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Yi HB, Lee S, Seo K, Kim H, Kim M, Lee HS. Cellular and Biophysical Applications of Genetic Code Expansion. Chem Rev 2024; 124:7465-7530. [PMID: 38753805 DOI: 10.1021/acs.chemrev.4c00112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Despite their diverse functions, proteins are inherently constructed from a limited set of building blocks. These compositional constraints pose significant challenges to protein research and its practical applications. Strategically manipulating the cellular protein synthesis system to incorporate novel building blocks has emerged as a critical approach for overcoming these constraints in protein research and application. In the past two decades, the field of genetic code expansion (GCE) has achieved significant advancements, enabling the integration of numerous novel functionalities into proteins across a variety of organisms. This technological evolution has paved the way for the extensive application of genetic code expansion across multiple domains, including protein imaging, the introduction of probes for protein research, analysis of protein-protein interactions, spatiotemporal control of protein function, exploration of proteome changes induced by external stimuli, and the synthesis of proteins endowed with novel functions. In this comprehensive Review, we aim to provide an overview of cellular and biophysical applications that have employed GCE technology over the past two decades.
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Affiliation(s)
- Han Bin Yi
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Seungeun Lee
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Kyungdeok Seo
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Hyeongjo Kim
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Minah Kim
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Hyun Soo Lee
- Department of Chemistry, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
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2
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Harikumar KG, Piper SJ, Christopoulos A, Wootten D, Sexton PM, Miller LJ. Impact of secretin receptor homo-dimerization on natural ligand binding. Nat Commun 2024; 15:4390. [PMID: 38782989 PMCID: PMC11116414 DOI: 10.1038/s41467-024-48853-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 05/14/2024] [Indexed: 05/25/2024] Open
Abstract
Class B G protein-coupled receptors can form dimeric complexes important for high potency biological effects. Here, we apply pharmacological, biochemical, and biophysical techniques to cells and membranes expressing the prototypic secretin receptor (SecR) to gain insights into secretin binding to homo-dimeric and monomeric SecR. Spatial proximity between peptide and receptor residues, probed by disulfide bond formation, demonstrates that the secretin N-terminus moves from adjacent to extracellular loop 3 (ECL3) at wild type SecR toward ECL2 in non-dimerizing mutants. Analysis of fluorescent secretin analogs demonstrates stable engagement of the secretin C-terminal region within the receptor extracellular domain (ECD) for both dimeric and monomeric receptors, while the mid-region exhibits lower mobility while docked at the monomer. Moreover, decoupling of G protein interaction reduces mobility of the peptide mid-region at wild type receptor to levels similar to the mutant, whereas it has no further impact on the monomer. These data support a model of peptide engagement whereby the ability of SecR to dimerize promotes higher conformational dynamics of the peptide-bound receptor ECD and ECLs that likely facilitates more efficient G protein recruitment and activation, consistent with the higher observed functional potency of secretin at wild type SecR relative to the monomeric mutant receptor.
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Affiliation(s)
- Kaleeckal G Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, USA
| | - Sarah J Piper
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, USA.
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3
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Milburn JE, Harikumar KG, Piper SJ, Raval S, Christopoulos A, Wootten D, Sexton PM, Miller LJ. Secretin Amino-Terminal Structure-Activity Relationships and Complementary Mutagenesis at the Site of Docking to the Secretin Receptor. Mol Pharmacol 2022; 101:400-407. [PMID: 35351821 PMCID: PMC11033956 DOI: 10.1124/molpharm.122.000502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/22/2022] [Indexed: 04/24/2024] Open
Abstract
Class B1 G protein-coupled receptors are activated by peptides, with amino-terminal regions critical for biologic activity. Although high resolution structures exist, understanding of key features of the peptide activation domain that drive signaling is limited. In the secretin receptor (SecR) structure, interactions are observed between peptide residues His1 and Ser2 and seventh transmembrane segment (TM7) receptor residue E373. We interrogated these interactions using systematic structure-activity analysis of peptide and receptor. His1 was critical for binding and cAMP responses, but its orientation was not critical, and substitution could independently modify affinity and efficacy. Ser2 was also critical, with all substitutions reducing peptide affinity and functional responses proportionally. Mutation of E373 to conserved acidic Asp (E373D), uncharged polar Gln (E373Q), or charge-reversed basic Arg (E373R) did not alter receptor expression, with all exhibiting secretin-dependent cAMP accumulation. All position 373 mutants displayed reduced binding affinities and cAMP potencies for many peptide analogs, although relative effects of position 1 peptides were similar whereas position 2 peptides exhibited substantial differences. The peptide including basic Lys in position 2 was active at SecR having acidic Glu in position 373 and at E373D while exhibiting minimal activity at those receptors in which an acidic residue is absent in this position (E373Q and E373R). In contrast, the peptide including acidic Glu in position 2 was equipotent with secretin at E373R while being much less potent than secretin at wild-type SecR and E373D. These data support functional importance of a charge-charge interaction between the amino-terminal region of secretin and the top of TM7. SIGNIFICANCE STATEMENT: This work refines our molecular understanding of the activation mechanisms of class B1 G protein-coupled receptors. The amino-terminal region of secretin interacts with the seventh transmembrane segment of its receptor with structural specificity and with a charge-charge interaction helping to drive functional activation.
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Affiliation(s)
- Juliana E Milburn
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona (J.E.M., K.G.H., S.R., L.J.M.) and Drug Discovery Biology and Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia (S.J.P., A.C., D.W., P.M.S.)
| | - Kaleeckal G Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona (J.E.M., K.G.H., S.R., L.J.M.) and Drug Discovery Biology and Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia (S.J.P., A.C., D.W., P.M.S.)
| | - Sarah J Piper
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona (J.E.M., K.G.H., S.R., L.J.M.) and Drug Discovery Biology and Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia (S.J.P., A.C., D.W., P.M.S.)
| | - Sweta Raval
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona (J.E.M., K.G.H., S.R., L.J.M.) and Drug Discovery Biology and Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia (S.J.P., A.C., D.W., P.M.S.)
| | - Arthur Christopoulos
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona (J.E.M., K.G.H., S.R., L.J.M.) and Drug Discovery Biology and Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia (S.J.P., A.C., D.W., P.M.S.)
| | - Denise Wootten
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona (J.E.M., K.G.H., S.R., L.J.M.) and Drug Discovery Biology and Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia (S.J.P., A.C., D.W., P.M.S.)
| | - Patrick M Sexton
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona (J.E.M., K.G.H., S.R., L.J.M.) and Drug Discovery Biology and Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia (S.J.P., A.C., D.W., P.M.S.)
