1
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Bertalan É, Rodrigues MJ, Schertler GFX, Bondar AN. Graph-based algorithms to dissect long-distance water-mediated H-bond networks for conformational couplings in GPCRs. Br J Pharmacol 2024. [PMID: 38636539 DOI: 10.1111/bph.16387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 02/03/2024] [Accepted: 03/02/2024] [Indexed: 04/20/2024] Open
Abstract
Changes in structure and dynamics elicited by agonist ligand binding at the extracellular side of G protein coupled receptors (GPCRs) must be relayed to the cytoplasmic G protein binding side of the receptors. To decipher the role of water-mediated hydrogen-bond networks in this relay mechanism, we have developed graph-based algorithms and analysis methodologies applicable to datasets of static structures of distinct GPCRs. For a reference dataset of static structures of bovine rhodopsin solved at the same resolution, we show that graph analyses capture the internal protein-water hydrogen-bond network. The extended analyses of static structures of rhodopsins and opioid receptors suggest a relay mechanism whereby inactive receptors have in place much of the internal core hydrogen-bond network required for long-distance relay of structural change, with extensive local H-bond clusters observed in structures solved at high resolution and with internal water molecules.
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Affiliation(s)
- Éva Bertalan
- Physikzentrum, RWTH-Aachen University, Aachen, Germany
| | | | | | - Ana-Nicoleta Bondar
- Forschungszentrum Jülich, Institute of Computational Biomedicine, Jülich, Germany
- Faculty of Physics, University of Bucharest, Măgurele, Romania
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2
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Kapur B, Baldessari F, Lazaratos M, Nar H, Schnapp G, Giorgetti A, Bondar AN. Protons taken hostage: Dynamic H-bond networks of the pH-sensing GPR68. Comput Struct Biotechnol J 2023; 21:4370-4384. [PMID: 37711190 PMCID: PMC10498176 DOI: 10.1016/j.csbj.2023.08.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 08/30/2023] [Accepted: 08/30/2023] [Indexed: 09/16/2023] Open
Abstract
Proton-sensing G Protein Coupled Receptors (GPCRs) sense changes in the extracellular pH to effect cell signaling for cellular homeostasis. They tend to be overexpressed in solid tumors associated with acidic extracellular pH, and are of direct interest as drug targets. How proton-sensing GPCRs sense extracellular acidification and activate upon protonation change is important to understand, because it may guide the design of therapeutics. Lack of publicly available experimental structures make it challenging to discriminate between conflicting mechanisms proposed for proton-binding, as main roles have been assigned to either an extracellular histidine cluster or to an internal carboxylic triad. Here we present a protocol to derive and evaluate structural models of the proton-sensing GPR68. This approach integrates state-of-the-art homology modeling with microsecond-timescale atomistic simulations, and with a detailed assessment of the compatibility of the structural models with known structural features of class A GPCRs. To decipher structural elements of potential interest for protonation-coupled conformational changes of GPR68, we used the best-compatible model as a starting point for independent atomistic simulations of GPR68 with different protonation states, and graph computations to characterize the response of GPR68 to changes in protonation. We found that GPR68 hosts an extended hydrogen-bond network that inter-connects the extracellular histidine cluster to the internal carboxylic triad, and which can even reach groups at the cytoplasmic G-protein binding site. Taken together, results suggest that GPR68 relies on dynamic, hydrogen-bond networks to inter-connect extracellular and internal proton-binding sites, and to elicit conformational changes at the cytoplasmic G-protein binding site.
