Srs2 and RecQ homologs cooperate in mei-3-mediated homologous recombination repair of Neurospora crassa

Nucleic Acids Res. 2005 Mar 30;33(6):1848-58. doi: 10.1093/nar/gki326. Print 2005.

Abstract

Homologous recombination and post-replication repair facilitate restart of stalled or collapsed replication forks. The SRS2 gene of Saccharomyces cerevisiae encodes a 3'-5' DNA helicase that functions both in homologous recombination repair and in post-replication repair. This study identifies and characterizes the SRS2 homolog in Neurospora crassa, which we call mus-50. A knockout mutant of N.crassa, mus-50, is sensitive to several DNA-damaging agents and genetic analyses indicate that it is epistatic with mei-3 (RAD51 homolog), mus-11 (RAD52 homolog), mus-48 (RAD55 homolog) and mus-49 (RAD57 homolog), suggesting a role for mus-50 in homologous recombination repair. However, epistasis evidence has presented that MUS50 does not participate in post-replication repair in N.crassa. Also, the N.crassa mus-25 (RAD54 homolog) mus-50 double mutant is viable, which is in contrast to the lethal phenotype of the equivalent rad54 srs2 mutant in S.cerevisiae. Tetrad analysis revealed that mus-50 in combination with mutations in two RecQ homologs, qde-3 and recQ2, is lethal, and this lethality is suppressed by mutation in mei-3, mus-11 or mus-25. Evidence is also presented for the two independent pathways for recovery from camptothecin-induced replication fork arrest: one pathway is dependent on QDE3 and MUS50 and the other pathway is dependent on MUS25 and RECQ2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA Helicases / genetics
  • DNA Helicases / physiology*
  • DNA Repair*
  • Epistasis, Genetic
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Fungal Proteins / physiology*
  • Genes, Lethal
  • Methyl Methanesulfonate / toxicity
  • Mutation
  • Neurospora crassa / drug effects
  • Neurospora crassa / enzymology
  • Neurospora crassa / genetics*
  • Recombination, Genetic
  • Suppression, Genetic

Substances

  • Fungal Proteins
  • MEI-3 protein, Neurospora crassa
  • Methyl Methanesulfonate
  • DNA Helicases
  • QDE-3 protein, Neurospora crassa