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Leemann S, Kleinlogel S. Functional optimization of light-activatable Opto-GPCRs: Illuminating the importance of the proximal C-terminus in G-protein specificity. Front Cell Dev Biol 2023; 11:1053022. [PMID: 36936685 PMCID: PMC10014536 DOI: 10.3389/fcell.2023.1053022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 02/14/2023] [Indexed: 03/05/2023] Open
Abstract
Introduction: G-protein coupled receptors (GPCRs) are the largest family of human receptors that transmit signals from natural ligands and pharmaceutical drugs into essentially every physiological process. One main characteristic of G-protein coupled receptors is their ability to specifically couple with different families of G-proteins, thereby triggering specific downstream signaling pathways. While an abundance of structural information is available on G-protein coupled receptorn interactions with G-proteins, little is known about the G-protein coupled receptor domains functionally mediating G-protein specificity, in particular the proximal C-terminus, the structure which cannot be predicted with high confidentiality due to its flexibility. Methods: In this study, we exploited OptoGPCR chimeras between lightgated G-protein coupled receptors (opsins) and ligand-gated G-protein coupled receptors to systematically investigate the involvement of the C-terminus steering G-protein specificity. We employed rhodopsin-beta2-adrenoceptor and melanopsin-mGluR6 chimeras in second messenger assays and developed structural models of the chimeras. Results: We discovered a dominant role of the proximal C-terminus, dictating G-protein selectivity in the melanopsin-mGluR6 chimera, whereas it is the intracellular loop 3, which steers G-protein tropism in the rhodopsin-beta2-adrenoceptor. From the functional results and structural predictions, melanopsin and mGluR6 use a different mechanism to bovine rhodopsin and b2AR to couple to a selective G-protein. Discussion: Collectively, this work adds knowledge to the G-protein coupled receptor domains mediating G-protein selectivity, ultimately paving the way to optogenetically elicited specific G-protein signaling on demand.
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2
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Kotthoff M, Bauer J, Haag F, Krautwurst D. Conserved C-terminal motifs in odorant receptors instruct their cell surface expression and cAMP signaling. FASEB J 2021; 35:e21274. [PMID: 33464692 DOI: 10.1096/fj.202000182rr] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 10/30/2020] [Accepted: 11/30/2020] [Indexed: 11/11/2022]
Abstract
The highly individual plasma membrane expression and cAMP signaling of odorant receptors have hampered their ligand assignment and functional characterization in test cell systems. Chaperones have been identified to support the cell surface expression of only a portion of odorant receptors, with mechanisms remaining unclear. The presence of amino acid motifs that might be responsible for odorant receptors' individual intracellular retention or cell surface expression, and thus, for cAMP signaling, is under debate: so far, no such protein motifs have been suggested. Here, we demonstrate the existence of highly conserved C-terminal amino acid motifs, which discriminate at least between class-I and class-II odorant receptors, with their numbers of motifs increasing during evolution, by comparing C-terminal protein sequences from 4808 receptors across eight species. Truncation experiments and mutation analysis of C-terminal motifs, largely overlapping with helix 8, revealed single amino acids and their combinations to have differential impact on the cell surface expression and on stimulus-dependent cAMP signaling of odorant receptors in NxG 108CC15 cells. Our results demonstrate class-specific and individual C-terminal motif equipment of odorant receptors, which instruct their functional expression in a test cell system, and in situ may regulate their individual cell surface expression and intracellular cAMP signaling.
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Affiliation(s)
| | - Julia Bauer
- Leibniz-Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Franziska Haag
- Leibniz-Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Dietmar Krautwurst
- Leibniz-Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
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Structural Characterization of Receptor-Receptor Interactions in the Allosteric Modulation of G Protein-Coupled Receptor (GPCR) Dimers. Int J Mol Sci 2021; 22:ijms22063241. [PMID: 33810175 PMCID: PMC8005122 DOI: 10.3390/ijms22063241] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/17/2021] [Accepted: 03/20/2021] [Indexed: 01/07/2023] Open
Abstract
G protein-coupled receptor (GPCR) oligomerization, while contentious, continues to attract the attention of researchers. Numerous experimental investigations have validated the presence of GPCR dimers, and the relevance of dimerization in the effectuation of physiological functions intensifies the attractiveness of this concept as a potential therapeutic target. GPCRs, as a single entity, have been the main source of scrutiny for drug design objectives for multiple diseases such as cancer, inflammation, cardiac, and respiratory diseases. The existence of dimers broadens the research scope of GPCR functions, revealing new signaling pathways that can be targeted for disease pathogenesis that have not previously been reported when GPCRs were only viewed in their monomeric form. This review will highlight several aspects of GPCR dimerization, which include a summary of the structural elucidation of the allosteric modulation of class C GPCR activation offered through recent solutions to the three-dimensional, full-length structures of metabotropic glutamate receptor and γ-aminobutyric acid B receptor as well as the role of dimerization in the modification of GPCR function and allostery. With the growing influence of computational methods in the study of GPCRs, we will also be reviewing recent computational tools that have been utilized to map protein-protein interactions (PPI).
