title: Mechanism of double-base lesion bypass catalyzed by a Y-family DNA polymerase.
abstract: As a widely used anticancer drug, cis-diamminedichloroplatinum(II) (cisplatin) reacts with adjacent purine bases in DNA to form predominantly cis-[Pt(NH(3))(2){d(GpG)-N7(1),-N7(2)}] intrastrand cross-links. Drug resistance, one of the major limitations of cisplatin therapy, is partially due to the inherent ability of human Y-family DNA polymerases to perform translesion synthesis in the presence of DNA-distorting damage such as cisplatin-DNA adducts. To better understand the mechanistic basis of translesion synthesis contributing to cisplatin resistance, this study investigated the bypass of a single, site-specifically placed cisplatin-d(GpG) adduct by a model Y-family DNA polymerase, Sulfolobus solfataricus DNA polymerase IV (Dpo4). Dpo4 was able to bypass this double-base lesion, although, the incorporation efficiency of dCTP opposite the first and second cross-linked guanine bases was decreased by 72- and 860-fold, respectively. Moreover, the fidelity at the lesion decreased up to two orders of magnitude. The cisplatin-d(GpG) adduct affected six downstream nucleotide incorporations, but interestingly the fidelity was essentially unaltered. Biphasic kinetic analysis supported a universal kinetic mechanism for the bypass of DNA lesions catalyzed by various translesion DNA polymerases. In conclusion, if human Y-family DNA polymerases adhere to this bypass mechanism, then translesion synthesis by these error-prone enzymes is likely accountable for cisplatin resistance observed in cancer patients.
authors.affiliation: Department of Biochemistry, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Brown
authors.forename: Sean A
authors.initials: SA
authors.lastname: Newmister
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Fiala
authors.forename: Zucai
authors.initials: Z
authors.lastname: Suo
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D002384:Catalysis; D002945:Cisplatin / Q000378:metabolism* / Q000627:therapeutic use; D004247:DNA / Q000096:biosynthesis / Q000737:chemistry; D004249:DNA Damage; D019951:DNA Polymerase beta / Q000378:metabolism*; D015226:Dinucleoside Phosphates / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm; D007700:Kinetics; D009711:Nucleotides / Q000378:metabolism; D048229:Sulfolobus solfataricus / Q000201:enzymology
chemical_list: D000970:Antineoplastic Agents; D015226:Dinucleoside Phosphates; D009711:Nucleotides; C094059:cisplatin-deoxy(guanosine monophosphate guanosine) adduct; D004247:DNA; D019951:DNA Polymerase beta; D002945:Cisplatin