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. 1997 Dec;17(12):6940–6947. doi: 10.1128/mcb.17.12.6940

Human eukaryotic translation initiation factor 4G (eIF4G) possesses two separate and independent binding sites for eIF4A.

H Imataka 1, N Sonenberg 1
PMCID: PMC232551  PMID: 9372926

Abstract

Mammalian translation initiation factor 4F (eIF4F) consists of three subunits, eIF4A, eIF4E, and eIF4G. eIF4G interacts directly with both eIF4A and eIF4E. The binding site for eIF4E is contained in the amino-terminal third of eIF4G, while the binding site for eIF4A was mapped to the carboxy-terminal third of the molecule. Here we show that human eIF4G possesses two separate eIF4A binding domains in the middle third (amino acids [aa] 478 to 883) and carboxy-terminal third (aa 884 to 1404) of the molecule. The amino acid sequence of the middle portion of eIF4G is well conserved between yeasts and humans. We show that mutations of conserved amino acid stretches in the middle domain abolish or reduce eIF4A binding as well as eIF3 binding. In addition, a separate and nonoverlapping eIF4A binding domain exists in the carboxy-terminal third (aa 1045 to 1404) of eIF4G, which is not present in yeast. The C-terminal two-thirds region (aa 457 to 1404) of eIF4G, containing both eIF4A binding sites, is required for stimulating translation. Neither one of the eIF4A binding domains alone activates translation. In contrast to eIF4G, human p97, a translation inhibitor with homology to eIF4G, binds eIF4A only through the amino-terminal proximal region, which is homologous to the middle domain of eIF4G.

