title: Structural basis for the receptor binding specificity of Norwalk virus.
abstract: Noroviruses are positive-sense, single-stranded RNA viruses that cause acute gastroenteritis. They recognize human histo-blood group antigens as receptors in a strain-specific manner. The structures presented here were analyzed in order to elucidate the structural basis for differences in ligand recognition of noroviruses from different genogroups, the prototypic Norwalk virus (NV; GI-1) and VA387 (GII-4), which recognize the same A antigen but differ in that NV is unable to bind to the B antigen. Two forms of the receptor-binding domain of the norovirus coat protein, the P domain and the P polypeptide, that were previously shown to differ in receptor binding and P-particle formation properties were studied. Comparison of the structures of the NV P domain with and without A trisaccharide and the NV P polypeptide revealed no major ligand-induced changes. The 2.3-A cocrystal structure reveals that the A trisaccharide binds to the NV P domain through interactions with the residues Ser377, Asp327, His329, and Ser380 in a mode distinct from that previously reported for the VA387 P-domain-A-trisaccharide complex. Mutational analyses confirm the importance of these residues in NV P-particle binding to native A antigen. The alpha-GalNAc residue unique to the A trisaccharide is buried deeply in the NV binding pocket, unlike in the structures of A and B trisaccharides bound to VA387 P domain, where the alpha-fucose residue forms the most protein contacts. The A-trisaccharide binding mode seen in the NV P domain complex cannot be sterically accommodated in the VA387 P domain.
authors.affiliation: Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
authors.forename: Weiming
authors.initials: W
authors.lastname: Bu
authors.forename: Aygun
authors.initials: A
authors.lastname: Mamedova
authors.forename: Ming
authors.initials: M
authors.lastname: Tan
authors.forename: Ming
authors.initials: M
authors.lastname: Xia
authors.forename: Xi
authors.initials: X
authors.lastname: Jiang
authors.forename: Rashmi S
authors.initials: RS
authors.lastname: Hegde
mesh_terms: D000595:Amino Acid Sequence; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009663:Norwalk virus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011991:Receptors, Virus / Q000737:chemistry* / Q000378:metabolism*; D012680:Sensitivity and Specificity; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D009844:Oligosaccharides; D010455:Peptides; D011991:Receptors, Virus; D014764:Viral Proteins