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Affiliation(s)
- Bhav Kapur
- Boehringer-Ingelheim Pharma GmbH & Co. KG, Birkendorfer Straße 65, 88397 Biberach an der Riß, Germany
- Christian-Albrechts-University of Kiel, 24118 Kiel, Germany
| | | | - Michalis Lazaratos
- Department of Physics, Theoretical Molecular Biophysics Group, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Herbert Nar
- Boehringer-Ingelheim Pharma GmbH & Co. KG, Birkendorfer Straße 65, 88397 Biberach an der Riß, Germany
| | - Gisela Schnapp
- Boehringer-Ingelheim Pharma GmbH & Co. KG, Birkendorfer Straße 65, 88397 Biberach an der Riß, Germany
| | - Alejandro Giorgetti
- University of Verona, Department of Biotechnology, 37134 Verona, Italy
- Forschungszentrum Jülich, Institute for Neuroscience and Medicine and Institute for Advanced Simulations (IAS-5/INM-9), Computational Biomedicine, Wilhelm-Johnen Straße, 52525 Jülich, Germany
| | - Ana-Nicoleta Bondar
- Forschungszentrum Jülich, Institute for Neuroscience and Medicine and Institute for Advanced Simulations (IAS-5/INM-9), Computational Biomedicine, Wilhelm-Johnen Straße, 52525 Jülich, Germany
- University of Bucharest, Faculty of Physics, Str. Atomiştilor 405, 077125 Bucharest-Măgurele, Romania
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Grinberg M, Burton J, Pang KC, Zimering MB. Neuroprotective Effects of a Serotonin Receptor Peptide Following Sham vs. Mild Traumatic Brain Injury in the Zucker Rat. ENDOCRINOLOGY, DIABETES AND METABOLISM JOURNAL 2023; 7:1-9. [PMID: 37560759 PMCID: PMC10411128 DOI: 10.31038/edmj.2023731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Aims Accelerated cognitive decline frequently complicates traumatic brain injury. Obesity and type 2 diabetes mellitus drive peripheral inflammation which may accelerate traumatic brain injury-associated neurodegeneration. The Zucker rat harbors G-protein coupled receptor agonist IgG autoantibodies and in vitro neurotoxicity caused by these autoantibodies was prevented by a novel synthetic fragment of the serotonin 2A receptor. The aim of the present study was to test whether genetic obesity manifested in Zucker diabetic fatty rat is associated with greater spatial memory impairment before and after mild traumatic brain injury compared to Zucker lean rats. Furthermore, we investigated whether these neurodegenerative complications can be lessened by administration of a novel putative neuroprotective peptide comprised of a fragment of the second extracellular loop of the serotonin 2A receptor. Methods Age-matched lean and fatty diabetic Zucker rats were tested in the Morris water maze (spatial memory) prior to receiving a sham-injury or lateral fluid percussion (LFP) mild traumatic brain injury. Behavioral testing was repeated at 1-week, 1-month, and 3-month intervals following injury. A synthetic peptide consisting of a portion of the 5-hydroxytryptamine (serotonin) 2A receptor (2 mg/kg) (vehicle, or an inactive scrambled version of the peptide (2 mg/kg)) was administered via intraperitoneal route every other day for 7 days after sham or LFP injury to lean rats or 7 days before and after sham or LFP injury to fatty rats. Results Mild traumatic brain injury impaired recall of spatial memory in fatty and lean rats. Zucker fatty rats subjected to sham-injury or mild TBI experienced a significantly greater longitudinal decline in recall of spatial memory compared to lean Zucker rats. A synthetic peptide fragment of the 5-hydroxytryptamine 2A receptor significantly enhanced acquisition of spatial learning and it appeared to strengthen recall of spatial learning (one-week) after sham injury in Zucker rats. Conclusions These data suggest that the Zucker diabetic fatty rat is a suitable animal model to investigate the role of metabolic factor(s) in accelerated cognitive decline. A novel synthetic peptide comprised of a fragment of the second extracellular loop of the human serotonin 2A receptor appeared to have neuroprotective effects on both acquisition and recall of spatial memory in subsets of Zucker rats, with relatively greater benefit in sham-injured, lean Zucker rats.
