Long-range DNA end resection supports homologous recombination by checkpoint activation rather than extensive homology generation.
Long-range DNA end resection supports homologous recombination by checkpoint activation rather than extensive homology generation.
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DOI：
10.7554/elife.84322
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发表时间：
2023-06-30
期刊：
影响因子：
7.7
通讯作者：
Symington LS
中科院分区：
文献类型：
--
作者：
Kimble MT;Johnson MJ;Nester MR;Symington LS
同源重组（HR）是一种高保真的双链断裂（DSB）修复机制，它依赖于DNA末端的5′-末端的溶核降解。然而，由Exo 1和/或Sgs 1-Dna 2介导的长距离切除在HR中的作用尚未完全了解。在这里，我们表明，Exo 1和Sgs 1是紧密相连的重复序列之间的重组，但需要在酿酒酵母染色体间的重复重组。这种对长距离末端切除的背景特异性要求与其在激活DNA损伤检查点中的作用有关。与此作用一致，检查点突变体也显示出特异性染色体间重组的缺陷。此外，检查点的人工激活部分恢复染色体间重组到exo 1 sgs 1 sg细胞。然而，细胞周期延迟是不足以挽救exo 1 bisgs 1 bisg鉴于检查点是必要的DNA损伤诱导的染色体移动性，我们建议，检查点的重要性，因此长距离切除，在染色体间重组是由于需要增加染色体的流动性，以促进配对的遥远的网站。当DSB及其修复模板非常接近时，可以避免远距离切除的需要。
Homologous recombination (HR), the high-fidelity mechanism for double-strand break (DSB) repair, relies on DNA end resection by nucleolytic degradation of the 5′-terminated ends. However, the role of long-range resection mediated by Exo1 and/or Sgs1-Dna2 in HR is not fully understood. Here, we show that Exo1 and Sgs1 are dispensable for recombination between closely linked repeats, but are required for interchromosomal repeat recombination in Saccharomyces cerevisiae. This context-specific requirement for long-range end resection is connected to its role in activating the DNA damage checkpoint. Consistent with this role, checkpoint mutants also show a defect specifically in interchromosomal recombination. Furthermore, artificial activation of the checkpoint partially restores interchromosomal recombination to exo1∆ sgs1∆ cells. However, cell cycle delay is insufficient to rescue the interchromosomal recombination defect of exo1∆ sgs1∆ cells, suggesting an additional role for the checkpoint. Given that the checkpoint is necessary for DNA damage-induced chromosome mobility, we propose that the importance of the checkpoint, and therefore long-range resection, in interchromosomal recombination is due to a need to increase chromosome mobility to facilitate pairing of distant sites. The need for long-range resection is circumvented when the DSB and its repair template are in close proximity.