Over recent years, we have been living under a pandemic, caused by the rapid spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). One of the major virulence factors of Coronaviruses is the Non-structural protein 1 (Nsp1), known to suppress the host cells protein translation machinery, allowing the virus to produce its own proteins, propagate and invade new cells. To unveil the molecular mechanisms of SARS-CoV2 Nsp1, we have addressed its biochemical and biophysical properties in the presence of calcium, magnesium and manganese. Our findings indicate that the protein in solution is a monomer and binds to both manganese and calcium, with high affinity. Surprisingly, our results show that SARS-CoV2 Nsp1 alone displays metal-dependent endonucleolytic activity towards both RNA and DNA, regardless of the presence of host ribosome. These results show Nsp1 as new nuclease within the coronavirus family. Furthermore, the Nsp1 double variant R124A/K125A presents no nuclease activity for RNA, although it retains activity for DNA, suggesting distinct binding sites for DNA and RNA. Thus, we present for the first time, evidence that the activities of Nsp1 are modulated by the presence of different metals, which are proposed to play an important role during viral infection. This research contributes significantly to our understanding of the mechanisms of action of Coronaviruses.

近年来，我们一直生活在由严重急性呼吸综合征冠状病毒 2 (SARS-CoV2) 迅速传播引起的大流行之下。冠状病毒的主要毒力因子之一是非结构蛋白 1 (Nsp1)，已知它可以抑制宿主细胞蛋白质翻译机制，使病毒能够产生自己的蛋白质、繁殖和侵入新细胞。为了揭示 SARS-CoV2 Nsp1 的分子机制，我们研究了其在钙、镁和锰存在下的生化和生物物理特性。我们的研究结果表明，溶液中的蛋白质是单体，并且以高亲和力与锰和钙结合。令人惊讶的是，我们的结果表明，无论宿主核糖体是否存在，单独的 SARS-CoV2 Nsp1 对 RNA 和 DNA 都表现出金属依赖性核酸内切活性。这些结果表明 Nsp1 是冠状病毒家族中的新核酸酶。此外，Nsp1 双变体 R124A/K125A 对 RNA 不具有核酸酶活性，尽管它保留对 DNA 的活性，这表明 DNA 和 RNA 具有不同的结合位点。因此，我们首次提出证据表明 Nsp1 的活性受到不同金属的存在调节，这些金属被认为在病毒感染过程中发挥着重要作用。这项研究对我们了解冠状病毒的作用机制做出了重大贡献。