title: The P domain of norovirus capsid protein forms dimer and binds to histo-blood group antigen receptors.
abstract: Noroviruses (NVs) are the most important pathogen of epidemic nonbacterial gastroenteritis. The recent finding that NVs recognize human histo-blood group antigens (HBGAs) as receptors provided a new approach to study the pathogenesis of NVs. Using computational and site-directed mutagenesis approaches, our investigators previously identified a plausible binding pocket in the P domain of the NV capsids. In this study, we further characterize the role of the P domain in the interaction with human HBGA receptors using three NV strains representing three binding patterns. Our results show that the isolated P domain, although it did not form virus-like particles (VLPs), formed dimers, and the dimers bound HBGAs with the same patterns as those of the intact viral capsids. In contrast, the S domain, which formed small, thin-layer VLPs, did not bind A, B, or H HBGAs. A chimera containing the S domain of VA387 and the P domain of MOH revealed a binding pattern of the P donor strain (MOH). Deletion experiments revealed that an intact P domain is necessary for receptor binding. The P domain dimers are stable over a broad range of pH (2 to 11) or under strong denaturing conditions. Taken together, our results suggest that the P domain of NV contains essential elements for strain-specific binding to receptors. Further study of the P domain will provide useful information about the virus-receptor interaction. The high yield and easy production of the recombinant P protein in the Escherichia coli expression system will provide a simple approach to this goal.
authors.affiliation: Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Tan
authors.forename: Rashmi S
authors.initials: RS
authors.lastname: Hegde
authors.forename: Xi
authors.initials: X
authors.lastname: Jiang
mesh_terms: D000017:ABO Blood-Group System; D001789:Blood Group Antigens / Q000378:metabolism*; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D029322:Norovirus / Q000378:metabolism / Q000472:pathogenicity*; D011991:Receptors, Virus / Q000378:metabolism*
chemical_list: D000017:ABO Blood-Group System; D001789:Blood Group Antigens; D036022:Capsid Proteins; C121877:Norwalk virus capsid; D011991:Receptors, Virus