Frameshifting at collided ribosomes is modulated by elongation factor eEF3 and by integrated stress response regulators Gcn1 and Gcn20
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
- Corresponding author: elizabeth_grayhack{at}urmc.rochester.edu
Abstract
Ribosome stalls can result in ribosome collisions that elicit quality control responses, one function of which is to prevent ribosome frameshifting, an activity that entails the interaction of the conserved yeast protein Mbf1 with uS3 on colliding ribosomes. However, the full spectrum of factors that mediate frameshifting during ribosome collisions is unknown. To delineate such factors in the yeast Saccharomyces cerevisiae, we used genetic selections for mutants that affect frameshifting from a known ribosome stall site, CGA codon repeats. We show that the general translation elongation factor eEF3 and the integrated stress response (ISR) pathway components Gcn1 and Gcn20 modulate frameshifting in opposing manners. We found a mutant form of eEF3 that specifically suppressed frameshifting, but not translation inhibition by CGA codons. Thus, we infer that frameshifting at collided ribosomes requires eEF3, which facilitates tRNA–mRNA translocation and E-site tRNA release in yeast and other single cell organisms. In contrast, we found that removal of either Gcn1 or Gcn20, which bind collided ribosomes with Mbf1, increased frameshifting. Thus, we conclude that frameshifting is suppressed by Gcn1 and Gcn20, although these effects are not mediated primarily through activation of the ISR. Furthermore, we examined the relationship between eEF3-mediated frameshifting and other quality control mechanisms, finding that Mbf1 requires either Hel2 or Gcn1 to suppress frameshifting with wild-type eEF3. Thus, these results provide evidence of a direct link between translation elongation and frameshifting at collided ribosomes, as well as evidence that frameshifting is constrained by quality control mechanisms that act on collided ribosomes.
Keywords
- translation
- frameshifting
- ribosome quality control
- eEF3
- integrated stress response
- general amino acid control
Footnotes
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Abbreviations: RQC, ribosome quality control; ISR, integrated stress response; NGD, no-go decay; wt, wild-type; GAAC, general amino acid control
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Article is online at http://www.rnajournal.org/cgi/doi/10.1261/rna.078964.121.
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Freely available online through the RNA Open Access option.
- Received August 26, 2021.
- Accepted November 25, 2021.
This article, published in RNA, is available under a Creative Commons License (Attribution 4.0 International), as described at http://creativecommons.org/licenses/by/4.0/.
