title: DNA polymerases beta and lambda bypass thymine glycol in gapped DNA structures.
abstract: Here we investigated the ability of the human X-family DNA polymerases beta and lambda to bypass thymine glycol (Tg) in gapped DNA substrates with the damage located in a defined position of the template strand. Maximum velocities and the Michaelis constant values were determined to study DNA synthesis in the presence of either Mg(2+) or Mn(2+). Additionally, the influence of hRPA (human replication protein A) and hPCNA (human proliferating cell nuclear antigen) on TLS (translesion synthesis) activity of DNA polymerases beta and lambda was examined. The results show that (i) DNA polymerase lambda is able to catalyze DNA synthesis across Tg, (ii) the ability of DNA polymerase lambda to elongate from a base paired to a Tg lesion is influenced by the size of the DNA gap, (iii) hPCNA increases the fidelity of Tg bypass and does not influence normal DNA synthesis catalyzed by DNA polymerase lambda, (iv) DNA polymerase beta catalyzes the incorporation of all four dNTPs opposite Tg, and (v) hPCNA as well as hRPA has no specific effect on TLS in comparison with the normal DNA synthesis catalyzed by DNA polymerase beta. These results considerably extend our knowledge concerning the ability of specialized DNA polymerases to cope with a very common DNA lesion such as Tg.
authors.affiliation: Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk, Russia.
authors.forename: Ekaterina A
authors.initials: EA
authors.lastname: Belousova
authors.forename: Giovanni
authors.initials: G
authors.lastname: Maga
authors.forename: Yang
authors.initials: Y
authors.lastname: Fan
authors.forename: Elena A
authors.initials: EA
authors.lastname: Kubareva
authors.forename: Elena A
authors.initials: EA
authors.lastname: Romanova
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Lebedeva
authors.forename: Tatiana S
authors.initials: TS
authors.lastname: Oretskaya
authors.forename: Olga I
authors.initials: OI
authors.lastname: Lavrik
mesh_terms: D020029:Base Pairing / Q000235:genetics; D002384:Catalysis; D004249:DNA Damage / Q000235:genetics*; D019951:DNA Polymerase beta / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D004260:DNA Repair / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D006801:Humans; D005810:Multigene Family; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry; D051716:Replication Protein A / Q000737:chemistry; D013379:Substrate Specificity / Q000235:genetics; D013698:Templates, Genetic; D013941:Thymine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000633:toxicity
chemical_list: D018809:Proliferating Cell Nuclear Antigen; C497167:RPA1 protein, human; D051716:Replication Protein A; C029389:thymine glycol; C415367:DNA polymerase beta2; D019951:DNA Polymerase beta; D013941:Thymine