Sae2 promotes DNA damage resistance by removing the Mre11-Rad50-Xrs2 complex from DNA and attenuating Rad53 signaling
Sae2 promotes DNA damage resistance by removing the Mre11-Rad50-Xrs2 complex from DNA and attenuating Rad53 signaling
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DOI：
10.1073/pnas.1503331112
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发表时间：
2015-04-14
影响因子：
11.1
通讯作者：
Symington, Lorraine S.
中科院分区：
文献类型：
--
作者：
Chen, Huan;Donnianni, Roberto A.;Symington, Lorraine S.
Mre11-Rad50-Xrs2/NBS1 (MRX/N) 核酸酶/ATP 酶复合物在 DNA 双链断裂 (DSB) 修复中发挥结构和催化作用，是 Tel1/ATM 激酶激活的 DNA 损伤传感器。酿酒酵母 Sae2 可以与 MRX 一起启动 5'-3' 末端切除，并且在减弱 DNA 损伤信号传导方面也发挥着重要作用。在这里，我们描述了一类 mre11 等位基因，它通过加速 DNA 末端 Mre11 的周转、关闭 DNA 损伤检查点并允许细胞周期进展来抑制 sae2 Delta 细胞的 DNA 损伤敏感性。 mre11 等位基因不会抑制 sae2 Delta 突变体的末端切除或发夹打开缺陷，表明 Sae2 的这些功能不负责 DNA 损伤抵抗。与野生型 MRX 相比，纯化的 (MRX)-R-P110L 复合物在体外显示出与单链和双链 DNA 的结合减少，这与体内受损位点的 Mre11 周转增加一致。此外，Mre11 的过量产生仅在 Sae2 缺失的情况下才会导致 DNA 损伤敏感性。总之，这些数据表明，未能从 DNA 末端去除 Mre11 并减弱 Rad53 激酶信号传导导致了 sae2 Delta 细胞对断裂剂的超敏反应。
The Mre11-Rad50-Xrs2/NBS1 (MRX/N) nuclease/ATPase complex plays structural and catalytic roles in the repair of DNA double-strand breaks (DSBs) and is the DNA damage sensor for Tel1/ATM kinase activation. Saccharomyces cerevisiae Sae2 can function with MRX to initiate 5'-3' end resection and also plays an important role in attenuation of DNA damage signaling. Here we describe a class of mre11 alleles that suppresses the DNA damage sensitivity of sae2 Delta cells by accelerating turnover of Mre11 at DNA ends, shutting off the DNA damage checkpoint and allowing cell cycle progression. The mre11 alleles do not suppress the end resection or hairpin-opening defects of the sae2 Delta mutant, indicating that these functions of Sae2 are not responsible for DNA damage resistance. The purified (MRX)-R-P110L complex shows reduced binding to single-and double-stranded DNA in vitro relative to wild-type MRX, consistent with the increased turnover of Mre11 from damaged sites in vivo. Furthermore, overproduction of Mre11 causes DNA damage sensitivity only in the absence of Sae2. Together, these data suggest that it is the failure to remove Mre11 from DNA ends and attenuate Rad53 kinase signaling that causes hypersensitivity of sae2 Delta cells to clastogens.