Open AccessTransient Oligomerization of the SARS-CoV N Protein – Implication for Virus Ribonucleoprotein Packaging
Author(s) -
Chung-ke Chang,
Chia Min Michael Chen,
Ming Hui Chiang,
Yen Lan Hsu,
Tai Huang Huang
Publication year - 2013
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0065045
Subject(s) - capsid , biophysics , ribonucleoprotein , oligomer , phosphoprotein , chemistry , dimer , protein structure , intrinsically disordered proteins , viral matrix protein , viral protein , phosphorylation , microbiology and biotechnology , virus , biology , biochemistry , rna , virology , organic chemistry , gene
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.