Suppression of genetic defects within the RAD6 pathway by srs2 is specific for error-free post-replication repair but not for damage-induced mutagenesis

Nucleic Acids Res. 2002 Feb 1;30(3):732-9. doi: 10.1093/nar/30.3.732.

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

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases*
  • Cell Division / drug effects
  • Cell Division / radiation effects
  • DNA Damage / drug effects
  • DNA Damage / genetics*
  • DNA Damage / radiation effects
  • DNA Helicases / genetics
  • DNA Helicases / metabolism*
  • DNA Repair / genetics*
  • DNA Replication / drug effects
  • DNA Replication / radiation effects
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / metabolism
  • Epistasis, Genetic
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Kinetics
  • Ligases / metabolism*
  • Methyl Methanesulfonate / pharmacology
  • Mutagenesis / drug effects
  • Mutagenesis / genetics*
  • Mutagenesis / radiation effects
  • Phenotype
  • Radiation Tolerance / genetics
  • Recombination, Genetic / drug effects
  • Recombination, Genetic / genetics
  • Recombination, Genetic / radiation effects
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / radiation effects
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Substrate Specificity
  • Suppression, Genetic / genetics*
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitin-Protein Ligases
  • Ultraviolet Rays

Substances

  • Fungal Proteins
  • MMS2 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • SRS2 protein, S cerevisiae
  • Methyl Methanesulfonate
  • RAD6 protein, S cerevisiae
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitin-Protein Ligases
  • DNA-Directed DNA Polymerase
  • REV3 protein, S cerevisiae
  • Adenosine Triphosphatases
  • RAD5 protein, S cerevisiae
  • DNA Helicases
  • Ligases