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4
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Pal S, Chattopadhyay A. Extramembranous Regions in G Protein-Coupled Receptors: Cinderella in Receptor Biology? J Membr Biol 2019; 252:483-497. [DOI: 10.1007/s00232-019-00092-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022]
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5
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Muller MP, Jiang T, Sun C, Lihan M, Pant S, Mahinthichaichan P, Trifan A, Tajkhorshid E. Characterization of Lipid-Protein Interactions and Lipid-Mediated Modulation of Membrane Protein Function through Molecular Simulation. Chem Rev 2019; 119:6086-6161. [PMID: 30978005 PMCID: PMC6506392 DOI: 10.1021/acs.chemrev.8b00608] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The cellular membrane constitutes one of the most fundamental compartments of a living cell, where key processes such as selective transport of material and exchange of information between the cell and its environment are mediated by proteins that are closely associated with the membrane. The heterogeneity of lipid composition of biological membranes and the effect of lipid molecules on the structure, dynamics, and function of membrane proteins are now widely recognized. Characterization of these functionally important lipid-protein interactions with experimental techniques is however still prohibitively challenging. Molecular dynamics (MD) simulations offer a powerful complementary approach with sufficient temporal and spatial resolutions to gain atomic-level structural information and energetics on lipid-protein interactions. In this review, we aim to provide a broad survey of MD simulations focusing on exploring lipid-protein interactions and characterizing lipid-modulated protein structure and dynamics that have been successful in providing novel insight into the mechanism of membrane protein function.
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Affiliation(s)
- Melanie P. Muller
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tao Jiang
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chang Sun
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Muyun Lihan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shashank Pant
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Paween Mahinthichaichan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Anda Trifan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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6
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Llinas Del Torrent C, Pérez-Benito L, Tresadern G. Computational Drug Design Applied to the Study of Metabotropic Glutamate Receptors. Molecules 2019; 24:molecules24061098. [PMID: 30897742 PMCID: PMC6470756 DOI: 10.3390/molecules24061098] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/15/2019] [Accepted: 03/18/2019] [Indexed: 11/16/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors are a family of eight GPCRs that are attractive drug discovery targets to modulate glutamate action and response. Here we review the application of computational methods to the study of this family of receptors. X-ray structures of the extracellular and 7-transmembrane domains have played an important role to enable structure-based modeling approaches, whilst we also discuss the successful application of ligand-based methods. We summarize the literature and highlight the areas where modeling and experiment have delivered important understanding for mGlu receptor drug discovery. Finally, we offer suggestions of future areas of opportunity for computational work.
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Affiliation(s)
- Claudia Llinas Del Torrent
- Laboratori de Medicina Computacional Unitat de Bioestadistica, Facultat de Medicina, Universitat Autónoma de Barcelona, 08193 Bellaterra, Spain.
| | - Laura Pérez-Benito
- Computational Chemistry, Janssen Research & Development, Janssen Pharmaceutica N. V., Turnhoutseweg 30, B-2340 Beerse, Belgium.
| | - Gary Tresadern
- Computational Chemistry, Janssen Research & Development, Janssen Pharmaceutica N. V., Turnhoutseweg 30, B-2340 Beerse, Belgium.
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7
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Ramírez-Anguita JM, Rodríguez-Espigares I, Guixà-González R, Bruno A, Torrens-Fontanals M, Varela-Rial A, Selent J. Membrane cholesterol effect on the 5-HT 2A receptor: Insights into the lipid-induced modulation of an antipsychotic drug target. Biotechnol Appl Biochem 2017; 65:29-37. [PMID: 28877377 DOI: 10.1002/bab.1608] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The serotonin 5-hydroxytryptamine 2A (5-HT2A ) receptor is a G-protein-coupled receptor (GPCR) relevant for the treatment of CNS disorders. In this regard, neuronal membrane composition in the brain plays a crucial role in the modulation of the receptor functioning. Since cholesterol is an essential component of neuronal membranes, we have studied its effect on the 5-HT2A receptor dynamics through all-atom MD simulations. We find that the presence of cholesterol in the membrane increases receptor conformational variability in most receptor segments. Importantly, detailed structural analysis indicates that conformational variability goes along with the destabilization of hydrogen bonding networks not only within the receptor but also between receptor and lipids. In addition to increased conformational variability, we also find receptor segments with reduced variability. Our analysis suggests that this increased stabilization is the result of stabilizing effects of tightly bound cholesterol molecules to the receptor surface. Our finding contributes to a better understanding of membrane-induced alterations of receptor dynamics and points to cholesterol-induced stabilizing and destabilizing effects on the conformational variability of GPCRs.
