Skip to main content
PMC home page
The EMBO Journal logoLink to The EMBO Journal
. 1996 Mar 15;15(6):1371–1382.

The C-terminal domain of eukaryotic protein synthesis initiation factor (eIF) 4G is sufficient to support cap-independent translation in the absence of eIF4E.

T Ohlmann 1, M Rau 1, V M Pain 1, S J Morley 1
PMCID: PMC450042  PMID: 8635470

Abstract

The foot and mouth disease virus, a picornavirus, encodes two forms of a cysteine proteinase (leader or L protease) that bisects the EIF4G polypeptide of the initiation factor complex eIF4F into N-terminal (Nt) and C-terminal (Ct) domains. Previously we showed that, although in vitro cleavage of the translation initiation factor, eIF4G, with L protease decreases cap-dependent translation, the cleavage products themselves may directly promote cap-dependent protein synthesis. We now demonstrate that translation of uncapped mRNAs normally exhibits a strong requirement for eIF4F. However, this dependence is abolished when eIF4G is cleaved, with the Ct domain capable of supporting translation in the absence of the Nt domain. In contrast, the efficient translation of the second cistron of bicistronic mRNAs, directed by two distinct Internal Ribosome Entry Segments (IRES), exhibits no requirement for eIF4E but is dependent upon either intact eIF4G or the Ct domain. These results demonstrate that: (i) the apparent requirement for eIF4F for internal initiation on IRES-driven mRNAs can be fulfilled by the Ct proteolytic cleavage product; (ii) when eIF4G is cleaved, the Ct domain can also support cap-independent translation of cellular mRNAs not possessing an IRES element, in the absence of eIF4E; and (iii) when eIF4G is intact, translation of cellular mRNAs, whether capped or uncapped, is strictly dependent upon eIF4E. These data complement recent work in other laboratories defining the binding sites for other initiation factors on the eIF4G molecule.

Full text

PDF
1371

Images in this article

1373Image
on p.1373
1373Image
on p.1373
1374Image
on p.1374
1376Image
on p.1376
1377Image
on p.1377
1378Image
on p.1378

