Distinct response of yeast ribosomes to a miscoding event during translation.

Numerous mechanisms have evolved to control the accuracy of translation, including a recently discovered retrospective quality control mechanism in bacteria. This quality control mechanism is sensitive to perturbations in the codon:anticodon interaction in the P site of the ribosome that trigger a dramatic loss of fidelity in subsequent tRNA and release factor selection events in the A site. These events ultimately lead to premature termination of translation in response to an initial miscoding error. In this work, we extend our investigations of this mechanism to an in vitro reconstituted Saccharomyces cerevisiae translation system. We report that yeast ribosomes do not respond to mismatches in the P site by loss of fidelity in subsequent substrate recognition events. We conclude that retrospective editing, as initially characterized in Escherichia coli, does not occur in S. cerevisiae. These results highlight potential mechanistic differences in the functional core of highly conserved ribosomes.