Effects of Anti-microtubule Agents on the Assembly of Tobacco Mosaic Virus Coat Protein

Assembly of the coat protein subunits of tobacco mosaic virus (TMV) into 20S aggregates (‘disks’) and long helices was monitored by light scattering and electron microscopy. The anti-microtubule agent methyl benzimidazol-2-yl carbamate, which inhibits TMV multiplication in vivo, did not affect assembly of coat protein in vitro. In contrast, the anti-microtubule agents colchicine and vinblastine inhibited disk formation, but stimulated rod elongation from coat protein subunits in vitro. Both agents also disrupted preformed disks. Vinblastine inhibited virus multiplication in leaf tissue, but colchicine did not.