One more probable structural transition in potato virus X virions and a revised model of the virus coat protein structure

Abstract

We found that a 2-h incubation of potato virus X (PVX) virions in 10 mM Tris–HCl buffer pH 7.5 at − 20 °C results in a strong but reversible drop in virion stability. Under these conditions, the PVX virions are completely disrupted by low (starting from 50 mM) concentrations of LiCl and CaCl 2 but not of NaCl. Incubation of PVX samples with 0.05−2 M LiCl at + 4 °C did not result in virion disassembly and the virions were not disrupted upon incubation at − 20 °C in 10 mM Tris–HCl buffer pH 7.5 without LiCl. We suggest that a 2-h incubation of the PVX virions at − 20 °C in 10 mM Tris–HCl pH 7.5 results in a structural transition in the virus particles. A revised model of the three-dimensional organization of coat protein subunits in the PVX virions is proposed. This two-domain model explains better the high plasticity of the PVX CP structure.