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona (J.E.M., K.G.H., S.R., L.J.M.) and Drug Discovery Biology and Australian Research Council Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia (S.J.P., A.C., D.W., P.M.S.)
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4
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van der Velden WJC, Lindquist P, Madsen JS, Stassen RHMJ, Wewer Albrechtsen NJ, Holst JJ, Hauser AS, Rosenkilde MM. Molecular and in vivo phenotyping of missense variants of the human glucagon receptor. J Biol Chem 2021; 298:101413. [PMID: 34801547 PMCID: PMC8829087 DOI: 10.1016/j.jbc.2021.101413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 11/04/2021] [Accepted: 11/11/2021] [Indexed: 01/09/2023] Open
Abstract
Naturally occurring missense variants of G protein–coupled receptors with loss of function have been linked to metabolic disease in case studies and in animal experiments. The glucagon receptor, one such G protein–coupled receptor, is involved in maintaining blood glucose and amino acid homeostasis; however, loss-of-function mutations of this receptor have not been systematically characterized. Here, we observed fewer glucagon receptor missense variants than expected, as well as lower allele diversity and fewer variants with trait associations as compared with other class B1 receptors. We performed molecular pharmacological phenotyping of 38 missense variants located in the receptor extracellular domain, at the glucagon interface, or with previously suggested clinical implications. These variants were characterized in terms of cAMP accumulation to assess glucagon-induced Gαs coupling, and of recruitment of β-arrestin-1/2. Fifteen variants were impaired in at least one of these downstream functions, with six variants affected in both cAMP accumulation and β-arrestin-1/2 recruitment. For the eight variants with decreased Gαs signaling (D63ECDN, P86ECDS, V96ECDE, G125ECDC, R2253.30H, R3085.40W, V3686.59M, and R3787.35C) binding experiments revealed preserved glucagon affinity, although with significantly reduced binding capacity. Finally, using the UK Biobank, we found that variants with wildtype-like Gαs signaling did not associate with metabolic phenotypes, whereas carriers of cAMP accumulation-impairing variants displayed a tendency toward increased risk of obesity and increased body mass and blood pressure. These observations are in line with the essential role of the glucagon system in metabolism and support that Gαs is the main signaling pathway effecting the physiological roles of the glucagon receptor.
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Affiliation(s)
- Wijnand J C van der Velden
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Lindquist
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jakob S Madsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Roderick H M J Stassen
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences University of Copenhagen, Copenhagen, Denmark; Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences University of Copenhagen, Copenhagen, Denmark
| | - Alexander S Hauser
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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5
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Li J, Guo S, Chai F, Sun Q, Li P, Gao L, Dai L, Ouyang X, Zhou Z, Zhou L, Cheng W, Qi S, Lu K, Ren H. Genetically incorporated crosslinkers reveal NleE attenuates host autophagy dependent on PSMD10. eLife 2021; 10:e69047. [PMID: 34254583 PMCID: PMC8324295 DOI: 10.7554/elife.69047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/13/2021] [Indexed: 02/05/2023] Open
Abstract
Autophagy acts as a pivotal innate immune response against infection. Some virulence effectors subvert the host autophagic machinery to escape the surveillance of autophagy. The mechanism by which pathogens interact with host autophagy remains mostly unclear. However, traditional strategies often have difficulty identifying host proteins that interact with effectors due to the weak, dynamic, and transient nature of these interactions. Here, we found that Enteropathogenic Escherichia coli (EPEC) regulates autophagosome formation in host cells dependent on effector NleE. The 26S Proteasome Regulatory Subunit 10 (PSMD10) was identified as a direct interaction partner of NleE in living cells by employing genetically incorporated crosslinkers. Pairwise chemical crosslinking revealed that NleE interacts with the N-terminus of PSMD10. We demonstrated that PSMD10 homodimerization is necessary for its interaction with ATG7 and promotion of autophagy, but not necessary for PSMD10 interaction with ATG12. Therefore, NleE-mediated PSMD10 in monomeric state attenuates host autophagosome formation. Our study reveals the mechanism through which EPEC attenuates host autophagy activity.
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Affiliation(s)
- Jingxiang Li
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Shupan Guo
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Fangni Chai
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Qi Sun
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Pan Li
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Li Gao
- Department of General Practice and National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, and Sichuan UniversityChengduChina
| | - Lunzhi Dai
- Department of General Practice and National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, and Sichuan UniversityChengduChina
| | - Xiaoxiao Ouyang
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Zhihui Zhou
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Li Zhou
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Wei Cheng
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Shiqian Qi
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Kefeng Lu
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
| | - Haiyan Ren
- Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of BiotherapyChengduChina
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6
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Mobbs JI, Belousoff MJ, Harikumar KG, Piper SJ, Xu X, Furness SGB, Venugopal H, Christopoulos A, Danev R, Wootten D, Thal DM, Miller LJ, Sexton PM. Structures of the human cholecystokinin 1 (CCK1) receptor bound to Gs and Gq mimetic proteins provide insight into mechanisms of G protein selectivity. PLoS Biol 2021; 19:e3001295. [PMID: 34086670 PMCID: PMC8208569 DOI: 10.1371/journal.pbio.3001295] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 06/16/2021] [Accepted: 05/19/2021] [Indexed: 01/08/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are critical regulators of cellular function acting via heterotrimeric G proteins as their primary transducers with individual GPCRs capable of pleiotropic coupling to multiple G proteins. Structural features governing G protein selectivity and promiscuity are currently unclear. Here, we used cryo-electron microscopy (cryo-EM) to determine structures of the cholecystokinin (CCK) type 1 receptor (CCK1R) bound to the CCK peptide agonist, CCK-8 and 2 distinct transducer proteins, its primary transducer Gq, and the more weakly coupled Gs. As seen with other Gq/11-GPCR complexes, the Gq-α5 helix (αH5) bound to a relatively narrow pocket in the CCK1R core. Surprisingly, the backbone of the CCK1R and volume of the G protein binding pocket were essentially equivalent when Gs was bound, with the Gs αH5 displaying a conformation that arises from "unwinding" of the far carboxyl-terminal residues, compared to canonically Gs coupled receptors. Thus, integrated changes in the conformations of both the receptor and G protein are likely to play critical roles in the promiscuous coupling of individual GPCRs.
