Infectivity and reconstitution of TMV RNA modified with N-acetoxy-2-acetylaminofluorene or benzol [a] pyrene...

TMV RNA was modified by two bulky carcinogens, N-acetoxy-2-acetylamino-fluorene (AAAF) and (+/-)-7beta, 8alpha- dihydroxy-9alpha, 10alpha-epoxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene (BPDE), and the effects of such substituents on biological and physical properties was studied. For both types of modification, the loss of infectivity was directly proportional to the number of chemical modifications indicating that all modifications are lethal. Neither AAAF nor BPDE produced measurable mutations. Reconstitution of modified RNA with TMV protein was partially inhibited, but such inhibition occurred to similar extents with either carcinogen and a varying levels of modification. The data suggest that both types of substitution of TMV RNA generally permit the TMV coat protein to aggregate normally around the RNA, but that AAAF and BPDE may induce some conformational change in the initiation region that inhibits the initiation step.