title: C-terminal arginine cluster is essential for receptor binding of norovirus capsid protein.
abstract: Noroviruses are the major viral pathogens of epidemic acute gastroenteritis affecting people worldwide. They have been found to recognize human histo-blood group antigens as receptors. The P domain of norovirus capsid protein was found to be responsible for binding to viral receptors, and the recombinant P protein forms P dimers and P particles in vitro. In this study, we demonstrate that a highly conserved arginine (R) cluster at the C terminus of the P domain is critical for receptor binding and P particle formation of the P proteins. Deletions of the R cluster abolished these functions. Replacement of the R cluster with histidines (another positively charged amino acid) resulted in low efficiency of receptor binding and P particle formation, while replacement with alanines led to loss of both functions completely. The R cluster also contains a highly conserved trypsin digestion site. A treatment of capsid protein or P domain mutants from both genogroup I (Norwalk virus) and genogroup II (VA387) noroviruses with trypsin resulted in a removal of the R cluster and the S domain, leaving a P polypeptide of 31.3 kDa (Norwalk virus) or 34.3 kDa (VA387), similar to the soluble P protein found in vivo. Our findings imply that the proteolytic process could be a necessary step for norovirus replication in the host.
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: Jarek
authors.initials: J
authors.lastname: Meller
authors.forename: Xi
authors.initials: X
authors.lastname: Jiang
mesh_terms: D000818:Animals; D001120:Arginine / Q000235:genetics / Q000378:metabolism*; D036022:Capsid Proteins / Q000378:metabolism*; D019281:Dimerization; D006801:Humans; D009154:Mutation; D029322:Norovirus / Q000502:physiology*; D010446:Peptide Fragments / Q000502:physiology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011991:Receptors, Virus / Q000378:metabolism*; D011994:Recombinant Proteins; D012463:Saliva / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D018411:Spodoptera; D014771:Virion / Q000302:isolation & purification
chemical_list: D036022:Capsid Proteins; D010446:Peptide Fragments; D011991:Receptors, Virus; D011994:Recombinant Proteins; D001120:Arginine