title: The nucleocapsid protein of coronavirus infectious bronchitis virus: crystal structure of its N-terminal domain and multimerization properties.
abstract: The coronavirus nucleocapsid (N) protein packages viral genomic RNA into a ribonucleoprotein complex. Interactions between N proteins and RNA are thus crucial for the assembly of infectious virus particles. The 45 kDa recombinant nucleocapsid N protein of coronavirus infectious bronchitis virus (IBV) is highly sensitive to proteolysis. We obtained a stable fragment of 14.7 kDa spanning its N-terminal residues 29-160 (IBV-N29-160). Like the N-terminal RNA binding domain (SARS-N45-181) of the severe acute respiratory syndrome virus (SARS-CoV) N protein, the crystal structure of the IBV-N29-160 fragment at 1.85 A resolution reveals a protein core composed of a five-stranded antiparallel beta sheet with a positively charged beta hairpin extension and a hydrophobic platform that are probably involved in RNA binding. Crosslinking studies demonstrate the formation of dimers, tetramers, and higher multimers of IBV-N. A model for coronavirus shell formation is proposed in which dimerization of the C-terminal domain of IBV-N leads to oligomerization of the IBV-nucleocapsid protein and viral RNA condensation.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551.
authors.forename: Hui
authors.initials: H
authors.lastname: Fan
authors.forename: Amy
authors.initials: A
authors.lastname: Ooi
authors.forename: Yong Wah
authors.initials: YW
authors.lastname: Tan
authors.forename: Sifang
authors.initials: S
authors.lastname: Wang
authors.forename: Shouguo
authors.initials: S
authors.lastname: Fang
authors.forename: Ding Xiang
authors.initials: DX
authors.lastname: Liu
authors.forename: Julien
authors.initials: J
authors.lastname: Lescar
mesh_terms: D000595:Amino Acid Sequence; D000086462:Coronavirus Nucleocapsid Proteins; D003461:Crystallography; D019281:Dimerization; D001351:Infectious bronchitis virus; D008969:Molecular Sequence Data; D019251:Nucleocapsid / Q000737:chemistry; D019590:Nucleocapsid Proteins / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism
chemical_list: D000086462:Coronavirus Nucleocapsid Proteins; D019590:Nucleocapsid Proteins; D012313:RNA