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Affiliation(s)
- Mihal Grinberg
- Veterans Affairs New Jersey Healthcare System, East Orange, New Jersey, USA
| | - Julia Burton
- Veterans Affairs New Jersey Healthcare System, East Orange, New Jersey, USA
| | - Kevin Ch Pang
- Veterans Affairs New Jersey Healthcare System, East Orange, New Jersey, USA
| | - Mark B Zimering
- Veterans Affairs New Jersey Healthcare System, East Orange, New Jersey, USA
- Endocrinology, Rutgers/Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
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4
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Abstract
Rhodopsin is the photoreceptor in human rod cells responsible for dim-light vision. The visual receptors are part of the large superfamily of G protein-coupled receptors (GPCRs) that mediate signal transduction in response to diverse diffusible ligands. The high level of sequence conservation within the transmembrane helices of the visual receptors and the family A GPCRs has long been considered evidence for a common pathway for signal transduction. I review recent studies that reveal a comprehensive mechanism for how light absorption by the retinylidene chromophore drives rhodopsin activation and highlight those features of the mechanism that are conserved across the ligand-activated GPCRs.
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Affiliation(s)
- Steven O Smith
- Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, New York, USA;
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5
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Nicoli A, Haag F, Marcinek P, He R, Kreißl J, Stein J, Marchetto A, Dunkel A, Hofmann T, Krautwurst D, Di Pizio A. Modeling the Orthosteric Binding Site of the G Protein-Coupled Odorant Receptor OR5K1. J Chem Inf Model 2023; 63:2014-2029. [PMID: 36696962 PMCID: PMC10091413 DOI: 10.1021/acs.jcim.2c00752] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
With approximately 400 encoding genes in humans, odorant receptors (ORs) are the largest subfamily of class A G protein-coupled receptors (GPCRs). Despite its high relevance and representation, the odorant-GPCRome is structurally poorly characterized: no experimental structures are available, and the low sequence identity of ORs to experimentally solved GPCRs is a significant challenge for their modeling. Moreover, the receptive range of most ORs is unknown. The odorant receptor OR5K1 was recently and comprehensively characterized in terms of cognate agonists. Here, we report two additional agonists and functional data of the most potent compound on two mutants, L1043.32 and L2556.51. Experimental data was used to guide the investigation of the binding modes of OR5K1 ligands into the orthosteric binding site using structural information from AI-driven modeling, as recently released in the AlphaFold Protein Structure Database, and from homology modeling. Induced-fit docking simulations were used to sample the binding site conformational space for ensemble docking. Mutagenesis data guided side chain residue sampling and model selection. We obtained models that could better rationalize the different activity of active (agonist) versus inactive molecules with respect to starting models and also capture differences in activity related to minor structural differences. Therefore, we provide a model refinement protocol that can be applied to model the orthosteric binding site of ORs as well as that of GPCRs with low sequence identity to available templates.
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Affiliation(s)
- Alessandro Nicoli
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Franziska Haag
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Patrick Marcinek
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Ruiming He
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany.,Department of Chemistry, Technical University of Munich, 85748 Garching, Germany
| | - Johanna Kreißl
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Jörg Stein
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Alessandro Marchetto
- Computational Biomedicine, Institute for Advanced Simulations (IAS)-5/Institute for Neuroscience and Medicine (INM)-9, Forschungszentrum Jülich, 52428 Jülich, Germany.,Department of Biology, Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen University, 52074 Aachen, Germany
| | - Andreas Dunkel
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Thomas Hofmann
- Chair of Food Chemistry and Molecular Sensory Science, Technical University of Munich, 85354 Freising, Germany
| | - Dietmar Krautwurst
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
| | - Antonella Di Pizio
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, 85354 Freising, Germany
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de Grip WJ, Ganapathy S. Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering. Front Chem 2022; 10:879609. [PMID: 35815212 PMCID: PMC9257189 DOI: 10.3389/fchem.2022.879609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/16/2022] [Indexed: 01/17/2023] Open
Abstract
The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal. In the 1970s a microbial counterpart of this species was discovered in an archaeon, being a membrane protein also harbouring retinal as a chromophore, and named bacteriorhodopsin. Since their discovery a photogenic panorama unfolded, where up to date new members and subspecies with a variety of light-driven functionality have been added to this family. The animal branch, meanwhile categorized as type-2 rhodopsins, turned out to form a large subclass in the superfamily of G protein-coupled receptors and are essential to multiple elements of light-dependent animal sensory physiology. The microbial branch, the type-1 rhodopsins, largely function as light-driven ion pumps or channels, but also contain sensory-active and enzyme-sustaining subspecies. In this review we will follow the development of this exciting membrane protein panorama in a representative number of highlights and will present a prospect of their extraordinary future potential.
