Contribution of base excision repair, nucleotide excision repair, and DNA recombination to alkylation resistance of the fission yeast Schizosaccharomyces pombe.
DNA damage is unavoidable, and organisms across the evolutionary spectrum possess DNA repair pathways that are critical for cell viability and genomic stability. To understand the role of base excision repair (BER) in protecting eukaryotic cells against alkylating agents, we generated Schizosaccharomyces pombe strains mutant for the mag1 3-methyladenine DNA glycosylase gene. We report that S. pombe mag1 mutants have only a slightly increased sensitivity to methylation damage, suggesting that Mag1-initiated BER plays a surprisingly minor role in alkylation resistance in this organism. We go on to show that other DNA repair pathways play a larger role than BER in alkylation resistance. Mutations in genes involved in nucleotide excision repair (rad13) and recombinational repair (rhp51) are much more alkylation sensitive than mag1 mutants. In addition, S. pombe mutant for the flap endonuclease rad2 gene, whose precise function in DNA repair is unclear, were also more alkylation sensitive than mag1 mutants. Further, mag1 and rad13 interact synergistically for alkylation resistance, and mag1 and rhp51 display a surprisingly complex genetic interaction. A model for the role of BER in the generation of alkylation-induced DNA strand breaks in S. pombe is discussed.
Memisoglu
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A
Department of Cancer Cell Biology, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Samson
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L
D000225:Adenine / Q000031:analogs & derivatives / Q000378:metabolism; D000477:Alkylating Agents / Q000494:pharmacology*; D004249:DNA Damage; D045647:DNA Glycosylases; D004260:DNA Repair; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial / Q000235:genetics; D004706:Endodeoxyribonucleases; D005656:Fungal Proteins / Q000235:genetics; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008957:Models, Genetic; D009153:Mutagens / Q000494:pharmacology*; D009699:N-Glycosyl Hydrolases / Q000235:genetics*; D051135:Rad51 Recombinase; D011995:Recombination, Genetic; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000187:drug effects* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins; D013045:Species Specificity
D000477:Alkylating Agents; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009153:Mutagens; C084232:RHP51 protein, S pombe; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C073998:RAD2 protein, S cerevisiae; C025946:3-methyladenine; D008741:Methyl Methanesulfonate; D051135:Rad51 Recombinase; D004706:Endodeoxyribonucleases; C021565:3-methyladenine-DNA glycosylase; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D000225:Adenine