| Structural highlights
Function
[IF4E_HUMAN] Its translation stimulation activity is repressed by binding to the complex CYFIP1-FMR1 (By similarity). Recognizes and binds the 7-methylguanosine-containing mRNA cap during an early step in the initiation of protein synthesis and facilitates ribosome binding by inducing the unwinding of the mRNAs secondary structures. Component of the CYFIP1-EIF4E-FMR1 complex which binds to the mRNA cap and mediates translational repression. In the CYFIP1-EIF4E-FMR1 complex this subunit mediates the binding to the mRNA cap.[1] [4EBP1_HUMAN] Regulates eIF4E activity by preventing its assembly into the eIF4F complex. Mediates the regulation of protein translation by hormones, growth factors and other stimuli that signal through the MAP kinase and mTORC1 pathways.[2]
Publication Abstract from PubMed
The eukaryotic translation initiation factor eIF4E plays key roles in cap-dependent translation and mRNA export. These functions rely on binding the 7-methylguanosine moiety (5'cap) to the 5'-end of all mRNAs. eIF4E is regulated by proteins such as eIF4G and eIF4E binding proteins (4EBPs) that bind the dorsal surface of eIF4E, distal to the cap binding site, and modulate cap binding activity. Both proteins increase the affinity of eIF4E for 5'cap. Our understanding of the allosteric effects and structural underpinnings of 4EBP1 or eIF4G binding can be advanced by structural data on cap-free eIF4E bound to one of these proteins. Here, we report the crystal structure of apo-eIF4E and cap-free eIF4E in complex with a 4EBP1 peptide. We also monitored 4EBP1 binding to cap-free eIF4E in solution using NMR. Together, these studies suggest that 4EBP1 transforms eIF4E into a cap-receptive state. NMR methods were also used to compare the allosteric routes activated by 4EBP1, eIF4G, and the arenavirus Z protein, a negative regulator of cap binding. We observed chemical shift perturbation at the dorsal binding site leading to alterations in the core of the protein, which were ultimately communicated to the unoccupied cap binding site of eIF4E. There were notable similarities between the routes taken by 4EBP1 and eIF4G and differences from the negative regulator Z. Thus, binding of 4EBP1 or eIF4G allosterically drives alterations throughout the protein that increase the affinity of eIF4E for the 5'cap.
Structural Insights into the Allosteric Effects of 4EBP1 on the Eukaryotic Translation Initiation Factor eIF4E.,Siddiqui N, Tempel W, Nedyalkova L, Volpon L, Wernimont AK, Osborne MJ, Park HW, Borden KL J Mol Biol. 2011 Dec 9. PMID:22178476[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Tomoo K, Matsushita Y, Fujisaki H, Abiko F, Shen X, Taniguchi T, Miyagawa H, Kitamura K, Miura K, Ishida T. Structural basis for mRNA Cap-Binding regulation of eukaryotic initiation factor 4E by 4E-binding protein, studied by spectroscopic, X-ray crystal structural, and molecular dynamics simulation methods. Biochim Biophys Acta. 2005 Dec 1;1753(2):191-208. Epub 2005 Aug 24. PMID:16271312 doi:10.1016/j.bbapap.2005.07.023
- ↑ Pause A, Belsham GJ, Gingras AC, Donze O, Lin TA, Lawrence JC Jr, Sonenberg N. Insulin-dependent stimulation of protein synthesis by phosphorylation of a regulator of 5'-cap function. Nature. 1994 Oct 27;371(6500):762-7. PMID:7935836 doi:http://dx.doi.org/10.1038/371762a0
- ↑ Siddiqui N, Tempel W, Nedyalkova L, Volpon L, Wernimont AK, Osborne MJ, Park HW, Borden KL. Structural Insights into the Allosteric Effects of 4EBP1 on the Eukaryotic Translation Initiation Factor eIF4E. J Mol Biol. 2011 Dec 9. PMID:22178476 doi:10.1016/j.jmb.2011.12.002
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