Related Experiment Video
Updated: Jun 4, 2026
08:47
Monitoring eIF4F Assembly by Measuring eIF4E-eIF4G Interaction in Live Cells
Published on: May 1, 2020
Elongation factor 4 (EF4/LepA) accelerates protein synthesis at increased Mg2+ concentrations
Markus Pech1, Zhala Karim, Hiroshi Yamamoto
1Max-Planck-Institut für Molekulare Genetik, Abteilung Vingron, AG Ribosomen, Ihnestrasse 73, 14195 Berlin, Germany.
Summary
Elongation factor 4 (EF4) is released under stress, aiding bacterial growth by fixing stuck ribosomes. This explains EF4’s conservation across species.
Area of Science:
- Microbiology
- Molecular Biology
- Protein Synthesis
Background:
- Elongation factor 4 (EF4) is a highly conserved protein found in bacteria and eukaryotic organelles.
- EF4 possesses a unique ability to catalyze ribosome back-translocation.
- The precise physiological function of EF4 remains largely unknown.
Purpose of the Study:
- To elucidate the physiological role of Elongation factor 4 (EF4) in Escherichia coli.
- To investigate the localization and function of EF4 under stress conditions.
Main Methods:
- Localization studies of EF4 in E. coli under varying ionic strength and temperature.
- Growth assays comparing wild-type and EF4-deficient E. coli strains under stress.
- Protein synthesis rate measurements in response to EF4 activity.
Main Results:
- EF4 is stored at the E. coli cell membrane and released into the cytoplasm under high ionic strength or low temperatures.
- Wild-type E. coli outcompetes EF4-deficient mutants under these stress conditions.
- EF4 enhances protein synthesis fivefold under stress, likely by resolving aberrant ribosomal states.
Conclusions:
- EF4 plays a crucial role in bacterial survival under environmental stress.
- The ability of EF4 to remobilize stalled ribosomes provides a significant selective advantage.
- This selective advantage explains the widespread presence and conservation of EF4 in nature.
Related Concept Videos
02:07Improving Translational Accuracy
Base complementarity between the three base pairs of mRNA codon and the tRNA anticodon is not a failsafe mechanism. Inaccuracies can range from a single mismatch to no correct base pairing at all. The free energy difference between the correct and nearly correct base pairs can be as small as 3 kcal/ mol. With complementarity being the only proofreading step, the estimated error frequency would be one wrong amino acid in every 100 amino acids incorporated. However, error frequencies observed in...
01:23Stringent Response in E. coli
Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
02:35Transcription Elongation Factors
Transcription elongation is a dynamic process that alters depending upon the sequence heterogeneity of the DNA being transcribed. Hence, it is not surprising that the elongation complex's composition also varies along the way while transcribing a gene.
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
02:35Transcription Elongation Factors
Transcription elongation is a dynamic process that alters depending upon the sequence heterogeneity of the DNA being transcribed. Hence, it is not surprising that the elongation complex's composition also varies along the way while transcribing a gene.
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
01:58Mechanical Protein Functions
Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical forces and proteins that are subjected to mechanical forces. Proteins providing mechanical support to the structure of the cell, such as keratin, are subjected to mechanical force, whereas proteins involved in cell movement and transport of molecules across cell membranes, such as an ion pump, are examples of generating mechanical force.
02:28Leaky Scanning
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...