title: UV-induced T-->C transition at a TT photoproduct site is dependent on Saccharomyces cerevisiae polymerase eta in vivo.
abstract: UV-induced reversion of the arg4-17 ochre allele in Saccharomyces cerevisiae is largely dependent on translesion polymerase eta (Rad30p), known to bypass cyclobutane-type TT dimers in an error-free fashion. arg4-17 locus reversion was predominantly due to T-->C transition of T127, the 3' T of a TT photoproduct site. This event was at least 20-fold reduced in a rad30 deletion mutant, irrespective of the status of nucleotide excision repair. These data correlate with known properties of 6-4 TT photoproducts and in vitro characteristics of polymerase eta and suggest that polymerase eta plays an important in vivo role in inserting G opposite the 3' T of 6-4 TT photoproducts at this site. Alternatively, an unprecedented error-prone processing of cyclobutane-type photoproducts at this site by polymerase eta must be assumed as the critical mechanism. Whereas photoreactivation results indeed hint at the latter possibility, a possible regulatory influence of reducing the overall UV damage load on the bypass probability of non-cyclobutane-type pyrimidine dimer photoproducts should not be dismissed.
authors.affiliation: Department of Radiation Oncology and Winship Cancer Institute, B5111, Emory University School of Medicine, 1365 B Clifton Road NE, Atlanta, GA 30322, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Wolfram
authors.initials: W
authors.lastname: Siede
mesh_terms: D001123:Argininosuccinate Lyase; D001483:Base Sequence; D002455:Cell Division / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair; D004271:DNA, Fungal / Q000737:chemistry; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000502:physiology*; D003845:Deoxycytosine Nucleotides / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D005656:Fungal Proteins / Q000235:genetics; D009154:Mutation; D009690:Nucleic Acid Conformation; D011740:Pyrimidine Dimers / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D029701:Saccharomyces cerevisiae Proteins; D013942:Thymine Nucleotides / Q000378:metabolism; D014466:Ultraviolet Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D001123:Argininosuccinate Lyase; D004271:DNA, Fungal; D004259:DNA-Directed DNA Polymerase; D003845:Deoxycytosine Nucleotides; D005656:Fungal Proteins; D011740:Pyrimidine Dimers; D029701:Saccharomyces cerevisiae Proteins; D013942:Thymine Nucleotides; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases; C087900:Arg4 protein, S cerevisiae