TESTS OF THE RIBOSOMAL EDITING HYPOTHESIS - AMINO-ACID STARVATION DIFFERENTIALLY ENHANCES THE DISSOCIATION OF PEPTIDYL-TRANSFER RNA FROM THE RIBOSOME

Starving Escherichia coli for amino acids affected the dissociation of peptidyl-tRNAs from ribosomes. The frequency of dissociation of specific peptidyl-tRNA families responded differently to starvation for different amino acids rather than uniformly to the general condition of starvation. These results are interpreted in terms of the ribosomal editing hypothesis Menninger 1977. Starvation for some aminoacyl-tRNAs resulted in more opportunities for other aminoacyl-tRNAs to err, providing a greater amount of erroneous peptidyl-tRNA to be dissociated by the ribosomal editor. The details of the response of particular peptidyl-tRNA families to particular amino acid starvations show that a tRNA less able to decode correctly as an aminoacyl-tRNA is more likely to dissociate from the ribosome after peptide transfer. Many of the errors of translation thought previously to be rare may not have been detected in completed proteins because the ribosomal editor is most active against them. The results can also be interpreted as a specific regulatory response to amino acid starvation by a ribosome forced to pause during translation of non-essential proteins at codons whose aminoacyl-tRNAs are limiting, a model known as translational triage. © 1979.