German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany.
Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077, Göttingen, Germany.
Nat Commun. 2020 Nov 27;11(1):6041. doi: 10.1038/s41467-020-19843-1.
The etiologic agent of the Covid-19 pandemic is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The viral membrane of SARS-CoV-2 surrounds a helical nucleocapsid in which the viral genome is encapsulated by the nucleocapsid protein. The nucleocapsid protein of SARS-CoV-2 is produced at high levels within infected cells, enhances the efficiency of viral RNA transcription, and is essential for viral replication. Here, we show that RNA induces cooperative liquid-liquid phase separation of the SARS-CoV-2 nucleocapsid protein. In agreement with its ability to phase separate in vitro, we show that the protein associates in cells with stress granules, cytoplasmic RNA/protein granules that form through liquid-liquid phase separation and are modulated by viruses to maximize replication efficiency. Liquid-liquid phase separation generates high-density protein/RNA condensates that recruit the RNA-dependent RNA polymerase complex of SARS-CoV-2 providing a mechanism for efficient transcription of viral RNA. Inhibition of RNA-induced phase separation of the nucleocapsid protein by small molecules or biologics thus can interfere with a key step in the SARS-CoV-2 replication cycle.
引发 COVID-19 大流行的病原体是严重急性呼吸系统综合征冠状病毒 2（SARS-CoV-2）。SARS-CoV-2 的病毒膜环绕着一个螺旋核衣壳，其病毒基因组被核衣壳蛋白包裹。SARS-CoV-2 的核衣壳蛋白在感染细胞内高水平产生，提高病毒 RNA 转录的效率，并且对病毒复制至关重要。在这里，我们表明 RNA 诱导 SARS-CoV-2 核衣壳蛋白的合作液-液相分离。与它在体外相分离的能力一致，我们表明该蛋白在细胞中与应激颗粒相关联，应激颗粒是通过液-液相分离形成的细胞质 RNA/蛋白颗粒，并且被病毒调节以最大程度地提高复制效率。液-液相分离产生高浓度的蛋白/RNA 凝聚物，募集 SARS-CoV-2 的 RNA 依赖性 RNA 聚合酶复合物，为病毒 RNA 的有效转录提供了一种机制。因此，小分子或生物制剂抑制核衣壳蛋白的 RNA 诱导相分离可以干扰 SARS-CoV-2 复制周期的关键步骤。
