flexible loop portions can be selected from the group consisting of 530-537, 569-570, 686-691, 943-947, 1002-1025, 1052-1077, 1232-1247, or 1298-1300 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. The flexible loop portions can be selected from the group consisting of: 1-529, 538-568, 580-685, 692-942, 948-1001, 1026-1051, 1078-1231, or 1248-1297 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0448] A heterologous polypeptide (e.g., adenine deaminase) can be inserted into a Cas9 polypeptide region corresponding to amino acid residues: 1017-1069, 1242-1247, 1052-1056, 1060-1077, 1002-1003, 943-947, 530-537, 568-579, 686-691, 1242-1247, 1298-1300, 1066-1077, 1052-1056, or 1060-1077 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0449] A heterologous polypeptide (e.g., adenine deaminase) can be inserted in place of a deleted region of a Cas9 polypeptide. The deleted region can correspond to an N-terminal or C-terminal portion of the Cas9 polypeptide. In some embodiments, the deleted region corresponds to residues 792-872 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deleted region corresponds to residues 792-906 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deleted region corresponds to residues 2-791 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. In some embodiments, the deleted region corresponds to residues 1017-1069 as numbered in the above Cas9 reference sequence, or corresponding amino acid residues thereof.

[0450] Exemplary internal fusions base editors are provided in Table A below:

TABLE-US-00060 TABLE A Insertion loci in Cas9 proteins BE ID Modification Other ID IBE001 Cas9 TadA ins 1015 ISLAY01 IBE002 Cas9 TadA ins 1022 ISLAY02 IBE003 Cas9 TadA ins 1029 ISLAY03 IBE004 Cas9 TadA ins 1040 ISLAY04 IBE005 Cas9 TadA ins 1068 ISLAY05 IBE006 Cas9 TadA ins 1247 ISLAY06 IBE007 Cas9 TadA ins 1054 ISLAY07 IBE008 Cas9 TadA ins 1026 ISLAY08 IBE009 Cas9 TadA ins 768 ISLAY09 IBE020 delta HNH TadA 792 ISLAY20 IBE021 N-term fusion single TadA helix truncated 165-end ISLAY21 IBE029 TadA-Circular Permutant 116 ins 1067 ISLAY29 IBE031 TadA-Circular Permutant 136 ins 1248 ISLAY31 IBE032 TadA-Circular Permutant 136 ins 1052 ISLAY32 IBE035 delta 792-872 TadA ins ISLAY35 IBE036 delta 792-906 TadA ins ISLAY36 IBE043 TadA-Circular Permutant 65 ins 1246 ISLAY43 IBE044 TadA ins C-term truncate2 791 ISLAY44

[0451] A heterologous polypeptide (e.g., deaminase) can be inserted within a structural or functional domain of a Cas9 polypeptide. A heterologous polypeptide (e.g., deaminase) can be inserted between two structural or functional domains of a Cas9 polypeptide. A heterologous polypeptide (e.g., deaminase) can be inserted in place of a structural or functional domain of a Cas9 polypeptide, for example, after deleting the domain from the Cas9 polypeptide. The structural or functional domains of a Cas9 polypeptide can include, for example, RuvC I, RuvC II, RuvC III, Rec1, Rec2, PI, or HNH.

[0452] In some embodiments, the Cas9 polypeptide lacks one or more domains selected from the group consisting of: RuvC I, RuvC II, RuvC III, Rec1, Rec2, PI, or HNH domain. In some embodiments, the Cas9 polypeptide lacks a nuclease domain. In some embodiments, the Cas9 polypeptide lacks an HNH domain. In some embodiments, the Cas9 polypeptide lacks a portion of the HNH domain such that the Cas9 polypeptide has reduced or abolished HNH activity. In some embodiments, the Cas9 polypeptide comprises a deletion of the nuclease domain, and the deaminase is inserted to replace the nuclease domain. In some embodiments, the HNH domain is deleted and the deaminase is inserted in its place. In some embodiments, one or more of the RuvC domains is deleted and the deaminase is inserted in its place.

[0453] A fusion protein comprising a heterologous polypeptide can be flanked by a N-terminal and a C-terminal fragment of a napDNAbp. In some embodiments, the fusion protein comprises a deaminase flanked by a N-terminal fragment and a C-terminal fragment of a Cas9 polypeptide. The N terminal fragment or the C terminal fragment can bind the target polynucleotide sequence. The C-terminus of the N terminal fragment or the N-terminus of the C terminal fragment can comprise a part of a flexible loop of a Cas9 polypeptide. The C-terminus of the N terminal fragment or the N-terminus of the C terminal fragment can comprise a part of an alpha-helix structure of the Cas9 polypeptide. The N-terminal fragment or the C-terminal fragment can comprise a DNA binding domain. The N-terminal fragment or the C-terminal fragment can comprise a RuvC domain. The N-terminal fragment or the C-terminal fragment can comprise an HNH domain. In some embodiments, neither of the N-terminal fragment and the C-terminal fragment comprises an HNH domain.

[0454] In some embodiments, the C-terminus of the N terminal Cas9 fragment comprises an amino acid that is in proximity to a target nucleobase when the fusion protein deaminates the target nucleobase. In some embodiments, the N-terminus of the C terminal Cas9 fragment comprises an amino acid that is in proximity to a target nucleobase when the fusion protein deaminates the target nucleobase. The insertion location of different deaminases can be different in order to have proximity between the target nucleobase and an amino acid in the C-terminus of the N terminal Cas9 fragment or the N-terminus of the C terminal Cas9 fragment. For example, the insertion position of an ABE can be at an amino acid residue selected from the group consisting of: 1015, 1022, 1029, 1040, 1068, 1247, 1054, 1026, 768, 1067, 1248, 1052, and 1246 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0455] The N-terminal Cas9 fragment of a fusion protein (i.e. the N-terminal Cas9 fragment flanking the deaminase in a fusion protein) can comprise the N-terminus of a Cas9 polypeptide. The N-terminal Cas9 fragment of a fusion protein can comprise a length of at least about: 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, or 1300 amino acids. The N-terminal Cas9 fragment of a fusion protein can comprise a sequence corresponding to amino acid residues: 1-56, 1-95, 1-200, 1-300, 1-400, 1-500, 1-600, 1-700, 1-718, 1-765, 1-780, 1-906, 1-918, or 1-1100 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. The N-terminal Cas9 fragment can comprise a sequence comprising at least: 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% sequence identity to amino acid residues: 1-56, 1-95, 1-200, 1-300, 1-400, 1-500, 1-600, 1-700, 1-718, 1-765, 1-780, 1-906, 1-918, or 1-1100 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0456] The C-terminal Cas9 fragment of a fusion protein (i.e. the C-terminal Cas9 fragment flanking the deaminase in a fusion protein) can comprise the C-terminus of a Cas9 polypeptide. The C-terminal Cas9 fragment of a fusion protein can comprise a length of at least about: 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, or 1300 amino acids. The C-terminal Cas9 fragment of a fusion protein can comprise a sequence corresponding to amino acid residues: 1099-1368, 918-1368, 906-1368, 780-1368, 765-1368, 718-1368, 94-1368, or 56-1368 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide. The N-terminal Cas9 fragment can comprise a sequence comprising at least: 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% sequence identity to amino acid residues: 1099-1368, 918-1368, 906-1368, 780-1368, 765-1368, 718-1368, 94-1368, or 56-1368 as numbered in the above Cas9 reference sequence, or a corresponding amino acid residue in another Cas9 polypeptide.

[0457] The N-terminal Cas9 fragment and C-terminal Cas9 fragment of a fusion protein taken together may not correspond to a full-length naturally occurring Cas9 polypeptide sequence, for example, as set forth in the above Cas9 reference sequence.

[0458] The fusion protein described herein can effect targeted deamination with reduced deamination at non-target sites (e.g., off-target sites), such as reduced genome wide spurious deamination. The fusion protein described herein can effect targeted deamination with reduced bystander deamination at non-target sites. The undesired deamination or off-target deamination can be reduced by at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% compared with, for example, an end terminus fusion protein comprising the deaminase fused to a N terminus or a C terminus of a Cas9 polypeptide. The undesired deamination or off-target deamination can be reduced by at least one-fold, at least two-fold, at least three-fold, at least four-fold, at least five-fold, at least tenfold, at least fifteen fold, at least twenty fold, at least thirty fold, at least forty fold, at least fifty fold, at least 60 fold, at least 70 fold, at least 80 fold, at least 90 fold, or at least hundred fold, compared with, for example, an end terminus fusion protein comprising the deaminase fused to a N terminus or a C terminus of a Cas9 polypeptide.

[0459] In some embodiments, the deaminase (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) of the fusion protein deaminates no more than two nucleobases within the range of an R-loop. In some embodiments, the deaminase of the fusion protein deaminates no more than three nucleobases within the range of the R-loop. In some embodiments, the deaminase of the fusion protein deaminates no more than 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleobases within the range of the R-loop. An R-loop is a three-stranded nucleic acid structure including a DNA:RNA hybrid, a DNA:DNA or an RNA: RNA complementary structure and the associated with single-stranded DNA. As used herein, an R-loop may be formed when a target polynucleotide is contacted with a CRISPR complex or a base editing complex, wherein a portion of a guide polynucleotide, e.g. a guide RNA, hybridizes with and displaces with a portion of a target polynucleotide, e.g. a target DNA. In some embodiments, an R-loop comprises a hybridized region of a spacer sequence and a target DNA complementary sequence. An R-loop region may be of about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 nucleobase pairs in length. In some embodiments, the R-loop region is about 20 nucleobase pairs in length. It should be understood that, as used herein, an R-loop region is not limited to the target DNA strand that hybridizes with the guide polynucleotide. For example, editing of a target nucleobase within an R-loop region may be to a DNA strand that comprises the complementary strand to a guide RNA, or may be to a DNA strand that is the opposing strand of the strand complementary to the guide RNA. In some embodiments, editing in the region of the R-loop comprises editing a nucleobase on non-complementary strand (protospacer strand) to a guide RNA in a target DNA sequence.

[0460] The fusion protein described herein can effect target deamination in an editing window different from canonical base editing. In some embodiments, a target nucleobase is from about 1 to about 20 bases upstream of a PAM sequence in the target polynucleotide sequence. In some embodiments, a target nucleobase is from about 2 to about 12 bases upstream of a PAM sequence in the target polynucleotide sequence. In some embodiments, a target nucleobase is from about 1 to 9 base pairs, about 2 to 10 base pairs, about 3 to 11 base pairs, about 4 to 12 base pairs, about 5 to 13 base pairs, about 6 to 14 base pairs, about 7 to 15 base pairs, about 8 to 16 base pairs, about 9 to 17 base pairs, about 10 to 18 base pairs, about 11 to 19 base pairs, about 12 to 20 base pairs, about 1 to 7 base pairs, about 2 to 8 base pairs, about 3 to 9 base pairs, about 4 to 10 base pairs, about 5 to 11 base pairs, about 6 to 12 base pairs, about 7 to 13 base pairs, about 8 to 14 base pairs, about 9 to 15 base pairs, about 10 to 16 base pairs, about 11 to 17 base pairs, about 12 to 18 base pairs, about 13 to 19 base pairs, about 14 to 20 base pairs, about 1 to 5 base pairs, about 2 to 6 base pairs, about 3 to 7 base pairs, about 4 to 8 base pairs, about 5 to 9 base pairs, about 6 to 10 base pairs, about 7 to 11 base pairs, about 8 to 12 base pairs, about 9 to 13 base pairs, about 10 to 14 base pairs, about 11 to 15 base pairs, about 12 to 16 base pairs, about 13 to 17 base pairs, about 14 to 18 base pairs, about 15 to 19 base pairs, about 16 to 20 base pairs, about 1 to 3 base pairs, about 2 to 4 base pairs, about 3 to 5 base pairs, about 4 to 6 base pairs, about 5 to 7 base pairs, about 6 to 8 base pairs, about 7 to 9 base pairs, about 8 to 10 base pairs, about 9 to 11 base pairs, about 10 to 12 base pairs, about 11 to 13 base pairs, about 12 to 14 base pairs, about 13 to 15 base pairs, about 14 to 16 base pairs, about 15 to 17 base pairs, about 16 to 18 base pairs, about 17 to 19 base pairs, about 18 to 20 base pairs away or upstream of the PAM sequence. In some embodiments, a target nucleobase is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or more base pairs away from or upstream of the PAM sequence. In some embodiments, a target nucleobase is about 1, 2, 3, 4, 5, 6, 7, 8, or 9 base pairs upstream of the PAM sequence. In some embodiments, a target nucleobase is about 2, 3, 4, or 6 base pairs upstream of the PAM sequence.

[0461] The fusion protein can comprise more than one heterologous polypeptide. For example, the fusion protein can additionally comprise one or more UGI domains and/or one or more nuclear localization signals. The two or more heterologous domains can be inserted in tandem. The two or more heterologous domains can be inserted at locations such that they are not in tandem in the NapDNAbp.

[0462] A fusion protein can comprise a linker between the deaminase and the napDNAbp polypeptide. The linker can be a peptide or a non-peptide linker. For example, the linker can be an XTEN, (GGGS)n, (GGGGS)n, (G)n, (EAAAK)n, (GGS)n, SGSETPGTSESATPES. In some embodiments, the fusion protein comprises a linker between the N-terminal Cas9 fragment and the deaminase. In some embodiments, the fusion protein comprises a linker between the C-terminal Cas9 fragment and the deaminase. In some embodiments, the N-terminal and C-terminal fragments of napDNAbp are connected to the deaminase with a linker. In some embodiments, the N-terminal and C-terminal fragments are joined to the deaminase domain without a linker. In some embodiments, the fusion protein comprises a linker between the N-terminal Cas9 fragment and the deaminase, but does not comprise a linker between the C-terminal Cas9 fragment and the deaminase. In some embodiments, the fusion protein comprises a linker between the C-terminal Cas9 fragment and the deaminase, but does not comprise a linker between the N-terminal Cas9 fragment and the deaminase.

[0463] In some embodiments, the napDNAbp in the fusion protein is a Cas12 polypeptide, e.g., Cas12b/C2c1, or a fragment thereof. The Cas12 polypeptide can be a variant Cas12 polypeptide. In other embodiments, the N- or C-terminal fragments of the Cas12 polypeptide comprise a nucleic acid programmable DNA binding domain or a RuvC domain. In other embodiments, the fusion protein contains a linker between the Cas12 polypeptide and the catalytic domain. In other embodiments, the amino acid sequence of the linker is GGSGGS or GSSGSETPGTSESATPESSG. In other embodiments, the linker is a rigid linker. In other embodiments of the above aspects, the linker is encoded by GGAGGCTCTGGAGGAAGC or GGCTCITCTGGATCTGAAACACCIGGCACAAGCGAGAGCGCCACCCCTGAGAGCTCTGGC.

[0464] Fusion proteins comprising a heterologous catalytic domain flanked by N- and C-terminal fragments of a Cas12 polypeptide are also useful for base editing in the methods as described herein. Fusion proteins comprising Cas12 and one or more deaminase domains, e.g., adenosine deaminase, or comprising an adenosine deaminase domain flanked by Cas12 sequences are also useful for highly specific and efficient base editing of target sequences. In an embodiment, a chimeric Cas12 fusion protein contains a heterologous catalytic domain (e.g., adenosine deaminase, cytidine deaminase, or adenosine deaminase and cytidine deaminase) inserted within a Cas12 polypeptide. In some embodiments, the fusion protein comprises an adenosine deaminase domain and a cytidine deaminase domain inserted within a Cas12. In some embodiments, an adenosine deaminase is fused within Cas12 and a cytidine deaminase is fused to the C-terminus. In some embodiments, an adenosine deaminase is fused within Cas12 and a cytidine deaminase fused to the N-terminus. In some embodiments, a cytidine deaminase is fused within Cas12 and an adenosine deaminase is fused to the C-terminus. In some embodiments, a cytidine deaminase is fused within Cas12 and an adenosine deaminase fused to the N-terminus. Exemplary structures of a fusion protein with an adenosine deaminase and a cytidine deaminase and a Cas12 are provided as follows:

[0465] NH.sub.2-[Cas12(adenosine deaminase)]-[cytidine deaminase]-COOH;

[0466] NH.sub.2-[cytidine deaminase]-[Cas12(adenosine deaminase)]-COOH;

[0467] NH.sub.2-[Cas12(cytidine deaminase)]-[adenosine deaminase]-COOH; or

[0468] NH.sub.2-[adenosine deaminase]-[Cas12(cytidine deaminase)]-COOH;

In some embodiments, the “-” used in the general architecture above indicates the presence of an optional linker.

[0469] In various embodiments, the catalytic domain has DNA modifying activity (e.g., deaminase activity), such as adenosine deaminase activity. In some embodiments, the adenosine deaminase is a TadA (e.g., TadA7.10). In some embodiments, the TadA is a TadA*8. In some embodiments, a TadA*8 is fused within Cas12 and a cytidine deaminase is fused to the C-terminus. In some embodiments, a TadA*8 is fused within Cas12 and a cytidine deaminase fused to the N-terminus. In some embodiments, a cytidine deaminase is fused within Cas12 and a TadA*8 is fused to the C-terminus. In some embodiments, a cytidine deaminase is fused within Cas12 and a TadA*8 fused to the N-terminus. Exemplary structures of a fusion protein with a TadA*8 and a cytidine deaminase and a Cas12 are provided as follows:

[0470] N-[Cas12(TadA*8)]-[cytidine deaminase]-C;

[0471] N-[cytidine deaminase]-[Cas12(TadA*8)]-C;

[0472] N-[Cas12(cytidine deaminase)]-[TadA*8]-C; or

[0473] N-[TadA*8]-[Cas12(cytidine deaminase)]-C.

In some embodiments, the “-” used in the general architecture above indicates the presence of an optional linker.

[0474] In other embodiments, the fusion protein contains one or more catalytic domains. In other embodiments, at least one of the one or more catalytic domains is inserted within the Cas12 polypeptide or is fused at the Cas12 N-terminus or C-terminus. In other embodiments, at least one of the one or more catalytic domains is inserted within a loop, an alpha helix region, an unstructured portion, or a solvent accessible portion of the Cas12 polypeptide. In other embodiments, the Cas12 polypeptide is Cas12a, Cas12b, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i. In other embodiments, the Cas12 polypeptide has at least about 85% amino acid sequence identity to Bacillus hisashii Cas12b, Bacillus thermoamylovorans Cas12b, Bacillus sp. V3-13 Cas12b, or Alicyclobacillus acidiphilus Cas12b. In other embodiments, the Cas12 polypeptide has at least about 90% amino acid sequence identity to Bacillus hisashii Cas12b, Bacillus thermoamylovorans Cas12b, Bacillus sp. V3-13 Cas12b, or Alicyclobacillus acidiphilus Cas12b. In other embodiments, the Cas12 polypeptide has at least about 95% amino acid sequence identity to Bacillus hisashii Cas12b, Bacillus thermoamylovorans Cas12b, Bacillus sp. V3-13 Cas12b, or Alicyclobacillus acidiphilus Cas12b. In other embodiments, the Cas12 polypeptide contains or consists essentially of a fragment of Bacillus hisashii Cas12b, Bacillus thermoamylovorans Cas12b, Bacillus sp. V3-13 Cas12b, or Alicyclobacillus acidiphilus Cas12b.

[0475] In other embodiments, the catalytic domain is inserted between amino acid positions 153-154, 255-256, 306-307, 980-981, 1019-1020, 534-535, 604-605, or 344-345 of BhCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i. In other embodiments, the catalytic domain is inserted between amino acids P153 and S154 of BhCas12b. In other embodiments, the catalytic domain is inserted between amino acids K255 and E256 of BhCas12b. In other embodiments, the catalytic domain is inserted between amino acids D980 and G981 of BhCas12b. In other embodiments, the catalytic domain is inserted between amino acids K1019 and L1020 of BhCas12b. In other embodiments, the catalytic domain is inserted between amino acids F534 and P535 of BhCas12b. In other embodiments, the catalytic domain is inserted between amino acids K604 and G605 of BhCas12b. In other embodiments, the catalytic domain is inserted between amino acids H344 and F345 of BhCas12b. In other embodiments, catalytic domain is inserted between amino acid positions 147 and 148, 248 and 249, 299 and 300, 991 and 992, or 1031 and 1032 of BvCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i. In other embodiments, the catalytic domain is inserted between amino acids P147 and D148 of BvCas12b. In other embodiments, the catalytic domain is inserted between amino acids G248 and G249 of BvCas12b. In other embodiments, the catalytic domain is inserted between amino acids P299 and E300 of BvCas12b. In other embodiments, the catalytic domain is inserted between amino acids G991 and E992 of BvCas12b. In other embodiments, the catalytic domain is inserted between amino acids K1031 and M1032 of BvCas12b. In other embodiments, the catalytic domain is inserted between amino acid positions 157 and 158, 258 and 259, 310 and 311, 1008 and 1009, or 1044 and 1045 of AaCas12b or a corresponding amino acid residue of Cas12a, Cas12c, Cas12d, Cas12e, Cas12g, Cas12h, or Cas12i. In other embodiments, the catalytic domain is inserted between amino acids P157 and G158 of AaCas12b. In other embodiments, the catalytic domain is inserted between amino acids V258 and G259 of AaCas12b. In other embodiments, the catalytic domain is inserted between amino acids D310 and P311 of AaCas12b. In other embodiments, the catalytic domain is inserted between amino acids G1008 and E1009 of AaCas12b. In other embodiments, the catalytic domain is inserted between amino acids G1044 and K1045 at of AaCas12b.

[0476] In other embodiments, the fusion protein contains a nuclear localization signal (e.g., a bipartite nuclear localization signal). In other embodiments, the amino acid sequence of the nuclear localization signal is MAPKKKRKVGIHGVPAA. In other embodiments of the above aspects, the nuclear localization signal is encoded by the following sequence: ATGGCCCCAAAGAAGAAGCGGAAGGTCGGTATCCACGGAGTCCCAGCAGCC. In other embodiments, the Cas12b polypeptide contains a mutation that silences the catalytic activity of a RuvC domain. In other embodiments, the Cas12b polypeptide contains D574A, D829A and/or D952A mutations. In other embodiments, the fusion protein further contains a tag (e.g., an influenza hemagglutinin tag).

[0477] In some embodiments, the fusion protein comprises a napDNAbp domain (e.g., Cas12-derived domain) with an internally fused nucleobase editing domain (e.g., all or a portion of a deaminase domain, e.g., an adenosine deaminase domain). In some embodiments, the napDNAbp is a Cas12b. In some embodiments, the base editor comprises a BhCas12b domain with an internally fused TadA*8 domain inserted at the loci provided in Table B below.

TABLE-US-00061 TABLE B Insertion loci in Cas12b proteins BhCas12b Insertion site Inserted between aa position 1 153 PS position 2 255 KE position 3 306 DE position 4 980 DG position 5 1019 KL position 6 534 FP position 7 604 KG position 8 344 HF BvCas12b Insertion site Inserted between aa position 1 147 PD position 2 248 GG position 3 299 PE position 4 991 GE position 5 1031 KM AaCas12b Insertion site Inserted between aa position 1 157 PG position 2 258 VG position 3 310 DP position 4 1008 GE position 5 1044 GK

[0478] By way of nonlimiting example, an adenosine deaminase (e.g., ABE8.13) may be inserted into a BhCas12b to produce a fusion protein (e.g., ABE8.13-BhCas12b) that effectively edits a nucleic acid sequence. In some embodiments, the base editing system described herein comprises an ABE with TadA inserted into a Cas9.

Cas9 Domains with Reduced PAM Exclusivity

[0479] Typically, Cas9 proteins, such as Cas9 from S. pyogenes (spCas9), require a canonical NGG PAM sequence to bind a particular nucleic acid region, where the “N” in “NGG” is adenosine (A), thymidine (T), or cytosine (C), and the G is guanosine. This may limit the ability to edit desired bases within a genome. In some embodiments, the base editing fusion proteins provided herein may need to be placed at a precise location, for example a region comprising a target base that is upstream of the PAM. See e.g., Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016), the entire contents of which are hereby incorporated by reference. Accordingly, in some embodiments, any of the fusion proteins provided herein may contain a Cas9 domain that is capable of binding a nucleotide sequence that does not contain a canonical (e.g., NGG) PAM sequence. Cas9 domains that bind to non-canonical PAM sequences have been described in the art and would be apparent to the skilled artisan. For example, Cas9 domains that bind non-canonical PAM sequences have been described in Kleinstiver, B. P., et al., “Engineered CRISPR-Cas9 nucleases with altered PAM specificities” Nature 523, 481-485 (2015); and Kleinstiver, B. P., et al., “Broadening the targeting range of Staphylococcus aureus CRISPR-Cas9 by modifying PAM recognition” Nature Biotechnology 33, 1293-1298 (2015); Nishimasu, H., et al., “Engineered CRISPR-Cas9 nuclease with expanded targeting space” Science. 2018 Sep. 21; 361(6408):1259-1262, Chatterjee, P., et al., Minimal PAM specificity of a highly similar SpCas9 ortholog” Sci Adv. 2018 Oct. 24; 4 (10):eaau0766. doi: 10.1126/sciadv.aau0766, the entire contents of each are hereby incorporated by reference.

Nucleobase Editing Domain

[0480] Described herein are base editors comprising a fusion protein that includes a polynucleotide programmable nucleotide binding domain and a nucleobase editing domain (e.g., a deaminase domain). The base editor can be programmed to edit one or more bases in a target polynucleotide sequence by interacting with a guide polynucleotide capable of recognizing the target sequence. Once the target sequence has been recognized, the base editor is anchored on the polynucleotide where editing is to occur and the deaminase domain components of the base editor can then edit a target base.

[0481] In some embodiments, the nucleobase editing domain includes a deaminase domain. As particularly described herein, the deaminase domain includes a cytosine deaminase or an adenosine deaminase. In embodiments, base editors include cytidine base editors (e.g., BE4) that convert target C⋅G base pairs to TA and adenine base editors (e.g., ABE7.10 and others) that convert A⋅T to G⋅C. In some embodiments, the terms “cytosine deaminase” and “cytidine deaminase” can be used interchangeably. In some embodiments, the terms “adenine deaminase” and “adenosine deaminase” can be used interchangeably. Details of nucleobase editing proteins are described in International PCT Application Nos. PCT/2017/045381 (WO2018/027078) and PCT/US2016/058344 (WO2017/070632), each of which is incorporated herein by reference for its entirety. Also see Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N. M., et al., “Programmable base editing of A⋅T to G⋅C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); and Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017), the entire contents of which are hereby incorporated by reference.

A to G Editing

[0482] In some embodiments, a base editor described herein can comprise a deaminase domain which includes an adenosine deaminase. Such an adenosine deaminase domain of a base editor can facilitate the editing of an adenine (A) nucleobase to a guanine (G) nucleobase by deaminating the A to form inosine (I), which exhibits base pairing properties of G. Adenosine deaminase is capable of deaminating (i.e., removing an amine group) adenine of a deoxyadenosine residue in deoxyribonucleic acid (DNA).

[0483] In some embodiments, the nucleobase editors provided herein can be made by fusing together one or more protein domains, thereby generating a fusion protein. In certain embodiments, the fusion proteins provided herein comprise one or more features that improve the base editing activity (e.g., efficiency, selectivity, and specificity) of the fusion proteins. For example, the fusion proteins provided herein can comprise a Cas9 domain that has reduced nuclease activity. In some embodiments, the fusion proteins provided herein can have a Cas9 domain that does not have nuclease activity (dCas9), or a Cas9 domain that cuts one strand of a duplexed DNA molecule, referred to as a Cas9 nickase (nCas9). Without wishing to be bound by any particular theory, the presence of the catalytic residue (e.g., H840) maintains the activity of the Cas9 to cleave the non-edited (e.g., non-deaminated) strand containing a T opposite the targeted A. Mutation of the catalytic residue (e.g., D10 to A10) of Cas9 prevents cleavage of the edited strand containing the targeted A residue. Such Cas9 variants are able to generate a single-strand DNA break (nick) at a specific location based on the gRNA-defined target sequence, leading to repair of the non-edited strand, ultimately resulting in a T to C change on the non-edited strand. In some embodiments, an A-to-G base editor further comprises an inhibitor of inosine base excision repair, for example, a uracil glycosylase inhibitor (UGI) domain or a catalytically inactive inosine specific nuclease. Without wishing to be bound by any particular theory, the UGI domain or catalytically inactive inosine specific nuclease can inhibit or prevent base excision repair of a deaminated adenosine residue (e.g., inosine), which can improve the activity or efficiency of the base editor.

[0484] A base editor comprising an adenosine deaminase can act on any polynucleotide, including DNA, RNA and DNA-RNA hybrids. In certain embodiments, a base editor comprising an adenosine deaminase can deaminate a target A of a polynucleotide comprising RNA. For example, the base editor can comprise an adenosine deaminase domain capable of deaminating a target A of an RNA polynucleotide and/or a DNA-RNA hybrid polynucleotide. In an embodiment, an adenosine deaminase incorporated into a base editor comprises all or a portion of adenosine deaminase acting on RNA (ADAR, e.g., ADAR1 or ADAR2). In another embodiment, an adenosine deaminase incorporated into a base editor comprises all or a portion of adenosine deaminase acting on tRNA (ADAT). A base editor comprising an adenosine deaminase domain can also be capable of deaminating an A nucleobase of a DNA polynucleotide. In an embodiment an adenosine deaminase domain of a base editor comprises all or a portion of an ADAT comprising one or more mutations which permit the ADAT to deaminate a target A in DNA. For example, the base editor can comprise all or a portion of an ADAT from Escherichia coli (EcTadA) comprising one or more of the following mutations: D108N, A106V, D147Y, E155V, L84F, H123Y, I157F, or a corresponding mutation in another adenosine deaminase.

[0485] The adenosine deaminase can be derived from any suitable organism (e.g., E. coli). In some embodiments, the adenine deaminase is a naturally-occurring adenosine deaminase that includes one or more mutations corresponding to any of the mutations provided herein (e.g., mutations in ecTadA). The corresponding residue in any homologous protein can be identified by e.g., sequence alignment and determination of homologous residues. The mutations in any naturally-occurring adenosine deaminase (e.g., having homology to ecTadA) that corresponds to any of the mutations described herein (e.g., any of the mutations identified in ecTadA) can be generated accordingly.

TadA

[0486] In particular embodiments, the TadA is any one of the TadA described in PCT/US2017/045381 (WO 2018/027078), which is incorporated herein by reference in its entirety.

[0487] In particular embodiments, the fusion proteins comprise a single (e.g., provided as a monomer) TadA*8 variant. In some embodiments, the TadA*8 is linked to a Cas9 nickase. In some embodiments, the fusion proteins of the invention comprise as a heterodimer a wild-type TadA (TadA (wt)) linked to a TadA*8 variant. In other embodiments, the fusion proteins of the invention comprise as a heterodimer a TadA*7.10 linked to a TadA*8 variant. In some embodiments, the base editor is ABE8 comprising a TadA*8 variant monomer. In some embodiments, the base editor is ABE8 comprising a heterodimer of a TadA*8 variant and a TadA (wt). In some embodiments, the base editor is ABE8 comprising a heterodimer of a TadA*8 variant and TadA*7.10. In some embodiments, the base editor is ABE8 comprising a heterodimer of a TadA*8 variants. In some embodiments, the TadA*8 variant is selected from Table 7. In some embodiments, the ABE8 is selected from Table 7. The relevant sequences follow:

TABLE-US-00062 Wild-type TadA (TadA(wt)) or “the TadA reference sequence” MSEVEFSHEYWMRHALTLAKRAWDEREVPVGAVLVH NNRVIGEGWNRPIGRHDPTAHAEIMALRQGGLVMQN YRLIDATLYVTLEPCVMCAGAMIHSRIGRVVFGARD AKTGAAGSLMDVLHHPGMNHRVEITEGILADECAAL LSDFFRMRRQEIKAQKKAQSSTD TadA*7.10: MSEVEFSHEYW MRHALTLAKR ARDEREVPVG AVLVLNNRVI GEGWNRAIGL HDPTAHAEIM ALRQGGLVMQ NYRLIDATLY VTFEPCVMCA GAMIHSRIGR VVFGVRNAKT GAAGSLMDVL HYPGMNHRVE ITEGILADEC AALLCYFFRM PRQVFNAQKK AQSSTD

[0488] In some embodiments, the adenosine deaminase comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the amino acid sequences set forth in any of the adenosine deaminases provided herein. It should be appreciated that adenosine deaminases provided herein may include one or more mutations (e.g., any of the mutations provided herein). The disclosure provides any deaminase domains with a certain percent identity plus any of the mutations or combinations thereof described herein. In some embodiments, the adenosine deaminase comprises an amino acid sequence that has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, or more mutations compared to a reference sequence, or any of the adenosine deaminases provided herein. In some embodiments, the adenosine deaminase comprises an amino acid sequence that has at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 110, at least 120, at least 130, at least 140, at least 150, at least 160, or at least 170 identical contiguous amino acid residues as compared to any one of the amino acid sequences known in the art or described herein.

[0489] In some embodiments the TadA deaminase is a full-length E. coli TadA deaminase. For example, in certain embodiments, the adenosine deaminase comprises the amino acid sequence:

TABLE-US-00063 MRRAFITGVFFLSEVEFSHEYWMRHALTLAK RAWDEREVPVGAVLVHNNRVIGEGWNRPIGR HDPTAHAEIMALRQGGLVMQNYRLIDATLYV TLEPCVMCAGAMIHSRIGRVVFGARDAKTGA AGSLMDVLHHPGMNHRVEITEGILADECAAL LSDFFRMRRQEI KAQKKAQSSTD.

[0490] It should be appreciated, however, that additional adenosine deaminases useful in the present application would be apparent to the skilled artisan and are within the scope of this disclosure. For example, the adenosine deaminase may be a homolog of adenosine deaminase acting on tRNA (ADAT). Without limitation, the amino acid sequences of exemplary AD AT homologs include the following:

TABLE-US-00064 Staphylococcus aureus TadA: MGSHMTNDIYFMTLAIEEAKKAAQLGEVPIGAIIT KDDEVIARAHNLRETLQQPTAHAEHIAIERAAKVL GSWRLEGCTLYVTLEPCVMCAGTIVMSRIPRVVYG ADDPKGGCSGSLMNLLQQSNFNHRAIVDKGVLKEA CSTLLTTFFKNLRANKKSTN Bacillus subtilis TadA: MTQDELYMKEAIKEAKKAEEKGEVPIGAVLVINGE IIARAHNLRETEQRSIAHAEMLVIDEACKALGTWR LEGATLYVTLEPCPMCAGAVVLSRVEKVVFGAFDP KGGCSGTLMNLLQEERFNHQAEVVSGVLEEECGGM LSAFFRELRKKKKAARKNLSE Salmonella typhimurium (S. typhimurium) TadA: MPPAFITGVTSLSDVELDHEYWMRHALTLAKRAWD EREVPVGAVLVHNHRVIGEGWNRPIGRHDPTAHAE IMALRQGGLVLQNYRLLDTTLYVTLEPCVMCAGAM VHSRIGRVVFGARDAKTGAAGSLIDVLHHPGMNHR VEIIEGVLRDECATLLSDFFRMRRQEIKALKKADR AEGAGPAV Shewanella putrefaciens (S. putrefaciens) TadA: MDEYWMQVAMQMAEKAEAAGEVPVGAVLVKDGQQI ATGYNLSISQHDPTAHAEILCLRSAGKKLENYRLL DATLYITLEPCAMCAGAMVHSRIARVVYGARDEKT GAAGTVVNLLQHPAFNHQVEVTSGVLAEACSAQLS RFFKRRRDEKKALKLAQRAQQGIE Haemophilus influenzaeF3031 (H. influenzae) TadA: MDAAKVRSEFDEKMMRYALELADKAEALGEIPVGA VLVDDARNIIGEGWNLSIVQSDPTAHAElIALRNG AKNIQNYRLLNSTLYVTLEPCTMCAGAILHSRIKR LVFGASDYKTGAIGSRFHFFDDYKNINHTLEITSG VLAEECSQKLSTFFQKRREEKKIEKALLKSLSDK Caulobacter crescentus (C. crescentus) TadA: MRTDESEDQDHRMMRLALDAARAAAEAGETPVGAV ILDPSTGEVIATAGNGPIAAHDPTAHAEIAAMRAA AAKLGNYRLTDLTLVVTLEPCAMCAGAISHARIGR VVFGADDPKGGAVVHGPKFFAQPTCHWRPEVTGGV LADESADLLRGFFRARRKAKI Geobacter sulfurreducens (G. sulfitrreducens) TadA: MSSLKKTPIRDDAYWMGKAIREAAKAAARDEVPIG AVIVRDGAVIGRGHNLREGSNDPSAHAEMIAIRQA ARRSANWRLTGATLYVTLEPCLMCMGAIILARLER VVFGCYDPKGGAAGSLYDLSADPRLNHQVRLSPGV CQEECGTMLSDFFRDLRRRKKAKATPALFIDERKV PPEP An embodiment of E. coli  TadA (ecTadA) includes the following: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLV LNNRVIGEGWNRAIGLHDPTAHAEIMALRQGGLVM QNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFG VRNAKTGAAGSLMDVLHYPGMNHRVEITEGILADE CAALLCYFFRMPRQVFNAQKKAQSSTD

[0491] In some embodiments, the adenosine deaminase is from a prokaryote. In some embodiments, the adenosine deaminase is from a bacterium. In some embodiments, the adenosine deaminase is from Escherichia coli, Staphylococcus aureus, Salmonella typhi, Shewanella putrefaciens, Haemophilus influenzae, Caulobacter crescentus, or Bacillus subtilis. In some embodiments, the adenosine deaminase is from E. coli.

[0492] In one embodiment, a fusion protein of the invention comprises a wild-type TadA linked to TadA7.10, which is linked to Cas9 nickase. In particular embodiments, the fusion proteins comprise a single TadA7.10 domain (e.g., provided as a monomer). In other embodiments, the ABE7.10 editor comprises TadA7.10 and TadA (wt), which are capable of forming heterodimers.

[0493] In some embodiments, the adenosine deaminase comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the amino acid sequences set forth in any of the adenosine deaminases provided herein. It should be appreciated that adenosine deaminases provided herein may include one or more mutations (e.g., any of the mutations provided herein). The disclosure provides any deaminase domains with a certain percent identity plus any of the mutations or combinations thereof described herein. In some embodiments, the adenosine deaminase comprises an amino acid sequence that has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, or more mutations compared to a reference sequence, or any of the adenosine deaminases provided herein. In some embodiments, the adenosine deaminase comprises an amino acid sequence that has at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 110, at least 120, at least 130, at least 140, at least 150, at least 160, or at least 170 identical contiguous amino acid residues as compared to any one of the amino acid sequences known in the art or described herein.

[0494] It should be appreciated that any of the mutations provided herein (e.g., based on the TadA reference sequence) can be introduced into other adenosine deaminases, such as E. coli TadA (ecTadA), S. aureus TadA (saTadA), or other adenosine deaminases (e.g., bacterial adenosine deaminases). It would be apparent to the skilled artisan that additional deaminases may similarly be aligned to identify homologous amino acid residues that can be mutated as provided herein. Thus, any of the mutations identified in the TadA reference sequence can be made in other adenosine deaminases (e.g., ecTada) that have homologous amino acid residues. It should also be appreciated that any of the mutations provided herein can be made individually or in any combination in the TadA reference sequence or another adenosine deaminase.

[0495] In some embodiments, the adenosine deaminase comprises a D108X mutation in the TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises a D108G, D108N, D108V, D108A, or D108Y mutation, or a corresponding mutation in another adenosine deaminase.

[0496] In some embodiments, the adenosine deaminase comprises an A106X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an A106V mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., wild type TadA or ecTadA).

[0497] In some embodiments, the adenosine deaminase comprises a E155X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where the presence of X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises a E155D, E155G, or E155V mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0498] In some embodiments, the adenosine deaminase comprises a D147X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where the presence of X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises a D147Y, mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0499] In some embodiments, the adenosine deaminase comprises an A106X, E155X, or D147X, mutation in the TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an E155D, E155G, or E155V mutation. In some embodiments, the adenosine deaminase comprises a D147Y.

[0500] For example, an adenosine deaminase can contain a D108N, a A106V, a E155V, and/or a D147Y mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA). In some embodiments, an adenosine deaminase comprises the following group of mutations (groups of mutations are separated by a “;”) in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA): D108N and A106V; D108N and E155V; D108N and D147Y; A106V and E155V; A106V and D147Y; E155V and D147Y; D108N, A106V, and E55V; D108N, A106V, and D147Y; D108N, E55V, and D147Y; A106V, E55V, and D147Y; and D108N, A106V, E155V, and D147Y. It should be appreciated, however, that any combination of corresponding mutations provided herein can be made in an adenosine deaminase (e.g., ecTadA).

