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Allosteric coupling between G‐protein binding and extracellular ligand binding sites in GPR52 revealed by 19F‐NMR and cryo‐electron microscopy

Year: 2023

Type: article

Abstract: Allosteric coupling between G-protein binding and extracellular ligand binding sites in GPR52 revealed by 19 F-NMR and cryo-electron microscopyDear Editor, GPR52 is a class-A orphan GPCR, which has been reported as a target for treating Huntington's disease, cognitive impairment, schizophrenia, and neuromuscular disorders.Previous structure determinations showed that GPR52 adopts an active conformation when bound to G-protein in the absence of any ligand.1 A self-activation model was proposed, attributed to a built-in agonist motif embedded in the extracellular loop 2 (ECL2) near the orthosteric ligand binding pocket; this would also explain the high basal activity of GPR52.The synthetic ligand c17 is bound to a GPR52 side pocket, as shown in the co-crystal structure.1 Recently, some new molecules with a similar chemical structure to c17 have entered pre-clinical trials for GPR52-related disorders.2 Structural and conformational dynamics studies of GPCRs are crucial for the screening of new ligands and understanding the molecular mechanisms of previously untapped drug targets.Here, we show a new cryo-electron microscopy (cryo-EM) structure of GPR52 bound with c17 at the extracellular side and G-protein at the intracellular side.19 F-NMR studies 3 of the complex by observation of the trifluoromethyl group in c17 (Figure 1A) revealed local polymorphisms in GPR52.19 F-NMR data also indicate localized differences in the extracellular ligand binding pocket between the GPR52-c17 complex and the ternary complex with the G-protein.To investigate the dynamics of the ligand binding pocket of GPR52, the near-wild type receptor and some variants were expressed in Sf9 insect cells (Figure S1).The -CF 3 group of c17 (Figure 1A) serves here as a natural 19 F-NMR probe for studies of the complex with GPR52.For NMR measurements, the GPR52 complexes were reconstituted in lauryl maltose neopentyl glycol/cholesteryl hemisuccinate tris salt mixed micelles.1D 19 F-NMR spectra of the ligand c17 in the free state as well as bound to GPR52* (see Table S1 for the

Source: MedComm

DOI: 10.1002/mco2.260