Publication Date:
2011-10-25
Description:
Homologous recombination is a high-fidelity DNA repair pathway. Besides a critical role in accurate chromosome segregation during meiosis, recombination functions in DNA repair and in the recovery of stalled or broken replication forks to ensure genomic stability. In contrast, inappropriate recombination contributes to genomic instability, leading to loss of heterozygosity, chromosome rearrangements and cell death. The RecA/UvsX/RadA/Rad51 family of proteins catalyses the signature reactions of recombination, homology search and DNA strand invasion. Eukaryotes also possess Rad51 paralogues, whose exact role in recombination remains to be defined. Here we show that the Saccharomyces cerevisiae Rad51 paralogues, the Rad55-Rad57 heterodimer, counteract the antirecombination activity of the Srs2 helicase. The Rad55-Rad57 heterodimer associates with the Rad51-single-stranded DNA filament, rendering it more stable than a nucleoprotein filament containing Rad51 alone. The Rad51-Rad55-Rad57 co-filament resists disruption by the Srs2 antirecombinase by blocking Srs2 translocation, involving a direct protein interaction between Rad55-Rad57 and Srs2. Our results demonstrate an unexpected role of the Rad51 paralogues in stabilizing the Rad51 filament against a biologically important antagonist, the Srs2 antirecombination helicase. The biological significance of this mechanism is indicated by a complete suppression of the ionizing radiation sensitivity of rad55 or rad57 mutants by concomitant deletion of SRS2, as expected for biological antagonists. We propose that the Rad51 presynaptic filament is a meta-stable reversible intermediate, whose assembly and disassembly is governed by the balance between Rad55-Rad57 and Srs2, providing a key regulatory mechanism controlling the initiation of homologous recombination. These data provide a paradigm for the potential function of the human RAD51 paralogues, which are known to be involved in cancer predisposition and human disease.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3213327/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3213327/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liu, Jie -- Renault, Ludovic -- Veaute, Xavier -- Fabre, Francis -- Stahlberg, Henning -- Heyer, Wolf-Dietrich -- CA92267/CA/NCI NIH HHS/ -- GM58015/GM/NIGMS NIH HHS/ -- U54 GM074929/GM/NIGMS NIH HHS/ -- U54 GM074929-05/GM/NIGMS NIH HHS/ -- U54GM74929/GM/NIGMS NIH HHS/ -- England -- Nature. 2011 Oct 23;479(7372):245-8. doi: 10.1038/nature10522.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, University of California, Davis, Davis, California 95616-8665, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22020281" target="_blank"〉PubMed〈/a〉
Keywords:
Adenosine Triphosphatases/genetics/*metabolism
;
DNA Helicases/antagonists & inhibitors/*metabolism
;
DNA Repair Enzymes/genetics/*metabolism
;
DNA, Single-Stranded/chemistry/metabolism
;
DNA-Binding Proteins/genetics/*metabolism
;
Protein Binding
;
Rad51 Recombinase/chemistry/*metabolism
;
Saccharomyces cerevisiae/enzymology/genetics/*metabolism
;
Saccharomyces cerevisiae Proteins/antagonists &
;
inhibitors/chemistry/genetics/*metabolism
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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