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Affiliation(s)
- Willem J. de Grip
- Leiden Institute of Chemistry, Department of Biophysical Organic Chemistry, Leiden University, Leiden, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Srividya Ganapathy
- Department of Imaging Physics, Delft University of Technology, Netherlands
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7
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Malik F, Li Z. Is there a common allosteric binding site for G-protein coupled receptors? J Comput Aided Mol Des 2022; 36:405-413. [PMID: 35507106 PMCID: PMC10150935 DOI: 10.1007/s10822-022-00454-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/19/2022] [Indexed: 11/30/2022]
Abstract
Targeting the allosteric sites on G-protein coupled receptors (GPCRs) for drug discovery is attracting increased interest. Given a GPCR target, identifying the allosteric binding sites in it remains a challenge. Previous works from our and other labs suggest the intracellular region below the middle of the transmembrane (TM) domain that spatially overlaps with the G-protein binding site could contain a common allosteric site for all GPCRs. We performed several bioinformatics analyses on this site for more than 100 representative human GPCR structures. Results of the studies confirmed that the proposed region contains an allosteric site that is druggable for 89% of the GPCRs and is not 100% identical between a GPCR and its most similar homolog for 94% of the GPCRs. The physico-chemical properties and amino acid composition of this site vary among and within GPCR classes. Since this proposed region occupies the space existing in all GPCRs of known structure, it could represent a common host of an allosteric site for all GPCRs that can be targeted for structure-based allosteric drug design.
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Affiliation(s)
- Faisal Malik
- Department of Chemistry & Biochemistry, University of the Sciences in Philadelphia, Philadelphia, PA, 19104, USA
| | - Zhijun Li
- Department of Chemistry & Biochemistry, University of the Sciences in Philadelphia, Philadelphia, PA, 19104, USA.
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8
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Bueschbell B, Manga P, Schiedel AC. The Many Faces of G Protein-Coupled Receptor 143, an Atypical Intracellular Receptor. Front Mol Biosci 2022; 9:873777. [PMID: 35495622 PMCID: PMC9039016 DOI: 10.3389/fmolb.2022.873777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/10/2022] [Indexed: 12/24/2022] Open
Abstract
GPCRs transform extracellular stimuli into a physiological response by activating an intracellular signaling cascade initiated via binding to G proteins. Orphan G protein-coupled receptors (GPCRs) hold the potential to pave the way for development of new, innovative therapeutic strategies. In this review we will introduce G protein-coupled receptor 143 (GPR143), an enigmatic receptor in terms of classification within the GPCR superfamily and localization. GPR143 has not been assigned to any of the GPCR families due to the lack of common structural motifs. Hence we will describe the most important motifs of classes A and B and compare them to the protein sequence of GPR143. While a precise function for the receptor has yet to be determined, the protein is expressed abundantly in pigment producing cells. Many GPR143 mutations cause X-linked Ocular Albinism Type 1 (OA1, Nettleship-Falls OA), which results in hypopigmentation of the eyes and loss of visual acuity due to disrupted visual system development and function. In pigment cells of the skin, loss of functional GPR143 results in abnormally large melanosomes (organelles in which pigment is produced). Studies have shown that the receptor is localized internally, including at the melanosomal membrane, where it may function to regulate melanosome size and/or facilitate protein trafficking to the melanosome through the endolysosomal system. Numerous additional roles have been proposed for GPR143 in determining cancer predisposition, regulation of blood pressure, development of macular degeneration and signaling in the brain, which we will briefly describe as well as potential ligands that have been identified. Furthermore, GPR143 is a promiscuous receptor that has been shown to interact with multiple other melanosomal proteins and GPCRs, which strongly suggests that this orphan receptor is likely involved in many different physiological actions.
