Release factor binding to ribosome requires an intact 16 S rRNA 3' terminus.

Cloacin DF12 cleavage of Escherichia coli f[3H]MettRNA-AUG-ribosome complexes affects this substrate for in vitro peptide chain termination. Codon-directed release factors' (RF) 1 and 2 release of f[3H]methionine is inhibited by cloacin. Since cloacin inhibits RF1 and -2 binding to ribosomes but not RF-directed f[3H]methionine release from f[3H]met-tRNA-AUG-ribosome complexes when reactions contain 20% ethanol, we conclude that cloacin DF 13 inhibits formation of the termination codon recognition complex. Thus, cleavage of the 3'-OH 49-nucleotide sequence of the 16 S rRNA perturbs the codon-directed binding of RF to ribosomes.