1l8b
From Proteopedia
(New page: 200px<br /><applet load="1l8b" size="450" color="white" frame="true" align="right" spinBox="true" caption="1l8b, resolution 1.8Å" /> '''Cocrystal Structure o...) |
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| - | [[Image:1l8b.jpg|left|200px]]<br /><applet load="1l8b" size=" | + | [[Image:1l8b.jpg|left|200px]]<br /><applet load="1l8b" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1l8b, resolution 1.8Å" /> | caption="1l8b, resolution 1.8Å" /> | ||
'''Cocrystal Structure of the Messenger RNA 5' Cap-binding Protein (eIF4E) bound to 7-methylGpppG'''<br /> | '''Cocrystal Structure of the Messenger RNA 5' Cap-binding Protein (eIF4E) bound to 7-methylGpppG'''<br /> | ||
==Overview== | ==Overview== | ||
| - | mRNA 5'-cap recognition by the eukaryotic translation initiation factor | + | mRNA 5'-cap recognition by the eukaryotic translation initiation factor eIF4E has been exhaustively characterized with the aid of a novel fluorometric, time-synchronized titration method, and X-ray crystallography. The association constant values of recombinant eIF4E for 20 different cap analogues cover six orders of magnitude; with the highest affinity observed for m(7)GTP (approximately 1.1 x 10(8) M(-1)). The affinity of the cap analogues for eIF4E correlates with their ability to inhibit in vitro translation. The association constants yield contributions of non-covalent interactions involving single structural elements of the cap to the free energy of binding, giving a reliable starting point to rational drug design. The free energy of 7-methylguanine stacking and hydrogen bonding (-4.9 kcal/mol) is separate from the energies of phosphate chain interactions (-3.0, -1.9, -0.9 kcal/mol for alpha, beta, gamma phosphates, respectively), supporting two-step mechanism of the binding. The negatively charged phosphate groups of the cap act as a molecular anchor, enabling further formation of the intermolecular contacts within the cap-binding slot. Stabilization of the stacked Trp102/m(7)G/Trp56 configuration is a precondition to form three hydrogen bonds with Glu103 and Trp102. Electrostatically steered eIF4E-cap association is accompanied by additional hydration of the complex by approximately 65 water molecules, and by ionic equilibria shift. Temperature dependence reveals the enthalpy-driven and entropy-opposed character of the m(7)GTP-eIF4E binding, which results from dominant charge-related interactions (DeltaH degrees =-17.8 kcal/mol, DeltaS degrees= -23.6 cal/mol K). For recruitment of synthetic eIF4GI, eIF4GII, and 4E-BP1 peptides to eIF4E, all the association constants were approximately 10(7) M(-1), in decreasing order: eIF4GI>4E-BP1>eIF4GII approximately 4E-BP1(P-Ser65) approximately 4E-BP1(P-Ser65/Thr70). Phosphorylation of 4E-BP1 at Ser65 and Thr70 is insufficient to prevent binding to eIF4E. Enhancement of the eIF4E affinity for cap occurs after binding to eIF4G peptides. |
==About this Structure== | ==About this Structure== | ||
| - | 1L8B is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with MGP as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1L8B is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with <scene name='pdbligand=MGP:'>MGP</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1L8B OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Dadlez, M.]] | [[Category: Dadlez, M.]] | ||
[[Category: Darzynkiewicz, E.]] | [[Category: Darzynkiewicz, E.]] | ||
| - | [[Category: Gingras, A | + | [[Category: Gingras, A C.]] |
[[Category: Jankowska-Anyszka, M.]] | [[Category: Jankowska-Anyszka, M.]] | ||
[[Category: Mak, P.]] | [[Category: Mak, P.]] | ||
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[[Category: eukaryotic initiation factor 4e]] | [[Category: eukaryotic initiation factor 4e]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:42:24 2008'' |
Revision as of 11:42, 21 February 2008
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Cocrystal Structure of the Messenger RNA 5' Cap-binding Protein (eIF4E) bound to 7-methylGpppG
Overview
mRNA 5'-cap recognition by the eukaryotic translation initiation factor eIF4E has been exhaustively characterized with the aid of a novel fluorometric, time-synchronized titration method, and X-ray crystallography. The association constant values of recombinant eIF4E for 20 different cap analogues cover six orders of magnitude; with the highest affinity observed for m(7)GTP (approximately 1.1 x 10(8) M(-1)). The affinity of the cap analogues for eIF4E correlates with their ability to inhibit in vitro translation. The association constants yield contributions of non-covalent interactions involving single structural elements of the cap to the free energy of binding, giving a reliable starting point to rational drug design. The free energy of 7-methylguanine stacking and hydrogen bonding (-4.9 kcal/mol) is separate from the energies of phosphate chain interactions (-3.0, -1.9, -0.9 kcal/mol for alpha, beta, gamma phosphates, respectively), supporting two-step mechanism of the binding. The negatively charged phosphate groups of the cap act as a molecular anchor, enabling further formation of the intermolecular contacts within the cap-binding slot. Stabilization of the stacked Trp102/m(7)G/Trp56 configuration is a precondition to form three hydrogen bonds with Glu103 and Trp102. Electrostatically steered eIF4E-cap association is accompanied by additional hydration of the complex by approximately 65 water molecules, and by ionic equilibria shift. Temperature dependence reveals the enthalpy-driven and entropy-opposed character of the m(7)GTP-eIF4E binding, which results from dominant charge-related interactions (DeltaH degrees =-17.8 kcal/mol, DeltaS degrees= -23.6 cal/mol K). For recruitment of synthetic eIF4GI, eIF4GII, and 4E-BP1 peptides to eIF4E, all the association constants were approximately 10(7) M(-1), in decreasing order: eIF4GI>4E-BP1>eIF4GII approximately 4E-BP1(P-Ser65) approximately 4E-BP1(P-Ser65/Thr70). Phosphorylation of 4E-BP1 at Ser65 and Thr70 is insufficient to prevent binding to eIF4E. Enhancement of the eIF4E affinity for cap occurs after binding to eIF4G peptides.
About this Structure
1L8B is a Single protein structure of sequence from Mus musculus with as ligand. Full crystallographic information is available from OCA.
Reference
Biophysical studies of eIF4E cap-binding protein: recognition of mRNA 5' cap structure and synthetic fragments of eIF4G and 4E-BP1 proteins., Niedzwiecka A, Marcotrigiano J, Stepinski J, Jankowska-Anyszka M, Wyslouch-Cieszynska A, Dadlez M, Gingras AC, Mak P, Darzynkiewicz E, Sonenberg N, Burley SK, Stolarski R, J Mol Biol. 2002 Jun 7;319(3):615-35. PMID:12054859
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