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Journal Article

Elongation factor 4 (EF4/LepA) accelerates protein synthesis at increased Mg2+ concentrations

MPS-Authors
http://pubman.mpdl.mpg.de/cone/persons/resource/persons50464

Pech,  M.
Dept. of Computational Molecular Biology (Head: Martin Vingron), Max Planck Institute for Molecular Genetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons50654

Yamamoto,  H.
Dept. of Human Molecular Genetics (Head: Hans-Hilger Ropers), Max Planck Institute for Molecular Genetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons50475

Qin,  Y.
Ribosomes, Max Planck Institute for Molecular Genetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons50444

Nierhaus,  K. H.
Ribosomes, Max Planck Institute for Molecular Genetics, Max Planck Society;

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Citation

Pech, M., Karim, Z., Yamamoto, H., Kitakawa, M., Qin, Y., & Nierhaus, K. H. (2011). Elongation factor 4 (EF4/LepA) accelerates protein synthesis at increased Mg2+ concentrations. Proc Natl Acad Sci U S A, 108(8), 3199-203. Retrieved from http://www.pnas.org/content/108/8/3199.full.pdf.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0010-77F4-1
Abstract
Elongation factor 4 (EF4) is one of the most conserved proteins present in bacteria as well as in mitochondria and chloroplasts of eukaryotes. Although EF4 has the unique ability to catalyze the back-translocation reaction on posttranslocation state ribosomes, the physiological role of EF4 remains unclear. Here we demonstrate that EF4 is stored at the membrane of Escherichia coli cells and released into the cytoplasm upon conditions of high ionic strength or low temperature. Under such conditions, wild-type E. coli cells overgrow mutant cells lacking the EF4 gene within 5-10 generations. Elevated intracellular Mg(2+) concentrations or low temperature retard bacterial growth and inhibit protein synthesis, probably because of formation of aberrant elongating ribosomal states. We suggest that EF4 binds to these stuck ribosomes and remobilizes them, consistent with the EF4-dependent enhancement (fivefold) in protein synthesis observed under these unfavorable conditions. The strong selective advantage conferred by the presence of EF4 at high intracellular ionic strength or low temperatures explains the ubiquitous distribution and high conservation of EF4.