Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China.
Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, School of Pharmacy, Chengdu University, Chengdu 610106, China.
J Chem Inf Model. 2023 Sep 25;63(18):5847-5862. doi: 10.1021/acs.jcim.3c00672. Epub 2023 Aug 31.
Within over 800 members of G-protein-coupled receptors, there are numerous orphan receptors whose endogenous ligands are largely unknown, providing many opportunities for novel drug discovery. However, the lack of an in-depth understanding of the intrinsic working mechanism for orphan receptors severely limits the related rational drug design. The G-protein-coupled receptor 52 (GPR52) is a unique orphan receptor that constitutively increases cellular 5'-cyclic adenosine monophosphate (cAMP) levels without binding any exogenous agonists and has been identified as a promising therapeutic target for central nervous system disorders. Although recent structural biology studies have provided snapshots of both active and inactive states of GPR52, the mechanism of the conformational transition between these states remains unclear. Here, an acceptable self-activation pathway for GPR52 was proposed through 6 μs Gaussian accelerated molecular dynamics (GaMD) simulations, in which the receptor spontaneously transitions from the active state to that matching the inactive crystal structure. According to the three intermediate states of the receptor obtained by constructing a reweighted potential of mean force, how the allosteric regulation occurs between the extracellular orthosteric binding pocket and the intracellular G-protein-binding site is revealed. Combined with the independent gradient model, several important microswitch residues and the allosteric communication pathway that directly links the two regions are both identified. Transfer entropy calculations not only reveal the complex allosteric signaling within GPR52 but also confirm the unique role of ECL2 in allosteric regulation, which is mutually validated with the results of GaMD simulations. Overall, this work elucidates the allosteric mechanism of GPR52 at the atomic level, providing the most detailed information to date on the self-activation of the orphan receptor.
在超过 800 种 G 蛋白偶联受体中，存在许多孤儿受体，其内源性配体在很大程度上尚不清楚，这为新药发现提供了许多机会。然而，对孤儿受体内在工作机制缺乏深入了解严重限制了相关的合理药物设计。G 蛋白偶联受体 52（GPR52）是一种独特的孤儿受体，它在不结合任何外源性激动剂的情况下持续增加细胞 5' - 环磷酸腺苷（cAMP）水平，已被确定为治疗中枢神经系统疾病的有前途的治疗靶点。尽管最近的结构生物学研究提供了 GPR52 的活性和非活性状态的快照，但这些状态之间构象转变的机制仍不清楚。在这里，通过 6 μs 高斯加速分子动力学（GaMD）模拟提出了一种可接受的 GPR52 自激活途径，其中受体自发地从活性状态转变为与非活性晶体结构匹配的状态。根据通过构建重加权平均力势能获得的受体的三个中间状态，揭示了细胞外正位结合口袋和细胞内 G 蛋白结合位点之间的变构调节如何发生。结合独立梯度模型，确定了几个重要的微切换残基和直接连接两个区域的变构通讯途径。传递熵计算不仅揭示了 GPR52 内复杂的变构信号，还证实了 ECL2 在变构调节中的独特作用，这与 GaMD 模拟的结果相互验证。总的来说，这项工作在原子水平上阐明了 GPR52 的变构机制，为孤儿受体的自激活提供了迄今为止最详细的信息。
