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.[1] Bacteria and eukaryotes use elongation factors that are largely homologous to each other, but with distinct structures and different research nomenclatures.[2]

"EF2" and "EF-2" redirect here. For the tornado intensity rating, see Enhanced Fujita scale § Parameters.
EF-Tu with tRNA. Taken from PDB Molecule of the Month Elongation factors, September 2006.

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). In eukaryotes the rate is about two amino acids per second (about 6 nucleotides read per second). Elongation factors play a role in orchestrating the events of this process, and in ensuring the high accuracy translation at these speeds.

Nomenclature of homologous EFs
Elongation factors
BacterialEukaryotic/ArchaealFunction
EF-TueEF-1 subunit α[2]mediates the entry of the aminoacyl tRNA into a free site of the ribosome.[4]
EF-TseEF-1 subunit βγ[2]serves as the guanine nucleotide exchange factor for EF-Tu, catalyzing the release of GDP from EF-Tu.[2]
EF-GeEF-2catalyzes 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-PEIF5Apossibly stimulates formation of peptide bonds and resolves stalls.[6]
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.

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.[9]

As a target

Elongation factors are targets for the toxins of some pathogens. For instance, Corynebacterium diphtheriae produces its 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.[10]

gollark: Also, I have no idea what an "objective → semantic buffer" is and I think you're underestimating the difficulty of implementing whatever it is.
gollark: I can't actually source this, having checked *at least* two internet things.
gollark: In any case, I am not a linguist, but I think it's technically possible to produce an AST from English, or something like that, but really impractical. There is no regular grammar, words can't be cleanly mapped to concepts because they carry connotations pulled in from common discourse and the context surrounding them, many of them mean multiple things, you have to be able to resolve pronouns and references to past text, etc.
gollark: I am not aware of there being 22 base units of words or whatever.
gollark: What?

References
  1. Parker, J. (2001). "Elongation Factors; Translation". Encyclopedia of Genetics: 610–611. doi:10.1006/rwgn.2001.0402. ISBN 9780122270802.
  2. 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.
  3. 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.
  4. 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.
  5. 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. 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.
  7. 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.
  8. 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.
  9. 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). doi:10.1186/1471-2148-11-22.
  10. 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
  • Alberts, B. et al. (2002). Molecular Biology of the Cell, 4th ed. New York: Garland Science. ISBN 0-8153-3218-1.
  • Berg, J. M. et al. (2002). Biochemistry, 5th ed. New York: W.H. Freeman and Company. ISBN 0-7167-3051-0.
  • Singh, B. D. (2002). Fundamentals of Genetics, New Delhi, India: Kalyani Publishers. ISBN 81-7663-109-4.
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