Structure-based development of bitopic GPCR ligands showing functional selectivity at β-adrenergic receptors

G蛋白偶联受体（gpcr）是一种非常重要的药物靶点，有多个结合位点调节其功能。除了与天然激素/神经递质结合的正构位点和识别G蛋白或β-阻滞蛋白的细胞内位点外，还发现了位于细胞外前庭和受体面向膜侧的变构结合位点。双位配体是一种药物或先导化合物，它包含针对正构位的药效团和专门针对变构位的第二部分。本项目旨在基于对每个模块的结构和功能特性的理解以及它们的连接形成双功能实体的影响，设计、合成和生物学研究双配体。基于片段的虚拟筛选和化学合成产生的模块将被特别功能化和耦合，利用点击化学。我们将研究可扩散和共价结合的配体。计算化合物设计将基于心脏生理学中关键角色β-肾上腺素能受体（βAR）的高分辨率结构（x射线和低温电镜结构）。在对接、MD和FEP计算的指导下，我们将进化出与两个邻近受体位点（orthosteric binding pocket和细胞外前庭）具有最佳互补性和良好相互作用的双取向先导化合物。按照模块化的方法，我们将探索两个模块之间的协同或对立性质，赋予双色配体的个体药理学特征。基于对所选配体-受体复合物的结构和低温电镜结构的了解，新设计的双取向分子将优化其激活β2AR的能力，其Gi偏置优于Gs和β-阻滞蛋白。

G protein-coupled receptors (GPCRs) are highly important pharmaceutical targets with multiple binding sites modulating their function. Apart from the orthosteric site, binding the native hormone/ neurotransmitter and an intracellular site recognizing a G protein or β-arrestin, allosteric binding sites located at the extracellular vestibule and the membrane-facing side of the receptor have been identified. Bitopic ligands are drugs or lead compounds comprising a pharmacophore for the orthosteric site and a second moiety specifically addressing an allosteric site. This project aims to design, synthesize and biologically investigate bitopic GPCR ligands based on an understanding of the structural and functional properties of each module and the impact of their ligation forming a bifunctional entity. The modules resulting from fragment-based virtual screening and chemical synthesis will be specifically functionalized and coupled, taking advantage of click chemistry. We will work on diffusible and covalently binding ligands. The computational compound design will be based on high-resolution structures (X-ray and cryo-EM structures) for a key player in cardiac physiology, the β-adrenergic receptor (βAR). Guided by docking, MD and FEP calculations, we will evolve bitopic lead compounds showing optimal complementarity and favorable interactions with two proximate receptor sites, the orthosteric binding pocket and the extracellular vestibule. Following a modular approach, we will probe synergistic or opposing properties between the two modules conferring the individual pharmacological profile of the bitopic ligands. Based on a structural understanding and cryo-EM structures of selected ligand-receptor complexes, the newly designed bitopic molecules will be optimized for their ability to activate the β2AR with Gi bias over Gs and β-arrestin.