A conserved Ctp1/CtIP C-terminal peptide stimulates Mre11 endonuclease activity
A conserved Ctp1/CtIP C-terminal peptide stimulates Mre11 endonuclease activity
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保守的 Ctp1/CtIP C 端肽刺激 Mre11 核酸内切酶活性
DOI：
10.1073/pnas.2016287118
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Iwasaki Hiroshi
中科院分区：
文献类型：
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作者：
Zdravkovic Aleksandar;Daley James M.;Dutta Arijit;Niwa Tatsuya;Murayama Yasuto;Kanamaru Shuji;Ito Kentaro;Maki Takahisa;Argunhan Bilge;Takahashi Masayuki;Tsubouchi Hideo;Sung Patrick;Iwasaki Hiroshi
Mre11-Rad50-Nbs1复合体（MRN）在同源重组修复DNA双链断裂（DSBs）中起重要作用。MRN的内切酶活性对于在DSB端切除5 ‘端DNA链，产生3 ’端单链DNA至关重要，这是HR的先决条件。这种内切酶的活性是由ctp激活的，ctp是人ctp的分糖菌同源物。在这里，通过纯化蛋白，我们发现Ctp1磷酸化通过诱导Ctp1与Nbs1的关联来刺激MRN内切酶活性。Ctp1高度保守的末端C对于MRN的激活是必不可少的。重要的是，由Ctp1 C端保守的15个氨基酸组成的多肽（CT15）足以刺激Mre11内切酶活性。此外，来自CtIP的CT15等价物可以刺激人类MRE11内切酶活性，证明了这种刺激机制的普遍性。因此，我们提出nbs1介导的CT15募集在Ctp1/CtIP激活Mre11内切酶中起关键作用。
The Mre11-Rad50-Nbs1 complex (MRN) is important for repairing DNA double-strand breaks (DSBs) by homologous recombination (HR). The endonuclease activity of MRN is critical for resecting 5′-ended DNA strands at DSB ends, producing 3′-ended single-strand DNA, a prerequisite for HR. This endonuclease activity is stimulated by Ctp1, theSchizosaccharomyces pombehomolog of human CtIP. Here, with purified proteins, we show that Ctp1 phosphorylation stimulates MRN endonuclease activity by inducing the association of Ctp1 with Nbs1. The highly conserved extreme C terminus of Ctp1 is indispensable for MRN activation. Importantly, a polypeptide composed of the conserved 15 amino acids at the C terminus of Ctp1 (CT15) is sufficient to stimulate Mre11 endonuclease activity. Furthermore, the CT15 equivalent from CtIP can stimulate human MRE11 endonuclease activity, arguing for the generality of this stimulatory mechanism. Thus, we propose that Nbs1-mediated recruitment of CT15 plays a pivotal role in the activation of the Mre11 endonuclease by Ctp1/CtIP.