Common activation mechanism of class A GPCRs

eLife - Tập 8
Qingtong Zhou1, Dehua Yang2,3,4, Meng Wu5,4,1, Yu Guo5,4,1, Wanjing Guo2,3,4, Zhong Li2,3,4, Xiaoqing Cai2,3, Antao Dai2,3, Wonjo Jang6, Eugene I. Shakhnovich7, Zhi‐Jie Liu5,1, Raymond C. Stevens5,1, Nevin A. Lambert6, M. Madan Babu8, Ming‐Wei Wang5,9,2,3,4, Suwen Zhao5,1
1iHuman Institute, ShanghaiTech University, Shanghai, China
2The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
3The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
4University of Chinese Academy of Sciences, Beijing, China
5School of Life Science and Technology, ShanghaiTech University, Shanghai, China
6Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, United States
7Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
8MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
9School of Pharmacy, Fudan University, Shanghai, China

Tóm tắt

Class A G-protein-coupled receptors (GPCRs) influence virtually every aspect of human physiology. Understanding receptor activation mechanism is critical for discovering novel therapeutics since about one-third of all marketed drugs target members of this family. GPCR activation is an allosteric process that couples agonist binding to G-protein recruitment, with the hallmark outward movement of transmembrane helix 6 (TM6). However, what leads to TM6 movement and the key residue level changes of this movement remain less well understood. Here, we report a framework to quantify conformational changes. By analyzing the conformational changes in 234 structures from 45 class A GPCRs, we discovered a common GPCR activation pathway comprising of 34 residue pairs and 35 residues. The pathway unifies previous findings into a common activation mechanism and strings together the scattered key motifs such as CWxP, DRY, Na+ pocket, NPxxY and PIF, thereby directly linking the bottom of ligand-binding pocket with G-protein coupling region. Site-directed mutagenesis experiments support this proposition and reveal that rational mutations of residues in this pathway can be used to obtain receptors that are constitutively active or inactive. The common activation pathway provides the mechanistic interpretation of constitutively activating, inactivating and disease mutations. As a module responsible for activation, the common pathway allows for decoupling of the evolution of the ligand binding site and G-protein-binding region. Such an architecture might have facilitated GPCRs to emerge as a highly successful family of proteins for signal transduction in nature.

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