Che Kateryna, Muttenthaler Markus, Kurzbach Dennis
University Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Str. 38, A-1090 Vienna, Austria.
The University of Queensland, Institute for Molecular Bioscience, 306 Carmody Rd, 4072 St Lucia, Brisbane, Queensland, Australia.
Comput Struct Biotechnol J. 2021 Oct 18;19:5826-5833. doi: 10.1016/j.csbj.2021.10.024. eCollection 2021.
The neuropeptide vasopressin (VP) and its three G protein-coupled receptors (VR, VR and VR) are of high interest in a wide array of drug discovery programs. VR is of particular importance due to its cardiovascular functions and diverse roles in the central nervous system. The structure-activity relationships underpinning ligand-receptor interactions remain however largely unclear, hindering rational drug design. This is not least due to the high structural flexibility of VP in its free as well as receptor-bound states. In this work, we developed a novel approach to reveal features of conformational selectivity upon VP-VR complex formation. We employed virtual screening strategies to probe VP's conformational space for transiently adopted structures that favor binding to VR. To this end, we dissected the VP conformational space into three sub-ensembles, each containing distinct structural sets for VP's three-residue C-terminal tail. We validated the computational results with experimental nuclear magnetic resonance (NMR) data and docked each sub-ensemble to VR. We observed that the conformation of VP's three-residue tail significantly modulated the complex dissociation constants. Solvent-exposed and proline -configured VP tail conformations bound to the receptor with three-fold enhanced affinities compared to compacted or -configured conformations. The solvent-exposed and more flexible structures facilitated unique interaction patterns between VP and VR transmembrane helices 3, 4, and 6 which led to high binding energies. The presented "virtual conformational space screening" approach, integrated with NMR spectroscopy, thus enabled identification and characterization of a conformational selection-type complex formation mechanism that confers novel perspectives on targeting the VP-VR interactions at the level of the encounter complex - an aspect that opens novel research avenues for understanding the functionality of the evolutionary selected conformational properties of VP, as well as guidance for ligand design strategies to provide more potent and selective VP analogues.
神经肽血管加压素（VP）及其三种G蛋白偶联受体（VR1、VR2和VR3）在众多药物发现项目中备受关注。由于其心血管功能以及在中枢神经系统中的多种作用，VR1尤为重要。然而，支撑配体 - 受体相互作用的构效关系在很大程度上仍不明确，这阻碍了合理的药物设计。这尤其归因于VP在其游离状态以及与受体结合状态下具有高度的结构灵活性。在这项工作中，我们开发了一种新方法来揭示VP - VR1复合物形成时的构象选择性特征。我们采用虚拟筛选策略来探索VP的构象空间，以寻找有利于与VR1结合的瞬时采用结构。为此，我们将VP构象空间分解为三个子集合，每个子集合包含VP三残基C末端尾巴的不同结构集。我们用实验核磁共振（NMR）数据验证了计算结果，并将每个子集合对接至VR1。我们观察到VP三残基尾巴的构象显著调节了复合物的解离常数。与紧密或脯氨酸构型的构象相比，溶剂暴露且脯氨酸构型的VP尾巴构象与受体结合时亲和力提高了三倍。溶剂暴露且更灵活的结构促进了VP与VR1跨膜螺旋3、4和6之间独特的相互作用模式，从而导致高结合能。因此，所提出的“虚拟构象空间筛选”方法与NMR光谱相结合，能够识别和表征一种构象选择型复合物形成机制，该机制为在相遇复合物水平上靶向VP - VR1相互作用提供了新的视角——这一方面为理解VP进化选择的构象特性的功能开辟了新的研究途径，也为配体设计策略提供了指导，以提供更有效和选择性更强的VP类似物。