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Affiliation(s)
- Beatriz Bueschbell
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Prashiela Manga
- Ronald O. Perelman Department of Dermatology, Grossman School of Medicine, New York University, New York City, NY, United States
| | - Anke C. Schiedel
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, Bonn, Germany
- *Correspondence: Anke C. Schiedel,
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9
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Chandler B, Todd L, Smith SO. Magic angle spinning NMR of G protein-coupled receptors. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 128:25-43. [PMID: 35282868 PMCID: PMC10718405 DOI: 10.1016/j.pnmrs.2021.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 06/14/2023]
Abstract
G protein-coupled receptors (GPCRs) have a simple seven transmembrane helix architecture which has evolved to recognize a diverse number of chemical signals. The more than 800 GPCRs encoded in the human genome function as receptors for vision, smell and taste, and mediate key physiological processes. Consequently, these receptors are a major target for pharmaceuticals. Protein crystallography and electron cryo-microscopy have provided high resolution structures of many GPCRs in both active and inactive conformations. However, these structures have not sparked a surge in rational drug design, in part because GPCRs are inherently dynamic and the structural changes induced by ligand or drug binding to stabilize inactive or active conformations are often subtle rearrangements in packing or hydrogen-bonding interactions. NMR spectroscopy provides a sensitive probe of local structure and dynamics at specific sites within these receptors as well as global changes in receptor structure and dynamics. These methods can also capture intermediate states and conformations with low populations that provide insights into the activation pathways. We review the use of solid-state magic angle spinning NMR to address the structure and activation mechanisms of GPCRs. The focus is on the large and diverse class A family of receptors. We highlight three specific class A GPCRs in order to illustrate how solid-state, as well as solution-state, NMR spectroscopy can answer questions in the field involving how different GPCR classes and subfamilies are activated by their associated ligands, and how small molecule drugs can modulate GPCR activation.
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Affiliation(s)
- Bianca Chandler
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States.
| | - Lauren Todd
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States.
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States.
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10
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Smith SO. Deconstructing the transmembrane core of class A G protein-coupled receptors. Trends Biochem Sci 2021; 46:1017-1029. [PMID: 34538727 PMCID: PMC8595765 DOI: 10.1016/j.tibs.2021.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/19/2021] [Accepted: 08/23/2021] [Indexed: 01/14/2023]
Abstract
Class A G protein-coupled receptors have evolved to recognize ligands ranging from small-molecule odorants to proteins. Although they are among the most diverse membrane receptors in eukaryotic organisms, they possess a highly conserved core within their seven-transmembrane helix framework. The conservation of the transmembrane core has led to the idea of a common mechanism by which ligand binding is coupled to the outward rotation of helix H6, the hallmark of an active receptor. Nevertheless, there is still no consensus on the mechanism of coupling or on the roles of specific residues within the core. Recent insights from crystallography and NMR spectroscopy provide a way to decompose the core into its essential structural and functional elements that shed new light on this important region.
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Affiliation(s)
- Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.
