BLM Ortholog, Sgs1, Prevents Aberrant Crossing-over by Suppressing Formation of Multichromatid Joint Molecules

Steve D. Oh, Jessica P. Lao, Patty Yi Hwa Hwang, Andrew F. Taylor, Gerald R. Smith, Neil Hunter

Research output: Contribution to journalArticle

192 Scopus citations

Abstract

Bloom's helicase (BLM) is thought to prevent crossing-over during DNA double-strand-break repair (DSBR) by disassembling double-Holliday junctions (dHJs) or by preventing their formation. We show that the Saccharomyces cerevisiae BLM ortholog, Sgs1, prevents aberrant crossing-over during meiosis by suppressing formation of joint molecules (JMs) comprising three and four interconnected duplexes. Sgs1 and procrossover factors, Msh5 and Mlh3, are antagonistic since Sgs1 prevents dHJ formation in msh5 cells and sgs1 mutation alleviates crossover defects of both msh5 and mlh3 mutants. We propose that differential activity of Sgs1 and procrossover factors at the two DSB ends effects productive formation of dHJs and crossovers and prevents multichromatid JMs and counterproductive crossing-over. Strand invasion of different templates by both DSB ends may be a common feature of DSBR that increases repair efficiency but also the likelihood of associated crossing-over. Thus, by disrupting aberrant JMs, BLM-related helicases maximize repair efficiency while minimizing the risk of deleterious crossing-over.

Original languageEnglish (US)
Pages (from-to)259-272
Number of pages14
JournalCell
Volume130
Issue number2
DOIs
StatePublished - Jul 27 2007

Keywords

  • DNA
  • PROTEINS

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology

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