Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, 47405, USA.
ARC Centre for Cryo-electron Microscopy of Membrane Proteins and Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
Nat Commun. 2023 Jun 7;14(1):3328. doi: 10.1038/s41467-023-38894-8.
The neurotensin receptor 1 (NTS) is a G protein-coupled receptor (GPCR) with promise as a drug target for the treatment of pain, schizophrenia, obesity, addiction, and various cancers. A detailed picture of the NTS structural landscape has been established by X-ray crystallography and cryo-EM and yet, the molecular determinants for why a receptor couples to G protein versus arrestin transducers remain poorly defined. We used CH-methionine NMR spectroscopy to show that binding of phosphatidylinositol-4,5-bisphosphate (PIP2) to the receptor's intracellular surface allosterically tunes the timescale of motions at the orthosteric pocket and conserved activation motifs - without dramatically altering the structural ensemble. β-arrestin-1 further remodels the receptor ensemble by reducing conformational exchange kinetics for a subset of resonances, whereas G protein coupling has little to no effect on exchange rates. A β-arrestin biased allosteric modulator transforms the NTS:G protein complex into a concatenation of substates, without triggering transducer dissociation, suggesting that it may function by stabilizing signaling incompetent G protein conformations such as the non-canonical state. Together, our work demonstrates the importance of kinetic information to a complete picture of the GPCR activation landscape.
神经降压素受体 1（NTS）是一种 G 蛋白偶联受体（GPCR），有望成为治疗疼痛、精神分裂症、肥胖、成瘾和各种癌症的药物靶点。X 射线晶体学和 cryo-EM 已经建立了 NTS 结构景观的详细图片，但对于为什么受体与 G 蛋白或阻滞蛋白转导器偶联的分子决定因素仍定义不明确。我们使用 CH-甲硫氨酸 NMR 光谱法表明，磷脂酰肌醇-4,5-二磷酸（PIP2）与受体的细胞内表面的结合在变构上调节了正位口袋和保守的激活基序的运动时间尺度 - 而不会显著改变结构整体。β-阻滞蛋白 1 通过降低一部分共振的构象交换动力学进一步重塑受体整体，而 G 蛋白偶联对交换率几乎没有影响。β-阻滞蛋白偏向变构调节剂将 NTS：G 蛋白复合物转化为一连串亚状态，而不会触发转导器解离，这表明它可能通过稳定信号无效的 G 蛋白构象（如非规范状态）发挥作用。总之，我们的工作表明，动力学信息对于完整的 GPCR 激活景观非常重要。
