Understanding of viral replication through the interaction with coronavirus nsp1 and host proteins

严重急性呼吸综合征冠状病毒（SARS CoV）是一种新型的疾病的病原体。Nsp 1与40 S核糖体亚基结合，这导致表达Nsp 1的细胞中的翻译关闭。nsp 1 - 40 S复合物进一步诱导宿主mRNA的5 'UTR附近的核酸内切RNA切割，导致RNA降解的促进。然而，nsp 1诱导RNA切割的机制尚不清楚。我们确定Upf 1作为结合伴侣的nsp 1的下拉纯化和质谱。Upf 1是一种主要与细胞质RNA结合的蛋白，在无义介导的RNA降解途径中起重要作用。转染细胞中的免疫共沉淀分析证实了nsp 1和Upf 1之间的特异性相互作用。小干扰RNA介导的Upf 1敲低导致抑制nsp 1介导的RNA切割。我们的数据表明了一种新的机制，宿主mRNA切割SARA-CoV nsp 1蛋白。

Severe acute respiratory syndrome coronavirus (SARS-CoV) is the etiological agent of a newly emerged disease. Nsp1 binds to 40S ribosome subunits, which causes a translational shutoff in the cells expressing nsp1. The nsp1-40S complex further induces an endonucleolytic RNA cleavage near the 5'UTR of host mRNA, resulting in the promotion of RNA decay. However, the mechanism by which nsp1-induced RNA cleavage is unknown. We identified Upf1 as a binding partner of nsp1 by pulldown purification and mass spectrometry. Upf1 is a predominantly cytoplasmic RNA-binding protein that is essential for nonsense-mediated RNA decay pathway. Coimmunoprecipitation analyses in transfected cells confirmed a specific interaction between nsp1 and Upf1. Small interfering RNA-mediated knockdown of Upf1 resulted in suppression of nsp1-mediated RNA cleavage. Our data indicate a novel mechanism of host mRNA cleavage by SARA-CoV nsp1 protein.