Abstract: Provided are compositions comprising recombinant DNA polymerases that include amino acid substitutions, insertions, deletions and/or heterologous or exogenous features that confer modified properties upon the polymerase for enhanced single molecule sequencing. Such properties can include reduced reaction rates at one or more steps of the polymerase kinetic cycle, increased closed polymerase/DNA complex stability, enhanced metal ion coordination, reduced exonuclease activity, decreased branching fractions, and the like. Polymerases that exhibit branching fractions that are less than the branching fractions of the polymerases from which they were derived, or branching fractions that are less than about 25% for a phosphate-labeled nucleotide analog, are also provided. Also provided are nucleic acids which encode the polymerases with the aforementioned phenotypes, as well as methods of using such polymerases to make a DNA or to sequence a DNA template.

Abstract: Systems and methods are provided for single-molecule sequencing of template nucleic acids in which the signal from a label attached to a polymerase enzyme is used to monitor conformational changes in the polymerase which occur while labeled nucleotides or nucleotide analogs are added to a growing nucleic acid chain which is complementary to the template nucleic acid. The signal indicative of the conformational state of the enzyme is used to determine with higher confidence when true nucleotide or nucleotide analog incorporation events occur, allowing for the improved quality of base calls and sequence determination.

Abstract: Compositions that include polymerases with features for improving entry of nucleotide analogues into active site regions and for coordinating with the nucleotide analogues in the active site region are provided. Methods of making the polymerases and of using the polymerases in sequencing and DNA replication and amplification as well as kinetic models of polymerase activity and computer-implemented methods of using the models are also provided.

Abstract: Provided are compositions comprising modified recombinant polymerases that exhibit branching fractions that are less than the branching fractions of the polymerases from which they were derived, or branching fractions that are less than about 25% for a phosphate-labeled nucleotide analog. Also provided are compositions comprising modified recombinant polymerases that exhibit closed polymerase/DNA complexes with increased stability relative to the parental polymerases. Also provided are compositions comprising modified recombinant polymerases that exhibit decreased rate constants relative to the parental polymerases. Provided are methods for generating polymerases with the aforementioned phenotypes. Provided are methods of using such polymerases to make a DNA or to sequence a DNA template.

Abstract: Provided are compositions comprising modified DNA polymerases that exhibit improved photostability compared to the parental polymerases from which they were derived. Provided are methods for generating enzymes, such as DNA polymerases, with the aforementioned phenotype. Provided are methods of using polymerases with increased resistance to photodamage to make a DNA or to sequence a DNA template.

Abstract: Methods of screening for and selecting for improved polymerases suitable for single molecule sequencing are provided.