Hydrolysis of fMet-tRNA by Peptidyl Transferase

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Abstract
Escherichia coli and rabbit reticulocyte (f[3H]Met-tRNA·AUG·ribosome) intermediates undergo hydrolysis, with release of f[3H]methionine, upon addition of tRNA or CpCpA in the presence of acetone. This ribosomal catalyzed reaction has similar requirements, pH optimum, and antibiotic sensitivity to those of peptidyl transferase. Two antibiotics, lincomycin with E. coli ribosomes and anisomycin with reticulocyte ribosomes, inhibit peptide-bond formation and transesterification activities of peptidyl transferase, but stimulate hydrolysis of f[3H]Met-tRNA. Earlier studies have suggested peptidyl transferase activity is essential for R factor-dependent hydrolysis of f(3H)Met-tRNA. These studies indicate that peptidyl transferase has the capacity for f(3H)Met-tRNA hydrolysis and, therefore, may be responsible for peptidyl-tRNA cleavage during peptide chain termination.