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. 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]
  2. Anthony D. D., Merrick W. C. Eukaryotic initiation factor (eIF)-4F. Implications for a role in internal initiation of translation. J Biol Chem. 1991 Jun 5;266(16):10218–10226. [PubMed] [Google Scholar]
  3. Belsham G. J., Brangwyn J. K. A region of the 5' noncoding region of foot-and-mouth disease virus RNA directs efficient internal initiation of protein synthesis within cells: involvement with the role of L protease in translational control. J Virol. 1990 Nov;64(11):5389–5395. doi: 10.1128/jvi.64.11.5389-5395.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Bonneau A. M., Sonenberg N. Proteolysis of the p220 component of the cap-binding protein complex is not sufficient for complete inhibition of host cell protein synthesis after poliovirus infection. J Virol. 1987 Apr;61(4):986–991. doi: 10.1128/jvi.61.4.986-991.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Borman A. M., Bailly J. L., Girard M., Kean K. M. Picornavirus internal ribosome entry segments: comparison of translation efficiency and the requirements for optimal internal initiation of translation in vitro. Nucleic Acids Res. 1995 Sep 25;23(18):3656–3663. doi: 10.1093/nar/23.18.3656. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Buckley B., Ehrenfeld E. The cap-binding protein complex in uninfected and poliovirus-infected HeLa cells. J Biol Chem. 1987 Oct 5;262(28):13599–13606. [PubMed] [Google Scholar]
  7. Dahl H. H., Blair G. E. Purification of four eukaryotic initiation factors required for natural mRNA translation. Methods Enzymol. 1979;60:87–101. doi: 10.1016/s0076-6879(79)60009-5. [DOI] [PubMed] [Google Scholar]
  8. Devaney M. A., Vakharia V. N., Lloyd R. E., Ehrenfeld E., Grubman M. J. Leader protein of foot-and-mouth disease virus is required for cleavage of the p220 component of the cap-binding protein complex. J Virol. 1988 Nov;62(11):4407–4409. doi: 10.1128/jvi.62.11.4407-4409.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. 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]
  10. Etchison D., Smith K. Variations in cap-binding complexes from uninfected and poliovirus-infected HeLa cells. J Biol Chem. 1990 May 5;265(13):7492–7500. [PubMed] [Google Scholar]
  11. Fletcher L., Corbin S. D., Browning K. S., Ravel J. M. The absence of a m7G cap on beta-globin mRNA and alfalfa mosaic virus RNA 4 increases the amounts of initiation factor 4F required for translation. J Biol Chem. 1990 Nov 15;265(32):19582–19587. [PubMed] [Google Scholar]
  12. Hambidge S. J., Sarnow P. Translational enhancement of the poliovirus 5' noncoding region mediated by virus-encoded polypeptide 2A. Proc Natl Acad Sci U S A. 1992 Nov 1;89(21):10272–10276. doi: 10.1073/pnas.89.21.10272. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hunt S. L., Kaminski A., Jackson R. J. The influence of viral coding sequences on the efficiency of internal initiation of translation of cardiovirus RNAs. Virology. 1993 Dec;197(2):801–807. doi: 10.1006/viro.1993.1661. [DOI] [PubMed] [Google Scholar]
  14. Jackson R. J., Howell M. T., Kaminski A. The novel mechanism of initiation of picornavirus RNA translation. Trends Biochem Sci. 1990 Dec;15(12):477–483. doi: 10.1016/0968-0004(90)90302-r. [DOI] [PubMed] [Google Scholar]
  15. Jackson R. J., Hunt S. L., Gibbs C. L., Kaminski A. Internal initiation of translation of picornavirus RNAs. Mol Biol Rep. 1994 May;19(3):147–159. doi: 10.1007/BF00986957. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Jackson R. J., Hunt S. L., Reynolds J. E., Kaminski A. Cap-dependent and cap-independent translation: operational distinctions and mechanistic interpretations. Curr Top Microbiol Immunol. 1995;203:1–29. doi: 10.1007/978-3-642-79663-0_1. [DOI] [PubMed] [Google Scholar]
  17. Jackson R. J., Hunt T. Preparation and use of nuclease-treated rabbit reticulocyte lysates for the translation of eukaryotic messenger RNA. Methods Enzymol. 1983;96:50–74. doi: 10.1016/s0076-6879(83)96008-1. [DOI] [PubMed] [Google Scholar]
  18. Kirchweger R., Ziegler E., Lamphear B. J., Waters D., Liebig H. D., Sommergruber W., Sobrino F., Hohenadl C., Blaas D., Rhoads R. E. Foot-and-mouth disease virus leader proteinase: purification of the Lb form and determination of its cleavage site on eIF-4 gamma. J Virol. 1994 Sep;68(9):5677–5684. doi: 10.1128/jvi.68.9.5677-5684.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. 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]
  20. Lamphear B. J., Yan R., Yang F., Waters D., Liebig H. D., Klump H., Kuechler E., Skern T., Rhoads R. E. Mapping the cleavage site in protein synthesis initiation factor eIF-4 gamma of the 2A proteases from human Coxsackievirus and rhinovirus. J Biol Chem. 1993 Sep 15;268(26):19200–19203. [PubMed] [Google Scholar]
  21. 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]
  22. Lin T. A., Kong X., Haystead T. A., Pause A., Belsham G., Sonenberg N., Lawrence J. C., Jr PHAS-I as a link between mitogen-activated protein kinase and translation initiation. Science. 1994 Oct 28;266(5185):653–656. doi: 10.1126/science.7939721. [DOI] [PubMed] [Google Scholar]
  23. Macadam A. J., Ferguson G., Fleming T., Stone D. M., Almond J. W., Minor P. D. Role for poliovirus protease 2A in cap independent translation. EMBO J. 1994 Feb 15;13(4):924–927. doi: 10.1002/j.1460-2075.1994.tb06336.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Macejak D. G., Sarnow P. Internal initiation of translation mediated by the 5' leader of a cellular mRNA. Nature. 1991 Sep 5;353(6339):90–94. doi: 10.1038/353090a0. [DOI] [PubMed] [Google Scholar]
