Wang Fangfang, Wang Yang, Qiu Weicheng, Zhang Qiansen, Yang Huaiyu, Song Gaojie
Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China.
Center of Biomedical Physics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325000, China; Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou, Zhejiang 325001, China.
J Mol Biol. 2023 Mar 15;435(6):167979. doi: 10.1016/j.jmb.2023.167979. Epub 2023 Jan 28.
Adhesion G protein-coupled receptors (aGPCRs) play a pivotal role in human immune responses, cellular communication, organ development, and other processes. GPR110 belongs to the aGPCR subfamily VI and was initially identified as an oncogene involved in lung and prostate cancers. GPR110 contains tandem adhesion domains at the extracellular region that mediate inter-cellular signaling. However, the structural organization and signaling mechanism for these tandem domains remain unclear. Here, we report the crystal structure of a GPR110 fragment composing the SEA, HormR, and GAIN domains at 2.9 Å resolution. The structure together with MD simulations reveal rigid connections between these domains that are stabilized by complementary interfaces. Strikingly, we found N-linked carbohydrates attached to N389 of the GAIN domain form extensive contacts with the preceding HormR domain. These interactions appear to be critical for folding, as removal of the glycosylation site greatly decreases expression of the GPR110 extracellular fragment. We further demonstrate that the ligand synaptamide fits well within the hydrophobic pocket occupied by the Stachel peptide in the rest state. This suggests that the agonist may function by removing the Stachel peptide which in turn redocks to the orthosteric pocket for receptor activation. Taken together, our structural findings and analyses provide novel insights into the activation mechanism for aGPCRs.
粘附G蛋白偶联受体（aGPCRs）在人类免疫反应、细胞通讯、器官发育及其他过程中发挥着关键作用。GPR110属于aGPCR VI亚家族，最初被鉴定为一种参与肺癌和前列腺癌的癌基因。GPR110在细胞外区域含有串联粘附结构域，介导细胞间信号传导。然而，这些串联结构域的结构组织和信号传导机制仍不清楚。在此，我们报告了一个由SEA、HormR和GAIN结构域组成的GPR110片段在2.9 Å分辨率下的晶体结构。该结构与分子动力学模拟一起揭示了这些结构域之间由互补界面稳定的刚性连接。令人惊讶的是，我们发现连接到GAIN结构域N389的N-连接碳水化合物与前面的HormR结构域形成广泛接触。这些相互作用似乎对折叠至关重要，因为去除糖基化位点会大大降低GPR110细胞外片段的表达。我们进一步证明，配体突触酰胺在静息状态下很好地契合由Stachel肽占据的疏水口袋。这表明激动剂可能通过去除Stachel肽起作用，而Stachel肽反过来重新对接至正构口袋以激活受体。综上所述，我们的结构发现和分析为aGPCRs的激活机制提供了新的见解。
