Summary
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 edit
| 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 edit
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 edit
- ^ Parker, J. (2001). "Elongation Factors; Translation". Encyclopedia of Genetics. pp. 610–611. doi:10.1006/rwgn.2001.0402. ISBN 9780122270802.
- ^ a b c d 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. PMC 3374885. 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. PMC 5477533. PMID 28480640.
- ^ Weijland A, Harmark K, Cool RH, Anborgh PH, Parmeggiani A (March 1992). "Elongation factor Tu: a molecular switch in protein biosynthesis". Molecular Microbiology. 6 (6): 683–8. 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. S2CID 4795260.
- ^ a b 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. S2CID 25447826.
- ^ 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. PMC 1939882. 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". www.genome.jp.
- ^ 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. PMC 3037878. PMID 21255425.
- ^ Lee H, Iglewski WJ (1984). "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. Bibcode:1984PNAS...81.2703L. doi:10.1073/pnas.81.9.2703. PMC 345138. PMID 6326138.
Further reading edit
- 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 edit
- nobelprize.org Explaining the function of eukaryotic elongation factors
- Elongation+Factor at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- Peptide+Elongation+Factor+G at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- Peptide+Elongation+Factor+Tu at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- EC 3.6.5.3