Hot-spots and their contribution to the self-assembly of the viral capsid: in-vitro validation

The viral capsid is a macromolecular complex formed by self-assembled proteins which, in many cases, are biopolymers with an identical amino acid sequence. Specific protein-protein interactions drive the capsid self-assembly process. However, it is believed that only a small set of interface residues significantly contribute to the formation of the capsid, the so-called "hot-spots". Here, we investigate the effect of point-mutations on previously predicted hot-spots of the icosahedral Cowpea Chlorotic Mottle Virus. We characterize the formation and stability of virus-like particles in-vitro by thermal shift assays. Our results show that a single mutation on residue E176 or V189 significantly perturbs the quaternary protein-protein interaction, preventing the formation of the capsid. Furthermore, these mutations do not destroy the tertiary fold of the capsid protein. Our findings give evidence of the in-silico hot-spot prediction accuracy. As a whole, our methodology provides a guide to the rational development of molecules that could inhibit virus formation.