Infection with coronavirus rearranges the host cell membrane to assemble a replication/transcription complex in which replication of the viral genome and transcription of viral mRNA occur. Although coexistence of nsp3 and nsp4 is known to cause membrane rearrangement, the mechanisms underlying the interaction of these two proteins remain unclear. We demonstrated that binding of nsp4 with nsp3 is essential for membrane rearrangement and identified amino acid residues in nsp4 responsible for the interaction with nsp3. In addition, we revealed that the nsp3-nsp4 interaction is not sufficient to induce membrane rearrangement, suggesting the participation of other factors such as host proteins. Finally, we showed that loss of the nsp3-nsp4 interaction eliminated viral replication by using an infectious cDNA clone and replicon system of SARS-CoV. These findings provide clues to the mechanism of the replication/transcription complex assembly of SARS-CoV and could reveal an antiviral target for the treatment of betacoronavirus infection.

冠状病毒感染会重新排列宿主细胞膜，以组装复制/转录复合体，在其中发生病毒基因组的复制和病毒mRNA的转录。尽管已知nsp3和nsp4的共存会引起膜重排，但尚不清楚这两种蛋白相互作用的潜在机制。我们证明了nsp4与nsp3的结合对于膜重排是必不可少的，并确定了nsp4中负责与nsp3相互作用的氨基酸残基。此外，我们发现nsp3-nsp4相互作用不足以诱导膜重排，表明其他因素（例如宿主蛋白）的参与。最后，我们表明，通过使用SARS-CoV的感染性cDNA克隆和复制子系统，nsp3-nsp4相互作用的丧失消除了病毒复制。