Intermolecular Interactions of Chrysanthemum virus B Coat Protein: Implications for Capsid Assembly.

Chrysanthemum virus B coat protein constitutes the viral capsid which, besides other functions, encapsulates and protects the viral nucleic acid. We have demonstrated homotypic interaction of the coat protein subunits, essentially important for dimer formation, which is the first step during capsid assembly in vivo and in vitro. Interaction capacity of full length and truncated protein has been investigated and important regions have been identified through protein-protein interaction in yeast and by co-immunoprecipitation assays. Complete coat protein was found to interact strongly with similar subunits. Constructs with 102 amino acids from the N-terminal and 64 amino acids from C-terminal were found to be inconsequential for dimer formation as they did not show any interaction with similar subunits or with full length protein when analysed for β-galactosidase or histidine prototrophy. Results suggest that the region of 98-184 amino acids from the middle plays an important role in the process, probably without the involvement of N- and C- terminals.