Abstract
srs2 was isolated during a screen for mutants that could suppress the UV-sensitive phenotype of rad6 and rad18 cells. Genetic analyses led to a proposal that Srs2 acts to prevent the channeling of DNA replication-blocking lesions into homologous recombination. The phenotypes associated with srs2 indicate that the Srs2 protein acts to process lesions through RAD6-mediated post-replication repair (PRR) rather than recombination repair. The RAD6 pathway has been divided into three rather independent subpathways: two error-free (represented by RAD5 and POL30) and one error-prone (represented by REV3). In order to determine on which subpathways Srs2 acts, we performed comprehensive epistasis analyses; the experimental results indicate that the srs2 mutation completely suppresses both error-free PRR branches. Combined with UV-induced mutagenesis assays, we conclude that the Polzeta-mediated error-prone pathway is functional in the absence of Srs2; hence, Srs2 is not required for mutagenesis. Furthermore, we demonstrate that the helicase activity of Srs2 is probably required for the phenotypic suppression of error-free PRR defects. Taken together, our observations link error-free PRR to homologous recombination through the helicase activity of Srs2.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine Triphosphatases*
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Cell Division / drug effects
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Cell Division / radiation effects
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DNA Damage / drug effects
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DNA Damage / genetics*
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DNA Damage / radiation effects
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DNA Helicases / genetics
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DNA Helicases / metabolism*
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DNA Repair / genetics*
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DNA Replication / drug effects
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DNA Replication / radiation effects
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DNA-Directed DNA Polymerase / genetics
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DNA-Directed DNA Polymerase / metabolism
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Epistasis, Genetic
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Fungal Proteins / genetics
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Fungal Proteins / metabolism
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Kinetics
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Ligases / metabolism*
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Methyl Methanesulfonate / pharmacology
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Mutagenesis / drug effects
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Mutagenesis / genetics*
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Mutagenesis / radiation effects
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Phenotype
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Radiation Tolerance / genetics
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Recombination, Genetic / drug effects
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Recombination, Genetic / genetics
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Recombination, Genetic / radiation effects
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Saccharomyces cerevisiae / drug effects
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae / radiation effects
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism
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Substrate Specificity
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Suppression, Genetic / genetics*
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Ubiquitin-Conjugating Enzymes
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Ubiquitin-Protein Ligases
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Ultraviolet Rays
Substances
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Fungal Proteins
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MMS2 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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SRS2 protein, S cerevisiae
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Methyl Methanesulfonate
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RAD6 protein, S cerevisiae
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Ubiquitin-Conjugating Enzymes
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Ubiquitin-Protein Ligases
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DNA-Directed DNA Polymerase
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REV3 protein, S cerevisiae
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Adenosine Triphosphatases
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RAD5 protein, S cerevisiae
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DNA Helicases
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Ligases