SEVERAL SYMPTOM-MODULATING MUTATIONS IN THE COAT PROTEIN OF TURNIP CRINKLE CARMOVIRUS RESULT IN PARTICLES WITH ABERRANT CONFORMATIONAL PROPERTIES

Particles of several symptom-modulating TCV coat protein (CP) mutants were pretreated at pH 5.5, 7.5 or 8.5 and their conformations compared by agarose gel electrophoresis to those of wild-type particles. Particles of two mutants were swollen under conditions in which wild-type particles remained contracted; particles of one mutant were contracted under conditions in which wildtype particles were swollen; a portion of the particles of one mutant was contracted and another portion swollen under conditions in which wild-type particles remained contracted; and particles of one mutant, that elicited wild-type symptoms, comigrated with wild-type particles under all conditions tested. The results of in vitro translation experiments with mutant particles were essentially similar to those with wild-type particles, despite conformational differences at pH 5.5 and 8.5. These results suggest that more than the swollen conformation is required for in vitro translation, and that particle conformation may play a role in symptom elicitation.