IN VIVO REMOVAL OF PROTEIN FROM TOBACCO MOSAIC VIRUS AFTER INOCULATION OF TOBACCO LEAVES .2. SOME CHARACTERISTICS OF REACTION

Intact virus protein subunits were released from parental TMV from 10 min to 4 hours after inoculation of tobacco leaves. The reaction appeared to occur in two stages. The initial removal of one-quarter of the virus protein, which occurred within 10 min, was unaffected by low temperature or by inhibition of protein synthesis in the leaves by cycloheximide. Thus the initial disruption of the virus immediately after inoculation does not appear to be dependent upon the activities of induced or preexisting enzymes. This lends support to the idea that uncoating of TMV-RNA begins in a hydrophobic environment by a physical disruption of the bonds that bind protein subunits together and to the nucleic acid. The second stage, lasting up to 4-5 hours, during which another 25% of the protein was removed, was inhibited by both low temperature and cycloheximide. The reaction was found to be non-host-specific since at least the earliest stages occurred in plants which are not considered to be hosts of TMV. © 1969.