[0501] In some embodiments, the adenosine deaminase comprises one or more of a H8X, T17X, L18X, W23X, L34X, W45X, R51X, A56X, E59X, E85X, M94X, I95X, V102X, F104X, A106X, R107X, D108X, K110X, M118X, N127X, A138X, F149X, M151X, R153X, Q154X, I156X, and/or K157X mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA), where the presence of X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one or more of H8Y, T17S, L18E, W23L, L34S, W45L, R51H, A56E, or A56S, E59G, E85K, or E85G, M94L, 1951, V102A, F104L, A106V, R107C, or R107H, or R107P, D108G, or D108N, or D108V, or D108A, or D108Y, K110I, M118K, N127S, A138V, F149Y, M151V, R153C, Q154L, I156D, and/or K157R mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA).

[0502] In some embodiments, the adenosine deaminase comprises one or more of a H8X, D108X, and/or N127X mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid. In some embodiments, the adenosine deaminase comprises one or more of a H8Y, D108N, and/or N127S mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA).

[0503] In some embodiments, the adenosine deaminase comprises one or more of H8X, R26X, M61X, L68X, M70X, A106X, D108X, A109X, N127X, D147X, R152X, Q154X, E155X, K161X, Q163X, and/or T166X mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one or more of H8Y, R26W, M61I, L68Q, M70V, A106T, D108N, A109T, N127S, D147Y, R152C, Q154H or Q154R, E155G or E155V or E155D, K161Q, Q163H, and/or T166P mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA).

[0504] In some embodiments, the adenosine deaminase comprises one, two, three, four, five, or six mutations selected from the group consisting of H8X, D108X, N127X, D147X, R152X, and Q154X in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one, two, three, four, five, six, seven, or eight mutations selected from the group consisting of H8X, M61X, M70X, D108X, N127X, Q154X, E155X, and Q163X in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one, two, three, four, or five, mutations selected from the group consisting of H8X, D108X, N127X, E155X, and T166X in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase.

[0505] In some embodiments, the adenosine deaminase comprises one, two, three, four, five, or six mutations selected from the group consisting of H8X, A106X, D108X, mutation or mutations in another adenosine deaminase, where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one, two, three, four, five, six, seven, or eight mutations selected from the group consisting of H8X, R126X, L68X, D108X, N127X, D147X, and E155X, or a corresponding mutation or mutations in another adenosine deaminase, where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one, two, three, four, or five, mutations selected from the group consisting of H8X, D108X, A109X, N127X, and E155X in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase.

[0506] In some embodiments, the adenosine deaminase comprises one, two, three, four, five, or six mutations selected from the group consisting of H8Y, D108N, N127S, D147Y, R152C, and Q154H in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises one, two, three, four, five, six, seven, or eight mutations selected from the group consisting of H8Y, M61I, M70V, D108N, N127S, Q154R, E155G and Q163H in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises one, two, three, four, or five, mutations selected from the group consisting of H8Y, D108N, N127S, E155V, and T166P in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises one, two, three, four, five, or six mutations selected from the group consisting of H8Y, A106T, D108N, N127S, E155D, and K161Q in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises one, two, three, four, five, six, seven, or eight mutations selected from the group consisting of H8Y, R126W, L68Q, D108N, N127S, D147Y, and E155V in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises one, two, three, four, or five, mutations selected from the group consisting of H8Y, D108N, A109T, N127S, and E155G in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA).

[0507] Any of the mutations provided herein and any additional mutations (e.g., based on the ecTadA amino acid sequence) can be introduced into any other adenosine deaminases. Any of the mutations provided herein can be made individually or in any combination in TadA reference sequence or another adenosine deaminase (e.g., ecTadA).

[0508] Details of A to G nucleobase editing proteins are described in International PCT Application No. PCT/2017/045381 (WO2018/027078) and Gaudelli, N. M., et al., “Programmable base editing of A⋅T to G⋅C in genomic DNA without DNA cleavage” Nature, 551, 464-471 (2017), the entire contents of which are hereby incorporated by reference.

[0509] In some embodiments, the adenosine deaminase comprises one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises a D108N, D108G, or D108V mutation in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises a A106V and D108N mutation in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises R107C and D108N mutations in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises a H8Y, D108N, N127S, D147Y, and Q154H mutation in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises a H8Y, R24W, D108N, N127S, D147Y, and E155V mutation in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises a D108N, D147Y, and E155V mutation in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises a H8Y, D108N, and N127S mutation in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises a A106V, D108N, D147Y and E155V mutation in TadA reference sequence, or corresponding mutations in another adenosine deaminase (e.g., ecTadA).

[0510] In some embodiments, the adenosine deaminase comprises one or more of a S2X, H8X, I49X, L84X, H123X, N127X, I156X and/or K160X mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase, where the presence of X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one or more of S2A, H8Y, I49F, L84F, H123Y, N127S, I156F and/or K160S mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA).

[0511] In some embodiments, the adenosine deaminase comprises an L84X mutation adenosine deaminase, where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an L84F mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0512] In some embodiments, the adenosine deaminase comprises an H123X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an H123Y mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0513] In some embodiments, the adenosine deaminase comprises an I157X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an 1157F mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0514] In some embodiments, the adenosine deaminase comprises one, two, three, four, five, six, or seven mutations selected from the group consisting of L84X, A106X, D108X, H123X, D147X, E155X, and I156X in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one, two, three, four, five, or six mutations selected from the group consisting of S2X, I49X, A106X, D108X, D147X, and E155X in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one, two, three, four, or five, mutations selected from the group consisting of H8X, A106X, D108X, N127X, and K160X in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA), where X indicates the presence of any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase.

[0515] In some embodiments, the adenosine deaminase comprises one, two, three, four, five, six, or seven mutations selected from the group consisting of L84F, A106V, D108N, H123Y, D147Y, E155V, and I156F in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises one, two, three, four, five, or six mutations selected from the group consisting of S2A, I49F, A106V, D108N, D147Y, and E155V in TadA reference sequence.

[0516] In some embodiments, the adenosine deaminase comprises one, two, three, four, or five, mutations selected from the group consisting of H8Y, A106T, D108N, N127S, and K160S in TadA reference sequence, or a corresponding mutation or mutations in another adenosine deaminase (e.g., ecTadA).

[0517] In some embodiments, the adenosine deaminase comprises one or more of a E25X, R26X, R107X, A142X, and/or A143X mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA), where the presence of X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one or more of E25M, E25D, E25A, E25R, E25V, E25S, E25Y, R26G, R26N, R26Q, R26C, R26L, R26K, R107P, R07K, R107A, R107N, R107W, R107H, R107S, A142N, A142D, A142G, A143D, A143G, A143E, A143L, A143W, A143M, A143S, A143Q and/or A143R mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA). In some embodiments, the adenosine deaminase comprises one or more of the mutations described herein corresponding to TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA).

[0518] In some embodiments, the adenosine deaminase comprises an E25X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an E25M, E25D, E25A, E25R, E25V, E25S, or E25Y mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0519] In some embodiments, the adenosine deaminase comprises an R26X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises R26G, R26N, R26Q, R26C, R26L, or R26K mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0520] In some embodiments, the adenosine deaminase comprises an R107X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an R107P, R07K, R107A, R107N, R107W, R107H, or R107S mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0521] In some embodiments, the adenosine deaminase comprises an A142X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an A142N, A142D, A142G, mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0522] In some embodiments, the adenosine deaminase comprises an A143X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an A143D, A143G, A143E, A143L, A143W, A143M, A143S, A143Q and/or A143R mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0523] In some embodiments, the adenosine deaminase comprises one or more of a H36X, N37X, P48X, I49X, R51X, M70X, N72X, D77X, E134X, S 146X, Q154X, K157X, and/or K161X mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA), where the presence of X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises one or more of H36L, N37T, N37S, P48T, P48L, I49V, R51H, R51L, M70L, N72S, D77G, E134G, S146R, S146C, Q154H, K157N, and/or K161T mutation in TadA reference sequence, or one or more corresponding mutations in another adenosine deaminase (e.g., ecTadA).

[0524] In some embodiments, the adenosine deaminase comprises an H36X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an H36L mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0525] In some embodiments, the adenosine deaminase comprises an N37X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an N37T, or N37S mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0526] In some embodiments, the adenosine deaminase comprises an P48X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an P48T, or P48L mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0527] In some embodiments, the adenosine deaminase comprises an R51X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase, where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an R51H, or R51L mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0528] In some embodiments, the adenosine deaminase comprises an S146X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises an S146R, or S146C mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0529] In some embodiments, the adenosine deaminase comprises an K157X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises a K157N mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0530] In some embodiments, the adenosine deaminase comprises an P48X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises a P48S, P48T, or P48A mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0531] In some embodiments, the adenosine deaminase comprises an A142X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises a A142N mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0532] In some embodiments, the adenosine deaminase comprises an W23X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises a W23R, or W23L mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0533] In some embodiments, the adenosine deaminase comprises an R152X mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA), where X indicates any amino acid other than the corresponding amino acid in the wild-type adenosine deaminase. In some embodiments, the adenosine deaminase comprises a R152P, or R52H mutation in TadA reference sequence, or a corresponding mutation in another adenosine deaminase (e.g., ecTadA).

[0534] In one embodiment, the adenosine deaminase may comprise the mutations H36L, R51L, L84F, A106V, D108N, H123Y, S146C, D147Y, E155V, I156F, and K157N. In some embodiments, the adenosine deaminase comprises the following combination of mutations relative to TadA reference sequence, where each mutation of a combination is separated by a “_” and each combination of mutations is between parentheses:

(A106V_D108N),

(R107C_D108N),

(H8Y_D108N_N127S_D147Y_Q154H),

(H8Y_R24W_D108N_N127S_D147Y_E155V),

(D108N_D147Y_E155V),

(H8Y_D108N_N127S),

(H8Y_D108N_N127S_D147Y_Q154H),

(A106V_D108N_D147Y_E155V),

(D108Q_D147Y_E155V),

(D108M_D147Y_E155V),

(D108L_D147Y_E155V),

(D108K_D147Y_E155V),

(D108I_D147Y_E155V),

(D108F_D147Y_E155V),

(A106V_D108N_D147Y),

(A106V_D108M_D147Y_E155V),

(E59A_A106V_D108N_D147Y_E155V),

[0535] (E59A cat dead_A106V_D108N_D147Y_E155V),

(L84F_A106V_D108N_H123Y_D147Y_E155V_I156Y),

(L84F_A106V_D108N_H123Y_D147Y_E155V_I156F),

(D103A_D104N),

(G22P_D103A_D104N),

(G22P_D103A_D104N_S138 A),

(D103A_D104N_S138A),

(R26G_L84F_A106V_R107H_D108N_H123Y_A142N_A143D_D147Y_E155V_I156F),

(E25G R26G_L84F_A106V_R107H_D108N_H123Y_A142N_A143D_D147Y_E155V_I156F),

(E25D_R26G_L84F_A106V_R107K_D108N_H123Y_A142N_A143G_D147Y_E155V_I156F),

(R26Q_L84F_A106V_D108N_H123Y_A142N_D147Y_E155V_I156F),

(E25M_R26G_L84F_A106V_R107P_D108N_H123Y_A142N_A143D_D147Y_E155V_I156F),

(R26C_L84F_A106V_R107H_D108N_H123Y_A142N_D147Y_E155V_I156F),

(L84F_A106V_D108N_H123Y_A142N_A143L_D147Y_E155V_I156F),

(R26G_L84F_A106V_D108N_H123Y_A142N_D147Y_E155V_I156F),

(E25A_R26G_L84F_A106V_R107N_D108N_H123Y_A142N_A143E_D147Y_E155V_I156F),

(R26G_L84F_A106V_R107H_D108N_H123Y_A142N_A143D_D147Y_E155V_I156F),

(A106V_D108N_A142N_D147Y_E155V),

(R26G_A106V_D108N_A142N_D147Y_E155V),

(E25D_R26G_A106V_R107K_D108N_A142N_A143G_D147Y_E155V),

(R26G_A106V_D108N_R107H_A142N_A143D_D147Y_E155V),

(E25D_R26G_A106V_D108N_A142N_D147Y_E155V),

(A106V_R107K_D108N_A142N_D147Y_E155V),

(A106V_D108N_A142N_A143G_D147Y_E155V),

(A106V_D108N_A142N_A143L_D147Y_E155V),

(H36L_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N),

(N37T_P48T_M70L_L84F_A106V_D108N_H123Y_D147Y_I49V_E155V_I156F),

(N37S_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F_K161T),

(H36L_L84F_A106V_D108N_H123Y_D147Y_Q154H_E155V_I156F),

(N72S_L84F_A106V_D108N_H123Y_S146R_D147Y_E155V_I156F),

(H36L_P48L_L84F_A106V_D108N_H123Y_E134G_D147Y_E155V_I156F),

(H36L_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F_K157N),

(H36L_L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F),

(L84F_A106V_D108N_H123Y_S146R_D147Y_E155V_I156F_K161T),

(N37S_R51H_D77G_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F),

(R51L_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F_K157N),

(D24G_Q71R_L84F_H96L_A106V_D108N_H123Y_D147Y_E155V_I156F_K160E),

(H36L_G67V_L84F_A106V_D108N_H123Y_S146T_D147Y_E155V_I156F),

(Q71L_L84F_A106V_D108N_H123Y_L137M_A143E_D147Y_E155V_I156F),

(E25G_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F_Q159L),

(L84F_A91T_F104I_A106V_D108N_H123Y_D147Y_E155V_I156F),

(N72D_L84F_A106V_D108N_H123Y_G125A_D147Y_E155V_I156F),

(P48S_L84F_S97C_A106V_D108N_H123Y_D147Y_E155V_I156F),

(W23G_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F),

(D24G_P48L_Q71R_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F_Q159L),

(L84F_A106V_D108N_H123Y_A142N_D147Y_E155V_I156F),

(H36L_R51L_L84F_A106V_D108N_H123Y_A142N_S146C_D147Y_E155V_I156F_K157N), (N37S_L84F_A106V_D108N_H123Y_A142N_D147Y_E155V_I156F_K161T),

(L84F_A106V_D108N_D147Y_E155V_I156F),

(R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N_K161T),

(L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K161T),

(L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N_K160E_K161T),

(L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N_K160E),

(R74Q_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F),

(R74A_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F),

(L84F_A106V_D108N_H123Y_D147Y_E155V_I156F),

(R74Q_L84F_A106V_D108N_H123Y_D147Y_E155V_I156F),

(L84F_R98Q_A106V_D108N_H123Y_D147Y_E155V_I156F),

(L84F_A106V_D108N_H123Y_R129Q_D147Y_E155V_I156F),

(P48S_L84F_A106V_D108N_H123Y_A142N_D147Y_E155V_I156F),

(P48S_A142N),

(P48T_I49V_L84F_A106V_D108N_H123Y_A142N_D147Y_E155V_I156F L157N),

(P48T_I49V_A142N),

(H36L_P48S_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N),

(H36L_P48S_R51L_L84F_A106V_D108N_H123Y_S146C_A142N_D147Y_E155V_I156F (H36L_P48T_I49V_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N),

(H36L_P48T_I49V_R51L_L84F_A106V_D108N_H123Y_A142N_S146C_D147Y_E155V_I156F_K157N),

(H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N),

(H36L_P48A_R51L_L84F_A106V_D108N_H123Y_A142N_S146C_D147Y_E155V_I156F_K157N),

(H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146C_A142N_D147Y_E155V_I156F_K157N),

(W23L_H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N),

(W23R_H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_E155V_I156F_K157N),

(W23L_H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146R_D147Y_E155V_I156F_K161T),

(H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_R152H_E155V_I156F_K157N),

(H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_R152P_E155V_I156F K157N),

(W23L_H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_R152P_E155V_I156F_K157N),

(W23L_H36L_P48A_R51L_L84F_A106V_D108N_H123Y_A142A_S146C_D147Y_E155V_I156F_K157N),

(W23L_H36L_P48A_R51L_L84F_A106V_D108N_H123Y_A142A_S146C_D147Y_R152P_E155V_I156F_K157N),

(W23L_H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146R_D147Y_E155V_I156F_K161T),

(W23R_H36L_P48A_R51L_L84F_A106V_D108N_H123Y_S146C_D147Y_R152P_E155V_I156F_K157N),

(H36L_P48A_R51L_L84F_A106V_D108N_H123Y_A142N_S146C_D147Y_R152P_E155V_I156F_K157N).

[0536] In certain embodiments, the fusion proteins provided herein comprise one or more features that improve the base editing activity of the fusion proteins. For example, any of the fusion proteins provided herein may comprise a Cas9 domain that has reduced nuclease activity. In some embodiments, any of the fusion proteins provided herein may have a Cas9 domain that does not have nuclease activity (dCas9), or a Cas9 domain that cuts one strand of a duplexed DNA molecule, referred to as a Cas9 nickase (nCas9).

Adenosine Deaminases

[0537] In some embodiments, the fusion proteins of the invention comprise an adenosine deaminase. In some embodiments, the adenosine deaminases provided herein are capable of deaminating adenine. In some embodiments, the adenosine deaminases provided herein are capable of deaminating adenine in a deoxyadenosine residue of DNA. The adenosine deaminase may be derived from any suitable organism (e.g., E. coli). In some embodiments, the adenine deaminase is a naturally-occurring adenosine deaminase that includes one or more mutations corresponding to any of the mutations provided herein (e.g., mutations in ecTadA). One of skill in the art will be able to identify the corresponding residue in any homologous protein, e.g., by sequence alignment and determination of homologous residues. Accordingly, one of skill in the art would be able to generate mutations in any naturally-occurring adenosine deaminase (e.g., having homology to ecTadA) that corresponds to any of the mutations described herein, e.g., any of the mutations identified in ecTadA. In some embodiments, the adenosine deaminase is from a prokaryote. In some embodiments, the adenosine deaminase is from a bacterium. In some embodiments, the adenosine deaminase is from Escherichia coli, Staphylococcus aureus, Salmonella typhi, Shewanella putrefaciens, Haemophilus influenzae, Caulobacter crescentus, or Bacillus subtilis. In some embodiments, the adenosine deaminase is from E. coli.

[0538] Also provided herein are adenosine deaminase variants that have increased efficiency (>50-60%) and specificity. In particular, the adenosine deaminase variants described herein are more likely to edit a desired base within a polynucleotide, and are less likely to edit bases that are not intended to be altered (i.e., “bystanders”). In some embodiments, the nucleobase editors of the invention are adenosine deaminase variants comprising an alteration in the following sequence:

TABLE-US-00065 MSEVEFSHEYWMRHALTLAKRARDEREVPVG AVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGA MIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQV FNAQKKAQSSTD
(also termed TadA*7.10). In particular embodiments, TadA*7.10 comprises one or more of the following alterations: Y147T, Y147R, Q154S, Y123H, V82S, T166R, and Q154R. The alteration Y123H refers to the alteration H123Y in TadA*7.10 reverted back to Y123H TadA (wt). In other embodiments, the TadA*7.10 comprises the following alterations: Y147R+Q154R+Y123H; Y147R+Q154R+I76Y; Y147R+Q154R+T166R; Y147T+Q154R; Y147T+Q154S; V82S+Q154S; and Y123H+Y147R+Q154R+I76Y. In particular embodiments, an adenosine deaminase variant comprises a deletion of the C-terminus beginning at residue 149, 150, 151, 152, 153, 154, 155, 156, and 157.

[0539] In other embodiments, a base editor is a monomer comprising an adenosine deaminase variant (e.g., TadA*8) comprising one or more of the following alterations: Y147T, Y147R, Q154S, Y123H, V82S, T166R, Q154R. In other embodiments, the adenosine deaminase variant (TadA*8) is a monomer comprising the following alterations: Y147R+Q154R+Y123H; Y147R+Q154R+I76Y; Y147R+Q154R+T166R; Y147T+Q154R; Y147T+Q154S; V82S+Q154S; and Y123H+Y147R+Q154R+I76Y. In other embodiments, a base editor is a heterodimer comprising a wild-type adenosine deaminase and an adenosine deaminase variant (e.g., TadA*8) comprising one or more of the following alterations Y147T, Y147R, Q154S, Y123H, V82S, T166R, Q154R. In other embodiments, the base editor is a heterodimer comprising a TadA*7.10 domain and an adenosine deaminase variant domain (e.g., TadA*8) comprising the following alterations: Y147R+Q154R+Y123H; Y147R+Q154R+I76Y; Y147R+Q154R+T166R; Y147T+Q154R; Y147T+Q154S; V82S+Q154S; and Y123H+Y147R+Q154R+I76Y.

[0540] In one embodiment, an adenosine deaminase is a TadA*8 that comprises or consists essentially of the following sequence or a fragment thereof having adenosine deaminase activity:

TABLE-US-00066 MSEVEFSHEYWMRHALTLAKRARDEREVPVG AVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGA MIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCTFFRMPRQV FNAQKKAQSSTD

[0541] In some embodiments, the TadA*8 is truncated. In some embodiments, the truncated TadA*8 is missing 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 N-terminal amino acid residues relative to the full length TadA*8. In some embodiments, the truncated TadA*8 is missing 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 C-terminal amino acid residues relative to the full length TadA*8. In some embodiments the adenosine deaminase variant is a full-length TadA*8.

[0542] In some embodiments the TadA*8 is TadA*8.1, TadA*8.2, TadA*8.3, TadA*8.4, TadA*8.5, TadA*8.6, TadA*8.6, TadA*8.7, TadA*8.8, TadA*8.9, TadA*8.10, TadA*8.11, TadA*8.12, TadA*8.13, TadA*8.14, TadA*8.15, TadA*8.16, TadA*8.17, TadA*8.18, TadA*8.19, TadA*8.20, TadA*8.21, TadA*8.22, TadA*8.23, TadA*8.24, TadA*8.25, or TadA*8.26.

[0543] In other embodiments, a base editor of the disclosure is a monomer comprising an adenosine deaminase variant (e.g., TadA*8) comprising one or more of the following alterations: R26C, V88A, A109S, T111R, D119N, H122N, Y147D, F149Y, T166I and/or D167N, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In other embodiments, the adenosine deaminase variant (TadA*8) is a monomer comprising a combination of alterations selected from the group of: R26C+A109S+T111R+D119N+H122N+Y147D+F149Y+T166I+D167N; V88A+A109S+T111R+D119N+H122N+F149Y+T166I+D167N; R26C+A109S+T111R+D119N+H122N+F149Y+T166I+D167N; V88A+T111R+D119N+F149Y; and A109S+T111R+D119N+H122N+Y147D+F149Y+T166I+D167N, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA.

[0544] In other embodiments, a base editor is a heterodimer comprising a wild-type adenosine deaminase and an adenosine deaminase variant (e.g., TadA*8) comprising one or more of the following alterations R26C, V88A, A109S, T111R, D119N, H122N, Y147D, F149Y, T166I and/or D167N, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In other embodiments, the base editor is a heterodimer comprising a wild-type adenosine deaminase and an adenosine deaminase variant domain (e.g., TadA*8) comprising a combination of alterations selected from the group of: R26C+A109S+T111R+D119N+H122N+Y147D+F149Y+T166I+D167N; V88A+A109S+T111R+D119N+H122N+F149Y+T166I+D167N; R26C+A109S+T111R+D119N+H122N+F149Y+T166I+D167N; V88A+T111R+D119N+F149Y; and A109S+T111R+D119N+H122N+Y147D+F149Y+T166I+D167N, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA.

[0545] In other embodiments, a base editor is a heterodimer comprising a TadA*7.10 domain and an adenosine deaminase variant (e.g., TadA*8) comprising one or more of the following alterations R26C, V88A, A109S, T111R, D119N, H122N, Y147D, F149Y, T166I and/or D167N, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA. In other embodiments, the base editor is a heterodimer comprising a TadA*7.10 domain and an adenosine deaminase variant domain (e.g., TadA*8) comprising a combination of alterations selected from the group of: R26C+A109S+T111R+D119N+H122N+Y147D+F149Y+T166I+D167N; V88A+A109S+T111R+D119N+H122N+F149Y+T166I+D167N; R26C+A109S+T111R+D119N+H122N+F149Y+T166I+D167N; V88A+T111R+D119N+F149Y; and A109S+T111R+D119N+H122N+Y147D+F149Y+T166I+D167N, relative to TadA*7.10, the TadA reference sequence, or a corresponding mutation in another TadA.

[0546] In some embodiments, the TadA*8 is a variant as shown in Table 5A. Table 5A shows certain amino acid position numbers in the TadA amino acid sequence and the amino acids present in those positions in the TadA-7.10 adenosine deaminase. Table 5A also shows amino acid changes in TadA variants relative to TadA-7.10 following phage-assisted non-continuous evolution (PANCE) and phage-assisted continuous evolution (PACE), as described in M. Richter et al., 2020, Nature Biotechnology, doi.org/10.1038/s41587-020-0453-z, the entire contents of which are incorporated by reference herein. In some embodiments, the TadA*8 is TadA*8a, TadA*8b, TadA*8c, TadA*8d, or TadA*8e. In some embodiments, the TadA*8 is TadA*8e.

TABLE-US-00067 TABLE 5A Additional TadA*8 Variants TadA amino acid number TadA 26 88 109 111 119 122 147 149 166 167 TadA-7.10 R V A T D H Y F T D PANCE 1 R PANCE 2 S/T R PACE TadA-8a C S R N N D Y I N TadA-8b A S R N N Y I N TadA-8c C S R N N Y I N TadA-8d A R N Y TadA-8e S R N N D Y I N

[0547] In some embodiments, the adenosine deaminases provided herein are capable of deaminating adenine. In some embodiments, the adenosine deaminases provided herein are capable of deaminating adenine in a deoxyadenosine residue of DNA. In some embodiments, the adenine deaminase is a naturally-occurring adenosine deaminase that includes one or more mutations corresponding to any of the mutations provided herein (e.g., mutations in ecTadA). One of skill in the art will be able to identify the corresponding residue in any homologous protein, e.g., by sequence alignment and determination of homologous residues. Accordingly, one of skill in the art would be able to generate mutations in any naturally-occurring adenosine deaminase (e.g., having homology to ecTadA) that corresponds to any of the mutations described herein, e.g., any of the mutations identified in ecTadA.

[0548] In some embodiments, adenosine deaminase base editors with specificity for NGT PAM may be generated as provided in Table 5B below.

TABLE-US-00068 TABLE 5B NGT PAM variants NGTN variant D1135 S1136 G1218 E1219 A1322R R1335 T1337 Variant LRKIQK L R K I — Q K 1 Variant LRSVQK L R S V — Q K 2 Variant LRSVQL L R S V — Q L 3 Variant LRKIRQK L R K I R Q K 4 Variant LRSVRQK L R S V R Q K 5 Variant LRSVRQL L R S V R Q L 6

[0549] In some embodiments the NGTN variant is variant 1. In some embodiments, the NGTN variant is variant 2. In some embodiments, the NGTN variant is variant 3. In some embodiments, the NGTN variant is variant 4. In some embodiments, the NGTN variant is variant 5. In some embodiments, the NGTN variant is variant 6.

[0550] In one embodiment, a fusion protein of the invention comprises a wild-type TadA that is linked to an adenosine deaminase variant described herein (e.g., TadA*8), which is linked to Cas9 nickase. In particular embodiments, the fusion proteins comprise a single TadA*8 domain (e.g., provided as a monomer). In other embodiments, the base editor comprises TadA*8 and TadA (wt), which are capable of forming heterodimers. Exemplary TadA amino acid sequences include the following:

TABLE-US-00069 MSEVEFSHEYWMRHALTLAKRAWDEREVPVG AVLVHNNRVIGEGWNRPIGRHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTLEPCVMCAGA MIHSRIGRVVFGARDAKTGAAGSLMDVLHHP GMNHRVEITEGILADECAALLSDFFRMRRQE IKAQKKAQSSTD TadA*7.10: MSEVEFSHEYWMRHALTLAKRARDEREVPVG AVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGA MIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQV FNAQKKAQSSTD TadA*8: MSEVEFSHEYWMRHALTLAKRARDEREVPVG AVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGA MIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCTFFRMPRQV FNAQKKAQSSTD.

[0551] In some embodiments, the adenosine deaminase comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the amino acid sequences set forth in any of the adenosine deaminases provided herein. It should be appreciated that adenosine deaminases provided herein may include one or more mutations (e.g., any of the mutations provided herein). The disclosure provides any deaminase domains with a certain percent identity plus any of the mutations or combinations thereof described herein. In some embodiments, the adenosine deaminase comprises an amino acid sequence that has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, or more mutations compared to a reference sequence, or any of the adenosine deaminases provided herein. In some embodiments, the adenosine deaminase comprises an amino acid sequence that has at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 110, at least 120, at least 130, at least 140, at least 150, at least 160, or at least 170 identical contiguous amino acid residues as compared to any one of the amino acid sequences known in the art or described herein.

[0552] In particular embodiments, a TadA*8 comprises one or more mutations at any of the following positions shown in bold. In other embodiments, a TadA*8 comprises one or more mutations at any of the positions shown with underlining:

TABLE-US-00070 MSEVEFSHEY WMRHALTLAK RARDEREVPV GAVLVLNNRV IGEGWNRAIG  50 LHDPTAHAEI MALRQGGLVM QN RLIDATL Y TFEPCVMC AGAMIHSRIG 100 RVVFGVRNAK TGAAGSLMDV LH PGMNHRV EITEGILADE CAALLC FFR 150 MPR VFNAQK KAQSS D

[0553] For example, the TadA*8 comprises alterations at amino acid position 82 and/or 166 (e.g., V82S, T166R) alone or in combination with any one or more of the following Y147T, Y147R, Q154S, Y123H, and Q154R. In particular embodiments, the following alterations are made Y147R+Q154R+Y123H; Y147R+Q154R+I76Y; Y147R+Q154R+T166R; Y147T+Q154R; Y147T+Q154S; V82S+Q154S; and Y123H+Y147R+Q154R+I76Y. In some embodiments, the adenosine deaminase is TadA*8, which comprises or consists essentially of the following sequence or a fragment thereof having adenosine deaminase activity:

TABLE-US-00071 MSEVEFSHEY WMRHALTLAK RARDEREVPV GAVLVLNNRV IGEGWNRAIG LHDPTAHAEI MALRQGGLVM QNYRLIDATL YVTFEPCVMC AGAMIHSRIG RVVFGVRNAK TGAAGSLMDV LHYPGMNHRV EITEGILADE CAALLCTFFR MPRQVFNAQK KAQSSTD

[0554] In some embodiments, the TadA*8 is truncated. In some embodiments, the truncated TadA*8 is missing 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 N-terminal amino acid residues relative to the full length TadA*8. In some embodiments, the truncated TadA*8 is missing 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 6, 17, 18, 19, or 20 C-terminal amino acid residues relative to the full length TadA*8. In some embodiments the adenosine deaminase variant is a full-length TadA*8.

[0555] In one embodiment, a fusion protein of the invention comprises a wild-type TadA is linked to an adenosine deaminase variant described herein (e.g., TadA*8), which is linked to Cas9 nickase. In particular embodiments, the fusion proteins comprise a single TadA*8 domain (e.g., provided as a monomer). In other embodiments, the base editor comprises TadA*8 and TadA (wt), which are capable of forming heterodimers.

C to T Editing

[0556] In some embodiments, a base editor disclosed herein comprises a fusion protein comprising deaminase capable of deaminating a target cytidine (C) base of a polynucleotide to produce uridine (U), which has the base pairing properties of thymine. In some embodiments, for example where the polynucleotide is double-stranded (e.g., DNA), the uridine base can then be substituted with a thymidine base (e.g., by cellular repair machinery) to give rise to a C:G to a T:A transition. In other embodiments, deamination of a C to U in a nucleic acid by a base editor cannot be accompanied by substitution of the U to a T.

[0557] The deamination of a target C in a polynucleotide to give rise to a U is a non-limiting example of a type of base editing that can be executed by a base editor described herein. In another example, a base editor comprising a cytidine deaminase domain can mediate conversion of a cytosine (C) base to a guanine (G) base. For example, a U of a polynucleotide produced by deamination of a cytidine by a cytidine deaminase domain of a base editor can be excised from the polynucleotide by a base excision repair mechanism (e.g., by a uracil DNA glycosylase (UDG) domain), producing an abasic site. The nucleobase opposite the abasic site can then be substituted (e.g., by base repair machinery) with another base, such as a C, by for example a translesion polymerase. Although it is typical for a nucleobase opposite an abasic site to be replaced with a C, other substitutions (e.g., A, G or T) can also occur.

[0558] Accordingly, in some embodiments a base editor described herein comprises a deamination domain (e.g., cytidine deaminase domain) capable of deaminating a target C to a U in a polynucleotide. Further, as described below, the base editor can comprise additional domains which facilitate conversion of the U resulting from deamination to, in some embodiments, a T or a G. For example, a base editor comprising a cytidine deaminase domain can further comprise a uracil glycosylase inhibitor (UGI) domain to mediate substitution of a U by a T, completing a C-to-T base editing event. In another example, a base editor can incorporate a translesion polymerase to improve the efficiency of C-to-G base editing, since a translesion polymerase can facilitate incorporation of a C opposite an abasic site (i.e., resulting in incorporation of a G at the abasic site, completing the C-to-G base editing event).

[0559] A base editor comprising a cytidine deaminase as a domain can deaminate a target C in any polynucleotide, including DNA, RNA and DNA-RNA hybrids. Typically, a cytidine deaminase catalyzes a C nucleobase that is positioned in the context of a single-stranded portion of a polynucleotide. In some embodiments, the entire polynucleotide comprising a target C can be single-stranded. For example, a cytidine deaminase incorporated into the base editor can deaminate a target C in a single-stranded RNA polynucleotide. In other embodiments, a base editor comprising a cytidine deaminase domain can act on a double-stranded polynucleotide, but the target C can be positioned in a portion of the polynucleotide which at the time of the deamination reaction is in a single-stranded state. For example, in embodiments where the NAGPB domain comprises a Cas9 domain, several nucleotides can be left unpaired during formation of the Cas9-gRNA-target DNA complex, resulting in formation of a Cas9 “R-loop complex”. These unpaired nucleotides can form a bubble of single-stranded DNA that can serve as a substrate for a single-strand specific nucleotide deaminase enzyme (e.g., cytidine deaminase).

[0560] In some embodiments, a cytidine deaminase of a base editor can comprise all or a portion of an apolipoprotein B mRNA editing complex (APOBEC) family deaminase. APOBEC is a family of evolutionarily conserved cytidine deaminases. Members of this family are C-to-U editing enzymes. The N-terminal domain of APOBEC like proteins is the catalytic domain, while the C-terminal domain is a pseudocatalytic domain. More specifically, the catalytic domain is a zinc dependent cytidine deaminase domain and is important for cytidine deamination. APOBEC family members include APOBEC1, APOBEC2, APOBEC3A, APOBEC3B, APOBEC3C, APOBEC3D (“APOBEC3E” now refers to this), APOBEC3F, APOBEC3G, APOBEC3H, APOBEC.fwdarw., and Activation-induced (cytidine) deaminase. In some embodiments, the APOBEC family members include rAPOBEC1, BE4 in which the APOBEC1 sequence is replaced with rAPOBEC1, PpAPOBEC1, BE4 in which the APOBEC1 sequence is replaced with PpABOBEC1, PpAPOBEC1 containing an H122A substitution, BE4 in which the APOBEC1 sequence is replaced with PpAPOBEC1 containing an H122A substitution; BE4 in which the APOBEC1 sequence is replaced with RrA3F containing an F130L substitution; BE4 in which the APOBEC1 sequence is replaced with AmAPOBEC1; BE4 in which the APOBEC1 sequence is replaced with SsAPOBEC2. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of an APOBEC1 deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC2 deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of is an APOBEC3 deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of an APOBEC3A deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC3B deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC3C deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC3D deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC3E deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC3F deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC3G deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC3H deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of APOBEC4 deaminase. In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of activation-induced deaminase (AID). In some embodiments a deaminase incorporated into a base editor comprises all or a portion of cytidine deaminase 1 (CDA1). It should be appreciated that a base editor can comprise a deaminase from any suitable organism (e.g., a human or a rat). In some embodiments, a deaminase domain of a base editor is from a human, chimpanzee, gorilla, monkey, cow, dog, rat, or mouse. In some embodiments, the deaminase domain of the base editor is derived from rat (e.g., rat APOBEC1). In some embodiments, the deaminase domain of the base editor is human APOBEC1. In some embodiments, the deaminase domain of the base editor is pmCDA1.

[0561] The amino acid and nucleic acid sequences of PmCDA1 are shown herein below.

TABLE-US-00072 >tr|A5H718|A5H718_PETMA Cytosine dcaininase OS = Petromyzon marinus OX = 7757 PE = 2 SV = 1 amino acid sequence: MTDAEYVRIHEKLDIYTFKKQFFNNKKSVSH RCYVLFELKRRGERRACFWGYAVNKPQSGTE RGIHAEIFSIRKVEEYLRDNPGQFTINWYSS WSPCADCAEKILEWYNQELRGNGHTLKIWAC KLYYEKNARNQIGLWNLRDNGVGLNVMVSEH YQCCRKIFIQSSHNQLNENRWLEKTLKRAEK RRSELSIMIQVKILHTTKSPAV Nucleic acid sequence: >EF094822.1  Petromvzon marinus isolate PmCDA.21 cytosine deaminase mRNA, complete cds: TGACACGACACAGCCGTGTATATGAGGAAGG GTAGCTGGATGGGGGGGGGGGGAATACGTTC AGAGAGGACATTAGCGAGCGTCTTGTTGGTG GCCTTGAGTCTAGACACCTGCAGACATGACC GACGCTGAGTACGTGAGAATCCATGAGAAGT TGGACATCTACACGTTTAAGAAACAGTTTTT CAACAACAAAAAATCCGTGTCGCATAGATGC TACGTTCTCTTTGAATTAAAACGACGGGGTG AACGTAGAGCGTGTTTTTGGGGCTATGCTGT GAATAAACCACAGAGCGGGACAGAACGTGGA ATTCACGCCGAAATCTTTAGCATTAGAAAAG TCGAAGAATACCTGCGCGACAACCCCGGACA ATTCACGATAAATTGGTACTCATCCTGGAGT CCTTGTGCAGATTGCGCTGAAAAGATCTTAG AATGGTATAACCAGGAGCTGCGGGGGAACGG CCACACTTTGAAAATCTGGGCTTGCAAACTC TATTACGAGAAAAATGCGAGGAATCAAATTG GGCTGTGGAACCTCAGAGATAACGGGGTTGG GTTGAATGTAATGGTAAGTGAACACTACCAA TGTTGCAGGAAAATATTCATCCAATCGTCGC ACAATCAATTGAATGAGAATAGATGGCTTGA GAAGACTTTGAAGCGAGCTGAAAAACGACGG AGCGAGTTGTCCATTATGATTCAGGTAAAAA TACTCCACACCACTAAGAGTCCTGCTGTTTA AGAGGCTATGCGGATGGTTTTC

[0562] The amino acid and nucleic acid sequences of the coding sequence (CDS) of human activation-induced cytidine deaminase (AID) are shown below.

TABLE-US-00073 >tr|Q6QJ80|Q6QJ80_HUMAN Activation-induced cytidine deaminase OS = Homo sapiens OX = 9606 GN = AICDA PE = 2 SV = 1 amino acid sequence: MDSLLMNRRKFLYQFKNVRWAKGRRETYLC YVVKRRDSATSFSLDFGYLRNKNGCHVELL FLRYISDWDLDPGRCYRVTWFTSWSPCYDC ARHVADFLRGNPNLSLRIFTARLYFCEDRK AEPEGLRRLHRAGVQIAIMTFKAPV

[0563] The amino acid and nucleic acid sequences of the coding sequence (CDS) of human activation-induced cytidine deaminase (AID) are shown below.

