Binding of [14C]tuberactinomycin O, an antibiotic closely related to viomycin, to the bacterial ribosome

The binding of [14C]tuberactinomycin O, an antibiotic closely related to viomycin, to E. coli ribosomes has been examined by equilibrium dialysis method. The antibiotic has been observed to bind to the 70S ribosome, which possesses two binding sites: one on the 30S ribosomal subunit and another on the 50S subunit. The affinity for the large subunit is greater than that for the small subunit. The binding to both ribosomal subunits is reversed by viomycin, indicating that tuberactinomycin O and viomycin have the same binding sites on the ribosome. The results seem to be in accordance with the previous finding that viomycin exhibits dual actions on ribosomal function: the inhibition of fMet-tRNAF (initiation) and inhibition of translocation of peptidyl-tRNA.