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PMID:22367032

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Citation

Miura, T, Yamana, Y, Usui, T, Ogawa, HI, Yamamoto, MT and Kusano, K (2012) Homologous recombination via synthesis-dependent strand annealing in yeast requires the Irc20 and Srs2 DNA helicases. Genetics 191:65-78

Abstract

Synthesis-dependent strand-annealing (SDSA)-mediated homologous recombination replaces the sequence around a DNA double-strand break (DSB) with a copy of a homologous DNA template, while maintaining the original configuration of the flanking regions. In somatic cells at the 4n stage, Holliday-junction-mediated homologous recombination and nonhomologous end joining (NHEJ) cause crossovers (CO) between homologous chromosomes and deletions, respectively, resulting in loss of heterozygosity (LOH) upon cell division. However, the SDSA pathway prevents DSB-induced LOH. We developed a novel yeast DSB-repair assay with two discontinuous templates, set on different chromosomes, to determine the genetic requirements for somatic SDSA and precise end joining. At first we used our in vivo assay to verify that the Srs2 helicase promotes SDSA and prevents imprecise end joining. Genetic analyses indicated that a new DNA/RNA helicase gene, IRC20, is in the SDSA pathway involving SRS2. An irc20 knockout inhibited both SDSA and CO and suppressed the srs2 knockout-induced crossover enhancement, the mre11 knockout-induced inhibition of SDSA, CO, and NHEJ, and the mre11-induced hypersensitivities to DNA scissions. We propose that Irc20 and Mre11 functionally interact in the early steps of DSB repair and that Srs2 acts on the D-loops to lead to SDSA and to prevent crossoverv.

Links

PubMed PMC3338270 Online version:10.1534/genetics.112.139105

Keywords

Base Sequence; Chromosomes, Fungal/genetics; Chromosomes, Fungal/metabolism; DNA Breaks, Double-Stranded; DNA End-Joining Repair/genetics; DNA Helicases/metabolism; DNA, Fungal/biosynthesis; DNA, Fungal/genetics; DNA, Fungal/metabolism; Homologous Recombination; Plasmids/genetics; Rad52 DNA Repair and Recombination Protein/metabolism; Saccharomyces cerevisiae/enzymology; Saccharomyces cerevisiae/genetics; Saccharomyces cerevisiae/metabolism; Saccharomyces cerevisiae Proteins/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

YEAST:IRC20

involved_in

GO:0006303: double-strand break repair via nonhomologous end joining

ECO:0000316: genetic interaction evidence used in manual assertion

UniProtKB:P32829

P

Seeded From UniProt

complete

YEAST:IRC20

involved_in

GO:0045003: double-strand break repair via synthesis-dependent strand annealing

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

YEAST:IRC20

involved_in

GO:0045003: double-strand break repair via synthesis-dependent strand annealing

ECO:0000316: genetic interaction evidence used in manual assertion

SGD:S000003628

P

Seeded From UniProt

complete


See also

References

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