TABLE-US-00074 >tr|Q6QJ80|Q6QJ80_HUMAN Activation-induced cytidine deaminase OS = Homo sapiens OX = 9606 GN = AICDA PE = 2 SV = 1 amino acid sequence: MDSLLMNRRKFLYQFKNVRWAKGRRETYLCYVVKRRDSAT SFSLDFGYLRNKNGCHVELLFLRYISDWDLDPGRCYRVTW FTSWSPCYDCARHVADFLRGNPNLSLRIFTARLYFCEDRK AEPEGLRRLHRAGVQIAIMTFKAPV Nucleic acid sequence: >NG_011588.1:5001-15681 Homo sapiens activation induced cytidine deaminase (AICDA), RefSeqGene (LRG_17) on chromosome 12: AGAGAACCATCATTAATTGAAGTGAGATTTTTCTGGCCTG AGACTTGCAGGGAGGCAAGAAGACACTCTGGACACCACTA TGGACAGGTAAAGAGGCAGTCTTCTCGTGGGTGATTGCAC TGGCCTTCCTCTCAGAGCAAATCTGAGTAATGAGACTGGT AGCTATCCCTTTCTCTCATGTAACTGTCTGACTGATAAGA TCAGCTTGATCAATATGCATATATATTTTTTGATCTGTCT CCTTTTCTTCTATTCAGATCTTATACGCTGTCAGCCCAAT TCTTTCTGTTTCAGACTTCTCTTGATTTCCCTCTTTTTCA TGTGGCAAAAGAAGTAGTGCGTACAATGTACTGATTCGTC CTGAGATTTGTACCATGGTTGAAACTAATTTATGGTAATA ATATTAACATAGCAAATCTTTAGAGACTCAAATCATGAAA AGGTAATAGCAGTACTGTACTAAAAACGGTAGTGCTAATT TTCGTAATAATTTTGTAAATATTCAACAGTAAAACAACTT GAAGACACACTTTCCTAGGGAGGCGTTACTGAAATAATTT AGCTATAGTAAGAAAATTTGTAATTTTAGAAATGCCAAGC ATTCTAAATTAATTGCTTGAAAGTCACTATGATTGTGTCC ATTATAAGGAGACAAATTCATTCAAGCAAGTTATTTAATG TTAAAGGCCCAATTGTTAGGCAGTTAATGGCACTTTTACT ATTAACTAATCTTTCCATTTGTTCAGACGTAGCTTAACTT ACCTCTTAGGTGTGAATTTGGTTAAGGTCCTCATAATGTC TTTATGTGCAGTTTTTGATAGGTTATTGTCATAGAACTTA TTCTATTCCTACATTTATGATTACTATGGATGTATGAGAA TAACACCTAATCCTTATACTTTACCTCAATTTAACTCCTT TATAAAGAACTTACATTACAGAATAAAGATTTTTTAAAAA TATATTTTTTTGTAGAGACAGGGTCTTAGCCCAGCCGAGG CTGGTCTCTAAGTCCTGGCCCAAGCGATCCTCCTGCCTGG GCCTCCTAAAGTGCTGGAATTATAGACATGAGCCATCACA TCCAATATACAGAATAAAGATTTTTAATGGAGGATTTAAT GTTCTTCAGAAAATTTTCTTGAGGTCAGACAATGTCAAAT GTCTCCTCAGTTTACACTGAGATTTTGAAAACAAGTCTGA GCTATAGGTCCTTGTGAAGGGTCCATTGGAAATACTTGTT CAAAGTAAAATGGAAAGCAAAGGTAAAATCAGCAGTTGAA ATTCAGAGAAAGACAGAAAAGGAGAAAAGATGAAATTCAA CAGGACAGAAGGGAAATATATTATCATTAAGGAGGACAGT ATCTGTAGAGCTCATTAGTGATGGCAAAATGACTTGGTCA GGATTATTTTTAACCCGCTTGTTTCTGGTTTGCACGGCTG GGGATGCAGCTAGGGTTCTGCCTCAGGGAGCACAGCTGTC CAGAGCAGCTGTCAGCCTGCAAGCCTGAAACACTCCCTCG GTAAAGTCCTTCCTACTCAGGACAGAAATGACGAGAACAG GGAGCTGGAAACAGGCCCCTAACCAGAGAAGGGAAGTAAT GGATCAACAAAGTTAACTAGCAGGTCAGGATCACGCAATT CATTTCACTCTGACTGGTAACATGTGACAGAAACAGTGTA GGCTTATTGTATTTTCATGTAGAGTAGGACCCAAAAATCC ACCCAAAGTCCTTTATCTATGCCACATCCTTCTTATCTAT ACTTCCAGGACACTTTTTCTTCCTTATGATAAGGCTCTCT CTCTCTCCACACACACACACACACACACACACACACACAC ACACACACACACAAACACACACCCCGCCAACCAAGGTGCA TGTAAAAAGATGTAGATTCCTCTGCCTTTCTCATCTACAC AGCCCAGGAGGGTAAGTTAATATAAGAGGGATTTATTGGT AAGAGATGATGCTTAATCTGTTTAACACTGGGCCTCAAAG AGAGAATTTCTTTTCTTCTGTACTTATTAAGCACCTATTA TGTGTTGAGCTTATATATACAAAGGGTTATTATATGCTAA TATAGTAATAGTAATGGTGGTTGGTACTATGGTAATTACC ATAAAAATTATTATCCTTTTAAAATAAAGCTAATTATTAT TGGATCTTTTTTAGTATTCATTTTATGTTTTTTATGTTTT TGATTTTTTAAAAGACAATCTCACCCTGTTACCCAGGCTG GAGTGCAGTGGTGCAATCATAGCTTTCTGCAGTCTTGAAC TCCTGGGCTCAAGCAATCCTCCTGCCTTGGCCTCCCAAAG TGTTGGGATACAGTCATGAGCCACTGCATCTGGCCTAGGA TCCATTTAGATTAAAATATGCATTTTAAATTTTAAAATAA TATGGCTAATTTTTACCTTATGTAATGTGTATACTGGCAA TAAATCTAGTTTGCTGCCTAAAGTTTAAAGTGCTTTCCAG TAAGCTTCATGTACGTGAGGGGAGACATTTAAAGTGAAAC AGACAGCCAGGTGTGGTGGCTCACGCCTGTAATCCCAGCA CTCTGGGAGGCTGAGGTGGGTGGATCGCTTGAGCCCTGGA GTTCAAGACCAGCCTGAGCAACATGGCAAAACGCTGTTTC TATAACAAAAATTAGCCGGGCATGGTGGCATGTGCCTGTG GTCCCAGCTACTAGGGGGCTGAGGCAGGAGAATCGTTGGA GCCCAGGAGGTCAAGGCTGCACTGAGCAGTGCTTGCGCCA CTGCACTCCAGCCTGGGTGACAGGACCAGACCTTGCCTCA AAAAAATAAGAAGAAAAATTAAAAATAAATGGAAACAACT ACAAAGAGCTGTTGTCCTAGATGAGCTACTTAGTTAGGCT GATATTTTGGTATTTAACTTTTAAAGTCAGGGTCTGTCAC CTGCACTACATTATTAAAATATCAATTCTCAATGTATATC CACACAAAGACTGGTACGTGAATGTTCATAGTACCTTTAT TCACAAAACCCCAAAGTAGAGACTATCCAAATATCCATCA ACAAGTGAACAAATAAACAAAATGTGCTATATCCATGCAA TGGAATACCACCCTGCAGTACAAAGAAGCTACTTGGGGAT GAATCCCAAAGTCATGACGCTAAATGAAAGAGTCAGACAT GAAGGAGGAGATAATGTATGCCATACGAAATTCTAGAAAA TGAAAGTAACTTATAGTTACAGAAAGCAAATCAGGGCAGG CATAGAGGCTCACACCTGTAATCCCAGCACTTTGAGAGGC CACGTGGGAAGATTGCTAGAACTCAGGAGTTCAAGACCAG CCTGGGCAACACAGTGAAACTCCATTCTCCACAAAAATGG GAAAAAAAGAAAGCAAATCAGTGGTTGTCCTGTGGGGAGG GGAAGGACTGCAAAGAGGGAAGAAGCTCTGGTGGGGTGAG GGTGGTGATTCAGGTTCTGTATCCTGACTGTGGTAGCAGT TTGGGGTGTTTACATCCAAAAATATTCGTAGAATTATGCA TCTTAAATGGGTGGAGTTTACTGTATGTAAATTATACCTC AATGTAAGAAAAAATAATGTGTAAGAAAACTTTCAATTCT CTTGCCAGCAAACGTTATTCAAATTCCTGAGCCCTTTACT TCGCAAATTCTCTGCACTTCTGCCCCGTACCATTAGGTGA CAGCACTAGCTCCACAAATTGGATAAATGCATTTCTGGAA AAGACTAGGGACAAAATCCAGGCATCACTTGTGCTTTCAT ATCAACCATGCTGTACAGCTTGTGTTGCTGTCTGCAGCTG CAATGGGGACTCTTGATTTCTTTAAGGAAACTTGGGTTAC CAGAGTATTTCCACAAATGCTATTCAAATTAGTGCTTATG ATATGCAAGACACTGTGCTAGGAGCCAGAAAACAAAGAGG AGGAGAAATCAGTCATTATGTGGGAACAACATAGCAAGAT ATTTAGATCATTTTGACTAGTTAAAAAAGCAGCAGAGTAC AAAATCACACATGCAATCAGTATAATCCAAATCATGTAAA TATGTGCCTGTAGAAAGACTAGAGGAATAAACACAAGAAT CTTAACAGTCATTGTCATTAGACACTAAGTCTAATTATTA TTATTAGACACTATGATATTTGAGATTTAAAAAATCTTTA ATATTTTAAAATTTAGAGCTCTTCTATTTTTCCATAGTAT TCAAGTTTGACAATGATCAAGTATTACTCTTTCTTTTTTT TTTTTTTTTTTTTTTTTTGAGATGGAGTTTTGGTCTTGTT GCCCATGCTGGAGTGGAATGGCATGACCATAGCTCACTGC AACCTCCACCTCCTGGGTTCAAGCAAAGCTGTCGCCTCAG CCTCCCGGGTAGATGGGATTACAGGCGCCCACCACCACAC TCGGCTAATGTTTGTATTTTTAGTAGAGATGGGGTTTCAC CATGTTGGCCAGGCTGGTCTCAAACTCCTGACCTCAGAGG ATCCACCTGCCTCAGCCTCCCAAAGTGCTGGGATTACAGA TGTAGGCCACTGCGCCCGGCCAAGTATTGCTCTTATACAT TAAAAAACAGGTGTGAGCCACTGCGCCCAGCCAGGTATTG CTCTTATACATTAAAAAATAGGCCGGTGCAGTGGCTCACG CCTGTAATCCCAGCACTTTGGGAAGCCAAGGCGGGCAGAA CACCCGAGGTCAGGAGTCCAAGGCCAGCCTGGCCAAGATG GTGAAACCCCGTCTCTATTAAAAATACAAACATTACCTGG GCATGATGGTGGGCGCCTGTAATCCCAGCTACTCAGGAGG CTGAGGCAGGAGGATCCGCGGAGCCTGGCAGATCTGCCTG AGCCTGGGAGGTTGAGGCTACAGTAAGCCAAGATCATGCC AGTATACTTCAGCCTGGGCGACAAAGTGAGACCGTAACAA AAAAAAAAAAATTTAAAAAAAGAAATTTAGATCAAGATCC AACTGTAAAAAGTGGCCTAAACACCACATTAAAGAGTTTG GAGTTTATTCTGCAGGCAGAAGAGAACCATCAGGGGGTCT TCAGCATGGGAATGGCATGGTGCACCTGGTTTTTGTGAGA TCATGGTGGTGACAGTGTGGGGAATGTTATTTTGGAGGGA CTGGAGGCAGACAGACCGGTTAAAAGGCCAGCACAACAGA TAAGGAGGAAGAAGATGAGGGCTTGGACCGAAGCAGAGAA GAGCAAACAGGGAAGGTACAAATTCAAGAAATATTGGGGG GTTTGAATCAACACATTTAGATGATTAATTAAATATGAGG ACTGAGGAATAAGAAATGAGTCAAGGATGGTTCCAGGCTG CTAGGCTGCTTACCTGAGGTGGCAAAGTCGGGAGGAGTGG CAGTTTAGGACAGGGGGCAGTTGAGGAATATTGTTTTGAT CATTTTGAGTTTGAGGTACAAGTTGGACACTTAGGTAAAG ACTGGAGGGGAAATCTGAATATACAATTATGGGACTGAGG AACAAGTTTATTTTATTTTTTGTTTCGTTTTCTTGTTGAA GAACAAATTTAATTGTAATCCCAAGTCATCAGCATCTAGA AGACAGTGGCAGGAGGTGACTGTCTTGTGGGTAAGGGTTT GGGGTCCTTGATGAGTATCTCTCAATTGGCCTTAAATATA AGCAGGAAAAGGAGTTTATGATGGATTCCAGGCTCAGCAG GGCTCAGGAGGGCTCAGGCAGCCAGCAGAGGAAGTCAGAG CATCTTCTTTGGTTTAGCCCAAGTAATGACTTCCTTAAAA AGCTGAAGGAAAATCCAGAGTGACCAGATTATAAACTGTA CTCTTGCATTTTCTCTCCCTCCTCTCACCCACAGCCTCTT GATGAACCGGAGGAAGTTTCTTTACCAATTCAAAAATGTC CGCTGGGCTAAGGGTCGGCGTGAGACCTACCTGTGCTACG TAGTGAAGAGGCGTGACAGTGCTACATCCTTTTCACTGGA CTTTGGTTATCTTCGCAATAAGGTATCAATTAAAGTCGGC TTTGCAAGCAGTTTAATGGTCAACTGTGAGTGCTTTTAGA GCCACCTGCTGATGGTATTACTTCCATCCTTTTTTGGCAT TTGTGTCTCTATCACATTCCTCAAATCCTTTTTTTTATTT CTTTTTCCATGTCCATGCACCCATATTAGACATGGCCCAA AATATGTGATTTAATTCCTCCCCAGTAATGCTGGGCACCC TAATACCACTCCTTCCTTCAGTGCCAAGAACAACTGCTCC CAAACTGTTTACCAGCTTTCCTCAGCATCTGAATTGCCTT TGAGATTAATTAAGCTAAAAGCATTTTTATATGGGAGAAT ATTATCAGCTTGTCCAAGCAAAAATTTTAAATGTGAAAAA CAAATTGTGTCTTAAGCATTTTTGAAAATTAAGGAAGAAG AATTTGGGAAAAAATTAACGGTGGCTCAATTCTGTCTTCC AAATGATTTCTTTTCCCTCCTACTCACATGGGTCGTAGGC CAGTGAATACATTCAACATGGTGATCCCCAGAAAACTCAG AGAAGCCTCGGCTGATGATTAATTAAATTGATCTTTCGGC TACCCGAGAGAATTACATTTCCAAGAGACTTCTTCACCAA AATCCAGATGGGTTTACATAAACTTCTGCCCACGGGTATC TCCTCTCTCCTAACACGCTGTGACGTCTGGGCTTGGTGGA ATCTCAGGGAAGCATCCGTGGGGTGGAAGGTCATCGTCTG GCTCGTTGTTTGATGGTTATATTACCATGCAATTTTCTTT GCCTACATTTGTATTGAATACATCCCAATCTCCTTCCTAT TCGGTGACATGACACATTCTATTTCAGAAGGCTTTGATTT TATCAAGCACTTTCATTTACTTCTCATGGCAGTGCCTATT ACTTCTCTTACAATACCCATCTGTCTGCTTTACCAAAATC TATTTCCCCTTTTCAGATCCTCCCAAATGGTCCTCATAAA CTGTCCTGCCTCCACCTAGTGGTCCAGGTATATTTCCACA ATGTTACATCAACAGGCACTTCTAGCCATTTTCCTTCTCA AAAGGTGCAAAAAGCAACTTCATAAACACAAATTAAATCT TCGGTGAGGTAGTGTGATGCTGCTTCCTCCCAACTCAGCG CACTTCGTCTTCCTCATTCCACAAAAACCCATAGCCTTCC TTCACTCTGCAGGACTAGTGCTGCCAAGGGTTCAGCTCTA CCTACTGGTGTGCTCTTTTGAGCAAGTTGCTTAGCCTCTC TGTAACACAAGGACAATAGCTGCAAGCATCCCCAAAGATC ATTGCAGGAGACAATGACTAAGGCTACCAGAGCCGCAATA AAAGTCAGTGAATTTTAGCGTGGTCCTCTCTGTCTCTCCA GAACGGCTGCCACGTGGAATTGCTCTTCCTCCGCTACATC TCGGACTGGGACCTAGACCCTGGCCGCTGCTACCGCGTCA CCTGGTTCACCTCCTGGAGCCCCTGCTACGACTGTGCCCG ACATGTGGCCGACTTTCTGCGAGGGAACCCCAACCTCAGT CTGAGGATCTTCACCGCGCGCCTCTACTTCTGTGAGGACC GCAAGGCTGAGCCCGAGGGGCTGCGGCGGCTGCACCGCGC CGGGGTGCAAATAGCCATCATGACCTTCAAAGGTGCGAAA GGGCCTTCCGCGCAGGCGCAGTGCAGCAGCCCGCATTCGG GATTGCGATGCGGAATGAATGAGTTAGTGGGGAAGCTCGA GGGGAAGAAGTGGGCGGGGATTCTGGTTCACCTCTGGAGC CGAAATTAAAGATTAGAAGCAGAGAAAAGAGTGAATGGCT CAGAGACAAGGCCCCGAGGAAATGAGAAAATGGGGCCAGG GTTGCTTCTTTCCCCTCGATTTGGAACCTGAACTGTCTTC TACCCCCATATCCCCGCCTTTTTTTCCTTTTTTTTTTTTT GAAGATTATTTTTACTGCTGGAATACTTTTGTAGAAAACC ACGAAAGAACTTTCAAAGCCTGGGAAGGGCTGCATGAAAA TTCAGTTCGTCTCTCCAGACAGCTTCGGCGCATCCTTTTG GTAAGGGGCTTCCTCGCTTTTTAAATTTTCTTTCTTTCTC TACAGTCTTTTTTGGAGTTTCGTATATTTCTTATATTTTC TTATTGTTCAATCACTCTCAGTTTTCATCTGATGAAAACT TTATTTCTCCTCCACATCAGCTTTTTCTTCTGCTGTTTCA CCATTCAGAGCCCTCTGCTAAGGTTCCTTTTCCCTCCCTT TTCTTTCTTTTGTTGTTTCACATCTTTAAATTTCTGTCTC TCCCCAGGGTTGCGTTTCCTTCCTGGTCAGAATTCTTTTC TCCTTTTTTTTTTTTTTTTTTTTTTTTTTTAAACAAACAA ACAAAAAACCCAAAAAAACTCTTTCCCAATTTACTTTCTT CCAACATGTTACAAAGCCATCCACTCAGTTTAGAAGACTC TCCGGCCCCACCGACCCCCAACCTCGTTTTGAAGCCATTC ACTCAATTTGCTTCTCTCTTTCTCTACAGCCCCTGTATGA GGTTGATGACTTACGAGACGCATTTCGTACTTTGGGACTT TGATAGCAACTTCCAGGAATGTCACACACGATGAAATATC TCTGCTGAAGACAGTGGATAAAAAACAGTCCTTCAAGTCT TCTCTGTTTTTATTCTTCAACTCTCACTTTCTTAGAGTTT ACAGAAAAAATATTTATATACGACTCTTTAAAAAGATCTA TGTCTTGAAAATAGAGAAGGAACACAGGTCTGGCCAGGGA CGTGCTGCAATTGGTGCAGTTTTGAATGCAACATTGTCCC CTACTGGGAATAACAGAACTGCAGGACCTGGGAGCATCCT AAAGTGTCAACGTTTTTCTATGACTTTTAGGTAGGATGAG AGCAGAAGGTAGATCCTAAAAAGCATGGTGAGAGGATCAA ATGTTTTTATATCAACATCCTTTATTATTTGATTCATTTG AGTTAACAGTGGTGTTAGTGATAGATTTTTCTATTCTTTT CCCTTGACGTTTACTTTCAAGTAACACAAACTCTTCCATC AGGCCATGATCTATAGGACCTCCTAATGAGAGTATCTGGG TGATTGTGACCCCAAACCATCTCTCCAAAGCATTAATATC CAATCATGCGCTGTATGTTTTAATCAGCAGAAGCATGTTT TTATGTTTGTACAAAAGAAGATTGTTATGGGTGGGGATGG AGGTATAGACCATGCATGGTCACCTTCAAGCTACTTTAAT AAAGGATCTTAAAATGGGCAGGAGGACTGTGAACAAGACA CCCTAATAATGGGTTGATGTCTGAAGTAGCAAATCTTCTG GAAACGCAAACTCTTTTAAGGAAGTCCCTAATTTAGAAAC ACCCACAAACTTCACATATCATAATTAGCAAACAATTGGA AGGAAGTTGCTTGAATGTTGGGGAGAGGAAAATCTATTGG CTCTCGTGGGTCTCTTCATCTCAGAAATGCCAATCAGGTC AAGGTTTGCTACATTTTGTATGTGTGTGATGCTTCTCCCA AAGGTATATTAACTATATAAGAGAGTTGTGACAAAACAGA ATGATAAAGCTGCGAACCGTGGCACACGCTCATAGTTCTA GCTGCTTGGGAGGTTGAGGAGGGAGGATGGCTTGAACACA GGTGTTCAAGGCCAGCCTGGGCAACATAACAAGATCCTGT CTCTCAAAAAAAAAAAAAAAAAAAAGAAAGAGAGAGGGCC GGGCGTGGTGGCTCACGCCTGTAATCCCAGCACTTTGGGA GGCCGAGCCGGGCGGATCACCTGTGGTCAGGAGTTTGAGA CCAGCCTGGCCAACATGGCAAAACCCCGTCTGTACTCAAA ATGCAAAAATTAGCCAGGCGTGGTAGCAGGCACCTGTAAT CCCAGCTACTTGGGAGGCTGAGGCAGGAGAATCGCTTGAA CCCAGGAGGTGGAGGTTGCAGTAAGCTGAGATCGTGCCGT TGCACTCCAGCCTGGGCGACAAGAGCAAGACTCTGTCTCA GAAAAAAAAAAAAAAAAGAGAGAGAGAGAGAAAGAGAACA ATATTTGGGAGAGAAGGATGGGGAAGCATTGCAAGGAAAT TGTGCTTTATCCAACAAAATGTAAGGAGCCAATAAGGGAT CCCTATTTGTCTCTTTTGGTGTCTATTTGTCCCTAACAAC TGTCTTTGACAGTGAGAAAAATATTCAGAATAACCATATC CCTGTGCCGTTATTACCTAGCAACCCTTGCAATGAAGATG AGCAGATCCACAGGAAAACTTGAATGCACAACTGTCTTAT TTTAATCTTATTGTACATAAGTTTGTAAAAGAGTTAAAAA TTGTTACTTCATGTATTCATTTATATTTTATATTATTTTG CGTCTAATGATTTTTTATTAACATGATTTCCTTTTCTGAT ATATTGAAATGGAGTCTCAAAGCTTCATAAATTTATAACT TTAGAAATGATTCTAATAACAACGTATGTAATTGTAACAT TGCAGTAATGGTGCTACGAAGCCATTTCTCTTGATTTTTA GTAAACTTTTATGACAGCAAATTTGCTTCTGGCTCACTTT CAATCAGTTAAATAAATGATAAATAATTTTGGAAGCTGTG AAGATAAAATACCAAATAAAATAATATAAAAGTGATTTAT ATGAAGTTAAAATAAAAAATCAGTATGATGGAATAAACTT G

[0564] Other exemplary deaminases that can be fused to Cas9 according to aspects of this disclosure are provided below. In embodiments, the deaminases are activation-induced deaminases (AID). In some embodiments, the deaminases are APOBEC deaminases. It should be understood that, in some embodiments, the active domain of the respective sequence can be used, e.g., the domain without a localizing signal (nuclear localization sequence, without nuclear export signal, cytoplasmic localizing signal).

TABLE-US-00075 Human AID: MDSLLMNRRKFLYQFKNVRWAKGRRETYLCYVVKRRDSATSFSLDFGYLR NKNGCHVELLFLRYISDWDLDPGRCYRVTWFTSWSPCYDCARHVADFLRG NPNLSLRIFTARLYFCEDRKAEPEGLRRLHRAGVQIAIMTFKDYFYCWNT FVENHERTFKAWEGLHENSVRLSRQLRRILLPLYEVDDLRDAFRTLGL (underline: nuclear localization sequence; double underline: nuclear export signal) Mouse AID: MDSLLMKQKKFLYHFKNVRWAKGRHETYLCYVVKRRDSATSCSLDFGHLR NKSGCHVELLFLRYISDWDLDPGRCYRVTWFTSWSPCYDCARHVAEFLRW NPNLSLRIFTARLYFCEDRKAEPEGLRRLHRAGVQIGIMTFKDYFYCWNT FVENRERTFKAWEGLHENSVRLTRQLRRILLPLYEVDDLRDAFRMLGF (underline: nuclear localization sequence; double underline: nuclear export signal) Canine AID: MDSLLMKQRKFLYHFKNVRWAKGRHETYLCYVVKRRDSATSFSLDFGHLR NKSGCHVELLFLRYISDWDLDPGRCYRVTWFTSWSPCYDCARHVADFLRG YPNLSLRIFAARLYFCEDRKAEPEGLRRLHRAGVQIAIMTFKDYFYCWNT FVENREKTFKAWEGLHENSVRLSRQLRRILLPLYEVDDLRDAFRTLGL (underline: nuclear localization sequence; double underline: nuclear export signal) Bovine AID: MDSLLKKQRQFLYQFKNVRWAKGRHETYLCYVVKRRDSPTSFSLDFGHLR NKAGCHVELLFLRYISDWDLDPGRCYRVTWFTSWSPCYDCARHVADFLRG YPNLSLRIFTARLYFCDKERKAEPEGLRRLHRAGVQIAIMTFKDYFYCWN TFVENHERTFKAWEGLHENSVRLSRQLRRILLPLYEVDDLRDAFRTLGL (underline: nuclear localization sequence; double underline: nuclear export signal) Rat AID: MAVGSKPKAALVGPHWERERIWCFLCSTGLGTQQTGQTSRWLRPAATQDP VSPPRSLLMKQRKFLYHFKNVRWAKGRHETYLCYVVKRRDSATSFSLDFG YLRNKSGCHVELLFLRYISDWDLDPGRCYRVTWFTSWSPCYDCARHVADF LRGNPNLSLRIFTARLTGWGALPAGLMSPARPSDYFYCWNTFVENHERTF KAWEGLHENSVRLSRRLRRILLPLYEVDDLRDAFRTLGL (underline: nuclear localization sequence; double underline: nuclear export signal) clAID (Canis lupus familiaris): MDSLLMKQRKFLYHFKNVRWAKGRHETYLCYVVKRRDSATSFSLDFGHLR NKSGCHVELLFLRYISDWDLDPGRCYRVTWFTSWSPCYDCARHVADFLRG YPNLSLRIFAARLYFCEDRKAEPEGLRRLHRAGVQIAIMTFKDYFYCWNT FVENREKTFKAWEGLHENSVRLSRQLRRILLPLYEVDDLRDAFRTLGL btAID (Bos Taurus): MDSLLKKQRQFLYQFKNVRWAKGRHETYLCYVVKRRDSPTSFSLDFGHLR NKAGCHVELLFLRYISDWDLDPGRCYRVTWFTSWSPCYDCARHVADFLRG YPNLSLRIFTARLYFCDKERKAEPEGLRRLHRAGVQIAIMTFKDYFYCWN TFVENHERTFKAWEGLHENSVRLSRQLRRILLPLYEVDDLRDAFRTLGL mAID (Mus musculus): MDSLLMNRRKFLYQFKNVRWAKGRRETYLCYVVKRRDSATSFSLDFGYLR NKNGCHVELLFLRYISDWDLDPGRCYRVTWFTSWSPCYDCARHVADFLRG NPNLSLRIFTARLYFCEDRKAEPEGLRRLHRAGVQIAIMTFKDYFYCWNT FVENHERTFKAWEGLHENSVRLSRQLRRILLPLYEVDDLRDAFRTLGL RrA3F (Rhinopithecus roxellana) MKPQIRDHRPNPMEAMYPHIFYFHFENLEKAYGRNETWLCFTVEIIKQYL PVPWKKGVFRNQVDPETHCHAEKCFLSWFCNNTLSPKKNYQVTWYTSWSP CPECAGEVAEFLAEHSNVKLTIYTARLYY WDTDYQEGLRSLSEEGASVE IMDYEDFQYCWENFVYDDGEPFKRWKGLKYNFQSLTRRLREILQ
In the above RrA3F sequence, the Phenylalanine (F) amino acid residue at position 130, which is substituted with leucine (L), i.e., an F130L mutation, as described herein (e.g., Examples 3 and 4), is designated in bold and underline

TABLE-US-00076 amAPOBEC-1 (Alligator mississippiensis) MADSSEKMRGQYISRDTFEKNYKPIDGTKEAHLLCEIKWGKYGKPWLHWC QNQRMNIHAEDYFMNNIFKAKKHPVHCYVTWYLSWSPCADCASKIVKFLE ERPYLKLTIYVAQLYYHTEEENRKGLRLLRSKKVIIRVMDISDYNYCWKV FVSNQNGNEDYWPLQFDPWVKENYSRLLDIFWESKCRSPNPW rAPOBEC-1 (Rattus norvegicus): MSSETGPVAVDPTLRRRIEPHEFEVFFDPRELRKETCLLYEINWGGRHSI WRHTSQNTNKHVEVNFIEKETTERYFCPNTRCSITWFLSWSPCGECSRAI TEFLSRYPHVTLFIYIARLYHHADPRNRQGLRDLISSGVTIQIMTEQESG YCWRNFVNYSPSNEAHWPRYPHLWVRLYVLELYCIILGLPPCLNILRRKQ PQLTFFTIALQSCHYQRLPPHILWATGLK maAPOBEC-1 (Mesocricetus auratus): MSSETGPVVVDPILRRRIEPHEFDAFFDQGELRKETCLLYEIRWGGRHNI WRHTGQNTSRHVEINFIEKFTSERYFYPSTRCSIVWFLSWSPCGECSKAI TEFLSGHPNVTLFIYAARLYHHTDQRNRQGLRDLISRGVTIRIMTEQEYC YCWRNEVNYPPSNEVYWPRYPNLWMRLYALELYCIHLGLPPCLKIKRRHQ YPLTFFRLNLQSCHYQRIPPHILWATGFI ppAPOBEC-1 (Pongo pygmaeus): MTSEKGPSTGDPILRRRIESWEEDVEYDPRELRKETCLLYEIKWGMSRKI WRSSGKNITNHVEVNFIKKFTSERREHSSISCSITWELSWSPCWECSQAI REFLSQHPGVTLVIYVARLFWHMDQRNRQGLRDLVNSGVTIQIMRASEYY HCWRNEVNYPPGDEAHWPQYPPLWMMLYALELHCIILSLPPCLKISRRWQ NHLAFFRLHLQNCHYQTIPPHILLATGLIHPSVTWR ppAPOBEC-1 H122A (Pongo pygmaeus) MTSEKGPSTGDPILRRRIESWEEDVEYDPRELRKETCLLYEIKWGMSRKI WRSSGKNITNHVEVNFIKKFTSERREHSSISCSITWELSWSPCWECSQAI REFLSQHPGVTLVIYVARLFWAMDQRNRQGLRDLVNSGVTIQIMRASEYY HCWRNEVNYPPGDEAHWPQYPPLWMMLYALELHCIILSLPPCLKISRRWQ NHLAFFRLHLQNCHYQTIPPHILLATGLIHPSVTWRLK
In the above ppAPOBEC1 sequence, the amino acid residue at position 122 reflects an H122A mutation in the above, non-mutated ppAPOBEC1 sequence, as described herein (e.g., Examples 3 and 4).