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MESH Headings
- Cholecystokinin/metabolism
- Cholesterol/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11/chemistry
- GTP-Binding Protein alpha Subunits, Gq-G11/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11/ultrastructure
- GTP-Binding Protein alpha Subunits, Gs/chemistry
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- GTP-Binding Protein alpha Subunits, Gs/ultrastructure
- HEK293 Cells
- Humans
- Models, Molecular
- Protein Binding
- Receptors, Cholecystokinin/chemistry
- Receptors, Cholecystokinin/metabolism
- Receptors, Cholecystokinin/ultrastructure
- Signal Transduction
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Affiliation(s)
- Jesse I. Mobbs
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Matthew J. Belousoff
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Kaleeckal G. Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona, United States of America
| | - Sarah J. Piper
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Xiaomeng Xu
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Sebastian G. B. Furness
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Hari Venugopal
- Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, Victoria, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Radostin Danev
- Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Denise Wootten
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - David M. Thal
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Laurence J. Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona, United States of America
| | - Patrick M. Sexton
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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7
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Capturing Peptide-GPCR Interactions and Their Dynamics. Molecules 2020; 25:molecules25204724. [PMID: 33076289 PMCID: PMC7587574 DOI: 10.3390/molecules25204724] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/08/2020] [Accepted: 10/09/2020] [Indexed: 12/16/2022] Open
Abstract
Many biological functions of peptides are mediated through G protein-coupled receptors (GPCRs). Upon ligand binding, GPCRs undergo conformational changes that facilitate the binding and activation of multiple effectors. GPCRs regulate nearly all physiological processes and are a favorite pharmacological target. In particular, drugs are sought after that elicit the recruitment of selected effectors only (biased ligands). Understanding how ligands bind to GPCRs and which conformational changes they induce is a fundamental step toward the development of more efficient and specific drugs. Moreover, it is emerging that the dynamic of the ligand–receptor interaction contributes to the specificity of both ligand recognition and effector recruitment, an aspect that is missing in structural snapshots from crystallography. We describe here biochemical and biophysical techniques to address ligand–receptor interactions in their structural and dynamic aspects, which include mutagenesis, crosslinking, spectroscopic techniques, and mass-spectrometry profiling. With a main focus on peptide receptors, we present methods to unveil the ligand–receptor contact interface and methods that address conformational changes both in the ligand and the GPCR. The presented studies highlight a wide structural heterogeneity among peptide receptors, reveal distinct structural changes occurring during ligand binding and a surprisingly high dynamics of the ligand–GPCR complexes.
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8
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Dong M, Deganutti G, Piper SJ, Liang YL, Khoshouei M, Belousoff MJ, Harikumar KG, Reynolds CA, Glukhova A, Furness SGB, Christopoulos A, Danev R, Wootten D, Sexton PM, Miller LJ. Structure and dynamics of the active Gs-coupled human secretin receptor. Nat Commun 2020; 11:4137. [PMID: 32811827 PMCID: PMC7435274 DOI: 10.1038/s41467-020-17791-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 07/15/2020] [Indexed: 01/08/2023] Open
Abstract
The class B secretin GPCR (SecR) has broad physiological effects, with target potential for treatment of metabolic and cardiovascular disease. Molecular understanding of SecR binding and activation is important for its therapeutic exploitation. We combined cryo-electron microscopy, molecular dynamics, and biochemical cross-linking to determine a 2.3 Å structure, and interrogate dynamics, of secretin bound to the SecR:Gs complex. SecR exhibited a unique organization of its extracellular domain (ECD) relative to its 7-transmembrane (TM) core, forming more extended interactions than other family members. Numerous polar interactions formed between secretin and the receptor extracellular loops (ECLs) and TM helices. Cysteine-cross-linking, cryo-electron microscopy multivariate analysis and molecular dynamics simulations revealed that interactions between peptide and receptor were dynamic, and suggested a model for initial peptide engagement where early interactions between the far N-terminus of the peptide and SecR ECL2 likely occur following initial binding of the peptide C-terminus to the ECD.
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Affiliation(s)
- Maoqing Dong
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA
| | - Giuseppe Deganutti
- School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.,Centre for Sport, Exercise and Life Sciences, Faculty of Health and Life Sciences, Alison Gingell Building, Coventry University, CV1 2DS, Coventry, UK
| | - Sarah J Piper
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Yi-Lynn Liang
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Maryam Khoshouei
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.,Novartis Institutes for Biomedical Research, Novartis Pharma AG, 4002, Basel, Switzerland
| | - Matthew J Belousoff
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Kaleeckal G Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA
| | | | - Alisa Glukhova
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Radostin Danev
- Graduate School of Medicine, University of Tokyo, N415, 7-3-1 Hongo, Bunkyo-ku, 113-0033, Tokyo, Japan
| | - Denise Wootten
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
| | - Patrick M Sexton
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA.
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9
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Seidel L, Zarzycka B, Katritch V, Coin I. Exploring Pairwise Chemical Crosslinking To Study Peptide-Receptor Interactions. Chembiochem 2019; 20:683-692. [PMID: 30565820 DOI: 10.1002/cbic.201800582] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Indexed: 01/29/2023]
Abstract
Pairwise crosslinking is a powerful technique to characterize interactions between G protein coupled receptors and their ligands in the live cell. In this work, the "thiol trapping" method, which exploits the proximity-enhanced reaction between haloacetamides and cysteine, is examined to identify intermolecular pairs of vicinal positions. By incorporating cysteine into the corticotropin-releasing factor receptor and either α-chloro- or α-bromoacetamide groups into its ligands, it is shown that thiol trapping provides highly reproducible signals and a low background, and represents a valid alternative to classical "disulfide trapping". The method is advantageous if reducing agents are required during sample analysis. Moreover, it can provide partially distinct spatial constraints, thus giving access to a wider dataset for molecular modeling. Finally, by applying recombinant mini-Gs, GTPγS, and Gαs-depleted HEK293 cells to modulate Gs coupling, it is shown that yields of crosslinking increase in the presence of elevated levels of Gs.
