Structurally distinct Mre11 domains mediate MRX functions in resection, end-tethering and DNA damage resistance
Structurally distinct Mre11 domains mediate MRX functions in resection, end-tethering and DNA damage resistance
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DOI：
10.1093/nar/gky086
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发表时间：
2018-04-06
影响因子：
14.9
通讯作者：
Longhese, Maria Pia
中科院分区：
文献类型：
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作者：
Cassani, Corinne;Gobbini, Elisa;Longhese, Maria Pia
Sae 2与Mre 11-Rad 50-Xrs 2（MRX）复合物合作，启动DNA双链断裂（DSB）的切除，并保持DSB末端非常接近，以允许其修复。这些不同的MRX-Sae 2功能如何有助于DNA损伤抗性尚不清楚。在这里，我们描述了mre 11等位基因，抑制超敏反应的sae 2 δ细胞的遗传毒性剂。通过评估这些突变在细胞和结构水平上的影响，我们发现所有恢复sae 2 Delta对喜树碱和腐草霉素耐药性的mre 11等位基因都会影响Mre 11 N-末端，并通过降低MRX和Tel 1与DSB的关联来抑制sae 2 Delta细胞的切除缺陷。因此，Tel 1持续性的减弱通过降低Rad 9与DSB的结合而增强了Sgs 1-Dna 2切除活性。相比之下，恢复Sae 2 Delta仅对腐草霉素耐药性的mre 11突变位于Mre 11 C末端，并在末端束缚中绕过Sae 2功能，但在DSB切除中不起作用，这可能是通过使Mre 11-Rad 50开放构象不稳定。这些发现揭示了结构上不同的Mre 11结构域的存在，这些结构域通过介导不同的过程来支持对遗传毒性剂的抗性。
Sae2 cooperates with the Mre11-Rad50-Xrs2 (MRX) complex to initiate resection of DNA double-strand breaks (DSBs) and to maintain the DSB ends in close proximity to allow their repair. How these diverse MRX-Sae2 functions contribute to DNA damage resistance is not known. Here, we describe mre11 alleles that suppress the hypersensitivity of sae2 Delta cells to genotoxic agents. By assessing the impact of these mutations at the cellular and structural levels, we found that all the mre11 alleles that restore sae2 Delta resistance to both camptothecin and phleomycin affect the Mre11 N-terminus and suppress the resection defect of sae2 Delta cells by lowering MRX and Tel1 association to DSBs. As a consequence, the diminished Tel1 persistence potentiates Sgs1-Dna2 resection activity by decreasing Rad9 association toDSBs. By contrast, the mre11 mutations restoring sae2 Delta resistance only to phleomycin are located in Mre11 C-terminus and bypass Sae2 function in end-tethering but not in DSB resection, possibly by destabilizing the Mre11-Rad50 open conformation. These findings unmask the existence of structurally distinct Mre11 domains that support resistance to genotoxic agents by mediating different processes.