Structure of a murine norovirus NS6 protease-product complex revealed by adventitious crystallisation.
Murine noroviruses have emerged as a valuable tool for investigating the molecular basis of infection and pathogenesis of the closely related human noroviruses, which are the major cause of non-bacterial gastroenteritis. The replication of noroviruses relies on the proteolytic processing of a large polyprotein precursor into six non-structural proteins (NS1-2, NS3, NS4, NS5, NS6(pro), NS7(pol)) by the virally-encoded NS6 protease. We report here the crystal structure of MNV NS6(pro), which has been determined to a resolution of 1.6 Å. Adventitiously, the crystal contacts are mediated in part by the binding of the C-terminus of NS6(pro) within the peptide-binding cleft of a neighbouring molecule. This insertion occurs for both molecules in the asymmetric unit of the crystal in a manner that is consistent with physiologically-relevant binding, thereby providing two independent views of a protease-peptide complex. Since the NS6(pro) C-terminus is formed in vivo by NS6(pro) processing, these crystal contacts replicate the protease-product complex that is formed immediately following cleavage of the peptide bond at the NS6-NS7 junction. The observed mode of binding of the C-terminal product peptide yields new insights into the structural basis of NS6(pro) specificity.
Department of Life Sciences, Imperial College, London, United Kingdom.
Eoin N
EN
Leen
Gabriela
G
Baeza
Stephen
S
Curry
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D018360:Crystallography, X-Ray; D051379:Mice; D008958:Models, Molecular; D009154:Mutation; D029322:Norovirus / Q000201:enzymology* / Q000235:genetics; D010447:Peptide Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D010455:Peptides; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins; D010447:Peptide Hydrolases