title: Pathways for Holliday junction processing during homologous recombination in Saccharomyces cerevisiae.
abstract: The Saccharomyces cerevisiae Rmi1 protein is a component of the highly conserved Sgs1-Top3-Rmi1 complex. Deletion of SGS1, TOP3, or RMI1 is synthetically lethal when combined with the loss of the Mus81-Mms4 or Slx1-Slx4 endonucleases, which have been implicated in Holliday junction (HJ) resolution. To investigate the causes of this synthetic lethality, we isolated a temperature-sensitive mutant of the RMI1 strain, referred to as the rmi1-1 mutant. At the restrictive temperature, this mutant phenocopies an rmi1Δ strain but behaves like the wild type at the permissive temperature. Following a transient exposure to methyl methanesulfonate, rmi1-1 mutants accumulate unprocessed homologous recombination repair (HRR) intermediates. These intermediates are slowly resolved at the restrictive temperature, revealing a redundant resolution activity when Rmi1 is impaired. This resolution depends on Mus81-Mms4 but not on either Slx1-Slx4 or another HJ resolvase, Yen1. Similar results were also observed when Top3 function was impaired. We propose that the Sgs1-Top3-Rmi1 complex constitutes the main pathway for the processing of HJ-containing HRR intermediates but that Mus81-Mms4 can also resolve these intermediates.
authors.affiliation: Center for Healthy Aging, Department of Cellular and Molecular Medicine, Panum Institute 18.1, University of Copenhagen, DK-2200 Copenhagen, Denmark.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Ashton
authors.forename: Hocine W
authors.initials: HW
authors.lastname: Mankouri
authors.forename: Anna
authors.initials: A
authors.lastname: Heidenblut
authors.forename: Peter J
authors.initials: PJ
authors.lastname: McHugh
authors.forename: Ian D
authors.initials: ID
authors.lastname: Hickson
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D045566:DNA, Cruciform / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004720:Endonucleases / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D045585:Flap Endonucleases / Q000378:metabolism; D045565:Holliday Junction Resolvases / Q000378:metabolism; D008741:Methyl Methanesulfonate / Q000378:metabolism; D009154:Mutation; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D013696:Temperature
chemical_list: D004269:DNA, Bacterial; D045566:DNA, Cruciform; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C502206:Rmi1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C502374:TOP3 protein, S cerevisiae; D008741:Methyl Methanesulfonate; D004720:Endonucleases; D045585:Flap Endonucleases; C411624:MUS81 protein, S cerevisiae; D045565:Holliday Junction Resolvases; C112057:RusA protein, E coli; C112337:MMS4 protein, S cerevisiae