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Affiliation(s)
- Juan Manuel Ramírez-Anguita
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Ismael Rodríguez-Espigares
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Ramon Guixà-González
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain.,Institut für Medizinische Physik und Biophysik, Charité, Berlin, Germany
| | - Agostino Bruno
- Department of Pharmacy, Università degli studi di Parma, Italy, Parma
| | - Mariona Torrens-Fontanals
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Alejandro Varela-Rial
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF)-Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
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8
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Fridmanis D, Roga A, Klovins J. ACTH Receptor (MC2R) Specificity: What Do We Know About Underlying Molecular Mechanisms? Front Endocrinol (Lausanne) 2017; 8:13. [PMID: 28220105 PMCID: PMC5292628 DOI: 10.3389/fendo.2017.00013] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 01/16/2017] [Indexed: 11/13/2022] Open
Abstract
Coincidentally, the release of this Research Topic in Frontiers in Endocrinology takes place 25 years after the discovery of the adrenocorticotropic hormone receptor (ACTHR) by Mountjoy and colleagues. In subsequent years, following the discovery of other types of mammalian melanocortin receptors (MCRs), ACTHR also became known as melanocortin type 2 receptor (MC2R). At present, five types of MCRs have been reported, all of which share significant sequence similarity at the amino acid level, and all of which specifically bind melanocortins (MCs)-a group of biologically active peptides generated by proteolysis of the proopiomelanocortin precursor. All MCs share an identical -H-F-R-W- pharmacophore sequence. α-Melanocyte-stimulating hormone (α-MSH) and adrenocorticotropic hormone (ACTH) are the most extensively studied MCs and are derived from the same region. Essentially, α-MSH is formed from the first 13 amino acid residues of ACTH. ACTHR is unique among MCRs because it binds one sole ligand-ACTH, which makes it a very attractive research object for molecular pharmacologists. However, much research has failed, and functional studies of this receptor are lagging behind other MCRs. The reason for these difficulties has already been outlined by Mountjoy and colleagues in their publication on ACTHR coding sequence discovery where the Cloudman S91 melanoma cell line was used for receptor expression because it was a "more sensitive assay system." Subsequent work showed that ACTHR could be successfully expressed only in endogenous MCR-expressing cell lines, since in other cell lines it is retained within the endoplasmic reticulum. The resolution of this methodological problem came in 2005 with the discovery of melanocortin receptor accessory protein, which is required for the formation of functionally active ACTHR. The decade that followed this discovery was filled with exciting research that provided insight into the molecular mechanisms underlying the action of ACTHR. The purpose of this review is to summarize the advances in this fascinating research field.
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Affiliation(s)
| | - Ance Roga
- Latvian Biomedical Research and Study Centre, Riga, Latvia
| | - Janis Klovins
- Latvian Biomedical Research and Study Centre, Riga, Latvia
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9
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Sato T, Kawasaki T, Mine S, Matsumura H. Functional Role of the C-Terminal Amphipathic Helix 8 of Olfactory Receptors and Other G Protein-Coupled Receptors. Int J Mol Sci 2016; 17:ijms17111930. [PMID: 27869740 PMCID: PMC5133925 DOI: 10.3390/ijms17111930] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/09/2016] [Accepted: 11/14/2016] [Indexed: 11/23/2022] Open
Abstract
G protein-coupled receptors (GPCRs) transduce various extracellular signals, such as neurotransmitters, hormones, light, and odorous chemicals, into intracellular signals via G protein activation during neurological, cardiovascular, sensory and reproductive signaling. Common and unique features of interactions between GPCRs and specific G proteins are important for structure-based design of drugs in order to treat GPCR-related diseases. Atomic resolution structures of GPCR complexes with G proteins have revealed shared and extensive interactions between the conserved DRY motif and other residues in transmembrane domains 3 (TM3), 5 and 6, and the target G protein C-terminal region. However, the initial interactions formed between GPCRs and their specific G proteins remain unclear. Alanine scanning mutagenesis of the murine olfactory receptor S6 (mOR-S6) indicated that the N-terminal acidic residue of helix 8 of mOR-S6 is responsible for initial transient and specific interactions with chimeric Gα15_olf, resulting in a response that is 2.2-fold more rapid and 1.7-fold more robust than the interaction with Gα15. Our mutagenesis analysis indicates that the hydrophobic core buried between helix 8 and TM1–2 of mOR-S6 is important for the activation of both Gα15_olf and Gα15. This review focuses on the functional role of the C-terminal amphipathic helix 8 based on several recent GPCR studies.
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Affiliation(s)
- Takaaki Sato
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorioka, Ikeda, Osaka 563-8577, Japan.
| | - Takashi Kawasaki
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorioka, Ikeda, Osaka 563-8577, Japan.
| | - Shouhei Mine
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorioka, Ikeda, Osaka 563-8577, Japan.
| | - Hiroyoshi Matsumura
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
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10
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Bruno A, Aiello F, Costantino G, Radi M. Homology Modeling, Validation and Dynamics of the G Protein-coupled Estrogen Receptor 1 (GPER-1). Mol Inform 2016; 35:333-9. [PMID: 27546037 DOI: 10.1002/minf.201501024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/10/2016] [Indexed: 12/31/2022]
Abstract
Estrogens exert their action mainly by binding three receptors, namely estrogen receptors α and β (ERα and ERβ) and GPER-1 (G-protein coupled estrogen receptor 1). While the patho-physiological role of both ERα and ERβ has been deeply investigated, the role of GPER-1 in estrogens' signaling has not been clearly defined yet. Unfortunately, only few GPER-1 selective ligands were discovered so far, and the real efficiency of such compounds is still matter of debate. To better understand the physiological relevance of GPER-1, new selective chemical probes are higly needed. In this scenario, we report herein the generation and validation of a three-dimensional (3-D) GPER-1 homology model by means of docking studies and molecular dynamics simulations. The model thus generated was employed to (i) decipher the structural basis underlying the ability of estrogens and some Selective Estrogen Receptor Modulators (SERMs) to bind GPER-1 and classical ERα and ERβ, and (ii) generate a reliable G1/GPER-1 complex useful in rationalizing the pharmacological profile of G1 reported in the literature. The G1/GPER-1 complex herein reported could be further exploited in drug design approaches aimed at improving the pharmacological profile of G1 or at identifying new chemical entities (NCEs) as potential modulators of GPER-1.