TABLE-US-00077 ocAPOBEC1 (Oryctolagus cuniculus): MASEKGPSNKDYTLRRRIEPWEFEVFFDPQELRKEACLLYEIKWGASSKTWRSSGKNTTNHVEVNFLE KLTSEGRLGPSTCCSITWFLSWSPCWECSMAIREFLSQHPGVTLIIFVARLFQHMDRRNRQGLKDLVT SGVIVRVMSVSEYCYCWENEVNYPPGKAAQWPRYPPRWMLMYALELYCIILGLPPCLKISRRHQKQLT FESLTPQYCHYKMIPPYILLATGLLQPSVPWR mdAPOBEC-1 (Monodelphis domestica): MNSKTGPSVGDATLRRRIKPWEFVAFFNPQELRKETCLLYEIKWGNQNIWRHSNQNTSQHAEINFMEK FTAERHENSSVRCSITWFLSWSPCWECSKAIRKFLDHYPNVTLAIFISRLYWHMDQQHRQGLKELVHS GVTIQIMSYSEYHYCWRNFVDYPQGEEDYWPKYPYLWIMLYVLELHCIILGLPPCLKISGSHSNQLAL FSLDLQDCHYQKIPYNVLVATGLVQPFVTWR ppAPOBEC-2 (Pongo pygmaeus): MAQKEEAAAATEAASQNGEDLENLDDPEKLKELIELPPFEIVTGERLPANFFKFQFRNVEYSSGRNKT FLCYVVEAQGKGGQVQASRGYLEDEHAAAHAEEAFFNTILPAFDPALRYNVTWYVSSSPCAACADRII KTLSKTKNLRLLILVGRLFMWEELEIQDALKKLKEAGCKLRIMKPQDFEYVWQNFVEQEEGESKAFQP WEDIQENFLYYEEKLADILK btAPOBEC-2 (Bos Taurus): MAQKEEAAAAAEPASQNGEEVENLEDPEKLKELIELPPFEIVTGERLPAHYFKFQFRNVEYSSGRNKT FLCYVVEAQSKGGQVQASRGYLEDEHATNHAEEAFFNSIMPTFDPALRYMVTWYVSSSPCAACADRIV KTLNKTKNLRLLILVGRLFMWEEPEIQAALRKLKEAGCRLRIMKPQDFEYIWQNFVEQEEGESKAFEP WEDIQENFLYYEEKLADILK ssAPOBEC-2 (Sus scrofa) MDPQRLRQWPGPGPASRGGYGQRPRIRNPEEWFHELSPRTFSFHFRNLRFASGRNRSYICCQVEGKNC FFQGIFQNQVPPDPPCHAELCFLSWFQSWGLSPDEHYYVTWFISWSPCCECAAKVAQFLEENRNVSLS LSAARLYYFWKSESREGLRRLSDLGAQVGIMSFQDFQHCWNNFVHNLGMPFQPWKKLHKNYQRLVTEL KQILREEPATYGSPQAQGKVRIGSTAAGLRHSHSHTRSEAHLRPNHSSRQHRILNPPREARARTCVLV DASWICYR mAPOBEC-3-(1) (Mus musculus): MQPQRLGPRAGMGPFCLGCSHRKCYSPIRNLISQETFKFHFKNLGYAKGRKDTFLCYEVTRKDCDSPV SLHHGVFKNKDNIHAEICFLYWFHDKVLKVLSPREEFKITWYMSWSPCFECAEQIVRFLATHHNLSLD IFSSRLYNVQDPETQQNLCRLVQEGAQVAAMDLYEFKKCWKKFVDNGGRRFRPWKRLLTNFRYQDSKL QEILRPCYISVPSSSSSTLSNICLTKGLPETRFWVEGRRMDPLSEEEFYSQFYNQRVKHLCYYHRMKP YLCYQLEQFNGQAPLKGCLLSEKGKQHAEILFLDKIRSMELSQVTITCYLTWSPCPNCAWQLAAFKRD RPDLILHIYTSRLYFHWKRPFQKGLCSLWQSGILVDVMDLPQFTDCWTNFVNPKRPFWPWKGLEIISR RTQRRLRRIKESWGLQDLVNDFGNLQLGPPMS Mouse APOBEC-3-(2): MGPFCLGCSHRKCYSPIRNLISQETFKFHFKNLGYAKGRKDTFLCYEVTRKDCDSPVSLHHGVFKNKD NIHAEICFLYWFHDKVLKVLSPREEFKITWYMSWSPCFECAEQIVRFLATHHNLSLDIFSSRLYNVQD PETQQNLCRLVQEGAQVAAMDLYEFKKCWKKFVDNGGRRFRPWKRLLTNFRYQDSKLQEILRPCYIPV PSSSSSTLSNICLTKGLPETRFCVEGRRMDPLSEEEFYSQFYNQRVKHLCYYHRMKPYLCYQLEQFNG QAPLKGCLLSEKGKQHAEILFLDKIRSMELSQVTITCYLTWSPCPNCAWQLAAFKRDRPDLILHIYTS RLYFHWKRPFQKGLCSLWQSGILVDVMDLPQFTDCWTNFVNPKRPFWPWKGLEIISRRTQRRLRRIKE SWGLQDLVNDFGNLQLGPPMS (italic: nucleic acid editing domain) Rat APOBEC-3: MGPFCLGCSHRKCYSPIRNLISQETFKFHFKNRLRYAIDRKDTFLCYEVTRKDCDSPVSLHHGVFKNK DNIHAEICFLYWFHDKVLKVLSPREEFKITWYMSWSPCFECAEQVLRFLATHHNLSLDIFSSRLYNIR DPENQQNLCRLVQEGAQVAAMDLYEFKKCWKKFVDNGGRRFRPWKKLLTNFRYQDSKLQEILRPCYIP VPSSSSSTLSNICLTKGLPETRFCVERRRVHLLSEEEFYSQFYNQRVKHLCYYHGVKPYLCYQLEQFN GQAPLKGCLLSEKGKQHAEILFLDKIRSMELSQVIITCYLTWSPCPNCAWQLAAFKRDRPDLILHIYT SRLYFHWKRPFQKGLCSLWQSGILVDVMDLPQFTDCWTNFVNPKRPFWPWKGLEIISRRTQRRLHRIK ESWGLQDLVNDFGNLQLGPPMS (italic: nucleic acid editing domain) hAPOBEC-3A (Homo sapiens): MEASPASGPRHLMDPHIFTSNFNNGIGRHKTYLCYEVERLDNGTSVKMDQHRGFLHNQAKNLLCGFYG RHAELRFLDLVPSLQLDPAQIYRVTWFISWSPCFSWGCAGEVRAFLQENTHVRLRIFAARIYDYDPLY KEALQMLRDAGAQVSIMTYDEFKHCWDTFVDHQGCPFQPWDGLDEHSQALSGRLRAILQNQGN hAPOBEC-3F (Homo sapiens): MKPHFRNTVERMYRDTFSYNFYNRPILSRRNTVWLCYEVKTKGPSRPRLDAKIFRGQVYSQPEHHAEM CFLSWFCGNQLPAYKCFQITWFVSWTPCPDCVAKLAEFLAEHPNVTLTISAARLYYYWERDYRRALCR LSQAGARVKIMDDEEFAYCWENFVYSEGQPFMPWYKFDDNYAFLHRTLKEILRNPMEAMYPHIFYFHF KNLRKAYGRNESWLCFTMEVVKHHSPVSWKRGVFRNQVDPETHCHAERCFLSWFCDDILSPNTNYEVT WYTSWSPCPECAGEVAEFLARHSNVNLTIFTARLYYFWDTDYQEGLRSLSQEGASVEIMGYKDFKYCW ENFVYNDDEPFKPWKGLKYNFLFLDSKLQEILE Rhesus macaque APOBEC-3G: MVEPMDPRTFVSNFNNRPILSGLNTVWLCCEVKTKDPSGPPLDAKIFQGKVYSKAKYHPEMRFLRWFH KWRQLHHDQEYKVTWYVSWSPCTRCANSVATFLAKDPKVTLTIFVARLYYFWKPDYQQALRILCQKRG GPHATMKIMNYNEFQDCWNKFVDGRGKPFKPRNNLPKHYTLLQATLGELLRHLMDPGTFTSNFNNKPW VSGQHETYLCYKVERLHNDTWVPLNQHRGFLRNQAPNIHGFPKGRHAELCFLDLIPFWKLDGQQYRVT CFTSWSPCFSCAQEMAKFISNNEHVSLCIFAARIYDDQGRYQEGLRALHRDGAKIAMMNYSEFEYCWD TFVDRQGRPFQPWDGLDEHSQALSGRLRAI (italic: nucleic acid editing domain; underline: cytoplasmic localization signal) Chimpanzee APOBEC-3G: MKPHFRNPVERMYQDTFSDNFYNRPILSHRNTVWLCYEVKTKGPSRPPLDAKIFRGQVYSKLKYHPEM RFFHWFSKWRKLHRDQEYEVTWYISWSPCTKCTRDVATFLAEDPKVTLTIFVARLYYFWDPDYQEALR SLCQKRDGPRATMKIMNYDEFQHCWSKFVYSQRELFEPWNNLPKYYILLHIMLGEILRHSMDPPTFTS NFNNELWVRGRHETYLCYEVERLHNDTWVLLNQRRGFLCNQAPHKHGFLEGRHAELCFLDVIPFWKLD LHQDYRVTCFTSWSPCFSCAQEMAKFISNNKHVSLCIFAARIYDDQGRCQEGLRTLAKAGAKISIMTY SEFKHCWDTFVDHQGCPFQPWDGLEEHSQALSGRLRAILQNQGN (italic: nucleic acid editing domain; underline: cytoplasmic localization signal) Green monkey APOBEC-3G: MNPQIRNMVEQMEPDIFVYYFNNRPILSGRNTVWLCYEVKTKDPSGPPLDANIFQGKLYPEAKDHPEM KFLHWFRKWRQLHRDQEYEVTWYVSWSPCTRCANSVATFLAEDPKVTLTIFVARLYYFWKPDYQQALR ILCQERGGPHATMKIMNYNEFQHCWNEFVDGQGKPFKPRKNLPKHYTLLHATLGELLRHVMDPGTFTS NFNNKPWVSGQRETYLCYKVERSHNDTWVLLNQHRGFLRNQAPDRHGFPKGRHAELCFLDLIPFWKLD DQQYRVTCFTSWSPCFSCAQKMAKFISNNKHVSLCIFAARIYDDQGRCQEGLRTLHRDGAKIAVMNYS EFEYCWDTFVDRQGRPFQPWDGLDEHSQALSGRLRAI (italic: nucleic acid editing domain; underline: cytoplasmic localization signal) Human APOBEC-3G: MKPHFRNTVERMYRDTFSYNFYNRPILSRRNTVWLCYEVKTKGPSRPPLDAKIFRGQVYSELKYHPEM RFFHWFSKWRKLHRDQEYEVTWYISWSPCTKCTRDMATFLAEDPKVTLTIFVARLYYFWDPDYQEALR SLCQKRDGPRATMKIMNYDEFQHCWSKFVYSQRELFEPWNNLPKYYILLHIMLGEILRHSMDPPTFTF NFNNEPWVRGRHETYLCYEVERMHNDTWVLLNQRRGFLCNQAPHKHGFLEGRHAELCFLDVIPFWKLD LDQDYRVTCFTSWSPCFSCAQEMAKFISKNKHVSLCIFTARIYDDQGRCQEGLRTLAEAGAKISIMTY SEFKHCWDTFVDHQGCPFQPWDGLDEHSQDLSGRLRAILQNQEN (italic: nucleic acid editing domain; underline: cytoplasmic localization signal) Human APOBEC-3F: MKPHFRNTVERMYRDTFSYNFYNRPILSRRNTVWLCYEVKTKGPSRPRLDAKIFRGQVYSQPEHHAEM CFLSWFCGNQLPAYKCFQITWFVSWTPCPDCVAKLAEFLAEHPNVTLTISAARLYYYWERDYRRALCR LSQAGARVKIMDDEEFAYCWENFVYSEGQPFMPWYKFDDNYAFLHRTLKEILRNPMEAMYPHIFYFHF KNLRKAYGRNESWLCFTMEVVKHHSPVSWKRGVFRNQVDPETHCHAERCFLSWFCDDILSPNTNYEVT WYTSWSPCPECAGEVAEFLARHSNVNLTIFTARLYYFWDTDYQEGLRSLSQEGASVEIMGYKDFKYCW ENFVYNDDEPFKPWKGLKYNFLFLDSKLQEILE (italic: nucleic acid editing domain) Human APOBEC-3B: MNPQIRNPMERMYRDTFYDNFENEPILYGRSYTWLCYEVKIKRGRSNLLWDTGVFRGQVYFKPQYHAE MCFLSWFCGNQLPAYKCFQITWFVSWTPCPDCVAKLAEFLSEHPNVTLTISAARLYYYWERDYRRALC RLSQAGARVTIMDYEEFAYCWENFVYNEGQQFMPWYKFDENYAFLHRTLKEILRYLMDPDTFTFNFNN DPLVLRRRQTYLCYEVERLDNGTWVLMDQHMGFLCNEAKNLLCGFYGRHAELRFLDLVPSLQLDPAQI YRVTWFISWSPCFSWGCAGEVRAFLQENTHVRLRIFAARIYDYDPLYKEALQMLRDAGAQVSIMTYDE FEYCWDTFVYRQGCPFQPWDGLEEHSQALSGRLRAILQNQGN (italic: nucleic acid editing domain) Rat APOBEC-3B: MQPQGLGPNAGMGPVCLGCSHRRPYSPIRNPLKKLYQQTFYFHFKNVRYAWGRKNNFLCYEVNGMDCA LPVPLRQGVFRKQGHIHAELCFIYWFHDKVLRVLSPMEEFKVTWYMSWSPCSKCAEQVARFLAAHRNL SLAIFSSRLYYYLRNPNYQQKLCRLIQEGVHVAAMDLPEFKKCWNKFVDNDGQPFRPWMRLRINFSFY DCKLQEIFSRMNLLREDVFYLQFNNSHRVKPVQNRYYRRKSYLCYQLERANGQEPLKGYLLYKKGEQH VEILFLEKMRSMELSQVRITCYLTWSPCPNCARQLAAFKKDHPDLILRIYTSRLYFWRKKFQKGLCTL WRSGIHVDVMDLPQFADCWTNFVNPQRPFRPWNELEKNSWRIQRRLRRIKESWGL Bovine APOBEC-3B: DGWEVAFRSGTVLKAGVLGVSMTEGWAGSGHPGQGACVWTPGTRNTMNLLREVLFKQQFGNQPRVPAP YYRRKTYLCYQLKQRNDLTLDRGCFRNKKQRHAERFIDKINSLDLNPSQSYKIICYITWSPCPNCANE LVNFITRNNHLKLEIFASRLYFHWIKSFKMGLQDLQNAGISVAVMTHTEFEDCWEQFVDNQSRPFQPW DKLEQYSASIRRRLQRILTAPI Chimpanzee APOBEC-3B: MNPQIRNPMEWMYQRTFYYNFENEPILYGRSYTWLCYEVKIRRGHSNLLWDTGVFRGQMYSQPEHHAE MCFLSWFCGNQLSAYKCFQITWFVSWTPCPDCVAKLAKFLAEHPNVTLTISAARLYYYWERDYRRALC RLSQAGARVKIMDDEEFAYCWENFVYNEGQPFMPWYKFDDNYAFLHRTLKEIIRHLMDPDTFTFNFNN DPLVLRRHQTYLCYEVERLDNGTWVLMDQHMGFLCNEAKNLLCGFYGRHAELRFLDLVPSLQLDPAQI YRVTWFISWSPCFSWGCAGQVRAFLQENTHVRLRIFAARIYDYDPLYKEALQMLRDAGAQVSIMTYDE FEYCWDTFVYRQGCPFQPWDGLEEHSQALSGRLRAILQVRASSLCMVPHRPPPPPQSPGPCLPLCSEP PLGSLLPTGRPAPSLPFLLTASFSFPPPASLPPLPSLSLSPGHLPVPSFHSLTSCSIQPPCSSRIRET EGWASVSKEGRDLG Human APOBEC-3C: MNPQIRNPMKAMYPGTFYFQFKNLWEANDRNETWLCFTVEGIKRRSVVSWKTGVFRNQVDSETHCHAE RCFLSWFCDDILSPNTKYQVTWYTSWSPCPDCAGEVAEFLARHSNVNLTIFTARLYYFQYPCYQEGLR SLSQEGVAVEIMDYEDFKYCWENFVYNDNEPFKPWKGLKTNFRLLKRRLRESLQ (italic: nucleic acid editing domain) Gorilla APOBEC-3C MNPQIRNPMKAMYPGTFYFQFKNLWEANDRNETWLCFTVEGIKRRSVVSWKTGVFRNQVDSETHCHAE RCFLSWECDDILSPNTNYQVTWYTSWSPCPECAGEVAEFLARHSNVNLTIFTARLYYFQDTDYQEGLR SLSQEGVAVKIMDYKDFKYCWENFVYNDDEPFKPWKGLKYNFRFLKRRLQEILE (italic: nucleic acid editing domain) Human APOBEC-3A: MEASPASGPRHLMDPHIFTSNFNNGIGRHKTYLCYEVERLDNGTSVKMDQHRGFLHNQAKNLLCGFYG RHAELRFLDLVPSLQLDPAQIYRVTWFISWSPCFSWGCAGEVRAFLQENTHVRLRIFAARIYDYDPLY KEALQMLRDAGAQVSIMTYDEFKHCWDTFVDHQGCPFQPWDGLDEHSQALSGRLRAILQNQGN (italic: nucleic acid editing domain) Rhesus macaque APOBEC-3A: MDGSPASRPRHLMDPNTFTFNFNNDLSVRGRHQTYLCYEVERLDNGTWVPMDERRGFLCNKAKNVPCG DYGCHVELRFLCEVPSWQLDPAQTYRVTWFISWSPCFRRGCAGQVRVFLQENKHVRLRIFAARIYDYD PLYQEALRTLRDAGAQVSIMTYEEFKHCWDTFVDRQGRPFQPWDGLDEHSQALSGRLRAILQNQGN (italic: nucleic acid editing domain) Bovine APOBEC-3A: MDEYTFTENFNNQGWPSKTYLCYEMERLDGDATIPLDEYKGFVRNKGLDQPEKPCHAELYFLGKIHSW NLDRNQHYRLTCFISWSPCYDCAQKLTTFLKENHHISLHILASRIYTHNRFGCHQSGLCELQAAGARI TIMTFEDFKHCWETFVDHKGKPFQPWEGLNVKSQALCTELQAILKTQQN (italic: nucleic acid editing domain) Human APOBEC-3H: MALLTAETFRLQFNNKRRLRRPYYPRKALLCYQLTPQNGSTPTRGYFENKKKCHAEICFINEIKSMGL DETQCYQVTCYLTWSPCSSCAWELVDFIKAHDHLNLGIFASRLYYHWCKPQQKGLRLLCGSQVPVEVM GFPKFADCWENFVDHEKPLSFNPYKMLEELDKNSRAIKRRLERIKIPGVRAQGRYMDILCDAEV (italic: nucleic acid editing domain) Rhesus macaque APOBEC-3H: MALLTAKTFSLQFNNKRRVNKPYYPRKALLCYQLTPQNGSTPTRGHLKNKKKDHAEIRFINKIKSMGL DETQCYQVTCYLTWSPCPSCAGELVDFIKAHRHLNLRIFASRLYYHWRPNYQEGLLLLCGSQVPVEVM GLPEFTDCWENFVDHKEPPSFNPSEKLEELDKNSQAIKRRLERIKSRSVDVLENGLRSLQLGPVTPSS SIRNSR Human APOBEC-3D: MNPQIRNPMERMYRDTFYDNFENEPILYGRSYTWLCYEVKIKRGRSNLLWDTGVFRGPVLPKRQSNHR QEVYFRFENHAEMCFLSWFCGNRLPANRRFQITWFVSWNPCLPCVVKVTKFLAEHPNVTLTISAARLY YYRDRDWRWVLLRLHKAGARVKIMDYEDFAYCWENFVCNEGQPFMPWYKFDDNYASLHRTLKEILRNP MEAMYPHIFYFHFKNLLKACGRNESWLCFTMEVTKHHSAVFRKRGVFRNQVDPETHCHAERCFLSWFC DDILSPNTNYEVTWYTSWSPCPECAGEVAEFLARHSNVNLTIFTARLCYFWDTDYQEGLCSLSQEGAS VKIMGYKDFVSCWKNFVYSDDEPFKPWKGLQTNFRLLKRRLREILQ (italic: nucleic acid editing domain) Human APOBEC-1: MTSEKGPSTGDPTLRRRIEPWEFDVFYDPRELRKEACLLYEIKWGMSRKIWRSSGKNTTNHVEVNFIK KFTSERDFHPSMSCSITWFLSWSPCWECSQAIREFLSRHPGVTLVIYVARLFWHMDQQNRQGLRDLVN SGVTIQIMRASEYYHCWRNFVNYPPGDEAHWPQYPPLWMMLYALELHCIILSLPPCLKISRRWQNHLT FFRLHLQNCHYQTIPPHILLATGLIHPSVAWR Mouse APOBEC-1: MSSETGPVAVDPTLRRRIEPHEFEVFFDPRELRKETCLLYEINWGGRHSVWRHTSQNTSNHVEVNFLE KFTTERYFRPNTRCSITWFLSWSPCGECSRAITEFLSRHPYVTLFIYIARLYHHTDQRNRQGLRDLIS SGVTIQIMTEQEYCYCWRNFVNYPPSNEAYWPRYPHLWVKLYVLELYCIILGLPPCLKILRRKQPQLT FFTITLQTCHYQRIPPHLLWATGLK Rat APOBEC-1: MSSETGPVAVDPTLRRRIEPHEFEVFFDPRELRKETCLLYEINWGGRHSIWRHTSQNTNKHVEVNFIE KFTTERYFCPNTRCSITWFLSWSPCGECSRAITEFLSRYPHVTLFIYIARLYHHADPRNRQGLRDLIS SGVTIQIMTEQESGYCWRNFVNYSPSNEAHWPRYPHLWVRLYVLELYCIILGLPPCLNILRRKQPQLT FFTIALQSCHYQRLPPHILWATGLK Human APOBEC-2: MAQKEEAAVATEAASQNGEDLENLDDPEKLKELIELPPFEIVTGERLPANFFKFQFRNVEYSSGRNKT FLCYVVEAQGKGGQVQASRGYLEDEHAAAHAEEAFFNTILPAFDPALRYNVTWYVSSSPCAACADRII KTLSKTKNLRLLILVGRLFMWEEPEIQAALKKLKEAGCKLRIMKPQDFEYVWQNFVEQEEGESKAFQP WEDIQENFLYYEEKLADILK Mouse APOBEC-2: MAQKEEAAEAAAPASQNGDDLENLEDPEKLKELIDLPPFEIVTGVRLPVNFFKFQFRNVEYSSGRNKT FLCYVVEVQSKGGQAQATQGYLEDEHAGAHAEEAFFNTILPAFDPALKYNVTWYVSSSPCAACADRIL KTLSKTKNLRLLILVSRLFMWEEPEVQAALKKLKEAGCKLRIMKPQDFEYIWQNFVEQEEGESKAFEP WEDIQENFLYYEEKLADILK Rat APOBEC-2: MAQKEEAAEAAAPASQNGDDLENLEDPEKLKELIDLPPFEIVTGVRLPVNFFKFQFRNVEYSSGRNKT FLCYVVEAQSKGGQVQATQGYLEDEHAGAHAEEAFFNTILPAFDPALKYNVTWYVSSSPCAACADRIL KTLSKTKNLRLLILVSRLFMWEEPEVQAALKKLKEAGCKLRIMKPQDFEYLWQNFVEQEEGESKAFEP WEDIQENFLYYEEKLADILK Bovine APOBEC-2: MAQKEEAAAAAEPASQNGEEVENLEDPEKLKELIELPPFEIVTGERLPAHYFKFQFRNVEYSSGRNKT FLCYVVEAQSKGGQVQASRGYLEDEHATNHAEEAFFNSIMPTFDPALRYMVTWYVSSSPCAACADRIV KTLNKTKNLRLLILVGRLFMWEEPEIQAALRKLKEAGCRLRIMKPQDFEYIWQNFVEQEEGESKAFEP WEDIQENFLYYEEKLADILK Petromyzon marinus CDA1 (pmCDA1): MTDAEYVRIHEKLDIYTFKKQFFNNKKSVSHRCYVLFELKRRGERRACFWGYAVNKPQSGTERGIHAE IFSIRKVEEYLRDNPGQFTINWYSSWSPCADCAEKILEWYNQELRGNGHTLKIWACKLYYEKNARNQI GLWNLRDNGVGLNVMVSEHYQCCRKIFIQSSHNQ LNENRWLEKTLKRAEKRRSELSFMIQVKILHTTKSPAV Human APOBEC3G D316R D317R: MKPHFRNTVERMYRDTFSYNFYNRPILSRRNTVWLCYEVKTKGPSRPPLDAKIFRGQVYSELKYHPEM RFFHWFSKWRKLHRDQEYEVTWYISWSPCTKCTRDMATFLAEDPKVTLTIFVARLYYFWDPDYQEALR SLCQKRDGPRATMKFNYDEFQHCWSKFVYSQRELFEPWNNLPKYYILLHFMLGEILRHSMDPPTFTFN FNNEPWVRGRHETYLCYEVERMHNDTWVLLNQRRGFLCNQAPHKHGFLEGRHAELCFLDVIPFWKLDL DQDYRVTCFTSWSPCFSCAQEMAKFISKKHVSLCIFTARIYRRQGRCQEGLRTLAEAGAKISFTYSEF KHCWDTFVDHQGCPFQPWDGLDEHSQDLSGRLRAILQNQEN Human APOBEC3G chain A: MDPPTFTFNFNNEPWWGRHETYLCYEVERMHNDTWVLLNQRRGFLCNQAPHKHGFLEGRHAELCFLDV IPFWKLDLDQDYRVTCFTSWSPCFSCAQEMAKFISKNKHVSLCIFTARIYDDQGRCQEGLRTLAEAGA KISFTYSEFKHCWDTFVDHQGCPFQPWDGLDEHSQDLSGRLRAILQ Human APOBEC3G chain A D120R D121R: MDPPTFTFNFNNEPWVRGRHETYLCYEVERMHNDTWVLLNQRRGFLCNQAPHKHGFLEGRHAELCFLD VIPFWKLDLDQDYRVTCFTSWSPCFSCAQEMAKFISKNKHVSLCIFTARIYRRQGRCQEGLRTLAEAG AKISFMTYSEFKHCWDTFVDHQGCPFQPWDGLDEHSQDLSGRLRAILQ hAPOBEC-4 (Homo sapiens): MEPIYEEYLANHGTIVKPYYWLSFSLDCSNCPYHIRTGEEARVSLTEFCQIFGFPYGTTFPQTKHLTF YELKTSSGSLVQKGHASSCTGNYIHPESMLFEMNGYLDSAIYNNDSIRHIILYSNNSPCNEANHCCIS KMYNFLITYPGITLSIYFSQLYHTEMDFPASAWNREALRSLASLWPRVVLSPISGGIWHSVLHSFISG VSGSHVFQPILTGRALADRHNAYEINAITGVKPYFTDVLLQTKRNPNTKAQEALESYPLNNAFPGQFF QMPSGQLQPNLPPDLRAPVVFVLVPLRDLPPMHMGQNPNKPRNIVRHLNMPQMSFQETKDLGRLPTGR SVEIVEITEQFASSKEADEKKKKKGKK mAPOBEC-4 (Mus musculus): MDSLLMKQKKFLYHFKNVRWAKGRHETYLCYVVKRRDSATSCSLDFGHLRNKSGCHVELLFLRYISDW DLDPGRCYRVTWFTSWSPCYDCARHVAEFLRWNPNLSLRIFTARLYFCEDRKAEPEGLRRLHRAGVQI GIMTFKDYFYCWNTFVENRERTFKAWEGLHENSVRLTRQLRRILLPLYEVDDLRDAFRMLGF rAPOBEC-4 (Rattus norvegicus): MEPLYEEYLTHSGTIVKPYYWLSVSLNCTNCPYHIRTGEEARVPYTEFHQTFGFPWSTYPQTKHLTFY ELRSSSGNLIQKGLASNCTGSHTHPESMLFERDGYLDSLIFHDSNIRHIILYSNNSPCDEANHCCISK MYNFLMNYPEVTLSVFFSQLYHTENQFPTSAWNREALRGLASLWPQVTLSAISGGIWQSILETFVSGI SEGLTAVRPFTAGRTLTDRYNAYEINCITEVKPYFTDALHSWQKENQDQKVWAASENQPLHNTTPAQW QPDMSQDCRTPAVFMLVPYRDLPPIHVNPSPQKPRTVVRHLNTLQLSASKVKALRKSPSGRPVKKEEA RKGSTRSQEANETNKSKWKKQTLFIKSNICHLLEREQKKIGILSSWSV mfAPOBEC-4 (Macaca fascicularis): MEPTYEEYLANHGTIVKPYYWLSFSLDCSNCPYHIRTGEEARVSLTEFCQIFGFPYGTTYPQTKHLTF YELKTSSGSLVQKGHASSCTGNYIHPESMLFEMNGYLDSAIYNNDSIRHIILYCNNSPCNEANHCCIS KVYNFLITYPGITLSIYFSQLYHTEMDFPASAWNREALRSLASLWPRVVLSPISGGIWHSVLHSFVSG VSGSHVFQPILTGRALTDRYNAYEINAITGVKPFFTDVLLHTKRNPNTKAQMALESYPLNNAFPGQSF QMTSGIPPDLRAPVVFVLLPLRDLPPMHMGQDPNKPRNIIRHLNMPQMSFQETKDLERLPTRRSVETV EITERFASSKQAEEKTKKKKGKK pmCDA-1 (Petromyzon marinus): MAGYECVRVSEKLDFDTFEFQFENLHYATERHRTYVIFDVKPQSAGGRSRRLWGYIINNPNVCHAELI LMSMIDRHLESNPGVYAMTWYMSWSPCANCSSKLNPWLKNLLEEQGHTLTMHFSRIYDRDREGDHRGL RGLKHVSNSFRMGVVGRAEVKECLAEYVEASRRTLTWLDTTESMAAKMRRKLFCILVRCAGMRESGIP LHLFTLQTPLLSGRVVWWRV pmCDA-2 (Petromyzon marinus): MELREVVDCALASCVRHEPLSRVAFLRCFAAPSQKPRGTVILFYVEGAGRGVTGGHAVNYNKQGTSIH AEVLLLSAVRAALLRRRRCEDGEEATRGCTLHCYSTYSPCRDCVEYIQEFGASTGVRVVIHCCRLYEL DVNRRRSEAEGVLRSLSRLGRDFRLMGPRDAIALLLGGRLANTADGESGASGNAWVTETNVVEPLVDM TGFGDEDLHAQVQRNKQIREAYANYASAVSLMLGELHVDPDKFPFLAEFLAQTSVEPSGTPRETRGRP RGASSRGPEIGRQRPADFERALGAYGLFLHPRIVSREADREEIKRDLIVVMRKHNYQGP pmCDA-5 (Petromyzon marinus): MAGDENVRVSEKLDFDTFEFQFENLHYATERHRTYVIFDVKPQSAGGRSRRLWGYIINNPNVCHAELI LMSMIDRHLESNPGVYAMTWYMSWSPCANCSSKLNPWLKNLLEEQGHTLMMHFSRIYDRDREGDHRGL RGLKHVSNSFRMGVVGRAEVKECLAEYVEASRRTLTWLDTTESMAAKMRRKLFCILVRCAGMRESGMP LHLFT yCD (Saccharomyces cerevisiae): MVTGGMASKWDQKGMDIAYEEAALGYKEGGVPIGGCLINNKDGSVLGRGHNMRFQKGSATLHGEISTL ENCGRLEGKVYKDTTLYTTLSPCDMCTGAIIMYGIPRCVVGENVNFKSKGEKYLQTRGHEVVVVDDER CKKIMKQFIDERPQDWFEDIGE rAPOBEC-1 (delta 177-186): MSSETGPVAVDPTLRRRIEPHEFEVFFDPRELRKETCLLYEINWGGRHSIWRHTSQNTNKHVEVNFIE KFTTERYFCPNTRCSITWFLSWSPCGECSRAITEFLSRYPHVTLFIYIARLYHHADPRNRQGLRDLIS SGVTIQIMTEQESGYCWRNFVNYSPSNEAHWPRYPHLWVRGLPPCLNILRRKQPQLTFFTIALQSCHY QRLPPHILWATGLK rAPOBEC-1 (delta 202-213): MSSETGPVAVDPTLRRRIEPHEFEVFFDPRELRKETCLLYEINWGGRHSIWRHTSQNTNKHVEVNFIE KFTTERYFCPNTRCSITWFLSWSPCGECSRAITEFLSRYPHVTLFIYIARLYHHADPRNRQGLRDLIS SGVTIQIMTEQESGYCWRNFVNYSPSNEAHWPRYPHLWVRLYVLELYCIILGLPPCLNILRRKQPQHY QRLPPHILWATGLK Mouse APOBEC-3: MGPFCLGCSHRKCYSPIRNLISQETFKFHFKNLGYAKGRKDTFLCYEVTRKDCDSPVSLHHG VFKNKDNIHAEICFLYWFHDKVLKVLSPREEFKITWYMSWSPCFECAEQIVRFLATHHNLSL DIFSSRLYNVQDPETQQNLCRLVQEGAQVAAMDLYEFKKCWKKFVDNGGRRFRPWKRLLTNF RYQDSKLQEILRPCYIPVPSSSSSTLSNICLIKGLPETRFCVEGRRMDPLSEEEFYSQFYNQ RVKHLCYYHRMKPYLCYQLEQFNGQAPLKGCLLSEKGKQHAEILFLDKIRSMELSQVTITCY LTWSPCPNCAWQLAAFKRDRPDLILHIYTSRLYFHWKRPFQKGLCSLWQSGILVDVMDLPQF TDCWTNFVNPKRPFWPWKGLEIISRRTQRRLRRIKESWGLQDLVNDFGNLQLGPPMS (italic: nucleic acid editing domain)

[0565] Some aspects of the present disclosure are based on the recognition that modulating the deaminase domain catalytic activity of any of the fusion proteins described herein, for example by making point mutations in the deaminase domain, affect the processivity of the fusion proteins (e.g., base editors). For example, mutations that reduce, but do not eliminate, the catalytic activity of a deaminase domain within a base editing fusion protein can make it less likely that the deaminase domain will catalyze the deamination of a residue adjacent to a target residue, thereby narrowing the deamination window. The ability to narrow the deamination window can prevent unwanted deamination of residues adjacent to specific target residues, which can decrease or prevent off-target effects.

[0566] For example, in some embodiments, an APOBEC deaminase incorporated into a base editor can comprise one or more mutations selected from the group consisting of H121X, H122X, R126X, R126X, R118X, W90X, W90X, and R132X of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase, wherein X is any amino acid. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise one or more mutations selected from the group consisting of H121R, H122R, R126A, R126E, R118A, W90A, W90Y, and R132E of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase.

[0567] In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise one or more mutations selected from the group consisting of D316X, D317X, R320X, R320X, R313X, W285X, W285X, R326X of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase, wherein X is any amino acid. In some embodiments, any of the fusion proteins provided herein comprise an APOBEC deaminase comprising one or more mutations selected from the group consisting of D316R, D317R, R320A, R320E, R313A, W285A, W285Y, R326E of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase.

[0568] In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise a H121R and a H122R mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R126A mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R126E mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R118A mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W90A mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W90Y mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R132E mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W90Y and a R126E mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R126E and a R132E mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W90Y and a R132E mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W90Y, R126E, and R132E mutation of rAPOBEC1, or one or more corresponding mutations in another APOBEC deaminase.

[0569] In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a D316R and a D317R mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, any of the fusion proteins provided herein comprise an APOBEC deaminase comprising a R320A mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R320E mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R313A mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W285A mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W285Y mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R326E mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W285Y and a R320E mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a R320E and a R326E mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W285Y and a R326E mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase. In some embodiments, an APOBEC deaminase incorporated into a base editor can comprise an APOBEC deaminase comprising a W285Y, R320E, and R326E mutation of hAPOBEC3G, or one or more corresponding mutations in another APOBEC deaminase.

[0570] A number of modified cytidine deaminases are commercially available, including, but not limited to, SaBE3, SaKKH-BE3, VQR-BE3, EQR-BE3, VRER-BE3, YE1-BE3, EE-BE3, YE2-BE3, and YEE-BE3, which are available from Addgene (plasmids 85169, 85170, 85171, 85172, 85173, 85174, 85175, 85176, 85177). In some embodiments, a deaminase incorporated into a base editor comprises all or a portion of an APOBEC1 deaminase.

[0571] Details of C to T nucleobase editing proteins are described in International PCT Application No. PCT/US2016/058344 (WO2017/070632) and Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016), the entire contents of which are hereby incorporated by reference.

[0572] The fusion proteins provided herein comprise a cytidine deaminase. In some embodiments, the cytidine deaminases provided herein are capable of deaminating cytosine or 5-methylcytosine to uracil or thymine. In some embodiments, the cytidine deaminases provided herein are capable of deaminating cytosine in DNA. The cytidine deaminase may be derived from any suitable organism. In some embodiments, the cytidine deaminase is a naturally-occurring cytidine deaminase that includes one or more mutations corresponding to any of the mutations provided herein. In some embodiments, the cytidine deaminase has specificity for 5′-NGC-3′ PAM and may include mutations as described in Examples 4 and 5 herein. In some embodiments, base editors comprising the cytidine deaminase having specificity for 5′-NGC-3′ PAM as described are provided. One of skill in the art will be able to identify the corresponding residue in any homologous protein, e.g., by sequence alignment and determination of homologous residues. Accordingly, one of skill in the art would be able to generate mutations in any naturally-occurring cytidine deaminase that corresponds to any of the mutations described herein. In some embodiments, the cytidine deaminase is from a prokaryote. In some embodiments, the cytidine deaminase is from a bacterium. In some embodiments, the cytidine deaminase is from a mammal (e.g., human).

[0573] In some embodiments, the cytidine deaminase comprises an amino acid sequence that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 99.5% identical to any one of the cytidine deaminase amino acid sequences set forth herein. It should be appreciated that cytidine deaminases provided herein may include one or more mutations (e.g., any of the mutations provided herein). The disclosure provides any deaminase domains with a certain percent identity plus any of the mutations or combinations thereof described herein. In some embodiments, the cytidine deaminase comprises an amino acid sequence that has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, or more mutations compared to a reference sequence, or any of the cytidine deaminases provided herein. In some embodiments, the cytidine deaminase comprises an amino acid sequence that has at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100, at least 110, at least 120, at least 130, at least 140, at least 150, at least 160, or at least 170 identical contiguous amino acid residues as compared to any one of the amino acid sequences known in the art or described herein.

[0574] A fusion protein of the invention comprises two or more nucleic acid editing domains. In some embodiments, the nucleic acid editing domain can catalyze a C to U base change. In some embodiments, the nucleic acid editing domain is a deaminase domain. In some embodiments, the deaminase is a cytidine deaminase or an adenosine deaminase. In some embodiments, the deaminase is an apolipoprotein B mRNA-editing complex (APOBEC) family deaminase. In some embodiments, the deaminase is an APOBEC1 deaminase. In some embodiments, the deaminase is an APOBEC2 deaminase. In some embodiments, the deaminase is an APOBEC3 deaminase. In some embodiments, the deaminase is an APOBEC3 A deaminase. In some embodiments, the deaminase is an APOBEC3B deaminase. In some embodiments, the deaminase is an APOBEC3C deaminase. In some embodiments, the deaminase is an APOBEC3D deaminase. In some embodiments, the deaminase is an APOBEC3E deaminase. In some embodiments, the deaminase is an APOBEC3F deaminase. In some embodiments, the deaminase is an APOBEC3G deaminase. In some embodiments, the deaminase is an APOBEC3H deaminase. In some embodiments, the deaminase is an APOBEC4 deaminase. In some embodiments, the deaminase is an activation-induced deaminase (AID). In some embodiments, the deaminase is a vertebrate deaminase. In some embodiments, the deaminase is an invertebrate deaminase. In some embodiments, the deaminase is a human, chimpanzee, gorilla, monkey, cow, dog, rat, or mouse deaminase. In some embodiments, the deaminase is a human deaminase. In some embodiments, the deaminase is a rat deaminase, e.g., rAPOBEC1. In some embodiments, the deaminase is a Petromyzon marinus cytidine deaminase 1 (pmCDA1). In some embodiments, the deaminase is a human APOBEC3G. In some embodiments, the deaminase is a fragment of the human APOBEC3G. In some embodiments, the deaminase is a human APOBEC3G variant comprising a D316R D317R mutation. In some embodiments, the deaminase is a fragment of the human APOBEC3G and comprises mutations corresponding to the D316R D317R mutations. In some embodiments, the nucleic acid editing domain is at least 80%, at least 85%, at least 90%, at least 92%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%), or at least 99.5% identical to the deaminase domain of any deaminase described herein.

[0575] In certain embodiments, the fusion proteins provided herein comprise one or more features that improve the base editing activity of the fusion proteins. For example, any of the fusion proteins provided herein may comprise a Cas9 domain that has reduced nuclease activity. In some embodiments, any of the fusion proteins provided herein may have a Cas9 domain that does not have nuclease activity (dCas9), or a Cas9 domain that cuts one strand of a duplexed DNA molecule, referred to as a Cas9 nickase (nCas9).

Cas9 Complexes with Guide RNAs

[0576] Some aspects of this disclosure provide complexes comprising any of the fusion proteins provided herein, and a guide RNA bound to a Cas9 domain (e.g., a dCas9, a nuclease active Cas9, or a Cas9 nickase) of fusion protein. In some embodiments, the guide nucleic acid (e.g., guide RNA) is from 15-100 nucleotides long and comprises a sequence of at least 10 contiguous nucleotides that is complementary to a target sequence. In some embodiments, the guide RNA is 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 nucleotides long. In some embodiments, the guide RNA comprises a sequence of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 contiguous nucleotides that is complementary to a target sequence. In some embodiments, the target sequence is a DNA sequence. In some embodiments, the target sequence is a sequence in the genome of a bacteria, yeast, fungi, insect, plant, or animal. In some embodiments, the target sequence is a sequence in the genome of a human. In some embodiments, the 3′ end of the target sequence is immediately adjacent to a canonical PAM sequence (NGG). In some embodiments, the 3′ end of the target sequence is immediately adjacent to a non-canonical PAM sequence (e.g., a sequence listed in Table 1 or 5′-NAA-3′). In some embodiments, the guide nucleic acid (e.g., guide RNA) is complementary to a sequence in a gene of interest (e.g., a gene associated with a disease or disorder).

[0577] Some aspects of this disclosure provide methods of using the fusion proteins, or complexes provided herein. For example, some aspects of this disclosure provide methods comprising contacting a DNA molecule with any of the fusion proteins provided herein, and with at least one guide RNA, wherein the guide RNA is about 15-100 nucleotides long and comprises a sequence of at least 10 contiguous nucleotides that is complementary to a target sequence. In some embodiments, the 3′ end of the target sequence is immediately adjacent to an AGC, GAG, TTT, GTG, or CAA sequence. In some embodiments, the 3′ end of the target sequence is immediately adjacent to an NGA, NGCG, NGN, NNGRRT, NNNRRT, NGCG, NGCN, NGTN, NGTN, NGTN, or 5′ (TTTV) sequence.

[0578] It will be understood that the numbering of the specific positions or residues in the respective sequences depends on the particular protein and numbering scheme used. Numbering might be different, e.g., in precursors of a mature protein and the mature protein itself, and differences in sequences from species to species may affect numbering. One of skill in the art will be able to identify the respective residue in any homologous protein and in the respective encoding nucleic acid by methods well known in the art, e.g., by sequence alignment and determination of homologous residues.

[0579] It will be apparent to those of skill in the art that in order to target any of the fusion proteins disclosed herein, to a target site, e.g., a site comprising a mutation to be edited, it is typically necessary to co-express the fusion protein together with a guide RNA. As explained in more detail elsewhere herein, a guide RNA typically comprises a tracrRNA framework allowing for Cas9 binding, and a guide sequence, which confers sequence specificity to the Cas9:nucleic acid editing enzyme/domain fusion protein. Alternatively, the guide RNA and tracrRNA may be provided separately, as two nucleic acid molecules. In some embodiments, the guide RNA comprises a structure, wherein the guide sequence comprises a sequence that is complementary to the target sequence. The guide sequence is typically 20 nucleotides long. The sequences of suitable guide RNAs for targeting Cas9:nucleic acid editing enzyme/domain fusion proteins to specific genomic target sites will be apparent to those of skill in the art based on the instant disclosure. Such suitable guide RNA sequences typically comprise guide sequences that are complementary to a nucleic sequence within 50 nucleotides upstream or downstream of the target nucleotide to be edited. Some exemplary guide RNA sequences suitable for targeting any of the provided fusion proteins to specific target sequences are provided herein.

Additional Domains

[0580] A base editor described herein can include any domain which helps to facilitate the nucleobase editing, modification or altering of a nucleobase of a polynucleotide. In some embodiments, a base editor comprises a polynucleotide programmable nucleotide binding domain (e.g., Cas9), a nucleobase editing domain (e.g., deaminase domain), and one or more additional domains. In some cases, the additional domain can facilitate enzymatic or catalytic functions of the base editor, binding functions of the base editor, or be inhibitors of cellular machinery (e.g., enzymes) that could interfere with the desired base editing result.

[0581] In some embodiments, a base editor can comprise a uracil glycosylase inhibitor (UGI) domain. A UGI domain can for example improve the efficiency of base editors comprising a cytidine deaminase domain by inhibiting the conversion of a U formed by deamination of a C back to the C nucleobase. In some cases, cellular DNA repair response to the presence of U:G heteroduplex DNA can be responsible for a decrease in nucleobase editing efficiency in cells. In such cases, uracil DNA glycosylase (UDG) can catalyze removal of U from DNA in cells, which can initiate base excision repair (BER), mostly resulting in reversion of the U:G pair to a C:G pair. In such cases, BER can be inhibited in base editors comprising one or more domains that bind the single strand, block the edited base, inhibit UGI, inhibit BER, protect the edited base, and/or promote repairing of the non-edited strand. Thus, this disclosure contemplates a base editor fusion protein comprising a UGI domain.

[0582] In some embodiments, a base editor comprises as a domain all or a portion of a double-strand break (DSB) binding protein. For example, a DSB binding protein can include a Gam protein of bacteriophage Mu that can bind to the ends of DSBs and can protect them from degradation. See Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017), the entire content of which is hereby incorporated by reference.

[0583] In some embodiments, a base editor can comprise as a domain all or a portion of a nucleic acid polymerase (NAP). For example, a base editor can comprise all or a portion of a eukaryotic NAP. In some embodiments, a NAP or portion thereof incorporated into a base editor is a DNA polymerase. In some embodiments, a NAP or portion thereof incorporated into a base editor has translesion polymerase activity. In some cases, a NAP or portion thereof incorporated into a base editor is a translesion DNA polymerase. In some embodiments, a NAP or portion thereof incorporated into a base editor is a Rev7, Rev1 complex, polymerase iota, polymerase kappa, or polymerase eta. In some embodiments, a NAP or portion thereof incorporated into a base editor is a eukaryotic polymerase alpha, beta, gamma, delta, epsilon, gamma, eta, iota, kappa, lambda, mu, or nu component. In some embodiments, a NAP or portion thereof incorporated into a base editor comprises an amino acid sequence that is at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 99.5% identical to a nucleic acid polymerase (e.g., a translesion DNA polymerase).

Base Editor System

[0584] The base editor system provided herein comprises the steps of: (a) contacting a target nucleotide sequence of a polynucleotide (e.g., a double-stranded DNA or RNA, a single-stranded DNA or RNA) of a subject with a base editor system comprising an adenosine deaminase domain or a cytidine deaminase domain, wherein the aforementioned domains are fused to a polynucleotide binding domain, thereby forming a nucleobase editor capable of inducing changes at one or more bases within a nucleic acid molecule as described herein and at least one guide polynucleic acid (e.g., gRNA), wherein the target nucleotide sequence comprises a targeted nucleobase pair; (b) inducing strand separation of the target region; (c) converting a first nucleobase of the target nucleobase pair in a single strand of the target region to a second nucleobase; and (d) cutting no more than one strand of the target region, where a third nucleobase complementary to the first nucleobase base is replaced by a fourth nucleobase complementary to the second nucleobase. It should be appreciated that in some embodiments, step (b) is omitted. In some embodiments, the targeted nucleobase pair is a plurality of nucleobase pairs in one or more genes. In some embodiments, the base editor system provided herein is capable of multiplex editing of a plurality of nucleobase pairs in one or more genes. In some embodiments, the plurality of nucleobase pairs is located in the same gene. In some embodiments, the plurality of nucleobase pairs is located in one or more genes, wherein at least one gene is located in a different locus.

[0585] In some embodiments, the cut single strand (nicked strand) is hybridized to the guide nucleic acid. In some embodiments, the cut single strand is opposite to the strand comprising the first nucleobase. In some embodiments, the base editor comprises a Cas9 domain. In some embodiments, the first base is adenine, and the second base is not a G, C, A, or T. In some embodiments, the second base is inosine.

[0586] Base editing system as provided herein provides a new approach to genome editing that uses a fusion protein containing a catalytically defective Streptococcus pyogenes Cas9, a cytidine deaminase, and an inhibitor of base excision repair to induce programmable, single nucleotide (C.fwdarw.T or A.fwdarw.G) changes in DNA without generating double-strand DNA breaks, without requiring a donor DNA template, and without inducing an excess of stochastic insertions and deletions.

[0587] Provided herein are systems, compositions, and methods for editing a nucleobase using a base editor system. In some embodiments, the base editor system comprises a base editor (BE) comprising a polynucleotide programmable nucleotide binding domain and a nucleobase editing domain (e.g., deaminase domain) for editing the nucleobase; and a guide polynucleotide (e.g., guide RNA) in conjunction with the polynucleotide programmable nucleotide binding domain. In some embodiments, the base editor system comprises a base editor (BE) comprising a polynucleotide programmable nucleotide binding domain and a nucleobase editing domain (e.g., deaminase domain) for editing the nucleobase, and a guide polynucleotide (e.g., guide RNA) in conjunction with the polynucleotide programmable nucleotide binding domain. In some embodiments, the polynucleotide programmable nucleotide binding domain is a polynucleotide programmable DNA binding domain. In some embodiments, the polynucleotide programmable nucleotide binding domain is a polynucleotide programmable RNA binding domain. In some cases, a deaminase domain can be a cytosine deaminase or a cytidine deaminase, an adenine deaminase or an adenosine deaminase. In some embodiments, the terms “cytosine deaminase” and “cytidine deaminase” can be used interchangeably. In some embodiments, the terms “adenine deaminase” and “adenosine deaminase” can be used interchangeably. In some cases, a deaminase domain can be a cytosine deaminase or a cytidine deaminase. In some cases, a deaminase domain can be an adenine deaminase or an adenosine deaminase. Details of nucleobase editing proteins are described in International PCT Application Nos. PCT/2017/045381 (WO2018/027078) and PCT/US2016/058344 (WO2017/070632), each of which is incorporated herein by reference for its entirety. Also see Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N. M., et al., “Programmable base editing of A⋅T to G⋅C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); and Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017), the entire contents of which are hereby incorporated by reference.

