Genetic requirements for RAD51- and RAD54-independent break-induced replication repair of a chromosomal double-strand break.
Broken chromosomes can be repaired by several homologous recombination mechanisms, including gene conversion and break-induced replication (BIR). In Saccharomyces cerevisiae, an HO endonuclease-induced double-strand break (DSB) is normally repaired by gene conversion. Previously, we have shown that in the absence of RAD52, repair is nearly absent and diploid cells lose the broken chromosome; however, in cells lacking RAD51, gene conversion is absent but cells can repair the DSB by BIR. We now report that gene conversion is also abolished when RAD54, RAD55, and RAD57 are deleted but BIR occurs, as with rad51Delta cells. DSB-induced gene conversion is not significantly affected when RAD50, RAD59, TID1 (RDH54), SRS2, or SGS1 is deleted. Various double mutations largely eliminate both gene conversion and BIR, including rad51Delta rad50Delta, rad51Delta rad59Delta, and rad54Delta tid1Delta. These results demonstrate that there is a RAD51- and RAD54-independent BIR pathway that requires RAD59, TID1, RAD50, and presumably MRE11 and XRS2. The similar genetic requirements for BIR and telomere maintenance in the absence of telomerase also suggest that these two processes proceed by similar mechanisms.
Department of Biology and Rosenstiel Center, Brandeis University, Waltham, Massachusetts 02254-9110, USA.
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Signon
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Malkova
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Naylor
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Klein
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Haber
D015825:Chromosomes, Fungal; D004247:DNA / Q000235:genetics*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D045643:DNA Repair Enzymes; D004261:DNA Replication / Q000235:genetics; D026942:DNA Topoisomerases; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005785:Gene Conversion; D017353:Gene Deletion; D051135:Rad51 Recombinase; D053484:RecQ Helicases; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase; C530845:HO protein, S cerevisiae; C037725:SCEI protein, S cerevisiae; D015252:Deoxyribonucleases, Type II Site-Specific; C075468:RAD54 protein, S cerevisiae; C090472:SGS1 protein, S cerevisiae; D004265:DNA Helicases; D053484:RecQ Helicases; D026942:DNA Topoisomerases; C541336:RDH54 protein, S cerevisiae; D045643:DNA Repair Enzymes