Properties of the coat protein of the tobacco mosaic virus Kazakh isolate K1

A study was made of the coat protein (CP) of thermosensitive semidefective tobacco mosaic virus strain K1 (TMV-K1). In contrast to CP of other TMV str ains, K1 CP showed high nonspecific aggregation and did not form normal two -layered cylindrical aggregates. In none of the conditions tested, K1 CP fo rmed virions with cognate K1 RNA in vitro. The abnormal properties were att ributed to substitution Lys53 --> Glu differentiating the K1 CP from those of other tobamoviruses. It is assumed that the high structural plasticity a llows the tobamovirus virions to incorporate CP subunits even with unfavora ble amino acid changes.