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Affiliation(s)
- Agostino Bruno
- P4T Group, Dipartimento di Farmacia, Università degli Studi di Parma, Viale delle Scienze, 27/A, 43124, Parma, Italy .
| | - Francesca Aiello
- Dipartimento di Farmacia e Sienze della Salute e della Nutrizione, Università della Calabria, Edificio Polifunzionale, 87036, Arcavacata di Rende (CS, Italy
| | - Gabriele Costantino
- P4T Group, Dipartimento di Farmacia, Università degli Studi di Parma, Viale delle Scienze, 27/A, 43124, Parma, Italy
| | - Marco Radi
- P4T Group, Dipartimento di Farmacia, Università degli Studi di Parma, Viale delle Scienze, 27/A, 43124, Parma, Italy .
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11
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Lange Y, Steck TL. Active membrane cholesterol as a physiological effector. Chem Phys Lipids 2016; 199:74-93. [PMID: 26874289 DOI: 10.1016/j.chemphyslip.2016.02.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/04/2016] [Accepted: 02/08/2016] [Indexed: 02/05/2023]
Abstract
Sterols associate preferentially with plasma membrane sphingolipids and saturated phospholipids to form stoichiometric complexes. Cholesterol in molar excess of the capacity of these polar bilayer lipids has a high accessibility and fugacity; we call this fraction active cholesterol. This review first considers how active cholesterol serves as an upstream regulator of cellular sterol homeostasis. The mechanism appears to utilize the redistribution of active cholesterol down its diffusional gradient to the endoplasmic reticulum and mitochondria, where it binds multiple effectors and directs their feedback activity. We have also reviewed a broad literature in search of a role for active cholesterol (as opposed to bulk cholesterol or lipid domains such as rafts) in the activity of diverse membrane proteins. Several systems provide such evidence, implicating, in particular, caveolin-1, various kinds of ABC-type cholesterol transporters, solute transporters, receptors and ion channels. We suggest that this larger role for active cholesterol warrants close attention and can be tested easily.
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Affiliation(s)
- Yvonne Lange
- Department of Pathology, Rush University Medical Center, 1653 W. Congress Parkway, Chicago, IL 60612, USA.
| | - Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA.
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12
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Helix 3 acts as a conformational hinge in Class A GPCR activation: An analysis of interhelical interaction energies in crystal structures. J Struct Biol 2015; 192:545-553. [PMID: 26522273 DOI: 10.1016/j.jsb.2015.10.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 10/26/2015] [Accepted: 10/28/2015] [Indexed: 01/21/2023]
Abstract
A collection of crystal structures of rhodopsin, β2-adrenergic and adenosine A2A receptors in active, intermediate and inactive states were selected for structural and energetic analyses to identify the changes involved in the activation/deactivation of Class A GPCRs. A set of helix interactions exclusive to either inactive or active/intermediate states were identified. The analysis of these interactions distinguished some local conformational changes involved in receptor activation, in particular, a packing between the intracellular domains of transmembrane helices H3 and H7 and a separation between those of H2 and H6. Also, differential movements of the extracellular and intracellular domains of these helices are apparent. Moreover, a segment of residues in helix H3, including residues L/I3.40 to L3.43, is identified as a key component of the activation mechanism, acting as a conformational hinge between extracellular and intracellular regions. Remarkably, the influence on the activation process of some glutamic and aspartic acidic residues and, as a consequence, the influence of variations on local pH is highlighted. Structural hypotheses that arose from the analysis of rhodopsin, β2-adrenergic and adenosine A2A receptors were tested on the active and inactive M2 muscarinic acetylcholine receptor structures and further discussed in the context of the new mechanistic insights provided by the recently determined active and inactive crystal structures of the μ-opioid receptor. Overall, the structural and energetic analyses of the interhelical interactions present in this collection of Class A GPCRs suggests the existence of a common general activation mechanism featuring a chemical space useful for drug discovery exploration.
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13
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Stornaiuolo M, Bruno A, Botta L, La Regina G, Cosconati S, Silvestri R, Marinelli L, Novellino E. Endogenous vs Exogenous Allosteric Modulators in GPCRs: A dispute for shuttling CB1 among different membrane microenvironments. Sci Rep 2015; 5:15453. [PMID: 26482099 PMCID: PMC4612305 DOI: 10.1038/srep15453] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/21/2015] [Indexed: 11/26/2022] Open
Abstract
A Cannabinoid Receptor 1 (CB1) binding site for the selective allosteric modulator ORG27569 is here identified through an integrate approach of consensus pocket prediction, mutagenesis studies and Mass Spectrometry. This unprecedented ORG27569 pocket presents the structural features of a Cholesterol Consensus Motif, a cholesterol interacting region already found in other GPCRs. ORG27569 and cholesterol affects oppositely CB1 affinity for orthosteric ligands. Moreover, the rise in cholesterol intracellular level results in CB1 trafficking to the axonal region of neuronal cells, while, on the contrary, ORG27568 binding induces CB1 enrichment at the soma. This control of receptor migration among functionally different membrane regions of the cell further contributes to downstream signalling and adds a previously unknown mechanism underpinning CB1 modulation by ORG27569 , that goes beyond a mere control of receptor affinity for orthosteric ligands.
