Thermodynamics of mRNA 5' cap binding by eukaryotic translation initiation factor eIF4E.
Thermodynamics of mRNA 5' cap binding by eukaryotic translation initiation factor eIF4E.
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真核翻译起始因子 eIF4E 结合 mRNA 5 帽的热力学。
DOI：
10.1021/bi0491651
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Stolarski,Ryszard
中科院分区：
文献类型：
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作者：
Niedzwiecka,Anna;Darzynkiewicz,Edward;Stolarski,Ryszard
真核生物中mRNA的翻译始于高度保守的蛋白eIF4E对5 '帽结构的特异性识别。用发射光谱法研究了eIF4E与9种化学帽类似物相互作用的热力学。高灵敏度测量帽结合时的内在蛋白质荧光猝灭提供了279至314 K温度范围内的平衡关联常数。van't Hoff分析结果表明，在293 K下，整个帽类化合物的结合焓为负，为−16.6 ~−81 kJ mol-1，熵范围为+40.3 ~−136 jmol - 1k -1。主要的焓贡献来自磷酸链和带正电的氨基酸的相互作用以及7-甲基鸟嘌呤与色氨酸的阳离子- π堆积。等温焓-熵补偿（Tc= 399±24 K）具有重要的统计学意义，表明apo- eif4e有显著波动，表明帽结合微态比所有构象态的平均能量低9.66±1.7 kJ mol-1。对于五个帽类似物，已经发现了大而正的热容变化。ΔCp°的值与eIF4E结合的自由能相关，这是由于蛋白质在与帽类似物相互作用时变硬。在生物温度下，天然帽的结合具有有利的焓和熵。帽- eif4e结合与二核苷酸帽类似物分子内自堆积的热力学耦合强烈影响结合的焓和熵，但对所得ΔG°和ΔCp°值的影响可以忽略不计。
Translation of mRNA in eukaryotes begins with specific recognition of the 5‘ cap structure by the highly conserved protein, eIF4E. The thermodynamics of eIF4E interaction with nine chemical cap analogues has been studied by means of emission spectroscopy. High-sensitivity measurements of intrinsic protein fluorescence quenching upon cap binding provided equilibrium association constants in the temperature range of 279 to 314 K. A van't Hoff analysis yielded the negative binding enthalpies for the entire cap analogue series, −16.6 to −81 kJ mol-1, and the entropies covering the range of +40.3 to −136 J mol-1K-1at 293 K. The main enthalpic contributions come from interactions of the phosphate chains and positively charged amino acids and the cation−π stacking of 7-methylguanine with tryptophans. A nontrivial, statistically important isothermal enthalpy−entropy compensation has been detected (Tc= 399 ± 24 K), which points to significant fluctuations ofapo-eIF4E and indicates that the cap-binding microstate lies 9.66 ± 1.7 kJ mol-1below the mean energy of all available conformational states. For five cap analogues, large and positive heat capacity changes have been found. The values of ΔCp° correlate with the free energies of eIF4E binding due to stiffening of the protein upon interaction with cap analogues. At biological temperatures, binding of the natural caps has both favorable enthalpy and favorable entropy. Thermodynamic coupling of cap-eIF4E association to intramolecular self-stacking of dinucleotide cap analogues strongly influences the enthalpies and entropies of the binding, but has a negligible effect on the resultant ΔG° and ΔCp° values.