Crystal Structure of the SARS-CoV-2 Non-structural Protein 9, Nsp9

Dene R Littler; Benjamin S Gully; Rhys N Colson; Jamie Rossjohn

doi:10.1016/j.isci.2020.101258

Crystal Structure of the SARS-CoV-2 Non-structural Protein 9, Nsp9

iScience. 2020 Jul 24;23(7):101258. doi: 10.1016/j.isci.2020.101258. Epub 2020 Jun 9.

Authors

Dene R Littler¹, Benjamin S Gully², Rhys N Colson³, Jamie Rossjohn⁴

Affiliations

¹ Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia; Australian Research Council Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, VIC, Australia. Electronic address: dene.littler@monash.edu.
² Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia; Australian Research Council Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, VIC, Australia.
³ Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.
⁴ Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia; Australian Research Council Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, VIC, Australia; Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff, UK. Electronic address: jamie.rossjohn@monash.edu.

Abstract

Many of the SARS-CoV-2 proteins have related counterparts across the Severe Acute Respiratory Syndrome (SARS-CoV) family. One such protein is non-structural protein 9 (Nsp9), which is thought to mediate viral replication, overall virulence, and viral genomic RNA reproduction. We sought to better characterize the SARS-CoV-2 Nsp9 and subsequently solved its X-ray crystal structure, in an apo form and, unexpectedly, in a peptide-bound form with a sequence originating from a rhinoviral 3C protease sequence (LEVL). The SARS-CoV-2 Nsp9 structure revealed the high level of structural conservation within the Nsp9 family. The exogenous peptide binding site is close to the dimer interface and impacted the relative juxtapositioning of the monomers within the homodimer. We have established a protocol for the production of SARS-CoV-2 Nsp9, determined its structure, and identified a peptide-binding site that warrants further study to understanding Nsp9 function.

Keywords: 3D Reconstruction of Protein; Protein Structure Aspects; Structural Biology; Virology.