On translational control by ribosome speed inS. cerevisiae

Abstract

In addition to the widespread and well documented control of protein synthesis rates by translation initiation, recent evidence suggests that translation elongation can also control protein synthesis rates. One of the proposed mechanisms leading to elongation control is the interference of slow ribosome movement around the start codon with efficient translation initiation. Here we estimate the frequency with which this mode of control occurs in baker's yeast growing in rich medium. Genome-wide data reveal that transcripts from around 20% of yeast genes show evidence of queueing ribosomes, which we confirm experimentally to be indicative of translation elongation control. Moreover, this subset of transcripts is sensitive to distinct regulatory signals compared to initiation-controlled mRNAs, and we demonstrate that such distinct regulation occurs during the response to osmotic stress. distinct regulatory signals, and that this leads to distinct response dynamics during the onset of stresses.