Structural basis of human separase regulation by securin and CDK1-cyclin B1.
Structural basis of human separase regulation by securin and CDK1-cyclin B1.
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DOI：
10.1038/s41586-021-03764-0
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发表时间：
2021-08
期刊：
影响因子：
64.8
通讯作者：
Boland A
中科院分区：
文献类型：
--
作者：
Yu J;Raia P;Ghent CM;Raisch T;Sadian Y;Cavadini S;Sabale PM;Barford D;Raunser S;Morgan DO;Boland A
在有丝分裂早期，复制的染色体通过环状的黏连蛋白复合体结合在一起。分裂后期的染色体分离是由分离酶触发的，分离酶是一种大的半胱氨酸内肽酶，可以切割粘着蛋白亚基Scc 1/Rad 21。分离酶通过降解其抑制剂securin和cyclin B而被激活，但分离酶调节的分子机制尚不清楚。在这里，我们使用低温电子显微镜（cryoEM），以确定与securin或Cdk 1-cyclin B1-Cks 1复合的人分离酶的结构。在这两个复合物中，分离酶被抑制的pseudosubstrate图案，阻止基板结合在活性位点和附近的对接网站。与秀丽隐杆线虫和酵母一样，人类securin也有自己的假底物基序。与此相反，Cdk 1-细胞周期蛋白B1抑制分离酶通过部署从分离酶本身的内在无序循环的伪底物基序。一个自抑制环由Cdk 1-cyclin B1定向以阻断分离酶和Cdk 1的活性位点。另一个自抑制环阻断底物在分离酶催化位点附近的裂缝中对接。第三个分离酶环含有一个磷酸丝氨酸，通过与细胞周期蛋白B1中保守的磷酸结合口袋结合来促进复合物的组装。我们的研究揭示了securin和Cdk 1-cyclin B1结合和抑制分离酶的多种机制，为染色体分离的鲁棒控制提供了分子基础。
In early mitosis, the duplicated chromosomes are held together by the ring-shaped cohesin complex. Chromosome separation in anaphase is triggered by separase, a large cysteine endopeptidase that cleaves the cohesin subunit Scc1/Rad21. Separase is activated by degradation of its inhibitors securin and cyclin B, but the molecular mechanisms of separase regulation are not clear. Here, we used cryogenic electron microscopy (cryoEM) to determine the structures of human separase in complex with either securin or Cdk1-cyclin B1-Cks1. In both complexes, separase is inhibited by pseudosubstrate motifs that block substrate binding at the active site and at nearby docking sites. As in Caenorhabditis elegans and yeast, human securin harbors its own pseudosubstrate motifs. In contrast, Cdk1-cyclin B1 inhibits separase by deploying pseudosubstrate motifs from intrinsically disordered loops in separase itself. One autoinhibitory loop is oriented by Cdk1-cyclin B1 to block the active sites of both separase and Cdk1. Another autoinhibitory loop blocks substrate docking in a cleft adjacent to the separase catalytic site. A third separase loop contains a phosphoserine that promotes complex assembly by binding to a conserved phosphate-binding pocket in cyclin B1. Our study reveals the diverse array of mechanisms by which securin and Cdk1-cyclin B1 bind and inhibit separase, providing the molecular basis for the robust control of chromosome segregation.
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影响因子：
48
作者：
Kucukelbir, Alp;Sigworth, Fred J.;Tagare, Hemant D.
通讯作者：
Tagare, Hemant D.
影响因子：
16.8
作者：
Boland A;Martin TG;Zhang Z;Yang J;Bai XC;Chang L;Scheres SH;Barford D
通讯作者：
Barford D
DOI：
10.1107/s2059798318009324
发表时间：
2018-09-01
期刊：
Acta crystallographica. Section D, Structural biology
影响因子：
--
作者：
Afonine PV;Klaholz BP;Moriarty NW;Poon BK;Sobolev OV;Terwilliger TC;Adams PD;Urzhumtsev A
通讯作者：
Urzhumtsev A
影响因子：
16.8
作者：
Koivomaegi, Mardo;Oerd, Mihkel;Iofik, Anna;Valk, Ervin;Venta, Rainis;Faustova, Ilona;Kivi, Rait;Balog, Eva Rose M.;Rubin, Seth M.;Loog, Mart
通讯作者：
Loog, Mart
影响因子：
64.5
作者：
Ciosk, R;Zachariae, W;Nasmyth, K
通讯作者：
Nasmyth, K