title: Transient oligomerization of the SARS-CoV N protein--implication for virus ribonucleoprotein packaging.
abstract: The nucleocapsid (N) phosphoprotein of the severe acute respiratory syndrome coronavirus (SARS-CoV) packages the viral genome into a helical ribonucleocapsid and plays a fundamental role during viral self-assembly. The N protein consists of two structural domains interspersed between intrinsically disordered regions and dimerizes through the C-terminal structural domain (CTD). A key activity of the protein is the ability to oligomerize during capsid formation by utilizing the dimer as a building block, but the structural and mechanistic bases of this activity are not well understood. By disulfide trapping technique we measured the amount of transient oligomers of N protein mutants with strategically located cysteine residues and showed that CTD acts as a primary transient oligomerization domain in solution. The data is consistent with the helical oligomer packing model of N protein observed in crystal. A systematic study of the oligomerization behavior revealed that altering the intermolecular electrostatic repulsion through changes in solution salt concentration or phosphorylation-mimicking mutations affects oligomerization propensity. We propose a biophysical mechanism where electrostatic repulsion acts as a switch to regulate N protein oligomerization.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, Republic of China.
authors.forename: Chung-ke
authors.initials: CK
authors.lastname: Chang
authors.forename: Chia-Min Michael
authors.initials: CM
authors.lastname: Chen
authors.forename: Ming-hui
authors.initials: MH
authors.lastname: Chiang
authors.forename: Yen-lan
authors.initials: YL
authors.lastname: Hsu
authors.forename: Tai-huang
authors.initials: TH
authors.lastname: Huang
mesh_terms: D019943:Amino Acid Substitution; D002119:Calcium Carbonate; D002951:Citrates; D003553:Cystine / Q000737:chemistry; D004338:Drug Combinations; D008277:Magnesium Oxide; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D019590:Nucleocapsid Proteins / Q000737:chemistry* / Q000235:genetics; D010766:Phosphorylation; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D011499:Protein Processing, Post-Translational; D045473:Severe acute respiratory syndrome-related coronavirus; D019065:Virus Assembly
chemical_list: D002951:Citrates; D004338:Drug Combinations; D019590:Nucleocapsid Proteins; C050615:Suby's G solution; D008277:Magnesium Oxide; D003553:Cystine; D002119:Calcium Carbonate