Nucleic Acids Research Advance Access originally published online on May 22, 2008
Nucleic Acids Research 2008 36(12):3867-3878; doi:10.1093/nar/gkn309
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Nucleic Acids Research, 2008, Vol. 36, No. 12 3867-3878
© 2008 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nucleic Acid Enzymes |
Mechanism of double-base lesion bypass catalyzed by a Y-family DNA polymerase
1Department of Biochemistry, 2Ohio State Biochemistry Program, 3Ohio State Biophysics Program, 4Molecular, Cellular & Developmental Biology Program and 5Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
*To whom correspondence should be addressed. Tel: +1 614 688 3706; Fax: +1 614 292 6773; Email: suo.3{at}osu.edu
Received March 2, 2008. Revised April 29, 2008. Accepted April 30, 2008.
As a widely used anticancer drug, cis-diamminedichloroplatinum(II) (cisplatin) reacts with adjacent purine bases in DNA to form predominantly cis-[Pt(NH3)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.