Effect of DNA polymerases and high mobility group protein 1 on the carrierligand specificity for translesion synthesis past platinum-DNA adducts

Translesion synthesis past Pt-DNA adducts can affect both the cytotoxicity and mutagenicity of the platinum adducts, We have shown previously that the extent of replicative bypass in vivo is influenced by the carrier ligand o f platinum adducts. The specificity of replicative bypass may be determined by the DNA polymerase complexes that catalyze translesion synthesis past P t-DNA adducts and/or by DNA damage-recognition proteins that bind to the Pt -DNA adducts and block translesion replication. In the present study, prime r extension on DNA templates containing site-specifically placed cisplatin. oxaliplatin. JM216; or chlorodiethylenetriamine-Pt adducts revealed that t he eukaryotic DNA polymerases beta, zeta, gamma, and human immunodeficiency virus type I reverse transcriptase (HIV-I RT) had a similar specificity fo r translesion synthesis past Pt-DNA adducts (dien much greater than oxalipl atin greater than or equal to cisplatin > JM316). Primer extension assays p erformed in the presence of high mobility group protein 1 (HMG 1), which is known to recognize cisplatin-damaged DNA, revealed that inhibition of tran slesion synthesis by HMG1 also depended on the carrier ligand of the Pt-DNA adduct (cisplatin > oxaliplarin = JM216 much greater than dien), These dat a were consistent with the results of gel-shift experiments showing similar differences in the affinity of HMG1 For DNA modified with the different pl atinum adducts. Our studies show that both DNA polymerases and damage recog nition proteins can impart specificity to replicative bypass of Pt-DNA addu cts. This information may serve as a model for further studies of translesi on synthesis.