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Affiliation(s)
- Lisa Seidel
- Faculty of Life Sciences, Institute of Biochemistry, University of Leipzig, Bruederstrasse 34, 04103, Leipzig, Germany
| | - Barbara Zarzycka
- Department of Biological Sciences, Bridge Institute, University of Southern California, 1002 Childs Way, MCB 317, Los Angeles, CA, 90089-3502, USA
| | - Vsevolod Katritch
- Department of Biological Sciences, Bridge Institute, University of Southern California, 1002 Childs Way, MCB 317, Los Angeles, CA, 90089-3502, USA.,Department of Chemistry, Bridge Institute, University of Southern California, 1002 Childs Way, MCB 317, Los Angeles, CA, 90089-3502, USA
| | - Irene Coin
- Faculty of Life Sciences, Institute of Biochemistry, University of Leipzig, Bruederstrasse 34, 04103, Leipzig, Germany
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10
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Karageorgos V, Venihaki M, Sakellaris S, Pardalos M, Kontakis G, Matsoukas MT, Gravanis A, Margioris A, Liapakis G. Current understanding of the structure and function of family B GPCRs to design novel drugs. Hormones (Athens) 2018; 17:45-59. [PMID: 29858864 DOI: 10.1007/s42000-018-0009-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 01/25/2018] [Indexed: 01/10/2023]
Abstract
Family B of G-protein-coupled receptors (GPCRs) and their ligands play a central role in a number of homeostatic mechanisms in the endocrine, gastrointestinal, skeletal, immune, cardiovascular and central nervous systems. Alterations in family B GPCR-regulated homeostatic mechanisms may cause a variety of potentially life-threatening conditions, signifying the necessity to develop novel ligands targeting these receptors. Obtaining structural and functional information on family B GPCRs will accelerate the development of novel drugs to target these receptors. Family B GPCRs are proteins that span the plasma membrane seven times, thus forming seven transmembrane domains (TM1-TM7) which are connected to each other by three extracellular (EL) and three intracellular (IL) loops. In addition, these receptors have a long extracellular N-domain and an intracellular C-tail. The upper parts of the TMs and ELs form the J-domain of receptors. The C-terminal region of peptides first binds to the N-domain of receptors. This 'first-step' interaction orients the N-terminal region of peptides towards the J-domain of receptors, thus resulting in a 'second-step' of ligand-receptor interaction that activates the receptor. Activation-associated structural changes of receptors are transmitted through TMs to their intracellular regions and are responsible for their interaction with the G proteins and activation of the latter, thus resulting in a biological effect. This review summarizes the current information regarding the structure and function of family B GPCRs and their physiological and pathophysiological roles.
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Affiliation(s)
- Vlasios Karageorgos
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece
| | - Maria Venihaki
- Department of Clinical Chemistry, School of Medicine, University of Crete, Heraklion, Crete, Greece
| | - Stelios Sakellaris
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece
| | - Michail Pardalos
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece
| | - George Kontakis
- Department of Orthopedics, University Hospital of Heraklion, Crete, Greece
| | | | - Achille Gravanis
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece
| | - Andreas Margioris
- Department of Clinical Chemistry, School of Medicine, University of Crete, Heraklion, Crete, Greece
| | - George Liapakis
- Department of Pharmacology, School of Medicine, University of Crete, Voutes, 71003, Heraklion, Crete, Greece.
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11
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Extending the Structural View of Class B GPCRs. Trends Biochem Sci 2017; 42:946-960. [PMID: 29132948 DOI: 10.1016/j.tibs.2017.10.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 10/02/2017] [Accepted: 10/09/2017] [Indexed: 01/27/2023]
Abstract
The secretin-like class B family of G protein-coupled receptors (GPCRs) are key players in hormonal homeostasis. Recent structures of various receptors in complex with a variety of orthosteric and allosteric ligands provide fundamental new insights into the function and mechanism of class B GPCRs, including: (i) ligand-induced changes in the relative orientation of the extracellular and transmembrane receptor domains; (ii) intramolecular interaction networks that stabilize conformational changes to accommodate intracellular G protein binding; and (iii) allosteric modulation of receptor activation. This review provides a comprehensive analysis of the structural, biochemical, and pharmacological data on class B GPCRs for understanding ligand-receptor interaction and modulation mechanisms and assessing the potential implications for drug discovery for the secretin-like GPCR family.
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12
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Ramil CP, Dong M, An P, Lewandowski TM, Yu Z, Miller LJ, Lin Q. Spirohexene-Tetrazine Ligation Enables Bioorthogonal Labeling of Class B G Protein-Coupled Receptors in Live Cells. J Am Chem Soc 2017; 139:13376-13386. [PMID: 28876923 DOI: 10.1021/jacs.7b05674] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A new bioorthogonal reactant pair, spiro[2.3]hex-1-ene (Sph) and 3,6-di(2-pyridyl)-s-tetrazine (DpTz), for the strain-promoted inverse electron-demand Diels-Alder cycloaddition, that is, tetrazine ligation, is reported. As compared to the previously reported strained alkenes such as trans-cyclooctene (TCO) and 1,3-disubstituted cyclopropene, Sph exhibits balanced reactivity and stability in tetrazine ligation with the protein substrates. A lysine derivative of Sph, SphK, was site-selectively incorporated into the extracellular loop regions (ECLs) of GCGR and GLP-1R, two members of class B G protein-coupled receptors (GPCRs) in mammalian cells with the incorporation efficiency dependent on the location. Subsequent bioorthogonal reactions with the fluorophore-conjugated DpTz reagents afforded the fluorescently labeled GCGR and GLP-1R ECL mutants with labeling yield as high as 68%. A multitude of functional assays were performed with these GPCR mutants, including ligand binding, ligand-induced receptor internalization, and ligand-stimulated intracellular cAMP accumulation. Several positions in the ECL3s of GCGR and GLP-1R were identified that tolerate SphK mutagenesis and subsequent bioorthogonal labeling. The generation of functional, fluorescently labeled ECL3 mutants of GCGR and GLP-1R should allow biophysical studies of conformation dynamics of this important class of GPCRs in their native environment in live cells.
