Abstract
Cell attachment and membrane penetration are functions of the rotavirus outer capsid spike protein, VP4. An activating tryptic cleavage of VP4 produces the N-terminal fragment, VP8*, which is the viral hemagglutinin and an important target of neutralizing antibodies. We have determined, by X-ray crystallography, the atomic structure of the VP8* core bound to sialic acid and, by NMR spectroscopy, the structure of the unliganded VP8* core. The domain has the beta-sandwich fold of the galectins, a family of sugar binding proteins. The surface corresponding to the galectin carbohydrate binding site is blocked, and rotavirus VP8* instead binds sialic acid in a shallow groove between its two beta-sheets. There appears to be a small induced fit on binding. The residues that contact sialic acid are conserved in sialic acid-dependent rotavirus strains. Neutralization escape mutations are widely distributed over the VP8* surface and cluster in four epitopes. From the fit of the VP8* core into the virion spikes, we propose that VP4 arose from the insertion of a host carbohydrate binding domain into a viral membrane interaction protein.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Binding Sites
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Capsid / chemistry*
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Capsid / physiology
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Capsid Proteins*
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Carbohydrate Metabolism*
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Consensus Sequence
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Crystallography, X-Ray
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Epitopes / chemistry
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Evolution, Molecular
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Galectins
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Hemagglutinins / chemistry
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Hemagglutinins, Viral / biosynthesis
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Hemagglutinins, Viral / chemistry
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Hydrogen Bonding
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Models, Molecular
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Molecular Sequence Data
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N-Acetylneuraminic Acid / metabolism*
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Nuclear Magnetic Resonance, Biomolecular
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Peptide Fragments / chemistry
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Protein Binding
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Protein Conformation
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Protein Folding
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Protein Structure, Secondary
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Protein Structure, Tertiary
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RNA-Binding Proteins / biosynthesis
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RNA-Binding Proteins / chemistry
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Recombinant Fusion Proteins / chemistry
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Rotavirus / chemistry*
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Rotavirus / physiology
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Structure-Activity Relationship
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Substrate Specificity
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Viral Nonstructural Proteins / biosynthesis
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Viral Nonstructural Proteins / chemistry
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Virion / chemistry
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Virion / ultrastructure
Substances
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Capsid Proteins
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Epitopes
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Galectins
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Hemagglutinins
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Hemagglutinins, Viral
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Peptide Fragments
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RNA-Binding Proteins
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Recombinant Fusion Proteins
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VP4 protein, Rotavirus
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Viral Nonstructural Proteins
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nsp1 protein, Rotavirus
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NS35 protein, rotavirus
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N-Acetylneuraminic Acid