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11
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Fernandez-Gonzalez P, Mas-Sanchez A, Garriga P. Polyphenols and Visual Health: Potential Effects on Degenerative Retinal Diseases. Molecules 2021; 26:3407. [PMID: 34199888 PMCID: PMC8200069 DOI: 10.3390/molecules26113407] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/26/2022] Open
Abstract
Dietary polyphenols are a group of natural compounds that have been proposed to have beneficial effects on human health. They were first known for their antioxidant properties, but several studies over the years have shown that these compounds can exert protective effects against chronic diseases. Nonetheless, the mechanisms underlying these potential benefits are still uncertain and contradictory effects have been reported. In this review, we analyze the potential effects of polyphenol compounds on some visual diseases, with a special focus on retinal degenerative diseases. Current effective therapies for the treatment of such retinal diseases are lacking and new strategies need to be developed. For this reason, there is currently a renewed interest in finding novel ligands (or known ligands with previously unexpected features) that could bind to retinal photoreceptors and modulate their molecular properties. Some polyphenols, especially flavonoids (e.g., quercetin and tannic acid), could attenuate light-induced receptor damage and promote visual health benefits. Recent evidence suggests that certain flavonoids could help stabilize the correctly folded conformation of the visual photoreceptor protein rhodopsin and offset the deleterious effect of retinitis pigmentosa mutations. In this regard, certain polyphenols, like the flavonoids mentioned before, have been shown to improve the stability, expression, regeneration and folding of rhodopsin mutants in experimental in vitro studies. Moreover, these compounds appear to improve the integration of the receptor into the cell membrane while acting against oxidative stress at the same time. We anticipate that polyphenol compounds can be used to target visual photoreceptor proteins, such as rhodopsin, in a way that has only been recently proposed and that these can be used in novel approaches for the treatment of retinal degenerative diseases like retinitis pigmentosa; however, studies in this field are limited and further research is needed in order to properly characterize the effects of these compounds on retinal degenerative diseases through the proposed mechanisms.
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Affiliation(s)
| | | | - Pere Garriga
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d’Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, 08222 Terrassa, Spain; (P.F.-G.); (A.M.-S.)
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12
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Molecular evolution of a collage of cholesterol interaction motifs in transmembrane helix V of the serotonin 1A receptor. Chem Phys Lipids 2020; 232:104955. [PMID: 32846149 DOI: 10.1016/j.chemphyslip.2020.104955] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/08/2020] [Accepted: 08/16/2020] [Indexed: 12/20/2022]
Abstract
The human serotonin1A receptor is a representative member of the superfamily of G protein-coupled receptors (GPCRs) and an important drug target for neurological disorders. Using a combination of biochemical, biophysical and molecular dynamics simulation approaches, we and others have shown that membrane cholesterol modulates the organization, dynamics and function of vertebrate serotonin1A receptors. Previous studies have shown that the cytoplasmic portion of transmembrane helix V (TM V) and the extramembraneous intracellular loop 3 are critical for G-protein coupling, phosphorylation and desensitization of the receptor. We have recently resolved a collage of putative cholesterol interaction motifs from the amino acid sequence overlapping this region. In this paper, we explore the sequence plasticity of this fragment that may have adapted to altered membrane lipidome, after vertebrates evolved from primordial invertebrates. Since invertebrates have lower levels of membrane cholesterol relative to vertebrates, we compared TM V sequence fragments from invertebrate serotonin1 receptors with vertebrate orthologs to infer the sequence plasticity in TM V. We report that the average number of cholesterol interaction motifs in TM V for diverse phyla represents an increasing trend that could mirror vertebrate evolution from primordial invertebrates. By statistical modeling, we propose that the collage of cholesterol interaction motifs in TM V of the human serotonin1A receptor may have evolved from rudimentary collages, reminiscent of primordial invertebrate orthologs. Taken together, we propose that a repertoire of cholesterol-philic nonsynonymous substitutions may have enhanced collage complexity in TM V during vertebrate evolution.