  25. 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]
  26. Merrick W. C. Mechanism and regulation of eukaryotic protein synthesis. Microbiol Rev. 1992 Jun;56(2):291–315. doi: 10.1128/mr.56.2.291-315.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Meyer K., Petersen A., Niepmann M., Beck E. Interaction of eukaryotic initiation factor eIF-4B with a picornavirus internal translation initiation site. J Virol. 1995 May;69(5):2819–2824. doi: 10.1128/jvi.69.5.2819-2824.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Morley S. J., Hershey J. W. A fractionated reticulocyte lysate retains high efficiency for protein synthesis. Biochimie. 1990 Apr;72(4):259–264. doi: 10.1016/0300-9084(90)90081-q. [DOI] [PubMed] [Google Scholar]
  29. Morley S. J., Pain V. M. Hormone-induced meiotic maturation in Xenopus oocytes occurs independently of p70s6k activation and is associated with enhanced initiation factor (eIF)-4F phosphorylation and complex formation. J Cell Sci. 1995 Apr;108(Pt 4):1751–1760. doi: 10.1242/jcs.108.4.1751. [DOI] [PubMed] [Google Scholar]
  30. Morley S. J. Signal transduction mechanisms in the regulation of protein synthesis. Mol Biol Rep. 1994 May;19(3):221–231. doi: 10.1007/BF00986964. [DOI] [PubMed] [Google Scholar]
  31. Oh S. K., Scott M. P., Sarnow P. Homeotic gene Antennapedia mRNA contains 5'-noncoding sequences that confer translational initiation by internal ribosome binding. Genes Dev. 1992 Sep;6(9):1643–1653. doi: 10.1101/gad.6.9.1643. [DOI] [PubMed] [Google Scholar]
  32. Ohlmann T., Rau M., Morley S. J., Pain V. M. Proteolytic cleavage of initiation factor eIF-4 gamma in the reticulocyte lysate inhibits translation of capped mRNAs but enhances that of uncapped mRNAs. Nucleic Acids Res. 1995 Feb 11;23(3):334–340. doi: 10.1093/nar/23.3.334. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Pause A., Belsham G. J., Gingras A. C., Donzé O., Lin T. A., Lawrence J. C., Jr, Sonenberg N. Insulin-dependent stimulation of protein synthesis by phosphorylation of a regulator of 5'-cap function. Nature. 1994 Oct 27;371(6500):762–767. doi: 10.1038/371762a0. [DOI] [PubMed] [Google Scholar]
  34. 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]
  35. Poole T. L., Wang C., Popp R. A., Potgieter L. N., Siddiqui A., Collett M. S. Pestivirus translation initiation occurs by internal ribosome entry. Virology. 1995 Jan 10;206(1):750–754. doi: 10.1016/s0042-6822(95)80003-4. [DOI] [PubMed] [Google Scholar]
  36. Pérez L., Carrasco L. Lack of direct correlation between p220 cleavage and the shut-off of host translation after poliovirus infection. Virology. 1992 Jul;189(1):178–186. doi: 10.1016/0042-6822(92)90693-j. [DOI] [PubMed] [Google Scholar]
  37. Rhoads R. E. Regulation of eukaryotic protein synthesis by initiation factors. J Biol Chem. 1993 Feb 15;268(5):3017–3020. [PubMed] [Google Scholar]
  38. Scheper G. C., Voorma H. O., Thomas A. A. Eukaryotic initiation factors-4E and -4F stimulate 5' cap-dependent as well as internal initiation of protein synthesis. J Biol Chem. 1992 Apr 15;267(11):7269–7274. [PubMed] [Google Scholar]
  39. Thomas A. A., Scheper G. C., Kleijn M., De Boer M., Voorma H. O. Dependence of the adenovirus tripartite leader on the p220 subunit of eukaryotic initiation factor 4F during in vitro translation. Effect of p220 cleavage by foot-and-mouth-disease-virus L-protease on in vitro translation. Eur J Biochem. 1992 Jul 15;207(2):471–477. doi: 10.1111/j.1432-1033.1992.tb17073.x. [DOI] [PubMed] [Google Scholar]
  40. Thomas A. A., ter Haar E., Wellink J., Voorma H. O. Cowpea mosaic virus middle component RNA contains a sequence that allows internal binding of ribosomes and that requires eukaryotic initiation factor 4F for optimal translation. J Virol. 1991 Jun;65(6):2953–2959. doi: 10.1128/jvi.65.6.2953-2959.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Tsukiyama-Kohara K., Iizuka N., Kohara M., Nomoto A. Internal ribosome entry site within hepatitis C virus RNA. J Virol. 1992 Mar;66(3):1476–1483. doi: 10.1128/jvi.66.3.1476-1483.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  42. Vagner S., Gensac M. C., Maret A., Bayard F., Amalric F., Prats H., Prats A. C. Alternative translation of human fibroblast growth factor 2 mRNA occurs by internal entry of ribosomes. Mol Cell Biol. 1995 Jan;15(1):35–44. doi: 10.1128/mcb.15.1.35. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Wang C., Sarnow P., Siddiqui A. Translation of human hepatitis C virus RNA in cultured cells is mediated by an internal ribosome-binding mechanism. J Virol. 1993 Jun;67(6):3338–3344. doi: 10.1128/jvi.67.6.3338-3344.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Whetter L. E., Day S. P., Elroy-Stein O., Brown E. A., Lemon S. M. Low efficiency of the 5' nontranslated region of hepatitis A virus RNA in directing cap-independent translation in permissive monkey kidney cells. J Virol. 1994 Aug;68(8):5253–5263. doi: 10.1128/jvi.68.8.5253-5263.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. 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]
  46. Ziegler E., Borman A. M., Kirchweger R., Skern T., Kean K. M. Foot-and-mouth disease virus Lb proteinase can stimulate rhinovirus and enterovirus IRES-driven translation and cleave several proteins of cellular and viral origin. J Virol. 1995 Jun;69(6):3465–3474. doi: 10.1128/jvi.69.6.3465-3474.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The EMBO Journal are provided here courtesy of Nature Publishing Group

RESOURCES