Homologous Recombination via Synthesis-Dependent Strand Annealing in Yeast Requires the Irc20 and Srs2 DNA Helicases
| Autor: | Kohji Kusano, Takehiko Usui, Masa-Toshi Yamamoto, Hiroaki I. Ogawa, Tohru Miura, Yoshimasa Yamana |
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| Rok vydání: | 2012 |
| Předmět: |
DNA End-Joining Repair
Saccharomyces cerevisiae Proteins DNA repair Saccharomyces cerevisiae Investigations Genetic recombination chemistry.chemical_compound Genetics DNA Breaks Double-Stranded DNA Fungal Homologous Recombination Base Sequence biology DNA Helicases Fungal genetics Helicase RNA Helicase A Molecular biology Rad52 DNA Repair and Recombination Protein Non-homologous end joining enzymes and coenzymes (carbohydrates) chemistry biology.protein Chromosomes Fungal Homologous recombination DNA Plasmids |
| Zdroj: | Genetics. 191:65-78 |
| ISSN: | 1943-2631 |
| DOI: | 10.1534/genetics.112.139105 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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