[0588] In some embodiments, a single guide polynucleotide may be utilized to target a deaminase to a target nucleic acid sequence. In some embodiments, a single pair of guide polynucleotides may be utilized to target different deaminases to a target nucleic acid sequence.

[0589] The nucleobase components and the polynucleotide programmable nucleotide binding component of a base editor system may be associated with each other covalently or non-covalently. For example, in some embodiments, the deaminase domain can be targeted to a target nucleotide sequence by a polynucleotide programmable nucleotide binding domain. In some embodiments, a polynucleotide programmable nucleotide binding domain can be fused or linked to a deaminase domain. In some embodiments, a polynucleotide programmable nucleotide binding domain can target a deaminase domain to a target nucleotide sequence by non-covalently interacting with or associating with the deaminase domain. For example, in some embodiments, the nucleobase editing component, e.g., the deaminase component can comprise an additional heterologous portion or domain that is capable of interacting with, associating with, or capable of forming a complex with an additional heterologous portion or domain that is part of a polynucleotide programmable nucleotide binding domain. In some embodiments, the additional heterologous portion may be capable of binding to, interacting with, associating with, or forming a complex with a polypeptide. In some embodiments, the additional heterologous portion may be capable of binding to, interacting with, associating with, or forming a complex with a polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a guide polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a polypeptide linker. In some embodiments, the additional heterologous portion may be capable of binding to a polynucleotide linker. The additional heterologous portion may be a protein domain. In some embodiments, the additional heterologous portion may be a K Homology (KH) domain, a MS2 coat protein domain, a PP7 coat protein domain, a SfMu Com coat protein domain, a steril alpha motif, a telomerase Ku binding motif and Ku protein, a telomerase Sm7 binding motif and Sm7 protein, or a RNA recognition motif.

[0590] A base editor system may further comprise a guide polynucleotide component. It should be appreciated that components of the base editor system may be associated with each other via covalent bonds, noncovalent interactions, or any combination of associations and interactions thereof. In some embodiments, a deaminase domain can be targeted to a target nucleotide sequence by a guide polynucleotide. For example, in some embodiments, the nucleobase editing component of the base editor system, e.g., the deaminase component, can comprise an additional heterologous portion or domain (e.g., polynucleotide binding domain such as an RNA or DNA binding protein) that is capable of interacting with, associating with, or capable of forming a complex with a portion or segment (e.g., a polynucleotide motif) of a guide polynucleotide. In some embodiments, the additional heterologous portion or domain (e.g., polynucleotide binding domain such as an RNA or DNA binding protein) can be fused or linked to the deaminase domain. In some embodiments, the additional heterologous portion may be capable of binding to, interacting with, associating with, or forming a complex with a polypeptide. In some embodiments, the additional heterologous portion may be capable of binding to, interacting with, associating with, or forming a complex with a polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a guide polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a polypeptide linker. In some embodiments, the additional heterologous portion may be capable of binding to a polynucleotide linker. The additional heterologous portion may be a protein domain. In some embodiments, the additional heterologous portion may be a K Homology (KH) domain, a MS2 coat protein domain, a PP7 coat protein domain, a SfMu Com coat protein domain, a sterile alpha motif, a telomerase Ku binding motif and Ku protein, a telomerase Sm7 binding motif and Sm7 protein, or a RNA recognition motif.

[0591] In some embodiments, a base editor system can further comprise an inhibitor of base excision repair (BER) component. It should be appreciated that components of the base editor system may be associated with each other via covalent bonds, noncovalent interactions, or any combination of associations and interactions thereof. The inhibitor of BER component may comprise a base excision repair inhibitor. In some embodiments, the inhibitor of base excision repair can be a uracil DNA glycosylase inhibitor (UGI). In some embodiments, the inhibitor of base excision repair can be an inosine base excision repair inhibitor. In some embodiments, the inhibitor of base excision repair can be targeted to the target nucleotide sequence by the polynucleotide programmable nucleotide binding domain. In some embodiments, a polynucleotide programmable nucleotide binding domain can be fused or linked to an inhibitor of base excision repair. In some embodiments, a polynucleotide programmable nucleotide binding domain can be fused or linked to a deaminase domain and an inhibitor of base excision repair. In some embodiments, a polynucleotide programmable nucleotide binding domain can target an inhibitor of base excision repair to a target nucleotide sequence by non-covalently interacting with or associating with the inhibitor of base excision repair. For example, in some embodiments, the inhibitor of base excision repair component can comprise an additional heterologous portion or domain that is capable of interacting with, associating with, or capable of forming a complex with an additional heterologous portion or domain that is part of a polynucleotide programmable nucleotide binding domain. In some embodiments, the inhibitor of base excision repair can be targeted to the target nucleotide sequence by the guide polynucleotide. For example, in some embodiments, the inhibitor of base excision repair can comprise an additional heterologous portion or domain (e.g., polynucleotide binding domain such as an RNA or DNA binding protein) that is capable of interacting with, associating with, or capable of forming a complex with a portion or segment (e.g., a polynucleotide motif) of a guide polynucleotide. In some embodiments, the additional heterologous portion or domain of the guide polynucleotide (e.g., polynucleotide binding domain such as an RNA or DNA binding protein) can be fused or linked to the inhibitor of base excision repair. In some embodiments, the additional heterologous portion may be capable of binding to, interacting with, associating with, or forming a complex with a polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a guide polynucleotide. In some embodiments, the additional heterologous portion may be capable of binding to a polypeptide linker. In some embodiments, the additional heterologous portion may be capable of binding to a polynucleotide linker. The additional heterologous portion may be a protein domain. In some embodiments, the additional heterologous portion may be a K Homology (KH) domain, a MS2 coat protein domain, a PP7 coat protein domain, a SfMu Com coat protein domain, a sterile alpha motif, a telomerase Ku binding motif and Ku protein, a telomerase Sm7 binding motif and Sm7 protein, or a RNA recognition motif.

[0592] In some embodiments, the base editor inhibits base excision repair of the edited strand. In some embodiments, the base editor protects or binds the non-edited strand. In some embodiments, the base editor comprises UGI activity. In some embodiments, the base editor comprises a catalytically inactive inosine-specific nuclease. In some embodiments, the base editor comprises nickase activity. In some embodiments, the intended edit of base pair is upstream of a PAM site. In some embodiments, the intended edit of base pair is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nucleotides upstream of the PAM site. In some embodiments, the intended edit of base-pair is downstream of a PAM site. In some embodiments, the intended edited base pair is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nucleotides downstream stream of the PAM site.

[0593] In some embodiments, the method does not require a canonical (e.g., NGG) PAM site. In some embodiments, the nucleobase editor comprises a linker or a spacer. In some embodiments, the linker or spacer is 1-25 amino acids in length. In some embodiments, the linker or spacer is 5-20 amino acids in length. In some embodiments, the linker or spacer is 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acids in length.

[0594] In some embodiments, the target region comprises a target window, wherein the target window comprises the target nucleobase pair. In some embodiments, the target window comprises 1-10 nucleotides. In some embodiments, the target window is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nucleotides in length. In some embodiments, the intended edit of base pair is within the target window. In some embodiments, the target window comprises the intended edit of base pair. In some embodiments, the method is performed using any of the base editors provided herein. In some embodiments, a target window is a deamination window.

[0595] In some embodiments, non-limiting exemplary cytidine base editors (CBE) include BE1 (APOBEC1-XTEN-dCas9), BE2 (APOBEC1-XTEN-dCas9-UGI), BE3 (APOBEC1-XTEN-dCas9 (A840H)-UGI), BE3-Gam, saBE3, saBE4-Gam, BE4, BE4-Gam, saBE4, or saB4E-Gam. BE4 extends the APOBEC1-Cas9n (D10A) linker to 32 amino acids and the Cas9n-UGI linker to 9 amino acids, and appends a second copy of UGI to the C-terminus of the construct with another 9-amino acid linker into a single base editor construct. The base editors saBE3 and saBE4 have the S. pyogenes Cas9n (D10A) replaced with the smaller S. aureus Cas9n (D10A). BE3-Gam, saBE3-Gam, BE4-Gam, and saBE4-Gam have 174 residues of Gam protein fused to the N-terminus of BE3, saBE3, BE4, and saBE4 via the 16 amino acid XTEN linker.

[0596] In some embodiments, the adenosine base editor (ABE) can deaminate adenine in DNA. In some embodiments, ABE is generated by replacing APOBEC1 component of BE3 with natural or engineered E. coli TadA, human ADAR2, mouse ADA, or human ADAT2. In some embodiments, ABE comprises evolved TadA variant. In some embodiments, the ABE is ABE 1.2 (TadA*-XTEN-nCas9-NLS). In some embodiments, TadA* comprises A106V and D108N mutations.

[0597] In some embodiments, the ABE is a second-generation ABE. In some embodiments, the ABE is ABE2.1, which comprises additional mutations D147Y and E155V in TadA* (TadA*2.1). In some embodiments, the ABE is ABE2.2, ABE2.1 fused to catalytically inactivated version of human alkyl adenine DNA glycosylase (AAG with E125Q mutation). In some embodiments, the ABE is ABE2.3, ABE2.1 fused to catalytically inactivated version of E. coli Endo V (inactivated with D35A mutation). In some embodiments, the ABE is ABE2.6 which has a linker twice as long (32 amino acids, (SGGS).sub.2-XTEN-(SGGS).sub.2) as the linker in ABE2.1. In some embodiments, the ABE is ABE2.7, which is ABE2.1 tethered with an additional wild-type TadA monomer. In some embodiments, the ABE is ABE2.8, which is ABE2.1 tethered with an additional TadA*2.1 monomer. In some embodiments, the ABE is ABE2.9, which is a direct fusion of evolved TadA (TadA*2.1) to the N-terminus of ABE2.1. In some embodiments, the ABE is ABE2.10, which is a direct fusion of wild type TadA to the N-terminus of ABE2.1. In some embodiments, the ABE is ABE2.11, which is ABE2.9 with an inactivating E59A mutation at the N-terminus of TadA* monomer. In some embodiments, the ABE is ABE2.12, which is ABE2.9 with an inactivating E59A mutation in the internal TadA* monomer.

[0598] In some embodiments, the ABE is a third generation ABE. In some embodiments, the ABE is ABE3.1, which is ABE2.3 with three additional TadA mutations (L84F, H123Y, and I157F).

[0599] In some embodiments, the ABE is a fourth generation ABE. In some embodiments, the ABE is ABE4.3, which is ABE3.1 with an additional TadA mutation A142N (TadA*4.3).

[0600] In some embodiments, the ABE is a fifth generation ABE. In some embodiments, the ABE is ABE5.1, which is generated by importing a consensus set of mutations from surviving clones (H36L, R51L, S146C, and K157N) into ABE3.1. In some embodiments, the ABE is ABE5.3, which has a heterodimeric construct containing wild-type E. coli TadA fused to an internal evolved TadA*. In some embodiments, the ABE is ABE5.2, ABE5.4, ABE5.5, ABE5.6, ABE5.7, ABE5.8, ABE5.9, ABE5.10, ABE5.11, ABE5.12, ABE5.13, or ABE5.14, as shown in below Table 6. In some embodiments, the ABE is a sixth generation ABE. In some embodiments, the ABE is ABE6.1, ABE6.2, ABE6.3, ABE6.4, ABE6.5, or ABE6.6, as shown in below Table 6. In some embodiments, the ABE is a seventh generation ABE. In some embodiments, the ABE is ABE7.1, ABE7.2, ABE7.3, ABE7.4, ABE7.5, ABE7.6, ABE7.7, ABE7.8, ABE 7.9, or ABE7.10, as shown in Table 6 below.

TABLE-US-00078 TABLE 6 Genotypes of ABEs 23 26 36 37 48 49 51 72 84 87 106 108 123 125 142 146 147 152 155 156 157 161 ABE0.1 W R H N P R N L S A D H G A S D R E I K K ABE0.2 W R H N P R N L S A D H G A S D R E I K K ABE1.1 W R H N P R N L S A N H G A S D R E I K K ABE1.2 W R H N P R N L S V N H G A S D R E I K K ABE2.1 W R H N P R N L S V N H G A S D R E I K K ABE2.2 W R H N P R N L S V N H G A S D R E I K K ABE2.3 W R H N P R N L S V N H G A S D R E I K K ABE2.4 W R H N P R N L S V N H G A S D R E I K K ABE2.5 W R H N P R N L S V N H G A S D R E I K K ABE2.6 W R H N P R N L S V N H G A S D R E I K K ABE2.7 W R H N P R N L S V N H G A S D R E I K K ABE2.8 W R H N P R N L S V N H G A S D R E I K K ABE2.9 W R H N P R N L S V N H G A S D R E I K K ABE2.10 W R H N P R N L S V N H G A S D R E I K K ABE2.11 W R H N P R N L S V N H G A S D R E I K K ABE2.12 W R H N P R N L S V N H G A S D R E I K K ABE3.1 W R H N P R N F S V N Y G A S D R E F K K ABE3.2 W R H N P R N F S V N Y G A S D R E F K K ABE3.3 W R H N P R N F S V N Y G A S D R E F K K ABE3.4 W R H N P R N F S V N Y G A S D R E F K K ABE3.5 W R H N P R N F S V N Y G A S D R E F K K ABE3.6 W R H N P R N F S V N Y G A S D R E F K K ABE3.7 W R H N P R N F S V N Y G A S D R E F K K ABE3.8 W R H N P R N F S V N Y G A S D R E F K K ABE4.1 W R H N P R N L S V N H G N S D R E I K K ABE4.2 W G H N P R N L S V N H G N S D R E I K K ABE4.3 W R H N P R N F S V N Y G N S D R E F K K ABE5.1 W R L N P L N F S V N Y G A C D R E F N T ABE5.2 W R H S P R N I S V N Y G A S D R E F K K ABE5.3 W R L N P L N F S V N Y G A C D R E F N T ABE5.4 W R H S P R N F S V N Y G A S D R E F K K ABE5.5 W R L N P L N F S V N Y G A C D R E F N K ABE5.6 W R L N P L N F S V N Y G A C D R E F N K ABE5.7 W R L N P L N F S V N Y G A C D R E F N K ABE5.8 W R L N P L N F S V N Y G A C D R E F N K ABE5.9 W R L N P L N F S V N Y G A C D R E F N K ABE5.10 W R L N P L N F S V N Y G A C D R E F N K ABE5.11 W R L N P L N F S V N Y G A C D R E F N K ABE5.12 W R L N P L N F S V N Y G A C D R E F N K ABE5.13 W R H N P L D F S V N Y A A S D R E F K K ABE5.14 W R H N S L N F C V N Y G A S D R E F K K ABE6.1 W R H N S L N F S V N Y G N S D R E F K K ABE6.2 W R H N P V L N F S V N Y G N S Y R V F N K ABE6.3 W R L N T L N F S V N Y G A C Y R V F N K ABE6.4 W R L N S L N F S V N Y G N C Y R V F N K ABE6.5 W R L N S V L N F S V N Y G A C Y R V F N K ABE6.6 W R L N T V L N F S V N Y G N C Y R V F N K ABE7.1 W R L N T L N F S V N Y G A C Y R V F N K ABE7.2 W R L N A L N F S V N Y G N C Y R V F N K ABE7.3 L R L N A L N F S V N Y G A C Y R V F N K ABE7.4 R R L N A L N F S V N Y G A C Y R V F N K ABE7.5 W R L N A L N F S V N Y G A C Y H V F N K ABE7.6 W R L N A L N I S V N Y G A C Y P V F N K ABE7.7 L R L N A L N F S V N Y G A C Y P V F N K ABE7.8 L R L N A L N F S V N Y G N C Y R V F N K ABE7.9 L R L N A L N F S V N Y G N C Y P V F N K ABE7.10 R R L N A L N F S V N Y G A C Y P V F N K

[0601] In some embodiments, the adenosine base editor is an eighth generation ABE (ABE8). In some embodiments, the ABE8 contains a TadA*8 variant. In some embodiments, the ABE8 is a monomeric construct containing a TadA*8 variant. In some embodiments, the ABE8 is ABE8.1, which has a monomeric construct containing TadA*7.10 with a Y147T mutation (TadA*8.1). In some embodiments, the ABE8 is ABE8.2, which has a monomeric construct containing TadA*7.10 with a Y147R mutation (TadA*8.2). In some embodiments, the ABE8 is ABE8.3, which has a monomeric construct containing TadA*7.10 with a Q154S mutation (TadA*8.2). In some embodiments, the ABE8 is ABE8.4, which has a monomeric construct containing TadA*7.10 with a Y123H mutation (TadA*8.3). In some embodiments, the ABE8 is ABE8.5, which has a monomeric construct containing TadA*7.10 with a V82S mutation (TadA*8.4). In some embodiments, the ABE8 is ABE8.6, which has a monomeric construct containing TadA*7.10 with a T166R mutation (TadA*8.6). In some embodiments, the ABE8 is ABE8.7, which has a monomeric construct containing TadA*7.10 with a Q154R mutation (TadA*8.7). In some embodiments, the ABE8 is ABE8.8, which has a monomeric construct containing TadA*7.10 with Y147R, Q154R, and Y123H mutations (TadA*8.8). In some embodiments, the ABE8 is ABE8.9, which has a monomeric construct containing TadA*7.10 with Y147R, Q154R and I76Y mutations (TadA*8.9). In some embodiments, the ABE8 is ABE8.10, which has a monomeric construct containing TadA*7.10 with Y147R, Q154R, and T166R mutations (TadA*8.10). In some embodiments, the ABE8 is ABE8.11, which has a monomeric construct containing TadA*7.10 with Y147T and Q154R mutations (TadA*8.11). In some embodiments, the ABE8 is ABE8.12, which has a monomeric construct containing TadA*7.10 with Y147T and Q154S mutations (TadA*8.12). In some embodiments, the ABE8 is ABE8.13, which has a monomeric construct containing TadA*7.10 with Y123H, Y147R, and I76Y mutations (TadA*8.13).

[0602] In some embodiments, the ABE8 has a heterodimeric construct containing wild-type E. coli TadA fused to a TadA*8 variant. In some embodiments, the ABE8 is ABE8.14, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with a Y147T mutation (TadA*8.14). In some embodiments, the ABE8 is ABE8.15, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with a Y147R mutation (TadA*8.15). In some embodiments, the ABE8 is ABE8.16, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with a Q154S mutation (TadA*8.16). In some embodiments, the ABE8 is ABE8.17, which has a heterodimeric construct containing wild-type E. coli TadA fused to Tad*7.10 with a Y123H mutation (TadA*8.17). In some embodiments, the ABE8 is ABE8.18, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with a V82S mutation (TadA*8.18). In some embodiments, the ABE8 is ABE8.19, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with a T166R mutation (TadA*8.19). In some embodiments, the ABE8 is ABE8.20, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with a Q154R mutation (TadA*8.20). In some embodiments, the ABE8 is ABE8.21, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with Y147R, Q154R, and Y123H mutations (TadA*8.21). In some embodiments, the ABE8 is ABE8.22, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with Y147R, Q154R and I76Y mutations (TadA*8.22). In some embodiments, the ABE8 is ABE8.23, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with Y147R, Q154R, and T166R mutations (TadA*8.23). In some embodiments, the ABE8 is ABE8.24, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with Y147T and Q154R mutations (TadA*8.24). In some embodiments, the ABE8 is ABE8.25, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with Y147T and Q154S mutations (TadA*8.25). In some embodiments, the ABE8 is ABE8.26, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with Y123H, Y147R, and I76Y mutations (TadA*8.26).

[0603] In some embodiments the ABE is ABE8.1, ABE8.2, ABE8.3, ABE8.4, ABE8.5, ABE8.6, ABE8.6, ABE8.7, ABE8.8, ABE8.9, ABE8.10, ABE8.11, ABE8.12, ABE8.13, ABE8.14, ABE8.15, ABE8.16, ABE8.17, ABE8.18, ABE8.19, ABE8.20, ABE8.21, ABE8.22, ABE8.23, ABE8.24, ABE8.25, or ABE8.26, as shown in Table 7A below.

TABLE-US-00079 TABLE 7A ABE8 base editors ABE8 Base Adenosine Editor Deaminase Adenosine Deaminase Description ABE8.1 TadA*8.1 Monomer_TadA*7.10 + Y147T ABE8.2 TadA*8.2 Monomer_TadA*7.10 + Y147R ABE8.3 TadA*8.3 Monomer_TadA*7.10 + Q154S ABE8.4 TadA*8.4 Monomer_TadA*7.10 + Y123H ABE8.5 TadA*8.5 Monomer_TadA*7.10 + V82S ABE8.6 TadA*8.6 Monomer_TadA*7.10 + T166R ABE8.7 TadA*8.7 Monomer_TadA*7.10 + Q154R ABE8.8 TadA*8.8 Monomer_TadA*7.10 + Y147R_Q154R_Y123H ABE8.9 TadA*8.9 Monomer_TadA*7.10 + Y147R_Q154R_I76Y ABE8.10 TadA*8.10 Monomer_TadA*7.10 + Y147R_Q154R_T166R ABE8.11 TadA*8.11 Monomer_TadA*7.10 + Y147T_Q154R ABE8.12 TadA*8.12 Monomer_TadA*7.10 + Y147T_Q154S ABE8.13 TadA*8.13 Monomer_TadA*7.10 + H123H_Y147R_Q154R_I76Y ABE8.14 TadA*8.14 Heterodimer_(WT) + (TadA*7.10 + Y147T) ABE8.15 TadA*8.15 Heterodimer_(WT) + (TadA*7.10 + Y147R) ABE8.16 TadA*8.16 Heterodimer_(WT) + (TadA*7.10 + Q154S) ABE8.17 TadA*8.17 Heterodimer_(WT) + (TadA*7.10 + Y123H) ABE8.18 TadA*8.18 Heterodimer_(WT) + (TadA*7.10 + V82S) ABE8.19 TadA*8.19 Heterodimer_(WT) + (TadA*7.10 + T166R) ABE8.20 TadA*8.20 Heterodimer_(WT) + (TadA*7.10 + Q154R) ABE8.21 TadA*8.21 Heterodimer_(WT) + (TadA*7.10 + Y147R_Q154R_Y123H) ABE8.22 TadA*8.22 Heterodimer_(WT) + (TadA*7.10 + Y147R_Q154R_I76Y) ABE8.23 TadA*8.23 Heterodimer_(WT) + (TadA*7.10 + Y147R_Q154R_T166R) ABE8.24 TadA*8.24 Heterodimer_(WT) + (TadA*7.10 + Y147T_Q154R) ABE8.25 TadA*8.25 Heterodimer_(WT) + (TadA*7.10 + Y147T_Q154S) ABE8.26 TadA*8.26 Heterodimer_(WT) + (TadA*7.10 + H123H_Y147T_Q154R_I76Y)

[0604] In some embodiments, the ABE has a genotype as shown in Table 7A-1 below:

TABLE-US-00080 TABLE 7A-1 Genotypes of ABEs 23 26 36 37 48 49 51 72 84 87 105 108 123 125 142 145 147 152 155 156 157 161 ABE7.9 L R L N A L N F S V N Y G N C Y P C F N K ABE7.10 R R L N A L N F S V N Y G A C Y P C F N K
As shown in Table 7A-2 below, genotypes of 40 ABE8s are described. Residue positions in the evolved E. coli TadA portion of ABE are indicated. Mutational changes in ABE8 are shown when distinct from ABE7.10 mutations. In some embodiments, the ABE has a genotype of one of the ABEs as shown in Table 7A-2 below.

TABLE-US-00081 TABLE 7A-2 Residue Identity in Evolved TadA 23 36 48 51 76 82 84 106 108 123 146 147 152 154 155 156 157 166 ABE7.10 R L A L I V F V N Y C Y P Q V F N T ABE8.1-m T ABE8.2-m R ABE8.3-m S ABE8.4-m H ABE8.5-m S ABE8.6-m R ABE8.7-m R ABE8.8-m H R R ABE8.9-m Y R R ABE8.10-m R R R ABE8.11-m T R ABE8.12-m T S ABE8.13-m Y H R R ABE8.14-m Y S ABE8.15-m S R ABE8.16-m S H R ABE8.17-m S R ABE8.18-m S H R ABE8.19-m S H R R ABE8.20-m Y S H R R ABE8.21-m R S ABE8.22-m S S ABE8.23-m S H ABE8.24-m S H T ABE8.1-d T ABE8.2-d R ABE8.3-d S ABE8.4-d H ABE8.5-d S ABE8.6-d R ABE8.7-d R ABE8.8-d H R R ABE8.9-d Y R R ABE8.10-d R R R ABE8.11-d T R ABE8.12-d T S ABE8.13-d Y H R R ABE8.14-d Y S ABE8.15-d S R ABE8.16-d S H R ABE8.17-d S R ABE8.18-d S H R ABE8.19-d S H R R ABE8.20-d Y S H R R ABE8.21-d R S ABE8.22-d S S ABE8.23-d S H ABE8.24-d S H T

[0605] In some embodiments, base editors (e.g., ABE8) are generated by cloning an adenosine deaminase variant (e.g., TadA*8) into a scaffold that includes a circular permutant Cas9 (e.g., CP5) and a bipartite nuclear localization sequence. In some embodiments, the base editor (e.g., ABE7.9, ABE7.10, or ABE8) is a NGC PAM CP5 variant (S. pyrogenes Cas9 or spVRQR Cas9). In some embodiments, the base editor (e.g., ABE7.9, ABE7.10, or ABE8) is a AGA PAM CP5 variant (S. pyrogenes Cas9 or spVRQR Cas9).

[0606] In some embodiments, the base editor is ABE8.1, which comprises or consists essentially of the following sequence or a fragment thereof having adenosine deaminase activity:

TABLE-US-00082 ABE8.1_Y147T_CP5_NGC PAM_monomer MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCTFFRMPRQVFNAQKKAQSSTD EIGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWDK GRDFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWDPKKYGGFMQPT VAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPK YSLFELENGRKRMLASAKFLQKGNELALPSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQH KHYLDEIIEQISEFSKRVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPRAF KYFDTTIARKEYRSTKEVLDATLIHQSITGLYETRIDLSQLGGD DKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGALLFDSGETAE ATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKKHERHPIFGNI VDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKL FIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLIALSL GLTPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSDAILLSDILRV NTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYAGYIDGGASQE EFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPF LKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFIER MTNFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKKAIVDLLFKTN RKVTVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLDNEENEDILED IVLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTIL DFLKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVK VVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQILKEHPVENT QLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKVLTRSDKNRGK SDNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQIT KHVAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLN AVVGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEGADKRTADGSEFESPKKKRKV*
In the above sequence, the plain text denotes an adenosine deaminase sequence, bold sequence indicates sequence derived from Cas9, the italics sequence denotes a linker sequence, and the underlined sequence denotes a bipartite nuclear localization sequence.

[0607] In some embodiments, the base editor is ABE8.1, which comprises or consists essentially of the following sequence or a fragment thereof having adenosine deaminase activity:

TABLE-US-00083 pNMG-B335 ABE8.1_Y147T_CP5_NGCPAM_monomer: MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIG LHDPTAHAEIMALRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIG RVVFGVRNAKTGAAGSLMDVLHYPGMNHRVEITEGILADECAALLCTFFR MPRQVFNAQKKAQSSTDSGGSSGGSSGSETPGTSESATPESSGGSSGGSE IGKATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGR DFATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWDP KKYGGFMQPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNP IDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAKFLQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSK RVILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPRAFKYFD TTIARKEYRSTKEVLDATLIHQSITGLYETRIDLSQLGGDGGSGGSGGSG GSGGSGGSGGMDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDR HSIKKNLIGALLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEM AKVDDSFFHRLEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRK KLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQ TYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGN LIALSLGLTPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLF LAAKNLSDAILLSDILRVNTEITKAPLSASMIKRYDEHHQDLTLLKALVR QQLPEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGTEELL VKLNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKI EKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQS FIERMTNFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFL SGEQKKAIVDLLFKTNRKVTVKQLKEDYFKKIECFDSVEISGVEDRFNAS LGTYHDLLKIIKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLKTYA HLFDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFAN RNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQT VKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKE LGSQILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDH IVPQSFLKDDSIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAK LITQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMN TKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLN AVVGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEGADKRTADGSEF ESPKKKRKV*
In the above sequence, the plain text denotes an adenosine deaminase sequence, bold sequence indicates sequence derived from Cas9, the italics sequence denotes a linker sequence, and the underlined sequence denotes a bipartite nuclear localization sequence.

[0608] In some embodiments, the base editor is ABE8.14, which comprises or consists essentially of the following sequence or a fragment thereof having adenosine deaminase activity:

TABLE-US-00084 pNMG-357_ABE8.14 with NGC PAM CP5 MSEVEFSHEYWMRHALTLAKRAWDEREVPVGAVLVHNNRVIGEGWNRPIG RHDPTAHAEIMALRQGGLVMQNYRLIDATLYVTLEPCVMCAGAMIHSRIG RVVFGARDAKTGAAGSLMDVLHHPGMNHRVEITEGILADECAALLSDFFR MRRQEIKAQKKAQSSTDGGSSGGSSGSETPGTSESATPESSGGSSGGSMS EVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLH DPTAHAEIMALRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRV VFGVRNAKTGAAGSLMDVLHYPGMNHRVEITEGILADECAALLCTFFRMP RQVFNAQKKAQSSTDSGGSSGGSSGSETPGTSESATPESSGGSSGGSEIG KATAKYFFYSNIMNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDF ATVRKVLSMPQVNIVKKTEVQTGGFSKESILPKRNSDKLIARKKDWDPKK YGGFMQPTVAYSVLVVAKVEKGKSKKLKSVKELLGITIMERSSFEKNPID FLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASAKFLQKGNELALPS KYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRV ILADANLDKVLSAYNKHRDKPIREQAENIIHLFTLTNLGAPRAFKYFDTT IARKEYRSTKEVLDATLIHQSITGLYETRIDLSQLGGDGGSGGSGGSGGS GGSGGSGGMDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHS IKKNLIGALLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAK VDDSFFHRLEESFLVEEDKKHERHPIFGNIVDEVAYHEKYPTIYHLRKKL VDSTDKADLRLIYLALAHMIKFRGHFLIEGDLNPDNSDVDKLFIQLVQTY NQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNGLFGNLI ALSLGLTPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLA AKNLSDAILLSDILRVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQ LPEKYKEIFFDQSKNGYAGYIDGGASQEEFYKFIKPILEKMDGTEELLVK LNREDLLRKQRTFDNGSIPHQIHLGELHAILRRQEDFYPFLKDNREKIEK ILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDKGASAQSFI ERMTNFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSG EQKKAIVDLLFKTNRKVTVKQLKEDYFKKIECFDSVEISGVEDRFNASLG TYHDLLKIIKDKDFLDNEENEDILEDIVLTLTLFEDREMIEERLKTYAHL FDDKVMKQLKRRRYTGWGRLSRKLINGIRDKQSGKTILDFLKSDGFANRN FMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPAIKKGILQTVK VVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELG SQILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIV PQSFLKDDSIDNKVLTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLI TQRKFDNLTKAERGGLSELDKAGFIKRQLVETRQITKHVAQILDSRMNTK YDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINNYHHAHDAYLNAV VGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEGADKRTADGSEFES PKKKRKV*
In the above sequence, the plain text denotes an adenosine deaminase sequence, bold sequence indicates sequence derived from Cas9, the italics sequence denotes a linker sequence, and the underlined sequence denotes a bipartite nuclear localization sequence.

[0609] In some embodiments, an ABE8 of the invention is selected from the following sequences:

TABLE-US-00085 01. monoABE8.1_bpNLS + Y147T MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCIFFRMPRQVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGTNSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 02. monoABE8.1_bpNLS + Y147R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCRFERMPRQVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 03. monoABE8.1_bpNLS + Q154S MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRSVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 04. monoABE8.1_bpNLS + Y123H MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHHP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 05. monoABE8.1_bpNLS + V82S MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYSTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 6. monoABE8.1_bpNLS + T166R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSRDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 7. monoABE8.1_bpNLS + Q154R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRRVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 08. monoABE8.1_bpNLS + Y147R_Q154R_Y123H MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHHP GMNHRVEITEGILADECAALLCRFERMPRRVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 09. monoABE8.1_bpNLS + Y147R_Q154R_I76Y MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLYDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCRFERMPRRVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 10. monoABE8.1_bpNLS + Y147R_Q154R_T166R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCRFERMPRRVFNAQKKAQSSRDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 11. monoABE8.1_bpNLS + Y147T_Q154R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCIFFRMPRRVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 12. monoABE8.1_bpNLS + Y147T_Q154S MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCIFFRMPRSVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 13. monoABE8.1_bpNLS + H123Y123H_Y147R_Q154R_I76Y MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLYDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHHP GMNHRVEITEGILADECAALLCRFERMPRRVFNAQKKAQSSIDSGGSSGGSSGSETPGISES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNIDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIEGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKERGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLIPNEKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLILLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMINFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLILTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLIFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LIRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKEDNLIKAERGGLSELDKAGFIK RQLVETRQIIKHVAQILDSRMNIKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGIALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPIVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLINLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV 14. monoABE8.1_bpNLS + V82S + Q154R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDAILYSTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRRVFNAQKKAQSSTDSGGSSGGSSGSETPGTSES ATPESSGGSSGGSDKKYSIGLAIGINSVGWAVITDEYKVPSKKFKVLGNTDRHSIKKNLIGA LLFDSGETAEATRLKRTARRRYTRRKNRICYLQEIFSNEMAKVDDSFFHRLEESFLVEEDKK HERHPIFGNIVDEVAYHEKYPTIYHLRKKLVDSTDKADLRLIYLALAHMIKFRGHFLIEGDL NPDNSDVDKLFIQLVQTYNQLFEENPINASGVDAKAILSARLSKSRRLENLIAQLPGEKKNG LFGNLIALSLGLTPNFKSNFDLAEDAKLQLSKDTYDDDLDNLLAQIGDQYADLFLAAKNLSD AILLSDILRVNTEITKAPLSASMIKRYDEHHQDLTLLKALVRQQLPEKYKEIFFDQSKNGYA GYIDGGASQEEFYKFIKPILEKMDGTEELLVKLNREDLLRKQRTFDNGSIPHQIHLGELHAI LRRQEDFYPFLKDNREKIEKILTFRIPYYVGPLARGNSRFAWMTRKSEETITPWNFEEVVDK GASAQSFIERMTNFDKNLPNEKVLPKHSLLYEYFTVYNELTKVKYVTEGMRKPAFLSGEQKK AIVDLLFKINRKVIVKQLKEDYFKKIECFDSVEISGVEDRFNASLGTYHDLLKIIKDKDFLD NEENEDILEDIVLTLTLFEDREMIEERLKTYAHLFDDKVMKQLKRRRYTGWGRLSRKLINGI RDKQSGKTILDFLKSDGFANRNFMQLIHDDSLTFKEDIQKAQVSGQGDSLHEHIANLAGSPA IKKGILQTVKVVDELVKVMGRHKPENIVIEMARENQTTQKGQKNSRERMKRIEEGIKELGSQ ILKEHPVENTQLQNEKLYLYYLQNGRDMYVDQELDINRLSDYDVDHIVPQSFLKDDSIDNKV LTRSDKNRGKSDNVPSEEVVKKMKNYWRQLLNAKLITQRKFDNLTKAERGGLSELDKAGFIK RQLVETRQITKHVAQILDSRMNTKYDENDKLIREVKVITLKSKLVSDFRKDFQFYKVREINN YHHAHDAYLNAVVGTALIKKYPKLESEFVYGDYKVYDVRKMIAKSEQEIGKATAKYFFYSNI MNFFKTEITLANGEIRKRPLIETNGETGEIVWDKGRDFATVRKVLSMPQVNIVKKTEVQTGG FSKESILPKRNSDKLIARKKDWDPKKYGGFVSPTVAYSVLVVAKVEKGKSKKLKSVKELLGI TIMERSSFEKNPIDFLEAKGYKEVKKDLIIKLPKYSLFELENGRKRMLASARELQKGNELAL PSKYVNFLYLASHYEKLKGSPEDNEQKQLFVEQHKHYLDEIIEQISEFSKRVILADANLDKV LSAYNKHRDKPIREQAENIIHLFTLTNLGAPAAFKYFDTTIDRKQYRSTKEVLDATLIHQSI TGLYETRIDLSQLGGDEGADKRTADGSEFESPKKKRKV

[0610] In some embodiments, the ABE8 is ABE8a-m, which has a monomeric construct containing TadA*7.10 with R26C, A109S, T111R, D119N, H122N, Y147D, F149Y, 11661, and D167N mutations (TadA*8a). In some embodiments, the ABE8 is ABE8b-m, which has a monomeric construct containing TadA*7.10 with V88A, A109S, T111R, D119N, H122N, F149Y, T166I, and D167N mutations (TadA*8b). In some embodiments, the ABE8 is ABE8c-m, which has a monomeric construct containing TadA*7.10 with R26C, A109S, T111R, D119N, H122N, F149Y, 11661, and D167N mutations (TadA*8c). In some embodiments, the ABE8 is ABE8d-m, which has a monomeric construct containing TadA*7.10 with V88A, T111R, D119N, and F149Y mutations (TadA*8d). In some embodiments, the ABE8 is ABE8e-m, which has a monomeric construct containing TadA*7.10 with A109S, T111R, D119N, H122N, Y147D, F149Y, T166I, and D167N mutations (TadA*8e).

[0611] In some embodiments, the ABE8 is ABE8a-d, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with R26C, A109S, T111R, D119, H122N, Y147D, F149Y, T166I, and D167N mutations (TadA*8a). In some embodiments, the ABE8 is ABE8b-d, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with V88A, A109S, T111R, D119N, H122N, F149Y, T166I, and D167N mutations (TadA*8b). In some embodiments, the ABE8 is ABE8c-d, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with R26C, A109S, T111R, D119N, H122N, F149Y, T166I, and D167N mutations (TadA*8c). In some embodiments, the ABE8 is ABE8d-d, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with V88A, T111R, D119N, and F149Y mutations (TadA*8d). In some embodiments, the ABE8 is ABE8e-d, which has a heterodimeric construct containing wild-type E. coli TadA fused to TadA*7.10 with A109S, T111R, D119N, H122N, Y147D, F149Y, T166I, and D167N mutations (TadA*8e).

[0612] In some embodiments, the ABE8 is ABE8a-7, which has a heterodimeric construct containing TadA*7.10 fused to TadA*7.10 with R26C, A109S, T111R, D119, H122N, Y147D, F149Y, T166I, and D167N mutations (TadA*8a). In some embodiments, the ABE8 is ABE8b-7, which has a heterodimeric construct containing TadA*7.10 fused to TadA*7.10 with V88A, A109S, T111R, D119N, H122N, F149Y, T166I, and D167N mutations (TadA*8b). In some embodiments, the ABE8 is ABE8c-7, which has a heterodimeric construct containing TadA*7.10 fused to TadA*7.10 with R26C, A109S, T111R, D119N, H122N, F149Y, T166I, and D167N mutations (TadA*8c). In some embodiments, the ABE8 is ABE8d-7, which has a heterodimeric construct containing TadA*7.10 fused to TadA*7.10 with V88A, T111R, D119N, and F149Y mutations (TadA*8d). In some embodiments, the ABE8 is ABE8e-7, which has a heterodimeric construct containing TadA*7.10 fused to TadA*7.10 with A109S, T111R, D119N, H122N, Y147D, F149Y, T166I, and D167N mutations (TadA*8e).

[0613] In some embodiments, the ABE is ABE8a-m, ABE8b-m, ABE8c-m, ABE8d-m, ABE8e-m, ABE8a-d, ABE8b-d, ABE8c-d, ABE8d-d, or ABE8e-d, as shown in Table 7B below. In some embodiments, the ABE is ABE8e-m or ABE8e-d. ABE8e shows efficient adenine base editing activity and low indel formation when used with Cas homologues other than SpCas9, for example, SaCas9, SaCas9-KKH, Cas12a homologues, e.g., LbCas12a, enAs-Cas12a, SpCas9-NG and circularly permuted CP1028-SpCas9 and CP1041-SpCas9. In addition to the mutations shown for ABE8e in Table X, off-target RNA and DNA editing were reduced by introducing a V106W substitution into the TadA domain (as described in M. Richter et al., 2020, Nature Biotechnology, doi.org/10.1038/s41587-020-0453-z, the entire contents of which are incorporated by reference herein).

