Alcohol-Perturbed Self-Assembly of Tobacco Mosaic Virus Coat Protein

Self-assembly of Tobacco mosaic virus coat protein is significantly altered in alcohol-water mixtures. Alcohol cosolvents stabilize the disk aggregate and prevent formation of helical rods at low pH. High alcohol content favours stacked disk assemblies and large rafts, while low alcohol concentration favours individual disks and short stacks. These effects appear to be caused by the hydrophobicity of the alcohol additive, with isopropyl alcohol having the strongest effect, and methanol the weakest. We hypothesize that alcohols interact with the hydrophobic faces of TMV-cp disks, thereby disrupting the protein-protein interactions between disks that are necessary to form helical rods.