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Affiliation(s)
- Carlo P Ramil
- Department of Chemistry, State University of New York at Buffalo , Buffalo, New York 14260-3000, United States
| | - Maoqing Dong
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Scottsdale, Arizona 85259, United States
| | - Peng An
- Department of Chemistry, State University of New York at Buffalo , Buffalo, New York 14260-3000, United States
| | - Tracey M Lewandowski
- Department of Chemistry, State University of New York at Buffalo , Buffalo, New York 14260-3000, United States
| | - Zhipeng Yu
- Department of Chemistry, State University of New York at Buffalo , Buffalo, New York 14260-3000, United States
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Scottsdale, Arizona 85259, United States
| | - Qing Lin
- Department of Chemistry, State University of New York at Buffalo , Buffalo, New York 14260-3000, United States
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13
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Woolley MJ, Conner AC. Understanding the common themes and diverse roles of the second extracellular loop (ECL2) of the GPCR super-family. Mol Cell Endocrinol 2017; 449:3-11. [PMID: 27899324 DOI: 10.1016/j.mce.2016.11.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/02/2016] [Accepted: 11/24/2016] [Indexed: 11/16/2022]
Abstract
The extracellular loops (ECLs) of G protein-coupled receptors (GPCRs) can bind directly to docked orthosteric or allosteric ligands, they can contain transient contact points for ligand entry into the transmembrane (TM) bundle and they can regulate the activation of the receptor signalling pathways. Of the three ECLs, ECL2 is the largest and most structurally diverse reflecting its functional importance. This has been shown through biochemical techniques and has been supported by the many subsequent crystal structures of GPCRs bound to both agonists and antagonists. ECL2 shares common structural features between (and sometimes across) receptor sub-families and can facilitate ligand entry to the TM core or act directly as a surface of the ligand-binding pocket. Structural similarities seem to underpin common binding mechanisms; however, where these exist, variations in primary sequence ensure ligand-binding specificity. This review will compare current understanding of the structural themes and main functional roles of ECL2 in ligand binding, activation and regulation of the major families of GPCRs.
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Affiliation(s)
- Michael J Woolley
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Alex C Conner
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
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14
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Wootten D, Reynolds CA, Smith KJ, Mobarec JC, Koole C, Savage EE, Pabreja K, Simms J, Sridhar R, Furness SGB, Liu M, Thompson PE, Miller LJ, Christopoulos A, Sexton PM. The Extracellular Surface of the GLP-1 Receptor Is a Molecular Trigger for Biased Agonism. Cell 2017; 165:1632-1643. [PMID: 27315480 PMCID: PMC4912689 DOI: 10.1016/j.cell.2016.05.023] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/16/2016] [Accepted: 05/03/2016] [Indexed: 12/25/2022]
Abstract
Ligand-directed signal bias offers opportunities for sculpting molecular events, with the promise of better, safer therapeutics. Critical to the exploitation of signal bias is an understanding of the molecular events coupling ligand binding to intracellular signaling. Activation of class B G protein-coupled receptors is driven by interaction of the peptide N terminus with the receptor core. To understand how this drives signaling, we have used advanced analytical methods that enable separation of effects on pathway-specific signaling from those that modify agonist affinity and mapped the functional consequence of receptor modification onto three-dimensional models of a receptor-ligand complex. This yields molecular insights into the initiation of receptor activation and the mechanistic basis for biased agonism. Our data reveal that peptide agonists can engage different elements of the receptor extracellular face to achieve effector coupling and biased signaling providing a foundation for rational design of biased agonists. Effect of mutation on affinity and efficacy of biased ligands mapped onto 3D models Biased agonists form distinct interactions with the GLP-1R extracellular surface Engagement of unique elements of the extracellular surface promotes biased agonism Insights into class B GPCR activation/biased agonism can aid rational drug design
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Affiliation(s)
- Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
| | | | - Kevin J Smith
- School of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK
| | - Juan C Mobarec
- School of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK
| | - Cassandra Koole
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia; Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Emilia E Savage
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Kavita Pabreja
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - John Simms
- School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK
| | - Rohan Sridhar
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Sebastian G B Furness
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Mengjie Liu
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Philip E Thompson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ 85259, USA
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
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15
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Yang D, de Graaf C, Yang L, Song G, Dai A, Cai X, Feng Y, Reedtz-Runge S, Hanson MA, Yang H, Jiang H, Stevens RC, Wang MW. Structural Determinants of Binding the Seven-transmembrane Domain of the Glucagon-like Peptide-1 Receptor (GLP-1R). J Biol Chem 2016; 291:12991-3004. [PMID: 27059958 DOI: 10.1074/jbc.m116.721977] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Indexed: 12/25/2022] Open
Abstract
The glucagon-like peptide-1 receptor (GLP-1R) belongs to the secretin-like (class B) family of G protein-coupled receptors. Members of the class B family are distinguished by their large extracellular domain, which works cooperatively with the canonical seven-transmembrane (7TM) helical domain to signal in response to binding of various peptide hormones. We have combined structure-based site-specific mutational studies with molecular dynamics simulations of a full-length model of GLP-1R bound to multiple peptide ligand variants. Despite the high sequence similarity between GLP-1R and its closest structural homologue, the glucagon receptor (GCGR), nearly half of the 62 stably expressed mutants affected GLP-1R in a different manner than the corresponding mutants in GCGR. The molecular dynamics simulations of wild-type and mutant GLP-1R·ligand complexes provided molecular insights into GLP-1R-specific recognition mechanisms for the N terminus of GLP-1 by residues in the 7TM pocket and explained how glucagon-mimicking GLP-1 mutants restored binding affinity for (GCGR-mimicking) GLP-1R mutants. Structural analysis of the simulations suggested that peptide ligand binding mode variations in the 7TM binding pocket are facilitated by movement of the extracellular domain relative to the 7TM bundle. These differences in binding modes may account for the pharmacological differences between GLP-1 peptide variants.
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Affiliation(s)
- Dehua Yang
- From The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 189 Guo Shou Jing Road, Shanghai 201203, China
| | - Chris de Graaf
- the Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Linlin Yang
- the Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
| | - Gaojie Song
- the iHuman Institute, ShanghaiTech University, 99 Haike Road, Shanghai 201203, China
| | - Antao Dai
- From The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 189 Guo Shou Jing Road, Shanghai 201203, China
| | - Xiaoqing Cai
- From The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 189 Guo Shou Jing Road, Shanghai 201203, China
| | - Yang Feng
- From The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 189 Guo Shou Jing Road, Shanghai 201203, China
| | - Steffen Reedtz-Runge
- the Department of Protein Structure, Novo Nordisk, Novo Nordisk Park, Malov 2760, Denmark
| | | | - Huaiyu Yang
- the Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
| | - Hualiang Jiang
- the Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
| | - Raymond C Stevens
- the iHuman Institute, ShanghaiTech University, 99 Haike Road, Shanghai 201203, China, the Bridge Institute, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, California 90089, and
| | - Ming-Wei Wang
- From The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 189 Guo Shou Jing Road, Shanghai 201203, China, the School of Pharmacy, Fudan University, 826 Zhang Heng Road, Shanghai 201203, China
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16
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Wootten D, Miller LJ, Koole C, Christopoulos A, Sexton PM. Allostery and Biased Agonism at Class B G Protein-Coupled Receptors. Chem Rev 2016; 117:111-138. [PMID: 27040440 DOI: 10.1021/acs.chemrev.6b00049] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Class B G protein-coupled receptors (GPCRs) respond to paracrine or endocrine peptide hormones involved in control of bone homeostasis, glucose regulation, satiety, and gastro-intestinal function, as well as pain transmission. These receptors are targets for existing drugs that treat osteoporosis, hypercalcaemia, Paget's disease, type II diabetes, and obesity and are being actively pursued as targets for numerous other diseases. Exploitation of class B receptors has been limited by difficulties with small molecule drug discovery and development and an under appreciation of factors governing optimal therapeutic efficacy. Recently, there has been increasing awareness of novel attributes of GPCR function that offer new opportunity for drug development. These include the presence of allosteric binding sites on the receptor that can be exploited as drug binding pockets and the ability of individual drugs to enrich subpopulations of receptor conformations to selectively control signaling, a phenomenon termed biased agonism. In this review, current knowledge of biased signaling and small molecule allostery within class B GPCRs is discussed, highlighting areas that have progressed significantly over the past decade, in addition to those that remain largely unexplored with respect to these phenomena.
