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A time-resolved cryo-EM Study of S. cerevisiae 80S Ribosome Protein Composition in Response to a Change in Carbon Source

Ming Sun, Bingxin Shen, Wen Li, Parimal Samir, Christopher M Browne, Andrew Link and Joachim Frank (2020). PROTEOMICS DOI: 10.1002/pmic.202000125

ABSTRACT
The role of the ribosome in the regulation of gene expression has come into increased focus. It has been proposed that ribosomes are catalytic engines capable of changing their protein composition in response to environmental stimuli. We employed time-resolved cryo-electron microscopy (cryo-EM) techniques to identify quantitative changes in the protein composition and structure of the Saccharomyces cerevisiae 80S ribosomes after shifting the carbon source from glucose to glycerol. Using cryo-EM combined with our computational classification approach, we found that a fraction of the yeast cells’ 80S ribosomes lack ribosomal proteins at the entrance and exit sites for tRNAs, including uL16(RPL10), eS1(RPS1), uS11(RPS14A/B)) and eS26(RPS26A/B). This fraction increased after a change from glucose to glycerol medium. Our quantitative structural analysis supports the hypothesis that ribosomes are dynamic complexes that alter their composition in response to changes in growth or environmental conditions. This article is protected by copyright. All rights reserved.

[see Figure on classification results (fig. 2 in MS) below]