PDF(Pubmed)
Abstract：
Nsp1 of SARS-CoV-2 regulates the translation of host and viral mRNAs in cells. Nsp1 inhibits host translation initiation by occluding the entry channel of the 40S ribosome subunit. The structural study of the Nsp1-ribosomal complexes reported post-termination 80S complex containing Nsp1, eRF1 and ABCE1. Considering the presence of Nsp1 in the post-termination 80S ribosomal complex, we hypothesized that Nsp1 may be involved in translation termination. Using a cell-free translation system and reconstituted in vitro translation system, we show that Nsp1 stimulates peptide release and formation of termination complexes. Detailed analysis of Nsp1 activity during translation termination stages reveals that Nsp1 facilitates stop codon recognition. We demonstrate that Nsp1 stimulation targets eRF1 and does not affect eRF3. Moreover, Nsp1 increases amount of the termination complexes at all three stop codons. The activity of Nsp1 in translation termination is provided by its N-terminal domain and the minimal required part of eRF1 is NM domain. We assume that the biological meaning of Nsp1 activity in translation termination is binding with the 80S ribosomes translating host mRNAs and remove them from the pool of the active ribosomes.
摘要：
SARS-CoV-2的Nsp1调节细胞中宿主和病毒mRNA的翻译。Nsp1通过封闭40S核糖体亚基的入口通道来抑制宿主翻译起始。Nsp1-核糖体复合物的结构研究报告了包含Nsp1，eRF1和ABCE1的终止后80S复合物。考虑到Nsp1在终止后80S核糖体复合物中的存在，我们假设Nsp1可能参与翻译终止。使用无细胞翻译系统和重建的体外翻译系统，我们显示Nsp1刺激肽释放和终止复合物的形成。在翻译终止阶段对Nsp1活性的详细分析揭示了Nsp1促进终止密码子识别。我们证明Nsp1刺激靶向eRF1而不影响eRF3。此外，Nsp1增加了所有三个终止密码子处的终止复合物的量。Nsp1在翻译终止中的活性由其N-末端结构域提供,并且eRF1的最小所需部分是NM结构域。我们假设翻译终止中Nsp1活性的生物学意义是与80S核糖体结合，并将其从活性核糖体池中除去。
