Efficient and High Fidelity Incorporation of Dye-terminators by a Novel Archaeal DNA Polymerase Mutant

We examined the molecular basis of ddNTP selectivity in archaeal family B DNA polymerases by randomly mutagenizing the gene encoding Thermococcus sp. JDF-3 DNA polymerase and screening mutant libraries for improved ddNTP incorporation. We identified two mutations, P410L and A485T, that improved ddNT...

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Bibliographic Details
Published in:Journal of molecular biology 2002-09, Vol.322 (4), p.719-729
Main Authors: Arezi, Bahram, Hansen, Connie J, Hogrefe, Holly H
Format: Article
Language:English
Subjects:
archaeal DNA polymerase
Base Sequence
Coloring Agents
dideoxynucleoside triphosphate
Dideoxynucleosides - metabolism
DNA, Archaeal
DNA-Directed DNA Polymerase - genetics
DNA-Directed DNA Polymerase - metabolism
JDF-3 DNA polymerase
Kinetics
minisequencing
Molecular Sequence Data
Mutagenesis
Rhodamines - metabolism
single nucleotide polymorphism
Thermococcus - enzymology
Thermococcus - genetics
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Summary:We examined the molecular basis of ddNTP selectivity in archaeal family B DNA polymerases by randomly mutagenizing the gene encoding Thermococcus sp. JDF-3 DNA polymerase and screening mutant libraries for improved ddNTP incorporation. We identified two mutations, P410L and A485T, that improved ddNTP uptake, suggesting the contribution of P410 and A485 to ddNTP/dNTP selectivity in archaeal DNA polymerases. The importance of A485 was identified previously in mutagenesis studies employing Pfu (A486) and Vent (A488) DNA polymerases, while the contribution of P410 to ddNTP/dNTP selectivity has not been reported. We demonstrate that a combination of mutations (P410L/A485T) has an additive effect in improving ddNTP incorporation by a total of 250-fold. To assess the usefulness of the JDF-3 P410L/A485T in fluorescent-sequencing applications, we compared the archaeal mutant to Taq F667Y with respect to fidelity and kinetic parameters for DNA and dye-ddNTPs. Although the Taq F667Y and JDF-3 P410L/A485T mutants exhibit similar K m and V max values for dye-ddNTPs in single-base extension assays, the archaeal mutant exhibits higher fidelity due to a reduced tendency to form certain (ddG:dT, ddT:dC) mispairs. DNA polymerases exhibiting higher insertion fidelity are expected to provide greater accuracy in SNP frequency determinations by single-base extension and in multiplex minisequencing assays.
ISSN:0022-2836
1089-8638
DOI:10.1016/S0022-2836(02)00843-4