title: Structure, stability and dynamics of norovirus P domain derived protein complexes studied by native mass spectrometry.
abstract: Expression of the protruding (P) domain of the norovirus capsid protein, in vitro, results in the formation of P dimers and larger oligomers, 12-mer and 24-mer P particles. All these P complexes retain the authentic antigenicity and carbohydrate-binding function of the norovirus capsid. They have been used as tools to study norovirus-host interactions, and the 24-mer P particle has been proposed as a vaccine and vaccine platform against norovirus and other pathogens. In view of their pharmaceutical interest it is important to characterise the structure, stability and dynamics of these protein complexes. Here we use a native mass spectrometric approach. We analyse the P particles under both non-reducing and reducing conditions, as it is known that the macromolecular assemblies are stabilised by inter-subunit disulphide bonding. A novel 18-mer complex is identified, and we show that under reducing conditions the 24-mer dissociates into P dimers that reassemble into the 12-mer small P particle and another novel 36-mer complex. The collisional cross-sections of the 12-mer and 24-mer P particles determined by ion mobility MS are in good agreement with theoretical predictions and electron microscopy data. We propose a model structure for the 18-mer based on ion mobility experiments. Our results demonstrate the interchangeable nature and dynamic relationship of all P domain complexes and confirm their binding activity to the host receptors - human histo blood group antigens (HBGAs). These findings, together with the identification of the 18-mer and 36-mer P complexes add new information to the intriguing interactions of the norovirus P domain.
authors.affiliation: Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: Jessica Z
authors.initials: JZ
authors.lastname: Bereszczak
authors.forename: Ioana M
authors.initials: IM
authors.lastname: Barbu
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: Esther
authors.initials: E
authors.lastname: van Duijn
authors.forename: Albert J R
authors.initials: AJ
authors.lastname: Heck
mesh_terms: D001789:Blood Group Antigens / Q000737:chemistry; D036022:Capsid Proteins / Q000737:chemistry*; D004229:Dithiothreitol / Q000737:chemistry; D054884:Host-Pathogen Interactions; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D046912:Multiprotein Complexes / Q000737:chemistry; D029322:Norovirus / Q000502:physiology*; D011485:Protein Binding; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D019163:Reducing Agents / Q000737:chemistry; D012463:Saliva / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D001789:Blood Group Antigens; D036022:Capsid Proteins; D046912:Multiprotein Complexes; D019163:Reducing Agents; D004229:Dithiothreitol