Eukaryotic translation initiation factor 3 plays distinct roles at the mRNA entry and exit channels of the ribosomal preinitiation complex
- National Institutes of Health, United States
- Institute of Microbiology ASCR, Czech Republic
- PharmaEssentia Corporation, Taiwan
Abstract
Eukaryotic translation initiation factor 3 (eIF3) is a central player in recruitment of the pre-initiation complex (PIC) to mRNA. We probed the effects on mRNA recruitment of a library of S. cerevisiae eIF3 functional variants spanning its 5 essential subunits using an in vitro-reconstituted system. Mutations throughout eIF3 disrupt its interaction with the PIC and diminish its ability to accelerate recruitment to a native yeast mRNA. Alterations to the eIF3a CTD and eIF3b/i/g significantly slow mRNA recruitment, and mutations within eIF3b/i/g destabilize eIF2•GTP•Met-tRNAi binding to the PIC. Using model mRNAs lacking contacts with the 40S entry or exit channels, we uncover a critical role for eIF3 requiring the eIF3a NTD, in stabilizing mRNA interactions at the exit channel, and an ancillary role at the entry channel requiring residues of the eIF3a CTD. These functions are redundant: defects at each channel can be rescued by filling the other channel with mRNA.
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Author details
Funding
National Institutes of Health (Intramural Research Program)
- Colin Echeverría Aitken
- Wen-Ling Chiu
- Fujun Zhou
- Alan G Hinnebusch
- Jon R Lorsch
Wellcome (090812/B/09/Z)
- Colin Echeverría Aitken
- Leoš Shivaya Valášek
Centrum of Excellence of the Czech Science Foundation (P305/12/G034)
- Colin Echeverría Aitken
- Leoš Shivaya Valášek
Leukemia and Lymphoma Society (5199-12)
- Colin Echeverría Aitken
National Institutes of Health (GM62128)
- Jon R Lorsch
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
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Eukaryotic translation initiation factor 3 plays distinct roles at the mRNA entry and exit channels of the ribosomal preinitiation complex
eLife 5:e20934.
https://doi.org/10.7554/eLife.20934
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