Abstract
Interaction between E and prM proteins in flavivirus-infected cells is a major factor for virus-like particle (VLP) production. The prM helical (prM-H) domain is topologically close to and may interact with domain II of the E protein (EDII) following rearrangement triggered by low pH. In this study, the involvement of the prM-H domain of the Japanese encephalitis virus in VLP production and interaction with EDII was investigated. The prM-H domain was characterized using amino acid substitution mutations to disrupt interaction between prM-H and EDII; we then analyzed the effects of these substitutions on VLP production. The results indicate that substitutions of negatively charged prM-E125 residues with non-charged and positively charged residues significantly impaired both VLP production and the binding of prM-H oligopeptides to EDI/II proteins. Further, after making alanine substitutions of positively charged E-K93 and E-H246 residues (known to interact with the prM-H domain) at EDII resulted in decreased VLP production. Exchanges of oppositely charged residue side chains at prM-E125K/E-K93E and prM-E125H/E-H246E did not impair prM-H oligopeptide binding to EDI/II proteins, but did result in partial VLP production recovery. The prM-E125 and E-H246 residues are conserved and that the positive charge of the E-K93 residue is preserved in different flavivirus groups. These findings suggest that the electrostatic attractions of prM-E125, E-K93 and E-H246 residues are vital to flavivirus VLP production and inhibiting these interactions is a potential strategy for blocking flavivirus infections.