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Affiliation(s)
- Mariano Stornaiuolo
- Department of Pharmacy, University of Naples "Federico II", via D. Montesano 49, 80131 Naples, Italy
| | - Agostino Bruno
- Department of Pharmacy, University of Naples "Federico II", via D. Montesano 49, 80131 Naples, Italy
| | - Lorenzo Botta
- Department of Pharmacy, University of Naples "Federico II", via D. Montesano 49, 80131 Naples, Italy
| | - Giuseppe La Regina
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Sandro Cosconati
- DiSTABiF, Seconda Università di Napoli, Via Vivaldi 43, 81100 Caserta, Italy
| | - Romano Silvestri
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Luciana Marinelli
- Department of Pharmacy, University of Naples "Federico II", via D. Montesano 49, 80131 Naples, Italy
| | - Ettore Novellino
- Department of Pharmacy, University of Naples "Federico II", via D. Montesano 49, 80131 Naples, Italy
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14
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Cournia Z, Allen TW, Andricioaei I, Antonny B, Baum D, Brannigan G, Buchete NV, Deckman JT, Delemotte L, del Val C, Friedman R, Gkeka P, Hege HC, Hénin J, Kasimova MA, Kolocouris A, Klein ML, Khalid S, Lemieux MJ, Lindow N, Roy M, Selent J, Tarek M, Tofoleanu F, Vanni S, Urban S, Wales DJ, Smith JC, Bondar AN. Membrane Protein Structure, Function, and Dynamics: a Perspective from Experiments and Theory. J Membr Biol 2015; 248:611-40. [PMID: 26063070 PMCID: PMC4515176 DOI: 10.1007/s00232-015-9802-0] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/26/2015] [Indexed: 01/05/2023]
Abstract
Membrane proteins mediate processes that are fundamental for the flourishing of biological cells. Membrane-embedded transporters move ions and larger solutes across membranes; receptors mediate communication between the cell and its environment and membrane-embedded enzymes catalyze chemical reactions. Understanding these mechanisms of action requires knowledge of how the proteins couple to their fluid, hydrated lipid membrane environment. We present here current studies in computational and experimental membrane protein biophysics, and show how they address outstanding challenges in understanding the complex environmental effects on the structure, function, and dynamics of membrane proteins.
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Affiliation(s)
- Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Toby W. Allen
- School of Applied Sciences & Health Innovations Research Institute, RMIT University, GPO Box 2476, Melbourne, Vic, 3001, Australia; and Department of Chemistry, University of California, Davis. Davis, CA 95616, USA
| | - Ioan Andricioaei
- Department of Chemistry, University of California, Irvine, CA 92697
| | - Bruno Antonny
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis and Centre National de la Recherche Scientifique, UMR 7275, 06560 Valbonne, France
| | - Daniel Baum
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Grace Brannigan
- Center for Computational and Integrative Biology and Department of Physics, Rutgers University-Camden, Camden, NJ, USA
| | - Nicolae-Viorel Buchete
- School of Physics and Complex and Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4, Ireland
| | | | - Lucie Delemotte
- Institute of Computational and Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Coral del Val
- Department of Artificial Intelligence, University of Granada, E-18071 Granada, Spain
| | - Ran Friedman
- Linnæus University, Department of Chemistry and Biomedical Sciences & Centre for Biomaterials Chemistry, 391 82 Kalmar, Sweden
| | - Paraskevi Gkeka
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Hans-Christian Hege
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Jérôme Hénin
- Laboratoire de Biochimie Théorique, IBPC and CNRS, Paris, France
| | - Marina A. Kasimova
- Université de Lorraine, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
- Lomonosov Moscow State University, Moscow, 119991, Russian Federation
| | - Antonios Kolocouris
- Faculty of Pharmacy, Department of Pharmaceutical Chemistry, University of Athens, Panepistimioupolis-Zografou, 15771 Athens, Greece
| | - Michael L. Klein
- Institute of Computational and Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Syma Khalid
- Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, UK
| | - M. Joanne Lemieux
- Department of Biochemistry, Faculty of Medicine & Dentistry, Membrane Protein Disease Research Group, and Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Norbert Lindow
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Mahua Roy
- Department of Chemistry, University of California, Irvine
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences, Universitat Pompeu Fabra, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, E-08003 Barcelona, Spain
| | - Mounir Tarek
- Université de Lorraine, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
- CNRS, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
| | - Florentina Tofoleanu
- School of Physics and Complex and Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4, Ireland
| | - Stefano Vanni
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis and Centre National de la Recherche Scientifique, UMR 7275, 06560 Valbonne, France
| | - Sinisa Urban
- Johns Hopkins University School of Medicine, Howard Hughes Medical Institute, Department of Molecular Biology & Genetics, 725 N. Wolfe Street, 507 Preclinical Teaching Building, Baltimore, MD 21205, USA
| | - David J. Wales
- University Chemical Laboratories, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Jeremy C. Smith
- Oak Ridge National Laboratory, PO BOX 2008 MS6309, Oak Ridge, TN 37831-6309, USA
| | - Ana-Nicoleta Bondar
- Theoretical Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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15
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Cao R, Rossetti G, Bauer A, CarIoni P. Binding of the Antagonist Caffeine to the Human Adenosine Receptor hA2AR in Nearly Physiological Conditions. PLoS One 2015; 10:e0126833. [PMID: 25992797 PMCID: PMC4439127 DOI: 10.1371/journal.pone.0126833] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 04/08/2015] [Indexed: 12/27/2022] Open
Abstract
Lipid composition may significantly affect membrane proteins function, yet its impact on the protein structural determinants is not well understood. Here we present a comparative molecular dynamics (MD) study of the human adenosine receptor type 2A (hA(2A)R) in complex with caffeine--a system of high neuro-pharmacological relevance--within different membrane types. These are POPC, mixed POPC/POPE and cholesterol-rich membranes. 0.8-μs MD simulations unambiguously show that the helical folding of the amphipathic helix 8 depends on membrane contents. Most importantly, the distinct cholesterol binding into the cleft between helix 1 and 2 stabilizes a specific caffeine-binding pose against others visited during the simulation. Hence, cholesterol presence (~33%-50% in synaptic membrane in central nervous system), often neglected in X-ray determination of membrane proteins, affects the population of the ligand binding poses. We conclude that including a correct description of neuronal membranes may be very important for computer-aided design of ligands targeting hA(2A)R and possibly other GPCRs.