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Selected References

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  1. Allen M. L., Metz A. M., Timmer R. T., Rhoads R. E., Browning K. S. Isolation and sequence of the cDNAs encoding the subunits of the isozyme form of wheat protein synthesis initiation factor 4F. J Biol Chem. 1992 Nov 15;267(32):23232–23236. [PubMed] [Google Scholar]
  2. Altmann M., Blum S., Pelletier J., Sonenberg N., Wilson T. M., Trachsel H. Translation initiation factor-dependent extracts from Saccharomyces cerevisiae. Biochim Biophys Acta. 1990 Aug 27;1050(1-3):155–159. doi: 10.1016/0167-4781(90)90158-x. [DOI] [PubMed] [Google Scholar]
  3. Etchison D., Milburn S. C., Edery I., Sonenberg N., Hershey J. W. Inhibition of HeLa cell protein synthesis following poliovirus infection correlates with the proteolysis of a 220,000-dalton polypeptide associated with eucaryotic initiation factor 3 and a cap binding protein complex. J Biol Chem. 1982 Dec 25;257(24):14806–14810. [PubMed] [Google Scholar]
  4. Fuerst T. R., Niles E. G., Studier F. W., Moss B. Eukaryotic transient-expression system based on recombinant vaccinia virus that synthesizes bacteriophage T7 RNA polymerase. Proc Natl Acad Sci U S A. 1986 Nov;83(21):8122–8126. doi: 10.1073/pnas.83.21.8122. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Goyer C., Altmann M., Lee H. S., Blanc A., Deshmukh M., Woolford J. L., Jr, Trachsel H., Sonenberg N. TIF4631 and TIF4632: two yeast genes encoding the high-molecular-weight subunits of the cap-binding protein complex (eukaryotic initiation factor 4F) contain an RNA recognition motif-like sequence and carry out an essential function. Mol Cell Biol. 1993 Aug;13(8):4860–4874. doi: 10.1128/mcb.13.8.4860. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Haghighat A., Mader S., Pause A., Sonenberg N. Repression of cap-dependent translation by 4E-binding protein 1: competition with p220 for binding to eukaryotic initiation factor-4E. EMBO J. 1995 Nov 15;14(22):5701–5709. doi: 10.1002/j.1460-2075.1995.tb00257.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Haghighat A., Svitkin Y., Novoa I., Kuechler E., Skern T., Sonenberg N. The eIF4G-eIF4E complex is the target for direct cleavage by the rhinovirus 2A proteinase. J Virol. 1996 Dec;70(12):8444–8450. doi: 10.1128/jvi.70.12.8444-8450.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Imataka H., Olsen H. S., Sonenberg N. A new translational regulator with homology to eukaryotic translation initiation factor 4G. EMBO J. 1997 Feb 17;16(4):817–825. doi: 10.1093/emboj/16.4.817. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Lamphear B. J., Kirchweger R., Skern T., Rhoads R. E. Mapping of functional domains in eukaryotic protein synthesis initiation factor 4G (eIF4G) with picornaviral proteases. Implications for cap-dependent and cap-independent translational initiation. J Biol Chem. 1995 Sep 15;270(37):21975–21983. doi: 10.1074/jbc.270.37.21975. [DOI] [PubMed] [Google Scholar]
  10. Lamphear B. J., Rhoads R. E. A single amino acid change in protein synthesis initiation factor 4G renders cap-dependent translation resistant to picornaviral 2A proteases. Biochemistry. 1996 Dec 10;35(49):15726–15733. doi: 10.1021/bi961864t. [DOI] [PubMed] [Google Scholar]
  11. Lazaris-Karatzas A., Smith M. R., Frederickson R. M., Jaramillo M. L., Liu Y. L., Kung H. F., Sonenberg N. Ras mediates translation initiation factor 4E-induced malignant transformation. Genes Dev. 1992 Sep;6(9):1631–1642. doi: 10.1101/gad.6.9.1631. [DOI] [PubMed] [Google Scholar]
  12. Levy-Strumpf N., Deiss L. P., Berissi H., Kimchi A. DAP-5, a novel homolog of eukaryotic translation initiation factor 4G isolated as a putative modulator of gamma interferon-induced programmed cell death. Mol Cell Biol. 1997 Mar;17(3):1615–1625. doi: 10.1128/mcb.17.3.1615. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Liebig H. D., Ziegler E., Yan R., Hartmuth K., Klump H., Kowalski H., Blaas D., Sommergruber W., Frasel L., Lamphear B. Purification of two picornaviral 2A proteinases: interaction with eIF-4 gamma and influence on in vitro translation. Biochemistry. 1993 Jul 27;32(29):7581–7588. doi: 10.1021/bi00080a033. [DOI] [PubMed] [Google Scholar]
  14. Mader S., Lee H., Pause A., Sonenberg N. The translation initiation factor eIF-4E binds to a common motif shared by the translation factor eIF-4 gamma and the translational repressors 4E-binding proteins. Mol Cell Biol. 1995 Sep;15(9):4990–4997. doi: 10.1128/mcb.15.9.4990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Metz A. M., Browning K. S. Mutational analysis of the functional domains of the large subunit of the isozyme form of wheat initiation factor eIF4F. J Biol Chem. 1996 Dec 6;271(49):31033–31036. doi: 10.1074/jbc.271.49.31033. [DOI] [PubMed] [Google Scholar]
  16. Nielsen P. J., Trachsel H. The mouse protein synthesis initiation factor 4A gene family includes two related functional genes which are differentially expressed. EMBO J. 1988 Jul;7(7):2097–2105. doi: 10.1002/j.1460-2075.1988.tb03049.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Pain V. M. Initiation of protein synthesis in eukaryotic cells. Eur J Biochem. 1996 Mar 15;236(3):747–771. doi: 10.1111/j.1432-1033.1996.00747.x. [DOI] [PubMed] [Google Scholar]
  18. Pause A., Méthot N., Svitkin Y., Merrick W. C., Sonenberg N. Dominant negative mutants of mammalian translation initiation factor eIF-4A define a critical role for eIF-4F in cap-dependent and cap-independent initiation of translation. EMBO J. 1994 Mar 1;13(5):1205–1215. doi: 10.1002/j.1460-2075.1994.tb06370.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Pestova T. V., Shatsky I. N., Hellen C. U. Functional dissection of eukaryotic initiation factor 4F: the 4A subunit and the central domain of the 4G subunit are sufficient to mediate internal entry of 43S preinitiation complexes. Mol Cell Biol. 1996 Dec;16(12):6870–6878. doi: 10.1128/mcb.16.12.6870. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Rozen F., Edery I., Meerovitch K., Dever T. E., Merrick W. C., Sonenberg N. Bidirectional RNA helicase activity of eucaryotic translation initiation factors 4A and 4F. Mol Cell Biol. 1990 Mar;10(3):1134–1144. doi: 10.1128/mcb.10.3.1134. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Shaughnessy J. D., Jr, Jenkins N. A., Copeland N. G. cDNA cloning, expression analysis, and chromosomal localization of a gene with high homology to wheat eIF-(iso)4F and mammalian eIF-4G. Genomics. 1997 Jan 15;39(2):192–197. doi: 10.1006/geno.1996.4502. [DOI] [PubMed] [Google Scholar]
  22. Smith R. F., Smith T. F. Pattern-induced multi-sequence alignment (PIMA) algorithm employing secondary structure-dependent gap penalties for use in comparative protein modelling. Protein Eng. 1992 Jan;5(1):35–41. doi: 10.1093/protein/5.1.35. [DOI] [PubMed] [Google Scholar]
  23. Yamanaka S., Poksay K. S., Arnold K. S., Innerarity T. L. A novel translational repressor mRNA is edited extensively in livers containing tumors caused by the transgene expression of the apoB mRNA-editing enzyme. Genes Dev. 1997 Feb 1;11(3):321–333. doi: 10.1101/gad.11.3.321. [DOI] [PubMed] [Google Scholar]
  24. Yan R., Rychlik W., Etchison D., Rhoads R. E. Amino acid sequence of the human protein synthesis initiation factor eIF-4 gamma. J Biol Chem. 1992 Nov 15;267(32):23226–23231. [PubMed] [Google Scholar]

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