Structural characterization of Nonstructural protein 1 from SARS-CoV-2

Abstract

Severe acute respiratory syndrome (SARS) coronavirus-2 (SARS-CoV-2) is a single-stranded, enveloped RNA virus and the etiological agent of the current COVID-19 pandemic. Efficient replication of the virus relies on the activity of nonstructural protein 1 (Nsp1), a major virulence factor shown to facilitate suppression of host gene expression through promotion of host mRNA degradation and interaction with the 40S ribosomal subunit. Here, we report the crystal structure of the globular domain of SARS-CoV-2 Nsp1, encompassing residues 13 to 127, at a resolution of 1.65 [A]. Our structure features a six-stranded, capped {beta}-barrel motif similar to Nsp1from SARS-CoV and reveals how variations in amino acid sequence manifest as distinct structural features. Through comparative analysis of structural homologues, we identified a topological signature associated with this protein fold that facilitated modeling of Nsp1 from MERS-CoV. Combining our high-resolution crystal structure with existing data on the C-terminus of Nsp1 from SARS-CoV-2, we propose a model of the full-length protein. Our results provide unparalleled insight into the molecular structure of a major pathogenic determinant of SARS-CoV-2.