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13
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Pope AL, Sanchez-Reyes OB, South K, Zaitseva E, Ziliox M, Vogel R, Reeves PJ, Smith SO. A Conserved Proline Hinge Mediates Helix Dynamics and Activation of Rhodopsin. Structure 2020; 28:1004-1013.e4. [PMID: 32470317 DOI: 10.1016/j.str.2020.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/24/2020] [Accepted: 05/11/2020] [Indexed: 01/05/2023]
Abstract
Despite high-resolution crystal structures of both inactive and active G protein-coupled receptors (GPCRs), it is still not known how ligands trigger the large structural change on the intracellular side of the receptor since the conformational changes that occur within the extracellular ligand-binding region upon activation are subtle. Here, we use solid-state NMR and Fourier transform infrared spectroscopy on rhodopsin to show that Trp2656.48 within the CWxP motif on transmembrane helix H6 constrains a proline hinge in the inactive state, suggesting that activation results in unraveling of the H6 backbone within this motif, a local change in dynamics that allows helix H6 to swing outward. Notably, Tyr3017.48 within activation switch 2 appears to mimic the negative allosteric sodium ion found in other family A GPCRs, a finding that is broadly relevant to the mechanism of receptor activation.
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Affiliation(s)
- Andreyah L Pope
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Omar B Sanchez-Reyes
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Kieron South
- School of Life Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, UK
| | - Ekaterina Zaitseva
- Biophysics Section, Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University, Freiburg, Hermann Herder Strasse, 79104 Freiburg, Germany
| | - Martine Ziliox
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Reiner Vogel
- Biophysics Section, Institute of Molecular Medicine and Cell Research, Albert-Ludwigs-University, Freiburg, Hermann Herder Strasse, 79104 Freiburg, Germany
| | - Philip J Reeves
- School of Life Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, UK
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.
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Ikegami K, de March CA, Nagai MH, Ghosh S, Do M, Sharma R, Bruguera ES, Lu YE, Fukutani Y, Vaidehi N, Yohda M, Matsunami H. Structural instability and divergence from conserved residues underlie intracellular retention of mammalian odorant receptors. Proc Natl Acad Sci U S A 2020; 117:2957-2967. [PMID: 31974307 PMCID: PMC7022149 DOI: 10.1073/pnas.1915520117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Mammalian odorant receptors are a diverse and rapidly evolving set of G protein-coupled receptors expressed in olfactory cilia membranes. Most odorant receptors show little to no cell surface expression in nonolfactory cells due to endoplasmic reticulum retention, which has slowed down biochemical studies. Here we provide evidence that structural instability and divergence from conserved residues of individual odorant receptors underlie intracellular retention using a combination of large-scale screening of odorant receptors cell surface expression in heterologous cells, point mutations, structural modeling, and machine learning techniques. We demonstrate the importance of conserved residues by synthesizing consensus odorant receptors that show high levels of cell surface expression similar to conventional G protein-coupled receptors. Furthermore, we associate in silico structural instability with poor cell surface expression using molecular dynamics simulations. We propose an enhanced evolutionary capacitance of olfactory sensory neurons that enable the functional expression of odorant receptors with cryptic mutations.
