Conformational changes induced in the eukaryotic translation initiation factor eIF4E by a clinically relevant inhibitor, ribavirin triphosphate.
Conformational changes induced in the eukaryotic translation initiation factor eIF4E by a clinically relevant inhibitor, ribavirin triphosphate.
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DOI：
10.1016/j.bbrc.2013.03.125
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发表时间：
2013-05-10
影响因子：
3.1
通讯作者：
Borden, Katherine L. B.
中科院分区：
文献类型：
--
作者：
Volpon, Laurent;Osborne, Michael J.;Zahreddine, Hiba;Romeo, Andrea A.;Borden, Katherine L. B.
真核翻译起始因子eIF 4 E在包括急性髓性白血病（AML）在内的人类癌症中高度升高。一种潜在的抗癌药物利巴韦林靶向AML患者中的eIF 4 E活性，对应于临床应答。迄今为止，利巴韦林是唯一进入临床试验的eIF 4 E直接抑制剂。我们发现，利巴韦林作为竞争性抑制剂的甲基7-鸟苷（m7 G）帽，天然配体的eIF 4 E。在这里，我们研究了结合利巴韦林的活性代谢产物三磷酸利巴韦林（RTP）后，人eIF 4 E中发生的构象变化。我们的NMR数据揭示了对eIF 4 E的RTP亲和力的意外浓度依赖性。我们观察到在低微摩尔浓度（2-5μM eIF 4 E）下紧密结合的NMR光谱特征，但在更典型的NMR浓度（50-200μM）下亲和力弱得多。化学位移扰动和谱线增宽的比较表明，两种eIF 4 E-RTP复合物在帽结合口袋内RTP的精确定位方面不同，高亲和力复合物显示出对eIF 4 E的中心β-折叠和背表面的更广泛的变化，类似于m7 G帽。由于eIF 4 E和RTP的浓度依赖性聚集，高亲和力复合物和低亲和力复合物之间的差异出现。考虑到eIF 4 E和RTP的细胞内浓度以及对W56 A eIF 4 E突变体的差异结合，高亲和力复合物是最具生理相关性的。总之，这些研究结果表明，RTP结合在帽结合位点，但也提出了新的特点，这个口袋，应该考虑在药物设计的努力，并揭示新的见解配体eIF 4 E识别。
The eukaryotic translation initiation factor eIF4E is highly elevated in human cancers including acute myeloid leukemia (AML). A potential anticancer agent, ribavirin, targets eIF4E activity in AML patients corresponding to clinical responses. To date, ribavirin is the only direct inhibitor of eIF4E to reach clinical trials. We showed that ribavirin acts as a competitive inhibitor of the methyl 7-guanosine (m7G) cap, the natural ligand of eIF4E. Here we examine the conformational changes occurring in human eIF4E upon binding the active metabolite of ribavirin, ribavirin triphosphate (RTP). Our NMR data revealed an unexpected concentration dependence on RTP affinity for eIF4E. We observed NMR spectra characteristic of tight binding at low micromolar concentrations (2-5μM eIF4E) but much weaker affinity at more typical NMR concentrations (50-200μM). Comparison of chemical shift perturbation and line broadening suggest that the two eIF4E-RTP complexes differ in the precise positioning of RTP within the cap binding pocket, with the high affinity complex showing more extensive changes to the central β-sheet and dorsal surface of eIF4E, similar to m7G cap. The differences between high and low affinity complexes arise due to concentration dependent aggregation of eIF4E and RTP. Given the intracellular concentrations of eIF4E and RTP and the differential binding toward the W56A eIF4E mutant the high affinity complex is the most physiologically relevant. In summary, these findings demonstrate that RTP binds in the cap-binding site but also suggests new features of this pocket that should be considered in both drug design efforts and reveal new insights into ligand eIF4E recognition.
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影响因子：
11.4
作者：
Cohen, N;Sharma, M;Borden, KLB
通讯作者：
Borden, KLB
影响因子：
11.4
作者：
Ptushkina, M;von der Haar, T;McCarthy, JEG
通讯作者：
McCarthy, JEG
DOI：
10.1016/j.bbapap.2005.07.023
发表时间：
2005-12-01
影响因子：
3.2
作者：
Tomoo, K;Matsushita, Y;Ishida, T
通讯作者：
Ishida, T
影响因子：
5.6
作者：
Brown, Christopher J.;McNae, Iain;Walkinshaw, Malcolm D.
通讯作者：
Walkinshaw, Malcolm D.
影响因子：
11.4
作者：
Ptushkina, M;von der Haar, T;McCarthy, JEG
通讯作者：
McCarthy, JEG