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Affiliation(s)
- Denise Wootten
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville 3052, Victoria, Australia
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Scottsdale, Arizona 85259, United States
| | - Cassandra Koole
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville 3052, Victoria, Australia.,Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University , New York, New York 10065, United States
| | - Arthur Christopoulos
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville 3052, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville 3052, Victoria, Australia
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17
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Kufareva I, Gustavsson M, Holden LG, Qin L, Zheng Y, Handel TM. Disulfide Trapping for Modeling and Structure Determination of Receptor: Chemokine Complexes. Methods Enzymol 2016; 570:389-420. [PMID: 26921956 DOI: 10.1016/bs.mie.2015.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Despite the recent breakthrough advances in GPCR crystallography, structure determination of protein-protein complexes involving chemokine receptors and their endogenous chemokine ligands remains challenging. Here, we describe disulfide trapping, a methodology for generating irreversible covalent binary protein complexes from unbound protein partners by introducing two cysteine residues, one per interaction partner, at selected positions within their interaction interface. Disulfide trapping can serve at least two distinct purposes: (i) stabilization of the complex to assist structural studies and/or (ii) determination of pairwise residue proximities to guide molecular modeling. Methods for characterization of disulfide-trapped complexes are described and evaluated in terms of throughput, sensitivity, and specificity toward the most energetically favorable crosslinks. Due to abundance of native disulfide bonds at receptor:chemokine interfaces, disulfide trapping of their complexes can be associated with intramolecular disulfide shuffling and result in misfolding of the component proteins; because of this, evidence from several experiments is typically needed to firmly establish a positive disulfide crosslink. An optimal pipeline that maximizes throughput and minimizes time and costs by early triage of unsuccessful candidate constructs is proposed.
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Affiliation(s)
- Irina Kufareva
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Martin Gustavsson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Lauren G Holden
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Ling Qin
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Yi Zheng
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Tracy M Handel
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA.
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18
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Dong M, Lam PCH, Orry A, Sexton PM, Christopoulos A, Abagyan R, Miller LJ. Use of Cysteine Trapping to Map Spatial Approximations between Residues Contributing to the Helix N-capping Motif of Secretin and Distinct Residues within Each of the Extracellular Loops of Its Receptor. J Biol Chem 2016; 291:5172-84. [PMID: 26740626 DOI: 10.1074/jbc.m115.706010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Indexed: 12/31/2022] Open
Abstract
Amino-terminal regions of secretin-family peptides contain key determinants for biological activity and binding specificity, although the nature of interactions with receptors is unclear. A helix N-capping motif within this region has been postulated to directly contribute to agonist activity while also stabilizing formation of a helix extending toward the peptide carboxyl terminus and docking within the receptor amino terminus. We used cysteine trapping to systematically explore spatial approximations between cysteines replacing each residue in this motif of secretin (sec), Phe(6), Thr(7), and Leu(10), and cysteines incorporated into the extracellular face of the receptor. Each peptide was a full agonist for cAMP, but had a lower binding affinity than natural hormone. These bound to COS cells expressing 61 receptor constructs incorporating cysteines in every position along each extracellular loop (ECL) and adjacent parts of transmembrane (TM) segments. Patterns of covalent labeling were distinct for each probe, with Cys(6)-sec labeling multiple residues in the carboxyl-terminal half of ECL2 and throughout ECL3, Cys(7)-sec predominantly labeling only single residues in the carboxyl-terminal end of ECL2 and the amino-terminal end of ECL3, and Cys(10)-sec not efficiently labeling any of these residues. These spatial constraints were used to refine our model of secretin bound to its receptor, now bringing ECL3 above the amino terminus of the ligand and revealing possible charge-charge interactions between this part of secretin and receptor residues in TM5, TM6, ECL2, and ECL3, which can orient and stabilize the peptide-receptor complex. This was validated by testing predicted approximations by mutagenesis and residue-residue complementation studies.
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Affiliation(s)
- Maoqing Dong
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona 85259
| | | | | | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville 3052, Australia, and
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville 3052, Australia, and
| | - Ruben Abagyan
- Molsoft LLC, La Jolla, California 92037, the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92037
| | - Laurence J Miller
- From the Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona 85259,
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19
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Culhane KJ, Liu Y, Cai Y, Yan ECY. Transmembrane signal transduction by peptide hormones via family B G protein-coupled receptors. Front Pharmacol 2015; 6:264. [PMID: 26594176 PMCID: PMC4633518 DOI: 10.3389/fphar.2015.00264] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/23/2015] [Indexed: 01/28/2023] Open
Abstract
Although family B G protein-coupled receptors (GPCRs) contain only 15 members, they play key roles in transmembrane signal transduction of hormones. Family B GPCRs are drug targets for developing therapeutics for diseases ranging from metabolic to neurological disorders. Despite their importance, the molecular mechanism of activation of family B GPCRs remains largely unexplored due to the challenges in expression and purification of functional receptors to the quantity for biophysical characterization. Currently, there is no crystal structure available of a full-length family B GPCR. However, structures of key domains, including the extracellular ligand binding regions and seven-helical transmembrane regions, have been solved by X-ray crystallography and NMR, providing insights into the mechanisms of ligand recognition and selectivity, and helical arrangements within the cell membrane. Moreover, biophysical and biochemical methods have been used to explore functions, key residues for signaling, and the kinetics and dynamics of signaling processes. This review summarizes the current knowledge of the signal transduction mechanism of family B GPCRs at the molecular level and comments on the challenges and outlook for mechanistic studies of family B GPCRs.
