Disclosed herein are methods and compositions comprising a polymerase and a phosphorylated nucleoside, wherein the polymerase and the nucleoside are covalently linked by a cleavable linker at the terminal phosphate group. Further disclosed herein are enzymatic polynucleotide synthesis using polymerase and nucleotide conjugation strategies.

Provided are methods of adding adapters to nucleic acids. The methods include combining in a reaction mixture a template ribonucleic acid (RNA), a template switch oligonucleotide including a 3′ hybridization domain and a sequencing platform adapter construct, a polymerase, and dNTPs. The reaction mixture components are combined under conditions sufficient to produce a product nucleic acid that includes the template RNA and the template switch oligonucleotide each hybridized to adjacent regions of a single product nucleic acid that includes a region polymerized from the dNTPs by the polymerase. Aspects of the invention further include compositions and kits.

The present disclosure provides methods, compositions, kits and systems for nucleic acid amplification. In some embodiments, nucleic acid amplification methods include subjecting the nucleic acid to be amplified to partially denaturing conditions. In some embodiments, nucleic acid amplification methods include amplifying without fully denaturing the nucleic acid that is amplified. In some embodiments, the nucleic acid amplification method employs an enzyme that catalyzes homologous recombination and a polymerase. In some embodiments, methods for nucleic acid amplification can be conducted in a single reaction vessel and/or in a single continuous liquid phase of a reaction mixture, without need for compartmentalization of the reaction mixture or immobilization of reaction components. In some embodiments, methods for nucleic acid amplification comprise amplifying at least one polynucleotide onto a surface under isothermal amplification conditions, optionally in the presence of a polymer which can include a sieving agent and/or a diffusion-reducing agent.

Multiple polynucleotides having different, arbitrary sequences are synthesized on the surface of an array by spatial control of polymerase activity. The polymerase is a template-independent polymerase such as terminal deoxynucleotidyl transferase (TdT). Spatial control of polymerase activity is implemented by localized changes in redox-pH conditions. A single species of nucleotide is added and incorporated on growing polynucleotide strands at locations on the array where the polymerase is active. A washing step removes the polymerase and free nucleotides. This process may be repeated multiple times changing both the location of polymerase activity and the species of nucleotide thereby synthesizing different polynucleotides in parallel on the surface of the array. Polymerase activity may be regulated by removing a blocking group attached to a His-tag sequence on the polymerase, a change in pH, or release of encapsulated inhibitors.

The present disclosure provides compositions, methods, kits, systems and apparatus that are useful for nucleic acid polymerization. In particular, modified polymerases and biologically active fragments thereof, such as modified Taq polymerases, are provided that allow for improved nucleic acid amplification. In some aspects, the disclosure provides modified polymerases having improved thermostability, accuracy, processivity and/or read length as compared to a referenceTaq polymerase. In some aspects, the disclosure relates to modified polymerases or biologically active fragments thereof, useful for amplification methods, and in practically illustrative embodiments, emulsion PCR.

Described herein are polymerase variants that are exonuclease deficient. Some variants retain the strand displacement capability comparable to the wild-type or parental polymerase. Some variants have a strand displacement capability that is improved relative to the wild-type or parental polymerase. The variants may have an extension rate that is greater than the wild-type or parental polymerase. The variants may have a waiting time that is less than the wild-type or parental polymerase.

Compositions comprising modified recombinant polymerizing enzymes are provided, along with nucleic acid molecules encoding the modified polymerizing enzymes. In some aspects, methods of using such polymerizing enzymes to synthesize a nucleic acid molecule or to sequence a nucleic acid template are provided.

Provided are methods and compositions for activating oligonucleotide aptamer-deactivated DNA polymerases, comprising cleaving the aptamer by endonuclease V enzymatic activity to reduce or eliminate binding of the oligonucleotide aptamer to the DNA polymerase, thereby activating DNA synthesis activity of the DNA polymerase in a reaction mixture. Mixtures for use in methods of the invention are also provided. In some aspects, the oligonucleotide aptamer comprises one or more deoxyinosine nucleotides providing for aptamer-specific recognition and cleavage of the aptamer by the endonuclease V enzymatic activity. Exemplary oligonucleotide aptamers, mixtures and methods employing endonuclease V enzymatic activity are provided. The methods can be practiced using kits comprising a DNA polymerase-binding oligonucleotide aptamer and at least one endonuclease V enzymatic activity having oligonucleotide aptamer-specific recognition to provide for specific cleavage of the aptamer by the endonuclease V enzymatic activity.

Provided herein are modified Archaeal family B polymerases derived from species of the Archaeal microorganism Pyrococcus that exhibit improved incorporation of nucleotide analogues utilized in DNA sequencing.

The present disclosure provides variant OmpG polypeptides, compositions comprising the OmpG variant polypeptides, and methods for using the variant OmpG polypeptides as nanopores for determining the sequence of single stranded nucleic acids. The variant OmpG nanopores reduce the ionic current noise versus the parental OmpG polypeptide from which they are derived and thereby enable sequencing of polynucleotides with single nucleotide resolution. The reduced ionic current noise also provides for the use of these OmpG nanopore variants in other single molecule sensing applications, e.g., protein sequencing.