Molecular mechanism of Mad2 conformational conversion promoted by the Mad2-interaction motif of Cdc20.

IF 4.5 3区 生物学 Q1 BIOCHEMISTRY & MOLECULAR BIOLOGY
Protein Science Pub Date : 2025-04-01 DOI:10.1002/pro.70099
Conny W H Yu, Elyse S Fischer, Joe G Greener, Jing Yang, Ziguo Zhang, Stefan M V Freund, David Barford
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引用次数: 0

Abstract

During mitosis, unattached kinetochores trigger the spindle assembly checkpoint by promoting the assembly of the mitotic checkpoint complex, a heterotetramer comprising Mad2, Cdc20, BubR1, and Bub3. Critical to this process is the kinetochore-mediated catalysis of an intrinsically slow conformational conversion of Mad2 from an open (O-Mad2) inactive state to a closed (C-Mad2) active state bound to Cdc20. These Mad2 conformational changes involve substantial remodeling of the N-terminal β1 strand and C-terminal β7/β8 hairpin. In vitro, the Mad2-interaction motif (MIM) of Cdc20 (Cdc20MIM) triggers the rapid conversion of O-Mad2 to C-Mad2, effectively removing the kinetic barrier for MCC assembly. How Cdc20MIM directly induces Mad2 conversion remains unclear. In this study, we demonstrate that the Cdc20MIM-binding site is inaccessible in O-Mad2. Time-resolved NMR and molecular dynamics simulations show how Mad2 conversion involves sequential conformational changes of flexible structural elements in O-Mad2, orchestrated by Cdc20MIM. Conversion is initiated by the β7/β8 hairpin of O-Mad2 transiently unfolding to expose a nascent Cdc20MIM-binding site. Engagement of Cdc20MIM to this site promotes the release of the β1 strand. We propose that initial conformational changes of the β7/β8 hairpin allow binding of Cdc20MIM to a transient intermediate state of Mad2, thereby lowering the kinetic barrier to Mad2 conversion.

Cdc20的Mad2相互作用基序促进Mad2构象转化的分子机制。
在有丝分裂过程中,未附着的着丝点通过促进有丝分裂检查点复合体的组装来触发纺锤体组装检查点,这是一种由Mad2、Cdc20、BubR1和Bub3组成的异源四聚体。该过程的关键是着丝酶介导的Mad2从开放(O-Mad2)非活性状态到封闭(C-Mad2)活性状态结合Cdc20的内在缓慢构象转化的催化作用。这些Mad2构象变化涉及n端β1链和c端β7/β8发夹的大量重塑。在体外,Cdc20的mad2相互作用基序(MIM) (Cdc20MIM)触发O-Mad2快速转化为C-Mad2,有效地去除MCC组装的动力学屏障。Cdc20MIM如何直接诱导Mad2转化仍不清楚。在这项研究中,我们证明了cdc20mim结合位点在O-Mad2中是不可访问的。时间分辨核磁共振和分子动力学模拟表明,在Cdc20MIM的协调下,Mad2转化涉及O-Mad2中柔性结构元素的顺序构象变化。转化是由O-Mad2的β7/β8发夹瞬间展开以暴露新生的cdc20mim结合位点开始的。Cdc20MIM与该位点的结合促进了β1链的释放。我们提出,β7/β8发夹的初始构象变化允许Cdc20MIM与Mad2的瞬时中间态结合,从而降低了Mad2转化的动力学屏障。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Protein Science
Protein Science 生物-生化与分子生物学
CiteScore
12.40
自引率
1.20%
发文量
246
审稿时长
1 months
期刊介绍: Protein Science, the flagship journal of The Protein Society, is a publication that focuses on advancing fundamental knowledge in the field of protein molecules. The journal welcomes original reports and review articles that contribute to our understanding of protein function, structure, folding, design, and evolution. Additionally, Protein Science encourages papers that explore the applications of protein science in various areas such as therapeutics, protein-based biomaterials, bionanotechnology, synthetic biology, and bioelectronics. The journal accepts manuscript submissions in any suitable format for review, with the requirement of converting the manuscript to journal-style format only upon acceptance for publication. Protein Science is indexed and abstracted in numerous databases, including the Agricultural & Environmental Science Database (ProQuest), Biological Science Database (ProQuest), CAS: Chemical Abstracts Service (ACS), Embase (Elsevier), Health & Medical Collection (ProQuest), Health Research Premium Collection (ProQuest), Materials Science & Engineering Database (ProQuest), MEDLINE/PubMed (NLM), Natural Science Collection (ProQuest), and SciTech Premium Collection (ProQuest).
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