title: The polymerase eta translesion synthesis DNA polymerase acts independently of the mismatch repair system to limit mutagenesis caused by 7,8-dihydro-8-oxoguanine in yeast.
abstract: Reactive oxygen species are ubiquitous mutagens that have been linked to both disease and aging. The most studied oxidative lesion is 7,8-dihydro-8-oxoguanine (GO), which is often miscoded during DNA replication, resulting specifically in GC --> TA transversions. In yeast, the mismatch repair (MMR) system repairs GO.A mismatches generated during DNA replication, and the polymerase eta (Poleta) translesion synthesis DNA polymerase additionally promotes error-free bypass of GO lesions. It has been suggested that Poleta limits GO-associated mutagenesis exclusively through its participation in the filling of MMR-generated gaps that contain GO lesions. In the experiments reported here, the SUP4-o forward-mutation assay was used to monitor GC --> TA mutation rates in strains defective in MMR (Msh2 or Msh6) and/or in Poleta activity. The results clearly demonstrate that Poleta can function independently of the MMR system to prevent GO-associated mutations, presumably through preferential insertion of cytosine opposite replication-blocking GO lesions. Furthermore, the Poleta-dependent bypass of GO lesions is more efficient on the lagging strand of replication and requires an interaction with proliferating cell nuclear antigen. These studies establish a new paradigm for the prevention of GO-associated mutagenesis in eukaryotes.
authors.affiliation: Department of Molecular Genetics and Microbiology, DUMC Box 3020, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Sarah V
authors.initials: SV
authors.lastname: Mudrak
authors.forename: Caroline
authors.initials: C
authors.lastname: Welz-Voegele
authors.forename: Sue
authors.initials: S
authors.lastname: Jinks-Robertson
mesh_terms: D000483:Alleles; D053843:DNA Mismatch Repair; D004261:DNA Replication; D004271:DNA, Fungal / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D016681:Genome, Fungal / Q000187:drug effects; D006147:Guanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D016296:Mutagenesis; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D000099270:Y-Family DNA Polymerases
chemical_list: D004271:DNA, Fungal; D004259:DNA-Directed DNA Polymerase; D006147:Guanine; D029701:Saccharomyces cerevisiae Proteins; C453560:7,8-dihydro-8-oxoguanine; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases