Elongation Factors: Bacterial


Translational elongation factors are extra ribosomal proteins required for the addition of amino acids to the polypeptide being synthesized on the ribosome. Sequence comparisons and high‐resolution structural analyses of these proteins in bacteria have revealed striking homologies among them, with important implications for their evolution and function.

Keywords: elongation factors; protein synthesis; translation; ribosomal

Figure 1.

Crystal structures of EF‐Tu, EF‐Tu·aa‐tRNA and EF‐G. (a) Thermus aquaticusEF‐Tu·GDP (protein data base (PDB) entry 1TUI, Polekhina et al., ). (b) The complex of T. aquaticusEF‐Tu, GMPPNP (a GTP analogue) and yeast phenylalanyl‐tRNAPhe (PDB entry 1TTT; Nissen et al., ). (c) T. thermophilus EF‐G·GDP (PDB entry 1DAR, al‐Karadaghi et al., ). Proteins are portrayed as a tube representing the polypeptide backbone; effector nucleotides and aa‐tRNA are shown as all‐atom ball‐and‐stick. Structurally similar residues of the G domains (on which the structures are aligned) are coloured red, structurally similar residues of domains 2 are blue, the G′ subdomain of EF‐G is cyan, the G″ insertion of EF‐Tu is orange and the rest of the protein is grey. The guanine nucleotides bound to the G domains are yellow, as is the aa‐tRNA, except that the amino acid of the tRNA is magenta and the three anticodon nucleotides are green. (Both figures were made with the program MidasPlus from the Computer Graphics Laboratory, University of California, San Francisco.)

Figure 2.

Crystal structures of the complexes of EF‐Tu and EF‐Ts. (a) The complex in Escherichia coli (PDB entry 1EFU, Kawashima et al., ). (b) The complex in T. thermophilus (PDB entry 1AIP; Wang et al., ) showing the full heterotetramer. The structurally similar residues of the G domains of the two EF‐Tu species (on which the structures are aligned) are red, the structurally similar residues of the domains 2 of EF‐Tu are shown in blue, and the rest of the EF‐Tu polypeptide is grey. The EF‐Ts molecules are coloured pink (shaded differently to distinguish the EF‐Ts monomers on the right), except that the identical and highly conserved amino acids are purple.



al‐Karadaghi S, Ævarsson A, Garber M, Zheltonosova J and Liljas A (1996) The structure of elongation factor G in complex with GDP: conformational flexibility and nucleotide exchange. Structure 4: 555–565.

Andersson SGE and Kurland CG (1995) Genomic evolution drives the evolution of the translation system. Biochemistry and Cell Biology 73: 775–787.

Ævarsson A (1995) Structure‐based sequence alignment of elongation factors Tu and G with related GTPases involved in translation. Journal of Molecular Evolution 41: 1096–1104.

Baldauf SL, Palmer JD and Doolittle WF (1996) The root of the universal tree and the origin of eukaryotes based on elongation factor phylogeny. Proceedings of the National Academy of Sciences of the USA 93: 7749–7754.

Czworkowski J and Moore PB (1997) The conformational properties of elongation factor G and the mechanism of translocation. Biochemistry 36: 10327–10334.

Kawashima T, Berthet‐Colominas C, Wulff M, Cusack S and Leberman R (1996) The structure of the Escherichia coli EF‐Tu·EF‐Ts complex at 2.5 Å resolution. Nature 379: 511–518.

Liljas A (1996) Imprinting through molecular mimicry. Current Biology 6: 247–249.

Moazed D and Noller HF (1989) Intermediate states in the movement of transfer RNA in the ribosome. Nature 342: 142–148.

Nissen P, Kjeldgaard M, Thirup S et al. (1995) Crystal structure of the ternary complex of Phe‐tRNAPhe, EF‐Tu, and a GTP analog. Science 270: 1464–1472.

Polekhina G, Thirup S, Kjeldgaard M et al. (1996) Helix unwinding in the effector region of elongation factor EF‐Tu. Structure 4: 1141–1151.

Wang Y, Jiang Y, Meyering‐Voss M, Sprinzl M and Sigler PB (1997) Crystal structure of the EF‐Tu·EF‐Ts complex from Thermus thermophilus. Nature Structural Biology 4: 650–656.

Further Reading

al‐Karadaghi S, Kristensen O and Liljas A (2000) A decade of progress in understanding the structural basis of protein synthesis. Progress in Biophysics and Molecular Biology 73: 167–193.

Andersen GR, Nissen P and Nyborg J (2003) Elongation factors in protein biosynthesis. Trends in Biochemical Sciences 28: 434–441.

Clark BFC and Nyborg J (1997) The ternary complex of EF‐Tu and its role in protein biosynthesis. Current Opinion in Structural Biology 7: 110–116.

Czworkowski J and Moore PB (1996) The elongation phase of protein synthesis. Progress in Nucleic Acid Research and Molecular Biology 54: 293–332.

Sprang SR (1997) G protein mechanisms: insights from structural analysis. Annual Review of Biochemistry 66: 639–678.

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Czworkowski, John(Jan 2006) Elongation Factors: Bacterial. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0003932]