TABLE-US-00086 TABLE 7B Additional Adenosine Deaminase Base Editor 8 Variants ABE8 Base Adenosine Editor Deaminase Adenosine Deaminase Description ABESa-m TadA*8a Monomer_TadA*7.10 + R26C + A109S + T111R + D119N + H122N + Y147D + F149Y + T166I + D167N ABE8b-m TadA*8b Monomer_TadA*7.10 + V88A + A109S + T111R + D119N + H122N + F149Y + T166I + D167N ABE8c-m TadA*8c Monomer_TadA*7.10 + R26C + A109S + T111R + D119N + H122N + F149Y + T166I + D167N ABESd-m TadA*8d Monomer_TadA*7.10 + V88A + T111R + D119N + F149Y ABEZe-m TadA*8e Monomer_TadA*7.10 + A109S + T111R + D119N + H122N + Y147D + F149Y + T166I + D167N ABESa-d TadA*8a Heterodimer_(WT) + (TadA*7.10 + R26C + A109S + T111R + D119N + H122N + Y147D + F149Y + T166I + D167N) ABE8b-d TadA*8b Heterodimer_(WT) + (TadA*7.10 + V88A + A109S + T111R + D119N + H122N + F149Y + T166I + D167N) ABE8c-d TadA*8c Heterodimer_(WT) + (TadA*7.10 + R26C + A109S + T111R + D119N + H122N + F149Y + T166I + D167N) ABE8d-d TadA*8d Heterodimer_(WT) + (TadA*7.10 + V88A + T111R + D119N + F149Y) ABE8e-d TadA*8e Heterodimer_(WT) + (TadA*7.10 + A109S + T111R + D119N + H122N + Y147D + F149Y + T166I + D167N)

[0614] In some embodiments, the base editor further comprises a domain comprising all or a portion of a uracil glycosylase inhibitor (UGI). In some embodiments, the base editor comprises a domain comprising all or a portion of a uracil binding protein (UBP), such as a uracil DNA glycosylase (UDG). In some embodiments, the base editor comprises a domain comprising all or a portion of a nucleic acid polymerase. In some embodiments, a nucleic acid polymerase or portion thereof incorporated into a base editor is a translesion DNA polymerase.

[0615] In some embodiments, a domain of the base editor can comprise multiple domains. For example, the base editor comprising a polynucleotide programmable nucleotide binding domain derived from Cas9 can comprise an REC lobe and an NUC lobe corresponding to the REC lobe and NUC lobe of a wild-type or natural Cas9. In another example, the base editor can comprise one or more of a RuvCI domain, BH domain, REC1 domain, REC2 domain, RuvCII domain, L1 domain, HNH domain, L2 domain, RuvCIII domain, WED domain, TOPO domain or CTD domain. In some embodiments, one or more domains of the base editor comprise a mutation (e.g., substitution, insertion, deletion) relative to a wild type version of a polypeptide comprising the domain. For example, an HNH domain of a polynucleotide programmable DNA binding domain can comprise an H840A substitution. In another example, a RuvCI domain of a polynucleotide programmable DNA binding domain can comprise a D10A substitution.

[0616] Different domains (e.g., adjacent domains) of the base editor disclosed herein can be connected to each other with or without the use of one or more linker domains (e.g., an XTEN linker domain). In some embodiments, a linker domain can be a bond (e.g., covalent bond), chemical group, or a molecule linking two molecules or moieties, e.g., two domains of a fusion protein, such as, for example, a first domain (e.g., Cas9-derived domain) and a second domain (e.g., an adenosine deaminase domain or a cytidine deaminase domain). In some embodiments, a linker is a covalent bond (e.g., a carbon-carbon bond, disulfide bond, carbon-hetero atom bond, etc.). In certain embodiments, a linker is a carbon nitrogen bond of an amide linkage. In certain embodiments, a linker is a cyclic or acyclic, substituted or unsubstituted, branched or unbranched aliphatic or heteroaliphatic linker. In certain embodiments, a linker is polymeric (e.g., polyethylene, polyethylene glycol, polyamide, polyester, etc.). In certain embodiments, a linker comprises a monomer, dimer, or polymer of aminoalkanoic acid. In some embodiments, a linker comprises an aminoalkanoic acid (e.g., glycine, ethanoic acid, alanine, beta-alanine, 3-aminopropanoic acid, 4-aminobutanoic acid, 5-pentanoic acid, etc.). In some embodiments, a linker comprises a monomer, dimer, or polymer of aminohexanoic acid (Ahx). In certain embodiments, a linker is based on a carbocyclic moiety (e.g., cyclopentane, cyclohexane). In other embodiments, a linker comprises a polyethylene glycol moiety (PEG). In certain embodiments, a linker comprises an aryl or heteroaryl moiety. In certain embodiments, the linker is based on a phenyl ring. A linker can include functionalized moieties to facilitate attachment of a nucleophile (e.g., thiol, amino) from the peptide to the linker. Any electrophile can be used as part of the linker. Exemplary electrophiles include, but are not limited to, activated esters, activated amides, Michael acceptors, alkyl halides, aryl halides, acyl halides, and isothiocyanates. In some embodiments, a linker joins a gRNA binding domain of an RNA-programmable nuclease, including a Cas9 nuclease domain, and the catalytic domain of a nucleic acid editing protein. In some embodiments, a linker joins a dCas9 and a second domain (e.g., UGI, cytidine deaminase, etc.).

[0617] Typically, a linker is positioned between, or flanked by, two groups, molecules, or other moieties and connected to each one via a covalent bond, thus connecting the two. In some embodiments, a linker is an amino acid or a plurality of amino acids (e.g., a peptide or protein). In some embodiments, a linker is an organic molecule, group, polymer, or chemical moiety. In some embodiments, a linker is 2-100 amino acids in length, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 30-35, 35-40, 40-45, 45-50, 50-60, 60-70, 70-80, 80-90, 90-100, 100-150, or 150-200 amino acids in length. In some embodiments, the linker is about 3 to about 104 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100) amino acids in length. Longer or shorter linkers are also contemplated. In some embodiments, a linker domain comprises the amino acid sequence SGSETPGTSESATPES, which can also be referred to as the XTEN linker. Any method for linking the fusion protein domains can be employed (e.g., ranging from very flexible linkers of the form (SGGS)n, (GGGS)n, (GGGGS)n, and (G)n, to more rigid linkers of the form (EAAAK)n, (GGS)n, SGSETPGTSESATPES (see, e.g., Guilinger J P, Thompson D B, Liu D R. Fusion of catalytically inactive Cas9 to FokI nuclease improves the specificity of genome modification. Nat. Biotechnol. 2014; 32(6): 577-82; the entire contents are incorporated herein by reference), or (XP)n motif, in order to achieve the optimal length for activity for the nucleobase editor. In some embodiments, n is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. In some embodiments, the linker comprises a (GGS)n motif, wherein n is 1, 3, or 7. In some embodiments, the Cas9 domain of the fusion proteins provided herein are fused via a linker comprising the amino acid sequence SGSETPGTSESATPES. In some embodiments, a linker comprises a plurality of proline residues and is 5-21, 5-14, 5-9, 5-7 amino acids in length, e.g., PAPAP, PAPAPA, PAPAPAP, PAPAPAPA, P(AP)4, P(AP)7, P(AP)10 (see, e.g., Tan J, Zhang F, Karcher D, Bock R. Engineering of high-precision base editors for site-specific single nucleotide replacement. Nat Commun. 2019 Jan. 25; 10(1):439; the entire contents are incorporated herein by reference). Such proline-rich linkers are also termed “rigid” linkers.

Linkers

[0618] In certain embodiments, linkers may be used to link any of the peptides or peptide domains of the invention. The linker may be as simple as a covalent bond, or it may be a polymeric linker many atoms in length. In certain embodiments, the linker is a polypeptide or based on amino acids. In other embodiments, the linker is not peptide-like. In certain embodiments, the linker is a covalent bond (e.g., a carbon-carbon bond, disulfide bond, carbon-heteroatom bond, etc.). In certain embodiments, the linker is a carbon-nitrogen bond of an amide linkage. In certain embodiments, the linker is a cyclic or acyclic, substituted or unsubstituted, branched or unbranched aliphatic or heteroaliphatic linker. In certain embodiments, the linker is polymeric (e.g., polyethylene, polyethylene glycol, polyamide, polyester, etc.). In certain embodiments, the linker comprises a monomer, dimer, or polymer of aminoalkanoic acid. In certain embodiments, the linker comprises an aminoalkanoic acid (e.g., glycine, ethanoic acid, alanine, beta-alanine, 3-aminopropanoic acid, 4-aminobutanoic acid, 5-pentanoic acid, etc.). In certain embodiments, the linker comprises a monomer, dimer, or polymer of aminohexanoic acid (Ahx). In certain embodiments, the linker is based on a carbocyclic moiety (e.g., cyclopentane, cyclohexane). In other embodiments, the linker comprises a polyethylene glycol moiety (PEG). In other embodiments, the linker comprises amino acids. In certain embodiments, the linker comprises a peptide. In certain embodiments, the linker comprises an aryl or heteroaryl moiety. In certain embodiments, the linker is based on a phenyl ring. The linker may include functionalized moieties to facilitate attachment of a nucleophile (e.g., thiol, amino) from the peptide to the linker. Any electrophile may be used as part of the linker. Exemplary electrophiles include, but are not limited to, activated esters, activated amides, Michael acceptors, alkyl halides, aryl halides, acyl halides, and isothiocyanates.

[0619] In some embodiments, the linker is an amino acid or a plurality of amino acids (e.g., a peptide or protein). In some embodiments, the linker is a bond (e.g., a covalent bond), an organic molecule, group, polymer, or chemical moiety. In some embodiments, the linker is about 3 to about 104 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100) amino acids in length.

[0620] In some embodiments, the cytidine deaminase and adenosine deaminase and the napDNAbp are fused via a linker that is 4, 16, 32, or 104 amino acids in length. In some embodiments, the linker is about 3 to about 104 amino acids in length. In some embodiments, any of the fusion proteins provided herein, comprise a cytidine deaminase, adenosine deaminase and a Cas9 domain that are fused to each other via a linker. Various linker lengths and flexibilities between the deaminase domain (e.g., an engineered ecTadA) and the Cas9 domain can be employed (e.g., ranging from very flexible linkers of the form (GGGS).sub.n, (GGGGS).sub.n, and (G).sub.n to more rigid linkers of the form (EAAAK).sub.n, (SGGS).sub.n, SGSETPGTSESATPES (see, e.g., Guilinger J P, Thompson D B, Liu D R. Fusion of catalytically inactive Cas9 to FokI nuclease improves the specificity of genome modification. Nat. Biotechnol. 2014; 32(6): 577-82; the entire contents are incorporated herein by reference) and (XP).sub.n) in order to achieve the optimal length for activity for the nucleobase editor. In some embodiments, n is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. In some embodiments, the linker comprises a (GGS).sub.n motif, wherein n is 1, 3, or 7. In some embodiments, the cytidine deaminase and adenosine deaminase and the Cas9 domain of any of the fusion proteins provided herein are fused via a linker (e.g., an XTEN linker) comprising the amino acid sequence SGSETPGTSESATPES.

[0621] In some embodiments, the target region comprises a target window, wherein the target window comprises the target nucleobase pair. In some embodiments, the target window comprises 1-10 nucleotides. In some embodiments, the target window is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nucleotides in length. In some embodiments, the intended edit of base pair is within the target window. In some embodiments, the target window comprises the intended edit of base pair. In some embodiments, the method is performed using any of the base editors provided herein. In some embodiments, a target window is a deamination window.

[0622] Additionally, in some cases, a Gam protein can be fused to an N terminus of a base editor. In some cases, a Gam protein can be fused to a C-terminus of a base editor. The Gam protein of bacteriophage Mu can bind to the ends of double strand breaks (DSBs) and protect them from degradation. In some embodiments, using Gam to bind the free ends of DSB can reduce indel formation during the process of base editing. In some embodiments, 174-residue Gam protein is fused to the N terminus of the base editors. See. Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017). In some cases, a mutation or mutations can change the length of a base editor domain relative to a wild type domain. For example, a deletion of at least one amino acid in at least one domain can reduce the length of the base editor. In another case, a mutation or mutations do not change the length of a domain relative to a wild type domain. For example, substitution(s) in any domain does/do not change the length of the base editor.

[0623] In some embodiments, the base editing fusion proteins provided herein need to be positioned at a precise location, for example, where a target base is placed within a defined region (e.g., a “deamination window”). In some cases, a target can be within a 4 base region. In some cases, such a defined target region can be approximately 15 bases upstream of the PAM. See Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N. M., et al., “Programmable base editing of A⋅T to G⋅C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); and Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017), the entire contents of which are hereby incorporated by reference.

[0624] A defined target region can be a deamination window. A deamination window can be the defined region in which a base editor acts upon and deaminates a target nucleotide. In some embodiments, the deamination window is within a 2, 3, 4, 5, 6, 7, 8, 9, or 10 base regions. In some embodiments, the deamination window is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 bases upstream of the PAM.

[0625] The base editors of the present disclosure can comprise any domain, feature or amino acid sequence which facilitates the editing of a target polynucleotide sequence. For example, in some embodiments, the base editor comprises a nuclear localization sequence (NLS). In some embodiments, an NLS of the base editor is localized between a deaminase domain and a polynucleotide programmable nucleotide binding domain. In some embodiments, an NLS of the base editor is localized C-terminal to a polynucleotide programmable nucleotide binding domain.

[0626] Other exemplary features that can be present in a base editor as disclosed herein are localization sequences, such as cytoplasmic localization sequences, export sequences, such as nuclear export sequences, or other localization sequences, as well as sequence tags that are useful for solubilization, purification, or detection of the fusion proteins. Suitable protein tags provided herein include, but are not limited to, biotin carboxylase carrier protein (BCCP) tags, myc-tags, calmodulin-tags, FLAG-tags, hemagglutinin (HA)-tags, polyhistidine tags, also referred to as histidine tags or His-tags, maltose binding protein (MBP)-tags, nus-tags, glutathione-S-transferase (GST)-tags, green fluorescent protein (GFP)-tags, thioredoxin-tags, S-tags, Softags (e.g., Softag 1, Softag 3), strep-tags, biotin ligase tags, FlAsH tags, V5 tags, and SBP-tags. Additional suitable sequences will be apparent to those of skill in the art. In some embodiments, the fusion protein comprises one or more His tags.

[0627] Non-limiting examples of protein domains which can be included in the fusion protein include deaminase domains (e.g., cytidine deaminase, adenosine deaminase), a uracil glycosylase inhibitor (UGI) domain, epitope tags, and reporter gene sequences.

[0628] Non-limiting examples of epitope tags include histidine (His) tags, V5 tags, FLAG tags, influenza hemagglutinin (HA) tags, Myc tags, VSV-G tags, and thioredoxin (Trx) tags. Examples of reporter genes include, but are not limited to, glutathione-5-transferase (GST), horseradish peroxidase (HRP), chloramphenicol acetyltransferase (CAT) beta-galactosidase, beta-glucuronidase, luciferase, green fluorescent protein (GFP), HcRed, DsRed, cyan fluorescent protein (CFP), yellow fluorescent protein (YFP), and autofluorescent proteins including blue fluorescent protein (BFP). Additional protein sequences can include amino acid sequences that bind DNA molecules or bind other cellular molecules, including, but not limited to, maltose binding protein (MBP), S-tag, Lex A DNA binding domain (DBD) fusions, GAL4 DNA binding domain fusions, and herpes simplex virus (HSV) BP16 protein fusions.

Base Editor Efficiency

[0629] CRISPR-Cas9 nucleases have been widely used to mediate targeted genome editing. In most genome editing applications, Cas9 forms a complex with a guide polynucleotide (e.g., single guide RNA (sgRNA)) and induces a double-stranded DNA break (DSB) at the target site specified by the sgRNA sequence. Cells primarily respond to this DSB through the non-homologous end-joining (NHEJ) repair pathway, which results in stochastic insertions or deletions (indels) that can cause frameshift mutations that disrupt the gene. In the presence of a donor DNA template with a high degree of homology to the sequences flanking the DSB, gene editing can be achieved through an alternative pathway known as homology directed repair (HDR). Unfortunately, under most non-perturbative conditions, HDR is inefficient, dependent on cell state and cell type, and dominated by a larger frequency of indels. As most of the known genetic variations associated with human disease are point mutations, methods that can more efficiently and cleanly make precise point mutations are needed. Base editing systems as provided herein provide a new way to provide genome editing without generating double-strand DNA breaks, without requiring a donor DNA template, and without inducing an excess of stochastic insertions and deletions.

[0630] The base editors provided herein are capable of modifying a specific nucleotide base without generating a significant proportion of indels. The term “indel(s)”, as used herein, refers to the insertion or deletion of a nucleotide base within a nucleic acid. Such insertions or deletions can lead to frame shift mutations within a coding region of a gene. In some embodiments, it is desirable to generate base editors that efficiently modify (e.g., mutate or deaminate) a specific nucleotide within a nucleic acid, without generating a large number of insertions or deletions (i.e., indels) in the target nucleotide sequence. In certain embodiments, any of the base editors provided herein are capable of generating a greater proportion of intended modifications (e.g., point mutations or deaminations) versus indels.

[0631] In some embodiments, any of base editor systems provided herein result in less than 50%, less than 40%, less than 30%, less than 20%, less than 19%, less than 18%, less than 17%, less than 16%, less than 15%, less than 14%, less than 13%, less than 12%, less than 11%, less than 10%, less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, less than 0.9%, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.4%, less than 0.3%, less than 0.2%, less than 0.1%, less than 0.09%, less than 0.08%, less than 0.07%, less than 0.06%, less than 0.05%, less than 0.04%, less than 0.03%, less than 0.02%, or less than 0.01% indel formation in the target polynucleotide sequence.

[0632] Some aspects of the disclosure are based on the recognition that any of the base editors provided herein are capable of efficiently generating an intended mutation, such as a point mutation, in a nucleic acid (e.g., a nucleic acid within a genome of a subject) without generating a significant number of unintended mutations, such as unintended point mutations. In some embodiments, any of the base editors provided herein are capable of generating at least 0.01% of intended mutations (i.e. at least 0.01% base editing efficiency). In some embodiments, any of the base editors provided herein are capable of generating at least 0.01%, 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, 95%, or 99% of intended mutations.

[0633] In some embodiments, the base editors provided herein are capable of generating a ratio of intended point mutations to indels that is greater than 1:1. In some embodiments, the base editors provided herein are capable of generating a ratio of intended point mutations to indels that is at least 1.5:1, at least 2:1, at least 2.5:1, at least 3:1, at least 3.5:1, at least 4:1, at least 4.5:1, at least 5:1, at least 5.5:1, at least 6:1, at least 6.5:1, at least 7:1, at least 7.5:1, at least 8:1, at least 8.5:1, at least 9:1, at least 10:1, at least 11:1, at least 12:1, at least 13:1, at least 14:1, at least 15:1, at least 20:1, at least 25:1, at least 30:1, at least 40:1, at least 50:1, at least 100:1, at least 200:1, at least 300:1, at least 400:1, at least 500:1, at least 600:1, at least 700:1, at least 800:1, at least 900:1, or at least 1000:1, or more.

[0634] The number of intended mutations and indels can be determined using any suitable method, for example, as described in International PCT Application Nos. PCT/2017/045381 (WO2018/027078) and PCT/US2016/058344 (WO2017/070632); Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N. M., et al., “Programmable base editing of A⋅T to G⋅C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); and Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017); the entire contents of which are hereby incorporated by reference.

[0635] In some embodiments, to calculate indel frequencies, sequencing reads are scanned for exact matches to two 10-bp sequences that flank both sides of a window in which indels can occur. If no exact matches are located, the read is excluded from analysis. If the length of this indel window exactly matches the reference sequence the read is classified as not containing an indel. If the indel window is two or more bases longer or shorter than the reference sequence, then the sequencing read is classified as an insertion or deletion, respectively. In some embodiments, the base editors provided herein can limit formation of indels in a region of a nucleic acid. In some embodiments, the region is at a nucleotide targeted by a base editor or a region within 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides of a nucleotide targeted by a base editor.

[0636] The number of indels formed at a target nucleotide region can depend on the amount of time a nucleic acid (e.g., a nucleic acid within the genome of a cell) is exposed to a base editor. In some embodiments, the number or proportion of indels is determined after at least 1 hour, at least 2 hours, at least 6 hours, at least 12 hours, at least 24 hours, at least 36 hours, at least 48 hours, at least 3 days, at least 4 days, at least 5 days, at least 7 days, at least 10 days, or at least 14 days of exposing the target nucleotide sequence (e.g., a nucleic acid within the genome of a cell) to a base editor. It should be appreciated that the characteristics of the base editors as described herein can be applied to any of the fusion proteins, or methods of using the fusion proteins provided herein.

Multiplex Editing

[0637] In some embodiments, the base editor system provided herein is capable of multiplex editing of a plurality of nucleobase pairs in one or more genes. In some embodiments, the plurality of nucleobase pairs is located in the same gene. In some embodiments, the plurality of nucleobase pairs is located in one or more gene, wherein at least one gene is located in a different locus. In some embodiments, the multiplex editing can comprise one or more guide polynucleotides. In some embodiments, the multiplex editing can comprise one or more base editor system. In some embodiments, the multiplex editing can comprise one or more base editor systems with a single guide polynucleotide. In some embodiments, the multiplex editing can comprise one or more base editor system with a plurality of guide polynucleotides. In some embodiments, the multiplex editing can comprise one or more guide polynucleotide with a single base editor system. In some embodiments, the multiplex editing can comprise at least one guide polynucleotide that does not require a PAM sequence to target binding to a target polynucleotide sequence. In some embodiments, the multiplex editing can comprise at least one guide polynucleotide that requires a PAM sequence to target binding to a target polynucleotide sequence. In some embodiments, the multiplex editing can comprise a mix of at least one guide polynucleotide that does not require a PAM sequence to target binding to a target polynucleotide sequence and at least one guide polynucleotide that require a PAM sequence to target binding to a target polynucleotide sequence. It should be appreciated that the characteristics of the multiplex editing using any of the base editors as described herein can be applied to any of combination of the methods of using any of the base editor provided herein. It should also be appreciated that the multiplex editing using any of the base editors as described herein can comprise a sequential editing of a plurality of nucleobase pairs.

[0638] In some embodiments, the plurality of nucleobase pairs are in one more genes. In some embodiments, the plurality of nucleobase pairs is in the same gene. In some embodiments, at least one gene in the one more genes is located in a different locus.

[0639] In some embodiments, the editing is editing of the plurality of nucleobase pairs in at least one protein coding region. In some embodiments, the editing is editing of the plurality of nucleobase pairs in at least one protein non-coding region. In some embodiments, the editing is editing of the plurality of nucleobase pairs in at least one protein coding region and at least one protein non-coding region.

[0640] In some embodiments, the editing is in conjunction with one or more guide polynucleotides. In some embodiments, the base editor system can comprise one or more base editor system. In some embodiments, the base editor system can comprise one or more base editor systems in conjunction with a single guide polynucleotide. In some embodiments, the base editor system can comprise one or more base editor system in conjunction with a plurality of guide polynucleotides. In some embodiments, the editing is in conjunction with one or more guide polynucleotide with a single base editor system. In some embodiments, the editing is in conjunction with at least one guide polynucleotide that does not require a PAM sequence to target binding to a target polynucleotide sequence. In some embodiments, the editing is in conjunction with at least one guide polynucleotide that require a PAM sequence to target binding to a target polynucleotide sequence. In some embodiments, the editing is in conjunction with a mix of at least one guide polynucleotide that does not require a PAM sequence to target binding to a target polynucleotide sequence and at least one guide polynucleotide that require a PAM sequence to target binding to a target polynucleotide sequence. It should be appreciated that the characteristics of the multiplex editing using any of the base editors as described herein can be applied to any of combination of the methods of using any of the base editors provided herein. It should also be appreciated that the editing can comprise a sequential editing of a plurality of nucleobase pairs.

Methods of Using Base Editors

[0641] The editing of SDS-associated genes to permit transcription opens up new strategies for gene editing with applications in therapeutics and basic research.

[0642] The present disclosure provides methods for the treatment of a subject diagnosed with a disease (e.g., SDS) associated with or caused by gene conversion, as well as by point mutations that affect splicing (e.g., alter a splice donor or acceptor site) that can be corrected by a base editor system provided herein. For example, in some embodiments, a method is provided that comprises administering to a subject having such a disease, e.g., a disease caused by a gene conversion or other genetic mutation, an effective amount of a nucleobase editor (e.g., an adenosine deaminase base editor or a cytidine deaminase base editor) that edits the gene conversion such that splicing is permitted or that edits another mutation in the disease associated genes a (e.g., converts a stop codon to a missense mutation, inserts a splice acceptor or donor site, or corrects a splice donor or acceptor site comprising a mutation).

[0643] In a certain aspect, methods are provided for the treatment of SDS, which is associated or caused by a mutation (e.g., gene conversion) in the SBDS (including an SBDSP) gene encoding the SBDS protein, which results in aberrant gene splicing and/or premature protein truncation. The effects of gene conversion can be ameliorated by deaminase-mediated gene editing, which introduces, for example, a point mutation that permits transcription or permits normal splicing.

[0644] It will be understood that the numbering of the specific positions or residues in the respective sequences, e.g., polynucleotide or amino acid sequences of a disease-related gene or its encoded protein, respectively, depends on the particular protein and numbering scheme used. Numbering can be different, e.g., in precursors of a mature protein and the mature protein itself, and differences in sequences from species to species can affect numbering. One of skill in the art will be able to identify the respective residue in any homologous protein and in the respective encoding nucleic acid by methods well known in the art, e.g., by sequence alignment and determination of homologous residues.

[0645] Provided herein are methods of using the base editor or base editor system for editing a nucleobase in a target nucleotide sequence associated with a disease or disorder. In some embodiments, the activity of the base editor (e.g., comprising an adenosine deaminase and a Cas9 domain) results in editing of a gene conversion or correction of a point mutation (e.g., a mutation that alters a splice acceptor or donor site). In some embodiments, the target DNA sequence comprises a G.fwdarw.A point mutation associated with a disease or disorder, and wherein the deamination of the mutant A base results in a sequence that is not associated with a disease or disorder. In some embodiments, the target DNA sequence comprises a T.fwdarw.C point mutation associated with a disease or disorder, and wherein the deamination of the mutant C base results in a sequence that is not associated with a disease or disorder. In other embodiments, the target DNA sequence has been altered by a gene conversion event that disrupts splicing, and the deamination of a site within the gene conversion permits transcription and splicing.

[0646] In some embodiments, the target DNA sequence encodes a protein (e.g., SBDS protein), and the point mutation is in a codon and results in a change in the amino acid encoded by the mutant codon as compared to the wild-type codon. In some embodiments, the deamination of the mutant A results in a change of the amino acid encoded by the mutant codon. In some embodiments, the deamination of the mutant A results in the codon encoding the wild-type amino acid. In some embodiments, the deamination of the mutant C results in a change of the amino acid encoded by the mutant codon. In some embodiments, the deamination of the mutant C results in the codon encoding the wild-type amino acid. In some embodiments, the subject has or has been diagnosed with a disease or disorder.

[0647] In some embodiments, the adenosine deaminases provided herein are capable of deaminating adenine of a deoxyadenosine residue of DNA. Other aspects of the disclosure provide fusion proteins that comprise an adenosine deaminase (e.g., an adenosine deaminase that deaminates deoxyadenosine in DNA as described herein) and a domain (e.g., a Cas9 or a Cpf1 protein) capable of binding to a specific nucleotide sequence. For example, the adenosine can be converted to an inosine residue, which typically base pairs with a cytosine residue. Such fusion proteins are useful inter alia for targeted editing of nucleic acid sequences. Such fusion proteins can be used for targeted editing of DNA in vitro, e.g., for the generation of mutant cells or animals; for the introduction of targeted mutations, e.g., for the correction or editing of genetic defects in cells ex vivo, e.g., in cells obtained from a subject that are subsequently re-introduced into the same or another subject; and for the introduction of targeted mutations in vivo, e.g., the editing of genetic defects to permit transcription can be treated using the nucleobase editors provided herein. The present disclosure provides deaminases, fusion proteins, nucleic acids, vectors, cells, compositions, methods, kits, systems, etc. that utilize the deaminases and nucleobase editors.

Generating an Intended Mutation

[0648] In some embodiments, the purpose of the methods provided herein is to restore the function of a dysfunctional gene via gene editing. In some embodiments, the function of a dysfunctional gene is restored by introducing an intended mutation that permits splicing. The nucleobase editing proteins provided herein can be validated for gene editing-based human therapeutics in vitro, e.g., by editing a disease-associated mutation (e.g., gene conversion) in human cell culture. It will be understood by the skilled artisan that the nucleobase editing proteins provided herein, e.g., the fusion proteins comprising a polynucleotide programmable nucleotide binding domain (e.g., Cas9) and a nucleobase editing domain (e.g., an adenosine deaminase domain or a cytidine deaminase domain) can be used to correct any single point A to G or C to T mutation. In the first case, deamination of the mutant A to I corrects the mutation, and in the latter case, deamination of the A that is base-paired with the mutant T, followed by a round of replication, corrects the mutation. In some embodiments, the editing does not produce a correction, but introduces an alteration that permits transcription.

[0649] In some embodiments, the present disclosure provides base editors that can efficiently generate an intended mutation, such as a point mutation, in a nucleic acid (e.g., a nucleic acid within a genome of a subject) without generating a significant number of unintended mutations, such as unintended point mutations. In some embodiments, an intended mutation is a mutation that is generated by a specific base editor (e.g., cytidine base editor or adenosine base editor) bound to a guide polynucleotide (e.g., gRNA), specifically designed to generate the intended mutation. In some embodiments, the intended mutation is a mutation associated with a disease or disorder. In some embodiments, the intended mutation is an adenine (A) to guanine (G) point mutation associated with a disease or disorder. In some embodiments, the intended mutation is a cytosine (C) to thymine (T) point mutation associated with a disease or disorder. In some embodiments, the intended mutation is an adenine (A) to guanine (G) point mutation within the coding region or non-coding region of a gene. In some embodiments, the intended mutation is a cytosine (C) to thymine (T) point mutation within the coding region or non-coding region of a gene. In some embodiments, the intended mutation is a point mutation that generates a stop codon, for example, a premature stop codon within the coding region of a gene. In some embodiments, the intended mutation is a mutation that eliminates a stop codon.

[0650] In some embodiments, any of the base editors provided herein are capable of generating a ratio of intended mutations to unintended mutations (e.g., intended point mutations:unintended point mutations) that is greater than 1:1. In some embodiments, any of the base editors provided herein are capable of generating a ratio of intended mutations to unintended mutations (e.g., intended point mutations:unintended point mutations) that is at least 1.5:1, at least 2:1, at least 2.5:1, at least 3:1, at least 3.5:1, at least 4:1, at least 4.5:1, at least 5:1, at least 5.5:1, at least 6:1, at least 6.5:1, at least 7:1, at least 7.5:1, at least 8:1, at least 10:1, at least 12:1, at least 15:1, at least 20:1, at least 25:1, at least 30:1, at least 40:1, at least 50:1, at least 100:1, at least 150:1, at least 200:1, at least 250:1, at least 500:1, or at least 1000:1, or more

[0651] Details of base editor efficiency are described in International PCT Application Nos. PCT/2017/045381 (WO2018/027078) and PCT/US2016/058344 (WO2017/070632), each of which is incorporated herein by reference for its entirety. Also see Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N. M., et al., “Programmable base editing of A⋅T to G⋅C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); and Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017), the entire contents of which are hereby incorporated by reference.

[0652] In some embodiments, the editing of the plurality of nucleobase pairs in one or more genes result in formation of at least one intended mutation. In some embodiments, the formation of the at least one intended mutation results in a precise correction of a disease causing mutation. In other embodiments, the editing introduces an alteration that permits transcription of the target gene. Such alteration includes insertion of a splice donor or acceptor site, introduction of a missense mutation that alters a stop codon and permits transcription, or correction or introduction of a splice codon. It should be appreciated that the characteristics of the multiplex editing of the base editors as described herein can be applied to any combination of the methods of using the base editor provided herein.

Editing of Pathogenic Mutations in an SBDS Polynucleotide

[0653] In one embodiment, the intended mutation alters a stop codon introduced by a gene conversion event, which stop codon results in the premature truncation of the SBDS polypeptide, and introduces a point mutation that is permissive for transcription. In another embodiment, the point mutation introduces a new splice acceptor or splice donor site that restores splicing of an SBDS gene that has undergone gene conversion or that comprises a point mutation that causes aberrant splicing. In some embodiments, the insertion of a new splice acceptor or splice donor site does not restore normal splicing, but nevertheless permits expression of an SBDS protein having wild-type activity or having sufficient activity to have a therapeutic effect when expressed in the cells of a subject having or at risk of developing SDS.

[0654] In some embodiments, the intended mutation is a precise correction of a pathogenic mutation or a disease-causing mutation in a splice site (e.g., donor or acceptor) in the SBDS gene associated with SDS. In some embodiments, the pathogenic mutation is a G.fwdarw.A point mutation associated with a disease or disorder, wherein the deamination of the mutant A base with an A-to-G base editor (ABE) results in a sequence that is not associated with a disease or disorder. In some embodiments, the pathogenic mutation is a C.fwdarw.T point mutation. The C.fwdarw.T point mutation can be corrected, for example, by targeting an A-to-G base editor (ABE) to the opposite strand and editing the complement A of the pathogenic T nucleobase. In some embodiments, the pathogenic mutation is a T.fwdarw.C point mutation associated with a disease or disorder, and wherein the deamination of the mutant C base with a C-to-T base editor (BE or CBE) results in a sequence that is not associated with a disease or disorder. In some embodiments, the pathogenic mutation is an A.fwdarw.G point mutation. The A.fwdarw.G point mutation can be corrected, for example, by targeting a CBE to the opposite strand and editing the complement C of the pathogenic G nucleobase. In some embodiments, the mutation is a 258+2T>C mutation in a SBDS gene that causes aberrant splicing and/or a frameshift. In other embodiments, the mutation is a 83-184TA>CT mutation in a SBDS gene that causes aberrant splicing and/or a frameshift.

Delivery System

[0655] A base editor disclosed herein can be encoded on a nucleic acid that is contained in a viral vector. Viral vectors can include lentivirus, Adenovirus, Retrovirus, and Adeno-associated viruses (AAVs). Viral vectors can be selected based on the application. For example, AAVs are commonly used for gene delivery in vivo due to their mild immunogenicity. Adenoviruses are commonly used as vaccines because of the strong immunogenic response they induce. Packaging capacity of the viral vectors can limit the size of the base editor that can be packaged into the vector. For example, the packaging capacity of the AAVs is ˜4.5 kb including two 145 base inverted terminal repeats (ITRs).

[0656] AAV is a small, single-stranded DNA dependent virus belonging to the parvovirus family. The 4.7 kb wild-type (wt) AAV genome is made up of two genes that encode four replication proteins and three capsid proteins, respectively, and is flanked on either side by 145-bp inverted terminal repeats (ITRs). The virion is composed of three capsid proteins, Vp1, Vp2, and Vp3, produced in a 1:1:10 ratio from the same open reading frame but from differential splicing (Vp1) and alternative translational start sites (Vp2 and Vp3, respectively). Vp3 is the most abundant subunit in the virion and participates in receptor recognition at the cell surface defining the tropism of the virus. A phospholipase domain, which functions in viral infectivity, has been identified in the unique N terminus of Vp1.

[0657] Similar to wt AAV, recombinant AAV (rAAV) utilizes the cis-acting 145-bp ITRs to flank vector transgene cassettes, providing up to 4.5 kb for packaging of foreign DNA. Subsequent to infection, rAAV can express a fusion protein of the invention and persist without integration into the host genome by existing episomally in circular head-to-tail concatemers. Although there are numerous examples of rAAV success using this system, in vitro and in vivo, the limited packaging capacity has limited the use of AAV-mediated gene delivery when the length of the coding sequence of the gene is equal or greater in size than the wt AAV genome.

[0658] The small packaging capacity of AAV vectors makes the delivery of a number of genes that exceed this size and/or the use of large physiological regulatory elements challenging. These challenges can be addressed, for example, by dividing the protein(s) to be delivered into two or more fragments, wherein the N-terminal fragment is fused to a split intein-N and the C-terminal fragment is fused to a split intein-C. These fragments are then packaged into two or more AAV vectors. As used herein, “intein” refers to a self-splicing protein intron (e.g., peptide) that ligates flanking N-terminal and C-terminal exteins (e.g., fragments to be joined). The use of certain inteins for joining heterologous protein fragments is described, for example, in Wood et al., J. Biol. Chem. 289(21); 14512-9 (2014). For example, when fused to separate protein fragments, the inteins IntN and IntC recognize each other, splice themselves out and simultaneously ligate the flanking N- and C-terminal exteins of the protein fragments to which they were fused, thereby reconstituting a full-length protein from the two protein fragments. Other suitable inteins will be apparent to a person of skill in the art.

[0659] A fragment of a fusion protein of the invention can vary in length. In some embodiments, a protein fragment ranges from 2 amino acids to about 1000 amino acids in length. In some embodiments, a protein fragment ranges from about 5 amino acids to about 500 amino acids in length. In some embodiments, a protein fragment ranges from about 20 amino acids to about 200 amino acids in length. In some embodiments, a protein fragment ranges from about 10 amino acids to about 100 amino acids in length. Suitable protein fragments of other lengths will be apparent to a person of skill in the art.

[0660] In some embodiments, a portion or fragment of a nuclease (e.g., Cas9) is fused to an intein. The nuclease can be fused to the N-terminus or the C-terminus of the intein. In some embodiments, a portion or fragment of a fusion protein is fused to an intein and fused to an AAV capsid protein. The intein, nuclease and capsid protein can be fused together in any arrangement (e.g., nuclease-intein-capsid, intein-nuclease-capsid, capsid-intein-nuclease, etc.). In some embodiments, the N-terminus of an intein is fused to the C-terminus of a fusion protein and the C-terminus of the intein is fused to the N-terminus of an AAV capsid protein.

[0661] In one embodiment, dual AAV vectors are generated by splitting a large transgene expression cassette in two separate halves (5′ and 3′ ends, or head and tail), where each half of the cassette is packaged in a single AAV vector (of <5 kb). The re-assembly of the full-length transgene expression cassette is then achieved upon co-infection of the same cell by both dual AAV vectors followed by: (1) homologous recombination (HR) between 5′ and 3′ genomes (dual AAV overlapping vectors); (2) ITR-mediated tail-to-head concatemerization of 5′ and 3′ genomes (dual AAV trans-splicing vectors); or (3) a combination of these two mechanisms (dual AAV hybrid vectors). The use of dual AAV vectors in vivo results in the expression of full-length proteins. The use of the dual AAV vector platform represents an efficient and viable gene transfer strategy for transgenes of >4.7 kb in size.

[0662] The disclosed strategies for designing base editors can be useful for generating base editors capable of being packaged into a viral vector. The use of RNA or DNA viral based systems for the delivery of a base editor takes advantage of highly evolved processes for targeting a virus to specific cells in culture or in the host and trafficking the viral payload to the nucleus or host cell genome. Viral vectors can be administered directly to cells in culture, patients (in vivo), or they can be used to treat cells in vitro, and the modified cells can optionally be administered to patients (ex vivo). Conventional viral based systems could include retroviral, lentivirus, adenoviral, adeno-associated and herpes simplex virus vectors for gene transfer. Integration in the host genome is possible with the retrovirus, lentivirus, and adeno-associated virus gene transfer methods, often resulting in long term expression of the inserted transgene. Additionally, high transduction efficiencies have been observed in many different cell types and target tissues.

[0663] The tropism of a retrovirus can be altered by incorporating foreign envelope proteins, expanding the potential target population of target cells. Lentiviral vectors are retroviral vectors that are able to transduce or infect non-dividing cells and typically produce high viral titers. Selection of a retroviral gene transfer system would therefore depend on the target tissue. Retroviral vectors are comprised of cis-acting long terminal repeats with packaging capacity for up to 6-10 kb of foreign sequence. The minimum cis-acting LTRs are sufficient for replication and packaging of the vectors, which are then used to integrate the therapeutic gene into the target cell to provide permanent transgene expression. Widely used retroviral vectors include those based upon murine leukemia virus (MuLV), gibbon ape leukemia virus (GaLV), Simian Immuno deficiency virus (SIV), human immuno deficiency virus (HIV), and combinations thereof (See, e.g., Buchscher et al., J. Virol. 66:2731-2739 (1992); Johann et al., J. Virol. 66:1635-1640 (1992); Sommnerfelt et al., Virol. 176:58-59 (1990); Wilson et al., J. Virol. 63:2374-2378 (1989); Miller et al., J. Virol. 65:2220-2224 (1991); PCT/US94/05700).

