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Mol Cell Biol. 2005 Mar;25(6):2169-76.

Mechanism of efficient and accurate nucleotide incorporation opposite 7,8-dihydro-8-oxoguanine by Saccharomyces cerevisiae DNA polymerase eta.

Author information

1
Department of Biochemistry, 4-403 Bowen Science Building, University of Iowa, Iowa City, IA 52242-1109, USA.

Abstract

Most DNA polymerases incorporate nucleotides opposite template 7,8-dihydro-8-oxoguanine (8-oxoG) lesions with reduced efficiency and accuracy. DNA polymerase (Pol) eta, which catalyzes the error-free replication of template thymine-thymine (TT) dimers, has the unique ability to accurately and efficiently incorporate nucleotides opposite 8-oxoG templates. Here we have used pre-steady-state kinetics to examine the mechanisms of correct and incorrect nucleotide incorporation opposite G and 8-oxoG by Saccharomyces cerevisiae Pol eta. We found that Pol eta binds the incoming correct dCTP opposite both G and 8-oxoG with similar affinities, and it incorporates the correct nucleotide bound opposite both G and 8-oxoG with similar rates. While Pol eta incorporates an incorrect A opposite 8-oxoG with lower efficiency than it incorporates a correct C, it does incorporate A more efficiently opposite 8-oxoG than opposite G. This is mainly due to greater binding affinity for the incorrect incoming dATP opposite 8-oxoG. Overall, these results show that Pol eta replicates through 8-oxoG without any barriers introduced by the presence of the lesion.

PMID:
15743815
PMCID:
PMC1061627
DOI:
10.1128/MCB.25.6.2169-2176.2005
[Indexed for MEDLINE]
Free PMC Article

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