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A eukaryotic translation initiation factor 4E-binding protein promotes mRNA decapping and is required for PUF
Nathan H Blewett1, Aaron C Goldstrohm
1Cellular and Molecular Biology Training Program, University of Michigan Medical School, Ann Arbor, Michigan, USA.
Molecular and Cellular Biology
|August 15, 2012
Summary
Saccharomyces cerevisiae Puf5p uses Eap1p to degrade specific mRNAs by promoting decapping, not translation inhibition. This reveals a new mRNA decay mechanism for eukaryotic RNA-binding proteins.
Area of Science:
- Molecular Biology
- Gene Regulation
- RNA Metabolism
Background:
- PUF proteins are eukaryotic RNA-binding proteins that regulate gene expression by repressing specific messenger RNAs (mRNAs).
- The precise mechanisms and corepressors utilized by PUF proteins for mRNA repression are not fully understood.
- Eukaryotic translation initiation factor 4E (eIF4E)-binding proteins (4E-BPs) are known translational inhibitors.
Purpose of the Study:
- To investigate the repression mechanisms of Saccharomyces cerevisiae Puf5p and Puf4p.
- To identify corepressors involved in Puf5p-mediated mRNA repression.
- To elucidate the role of Eap1p, a 4E-BP, in Puf5p-mediated gene silencing.
Main Methods:
- Investigated Puf5p and Puf4p repression mechanisms in Saccharomyces cerevisiae.
- Assessed the requirement of Eap1p for Puf5p-mediated mRNA repression.
- Analyzed the effect of Eap1p on polyribosome association of target mRNAs.
- Studied mRNA degradation kinetics, specifically decapping and deadenylation.
- Examined protein-protein interactions between Eap1p, Puf5p, and Dhh1p.
Main Results:
- Puf5p requires Eap1p for mRNA repression, while Puf4p does not.
- Eap1p promotes mRNA degradation by accelerating decapping, rather than inhibiting translation initiation.
- Eap1p's interaction with eIF4E is crucial for its decapping-promoting activity.
- Deletion of EAP1 significantly reduces mRNA decapping, leading to mRNA accumulation.
- Eap1p interacts with both Puf5p and the decapping factor Dhh1p.
- Puf5p mediates the recruitment of Eap1p to target mRNAs.
Conclusions:
- Puf5p represses mRNAs by recruiting Eap1p and associated decapping factors, thereby promoting mRNA degradation.
- This study reveals a novel mechanism where a 4E-BP promotes specific mRNA decay pathways.
- Eap1p functions in mRNA degradation by facilitating decapping, expanding the known roles of 4E-BPs beyond translational inhibition.
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