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Elongation factor

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Not to be confused with Relative elongation.
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Proteins functioning in translation
Ternary complex of EF-Tu (blue), tRNA (red) and GTP (yellow). Taken from PDB Molecule of the Month Elongation factors , September 2006.

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

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Elongation factors
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 (β γ)[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

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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

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  1. ^ Parker, J. (2001). "Elongation Factors; Translation". Encyclopedia of Genetics. pp. 610–611. doi:10.1006/rwgn.2001.0402. ISBN 9780122270802.
  2. ^ 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.
  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. S2CID 4795260.
  6. ^ 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.
  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. ^ "KEGG DISEASE: Combined oxidative phosphorylation deficiency". www.genome.jp.
  10. ^ 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年11月22日 . PMC 3037878 . PMID 21255425.
  11. ^ 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

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[edit ]
Proteins
Initiation factor
Bacterial
Mitochondrial
Archaeal
Eukaryotic
eIF1
eIF2
eIF3
eIF4
eIF5
eIF6
Elongation factor
Bacterial/Mitochondrial
Archaeal/Eukaryotic
Release factor
Ribosomal Proteins
Cytoplasmic
60S subunit
40S subunit
Mitochondrial
39S subunit
28S subunit
Other concepts
3.6.1
3.6.2
3.6.3-4: ATPase
3.6.3
Cu++ (3.6.3.4)
Ca+ (3.6.3.8)
Na+/K+ (3.6.3.9)
H+/K+ (3.6.3.10)
Other P-type ATPase
3.6.4
3.6.5: GTPase
3.6.5.1: Heterotrimeric G protein
3.6.5.2: Small GTPase > Ras superfamily
3.6.5.3: Protein-synthesizing GTPase
3.6.5.5-6: Polymerization motors

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