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Affiliation(s)
- Ruyin Cao
- German Research School for Simulation Sciences (joint venture of RWTH Aachen University and Forschungszentrum Jülich GmbH), D-52425, Jülich, Germany
- Computational Biomedicine, Institute for Advanced Simulation (IAS-5), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
| | - Giulia Rossetti
- German Research School for Simulation Sciences (joint venture of RWTH Aachen University and Forschungszentrum Jülich GmbH), D-52425, Jülich, Germany
- Computational Biomedicine, Institute for Advanced Simulation (IAS-5), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
- Institute of Neuroscience and Medicine (INM-9), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
- Jülich Supercomputing Centre (JSC), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
| | - Andreas Bauer
- Institute of Neuroscience and Medicine (INM-2), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
| | - Paolo CarIoni
- German Research School for Simulation Sciences (joint venture of RWTH Aachen University and Forschungszentrum Jülich GmbH), D-52425, Jülich, Germany
- Computational Biomedicine, Institute for Advanced Simulation (IAS-5), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
- Institute of Neuroscience and Medicine (INM-9), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
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16
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Kawasaki T, Saka T, Mine S, Mizohata E, Inoue T, Matsumura H, Sato T. The N-terminal acidic residue of the cytosolic helix 8 of an odorant receptor is responsible for different response dynamics via G-protein. FEBS Lett 2015; 589:1136-42. [DOI: 10.1016/j.febslet.2015.03.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 03/23/2015] [Accepted: 03/23/2015] [Indexed: 10/23/2022]
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17
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Preti D, Baraldi PG, Saponaro G, Romagnoli R, Aghazadeh Tabrizi M, Baraldi S, Cosconati S, Bruno A, Novellino E, Vincenzi F, Ravani A, Borea PA, Varani K. Design, synthesis, and biological evaluation of novel 2-((2-(4-(substituted)phenylpiperazin-1-yl)ethyl)amino)-5'-N-ethylcarboxamidoadenosines as potent and selective agonists of the A2A adenosine receptor. J Med Chem 2015; 58:3253-67. [PMID: 25780876 DOI: 10.1021/acs.jmedchem.5b00215] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Stimulation of A2A adenosine receptors (AR) promotes anti-inflammatory responses in animal models of allergic rhinitis, asthma, chronic obstructive pulmonary disease, and rheumatic diseases. Herein we describe the results of a research program aimed at identifying potent and selective agonists of the A2AAR as potential anti-inflammatory agents. The recent crystallographic analysis of A2AAR agonists and antagonists in complex with the receptor provided key information on the structural determinants leading to receptor activation or blocking. In light of this, we designed a new series of 2-((4-aryl(alkyl)piperazin-1-yl)alkylamino)-5'-N-ethylcarboxamidoadenosines with high A2AAR affinity, activation potency and selectivity obtained by merging distinctive structural elements of known agonists and antagonists of the investigated target. Docking-based SAR optimization allowed us to identify compound 42 as one of the most potent and selective A2A agonist discovered so far (Ki hA2AAR = 4.8 nM, EC50 hA2AAR = 4.9 nM, Ki hA1AR > 10 000 nM, Ki hA3AR = 1487 nM, EC50 hA2BAR > 10 000 nM).
