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. 2004 Feb 25;12(2):341–353. doi: 10.1016/j.str.2004.01.016

The nsp9 Replicase Protein of SARS-Coronavirus, Structure and Functional Insights

Geoff Sutton a, Elizabeth Fry a, Lester Carter a,b, Sarah Sainsbury b, Tom Walter b, Joanne Nettleship b, Nick Berrow b, Ray Owens b, Robert Gilbert a, Andrew Davidson c, Stuart Siddell c, Leo LM Poon d, Jonathan Diprose b, David Alderton b, Martin Walsh e, Jonathan M Grimes a,b, David I Stuart a,b,*
PMCID: PMC7135010  PMID: 14962394

Abstract

As part of a high-throughput structural analysis of SARS-coronavirus (SARS-CoV) proteins, we have solved the structure of the non-structural protein 9 (nsp9). This protein, encoded by ORF1a, has no designated function but is most likely involved with viral RNA synthesis. The protein comprises a single β-barrel with a fold previously unseen in single domain proteins. The fold superficially resembles an OB-fold with a C-terminal extension and is related to both of the two subdomains of the SARS-CoV 3C-like protease (which belongs to the serine protease superfamily). nsp9 has, presumably, evolved from a protease. The crystal structure suggests that the protein is dimeric. This is confirmed by analytical ultracentrifugation and dynamic light scattering. We show that nsp9 binds RNA and interacts with nsp8, activities that may be essential for its function(s).

Published online: January 16, 2004

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