Structures of the human dopamine D3 receptor-Gi complexes

•Structures of dopamine receptor D3R with agonists pramipexole and PD128907•Different binding modes similar pharmacological properties to D3R•Conformational changes associated activation selective G protein coupling•Selective mechanism versus D2R D4R The system, including five receptors (D1R–D5R), plays essential roles in the central nervous system (CNS), ligands that activate have been used treat many neuropsychiatric disorders. Here, we report two cryo-EM structures human complex an inhibitory bound D3R-selective PD128907 pramipexole, latter which is patients Parkinson’s disease. reveal agonist distinct from antagonist-bound structure conformational signatures for ligand-induced activation. Mutagenesis homology modeling illuminate determinants ligand specificity across mechanisms Gi coupling. Collectively our work reveals basis provides structural templates designing specific CNS diseases targeting dopaminergic system. Dopamine one most important neurotransmitters (CNS). 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For both complexes, contain residues positions 32 400 missing (residues 223–321) long intracellular loop 3 (ICL3). majority side chains seven transmembrane helical domains (TMDs) can be clearly defined 1; Interestingly, cholesterol found around TMD bundle, consistent fact (D2R, D4R) date do not any molecule Scholar).Figure 2Molecular recognition D3RShow caption(A B) Cryo-EM ligand-binding pocket pramipexole- structures.(C) Detailed interaction between D3R.(D) Schematic representation pramipexole-binding interactions. Hydrogen bonds shown black dashed lines. Hydrophobic amino acids green.(E) Electrostatic potential map pocket.(F) D3R.(G) PD128907-binding interactions green.(H) pocket.See also S3 Tables S2 S3.View Large Image ViewerDownload Hi-res image Download (PPT) (A structures. (C) D3R. (D) green. (E) pocket. (F) (G) (H) See S3. overall each other, root-mean-square deviation (RMSD) 0.3 Å atoms 259 1C–1F). quality EM allowed unambiguous top half 1C–1F, 2B). composed (TM) helices extracellular loops (ECLs) 1G 1H). elliptically shaped entry open area approximate 10 × 28 (the distance C? E902.65 S3667.36 Y321.35 V1895.39; Figures Both docked into bottom orthosteric 2C 2F), axes running TM5 TM7 biogenic amine group located same spatial position, forming charge highly conserved residue D1103.32 2D 2G). electrostatic generally negative, would fit positive 2E 2H). pocket, overlap extensively exception N3 O3 hydroxyl 3). These groups ?3.3 apart, pointing down toward points up H3496.55 upper 3B–3D). subtle differences chemical resulted size shape pockets volumes 718 574 Å3, respectively, PD128907. molecular 165 198 occupy only 23% 34% stabilized hydrophobic polar illustrated 2G. Besides D1103.32, forms hydrogen chain T1153.37 2D), whereas different set S1925.42 2F To correlate observations activity, individually mutated alanine assessed expression levels ability using radioligand competition assay [3H]-methylspiperone 3E; S3; S3). show abolished when although reduced about WT receptor, underscoring critical function (Table various degrees made other (Tables interact NanoBiT assays Gi-binding activity promoted ?3-fold dopamine, PD12807, potencies 80 8 nM F3456.51 key sandwich primary reinforce N1 2). Mutations either or potency ?1,000-fold Mutation toggle switch residue, W3426.48, showed class (Lin Sakmar, 1996Lin Sakmar T.P. 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S1173.39, F3386.44, D752.50 corresponding site S4F S4G), lead extension volume S4H S4I), assembly primarily interfaces G?i subunit. first major interface last 15 C-terminal ?5 helix G?i, inserted gap TM3 TM5/6 cavity 5A–5D). second ICL2 packed against cleft ?N helix, ?-turns G?-Ras domain, (termed ?N-?5 cleft; 5C 5D). amphipathic (I344, L348, C351, L353, F354) patch (TM3: V1323.54; TM5: I2115.61, L2155.65, R2185.68, R2225.72; TM6: R3236.29, K3266.32, A3276.33, M3306.36, V3316.37). mediates V136 Y138ICL2 along pattern largely 5E). Beside interactions, G?i. displays charges ends TM3/5/6/7 5E 5F). Correspondingly, domain negatively charged charge-complementary 5H). Importantly, adenosine A1 (A1R) (Draper-Joyce 2018Draper-Joyce C.J. Khoshouei Thal Liang Y.L. Nguyen A.T.N. Venugopal Plitzko Danev al.Structure adenosine-bound receptor-Gi complex.Nature. 558: 559-563Crossref (213) cannabinoid 1 (CB1) (Kumar 2019Kumar K.K. Shalev-Benami Robertson Banister S.D. Hollingsworth S.A. 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