Analysis of MRE11's function in the 5′→3′ processing of DNA double-strand breaks
Analysis of MRE11's function in the 5′→3′ processing of DNA double-strand breaks
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DOI：
10.1093/nar/gks044
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发表时间：
2012-05-01
影响因子：
14.9
通讯作者：
Yan，Hong
中科院分区：
文献类型：
--
作者：
Liao，Shuren;Guay，Catherine;Yan，Hong
DNA双链断裂（DSB）被切除为3′单链尾是同源依赖性修复途径的起始步骤。在这个过程中的一个关键球员是MRE 11-RAD 50-NBS 1复合物，但其在切除中的贡献和机制作用还没有得到很好的理解。在本研究中，我们利用Xenopusegg提取系统来解决这些问题。我们发现，MRE 11的缺失导致了对5′-切除的显著抑制，即使是5′-末端的第一个核苷酸。XenopusCtIP的耗竭也抑制5′-链切除，但这种抑制作用可被过量的MRN减轻。MRE 11和CtIP都可以被带有3′-ss-尾的DNA绕过。最后，使用纯化的蛋白质，我们发现MRN可以刺激WRN-DNA 2-RPA途径和EXO 1途径的切除。这些发现为MRE 11在5′-链切除中的功能提供了重要的见解。
The resection of DNA double-strand breaks (DSBs) into 3′ single-strand tails is the initiating step of homology-dependent repair pathways. A key player in this process is the MRE11-RAD50-NBS1 complex, but its contribution to and mechanistic role in resection are not well understood. In this study, we took advantage of theXenopusegg extract system to address these questions. We found that depletion of MRE11 caused a dramatic inhibition of 5′-resection, even for the first nucleotide at the 5′-end. Depletion ofXenopusCtIP also inhibited 5′-strand resection, but this inhibition could be alleviated by excess MRN. Both MRE11 and CtIP could be bypassed by a DNA that carried a 3′-ss-tail. Finally, using purified proteins, we found that MRN could stimulate both the WRN-DNA2-RPA pathway and the EXO1 pathway of resection. These findings provide important insights into the function of MRE11 in 5′-strand resection.