title: The efficiency and fidelity of translesion synthesis past cisplatin and oxaliplatin GpG adducts by human DNA polymerase beta.
abstract: DNA polymerase beta (pol beta) is the only mammalian DNA polymerase identified to date that can catalyze extensive bypass of platinum-DNA adducts in vitro. Previous studies suggest that DNA synthesis by pol beta is distributive on primed single-stranded DNA and processive on gapped DNA. The data presented in this paper provide an analysis of translesion synthesis past cisplatin- and oxaliplatin-DNA adducts by pol beta functioning in both distributive and processive modes using primer extension and steady-state kinetic experiments. Translesion synthesis past Pt-DNA adducts was greater with gapped DNA templates than with single-stranded DNA templates. In the processive mode pol beta did not discriminate between cisplatin and oxaliplatin adducts, while in the distributive mode it displayed about 2-fold increased ability for translesion synthesis past oxaliplatin compared with cisplatin adducts. The differentiation between cisplatin and oxaliplatin adducts resulted from a K(m)-mediated increase in the efficiency of dCTP incorporation across from the 3'-G of oxaliplatin-GG adducts. Rates of misincorporation across platinated guanines determined by the steady-state kinetic assay were higher in reactions with primed single-stranded templates than with gapped DNA and a slight increase in the misincorporation of dTTP across from the 3'-G was found for oxaliplatin compared with cisplatin adducts.
authors.affiliation: Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina, Chapel Hill 27599-7260, USA.
authors.forename: A
authors.initials: A
authors.lastname: Vaisman
authors.forename: S G
authors.initials: SG
authors.lastname: Chaney
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001483:Base Sequence; D002945:Cisplatin / Q000494:pharmacology*; D018736:DNA Adducts / Q000378:metabolism*; D019951:DNA Polymerase beta / Q000378:metabolism*; D017931:DNA Primers / Q000378:metabolism; D004260:DNA Repair; D004261:DNA Replication; D003845:Deoxycytosine Nucleotides / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D000077150:Oxaliplatin; D011994:Recombinant Proteins / Q000378:metabolism; D013942:Thymine Nucleotides / Q000378:metabolism; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D018736:DNA Adducts; D017931:DNA Primers; D003845:Deoxycytosine Nucleotides; D009944:Organoplatinum Compounds; D011994:Recombinant Proteins; D013942:Thymine Nucleotides; D000077150:Oxaliplatin; C024107:2'-deoxycytidine 5'-triphosphate; D019951:DNA Polymerase beta; D002945:Cisplatin; C024157:thymidine 5'-triphosphate