Improved eIF4E Binding Peptides by Phage Display Guided Design: Plasticity of Interacting Surfaces Yield Collective Effects
Improved eIF4E Binding Peptides by Phage Display Guided Design: Plasticity of Interacting Surfaces Yield Collective Effects
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DOI：
10.1371/journal.pone.0047235
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发表时间：
2012-10-19
期刊：
影响因子：
3.7
通讯作者：
Brown, Christopher J.
中科院分区：
文献类型：
--
作者：
Zhou, Weizhuang;Quah, Soo T.;Brown, Christopher J.
真核起始因子（eIF）4 E在许多类型的癌症中过表达，如乳腺癌、头颈癌和肺癌。eIF 4 E水平增加的结果是促肿瘤发生蛋白（例如c-Myc和血管内皮生长因子）的优先翻译，因此被视为潜在的治疗靶点。在这项工作中，一种新的噬菌体展示肽已被分离出的eIF 4 E。从噬菌体序列中描绘了两个氨基酸，当取代到eIF 4G 1序列中时，其改善了结合。这些取代都不参与与eIF 4 E的直接相互作用，而是通过优化螺旋加帽基序或限制肽的构象灵活性来发挥作用。相反，将剩余的噬菌体衍生的氨基酸取代到eIF 4G 1序列中破坏了肽与eIF 4 E的结合。有趣的是，当这些破坏性取代中的一些与来自噬菌体肽的关键突变组合时，它们导致亲和力的改善。原子计算机模拟显示，噬菌体和eIF 4G 1衍生肽序列在eIF 4 E上的相互作用位点有细微的不同。这就提出了一个问题，特别是在平面相互作用位点的背景下，如eIF 4 E所表现出的，即给定蛋白质表面的复杂可塑性，结构-活性关系的构建应该考虑到肽结合界面的空间定位中的显著运动的可能性，包括肽的显著的自由运动。
Eukaryotic initiation factor (eIF)4E is over-expressed in many types of cancer such as breast, head and neck, and lung. A consequence of increased levels of eIF4E is the preferential translation of pro-tumorigenic proteins (e.g. c-Myc and vascular endothelial growth factor) and as a result is regarded as a potential therapeutic target. In this work a novel phage display peptide has been isolated against eIF4E. From the phage sequence two amino acids were delineated which improved binding when substituted into the eIF4G1 sequence. Neither of these substitutions were involved in direct interactions with eIF4E and acted either via optimization of the helical capping motif or restricting the conformational flexibility of the peptide. In contrast, substitutions of the remaining phage derived amino acids into the eIF4G1 sequence disrupted binding of the peptide to eIF4E. Interestingly when some of these disruptive substitutions were combined with key mutations from the phage peptide, they lead to improved affinities. Atomistic computer simulations revealed that the phage and the eIF4G1 derivative peptide sequences differ subtly in their interaction sites on eIF4E. This raises the issue, especially in the context of planar interaction sites such as those exhibited by eIF4E, that given the intricate plasticity of protein surfaces, the construction of structure-activity relationships should account for the possibility of significant movement in the spatial positioning of the peptide binding interface, including significant librational motions of the peptide.