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Affiliation(s)
- Kelly J Culhane
- Department of Molecular Biophysics and Biochemistry, Yale University New Haven, CT, USA
| | - Yuting Liu
- Department of Chemistry, Yale University New Haven, CT, USA
| | - Yingying Cai
- Department of Chemistry, Yale University New Haven, CT, USA
| | - Elsa C Y Yan
- Department of Chemistry, Yale University New Haven, CT, USA
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20
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Conformational states of the full-length glucagon receptor. Nat Commun 2015; 6:7859. [PMID: 26227798 PMCID: PMC4532856 DOI: 10.1038/ncomms8859] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 06/18/2015] [Indexed: 01/06/2023] Open
Abstract
Class B G protein-coupled receptors are composed of an extracellular domain (ECD) and a seven-transmembrane (7TM) domain, and their signalling is regulated by peptide hormones. Using a hybrid structural biology approach together with the ECD and 7TM domain crystal structures of the glucagon receptor (GCGR), we examine the relationship between full-length receptor conformation and peptide ligand binding. Molecular dynamics (MD) and disulfide crosslinking studies suggest that apo-GCGR can adopt both an open and closed conformation associated with extensive contacts between the ECD and 7TM domain. The electron microscopy (EM) map of the full-length GCGR shows how a monoclonal antibody stabilizes the ECD and 7TM domain in an elongated conformation. Hydrogen/deuterium exchange (HDX) studies and MD simulations indicate that an open conformation is also stabilized by peptide ligand binding. The combined studies reveal the open/closed states of GCGR and suggest that glucagon binds to GCGR by a conformational selection mechanism.
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21
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Tyagi S, Lemke EA. Single-molecule FRET and crosslinking studies in structural biology enabled by noncanonical amino acids. Curr Opin Struct Biol 2015; 32:66-73. [DOI: 10.1016/j.sbi.2015.02.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 01/24/2015] [Accepted: 02/05/2015] [Indexed: 10/23/2022]
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22
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Abstract
Experimental structure determination for G protein-coupled receptors (GPCRs) and especially their complexes with protein and peptide ligands is at its infancy. In the absence of complex structures, molecular modeling and docking play a large role not only by providing a proper 3D context for interpretation of biochemical and biophysical data, but also by prospectively guiding experiments. Experimentally confirmed restraints may help improve the accuracy and information content of the computational models. Here we present a hybrid molecular modeling protocol that integrates heterogeneous experimental data with force field-based calculations in the stochastic global optimization of the conformations and relative orientations of binding partners. Some experimental data, such as pharmacophore-like chemical fields or disulfide-trapping restraints, can be seamlessly incorporated in the protocol, while other types of data are more useful at the stage of solution filtering. The protocol was successfully applied to modeling and design of a stable construct that resulted in crystallization of the first complex between a chemokine and its receptor. Examples from this work are used to illustrate the steps of the protocol. The utility of different types of experimental data for modeling and docking is discussed and caveats associated with data misinterpretation are highlighted.
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23
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Grover S, Dhanjal JK, Goyal S, Grover A, Sundar D. Computational identification of novel natural inhibitors of glucagon receptor for checking type II diabetes mellitus. BMC Bioinformatics 2014; 15 Suppl 16:S13. [PMID: 25521597 PMCID: PMC4290642 DOI: 10.1186/1471-2105-15-s16-s13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Interaction of the small peptide hormone glucagon with glucagon receptor (GCGR) stimulates the release of glucose from the hepatic cells during fasting; hence GCGR performs a significant function in glucose homeostasis. Inhibiting the interaction between glucagon and its receptor has been reported to control hepatic glucose overproduction and thus GCGR has evolved as an attractive therapeutic target for the treatment of type II diabetes mellitus. RESULTS In the present study, a large library of natural compounds was screened against 7 transmembrane domain of GCGR to identify novel therapeutic molecules that can inhibit the binding of glucagon with GCGR. Molecular dynamics simulations were performed to study the dynamic behaviour of the docked complexes and the molecular interactions between the screened compounds and the ligand binding residues of GCGR were analysed in detail. The top scoring compounds were also compared with already documented GCGR inhibitors- MK-0893 and LY2409021 for their binding affinity and other ADME properties. Finally, we have reported two natural drug like compounds PIB and CAA which showed good binding affinity for GCGR and are potent inhibitor of its functional activity. CONCLUSION This study contributes evidence for application of these compounds as prospective small ligand molecules against type II diabetes. Novel natural drug like inhibitors against the 7 transmembrane domain of GCGR have been identified which showed high binding affinity and potent inhibition of GCGR.
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Dong M, Koole C, Wootten D, Sexton PM, Miller LJ. Structural and functional insights into the juxtamembranous amino-terminal tail and extracellular loop regions of class B GPCRs. Br J Pharmacol 2014; 171:1085-101. [PMID: 23889342 DOI: 10.1111/bph.12293] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/22/2013] [Accepted: 06/29/2013] [Indexed: 12/24/2022] Open
Abstract
Class B guanine nucleotide-binding protein GPCRs share heptahelical topology and signalling via coupling with heterotrimeric G proteins typical of the entire superfamily of GPCRs. However, they also exhibit substantial structural differences from the more extensively studied class A GPCRs. Even their helical bundle region, most conserved across the superfamily, is predicted to differ from that of class A GPCRs. Much is now known about the conserved structure of the amino-terminal domain of class B GPCRs, coming from isolated NMR and crystal structures, but the orientation of that domain relative to the helical bundle is unknown, and even less is understood about the conformations of the juxtamembranous amino-terminal tail or of the extracellular loops linking the transmembrane segments. We now review what is known about the structure and function of these regions of class B GPCRs. This comes from indirect analysis of structure-function relationships elucidated by mutagenesis and/or ligand modification and from the more direct analysis of spatial approximation coming from photoaffinity labelling and cysteine trapping studies. Also reviewed are the limited studies of structure of some of these regions. No dominant theme was recognized for the structures or functional roles of distinct regions of these juxtamembranous portions of the class B GPCRs. Therefore, it is likely that a variety of molecular strategies can be engaged for docking of agonist ligands and for initiation of conformational changes in these receptors that would be expected to converge to a common molecular mechanism for activation of intracellular signalling cascades.
