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Updated: May 21, 2026
Production of Human Norovirus Protruding Domains in E. coli for X-ray Crystallography
Published on: April 19, 2016
Structure of a murine norovirus NS6 protease-product complex revealed by adventitious crystallisation
Eoin N Leen1, Gabriela Baeza, Stephen Curry
1Department of Life Sciences, Imperial College, London, United Kingdom.
Abstract:
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.
Insights
Murine norovirus NS6 protease (MNV NS6pro) crystal structure reveals how it binds its own C-terminal peptide product. This finding offers insights into norovirus protease specificity and pathogenesis.
Area of Science:
- Virology
- Structural Biology
- Biochemistry
Background:
- Murine noroviruses (MNV) are key models for studying human norovirus infection and gastroenteritis.
- Norovirus replication depends on viral protease NS6 (NS6pro) processing a polyprotein into non-structural proteins.
- Understanding MNV NS6pro function is crucial for developing antiviral strategies.
Purpose of the Study:
- To determine the crystal structure of MNV NS6pro.
- To elucidate the structural basis of MNV NS6pro substrate specificity.
- To gain insights into the protease-product complex formation.
Main Methods:
- X-ray crystallography of MNV NS6pro.
- Analysis of crystal contacts revealing protease-peptide interactions.
- Structural comparison to understand enzyme specificity.
Main Results:
- The crystal structure of MNV NS6pro was determined at 1.6 Å resolution.
- Crystal contacts revealed the C-terminus of NS6pro binding within its own active site, mimicking a product complex.
- This binding mode provides a structural view of the protease-product interaction post-cleavage.
Conclusions:
- The crystal structure reveals a physiologically relevant protease-product complex.
- This structure offers new insights into the specificity determinants of MNV NS6pro.
- Findings contribute to understanding norovirus replication and potential therapeutic targets.