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Affiliation(s)
- Delia Preti
- †Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Pier Giovanni Baraldi
- †Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Giulia Saponaro
- †Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Romeo Romagnoli
- †Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Mojgan Aghazadeh Tabrizi
- †Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Stefania Baraldi
- †Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Sandro Cosconati
- §DiSTABiF, Seconda Università di Napoli, Via Vivaldi 43, 81100 Caserta, Italy
| | - Agostino Bruno
- ∥Dipartimento di Farmacia, Università di Napoli "Federico II", Via D. Montesano 49, 80131 Napoli, Italy
| | - Ettore Novellino
- ∥Dipartimento di Farmacia, Università di Napoli "Federico II", Via D. Montesano 49, 80131 Napoli, Italy
| | - Fabrizio Vincenzi
- ‡Dipartimento di Scienze Mediche, Sezione di Farmacologia, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Annalisa Ravani
- ‡Dipartimento di Scienze Mediche, Sezione di Farmacologia, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Pier Andrea Borea
- ‡Dipartimento di Scienze Mediche, Sezione di Farmacologia, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Katia Varani
- ‡Dipartimento di Scienze Mediche, Sezione di Farmacologia, Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
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18
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Radchenko EV, Karlov DS, Palyulin VA, Zefirov NS. Molecular modeling of the transmembrane domain of mGluR2 metabotropic glutamate receptor and the binding site of its positive allosteric modulators. DOKL BIOCHEM BIOPHYS 2014; 454:13-6. [PMID: 24633605 DOI: 10.1134/s1607672914010050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Indexed: 11/23/2022]
Affiliation(s)
- E V Radchenko
- Department of Chemistry, Moscow State University, Moscow, 119991, Russia
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19
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Structure of signaling-competent neurotensin receptor 1 obtained by directed evolution in Escherichia coli. Proc Natl Acad Sci U S A 2014; 111:E655-62. [PMID: 24453215 DOI: 10.1073/pnas.1317903111] [Citation(s) in RCA: 168] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Crystallography has advanced our understanding of G protein-coupled receptors, but low expression levels and instability in solution have limited structural insights to very few selected members of this large protein family. Using neurotensin receptor 1 (NTR1) as a proof of principle, we show that two directed evolution technologies that we recently developed have the potential to overcome these problems. We purified three neurotensin-bound NTR1 variants from Escherichia coli and determined their X-ray structures at up to 2.75 Å resolution using vapor diffusion crystallization experiments. A crystallized construct was pharmacologically characterized and exhibited ligand-dependent signaling, internalization, and wild-type-like agonist and antagonist affinities. Our structures are fully consistent with all biochemically defined ligand-contacting residues, and they represent an inactive NTR1 state at the cytosolic side. They exhibit significant differences to a previously determined NTR1 structure (Protein Data Bank ID code 4GRV) in the ligand-binding pocket and by the presence of the amphipathic helix 8. A comparison of helix 8 stability determinants between NTR1 and other crystallized G protein-coupled receptors suggests that the occupancy of the canonical position of the amphipathic helix is reduced to various extents in many receptors, and we have elucidated the sequence determinants for a stable helix 8. Our analysis also provides a structural rationale for the long-known effects of C-terminal palmitoylation reactions on G protein-coupled receptor signaling, receptor maturation, and desensitization.
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20
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Cang X, Yang L, Yang J, Luo C, Zheng M, Yu K, Yang H, Jiang H. Cholesterol-β1AR interaction versus cholesterol-β2AR interaction. Proteins 2013; 82:760-70. [DOI: 10.1002/prot.24456] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Xiaohui Cang
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai 201203 China
- Institute of Genetics; College of Life Science; Zhejiang University; Hangzhou Zhejiang 310058 China
| | - Linlin Yang
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai 201203 China
| | - Jing Yang
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai 201203 China
| | - Cheng Luo
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai 201203 China
| | - Mingyue Zheng
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai 201203 China
| | - Kunqian Yu
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai 201203 China
| | - Huaiyu Yang
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai 201203 China
| | - Hualiang Jiang
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai 201203 China
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21
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Kumari R, Castillo C, Francesconi A. Agonist-dependent signaling by group I metabotropic glutamate receptors is regulated by association with lipid domains. J Biol Chem 2013; 288:32004-19. [PMID: 24045944 DOI: 10.1074/jbc.m113.475863] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group I metabotropic glutamate receptors (mGluRs), mGluR1 and mGluR5, play critical functions in forms of activity-dependent synaptic plasticity and synapse remodeling in physiological and pathological states. Importantly, in animal models of fragile X syndrome, group I mGluR activity is abnormally enhanced, a dysfunction that may partly underlie cognitive deficits in the condition. Lipid rafts are cholesterol- and sphingolipid-enriched membrane domains that are thought to form transient signaling platforms for ligand-activated receptors. Many G protein-coupled receptors, including group I mGluRs, are present in lipid rafts, but the mechanisms underlying recruitment to these membrane domains remain incompletely understood. Here, we show that mGluR1 recruitment to lipid rafts is enhanced by agonist binding and is supported at least in part by an intact cholesterol recognition/interaction amino acid consensus (CRAC) motif in the receptor. Substitutions of critical residues in the motif reduce mGluR1 association with lipid rafts and agonist-induced, mGluR1-dependent activation of extracellular-signal-activated kinase1/2 MAP kinase (ERK-MAPK). We find that alteration of membrane cholesterol content or perturbation of lipid rafts regulates agonist-dependent activation of ERK-MAPK by group I mGluRs, suggesting a potential function for cholesterol as a positive allosteric modulator of receptor function(s). Together, these findings suggest that drugs that alter membrane cholesterol levels or directed to the receptor-cholesterol interface could be employed to modulate abnormal group I mGluR activity in neuropsychiatric conditions, including fragile X syndrome.