[0664] Retroviral vectors, especially lentiviral vectors, can require polynucleotide sequences smaller than a given length for efficient integration into a target cell. For example, retroviral vectors of length greater than 9 kb can result in low viral titers compared with those of smaller size. In some aspects, a base editor of the present disclosure is of sufficient size so as to enable efficient packaging and delivery into a target cell via a retroviral vector. In some cases, a base editor is of a size so as to allow efficient packing and delivery even when expressed together with a guide nucleic acid and/or other components of a targetable nuclease system.

[0665] In applications where transient expression is preferred, adenoviral based systems can be used. Adenoviral based vectors are capable of very high transduction efficiency in many cell types and do not require cell division. With such vectors, high titer and levels of expression have been obtained. This vector can be produced in large quantities in a relatively simple system. Adeno-associated virus (“AAV”) vectors can also be used to transduce cells with target nucleic acids, e.g., in the in vitro production of nucleic acids and peptides, and for in vivo and ex vivo gene therapy procedures (See, e.g., West et al., Virology 160:38-47 (1987); U.S. Pat. No. 4,797,368; WO 93/24641; Kotin, Human Gene Therapy 5:793-801 (1994); Muzyczka, J. Clin. Invest. 94:1351 (1994). The construction of recombinant AAV vectors is described in a number of publications, including U.S. Pat. No. 5,173,414; Tratschin et al., Mol. Cell. Biol. 5:3251-3260 (1985); Tratschin, et al., Mol. Cell. Biol. 4:2072-2081 (1984); Hermonat & Muzyczka, PNAS 81:6466-6470 (1984); and Samulski et al., J. Virol. 63:03822-3828 (1989).

[0666] A base editor described herein can therefore be delivered with viral vectors. One or more components of the base editor system can be encoded on one or more viral vectors. For example, a base editor and guide nucleic acid can be encoded on a single viral vector. In other cases, the base editor and guide nucleic acid are encoded on different viral vectors. In either case, the base editor and guide nucleic acid can each be operably linked to a promoter and terminator.

[0667] The combination of components encoded on a viral vector can be determined by the cargo size constraints of the chosen viral vector.

Non-Viral Delivery of Base Editors

[0668] Non-viral delivery approaches for base editors are also available. One important category of non-viral nucleic acid vectors are nanoparticles, which can be organic or inorganic. Nanoparticles are well known in the art. Any suitable nanoparticle design can be used to deliver genome editing system components or nucleic acids encoding such components. For instance, organic (e.g. lipid and/or polymer) nanoparticles can be suitable for use as delivery vehicles in certain embodiments of this disclosure. Exemplary lipids for use in nanoparticle formulations, and/or gene transfer are shown in Table 8 (below).

TABLE-US-00087 TABLE 8 Lipids Used for Gene Transfer Lipid Abbreviation Feature 1,2-Dioleoyl-sn-glycero-3-phosphatidylcholine DOPC Helper 1,2-Dioleoyl-sn-glycero-3-phosphatidylethanolamine DOPE Helper Cholesterol Helper N-[1-(2,3-Dioleyloxy)prophyl]N,N,N-trimethylammonium DOTMA Cationic chloride 1,2-Dioleoyloxy-3-trimethylammonium-propane DOTAP Cationic Dioctadecylamidoglycylspermine DOGS Cationic N-(3-Aminopropyl)-N,N-dimethyl-2,3-bis(dodecyloxy)-1- GAP-DLRIE Cationic propanaminium bromide Cetyltrimethylammonium bromide CTAB Cationic 6-Lauroxyhexyl omithinate LHON Cationic l-(2,3-Dioleoyloxypropyl)-2,4,6-trimethylpyridinium 2Oc Cationic 2,3-Dioleyloxy-N-[2(sperminecarboxamido-ethyl]-N,N- DOSPA Cationic dimethyl-1-propanaminium trifluoroacetate 1,2-Dioleyl-3-trimethylammonium-propane DOPA Cationic N-(2-Hydroxyethyl)-N,N-dimethyl-2,3-bis(tetradecyloxy)-1- MDRIE Cationic propanaminium bromide Dimyristooxypropyl dimethyl hydroxyethyl ammonium bromide DMRI Cationic 3p-[N-(N′,N′-Dimethylaminoethane)-carbamoyl]cholesterol DC-Chol Cationic Bis-guanidium-tren-cholesterol BGTC Cationic l13-Diodeoxy-2-(6-carboxy-spermyl)-propylamide DOSPER Cationic Dimethyloctadecylammonium bromide DDAB Cationic Dioctadecylamidoglicylspermidin DSL Cationic rac-[(2,3-Dioctadecyloxypropyl)(2-hydroxyethyl)]- CLIP-1 Cationic dimethylammonium chloride rac-[2(2,3-Dihexadecyloxypropyl- CLIP-6 Cationic oxymethyloxy)ethyl]trimethylammoniun bromide Ethyldimyristoylphosphatidylcholine EDMPC Cationic 1,2-Distearyloxy-N,N-dimethyl-3-aminopropane DSDMA Cationic 1,2-Dimyristoyl-trimethylammonium propane DMTAP Cationic O,O′-Dimyristyl-N-lysyl aspartate DMKE Cationic 1,2-Distearoyl-sn-glycero-3-ethylpho sphocholine DSEPC Cationic N-Palmitoyl D-erythro-sphingosyl carbamoyl-spermine CCS Cationic N-t-Butyl-N0-tetradecyl-3-tetradecylaminopropionamidine diC14-amidine Cationic Octadecenolyoxy[ethyl-2-heptadecenyl-3 hydroxyethyl] DOTIM Cationic imidazolinium chloride N1-Cholesteryloxycarbonyl-3,7-diazanonane-1,9-diamine CDAN Cationic 2-(3-[Bis(3-amino-propyl)-amino]propylamino)-N- RPR209120 Cationic ditetradecylcarbamoylme-ethyl-acetamide 1,2-dilinoleyloxy-3-dimethylaminopropane DLinDMA Cationic 2,2-dilinoleyl-4-dimethylaminoethyl-[1,3]-dioxolane DLin-KC2-DMA Cationic dilinoleyl-methyl-4-dimethylaminobutyrate DLin-MC3-DMA Cationic
Table 9 lists exemplary polymers for use in gene transfer and/or nanoparticle formulations.

TABLE-US-00088 TABLE 9 Polymers Used for Gene Transfer Polymer Abbreviation Poly(ethylene)glycol PEG Polyethylenimine PEI Dithiobis(succinimidylpropionate) DSP Dimethyl-3,3′-dithiobispropionimidate DTBP Polyethylene imine )biscarbamate PEIC Poly(L-lysine) PLL Histidine modified PLL Poly(N-vinylpyrrolidone) PVP Poly(propylenimine) PPI Poly(amidoamine) PAMAM Poly(amidoethylenimine) SS-PAEI Triethylenetetramine TETA Poly(β-aminoester) Poly(4-hydroxy-L-proline ester) PHP Poly(allylamine) Poly(α-[4-aminobutyl]-L-glycolic acid) PAGA Poly(D,L-lactic-co-glycolic acid) PLGA Poly(N-ethyl-4-vinylpyridinium bromide) Poly(phosphazene)s PPZ Poly(phosphoester)s PPE Poly(phosphoramidate)s PPA Poly(N-2-hydroxypropylmethacrylamide) pHPMA Poly(2-(dimethylamino)ethyl methacrylate) pDMAEMA Poly(2-aminoethyl propylene phosphate) PPE-EA Chitosan Galactosylated chitosan N-Dodacylated chitosan Histone Collagen D-SPM Dextran-spermine
Table 10 summarizes delivery methods for a polynucleotide encoding a fusion protein described herein.

TABLE-US-00089 TABLE 10 Delivery into Type of Non-Dividing Duration of Genome Molecule Delivery Vector/Mode Cells Expression Integration Delivered Physical (e.g.. YES Transient NO Nucleic Acids electroporation, and Proteins particle gun, Calcium Phosphate transfection Viral Retrovirus NO Stable YES RNA Lentivirus YES Stable YES/NO with RNA modification Adenovirus YES Transient NO DNA Adeno- YES Stable NO DNA Associated Virus (AAV) Vaccinia Virus YES Very NO DNA Transient Herpes Simplex YES Stable NO DNA Virus Non-Viral Cationic YES Transient Depends on Nucleic Acids Liposomes what is and Proteins delivered Polymeric YES Transient Depends on Nucleic Acids Nanoparticles what is and Proteins delivered Biological Attenuated YES Transient NO Nucleic Acids Non-Viral Bacteria Delivery Engineered YES Transient NO Nucleic Acids Vehicles Bacteriophages Mammalian YES Transient NO Nucleic Acids Virus-like Particles Biological YES Transient NO Nucleic Acids liposomes: Erythrocyte Ghosts and Exosomes

[0669] In another aspect, the delivery of genome editing system components or nucleic acids encoding such components, for example, a nucleic acid binding protein such as, for example, Cas9 or variants thereof, and a gRNA targeting a genomic nucleic acid sequence of interest, may be accomplished by delivering a ribonucleoprotein (RNP) to cells. The RNP comprises the nucleic acid binding protein, e.g., Cas9, in complex with the targeting gRNA. RNPs may be delivered to cells using known methods, such as electroporation, nucleofection, or cationic lipid-mediated methods, for example, as reported by Zuris, J. A. et al., 2015, Nat. Biotechnology, 33(1):73-80. RNPs are advantageous for use in CRISPR base editing systems, particularly for cells that are difficult to transfect, such as primary cells. In addition, RNPs can also alleviate difficulties that may occur with protein expression in cells, especially when eukaryotic promoters, e.g., CMV or EF1A, which may be used in CRISPR plasmids, are not well-expressed. Advantageously, the use of RNPs does not require the delivery of foreign DNA into cells. Moreover, because an RNP comprising a nucleic acid binding protein and gRNA complex is degraded over time, the use of RNPs has the potential to limit off-target effects. In a manner similar to that for plasmid based techniques, RNPs can be used to deliver binding protein (e.g., Cas9 variants) and to direct homology directed repair (HDR).

[0670] A promoter used to drive base editor coding nucleic acid molecule expression can include AAV ITR. This can be advantageous for eliminating the need for an additional promoter element, which can take up space in the vector. The additional space freed up can be used to drive the expression of additional elements, such as a guide nucleic acid or a selectable marker. ITR activity is relatively weak, so it can be used to reduce potential toxicity due to over expression of the chosen nuclease.

[0671] Any suitable promoter can be used to drive expression of the base editor and, where appropriate, the guide nucleic acid. For ubiquitous expression, promoters that can be used include CMV, CAG, CBh, PGK, SV40, Ferritin heavy or light chains, etc. For brain or other CNS cell expression, suitable promoters can include: Synapsin1 for all neurons, CaMKIIalpha for excitatory neurons, GAD67 or GAD65 or VGAT for GABAergic neurons, etc. For liver cell expression, suitable promoters include the Albumin promoter. For lung cell expression, suitable promoters can include SP-B. For endothelial cells, suitable promoters can include ICAM. For hematopoietic cells suitable promoters can include IFNbeta or CD45. For Osteoblasts suitable promoters can include OG-2.

[0672] In some cases, a base editor of the present disclosure is of small enough size to allow separate promoters to drive expression of the base editor and a compatible guide nucleic acid within the same nucleic acid molecule. For instance, a vector or viral vector can comprise a first promoter operably linked to a nucleic acid encoding the base editor and a second promoter operably linked to the guide nucleic acid.

[0673] The promoter used to drive expression of a guide nucleic acid can include: Pol III promoters such as U6 or H1 Use of Pol II promoter and intronic cassettes to express gRNA Adeno Associated Virus (AAV).

[0674] A base editor described herein with or without one or more guide nucleic can be delivered using adeno associated virus (AAV), lentivirus, adenovirus or other plasmid or viral vector types, in particular, using formulations and doses from, for example, U.S. Pat. No. 8,454,972 (formulations, doses for adenovirus), U.S. Pat. No. 8,404,658 (formulations, doses for AAV) and U.S. Pat. No. 5,846,946 (formulations, doses for DNA plasmids) and from clinical trials and publications regarding the clinical trials involving lentivirus, AAV and adenovirus. For example, for AAV, the route of administration, formulation and dose can be as in U.S. Pat. No. 8,454,972 and as in clinical trials involving AAV. For Adenovirus, the route of administration, formulation and dose can be as in U.S. Pat. No. 8,404,658 and as in clinical trials involving adenovirus. For plasmid delivery, the route of administration, formulation and dose can be as in U.S. Pat. No. 5,846,946 and as in clinical studies involving plasmids. Doses can be based on or extrapolated to an average 70 kg individual (e.g. a male adult human), and can be adjusted for patients, subjects, mammals of different weight and species. Frequency of administration is within the ambit of the medical or veterinary practitioner (e.g., physician, veterinarian), depending on usual factors including the age, sex, general health, other conditions of the patient or subject and the particular condition or symptoms being addressed. The viral vectors can be injected into the tissue of interest. For cell-type specific base editing, the expression of the base editor and optional guide nucleic acid can be driven by a cell-type specific promoter.

[0675] For in vivo delivery, AAV can be advantageous over other viral vectors. In some cases, AAV allows low toxicity, which can be due to the purification method not requiring ultra-centrifugation of cell particles that can activate the immune response. In some cases, AAV allows low probability of causing insertional mutagenesis because it doesn't integrate into the host genome.

[0676] AAV has a packaging limit of 4.5 or 4.75 Kb. This means disclosed base editor as well as a promoter and transcription terminator can fit into a single viral vector. Constructs larger than 4.5 or 4.75 Kb can lead to significantly reduced virus production. For example, SpCas9 is quite large, the gene itself is over 4.1 Kb, which makes it difficult for packing into AAV. Therefore, embodiments of the present disclosure include utilizing a disclosed base editor which is shorter in length than conventional base editors. In some examples, the base editors are less than 4 kb. Disclosed base editors can be less than 4.5 kb, 4.4 kb, 4.3 kb, 4.2 kb, 4.1 kb, 4 kb, 3.9 kb, 3.8 kb, 3.7 kb, 3.6 kb, 3.5 kb, 3.4 kb, 3.3 kb, 3.2 kb, 3.1 kb, 3 kb, 2.9 kb, 2.8 kb, 2.7 kb, 2.6 kb, 2.5 kb, 2 kb, or 1.5 kb. In some cases, the disclosed base editors are 4.5 kb or less in length.

[0677] An AAV can be AAV1, AAV2, AAV5 or any combination thereof. One can select the type of AAV with regard to the cells to be targeted; e.g., one can select AAV serotypes 1, 2, 5 or a hybrid capsid AAV1, AAV2, AAV5 or any combination thereof for targeting brain or neuronal cells; and one can select AAV4 for targeting cardiac tissue. AAV8 is useful for delivery to the liver. A tabulation of certain AAV serotypes as to these cells can be found in Grimm, D. et al, J. Virol. 82: 5887-5911 (2008)).

[0678] Lentiviruses are complex retroviruses that have the ability to infect and express their genes in both mitotic and post-mitotic cells. The most commonly known lentivirus is the human immunodeficiency virus (HIV), which uses the envelope glycoproteins of other viruses to target a broad range of cell types.

[0679] Lentiviruses can be prepared as follows. After cloning pCasES10 (which contains a lentiviral transfer plasmid backbone), HEK293FT at low passage (p=5) were seeded in a T-75 flask to 50% confluence the day before transfection in DMEM with 10% fetal bovine serum and without antibiotics. After 20 hours, media is changed to OptiMEM (serum-free) media and transfection was done 4 hours later. Cells are transfected with 10 μg of lentiviral transfer plasmid (pCasES10) and the following packaging plasmids: 5 μg of pMD2.G (VSV-g pseudotype), and 7.5 μg of psPAX2 (gag/pol/rev/tat). Transfection can be done in 4 mL OptiMEM with a cationic lipid delivery agent (50 μl Lipofectamine 2000 and 100 ul Plus reagent). After 6 hours, the media is changed to antibiotic-free DMEM with 10% fetal bovine serum. These methods use serum during cell culture, but serum-free methods are preferred.

[0680] Lentivirus can be purified as follows. Viral supernatants are harvested after 48 hours. Supernatants are first cleared of debris and filtered through a 0.45 μm low protein binding (PVDF) filter. They are then spun in an ultracentrifuge for 2 hours at 24,000 rpm. Viral pellets are resuspended in 50 μl of DMEM overnight at 4° C. They are then aliquoted and immediately frozen at −80° C.

[0681] In another embodiment, minimal non-primate lentiviral vectors based on the equine infectious anemia virus (EIAV) are also contemplated. In another embodiment, RetinoStat.RTM., an equine infectious anemia virus-based lentiviral gene therapy vector that expresses angiostatic proteins endostatin and angiostatin that is contemplated to be delivered via a subretinal injection. In another embodiment, use of self-inactivating lentiviral vectors is contemplated.

[0682] Any RNA of the systems, for example a guide RNA or a base editor-encoding mRNA, can be delivered in the form of RNA. Base editor-encoding mRNA can be generated using in vitro transcription. For example, nuclease mRNA can be synthesized using a PCR cassette containing the following elements: T7 promoter, optional kozak sequence (GCCACC), nuclease sequence, and 3′ UTR such as a 3′ UTR from beta globin-polyA tail. The cassette can be used for transcription by T7 polymerase. Guide polynucleotides (e.g., gRNA) can also be transcribed using in vitro transcription from a cassette containing a T7 promoter, followed by the sequence “GG”, and guide polynucleotide sequence.

[0683] To enhance expression and reduce possible toxicity, the base editor-coding sequence and/or the guide nucleic acid can be modified to include one or more modified nucleoside e.g. using pseudo-U or 5-Methyl-C.

[0684] The disclosure in some embodiments encompasses a method of modifying a cell or organism. The cell can be a prokaryotic cell or a eukaryotic cell. The cell can be a mammalian cell. The mammalian cell many be a non-human primate, bovine, porcine, rodent or mouse cell. The modification introduced to the cell by the base editors, compositions and methods of the present disclosure can be such that the cell and progeny of the cell are altered for improved production of biologic products such as an antibody, starch, alcohol or other desired cellular output. The modification introduced to the cell by the methods of the present disclosure can be such that the cell and progeny of the cell include an alteration that changes the biologic product produced.

[0685] The system can comprise one or more different vectors. In an aspect, the base editor is codon optimized for expression the desired cell type, preferentially a eukaryotic cell, preferably a mammalian cell or a human cell.

[0686] In general, codon optimization refers to a process of modifying a nucleic acid sequence for enhanced expression in the host cells of interest by replacing at least one codon (e.g. about or more than about 1, 2, 3, 4, 5, 10, 15, 20, 25, 50, or more codons) of the native sequence with codons that are more frequently or most frequently used in the genes of that host cell while maintaining the native amino acid sequence. Various species exhibit particular bias for certain codons of a particular amino acid. Codon bias (differences in codon usage between organisms) often correlates with the efficiency of translation of messenger RNA (mRNA), which is in turn believed to be dependent on, among other things, the properties of the codons being translated and the availability of particular transfer RNA (tRNA) molecules. The predominance of selected tRNAs in a cell is generally a reflection of the codons used most frequently in peptide synthesis. Accordingly, genes can be tailored for optimal gene expression in a given organism based on codon optimization. Codon usage tables are readily available, for example, at the “Codon Usage Database” available at www.kazusa.orjp/codon/ (visited Jul. 9, 2002), and these tables can be adapted in a number of ways. See, Nakamura, Y., et al. “Codon usage tabulated from the international DNA sequence databases: status for the year 2000” Nucl. Acids Res. 28:292 (2000). Computer algorithms for codon optimizing a particular sequence for expression in a particular host cell are also available, such as Gene Forge (Aptagen; Jacobus, Pa.), are also available. In some embodiments, one or more codons (e.g. 1, 2, 3, 4, 5, 10, 15, 20, 25, 50, or more, or all codons) in a sequence encoding an engineered nuclease correspond to the most frequently used codon for a particular amino acid.

[0687] Packaging cells are typically used to form virus particles that are capable of infecting a host cell. Such cells include 293 cells, which package adenovirus, and psi.2 cells or PA317 cells, which package retrovirus. Viral vectors used in gene therapy are usually generated by producing a cell line that packages a nucleic acid vector into a viral particle. The vectors typically contain the minimal viral sequences required for packaging and subsequent integration into a host, other viral sequences being replaced by an expression cassette for the polynucleotide(s) to be expressed. The missing viral functions are typically supplied in trans by the packaging cell line. For example, AAV vectors used in gene therapy typically only possess ITR sequences from the AAV genome which are required for packaging and integration into the host genome. Viral DNA can be packaged in a cell line, which contains a helper plasmid encoding the other AAV genes, namely rep and cap, but lacking ITR sequences. The cell line can also be infected with adenovirus as a helper. The helper virus can promote replication of the AAV vector and expression of AAV genes from the helper plasmid. The helper plasmid in some cases is not packaged in significant amounts due to a lack of ITR sequences. Contamination with adenovirus can be reduced by, e.g., heat treatment to which adenovirus is more sensitive than AAV.

Pharmaceutical Compositions

[0688] Other aspects of the present disclosure relate to pharmaceutical compositions comprising any of the base editors, fusion proteins, or the fusion protein-guide polynucleotide complexes described herein. The term “pharmaceutical composition”, as used herein, refers to a composition formulated for pharmaceutical use. In some embodiments, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier. In some embodiments, the pharmaceutical composition comprises additional agents (e.g., for specific delivery, increasing half-life, or other therapeutic compounds).

[0689] As used here, the term “pharmaceutically-acceptable carrier” means a pharmaceutically-acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, manufacturing aid (e.g., lubricant, talc magnesium, calcium or zinc stearate, or steric acid), or solvent encapsulating material, involved in carrying or transporting the compound from one site (e.g., the delivery site) of the body, to another site (e.g., organ, tissue or portion of the body). A pharmaceutically acceptable carrier is “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the tissue of the subject (e.g., physiologically compatible, sterile, physiologic pH, etc.).

[0690] Some nonlimiting examples of materials which can serve as pharmaceutically-acceptable carriers include: (1) sugars, such as lactose, glucose and sucrose; (2) starches, such as corn starch and potato starch; (3) cellulose, and its derivatives, such as sodium carboxymethyl cellulose, methylcellulose, ethyl cellulose, microcrystalline cellulose and cellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7) lubricating agents, such as magnesium stearate, sodium lauryl sulfate and talc; (8) excipients, such as cocoa butter and suppository waxes; (9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; (10) glycols, such as propylene glycol; (11) polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol (PEG); (12) esters, such as ethyl oleate and ethyl laurate; (13) agar; (14) buffering agents, such as magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer's solution; (19) ethyl alcohol; (20) pH buffered solutions; (21) polyesters, polycarbonates and/or polyanhydrides; (22) bulking agents, such as polypeptides and amino acids (23) serum alcohols, such as ethanol; and (23) other non-toxic compatible substances employed in pharmaceutical formulations. Wetting agents, coloring agents, release agents, coating agents, sweetening agents, flavoring agents, perfuming agents, preservative and antioxidants can also be present in the formulation. The terms such as “excipient,” “carrier,” “pharmaceutically acceptable carrier,” “vehicle,” or the like are used interchangeably herein.

[0691] Pharmaceutical compositions can comprise one or more pH buffering compounds to maintain the pH of the formulation at a predetermined level that reflects physiological pH, such as in the range of about 5.0 to about 8.0. The pH buffering compound used in the aqueous liquid formulation can be an amino acid or mixture of amino acids, such as histidine or a mixture of amino acids such as histidine and glycine. Alternatively, the pH buffering compound is preferably an agent which maintains the pH of the formulation at a predetermined level, such as in the range of about 5.0 to about 8.0, and which does not chelate calcium ions. Illustrative examples of such pH buffering compounds include, but are not limited to, imidazole and acetate ions. The pH buffering compound may be present in any amount suitable to maintain the pH of the formulation at a predetermined level.

[0692] Pharmaceutical compositions can also contain one or more osmotic modulating agents, i.e., a compound that modulates the osmotic properties (e.g, tonicity, osmolality, and/or osmotic pressure) of the formulation to a level that is acceptable to the blood stream and blood cells of recipient individuals. The osmotic modulating agent can be an agent that does not chelate calcium ions. The osmotic modulating agent can be any compound known or available to those skilled in the art that modulates the osmotic properties of the formulation. One skilled in the art may empirically determine the suitability of a given osmotic modulating agent for use in the inventive formulation. Illustrative examples of suitable types of osmotic modulating agents include, but are not limited to: salts, such as sodium chloride and sodium acetate; sugars, such as sucrose, dextrose, and mannitol; amino acids, such as glycine; and mixtures of one or more of these agents and/or types of agents. The osmotic modulating agent(s) may be present in any concentration sufficient to modulate the osmotic properties of the formulation.

[0693] In some embodiments, the pharmaceutical composition is formulated for delivery to a subject, e.g., for gene editing. Suitable routes of administrating the pharmaceutical composition described herein include, without limitation: topical, subcutaneous, transdermal, intradermal, intralesional, intraarticular, intraperitoneal, intravesical, transmucosal, gingival, intradental, intracochlear, transtympanic, intraorgan, epidural, intrathecal, intramuscular, intravenous, intravascular, intraosseus, periocular, intratumoral, intracerebral, and intracerebroventricular administration.

[0694] In some embodiments, the pharmaceutical composition described herein is administered locally to a diseased site (e.g., tumor site). In some embodiments, the pharmaceutical composition described herein is administered to a subject by injection, by means of a catheter, by means of a suppository, or by means of an implant, the implant being of a porous, non-porous, or gelatinous material, including a membrane, such as a sialastic membrane, or a fiber.

[0695] In other embodiments, the pharmaceutical composition described herein is delivered in a controlled release system. In one embodiment, a pump can be used (See, e.g., Langer, 1990, Science 249: 1527-1533; Sefton, 1989, CRC Crit. Ref. Biomed. Eng. 14:201; Buchwald et al., 1980, Surgery 88:507; Saudek et al., 1989, N. Engl. J. Med. 321:574). In another embodiment, polymeric materials can be used. (See, e.g., Medical Applications of Controlled Release (Langer and Wise eds., CRC Press, Boca Raton, Fla., 1974); Controlled Drug Bioavailability, Drug Product Design and Performance (Smolen and Ball eds., Wiley, New York, 1984); Ranger and Peppas, 1983, Macromol. Sci. Rev. Macromol. Chem. 23:61. See also Levy et al., 1985, Science 228: 190; During et al., 1989, Ann. Neurol. 25:351; Howard et ah, 1989, J. Neurosurg. 71: 105.) Other controlled release systems are discussed, for example, in Langer, supra.

[0696] In some embodiments, the pharmaceutical composition is formulated in accordance with routine procedures as a composition adapted for intravenous or subcutaneous administration to a subject, e.g., a human. In some embodiments, pharmaceutical composition for administration by injection are solutions in sterile isotonic use as solubilizing agent and a local anesthetic such as lignocaine to ease pain at the site of the injection. Generally, the ingredients are supplied either separately or mixed together in unit dosage form, for example, as a dry lyophilized powder or water free concentrate in a hermetically sealed container such as an ampoule or sachette indicating the quantity of active agent. Where the pharmaceutical is to be administered by infusion, it can be dispensed with an infusion bottle containing sterile pharmaceutical grade water or saline. Where the pharmaceutical composition is administered by injection, an ampoule of sterile water for injection or saline can be provided so that the ingredients can be mixed prior to administration.

[0697] A pharmaceutical composition for systemic administration can be a liquid, e.g., sterile saline, lactated Ringer's or Hank's solution. In addition, the pharmaceutical composition can be in solid forms and re-dissolved or suspended immediately prior to use. Lyophilized forms are also contemplated. The pharmaceutical composition can be contained within a lipid particle or vesicle, such as a liposome or microcrystal, which is also suitable for parenteral administration. The particles can be of any suitable structure, such as unilamellar or plurilamellar, so long as compositions are contained therein. Compounds can be entrapped in “stabilized plasmid-lipid particles” (SPLP) containing the fusogenic lipid dioleoylphosphatidylethanolamine (DOPE), low levels (5-10 mol %) of cationic lipid, and stabilized by a polyethyleneglycol (PEG) coating (Zhang Y. P. et ah, Gene Ther. 1999, 6: 1438-47). Positively charged lipids such as N-[1-(2,3-dioleoyloxi)propyl]-N,N,N-trimethyl-amoniummethylsulfate, or “DOTAP,” are particularly preferred for such particles and vesicles. The preparation of such lipid particles is well known. See, e.g., U.S. Pat. Nos. 4,880,635; 4,906,477; 4,911,928; 4,917,951; 4,920,016; and 4,921,757; each of which is incorporated herein by reference.

[0698] The pharmaceutical composition described herein can be administered or packaged as a unit dose, for example. The term “unit dose” when used in reference to a pharmaceutical composition of the present disclosure refers to physically discrete units suitable as unitary dosage for the subject, each unit containing a predetermined quantity of active material calculated to produce the desired therapeutic effect in association with the required diluent; i.e., carrier, or vehicle.

[0699] Further, the pharmaceutical composition can be provided as a pharmaceutical kit comprising (a) a container containing a compound of the invention in lyophilized form and (b) a second container containing a pharmaceutically acceptable diluent (e.g., sterile used for reconstitution or dilution of the lyophilized compound of the invention. Optionally associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration.

[0700] In another aspect, an article of manufacture containing materials useful for the treatment of the diseases described above is included. In some embodiments, the article of manufacture comprises a container and a label. Suitable containers include, for example, bottles, vials, syringes, and test tubes. The containers can be formed from a variety of materials such as glass or plastic. In some embodiments, the container holds a composition that is effective for treating a disease described herein and can have a sterile access port. For example, the container can be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle. The active agent in the composition is a compound of the invention. In some embodiments, the label on or associated with the container indicates that the composition is used for treating the disease of choice. The article of manufacture can further comprise a second container comprising a pharmaceutically-acceptable buffer, such as phosphate-buffered saline, Ringer's solution, or dextrose solution. It can further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, syringes, and package inserts with instructions for use.

[0701] In some embodiments, any of the fusion proteins, gRNAs, and/or complexes described herein are provided as part of a pharmaceutical composition. In some embodiments, the pharmaceutical composition comprises any of the fusion proteins provided herein. In some embodiments, the pharmaceutical composition comprises any of the complexes provided herein. In some embodiments, the pharmaceutical composition comprises a ribonucleoprotein complex comprising an RNA-guided nuclease (e.g., Cas9) that forms a complex with a gRNA and a cationic lipid. In some embodiments pharmaceutical composition comprises a gRNA, a nucleic acid programmable DNA binding protein, a cationic lipid, and a pharmaceutically acceptable excipient. Pharmaceutical compositions can optionally comprise one or more additional therapeutically active substances.

Methods of Treating SDS

[0702] Provided also are methods of treating SDS and/or the genetic mutations associated with a SBDS gene conversion, or SBDSP that causes SDS. The methods comprise administering to a subject (e.g., a mammal, such as a human) a therapeutically effective amount of a pharmaceutical composition that comprises a polynucleotide encoding a base editor system (e.g., base editor and gRNA) described herein. In some embodiments, the base editor comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain or a cytidine deaminase domain. In some embodiments, the base editor comprises a composition comprising a polynucleotide programmable DNA binding domain and an adenosine deaminase domain or a cytidine deaminase domain. In an embodiment, the base editor comprises a polynucleotide programmable DNA binding domain and a cytidine deaminase domain. In an embodiment, the base editor comprises a composition comprising a polynucleotide programmable DNA binding domain and a cytidine deaminase domain. In some embodiments, the base editor is a fusion protein that comprises a polynucleotide programmable DNA binding domain and an adenosine deaminase domain or a cytidine deaminase domain. A cell of the subject is transduced with the base editor and one or more guide polynucleotides that target the base editor to effect an A⋅T to G⋅C alteration (if the cell is transduced with an adenosine deaminase domain) or a C⋅G to UA alteration (if the cell is transduced with a cytidine deaminase domain) of a nucleic acid sequence containing one or more mutations in the SBDS (e.g., a SBDSP) gene.

[0703] The methods herein include administering to the subject (including a subject identified as being in need of such treatment, or a subject suspected of being at risk of disease and in need of such treatment) an effective amount of a composition described herein. Identifying a subject in need of such treatment can be in the judgment of a subject or a health care professional and can be subjective (e.g. opinion) or objective (e.g. measurable by a test or diagnostic method).

[0704] The therapeutic methods, in general, comprise administration of a therapeutically effective amount of a pharmaceutical composition comprising, for example, a vector encoding a base editor and a gRNA that targets the SBDS or SBDSP gene of a subject (e.g., a human patient) in need thereof. Such treatment will be suitably administered to a subject, particularly a human subject, suffering from, having, susceptible to, or at risk for SDS. The compositions herein may be also used in the treatment of any other disorders in which a mutation in SBDS or a gene encoding SBDS may be implicated.

[0705] In one embodiment, a method of monitoring treatment progress is provided. The method includes the step of determining a level of diagnostic marker (Marker) (e.g., SNP associated with SDS) or diagnostic measurement (e.g., screen, assay) in a subject suffering from or susceptible to a disorder or symptoms thereof associated with SDS in which the subject has been administered a therapeutic amount of a composition herein sufficient to treat the disease or symptoms thereof. The level of Marker determined in the method can be compared to known levels of Marker in either healthy normal controls or in other afflicted patients to establish the subject's disease status. In preferred embodiments, a second level of Marker in the subject is determined at a time point later than the determination of the first level, and the two levels are compared to monitor the course of disease or the efficacy of the therapy. In certain preferred embodiments, a pre-treatment level of Marker in the subject is determined prior to beginning treatment according to this invention; this pre-treatment level of Marker can then be compared to the level of Marker in the subject after the treatment commences, to determine the efficacy of the treatment.

[0706] In some embodiments, compositions provided herein are administered to a subject, for example, to a human subject, in order to effect a targeted genomic modification within the subject. In some embodiments, cells are obtained from the subject and contacted with any of the pharmaceutical compositions provided herein. In some embodiments, cells removed from a subject and contacted ex vivo with a pharmaceutical composition are re-introduced into the subject, optionally after the desired genomic modification has been effected or detected in the cells. Methods of delivering pharmaceutical compositions comprising nucleases are known, and are described, for example, in U.S. Pat. Nos. 6,453,242; 6,503,717; 6,534,261; 6,599,692; 6,607,882; 6,689,558; 6,824,978; 6,933,113; 6,979,539; 7,013,219; and 7,163,824, the disclosures of all of which are incorporated by reference herein in their entireties. Although the descriptions of pharmaceutical compositions provided herein are principally directed to pharmaceutical compositions which are suitable for administration to humans, it will be understood by the skilled artisan that such compositions are generally suitable for administration to animals or organisms of all sorts, for example, for veterinary use.

[0707] Modification of pharmaceutical compositions suitable for administration to humans in order to render the compositions suitable for administration to various animals is well understood, and the ordinarily skilled veterinary pharmacologist can design and/or perform such modification with merely ordinary, if any, experimentation. Subjects to which administration of the pharmaceutical compositions is contemplated include, but are not limited to, humans and/or other primates; mammals, domesticated animals, pets, and commercially relevant mammals such as cattle, pigs, horses, sheep, cats, dogs, mice, and/or rats; and/or birds, including commercially relevant birds such as chickens, ducks, geese, and/or turkeys.

[0708] Formulations of the pharmaceutical compositions described herein can be prepared by any method known or hereafter developed in the art of pharmacology. In general, such preparatory methods include the step of bringing the active ingredient(s) into association with an excipient and/or one or more other accessory ingredients, and then, if necessary and/or desirable, shaping and/or packaging the product into a desired single- or multi-dose unit. Pharmaceutical formulations can additionally comprise a pharmaceutically acceptable excipient, which, as used herein, includes any and all solvents, dispersion media, diluents, or other liquid vehicles, dispersion or suspension aids, surface active agents, isotonic agents, thickening or emulsifying agents, preservatives, solid binders, lubricants and the like, as suited to the particular dosage form desired. Remington's The Science and Practice of Pharmacy, 21st Edition, A. R. Gennaro (Lippincott, Williams & Wilkins, Baltimore, Md., 2006; incorporated in its entirety herein by reference) discloses various excipients used in formulating pharmaceutical compositions and known techniques for the preparation thereof. See also PCT application PCT/US2010/055131 (Publication number WO2011/053982 A8, filed Nov. 2, 2010), incorporated in its entirety herein by reference, for additional suitable methods, reagents, excipients and solvents for producing pharmaceutical compositions comprising a nuclease.

[0709] Except insofar as any conventional excipient medium is incompatible with a substance or its derivatives, such as by producing any undesirable biological effect or otherwise interacting in a deleterious manner with any other component(s) of the pharmaceutical composition, its use is contemplated to be within the scope of this disclosure.

[0710] The compositions, as described above, can be administered in effective amounts. The effective amount will depend upon the mode of administration, the particular condition being treated, and the desired outcome. It may also depend upon the stage of the condition, the age and physical condition of the subject, the nature of concurrent therapy, if any, and like factors well-known to the medical practitioner. For therapeutic applications, it is that amount sufficient to achieve a medically desirable result.

Kits

[0711] Various aspects of this disclosure provide kits comprising a base editor system. In one embodiment, the kit comprises a nucleic acid construct comprising a nucleotide sequence encoding a nucleobase editor fusion protein. The fusion protein comprises a deaminase (e.g., cytidine deaminase or adenine deaminase) and a nucleic acid programmable DNA binding protein (napDNAbp). In some embodiments, the kit comprises at least one guide RNA capable of targeting a nucleic acid molecule of interest, e.g., SDS-associated mutations. In some embodiments, the kit comprises a nucleic acid construct comprising a nucleotide sequence encoding at least one guide RNA.

[0712] The kit provides, in some embodiments, instructions for using the kit to edit one or more SDS-associated mutations. The instructions will generally include information about the use of the kit for editing nucleic acid molecules. In other embodiments, the instructions include at least one of the following: precautions; warnings; clinical studies; and/or references. The instructions may be printed directly on the container (when present), or as a label applied to the container, or as a separate sheet, pamphlet, card, or folder supplied in or with the container. In a further embodiment, a kit can comprise instructions in the form of a label or separate insert (package insert) for suitable operational parameters. In yet another embodiment, the kit can comprise one or more containers with appropriate positive and negative controls or control samples, to be used as standard(s) for detection, calibration, or normalization. The kit can further comprise a second container comprising a pharmaceutically-acceptable buffer, such as (sterile) phosphate-buffered saline, Ringer's solution, or dextrose solution. It can further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, syringes, and package inserts with instructions for use.

[0713] In certain embodiments, the kit is useful for the treatment of a subject having Shwachman Diamond Syndrome (SDS).

EXAMPLES

[0714] The following examples are provided for illustrative purposes only and are not intended to limit the scope of the claims provided herein.

Example 1 PAM Variant Validation in Base Editors

[0715] Novel CRISPR systems and PAM variants enable base editors (e.g., PV1-PV28) to edit mutations (e.g., gene conversions that disrupt splicing) present in an SBDS polynucleotide (e.g., SBDSP polynucleotide). Several novel PAM variants have been evaluated and validated. Details of PAM evaluations and base editors are described, for example, in International PCT Application Nos. PCT/2017/045381 (WO2018/027078) and PCT/US2016/058344 (WO2017/070632), each of which is incorporated herein by reference in its entirety. Also see Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N. M., et al., “Programmable base editing of A⋅T to G⋅C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); and Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017), the entire contents of each of which are hereby incorporated by reference.

Example 2 Gene Editing to Correct Aberrant Splicing Associated with Shwachman Diamond Syndrome (SDS)

[0716] Mutations associated with SDS include a TA.fwdarw.CT dinucleotide change at position 183-184 and a 258+2T.fwdarw.C change (FIGS. 1A and 1B). The mutation 258+2T.fwdarw.C is predicted to disrupt the donor splice site of intron 2, and the observed 8-bp deletion is consistent with use of an upstream cryptic splice donor site at position 251-252. The dinucleotide alteration 183-184TA.fwdarw.CT introduces an in-frame stop codon (K62X), and 258+2T.fwdarw.C and the resultant 8-bp deletion cause premature truncation of the encoded protein by frameshift (84Cfs3).

[0717] Pathogenic mutations in the SBDS gene that result in aberrant splicing are associated with Shwachman Diamond Syndrome. As shown in FIG. 2A and FIG. 2B, aberrant splicing mutations are corrected using a base editor having adenosine deaminase or cytidine deaminase activity and the requisite PAM specificity, using the gRNAs at Table 11.

