Intramolecular disulfide bonding is essential for betanodavirus coat protein conformation

Here we report on the conformational changes that are responsible for the appearance of the Dicentrarchus labrax encephalitis virus (DlEV) coat protein as a doublet in SDS-PAGE. Wild-type and mutated forms of the coat protein cDNA were expressed in E. coli. The study of the resulting recombinant molecules excluded the possibility of the involvement of a precursor autocatalysis mechanism or a ribosomal frameshifting event in the doublet formation. The appearance of the coat protein doublet was found to be beta-mercaptoethanol sensitive. Based on this observation, we carried out substitution of all cysteine residues. The obtained results demonstrated the importance of intramolecular disulfide bonding between cysteines 187 and 201 on coat protein conformational changes.