The yeast eukaryotic initiation factor 4B binds the 40S subunit in translation preinitiation complexes (PICs), promoting mRNA recruitment. Recent evidence indicates yeast mRNAs have variable dependence on eIF4B under optimal growth conditions. Given the ability of eIF4B to promote translation as a function of nutrient conditions in mammalian cells, we wondered if eIF4B activities in translation could alter phenotypes in yeast through differential mRNA selection for translation. Here we compared the effects of disrupting yeast eIF4B RNA- and 40S-binding motifs under ∼1400 growth conditions. The RNA-Recognition Motif (RRM) was dispensable for stress responses, but the 40S-binding N-terminal Domain (NTD) promoted growth in response to stressors requiring robust cellular integrity. In particular, the NTD conferred a strong growth advantage in the presence of urea, which may be important for pathogenesis of related fungal species. Ribosome profiling indicated that similar to complete eIF4B deletion, deletion of the NTD dramatically reduced translation, particularly of those mRNAs with long and highly structured 5-prime untranslated regions. This behavior was observed both with and without urea exposure, but the specific mRNA pool associated with ribosomes in response to urea differed. Deletion of the NTD led to relative increases in ribosome association of shorter transcripts with higher dependence on eIF4G, as was noted previously for eIF4B deletion. Gene ontology analysis indicated that proteins encoded by eIF4B NTD-dependent transcripts were associated with the cellular membrane system and the cell wall, while NTD-independent transcripts encoded proteins associated with cytoplasmic proteins and protein synthesis. This analysis highlighted the difference in structure content of mRNAs encoding membrane versus cytoplasmic housekeeping proteins and the variable reliance of specific gene ontology classes on various initiation factors promoting otherwise similar functions. Together our analyses suggest that deletion of the eIF4B NTD prevents cellular stress responses by affecting the capacity to translate a diverse mRNA pool.
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| Evidence ID | Analyze ID | Gene/Complex | Systematic Name/Complex Accession | Qualifier | Gene Ontology Term ID | Gene Ontology Term | Aspect | Annotation Extension | Evidence | Method | Source | Assigned On | Reference |
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| Evidence ID | Analyze ID | Gene | Gene Systematic Name | Phenotype | Experiment Type | Experiment Type Category | Mutant Information | Strain Background | Chemical | Details | Reference |
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| Evidence ID | Analyze ID | Gene | Gene Systematic Name | Disease Ontology Term | Disease Ontology Term ID | Qualifier | Evidence | Method | Source | Assigned On | Reference |
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| Evidence ID | Analyze ID | Regulator | Regulator Systematic Name | Target | Target Systematic Name | Direction | Regulation of | Happens During | Regulator Type | Direction | Regulation Of | Happens During | Method | Evidence | Strain Background | Reference |
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| Site | Modification | Modifier | Source | Reference |
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| Evidence ID | Analyze ID | Interactor | Interactor Systematic Name | Interactor | Interactor Systematic Name | Allele | Assay | Annotation | Action | Phenotype | SGA score | P-value | Source | Reference | Note |
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| Evidence ID | Analyze ID | Interactor | Interactor Systematic Name | Interactor | Interactor Systematic Name | Assay | Annotation | Action | Modification | Source | Reference | Note |
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| Complement ID | Locus ID | Gene | Species | Gene ID | Strain background | Direction | Details | Source | Reference |
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| Dataset | Description | Keywords | Number of Conditions |
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| Binding to the Ribosome by Eukaryotic Initiation Factor 4B Drives Yeast Translational Control in Response to Urea | The yeast eukaryotic initiation factor 4B binds the 40S subunit in translation preinitiation complexes (PICs) and promotes mRNA binding. Here we have compared the effects of disrupting eIF4B RNA- and ribosome-binding domains under ~1400 growth conditions. The RNA-binding RRM was dispensable for stress responses, but ribosome binding stimulated by the NTD promoted growth in response to a number of stressors through changes in translation. In particular, the NTD confers a strong growth advantage in the presence of the denaturing reagent, urea, and a number of osmolytes that require robust cellular integrity for survival. Ribosome profiling of cells with and without the NTD of eIF4B reveals changes in translation of mRNAs containing longer than average and highly structured 5-prime untranslated regions both normally, and in response to urea exposure. Because these changes require 40S binding, our results suggest eIF4B regulates mRNA recruitment as a part of the scanning PIC, rather than by activating isolated mRNPs prior to ribosome binding. This analysis indicates the cellular response to urea in yeast includes a translational component, driven by increased translation of mRNAs encoding proteins associated with the cellular periphery, and highlights the importance of the general translation factor eIF4B in adapting to external conditions. | stress | 16 |
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| Evidence ID | Analyze ID | File | Description |
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