Incorporation of nucleoside probes opposite O⁶-methylguanine by Sulfolobus solfataricus DNA polymerase Dpo4: importance of hydrogen bonding.

Stornetta A, Angelov T, Guengerich FP, Sturla SJ
Chembiochem. 2013 14 (13): 1634-9

PMID: 23959784 · PMCID: PMC3896954 · DOI:10.1002/cbic.201300296

O⁶-Methylguanine (O⁶-MeG) is a mutagenic DNA lesion, arising from the action of methylating agents on guanine (G) in DNA. Dpo4, an archaeal low-fidelity Y-family DNA polymerase involved in translesion DNA synthesis (TLS), is a model for studying how human Y-family polymerases bypass DNA adducts. Previous work showed that Dpo4-mediated dTTP incorporation is favored opposite O⁶-MeG rather than opposite G. However, factors influencing the preference of Dpo4 to incorporate dTTP opposite O⁶-MeG are not fully defined. In this study, we investigated the influence of structural features of incoming dNTPs on their enzymatic incorporation opposite O⁶-MeG in a DNA template. To this end, we utilized a new fluorescence-based primer extension assay to evaluate the incorporation efficiency of a panel of synthetic dNTPs opposite G or O⁶-MeG by Dpo4. In single-dNTP primer extension studies, the synthetic dNTPs were preferentially incorporated opposite G, relative to O⁶-MeG. Moreover, pyrimidine-based dNTPs were generally better incorporated than purine-based syn-conformation dNTPs. The results suggest that hydrophobicity of the incoming dNTP appears to have little influence on the process of nucleotide selection by Dpo4, with hydrogen bonding capacity being a major influence. Additionally, modifications at the C2-position of dCTP increase the selectivity for incorporation opposite O⁶-MeG without a significant loss of efficiency.

Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

MeSH Terms (7)

DNA Polymerase beta Fluorescent Dyes Guanine Hydrogen Bonding Molecular Structure Nucleosides Sulfolobus solfataricus

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