The present invention features fusion polypeptides comprising an RNA binding polypeptide operationally linked to an RNA modifying enzyme (e.g., adenosine deaminase, cytidine deaminase), and methods of use therefore.

Provided are fusion proteins and related molecules useful for conducting base editing with reduced or no off-target mutations. The fusion protein may include a first fragment comprising a nucleobase deaminase or a catalytic domain thereof, a second fragment comprising a nucleobase deaminase inhibitor, and a protease cleavage site between the first fragment and the second fragment. Also provided are improved prime editing systems, including prime editing guide RNA with improved stability.

The present invention relates to a chimeric enzyme comprising a CRISPR class 2 type II enzyme backbone, wherein the HNH domain in the backbone has been replaced, essentially, by a peptide or protein domain having catalytic activity on a single stranded polynucleotide.

The instant specification provides novel assays and systems for determining off-target effects of base editors. These assays and systems may comprise bacterial and/or eukaryotic cell systems and may be used to determine off-target editing frequencies, including Cas9-independent off-target editing frequencies. Also provided herein are novel base editors, wherein the base editors have reduced Cas9-independent off-target editing frequencies while maintaining high on-target editing efficiencies. Further provided are methods of contacting a nucleic acid molecule with these base editors to obtain reduced off-target editing frequencies, and in particular reduced Cas9-independent off-target editing events. Further provided are methods of treatment comprising administering these base editors to a subject. Also provided are pharmaceutical compositions comprising the base editors described herein, and nucleic acids, vectors, cells, and kits useful for the generation of these base editors.

The disclosure provides adenosine deaminases that are capable of deaminating adenosine in DNA to treat cancers, such as melanoma and glioblastoma. The disclosure also provides fusion proteins, guide RNAs and compositions comprising a Cas9 (e.g., a Cas9 nickase) domain and adenosine deaminases that deaminate adenosine in DNA, for example in a STAT3 gene. In some embodiments, adenosine deaminases provided herein are used to modify the STAT3 gene so that its protein product, STAT3, is unable to be activated. In some embodiments, the methods and compositions provided herein are used to treat melanoma or glioblastoma.

The disclosure provides methods of deaminating adenosine and cytosine bases in a target nucleic acid sequence in an USH2A gene comprising contacting the USH2A gene with a base editor in association with a guide RNA (gRNA). In some aspects, base editing is used to restore US2HA function by disrupting a splice site in the USH2A gene sequence to induce skipping of an exon containing a mutation, while in other embodiments, base editing is used to restore US2HA function by correcting a point mutation e.g., in an exon) so as to correct mutations. The disclosure also provides complexes of adenosine base editors and guide RNAs, and complexes of cytidine base editors and guide RNAs. The disclosure further provides pharmaceutical compositions and cells comprising these complexes. The disclosure also provides vectors encoding these complexes, base editors, and gRNAs. In some embodiments, the methods and compositions provided herein are used to treat Usher syndrome and autosomal recessive retinitis pigmentosa (arRP).

The present disclosure relates to nucleobase editors and methods of use thereof. Disclosed herein are fusion proteins, systems, and compositions for editing disease-associated mutations and methods of use thereof. In some aspects, disclosed herein is a fusion protein comprising a Cas9 nickase and a nucleotide deaminase, wherein the Cas9 nickase comprises a first amino acid substitution at a position selected from the group consisting of 262, 324, 409, 480, 543, 694, and 1219 when compared to SEQ ID NO: 11, and wherein the Cas9 nickase comprises a second amino acid substitution at a position selected from the group consisting of 1111, 1135, 1218, 1219, 1322, 1335, and 1337 when compared to SEQ ID NO: 11.

The present invention concerns a method to modulate the level of or to modify a target molecule in a subject or an environment, said method comprising: administering in said subject or providing to said environment an engineered bacterial strain comprising (i) a heterologous or engineered nucleic acid involved in the expression of a molecule of interest, wherein the expression of said molecule of interest modulates directly or indirectly the level of or modify the target molecule in said subject or environment and (ii) an autologous gene or gene set involved in the import and/or metabolism of a milk oligosaccharide; and further administering to said subject, or providing to said environment, said milk oligosaccharide; whereby the level of the target molecule in said subject or environment is modulated or the target molecule is modified in said subject or environment.

The invention features compositions and methods for introducing mutations into the hepatitis B virus (HBV) genome.

The present disclosure provides improved adenosine base editors (ABE) that have an expanded range of PAM sequence recognition capability (i.e., recognition of non-canonical ′5-NGG-′3 PAM sequence). In addition, the present disclosure provides improved cytidine base editors (CBE) and adenosine base editors (ABE) comprising circular permutant variants of Cas9 (CP-Cas9) with an increased window of base editing within the protospacer sequence (e.g., from about 4-5 nucleotides to up to about 8-9 nucleotides) and even outside of the protospacer sequence.