Biology:Elongation factor
Elongation factors are a set of proteins that function at the ribosome, during protein synthesis, to facilitate translational elongation from the formation of the first to the last peptide bond of a growing polypeptide. Most common elongation factors in prokaryotes are EF-Tu, EF-Ts, EF-G.[1] Bacteria and eukaryotes use elongation factors that are largely homologous to each other, but with distinct structures and different research nomenclatures.[2]
Elongation is the most rapid step in translation.[3] In bacteria, it proceeds at a rate of 15 to 20 amino acids added per second (about 45-60 nucleotides per second).[citation needed] In eukaryotes the rate is about two amino acids per second (about 6 nucleotides read per second).[citation needed] Elongation factors play a role in orchestrating the events of this process, and in ensuring the high accuracy translation at these speeds.[citation needed]
Nomenclature of homologous EFs
| Bacterial | Eukaryotic/Archaeal | Function |
|---|---|---|
| EF-Tu | eEF-1A (α)[2] | mediates the entry of the aminoacyl tRNA into a free site of the ribosome.[4] |
| EF-Ts | eEF-1B (βγ)[2] | serves as the guanine nucleotide exchange factor for EF-Tu, catalyzing the release of GDP from EF-Tu.[2] |
| EF-G | eEF-2 | catalyzes the translocation of the tRNA and mRNA down the ribosome at the end of each round of polypeptide elongation. Causes large conformation changes.[5] |
| EF-P | eIF-5A | possibly stimulates formation of peptide bonds and resolves stalls.[6] |
| EF-4 | (None) | Proofreading |
| Note that EIF5A, the archaeal and eukaryotic homolog to EF-P, was named as an initiation factor but now considered an elongation factor as well.[6] | ||
In addition to their cytoplasmic machinery, eukaryotic mitochondria and plastids have their own translation machinery, each with their own set of bacterial-type elongation factors.[7][8] In humans, they include TUFM, TSFM, GFM1, GFM2, GUF1; the nominal release factor MTRFR may also play a role in elongation.[9]
In bacteria, selenocysteinyl-tRNA requires a special elongation factor SelB (P14081) related to EF-Tu. A few homologs are also found in archaea, but the functions are unknown.[10]
As a target
Elongation factors are targets for the toxins of some pathogens. For instance, Corynebacterium diphtheriae produces diphtheria toxin, which alters protein function in the host by inactivating elongation factor (EF-2). This results in the pathology and symptoms associated with diphtheria. Likewise, Pseudomonas aeruginosa exotoxin A inactivates EF-2.[11]
References
- ↑ Parker, J. (2001). "Elongation Factors; Translation". Encyclopedia of Genetics. pp. 610–611. doi:10.1006/rwgn.2001.0402. ISBN 9780122270802.
- ↑ 2.0 2.1 2.2 2.3 Sasikumar, Arjun N.; Perez, Winder B.; Kinzy, Terri Goss (July 2012). "The Many Roles of the Eukaryotic Elongation Factor 1 Complex". Wiley Interdisciplinary Reviews. RNA 3 (4): 543–555. doi:10.1002/wrna.1118. ISSN 1757-7004. PMID 22555874.
- ↑ Prabhakar, Arjun; Choi, Junhong; Wang, Jinfan; Petrov, Alexey; Puglisi, Joseph D. (July 2017). "Dynamic basis of fidelity and speed in translation: Coordinated multistep mechanisms of elongation and termination". Protein Science 26 (7): 1352–1362. doi:10.1002/pro.3190. ISSN 0961-8368. PMID 28480640.
- ↑ "Elongation factor Tu: a molecular switch in protein biosynthesis". Molecular Microbiology 6 (6): 683–8. March 1992. doi:10.1111/j.1365-2958.1992.tb01516.x. PMID 1573997.
- ↑ Jørgensen, R; Ortiz, PA; Carr-Schmid, A; Nissen, P; Kinzy, TG; Andersen, GR (May 2003). "Two crystal structures demonstrate large conformational changes in the eukaryotic ribosomal translocase.". Nature Structural Biology 10 (5): 379–85. doi:10.1038/nsb923. PMID 12692531.
- ↑ 6.0 6.1 Rossi, D; Kuroshu, R; Zanelli, CF; Valentini, SR (2013). "eIF5A and EF-P: two unique translation factors are now traveling the same road.". Wiley Interdisciplinary Reviews. RNA 5 (2): 209–22. doi:10.1002/wrna.1211. PMID 24402910.
- ↑ Manuell, Andrea L; Quispe, Joel; Mayfield, Stephen P; Petsko, Gregory A (7 August 2007). "Structure of the Chloroplast Ribosome: Novel Domains for Translation Regulation". PLOS Biology 5 (8): e209. doi:10.1371/journal.pbio.0050209. PMID 17683199.
- ↑ G C Atkinson; S L Baldauf (2011). "Evolution of elongation factor G and the origins of mitochondrial and chloroplast forms". Molecular Biology and Evolution 28 (3): 1281–92. doi:10.1093/molbev/msq316. PMID 21097998.
- ↑ "KEGG DISEASE: Combined oxidative phosphorylation deficiency". https://www.genome.jp/dbget-bin/www_bget?ds:H00891.
- ↑ Atkinson, Gemma C; Hauryliuk, Vasili; Tenson, Tanel (21 January 2011). "An ancient family of SelB elongation factor-like proteins with a broad but disjunct distribution across archaea". BMC Evolutionary Biology 11 (1): 22. doi:10.1186/1471-2148-11-22. PMID 21255425.
- ↑ "Cellular ADP-ribosyltransferase with the same mechanism of action as diphtheria toxin and Pseudomonas toxin A". Proc. Natl. Acad. Sci. U.S.A. 81 (9): 2703–7. 1984. doi:10.1073/pnas.81.9.2703. PMID 6326138. Bibcode: 1984PNAS...81.2703L.
Further reading
- Alberts, B. et al. (2002). Molecular Biology of the Cell, 4th ed. New York: Garland Science. ISBN:0-8153-3218-1.[page needed]
- Berg, J. M. et al. (2002). Biochemistry, 5th ed. New York: W.H. Freeman and Company. ISBN:0-7167-3051-0.[page needed]
- Singh, B. D. (2002). Fundamentals of Genetics, New Delhi, India: Kalyani Publishers. ISBN:81-7663-109-4.[page needed]
External links
- nobelprize.org Explaining the function of eukaryotic elongation factors
- Elongation+Factor at the US National Library of Medicine Medical Subject Headings (MeSH)
- Peptide+Elongation+Factor+G at the US National Library of Medicine Medical Subject Headings (MeSH)
- Peptide+Elongation+Factor+Tu at the US National Library of Medicine Medical Subject Headings (MeSH)
- EC 3.6.5.3
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