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Analysis of Translation Initiation During Stress Conditions by Polysome Profiling
Published on: May 19, 2014
Hypusine-containing protein eIF5A promotes translation elongation
Preeti Saini1, Daniel E Eyler, Rachel Green
1Laboratory of Gene Regulation and Development, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA.
Nature
|May 9, 2009
Summary
The translation factor eIF5A, containing the unique amino acid hypusine, is crucial for protein synthesis. This study demonstrates eIF5A promotes translation elongation, not initiation, by aiding ribosomal translocation alongside eEF2.
Area of Science:
- Molecular Biology
- Protein Synthesis
- Genetics
Background:
- Translation elongation factors like EF-Tu and EF-G are essential for protein synthesis.
- eIF5A, a unique eukaryotic factor containing hypusine, was previously thought to aid translation initiation.
- The exact function of eIF5A in cellular processes remained unclear, with links to mRNA decay and transport.
Purpose of the Study:
- To elucidate the precise cellular role of the translation factor eIF5A.
- To investigate whether eIF5A functions in translation initiation or elongation.
- To determine the mechanism by which eIF5A influences protein synthesis.
Main Methods:
- Molecular genetic studies in Saccharomyces cerevisiae.
- Biochemical assays, including in vitro synthesis.
- Analysis of polysome accumulation and ribosomal transit times.
- Inactivation and depletion of eIF5A.
- Testing recombinant eIF5A activity.
Main Results:
- Depletion or inactivation of eIF5A led to polysome accumulation and increased ribosomal transit times in yeast.
- Recombinant eIF5A, but not a hypuseless derivative, enhanced in vitro tripeptide synthesis.
- eIF5A inactivation mimicked the effects of the eEF2 inhibitor sordarin.
- eIF5A is structurally homologous to bacterial EF-P.
Conclusions:
- eIF5A is a translation elongation factor, not primarily involved in initiation.
- eIF5A promotes ribosomal translocation, potentially cooperating with eEF2.
- The eIF5A/EF-P family represents a universally conserved translation elongation factor.
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