title: Replication, repair, and translesion polymerase bypass of N⁶-oxopropenyl-2'-deoxyadenosine.
abstract: The oxidative stress products malondialdehyde and base propenal react with DNA bases forming the adduction products 3-(2'-deoxy-β-D-erythro-pentofuranosyl)pyrimido[1,2-a]purin-10(3H)-one (M1dG) and N(6)-(oxypropenyl)-2'-deoxyadenosine (OPdA). M1dG is mutagenic in vivo and miscodes in vitro, but little work has been done on OPdA. To improve our understanding of the effect of OPdA on polymerase activity and mutagenicity, we evaluated the ability of the translesion DNA polymerases hPols η, κ, and ι to bypass OPdA in vitro. hPols η and κ inserted dNTPs opposite the lesion and extended the OPdA-modified primer to the terminus. hPol ι inserted dNTPs opposite OPdA but failed to fully extend the primer. Steady-state kinetic analysis indicated that these polymerases preferentially insert dTTP opposite OPdA, although less efficiently than opposite dA. Minimal incorrect base insertion was observed for all polymerases, and dCTP was the primary mis-insertion event. Examining replicative and repair polymerases revealed little effect of OPdA on the Sulfolobus solfataricus polymerase Dpo1 or the Klenow fragment of Escherichia coli DNA polymerase I. Bacteriophage T7 DNA polymerase displayed a reduced level of OPdA bypass compared to unmodified DNA, and OPdA nearly completely blocked the activity of base excision repair polymerase hPol β. This work demonstrates that bypass of OPdA is generally error-free, modestly decreases the catalytic activity of most polymerases, and blocks hPol β polymerase activity. Although mis-insertion opposite OPdA is relatively weak, the efficiency of bypass may introduce A → G transitions observed in vivo.
authors.affiliation: A. B. Hancock Jr. Memorial Laboratory for Cancer Research, †Department of Biochemistry, ‡Department of Chemistry, and §Department of Pharmacology, Center in Molecular Toxicology, Vanderbilt Institute of Chemical Biology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States.
authors.forename: Leena
authors.initials: L
authors.lastname: Maddukuri
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Shuck
authors.forename: Robert L
authors.initials: RL
authors.lastname: Eoff
authors.forename: Linlin
authors.initials: L
authors.lastname: Zhao
authors.forename: Carmelo J
authors.initials: CJ
authors.lastname: Rizzo
authors.forename: F Peter
authors.initials: FP
authors.lastname: Guengerich
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Marnett
mesh_terms: D004256:DNA Polymerase I / Q000378:metabolism; D004260:DNA Repair / Q000502:physiology*; D004261:DNA Replication / Q000502:physiology*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D003839:Deoxyadenosines / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009152:Mutagenicity Tests; D009153:Mutagens; D048229:Sulfolobus solfataricus / Q000201:enzymology
chemical_list: D003839:Deoxyadenosines; D009153:Mutagens; C586683:N6-oxopropenyl-2'-deoxyadenosine; D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase; C058118:2'-deoxyadenosine