Abstract：
DNA double-strand break (DSB) repair is a fundamental cellular process crucial for maintaining genome stability, with homologous recombination and non-homologous end joining as the primary mechanisms, and various alternative pathways such as single-strand annealing (SSA) and microhomology-mediated end joining also playing significant roles under specific conditions. IRC genes were previously identified as part of a group of genes associated with increased levels of Rad52 foci in Saccharomyces cerevisiae. In this study, we investigated the effects of IRC gene mutations on DSB repair, focusing on uncharacterized IRC10, 19, 21, 22, 23, and 24. Gene conversion (GC) assay revealed that irc10Δ, 22Δ, 23Δ, and 24Δ mutants displayed modest increases in GC frequencies, while irc19Δ and irc21Δ mutants exhibited significant reductions. Further investigation revealed that deletion mutations in URA3 were not generated in irc19Δ mutant cells following HO-induced DSBs. Additionally, irc19Δ significantly reduced frequency of SSA, and a synergistic interaction between irc19Δ and rad52Δ was observed in DSB repair via SSA. Assays to determine the choice of DSB repair pathways indicated that Irc19 is necessary for generating both GC and deletion products. Overall, these results suggest a potential role of Irc19 in DSB repair pathways, particularly in end resection process.
摘要：
DNA双链断裂（DSB）修复是维持基因组稳定性至关重要的基本细胞过程，以同源重组和非同源末端连接为主要机制，以及各种替代途径，例如单链退火（SSA）和微同源性介导的末端连接，在特定条件下也起着重要作用。IRC基因先前被鉴定为与酿酒酵母中Rad52病灶水平升高相关的一组基因的一部分。在这项研究中,我们研究了IRC基因突变对DSB修复的影响，重点关注未表征的IRC10、19、21、22、23和24。基因转换(GC)分析显示，irc10Δ，22Δ，23Δ，24Δ突变体显示出GC频率的适度增加，而irc19Δ和irc21Δ突变体表现出显着降低。进一步的研究表明，在HO诱导的DSB后，irc19Δ突变细胞中未产生URA3中的缺失突变。此外,IRC19Δ显著降低SSA的频率，通过SSA在DSB修复中观察到irc19Δ和rad52Δ之间的协同相互作用。确定DSB修复途径的选择的测定表明Irc19对于产生GC和缺失产物都是必需的。总的来说,这些结果表明Irc19在DSB修复途径中的潜在作用，特别是在最终切除过程中。
