Abstract：
Upon entering host cells, β-coronaviruses specifically induce generation of replication organelles (ROs) from the endoplasmic reticulum (ER) through their nonstructural protein 3 (nsp3) and nsp4 for viral genome transcription and replication. The most predominant ROs are double-membrane vesicles (DMVs). The ER-resident proteins VMP1 and TMEM41B, which form a complex to regulate autophagosome and lipid droplet (LD) formation, were recently shown to be essential for β-coronavirus infection. Here we report that VMP1 and TMEM41B contribute to DMV generation but function at different steps. TMEM41B facilitates nsp3-nsp4 interaction and ER zippering, while VMP1 is required for subsequent closing of the paired ER into DMVs. Additionally, inhibition of phosphatidylserine (PS) formation by siPTDSS1 partially reverses the DMV and LD defects in VMP1 KO cells, suggesting that appropriate PS levels also contribute to DMV formation. This work provides clues to the mechanism of how host proteins collaborate with viral proteins for endomembrane reshaping to promote viral infection.
摘要：
进入宿主细胞后,β-冠状病毒通过其非结构蛋白3（nsp3）和nsp4特异性诱导内质网（ER）产生复制细胞器（RO），用于病毒基因组转录和复制。最主要的RO是双膜囊泡(DMV)。ER驻留蛋白VMP1和TMEM41B，形成一个复合物来调节自噬小体和脂滴（LD）的形成，最近被证明对β-冠状病毒感染至关重要。在这里，我们报告VMP1和TMEM41B有助于DMV的产生，但在不同的步骤起作用。TMEM41B促进nsp3-nsp4交互和ER拉链，而随后将成对的ER关闭到DMV中需要VMP1。此外,通过siPTDSS1抑制磷脂酰丝氨酸（PS）的形成部分逆转了VMP1KO细胞中的DMV和LD缺陷，表明适当的PS水平也有助于DMV的形成。这项工作为宿主蛋白如何与病毒蛋白合作进行内膜重塑以促进病毒感染的机制提供了线索。
