Structural mechanism underlying primary and secondary coupling between GPCRs and the Gi/o family

• Published in: Nature communications 2020-06, Vol.11 (1), p.3160-12, Article 3160
• Main Authors: Kim, Hee Ryung, Xu, Jun, Maeda, Shoji, Duc, Nguyen Minh, Ahn, Donghoon, Du, Yang, Chung, Ka Young
• Format: Article
• Language: English
• Subjects: 101/58; 631/337; 631/45/535; 631/80/86; Acetylcholine receptors (muscarinic); Adrenergic receptors; Animals; Binding Sites; C-Terminus; Couplings; Deuterium; Exchanging; G protein-coupled receptors; GTP-Binding Proteins - chemistry; GTP-Binding Proteins - metabolism; Humanities and Social Sciences; Humans; Hydrogen-deuterium exchange; Hydrophobicity; Mass spectrometry; Mass spectroscopy; Molecular Structure; multidisciplinary; Mutagenesis; Proteins; Receptors; Receptors, Adrenergic, beta-2 - metabolism; Receptors, G-Protein-Coupled - chemistry; Receptors, G-Protein-Coupled - metabolism; Receptors, Muscarinic - metabolism; Residues; Science; Science (multidisciplinary); Scientific imaging; Signal Transduction - physiology; Spectroscopy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-16975-2

Heterotrimeric G proteins are categorized into four main families based on their function and sequence, Gs, Gi/o, Gq/11, and G12/13. One receptor can couple to more than one G protein subtype, and the coupling efficiency varies depending on the GPCR-G protein pair. However, the precise mechanism underlying different coupling efficiencies is unknown. Here, we study the structural mechanism underlying primary and secondary Gi/o coupling, using the muscarinic acetylcholine receptor type 2 (M2R) as the primary Gi/o-coupling receptor and the β 2 -adrenergic receptor (β 2 AR, which primarily couples to Gs) as the secondary Gi/o-coupling receptor. Hydrogen/deuterium exchange mass spectrometry and mutagenesis studies reveal that the engagement of the distal C-terminus of Gαi/o with the receptor differentiates primary and secondary Gi/o couplings. This study suggests that the conserved hydrophobic residue within the intracellular loop 2 of the receptor (residue 34.51) is not critical for primary Gi/o-coupling; however, it might be important for secondary Gi/o-coupling. G protein-coupled receptors (GPCRs) can couple to more than one G protein subtype, and the coupling efficiency varies depending on the GPCR-G protein pair. Here authors use hydrogen/deuterium exchange mass spectrometry and mutagenesis to study the structural mechanism underlying primary and secondary Gi/o coupling.