Roles of SGS1, MUS81, and RAD51 in the repair of lagging-strand replication defects in Saccharomyces cerevisiae

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Yeast cells lacking the SGS1 DNA helicase and the MUS81 structure-specific endonuclease display a synthetic lethality that is suppressed by loss of the RAD51 recombinase. This epistatic interaction suggests that the primary function of SGS1 or MUS81, or both genes, is downstream of RAD51. To identify RAD51-independent functions of SGS1 and MUS81, a synthetic-lethal screen was performed on the sgs1 mus81 rad51 triple mutant. We found that mutation of RNH202, which encodes a subunit of the hetero-trimeric RNase H2, generates a profound synthetic-sickness in this background. RNase H2 is thought to play a non-essential role in Okazaki fragment maturation. Cells lacking RNH202 showed synthetic growth defects when combined with either mus81 or sgs1 alone. But, whereas the loss of RAD51 had little effect on rnh202 sgs1 double mutants, it strongly inhibited the growth of rnh202 mus81 cells. These data indicate that the primary function of SGS1, but not MUS81, is downstream of RAD51. GS1 must have some RAD51-independent function, however, since the growth of rnh202 mus81 rad51 cells was further compromised by the loss of SGS1. Consistent with these results, we show that rnh202 cells display a sensitivity to DNA-damaging agents that is exacerbated in the absence of RAD51 or MUS81. These data support a model in which defects in lagging-strand replication are repaired by the Mus81 endonuclease or through a pathway dependent on Rad51 and Sgs1.

Original languageEnglish (US)
Pages (from-to)213-225
Number of pages13
JournalCurrent Genetics
Issue number4
StatePublished - Oct 2005

All Science Journal Classification (ASJC) codes

  • Genetics


  • DNA repair
  • Mus81
  • Rad51
  • Recombination
  • Sgs1


Dive into the research topics of 'Roles of SGS1, MUS81, and RAD51 in the repair of lagging-strand replication defects in Saccharomyces cerevisiae'. Together they form a unique fingerprint.

Cite this