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研究揭示SARS-CoV-2突刺蛋白介导的受体结合和活化
2020-09-21 23:06

英国弗朗西斯·克里克研究所Steven J. Gamblin等研究人员合作揭示了SARS-CoV-2突刺蛋白介导的受体结合和活化。相关论文于2020年9月17日在线发表于国际学术期刊《自然》。

研究人员表示,SARS-CoV-2感染是由病毒与ACE2细胞表面受体结合而引发的,然后病毒与细胞膜融合后将病毒基因组释放到细胞中。受体结合和膜融合活性均由病毒突刺糖蛋白S介导。与其他I类膜融合蛋白一样,S在翻译后被弗林蛋白酶切割成S1和S2组分,这些组分在切割后仍保持关联。受体结合后的融合激活被认为涉及暴露第二个蛋白水解位点(S2’),其切割是融合肽释放所必需的。
 
研究人员通过冷冻电镜揭示了ACE2与SARS-CoV-2 S的弗林蛋白酶切割形式的结合。研究人员对十个不同的分子种类进行了分类,包括未结合的、封闭的突刺三聚体、完全开放的ACE2结合三聚体以及与ACE2结合的解离单体S1。十个结构描述了ACE2结合事件,该事件使突刺三聚体不稳定,进而逐渐打开和释放单个S1组分。开放过程减少了S1的接触并解除了三聚体S2核的保护,引发了ACE2结合的S1单体的融合活化和解离。
 
该结构还揭示了ACE2结合后S1亚结构域的重折叠,从而破坏了与S2的相互作用,特别是Asp614的相互作用,最终导致邻近二级(S2')切割位点的S2结构不稳定。
 
附:英文原文

Title: Receptor binding and priming of the spike protein of SARS-CoV-2 for membrane fusion

Author: Donald J. Benton, Antoni G. Wrobel, Pengqi Xu, Chlo Roustan, Stephen R. Martin, Peter B. Rosenthal, John J. Skehel, Steven J. Gamblin

Issue&Volume: 2020-09-17

Abstract: SARS-CoV-2 infection is initiated by virus binding to ACE2 cell surface receptors1–4, followed by fusion of virus and cell membranes to release the virus genome into the cell. Both receptor binding and membrane fusion activities are mediated by the virus Spike glycoprotein, S5–7. As with other class I membrane fusion proteins, S is post-translationally cleaved, in this case by furin, into S1 and S2 components that remain associated following cleavage8–10. Fusion activation following receptor binding is proposed to involve the exposure of a second proteolytic site (S2’), cleavage of which is required for the fusion peptide release11,12. We have investigated the binding of ACE2 to the furin-cleaved form of SARS-CoV-2 S by cryoEM. We classify ten different molecular species including the unbound, closed spike trimer, the fully open ACE2-bound trimer, and dissociated monomeric S1 bound to ACE2. The ten structures describe ACE2 binding events which destabilise the spike trimer, progressively opening up, and out, the individual S1 components. The opening process reduces S1 contacts and un-shields the trimeric S2 core, priming fusion activation and dissociation of ACE2-bound S1 monomers. The structures also reveal refolding of an S1 subdomain following ACE2 binding, that disrupts interactions with S2, notably involving Asp61413–15, leading to destabilisation of the structure of S2 proximal to the secondary (S2’) cleavage site.

DOI: 10.1038/s41586-020-2772-0

Source: https://www.nature.com/articles/s41586-020-2772-0

Nature:《自然》,创刊于1869年。隶属于施普林格·自然出版集团,最新IF:69.504
官方网址:http://www.nature.com/
投稿链接:http://www.nature.com/authors/submit_manuscript.html


本期文章:《自然》:Online/在线发表

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