Sulfur-pi: a highly stabilizing binding motif in TNF receptors

描述（由申请人提供）：肿瘤坏死因子（TNF）超家族的成员，包括死亡受体和TNF受体，正在积极地作为癌症治疗和其他疾病的靶点。最近的细胞研究强调了死亡受体5中单个蛋氨酸残基（Met 152）的重要性，由此丙氨酸的突变完全破坏了配体结合。虽然还没有解释这种破坏，但我们对晶体结构的研究表明，DR5-Met152中的硫原子与TRAIL配体中的酪氨酸（Tyr237）非常接近（~ 5 A）。此外，表面等离子体共振测量表明，TRAIL-Tyr237突变为丙氨酸导致配体-受体解离常数增加五倍。对蛋白质数据库的搜索表明，蛋白质中硫和芳香基团之间相互作用的最佳几何形状，随后的量子化学计算表明，由于这种相互作用基序，具有显著的稳定性。尽管如此，在细胞生物学文献中很少（或没有）注意到这个潜在的重要基序。基于现有的晶体结构数据，我们最近发现在另一个TNF配体-受体对中存在类似的硫-芳香相互作用，即与TNF- r1结合的淋巴毒素α (LT1)。除了我们的观察和初步结果，目前还没有关于TNF- r1中这种相互作用的信息，也没有任何工作旨在理解TNF受体中硫-芳香基序的功能意义或化学基础。我们的假设是，硫原子在蛋氨酸和芳香残基之间的相互作用是TNF超家族配体-受体对中高度稳定和可靶向的结合基序的基础。该基金建议用实验分子和细胞生物学研究来补充我们的计算发现，以验证硫-芳香相互作用的生物学（和潜在的药学）重要性。

DESCRIPTION (provided by applicant): Members of the Tumor Necrosis Factor (TNF) superfamily, including the Death Receptors and TNF Receptors, are actively being pursued as targets for cancer therapy, among other diseases. Recent cellular studies highlight the importance of a single methionine residue (Met 152) within Death Receptor 5, whereby mutation to alanine completely disrupts ligand binding. While there is yet no explanation for this disruption, our interrogation of the crystal structure has revealed that the sulfur atom in DR5-Met152 is in close proximity (~ 5 A) to a tyrosine (Tyr237) in the TRAIL ligand. Additionally, Surface Plasmon Resonance measurements have shown that mutation of TRAIL-Tyr237 to alanine causes a five-fold increase in the ligand-receptor dissociation constant. A search of the protein data bank suggested an optimal geometry for the interaction between sulfur and aromatic groups in proteins, and subsequent quantum chemistry calculations have suggested significant stabilization due this interaction motif. Despite this, there has been little (or no) attention paid to this potentially important motif in the cell biology literature. Based upon available crystal structure data, we have recently discovered that a similar sulfur-aromatic interaction exists in another of the TNF ligand-receptor pairs, namely lymphotoxin-alpha (LT1) bound to TNF-R1. Other than our observations and preliminary results, no information yet exists regarding this interaction in TNF-R1, nor has any work been geared toward understanding the functional significance or the chemical foundations of the sulfur-aromatic motif in TNF receptors in general. It is our hypothesis that interactions between the sulfur atom in methionine and aromatic residues underlie a highly stabilizing and targetable binding motif within the ligand-receptor pairs of the TNF superfamily. This grant proposes to complement our computational findings with experimental molecular and cellular biology studies in order to validate the biological (and potential pharmaceutical) importance of the sulfur-aromatic interaction. PUBLIC HEALTH RELEVANCE: Tumor Necrosis Factor Superfamily proteins are involved in a wide range of diseases, including cancers and auto-immune diseases. This work will reveal new and critical chemical details about these proteins that can then be used for designing new treatments.