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Affiliation(s)
- Ranju Kumari
- From the Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461
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22
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Bishop CV. Progesterone inhibition of oxytocin signaling in endometrium. Front Neurosci 2013; 7:138. [PMID: 23966904 PMCID: PMC3735988 DOI: 10.3389/fnins.2013.00138] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/18/2013] [Indexed: 11/13/2022] Open
Abstract
Expression of the oxytocin receptor (OXTR) in the endometrium of ruminant species is regulated by the ovarian steroids progesterone (P) and estradiol (E). Near the end of the estrous cycle, long-term exposure of endometrial epithelial cells to P results in loss of genomic P receptors (PGRs), leading to an increase in E receptors (ERs). Genomic regulation of the OXTR is mediated via suppression of ER signaling by P. Upon OT binding at the plasma membrane of endometrial cells, a signaling cascade is generated stimulating release of prostaglandin F2α (PGF2α). Transport of PGF2α to the ovary results in release of OT by luteal cells in a positive feedback loop leading to luteal regression. This signaling cascade can be rapidly blocked by exposing endometrial cells to physiologic levels of P. This mini review will focus on the mechanisms by which P may act to block OXTR signaling and the luteolytic cascade in the ruminant endometrium, with special focus on both non-genomic signaling pathways and non-receptor actions of P at the level of the plasma membrane. While this review focuses on ruminant species, non-classical blockage of OXTR signaling may be important for fertility in women.
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Affiliation(s)
- Cecily V Bishop
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University Beaverton, OR, USA
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23
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Structure of the C-terminal region of the Frizzled receptor 1 in detergent micelles. Molecules 2013; 18:8579-90. [PMID: 23881048 PMCID: PMC6269726 DOI: 10.3390/molecules18078579] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 07/18/2013] [Accepted: 07/18/2013] [Indexed: 12/13/2022] Open
Abstract
The C-terminal domains of the Frizzleds (FZDs) contain a short conserved motif (KTXXXW). It has been demonstrated that FZDs interacted with the PDZ domain of the cytoplasmic proteins such as Dishevelled through this motif and mutations in this motif disrupted Wnt/β-catenin signaling. We carried out structural studies for a peptide derived from the C-terminal domain of the FZD1 in different solvents using circular dichroism and solution NMR spectroscopy. Our results showed that this domain was unstructured in an aqueous solution and formed a helical structure in detergent micelles. Fluorescence studies suggested that the tryptophan residue (W630) in the motif interacted with micelles. The solution structure of the peptide in sodium dodecyl sulfate micelles was determined and an amphipathic helix was identified. This helix may have similar function to the helix 8 of other G protein-coupled receptors.
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24
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Yanagawa M, Yamashita T, Shichida Y. Glutamate acts as a partial inverse agonist to metabotropic glutamate receptor with a single amino acid mutation in the transmembrane domain. J Biol Chem 2013; 288:9593-9601. [PMID: 23420844 PMCID: PMC3617263 DOI: 10.1074/jbc.m112.437780] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/15/2013] [Indexed: 11/06/2022] Open
Abstract
Metabotropic glutamate receptor (mGluR), a prototypical family 3 G protein-coupled receptor (GPCR), has served as a model for studying GPCR dimerization, and growing evidence has revealed that a glutamate-induced dimeric rearrangement promotes activation of the receptor. However, structural information of the seven-transmembrane domain is severely limited, in contrast to the well studied family 1 GPCRs including rhodopsins and adrenergic receptors. Homology modeling of mGluR8 transmembrane domain with rhodopsin as a template suggested the presence of a conserved water-mediated hydrogen-bonding network between helices VI and VII, which presumably constrains the receptor in an inactive conformation. We therefore conducted a mutational analysis to assess structural similarities between mGluR and family 1 GPCRs. Mutational experiments confirmed that the disruption of the hydrogen-bonding network by T789Y(6.43) mutation induced high constitutive activity. Unexpectedly, this high constitutive activity was suppressed by glutamate, the natural agonist ligand, indicating that glutamate acts as a partial inverse agonist to this mutant. Fluorescence energy transfer analysis of T789Y(6.43) suggested that the glutamate-induced reduction of the activity originated not from the dimeric rearrangement but from conformational changes within each protomer. Double mutational analysis showed that the specific interaction between Tyr-789(6.43) and Gly-831(7.45) in T789Y(6.43) mutant was important for this phenotype. Therefore, the present study is consistent with the notion that the metabotropic glutamate receptor shares a common activation mechanism with family 1 GPCRs, where rearrangement between helices VI and VII causes the active state formation.
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Affiliation(s)
- Masataka Yanagawa
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Takahiro Yamashita
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshinori Shichida
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
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25
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Kaczor AA, Selent J, Poso A. Structure-based molecular modeling approaches to GPCR oligomerization. Methods Cell Biol 2013; 117:91-104. [PMID: 24143973 DOI: 10.1016/b978-0-12-408143-7.00005-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Classical structure-based drug design techniques using G-protein-coupled receptors (GPCRs) as targets focus nearly exclusively on binding at the orthosteric site of a single receptor. Dimerization and oligomerization of GPCRs, proposed almost 30 years ago, have, however, crucial relevance for drug design. Targeting these complexes selectively or designing small molecules that affect receptor-receptor interactions might provide new opportunities for novel drug discovery. In order to study the mechanisms and dynamics that rule GPCRs oligomerization, it is essential to understand the dynamic process of receptor-receptor association and to identify regions that are suitable for selective drug binding, which may be determined with experimental methods such as Förster resonance energy transfer (FRET) or Bioluminescence resonance energy transfer (BRET) and computational sequence- and structure-based approaches. The aim of this chapter is to provide a comprehensive description of the structure-based molecular modeling methods for studying GPCR dimerization, that is, protein-protein docking, molecular dynamics, normal mode analysis, and electrostatics studies.
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Affiliation(s)
- Agnieszka A Kaczor
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Eastern Finland, Kuopio, Finland; Department of Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, Lublin, Poland
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