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Affiliation(s)
- M Dong
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, USA
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25
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Abstract
In mammals, secretin is a 27-amino acid peptide that was first studied in 1902 by Bayliss and Starling from the extracts of the jejunal mucosa for its ability to stimulate pancreatic secretion. To date, secretin has only been identified in tetrapods, with the earliest diverged secretin found in frogs. Despite being the first hormone discovered, secretin's evolutionary origin remains enigmatic, it shows moderate sequence identity in nonmammalian tetrapods but is highly conserved in mammals. Current hypotheses suggest that although secretin has already emerged before the divergence of osteichthyans, it was lost in fish and retained only in land vertebrates. Nevertheless, the cognate receptor of secretin has been identified in both actinopterygian fish (zebrafish) and sarcopterygian fish (lungfish). However, the zebrafish secretin receptor was shown to be nonbioactive. Based on the present information that the earliest diverged bioactive secretin receptor was found in lungfish, and its ability to interact with both vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide potently suggested that secretin receptor was descended from a VPAC-like receptor gene before the Actinopterygii-Sarcopterygii split in the vertebrate lineage. Hence, secretin and secretin receptor have gone through independent evolutionary trajectories despite their concurrent emergence post-2R. A functional secretin-secretin receptor axis has probably emerged in the amphibians. Although the pleiotropic actions of secretin are well documented in the literature, only limited information of its physiological functions in nonmammalian tetrapods have been reported. To decipher the structural and functional divergence of secretin and secretin receptor, functional characterization of the ligand-receptor pair in nonmammals would be the next perspective for investigation.
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Affiliation(s)
- Janice K V Tam
- School of Biological SciencesThe University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong
| | - Leo T O Lee
- School of Biological SciencesThe University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong
| | - Jun Jin
- School of Biological SciencesThe University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong
| | - Billy K C Chow
- School of Biological SciencesThe University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong
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26
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Hollenstein K, de Graaf C, Bortolato A, Wang MW, Marshall FH, Stevens RC. Insights into the structure of class B GPCRs. Trends Pharmacol Sci 2013; 35:12-22. [PMID: 24359917 DOI: 10.1016/j.tips.2013.11.001] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/30/2013] [Accepted: 11/01/2013] [Indexed: 02/08/2023]
Abstract
The secretin-like (class B) family of G protein-coupled receptors (GPCRs) are key players in hormonal homeostasis and are interesting drug targets for the treatment of several metabolic disorders (such as type 2 diabetes, osteoporosis, and obesity) and nervous system diseases (such as migraine, anxiety, and depression). The recently solved crystal structures of the transmembrane domains of the human glucagon receptor and human corticotropin-releasing factor receptor 1 have opened up new opportunities to study the structure and function of class B GPCRs. The current review shows how these structures offer more detailed explanations to previous biochemical and pharmacological studies of class B GPCRs, and provides new insights into their interactions with ligands.
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Affiliation(s)
- Kaspar Hollenstein
- Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, UK
| | - Chris de Graaf
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems (AIMMS), VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Andrea Bortolato
- Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, UK
| | - Ming-Wei Wang
- The National Center for Drug Screening and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), 189 Guo Shou Jing Road, Shanghai, 201203, China
| | - Fiona H Marshall
- Heptares Therapeutics Ltd, BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, UK.
| | - Raymond C Stevens
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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27
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Coin I, Katritch V, Sun T, Xiang Z, Siu FY, Beyermann M, Stevens RC, Wang L. Genetically encoded chemical probes in cells reveal the binding path of urocortin-I to CRF class B GPCR. Cell 2013; 155:1258-69. [PMID: 24290358 DOI: 10.1016/j.cell.2013.11.008] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 08/26/2013] [Accepted: 11/07/2013] [Indexed: 01/19/2023]
Abstract
Molecular determinants regulating the activation of class B G-protein-coupled receptors (GPCRs) by native peptide agonists are largely unknown. We have investigated here the interaction between the corticotropin releasing factor receptor type 1 (CRF1R) and its native 40-mer peptide ligand Urocortin-I directly in mammalian cells. By incorporating unnatural amino acid photochemical and new click-chemical probes into the intact receptor expressed in the native membrane of live cells, 44 intermolecular spatial constraints have been derived for the ligand-receptor interaction. The data were analyzed in the context of the recently resolved crystal structure of CRF1R transmembrane domain and existing extracellular domain structures, yielding a complete conformational model for the peptide-receptor complex. Structural features of the receptor-ligand complex yield molecular insights on the mechanism of receptor activation and the basis for discrimination between agonist and antagonist function.
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Affiliation(s)
- Irene Coin
- Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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Woolley MJ, Watkins HA, Taddese B, Karakullukcu ZG, Barwell J, Smith KJ, Hay DL, Poyner DR, Reynolds CA, Conner AC. The role of ECL2 in CGRP receptor activation: a combined modelling and experimental approach. J R Soc Interface 2013; 10:20130589. [PMID: 24047872 PMCID: PMC3785825 DOI: 10.1098/rsif.2013.0589] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The calcitonin gene-related peptide (CGRP) receptor is a complex of a calcitonin receptor-like receptor (CLR), which is a family B G-protein-coupled receptor (GPCR) and receptor activity modifying protein 1. The role of the second extracellular loop (ECL2) of CLR in binding CGRP and coupling to Gs was investigated using a combination of mutagenesis and modelling. An alanine scan of residues 271–294 of CLR showed that the ability of CGRP to produce cAMP was impaired by point mutations at 13 residues; most of these also impaired the response to adrenomedullin (AM). These data were used to select probable ECL2-modelled conformations that are involved in agonist binding, allowing the identification of the likely contacts between the peptide and receptor. The implications of the most likely structures for receptor activation are discussed.
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29
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30
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Structure of the human glucagon class B G-protein-coupled receptor. Nature 2013; 499:444-9. [PMID: 23863937 DOI: 10.1038/nature12393] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 06/17/2013] [Indexed: 12/17/2022]
Abstract
Binding of the glucagon peptide to the glucagon receptor (GCGR) triggers the release of glucose from the liver during fasting; thus GCGR plays an important role in glucose homeostasis. Here we report the crystal structure of the seven transmembrane helical domain of human GCGR at 3.4 Å resolution, complemented by extensive site-specific mutagenesis, and a hybrid model of glucagon bound to GCGR to understand the molecular recognition of the receptor for its native ligand. Beyond the shared seven transmembrane fold, the GCGR transmembrane domain deviates from class A G-protein-coupled receptors with a large ligand-binding pocket and the first transmembrane helix having a 'stalk' region that extends three alpha-helical turns above the plane of the membrane. The stalk positions the extracellular domain (~12 kilodaltons) relative to the membrane to form the glucagon-binding site that captures the peptide and facilitates the insertion of glucagon's amino terminus into the seven transmembrane domain.
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