title: Terminal modifications of norovirus P domain resulted in a new type of subviral particles, the small P particles.
abstract: The protruding (P) domain of norovirus VP1 is responsible for immune recognition and host receptor interaction. Our previous studies have demonstrated that a modification of the ends of the P domain affects the conformation and/or function of the P protein. An expression of the P domain with or without the hinge, or with an additional cysteine at either ends of the P protein resulted in P dimers and/or P particles. Here we report a new type of subviral particle, the small P particles, through a further modification, either an addition of the flag tag or a change of the arginine cluster, at the C-terminus of the cysteine-containing P domain. Gel filtration and cryo-EM studies showed that the small P particles are tetrahedrons formed by 6 P dimers or 12 P monomers that is half-size of the P particles. Fitting of the crystal structure of the P domain into the cryo-EM density map of the particle indicated similar conformations of the P dimers as those in P particles. The small P particles bind human HBGAs and are antigenically reactive similar to their parental VLPs and P particles. These data suggest that the C-terminus of the P domain is an important factor in the formation of the P particles. Further elucidation of the mechanism of these modifications in the P particle formation would be important in structure biology and morphogenesis of noroviruses. The small P particles may also be a useful alternative in study of norovirus-host interaction and vaccine development for noroviruses.
authors.affiliation: Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229-3039, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Tan
authors.forename: Ping-An
authors.initials: PA
authors.lastname: Fang
authors.forename: Ming
authors.initials: M
authors.lastname: Xia
authors.forename: Teepanis
authors.initials: T
authors.lastname: Chachiyo
authors.forename: Wen
authors.initials: W
authors.lastname: Jiang
authors.forename: Xi
authors.initials: X
authors.lastname: Jiang
mesh_terms: D002850:Chromatography, Gel; D020285:Cryoelectron Microscopy; D054884:Host-Pathogen Interactions; D006801:Humans; D046911:Macromolecular Substances / Q000648:ultrastructure; D008958:Models, Molecular; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029322:Norovirus / Q000235:genetics* / Q000648:ultrastructure; D011485:Protein Binding; D055503:Protein Multimerization; D015678:Viral Structural Proteins / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D014765:Viral Vaccines / Q000276:immunology; D022701:Virosomes / Q000648:ultrastructure; D053585:Virus Attachment
chemical_list: D046911:Macromolecular Substances; D050505:Mutant Proteins; D015678:Viral Structural Proteins; D014765:Viral Vaccines; D022701:Virosomes