TABLE-US-00090 TABLE 11 Guide RNAs for Editing Pathogenic SBDS Guide RNA Sequence and (Editor) Location/Mutation PAM 5′-GUAAGCAGGCGGGUAACAGC-3′ rs113993993 258 + 2T > C NGC (CBE) 5′-AGCAGGCGGGUAACAGCUGC-3′ rs113993993 258 + 2T > C NGC (CBE) 5′-GCGGGUAACAGCUGCAGCAU-3′ rs113993993 258 + 2T > C NGC (CBE) 5′-UGUAAAUGUUUCCUAAGGUC-3′ 183-184TA > CT Rs113993991 NGC (ABE) 5′-AAUGUUUCCUAAGGUCAGGU-3′ 183-184TA > CT Rs113993991 NGG (ABE)

[0718] A 183-184TA>CT Rs113993991 results in a stop codon (TAA), which is shown in FIG. 2A. An ABE selected from among PV1-14 is used to introduce convert TAA to TGG, which encodes Tryptophan. Such conversion would permit transcription of a protein having a Trp (W) in place of a Lys (K) at amino acid position 62.

[0719] Base Editors (PV1-14) are used in conjunction with the gRNAs depicted in FIG. 2A to edit an SBDS gene comprising an alteration (e.g., gene conversion). Editors PV 1-14 are used to edit an SBDS gene using a guide RNA having any of the following sequences:

TABLE-US-00091 5′-UGUAAAUGUUUCCUAAGGUC-3′ 5′-AAUGUUUCCUAAGGUCAGGU-3′.

[0720] A description of the editors (PV1-14) useful for correction of SDS-associated mutations (e.g., gene conversion) follows:

TABLE-US-00092 PV1. pCMV_monoABE8.1_bpNLS + Y147T MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCTFFRMPRQVFNAQKKAQSSTD PV2. pCMV_monoABE8.1_bpNLS + Y147R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCRFFRMPRQVFNAQKKAQSSTD PV3 pCMV_monoABE8.1_bpNLS + Q154S MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRSVFNAQKKAQSSTD PV4 pCMV_monoABE8.1_bpNLS + Y123H MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHHP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD PV5 pCMV_monoABE8.1_bpNLS + V82S MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDAILYSTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSTD PV6 pCMV_monoABE8.1_bpNLS + T166R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRQVFNAQKKAQSSRD PV7 (pCMV_monoABE8.1_bpNLS + Q154R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRRVFNAQKKAQSSTD PV8 pCMV_monoABE8.1_bpNLS + Y147R_Q154R_Y123H MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHHP GMNHRVEITEGILADECAALLCRFFRMPRRVFNAQKKAQSSTD PV9 pCMV_monoABE8.1_bpNLS + Y147R_Q154R_I76Y MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLYDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCRFFRMPRRVFNAQKKAQSSTD PV10 pCMV_monoABE8.1_bpNLS + Y147R_Q154R_T166R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCRFFRMPRRVFNAQKKAQSSRD PV11 pCMV_monoABE8.1_bpNLS + Y147T_Q154R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCTFFRMPRRVFNAQKKAQSSTD PV12 pCMV_monoABE8.1_bpNLS + Y147T_Q154S MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCTFFRMPRSVFNAQKKAQSSTD PV13 pCMV_monoABE8.1_bpNLS + H123Y123H_Y147R_Q154R_176Y MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLYDATLYVTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHHP GMNHRVEITEGILADECAALLCRFFRMPRRVFNAQKKAQSSTD PV14 pCMV_monoABE8.1_bpNLS + V82S + Q154R MSEVEFSHEYWMRHALTLAKRARDEREVPVGAVLVLNNRVIGEGWNRAIGLHDPTAHAEIMA LRQGGLVMQNYRLIDAILYSTFEPCVMCAGAMIHSRIGRVVFGVRNAKTGAAGSLMDVLHYP GMNHRVEITEGILADECAALLCYFFRMPRRVFNAQKKAQSSTD

[0721] A guide RNA (gRNA) selected from among the following is used to target a rs113993993 258+2T>C. As shown in FIG. 2B, the following gRNA sequences are used in conjunction with a cytidine base editor to deaminate the cytosine present in the splice site, which is converted to thymidine, thereby restoring splicing:

TABLE-US-00093 5′-GUAAGCAGGCGGGUAACAGC-3′ 5′-AGCAGGCGGGUAACAGCUGC-3′ 5′-GCGGGUAACAGCUGCAGCAU-3′

[0722] In one embodiment, the cytidine base editor is BE4 or comprises APOBEC or AID. A modified SpCas9 including amino acid substitutions D1135M, S1136Q, G1218K, E1219F, A1322R, D1332A, R1335E, and T1337R and having specificity for the altered PAM 5′-NGC-3′ is used for correction of mutations associated with SDS. A wild-type SpCas9 having specificity for altered PAM 5′-NGG-3″ may be used in some embodiments.

[0723] Other pathogenic mutations affecting splicing are corrected using strategies similar to those illustrated in FIGS. 2A and 2B.

Example 3 Cytidine Base Editors (CBEs) Having High On-Target Editing Activity to Treat SDS

[0724] As noted supra, Shwachman-Diamond Syndrome (SDS) is a disease inherited in an autosomal recessive pattern, characterized by bone marrow failure and clinically significant hematopoietic abnormalities. SDS has an incidence in the population of 1/77,000 (Compound Heterozygous) and results from point mutations (SNPs) in the SBDS gene that result in deficient RNA processing. SDS patients are at a higher risk of hematopoietic stem cell therapy (HSCT) rejection. One-third of patients have chronic neutropenia; myelodysplastic Syndrome (MDS) and acute leukemia occur in up to one third of patients. To date, clinical phenotype and treatment are highly variable and patient-specific. Treatments and medical interventions for SDS patients include red cell transfusions, management of recurrent and serious infections, bone marrow transplants and associated management.

[0725] A solution to providing a therapeutic treatment for SDS by employing base editing to restore correct splicing by targeting a SNP associated with SDS disease, e.g., as described herein. Experiments further to those described in Example 2 were performed using cytidine base editors (CBEs) that were developed to target a common splice site SNP in the SBDS gene for precise correction of the mutation. In particular, a mutation targeted in SBDS is rs113993993 C.fwdarw.T. (FIG. 2C and FIGS. 2B and 2D). In an embodiment, HSCT involving autologous CD34+ cells may be used in conjunction with CBE base editing to restore correct splicing by targeting the SNP mutation in the SBDS gene.

[0726] New base editors were produced and assessed for targeting a splice site SNP (e.g., SNP rs113993993 258+2T>C) in the SBDS gene (FIGS. 2A-2D). The base editors were cytidine base editors that comprised a cytidine deaminase component and a Cas9 component containing a combination of mutations in the Cas9 amino acid sequence (relative to a non-mutated, wildtype Cas9 (e.g., SpCas9) polypeptide sequence) that confer the ability of Cas9 to bind to a noncanonical PAM sequence, i.e. an NGC PAM or an NGC-containing PAM, e.g., NGCC, NGCT, NGCG, in a target polynucleotide (DNA) sequence (or target gene). Cas9 proteins containing the described combination of mutations are termed “Cas9 variants.” The cytidine base editors comprising a cytidine deaminase and a Cas9 variant are termed “NGC CBE variants” herein.

[0727] FIGS. 3A-3C show the amino acid positions in the Cas9 polypeptide sequence in which amino acid substitutions occur to produce the modified Cas9 variants, such as modified SpCas9, which have specificity for the altered PAM 5′-NGC-3′. By way of particular yet nonlimiting example, a modified Cas9 (SpCas9) variant polypeptide, termed “224” in FIGS. 3A-3C, includes the following combination of amino acid sequences/substitutions D1135M, 51136Q, G1218K, E1219F, A1322R, D1332, R1335E, and T1337R; a modified Cas9 (SpCas9) variant polypeptide, termed “225” in FIGS. 3A-3C, includes the following combination of amino acid sequences/substitutions D1135M, 51136Q, G1218K, E1219F, A1322R, D1332A, R1335E, and T1337R; a modified Cas9 (SpCas9) variant polypeptide, termed “226” in FIGS. 3A-3C, includes amino acid substitutions D1135M, 51136Q, G1218K, E1219F, A1322R, D1332K, R1335E, and 11337R; a modified Cas9 (SpCas9) variant polypeptide, termed “227” in FIGS. 3A-3C, includes amino acid substitutions D1135M, 51136Q, G1218K, E1219F, A1322R, D1332A, R1335E, and T1337Q; a modified Cas9 (SpCas9) variant polypeptide, termed “230” in FIGS. 3A-3C, includes amino acid substitutions D1135M, 51136Q, G1218K, E1219F, A1322R, D1332A, R1335Q, and T1337Q; a modified Cas9 (SpCas9) variant polypeptide, termed “235” in FIGS. 3A-3C, includes amino acid substitutions D1135M, 51136Q, G1218K, E1219F, A1322R, D1332A, R1335D, and T1337Q; a modified Cas9 (SpCas9) variant polypeptide, termed “237” in FIGS. 3A-3C, includes amino acid substitutions D1135Q, S1136, G1218T, E1219W, A1322R, D1332, R1335N, and T1337; a modified Cas9 (SpCas9) variant polypeptide, termed “242” in FIGS. 3A-3C, includes amino acid substitutions D1135H, S1136, G1218S, E1219W, A1322R, D1332, R1335V, and T1337; a modified Cas9 (SpCas9) variant polypeptide, termed “244” in FIGS. 3A-3C, includes amino acid substitutions D1135C, S1136W, G1218N, E1219W, A1322R, D1332, R1335N, and T1337; a modified Cas9 (SpCas9) variant polypeptide, termed “245” in FIGS. 3A-3C, includes amino acid substitutions D113LM, S1136W, G1218R, E1219S, A1322R, D1332, R1335E, and T1337; a modified Cas9 (SpCas9) variant polypeptide, termed “259” in FIGS. 3A-3C, includes amino acid substitutions D1135G, S1136W, G1218S, E1219M, A1322R, D1332, R1335Q, and T1337R; a modified Cas9 (SpCas9) variant polypeptide, termed “Nureki” in FIGS. 3A-3C, includes amino acid substitutions L111R, D1135V, 51136Q, G1218K, E1219F, A1322R, D1332, R1335A, and T1337R; a modified Cas9 (SpCas9) variant polypeptide, termed “NGC Rd1” in FIGS. 3A-3C, includes amino acid substitutions D1135M, S1136, 51216G, G1218, E1219, A1322, D1332A, R1335Q, and T1337; and a modified Cas9 (SpCas9) variant polypeptide, termed “267 (NGC Rd2)” in FIGS. 3A-3C, includes amino acid substitutions D1135G, S1136, 51216G, G1218, E1219, A1322R, D1332A, R1335E, and T1337R have specificity for the altered PAM 5′-NGC-3′ (or the PAM comprising 5′-NGC-3′) and are used for correction of mutations associated with SDS. These Cas9 variants, as well as others shown in FIGS. 3A-3C, are encoded by polynucleotides contained in plasmids having the same terminology, e.g., PV225, PV226, and PV230, respectively. The plasmids are utilized in cell-based (e.g., HEK293 cells), in vitro assays to assess the base editing efficiency of the NGC CBE base editors that target the mutated SNP in the SBDS gene. As would be appreciated by one having skill in the art, such plasmids (plasmid vectors) comprise a suitable promoter, e.g., a CMV promoter, and operably linked polynucleotide sequences encoding the cytidine deaminase and nuclease, e.g., Cas9 (SpCas9) variant, components. In some cases, all or a relevant portion of the SBDS polynucleotide sequence containing the target polynucleotide sequence may be contained in the plasmid, or may be contained in a separate plasmid. In some embodiments, virus vector(s) containing a suitable promoter sequence and the polynucleotide sequences of the CBE components and/or all or a relevant portion of the SBDS polynucleotide sequence are used. In an embodiment, the vector is a lentivirus vector. In some cases, the HEK293 cells are transfected with a vector, e.g., a lentivirus vector, that harbors all or a relevant portion of the SBDS polynucleotide sequence that contains the target splice site SNP.

[0728] The cytidine deaminase component of the variant NGC CBEs described herein include, without limitation, the cytidine deaminase BE4, or BE4 in which the APOBEC1 sequence is replaced with another APOBEC cytidine deaminase sequence as described herein; or various APOBEC cytidine deaminases as described supra and infra. The cytidine deaminases rAPOBEC1, BE4-rAPOBEC1, PpAPOBEC1, BE4-PpABOBEC1, PpAPOBEC1 containing an H122A substitution, BE4-PpAPOBEC1 containing an H122A substitution; BE4-RrA3F containing an F130L substitution; BE4-AmAPOBEC1; and BE4-SsAPOBEC2 provide base editing activity when used in conjunction with a Cas9 variant and a guide RNA as described herein. The relative mutation rate of CBEs containing different, representative cytidine deaminases is shown in FIG. 4.

[0729] Guide RNAs (gRNAs) and target gRNAs used in conjunction with the NGC CBE variants to target the SBDS target polynucleotide sequence containing the splice site SNP (SNP rs113993993 258+2T>C) and restore correct splicing are shown in FIG. 5 and in Table 12 below.

TABLE-US-00094 TABLE 12 gRNAs used with NGC CBE variants Guide RNA Number gRNA PAM  43 5′-GUAAGCAGGCGGGUAACAGC-3′ NGC  44 5′-AGCAGGCGGGUAACAGCUGC-3′ NGC  45 5′-GCGGGUAACAGCTGCAGCAU-3′ NGC  88 5′-GCAGGCGGGUAACAGCUGC-3′ NGC 199 5′-CAGGCGGGUAACAGCUGC-3′ AGC 200 5′-AGGCGGGUAACAGCUGC-3′ AGC 201 5′-AAGCAGGCGGGUAACAGCUGC-3′ AGC
The scaffold sequence for the gRNAs used in the studies described herein is as follows:

TABLE-US-00095 GUUUUAGAGC UAGAAAUAGC AAGUUAAAAU AAGGCUAGUC CGUUAUCAAC UUGAAAAAGU GGCACCGAGU CGGUGCUUUU (UUU).

[0730] By way of example, the 19mer gRNA (G88) and the 20mer gRNA (G44) used in conjunction with the NGC CBE variants as described herein, e.g., cytidine deaminase, BE4, and the Cas9 variants 226 and 230, showed a high percentage of on-target editing and a limited percentage of bystander edits, as well as a high degree of C.fwdarw.T on target editing. (FIGS. 6A and 6B). FIG. 6C shows that the 20mer gRNA (G44) used in conjunction with CBEs comprising a cytidine deaminase, e.g., BE4, and a number of different Cas9 variants (e.g., SpCas9 variants) in CBEs demonstrated a high percentage of on-target base editing and a low percentage of bystander (non-specific) editing. The target sequence and SNP site are represented by a bold “C” at position 7 of the sequence; the “C” at position 3 of the sequence represents a bystander nucleotide in the target sequence. The plasmid encoding the CBE comprising the SpCas9 variant termed “226” (FIGS. 3A-3C) is designated “PV226” in the figure.

[0731] The NGC CBE variants as described herein optimally exhibited a high percentage of on-target editing to restore corrective splicing, while concomitantly exhibiting low or limited bystander editing and/or off-target editing activity. As will be appreciated by the skilled artisan, a limited bystander editing activity exhibited by a cytidine base editor as described herein refers to a low percentage or limited activity of nucleobase editing within the base editing window.

Example 4 NGC Cytidine Base Editors (CBEs) Generated for High On-Target Editing Activity to Treat SDS

[0732] Additional cytidine base editors were generated comprising the NGC PAM interacting Cas9 variants described herein, such as 225, 226 and 244 having the sequences shown in FIGS. 3A-3C, in conjunction with several different cytidine deaminases. Plasmids encoding the Cas9 variants 225, 226 and 244, i.e., PV225, and PV244, respectively, were generated. In addition, plasmids containing polynucleotides encoding both a Cas9 variant and a cytidine deaminase, either together or separately, were constructed. Table 13 below shows the NGC CBEs (comprising a Cas9 variant and a cytidine deaminase polypeptide) that were created and used in studies to assess their ability to target the rs113993993 C.fwdarw.T mutation in the SBDS gene and to restore correct splicing.

TABLE-US-00096 TABLE 13 CBE (or Plasmid) CBE components- name Cas9_Cytidine Deaminase 447 PV-225_AmAPOBEC1 448 PV225_PmCDA1 449 PV225_PpAPOBEC1 H122A 450 PV225_RRA3F 451 PV225_SsAPOBEC2 452 PV226_AmpAPOBEC1 453 PV226_PmCDA1 454 PV226_PpAPOBEC1 H122A 455 PV226_RRA3F 456 PV226_SsAPOBEC2 457 PV244_AmAPOBEC1 458 PV244_PmCDA1 459 PV244_PpAPOBEC1 H122A 460 PV244_RRA3F 461 PV244_SsAPOBEC2

[0733] The NGC CBEs (cytidine base editors containing a cytidine deaminase and a Cas9 variant (e.g., an SpCas9 variant) containing a combination of amino acid mutations which provide the Cas9 protein with the ability to bind a PAM comprising NGC), together with one or more gRNAs, in particular, a 19mer and a 20mer gRNA such as G88 and G44, respectively, were assayed in HEK293 cells harboring the SBDS gene for on-target base editing of the SNP mutation in the SBDS gene. FIGS. 7A and 7B show the percent base editing activities of the various NGC CBEs described in Table 13 used together with the 19mer and 20mer gRNAs, e.g., G88 and G44. Further experiments were conducted with CBEs comprised of the cytidine deaminase PpAPOBEC1 and Cas9 variants 225, 454 and 459 having the specific combinations of mutations in the Cas9 sequences as presented in FIGS. 3A-3C, together with either the 19mer or the 20mer gRNAs to determine percentage editing/on-target and bystander editing activities in cell-based (HEK293) assays to correct the splice site SNP in the SBDS polynucleotide sequence (FIGS. 8A and 8B). As shown in FIGS. 8A and 8B, high on-target editing was exhibited by NGC CBEs 454 and 459 (Table 13) containing the PpAPOBEC1 cytodine deaminase and the Cas9 variants 226 and 244 (FIGS. 3A-3C), respectively. FIGS. 8C and 8D show the on-target and bystander base editing percentages of an NGC CBE comprising the AmAPOBEC1 cytidine deaminase and the Cas9 variants 225, 226 and 244 (FIGS. 3A-3C) together with either the 19mer (Guide 88) or the 20mer (Guide 44) gRNA in cell-based (HEK293) assays to correct the splice site SNP in the SBDS polynucleotide sequence. FIGS. 8E and 8F show the on-target and bystander base editing percentages of an NGC CBE comprising the PmCDA1 cytidine deaminase and the Cas9 variants 225, 453 and 458 (Table 13) together with either the 19mer (Guide 88) or the 20mer (Guide 44) gRNA in cell-based (HEK293) assays to correct the splice site SNP in the SBDS polynucleotide sequence. FIGS. 8G and 8H show the on-target and bystander base editing percentages of an NGC CBE comprising the RRA3F cytidine deaminase and the Cas9 variants 225, 455 and 460 (Table 13) together with either the 19mer (Guide 88) or the 20mer (Guide 44) gRNA in cell-based (HEK293) assays to correct the splice site SNP in the SBDS polynucleotide sequence. FIGS. 81 and 8J show the on-target and bystander base editing percentages of an NGC CBE comprising the SsAPOBEC2 cytidine deaminase and the Cas9 variants 225, 456 and 461 (Table 13) together with either the 19mer (Guide 88) or the 20mer (Guide 44) gRNA in cell-based (HEK293) assays to correct the splice site SNP in the SBDS polynucleotide sequence. In FIGS. 8A-8J, Cas9 variant 225 (or PV225) is alternatively termed “Beam shuffle.”

[0734] In further studies, additional amino acid mutations were created in the cytidine deaminase polypeptide, e.g., an H122A mutation in the PpAPOBEC1 polypeptide sequence, to determine if higher on-target base editing of the splice site SNP in the SBDS gene and correction of the splice site occurred. In addition to the H122A mutation alone, the H122A mutation and amino acid mutations R33A, W90F, K34A, R52A, H121A and Y120F were also made in the PpAPOBEC1 amino acid sequence to produce NGC CBEs for determining base editing efficiency (i.e., percentage of on-target editing versus bystander editing). The further mutated NGC CBE variants together with 19mer or 20mer gRNAs were tested in in vitro cell-based assays. As shown in FIGS. 9A and 9B, with either the 19mer or the 20mer gRNA, the additional mutations made in the PpAPOBEC1 cytidine deaminase polypeptide did not result in significantly increased base editing efficiency by the NGC CBEs containing them. FIGS. 9C and 9D present the data shown in FIGS. 9A and 9B, respectively, in dot blot format.

Example 5 Other NGC Cytidine Base Editors (CBEs) Containing SpCas9 Variants Having Activity on 5′-NGC-3′ PAMs to Treat SDS

[0735] To obtain and assess other NGC cytidine base editors containing SpCas9 variants having activity on 5′-NGC-3′ PAMs for use in treating SDS, additional SpCas9 variants with further mutations were produced. These NGC CBEs containing SpCas9 variants (PV225 and PV244 (FIGS. 3A-3C) and containing other amino acid substitutions) were termed “NRCH” editor variants, as the amino acid substitutions contained in these SpCas9 variants were similar to those described for SpCas9 variants capable of recognizing “NRCH” PAMs, where R=A or G, and H=A, C, or T (i.e., NRCH SpCas9), as described by S. Miller et al., April, 2020, “Continuous evolution of SpCas9 variants compatible with non-G PAMs,” Nature Biotechnology, 38(4):471-481 (published online 2020 Feb. 10. doi: 10.1038/s41587-020-0412-8), the contents of which are incorporated by reference herein in their entirety. As described by Miller et al., cytidine base editors containing a cytidine deaminase and a NRCH SpCas9 variant had a distinctly evolved preference for a C nucleobase at the third position in the PAM.

[0736] FIG. 10 presents a table depicting the mutations and combinations of mutations that were made in the SpCas9 protein to create NRCH-based SpCas9 variants. Combinations of the NRCH mutations as shown in FIG. 10 were included in several different SpCas9 variants to determine the combination of mutations that would be most beneficial for the SpCas9 variant component in the NGC CBEs used for correcting the splice site SNP in the SBDS gene associated with SDS. In a particular example, NGC CBEs containing a given cytidine deaminase, e.g., PpAPOBEC1 and the like, and an SpCas9 variant comprising certain mutations (FIGS. 3A-3C), together with combinations of NRCH mutations as described in Miller et al., supra, and exemplified below, may provide high percentages of on target editing and low percentages of bystander edits. In particular embodiments, the SpCas9 variants having the best ability to bind NGC PAM mutations may be combined with the PpAPOBEC H122A cytidine deaminase to identify those CBEs that demonstrate high on-target base editing compared with bystander effects. In related embodiments, an NGC CBE plasmid or viral vector construct comprising a polynucleotide encoding a SpCas9 variant, e.g., as shown in FIGS. 3A-3C, Table 13, or FIG. 10, having demonstrated ability to bind an NGC PAM and a cytidine deaminase, e.g., PpAPOBEC H122A, are encompassed to evaluate optimal combinations that provide the highest on target and lowest bystander editing in cell-based systems as described herein.

[0737] By way of particular example, the additional amino acid substitutions in 225 and 244 SpCas9 variants included one or more of A10T, I322V, S4091, E427G, R645L, R753G, R1114G, Q1221H, Y1336, 51338T, and H1349R (e.g., NRCH mutations in SpCas9). The on-target and bystander nucleobase editing by NGC CBEs containing NRCH SpCas9 variants and a cytidine deaminase, together with the 19mer or 20mer gRNAs as used in the experiments described in the Examples above, were assessed in cell-based (HEK293) assays to evaluate correction of the splice site SNP in the SBDS polynucleotide sequence (FIGS. 11A and 11B). As observed in FIGS. 11A and 11B, base editors 468 and 469 (Table 10) exhibited a high percentage of on-target base editing when used in conjunction with either the 19mer or the 20mer gRNA.

Example 6 mRNAs Encoding and Delivering NGC CBEs

[0738] Representative NGC CBE editors were cloned to produce mRNAs encoding these base editors. mRNA encoding the base editors is an optimal delivery system to achieve base editing in target DNA, e.g., the SBDS gene, in cells, and is also particularly suitable for therapeutic use in the clinic. As would be appreciated by the skilled practitioner, mRNA may shift the editing window and increase the efficiency of editing. Base editors having a higher percentage of C.fwdarw.T transitions and low or limited percentages of C.fwdarw.A or C.fwdarw.G transitions are especially useful and suitable for mRNA delivery. Therefore, mRNA encoding several of the NGC CBEs that showed high percentages of on-target base editing (e.g., NGC CBEs 454, 459 and 449, Table 13) were assessed with gRNAs of different lengths. In vitro cell-based assays were carried out to assess base editing efficiency and on-target versus bystander editing percentages of NGC CBEs encoded by mRNA. (FIGS. 12A-12C). In FIGS. 12A-12C, mRNA340 refers to an mRNA encoding CBE #449 (Table 13) comprising the SpCas9 variant 225 (or PV225) and the cytidine deaminase PPAPOBEC1 H122A; mRNA341 refers to an mRNA encoding CBE #454 (Table 13) comprising the SpCas9 variant 226 (or PV226), FIGS. 3A-3C, and the cytidine deaminase PPAPOBEC1 H122A, the sequence of which is provided hereinabove; and mRNA342 refers to an mRNA encoding CBE #459 (Table 13) comprising the SpCas9 variant 244 (or PV244) and the cytidine deaminase PPAPOBEC1 H122A. As shown in FIGS. 12A-12C, mRNA 342 exhibited the fewest C to A or C to G transitions, particularly when used with the 18mer and 20mer gRNAs.

[0739] The results of the experiments described in Examples 3-6 supra demonstrate that a Cas9 variant, namely, a SpCas9 variant containing a combination of mutations conferring the ability to bind an NGC PAM (i.e., a 5′-NGC-3′ PAM variant) is a viable option for base editing to achieve a low percentage of off-target effects (bystander editing) and a high percentage of on-target base editing. The results further demonstrate that using the NGC CBEs as described herein provide greater than 40% on target efficiency while limiting the bystander editing. These NGC CBEs are able to be encoded by mRNA, which showed efficient base editing when assayed in a cell-based system. In particular, gRNAs of certain lengths, for example, 18mer (e.g., G and 20mer gRNAs, can further decrease bystander (off-target) editing. Accordingly, the NGC CBEs described herein, and compositions and methods thereof, provide beneficial and useful therapeutics for treating SDS.

Example 7 Materials and Methods

[0740] The results provided in the Examples described herein were obtained using the following materials and methods.

Cloning.

[0741] DNA sequences of target polynucleotides and gRNAs and primers used are described herein. The following scaffold olynucleotide sequence was employed in the experiments described herein:

TABLE-US-00097 GTTTTAGAGCTAGAAATAGCAAGTTAAAATAAGGCTAGTCCGTTATCAA CTTGAAAAAGTGGCACCGAGTCGGTGCTTTTTTT. For gRNAs, the scaffold sequence is presented as follows, wherein uracil (U) replaces thymidine (T) in RNA: GUUUUAGAGC UAGAAAUAGC AAGUUAAAAU AAGGCUAGUC CGUUAUCAAC UUGAAAAAGU GGCACCGAGU CGGUGCUUUU(UUU).

[0742] The gRNA encompasses the scaffold sequence and the spacer sequence (target sequence) for an SDS gene comprising a pathogenic mutation as described herein or as determined based on the knowledge of the skilled practitioner and as would be understood to the skilled practitioner in the art.

[0743] Methods for base editing are known in the art. See, e.g., Komor, A. C., et al., “Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage” Nature 533, 420-424 (2016); Gaudelli, N. M., et al., “Programmable base editing of A⋅T to G⋅C in genomic DNA without DNA cleavage” Nature 551, 464-471 (2017); Komor, A. C., et al., “Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity” Science Advances 3:eaao4774 (2017), and Rees, H. A., et al., “Base editing: precision chemistry on the genome and transcriptome of living cells.” Nat Rev Genet. 2018 December; 19(12):770-788. doi: 10.1038/s41576-018-0059-1.

[0744] PCR was performed using VeraSeq ULtra DNA polymerase (Enzymatics), or Q5 Hot Start High-Fidelity DNA Polymerase (New England Biolabs). Base Editor (BE) plasmids were constructed using USER cloning (New England Biolabs). Deaminase genes were synthesized as gBlocks Gene Fragments (Integrated DNA Technologies). Cas9 genes useful in the invention are listed below and described herein. Cas9 genes were obtained from previously reported plasmids. Deaminase and fusion genes were cloned into pCMV (mammalian codon-optimized) or pET28b (E. coli codon-optimized) backbones. sgRNA expression plasmids are constructed using site-directed mutagenesis.

[0745] Briefly, primers useful in the invention are 5′ phosphorylated using T4 Polynucleotide Kinase (New England Biolabs) according to the manufacturer's instructions. Next, PCR was performed using Q5 Hot Start High-Fidelity Polymerase (New England Biolabs) with the phosphorylated primers and the plasmid encoding a gene of interest as a template according to the manufacturer's instructions. PCR products were incubated with DpnI (20 U, New England Biolabs) at 37° C. for 1 hour, purified on a QIAprep spin column (Qiagen), and ligated using QuickLigase (New England Biolabs) according to the manufacturer's instructions. DNA vector amplification was carried out using Mach1 competent cells (ThermoFisher Scientific).

In Vitro Deaminase Assay on ssDNA.

[0746] Sequences of all ssDNA substrates were obtained using standard methods. All Cy3-labelled substrates are obtained from Integrated DNA Technologies (IDT). Deaminases were expressed in vitro using the TNT T7 Quick Coupled Transcription/Translation Kit (Promega) according to the manufacturer's instructions using 1 μg of plasmid. Following protein expression, 5 μl of lysate was combined with 35 μl of ssDNA (1.8 μM) and USER enzyme (1 unit) in CutSmart buffer (New England Biolabs) (50 mM potassium acetate, 29 mM Tris-acetate, 10 mM magnesium acetate, 100 μg ml-1 BSA, pH 7.9) and incubated at 37° C. for 2 h. Cleaved U-containing substrates were resolved from full-length unmodified substrates on a 10% TBE-urea gel (Bio-Rad).

Expression and Purification of Base Editors.

[0747] E. coli BL21 STAR (DE3)-competent cells (ThermoFisher Scientific) were transformed with plasmids (e.g. plasmids encoding pET28b-His6-PV1-14 or pET28b-His6-APOBEC-linker-dCas9). The resulting expression strains were grown overnight in Luria-Bertani (LB) broth containing 100 μg ml-1 of kanamycin at 37° C. The cells were diluted 1:100 into the same growth medium and grown at 37° C. to OD600=˜0.6. The culture was cooled to 4° C. over a period of 2 h, and isopropyl-β-d-1-thiogalactopyranoside (IPTG) was added at 0.5 mM to induce protein expression. After ˜16 h, the cells were collected by centrifugation at 4,000 g and were resuspended in lysis buffer (50 mM tris(hydroxymethyl)-aminomethane (Tris)-HCl (pH 7.5), 1 M NaCl, 20% glycerol, 10 mM tris(2-carboxyethyl)phosphine (TCEP, Soltec Ventures)). The cells were lysed by sonication (20 s pulse-on, 20 s pulse-off for 8 min total at 6 W output) and the lysate supernatant was isolated following centrifugation at 25,000 g for 15 minutes. The lysate was incubated with His-Pur nickel-nitriloacetic acid (nickel-NTA) resin (ThermoFisher Scientific) at 4° C. for 1 hour to capture the His-tagged fusion protein. The resin was transferred to a column and washed with 40 ml of lysis buffer. The His-tagged fusion protein was eluted in lysis buffer supplemented with 285 mM imidazole, and concentrated by ultrafiltration (Amicon-Millipore, 100-kDa molecular weight cut-off) to 1 ml total volume. The protein was diluted to 20 ml in low-salt purification buffer containing 50 mM tris(hydroxymethyl)-aminomethane (Tris)-HCl (pH 7.0), 0.1 M NaCl, 20% glycerol, 10 mM TCEP and was loaded onto SP Sepharose Fast Flow resin (GE Life Sciences). The resin was washed with 40 ml of this low-salt buffer, and the protein was eluted with 5 ml of activity buffer containing 50 mM tris(hydroxymethyl)-aminomethane (Tris)-HCl (pH 7.0), 0.5 M NaCl, 20% glycerol, 10 mM TCEP. The eluted proteins were quantified by SDS-PAGE.

In Vitro Transcription of sgRNAs.

[0748] Linear DNA fragments containing the T7 promoter followed by the 20-bp sgRNA target sequence were transcribed in vitro using the TranscriptAid T7 High Yield Transcription Kit (ThermoFisher Scientific) according to the manufacturer's instructions. sgRNA products were purified using the MEGAclear Kit (ThermoFisher Scientific) according to the manufacturer's instructions and quantified by UV absorbance.

Preparation of Cy3-Conjugated dsDNA Substrates.

[0749] Typically, unlabled sequence strands (e.g. sequences of 80-nt unlabelled strands) are ordered as PAGE-purified oligonucleotides from IDT. A 25-nt Cy3-labelled primer complementary to the 3′ end of each 80-nt substrate is ordered as an HPLC-purified oligonucleotide from IDT. To generate the Cy3-labelled dsDNA substrates, the 80-nt strands (5 μl of a 100 μM solution) were combined with the Cy3-labelled primer (5 μl of a 100 μM solution) in NEBuffer 2 (38.25 μl of a 50 mM NaCl, 10 mM Tris-HCl, 10 mM MgCl.sub.2, 1 mM DTT, pH 7.9 solution, New England Biolabs) with dNTPs (0.75 μl of a 100 mM solution) and heated to 95° C. for 5 min, followed by a gradual cooling to 45° C. at a rate of 0.1° C. per s. After this annealing period, Klenow exo— (5 U, New England Biolabs) was added and the reaction is incubated at 37° C. for 1 hour (h). The solution was diluted with buffer PB (250 μl, Qiagen) and isopropanol (50 μl) and purified on a QIAprep spin column (Qiagen), eluting with 50 μl of Tris buffer.

[0750] Deaminase Assay on dsDNA.

[0751] The purified fusion protein (20 μl of 1.9 μM in activity buffer) was combined with 1 equivalent of appropriate sgRNA and incubated at ambient temperature for 5 minutes. The Cy3-labelled dsDNA substrate was added to final concentration of 125 nM and the resulting solution was incubated at 37° C. for 2 h. The dsDNA is separated from the fusion by the addition of buffer PB (100 μl, Qiagen) and isopropanol (25 μl) and purified on a EconoSpin micro spin column (Epoch Life Science), eluting with 20 μl of CutSmart buffer (New England Biolabs). USER enzyme (1 U, New England Biolabs) is added to the purified, edited dsDNA and incubated at 37° C. for 1 h. The Cy3-labeled strand was fully denatured from its complement by combining 5 μl of the reaction solution with 15 μl of a DMSO-based loading buffer (5 mM Tris, 0.5 mM EDTA, 12.5% glycerol, 0.02% bromophenol blue, 0.02% xylene cyan, 80% DMSO). The full-length C-containing substrate was separated from any cleaved, U-containing edited substrates on a 10% TBE-urea gel (Bio-Rad) and imaged on a GE Amersham Typhoon imager.

Preparation of In Vitro-Edited dsDNA for High-Throughput Sequencing.

[0752] Oligonucleotides were obtained from IDT. Complementary sequences were combined (5 μl of a 100 μM solution) in Tris buffer and annealed by heating to 95° C. for 5 min, followed by a gradual cooling to 45° C. at a rate of 0.1° C. per s to generate 60-bp dsDNA substrates. Purified fusion protein (20 μl of 1.9 μM in activity buffer) was combined with 1 equivalent of appropriate sgRNA and incubated at ambient temperature for 5 min. The 60-mer dsDNA substrate was added to final concentration of 125 nM, and the resulting solution is incubated at 37° C. for 2 h. The dsDNA was separated from the fusion by the addition of buffer PB (100 μl, Qiagen) and isopropanol (25 μl) and purified on a EconoSpin micro spin column (Epoch Life Science), eluting with 20 μl of Tris buffer. The resulting edited DNA (1 μl is used as a template) was amplified by PCR using high-throughput sequencing primer pairs and VeraSeq Ultra (Enzymatics) according to the manufacturer's instructions with 13 cycles of amplification. PCR reaction products were purified using RapidTips (Diffinity Genomics), and the purified DNA is amplified by PCR with primers containing sequencing adapters, purified, and sequenced on a MiSeq high-throughput DNA sequencer (Illumina) as previously described.

Cell Culture.

[0753] HEK293T (ATCC CRL-3216) and U2OS (ATCC HTB-96) expressing wild-type SDSP or mutant SDSP were maintained in Dulbecco's Modified Eagle's Medium plus GlutaMax (ThermoFisher) supplemented with 10% (v/v) fetal bovine serum (FBS), at 37° C. with 5% CO2. HCC1954 cells (ATCC CRL-2338) were maintained in RPMI-1640 medium (ThermoFisher Scientific) supplemented as described above. Immortalized cells containing SDSP) (Taconic Biosciences) were cultured in Dulbecco's Modified Eagle's Medium plus GlutaMax (ThermoFisher Scientific) supplemented with 10% (v/v) fetal bovine serum (FBS) and 200 μg ml-1 Geneticin (ThermoFisher Scientific).

Transfections.

[0754] HEK 293T cells (ATCC CRL-3216) maintained in Dulbecco's Modified Eagle's Medium plus GlutaMax (Thermo Fisher Scientific) supplemented with 10% (v/v) FBS at 37° C. with 5% CO.sub.2 were seeded on 48-well collagen-coated BioCoat plates (Corning) and transfected at approximately 80-85% confluency. Briefly, 750 ng of BE or other cytidine deaminase and/or 200 ng of SpCas9, and 250 ng of sgRNA expression plasmids were transfected using 1.5 μl of Lipofectamine 2000 (ThermoFisher Scientific) per well according to the manufacturer's protocol. HEK293T cells were transfected using appropriate Amaxa Nucleofector II programs according to manufacturer's instructions (V kits using program Q-001 for HEK293T cells). In some cases, cells were cultured for 3 days post-transfection before the medium was removed. Cells were washed with 1×PBS solution (Thermo Fisher Scientific), and genomic DNA was extracted by addition of 30 μL lysis buffer (10 mM Tris-HCl, pH 7.0, 0.05% SDS, 25 Proteinase K (Thermo Fischer Scientific). Genomic DNA was stored at −20° C. until further use.

High-Throughput DNA Sequencing of Genomic DNA Samples.

[0755] Transfected cells were harvested after 3 days, and the genomic DNA was isolated using the Agencourt DNAdvance Genomic DNA Isolation Kit (Beckman Coulter) according to the manufacturer's instructions. On-target and off-target genomic regions of interest were amplified by PCR with flanking high-throughput sequencing primer pair. PCR amplification was carried out with Phusion high-fidelity DNA polymerase (ThermoFisher) according to the manufacturer's instructions using 5 ng of genomic DNA as a template. Cycle numbers were determined separately for each primer pair as to ensure the reaction was stopped in the linear range of amplification. PCR products were purified using RapidTips (Diffinity Genomics). Purified DNA was amplified by PCR with primers containing sequencing adaptors. The products were gel purified and quantified using the Quant-iT PicoGreen dsDNA Assay Kit (ThermoFisher) and KAPA Library Quantification Kit-Illumina (KAPA Biosystems). Samples were sequenced on an Illumina MiSeq as previously described (Pattanayak, Nature Biotechnol. 31, 839-843 (2013)).

Data Analysis.

[0756] Sequencing reads were automatically demultiplexed using MiSeq Reporter (Illumina), and individual FASTQ files were analysed with a custom Matlab. Each read was pairwise aligned to the appropriate reference sequence using the Smith-Waterman algorithm. Base calls with a Q-score below 31 were replaced with Ns and were thus excluded in calculating nucleotide frequencies. This treatment yields an expected MiSeq base-calling error rate of approximately 1 in 1,000. Aligned sequences in which the read and reference sequence contained no gaps were stored in an alignment table from which base frequencies could be tabulated for each locus. Indel frequencies were quantified with a custom Matlab script using previously described criteria (Zuris, et al., Nature Biotechnol. 33, 73-80 (2015). Sequencing reads were scanned for exact matches to two 10-bp sequences that flank both sides of a window in which indels might occur. If no exact matches were located, the read was excluded from analysis. If the length of this indel window exactly matched the reference sequence the read was classified as not containing an indel. If the indel window was two or more bases longer or shorter than the reference sequence, then the sequencing read was classified as an insertion or deletion, respectively.

OTHER EMBODIMENTS

[0757] From the foregoing description, it will be apparent that variations and modifications may be made to the invention described herein to adopt it to various usages and conditions. Such embodiments are also within the scope of the following claims.

[0758] The recitation of a listing of elements in any definition of a variable herein includes definitions of that variable as any single element or combination (or subcombination) of listed elements. The recitation of an embodiment herein includes that embodiment as any single embodiment or in combination with any other embodiments or portions thereof.

INCORPORATION BY REFERENCE

[0759] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. Absent any indication otherwise, publications, patents, and patent applications mentioned in this specification are incorporated herein by reference in their entireties.