Discovery Technology, Hoffmann-La Roche Inc., 340 Kingsland Street, Nutley, NJ 07110, USA.
Anal Biochem. 2013 Mar 1;434(1):166-71. doi: 10.1016/j.ab.2012.11.020. Epub 2012 Dec 5.
The eukaryotic initiation factor 4E (eIF4E) is the key component of the translational initiation complex that recruits mRNA by binding to a unique "cap" structure located at the 5' end of the mRNA. Overexpression of eIF4E has been implicated in the development of cancer, potentially as a result of increasing the cellular levels of proteins involved in processes that include proliferation and regulation of apoptosis. As a result, the cap-binding site of eIF4E has become a target for the development of anti-cancer therapeutics. The structure of eIF4E bound to the cap mimic 7-methyl-GDP revealed that two tryptophans from different loops in eIF4E sandwiched the 7-methylguanine group between them. This interaction gives rise to a strong exciton coupling signal between the two tryptophans that can be visualized by CD spectroscopy. eIF4E is a challenging protein to work with because of a propensity to aggregate under conditions used in biophysical techniques. CD spectroscopy provides a gentle, solution-based approach to study binding to the cap-binding site of eIF4E. Evidence is provided that the exciton coupling signal can be used to both qualitatively and quantitatively analyze the binding of cap analogs to eIF4E.
真核起始因子 4E（eIF4E）是翻译起始复合物的关键组成部分，通过与 mRNA 5' 端独特的“帽”结构结合来招募 mRNA。eIF4E 的过表达与癌症的发展有关，可能是由于参与包括增殖和细胞凋亡调节在内的过程的蛋白质的细胞水平增加所致。因此，eIF4E 的帽结合位点已成为开发抗癌治疗药物的目标。与帽类似物 7-甲基-GDP 结合的 eIF4E 结构表明，eIF4E 中两个来自不同环的色氨酸将 7-甲基鸟嘌呤基团夹在它们之间。这种相互作用在两个色氨酸之间产生了一个强的激子耦合信号，可以通过 CD 光谱学可视化。由于在生物物理技术中使用的条件下易于聚集，因此 eIF4E 是一种具有挑战性的蛋白质。CD 光谱学提供了一种温和的基于溶液的方法来研究与 eIF4E 的帽结合位点的结合。有证据表明，激子耦合信号可用于定性和定量分析帽类似物与 eIF4E 的结合。
