Quaternary Structure of the Severe Acute Respiratory Syndrome (SARS) Coronavirus Main Protease
SARS (severe acute respiratory syndrome) has been one of the most severe viral infectious diseases last year and still remains as a highly risky public health problem around the world. Exploring the types of interactions responsible for structural stabilities of its component protein molecules const...
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Published in | Biochemistry (Easton) Vol. 43; no. 47; pp. 14958 - 14970 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
30.11.2004
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Subjects | |
Online Access | Get full text |
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Summary: | SARS (severe acute respiratory syndrome) has been one of the most severe viral infectious diseases last year and still remains as a highly risky public health problem around the world. Exploring the types of interactions responsible for structural stabilities of its component protein molecules constitutes one of the approaches to find a destabilization method for the virion particle. In this study, we performed a series of experiments to characterize the quaternary structure of the dimeric coronavirus main protease (Mpro, 3CLpro). By using the analytical ultracentrifuge, we demonstrated that the dimeric SARS coronavirus main protease exists as the major form in solution at protein concentration as low as 0.10 mg/mL at neutral pH. The enzyme started to dissociate at acidic and alkali pH values. Ionic strength has profound effect on the dimer stability indicating that the major force involved in the subunit association is ionic interactions. The effect of ionic strength on the protease molecule was reflected by the drastic change of electrostatic potential contour of the enzyme in the presence of NaCl. Analysis of the crystal structures indicated that the interfacial ionic interaction was attributed to the Arg-4···Glu-290 ion pair between the subunits. Detailed examination of the dimer−monomer equilibrium at different pH values reveals apparent pK a values of 8.0 ± 0.2 and 5.0 ± 0.1 for the Arg-4 and Glu-290, respectively. Mutation at these two positions reduces the association affinity between subunits, and the Glu-290 mutants had diminished enzyme activity. This information is useful in searching for substances that can intervene in the subunit association, which is attractive as a target to neutralize the virulence of SARS coronavirus. |
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Bibliography: | istex:2B9EEC83F5D7BDF7B8EA6A12CB2FC2F6D641D3E4 ark:/67375/TPS-LPM5R260-9 This work was supported by the National Science Council, ROC (SARS Project, Grant NSC 92-2751-B-010-004-Y). ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi0490237 |