Login
Login

elongation factor

{{distinguish|Relative elongation}}

{{Redirect2|EF2|EF-2|the tornado intensity rating|Enhanced Fujita scale#Parameters}}

{{more citations needed|date=October 2019}}

{{Short description|Proteins functioning in translation}}

Image:081-EF-Tu-1ttt.jpg

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.{{cite encyclopedia |last1=Parker |first1=J. |title=Elongation Factors; Translation |encyclopedia=Encyclopedia of Genetics |date=2001 |pages=610–611 |doi=10.1006/rwgn.2001.0402|isbn=9780122270802 }} Bacteria and eukaryotes use elongation factors that are largely homologous to each other, but with distinct structures and different research nomenclatures.{{Cite journal|last1=Sasikumar|first1=Arjun N.|last2=Perez|first2=Winder B.|last3=Kinzy|first3=Terri Goss|date=July 2012|title=The Many Roles of the Eukaryotic Elongation Factor 1 Complex|journal=Wiley Interdisciplinary Reviews. RNA|volume=3|issue=4|pages=543–555|doi=10.1002/wrna.1118|issn=1757-7004|pmc=3374885|pmid=22555874}}

Elongation is the most rapid step in translation.{{Cite journal|last1=Prabhakar|first1=Arjun|last2=Choi|first2=Junhong|last3=Wang|first3=Jinfan|last4=Petrov|first4=Alexey|last5=Puglisi|first5=Joseph D.|date=July 2017|title=Dynamic basis of fidelity and speed in translation: Coordinated multistep mechanisms of elongation and termination|journal=Protein Science |volume=26|issue=7|pages=1352–1362|doi=10.1002/pro.3190|issn=0961-8368|pmc=5477533|pmid=28480640}} In bacteria, it proceeds at a rate of 15 to 20 amino acids added per second (about 45-60 nucleotides per second).{{citation needed|date=October 2019}} In eukaryotes the rate is about two amino acids per second (about 6 nucleotides read per second).{{citation needed|date=October 2019}} Elongation factors play a role in orchestrating the events of this process, and in ensuring the high accuracy translation at these speeds.{{citation needed|date=October 2019}}

Nomenclature of homologous EFs

class=wikitable

|+Elongation factors

BacterialEukaryotic/ArchaealFunction
EF-TueEF-1A (α)mediates the entry of the aminoacyl tRNA into a free site of the ribosome.{{cite journal | vauthors = Weijland A, Harmark K, Cool RH, Anborgh PH, Parmeggiani A | title = Elongation factor Tu: a molecular switch in protein biosynthesis | journal = Molecular Microbiology | volume = 6 | issue = 6 | pages = 683–8 | date = March 1992 | pmid = 1573997 | doi = 10.1111/j.1365-2958.1992.tb01516.x | doi-access = free }}
EF-TseEF-1B (βγ)serves as the guanine nucleotide exchange factor for EF-Tu, catalyzing the release of GDP from EF-Tu.
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.{{cite journal |last1=Jørgensen |first1=R |last2=Ortiz |first2=PA |last3=Carr-Schmid |first3=A |last4=Nissen |first4=P |last5=Kinzy |first5=TG |last6=Andersen |first6=GR |title=Two crystal structures demonstrate large conformational changes in the eukaryotic ribosomal translocase. |journal=Nature Structural Biology |date=May 2003 |volume=10 |issue=5 |pages=379–85 |doi=10.1038/nsb923 |pmid=12692531|s2cid=4795260 }}
EF-PeIF-5Apossibly stimulates formation of peptide bonds and resolves stalls.{{cite journal |last1=Rossi |first1=D |last2=Kuroshu |first2=R |last3=Zanelli |first3=CF |last4=Valentini |first4=SR |title=eIF5A and EF-P: two unique translation factors are now traveling the same road. |journal=Wiley Interdisciplinary Reviews. RNA |date=2013 |volume=5 |issue=2 |pages=209–22 |doi=10.1002/wrna.1211 |pmid=24402910|s2cid=25447826 }}
EF-4(None)Proofreading
colspan=3 | 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.

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.{{cite journal |doi-access=free |last1=Manuell |first1=Andrea L |last2=Quispe |first2=Joel |last3=Mayfield |first3=Stephen P |last4=Petsko |first4=Gregory A |title=Structure of the Chloroplast Ribosome: Novel Domains for Translation Regulation |journal=PLOS Biology |date=7 August 2007 |volume=5 |issue=8 |pages=e209 |doi=10.1371/journal.pbio.0050209|pmid=17683199 |pmc=1939882 }}{{Cite journal|author1=G C Atkinson |author2=S L Baldauf | title=Evolution of elongation factor G and the origins of mitochondrial and chloroplast forms| journal=Molecular Biology and Evolution| year=2011| volume=28| issue=3| pages=1281–92| pmid = 21097998| doi=10.1093/molbev/msq316 | doi-access=free}} In humans, they include TUFM, TSFM, GFM1, GFM2, GUF1; the nominal release factor MTRFR may also play a role in elongation.{{cite web |title=KEGG DISEASE: Combined oxidative phosphorylation deficiency |url=https://www.genome.jp/dbget-bin/www_bget?ds:H00891 |website=www.genome.jp}}

In bacteria, selenocysteinyl-tRNA requires a special elongation factor SelB ({{UniProt|P14081}}) related to EF-Tu. A few homologs are also found in archaea, but the functions are unknown.{{cite journal |last1=Atkinson |first1=Gemma C |last2=Hauryliuk |first2=Vasili |last3=Tenson |first3=Tanel |title=An ancient family of SelB elongation factor-like proteins with a broad but disjunct distribution across archaea |journal=BMC Evolutionary Biology |date=21 January 2011 |volume=11 |issue=1 |page=22 |doi=10.1186/1471-2148-11-22|pmid=21255425 |pmc=3037878 |doi-access=free }}

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.{{cite journal | vauthors = Lee H, Iglewski WJ | year = 1984 | title = Cellular ADP-ribosyltransferase with the same mechanism of action as diphtheria toxin and Pseudomonas toxin A | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 81 | pages = 2703–7 | pmid = 6326138 | doi = 10.1073/pnas.81.9.2703 | issue = 9 | pmc = 345138 | bibcode = 1984PNAS...81.2703L | doi-access = free }}

References

{{reflist}}

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|date=October 2019}}
  • Berg, J. M. et al. (2002). Biochemistry, 5th ed. New York: W.H. Freeman and Company. {{ISBN|0-7167-3051-0}}.{{page needed|date=October 2019}}
  • Singh, B. D. (2002). Fundamentals of Genetics, New Delhi, India: Kalyani Publishers. {{ISBN|81-7663-109-4}}.{{page needed|date=October 2019}}

External links

  • [https://web.archive.org/web/20121015234642/http://www.nobelprize.org/educational/medicine/dna/a/translation/elongation.html nobelprize.org] Explaining the function of eukaryotic elongation factors
  • {{MeshName|Elongation+Factor}}
  • {{MeshName|Peptide+Elongation+Factor+G}}
  • {{MeshName|Peptide+Elongation+Factor+Tu}}
  • {{EC number|3.6.5.3}}

{{GeneticTranslation}}

{{GTPases}}

Category:Protein biosynthesis