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Affiliation(s)
- Kentaro Ikegami
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
| | - Claire A de March
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Maira H Nagai
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
- Department of Biochemistry, Universidade de Sao Paulo, Sao Paulo, 05508-000, Brazil
| | - Soumadwip Ghosh
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA 91010
| | - Matthew Do
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Ruchira Sharma
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Elise S Bruguera
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Yueyang Eric Lu
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Yosuke Fukutani
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA 91010
| | - Masafumi Yohda
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
| | - Hiroaki Matsunami
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710;
- Department of Neurobiology, Duke Institute for Brain Sciences, Duke University, Durham, NC 27710
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15
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Singh KD, Unal H, Desnoyer R, Karnik SS. Mechanism of Hormone Peptide Activation of a GPCR: Angiotensin II Activated State of AT 1R Initiated by van der Waals Attraction. J Chem Inf Model 2019; 59:373-385. [PMID: 30608150 DOI: 10.1021/acs.jcim.8b00583] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We present a succession of structural changes involved in hormone peptide activation of a prototypical GPCR. Microsecond molecular dynamics simulation generated conformational ensembles reveal propagation of structural changes through key "microswitches" within human AT1R bound to native hormone. The endocrine octa-peptide angiotensin II (AngII) activates AT1R signaling in our bodies which maintains physiological blood pressure, electrolyte balance, and cardiovascular homeostasis. Excessive AT1R activation is associated with pathogenesis of hypertension and cardiovascular diseases which are treated by sartan drugs. The mechanism of AT1R inhibition by sartans has been elucidated by 2.8 Å X-ray structures, mutagenesis, and computational analyses. Yet, the mechanism of AT1R activation by AngII is unclear. The current study delineates an activation scheme initiated by AngII binding. A van der Waals "grasp" interaction between Phe8AngII with Ile2887.39 in AT1R induced mechanical strain pulling Tyr2927.43 and breakage of critical interhelical H-bonds, first between Tyr2927.43 and Val1083.32 and second between Asn1113.35 and Asn2957.46. Subsequently changes are observed in conserved microswitches DRYTM3, Yx7K(R)TM5, CWxPTM6, and NPxxYTM7 in AT1R. Activating the microswitches in the intracellular region of AT1R may trigger formation of the G-protein binding pocket as well as exposure of helix-8 to cytoplasm. Thus, the active-like conformation of AT1R is initiated by the van der Waals interaction of Phe8AngII with Ile2887.39, followed by systematic reorganization of critical interhelical H-bonds and activation of microswitches.
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Affiliation(s)
- Khuraijam Dhanachandra Singh
- Department of Molecular Cardiology, Lerner Research Institute , Cleveland Clinic Foundation , Cleveland , Ohio 44195 , United States
| | - Hamiyet Unal
- Department of Molecular Cardiology, Lerner Research Institute , Cleveland Clinic Foundation , Cleveland , Ohio 44195 , United States
| | - Russell Desnoyer
- Department of Molecular Cardiology, Lerner Research Institute , Cleveland Clinic Foundation , Cleveland , Ohio 44195 , United States
| | - Sadashiva S Karnik
- Department of Molecular Cardiology, Lerner Research Institute , Cleveland Clinic Foundation , Cleveland , Ohio 44195 , United States
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16
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Garelja ML, Walker CA, Siow A, Yang SH, Harris PWR, Brimble MA, Watkins HA, Gingell JJ, Hay DL. Receptor Activity Modifying Proteins Have Limited Effects on the Class B G Protein-Coupled Receptor Calcitonin Receptor-Like Receptor Stalk. Biochemistry 2018; 57:1410-1422. [PMID: 29388762 DOI: 10.1021/acs.biochem.7b01180] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The calcitonin receptor-like receptor (CLR) is a class B G protein-coupled receptor (GPCR) that forms the basis of three pharmacologically distinct receptors, the calcitonin gene-related peptide (CGRP) receptor, and two adrenomedullin (AM) receptors. These three receptors are created by CLR interacting with three receptor activity-modifying proteins (RAMPs). Class B GPCRs have an N-terminal extracellular domain (ECD) and transmembrane bundle that are both important for binding endogenous ligands. These two domains are joined together by a stretch of amino acids that is referred to as the "stalk". Studies of other class B GPCRs suggest that the stalk may act as hinge, allowing the ECD to adopt multiple conformations. It is unclear what the role of the stalk is within CLR and whether RAMPs can influence its function. Therefore, this study investigated the role of this region using an alanine scan. Effects of mutations were measured with all three RAMPs through cell surface expression, cAMP production and, in select cases, radioligand binding and total cell expression assays. Most mutants did not affect expression or cAMP signaling. CLR C127A, N140A, F142A, and L144A impaired cell surface expression with all three RAMPs. T125A decreased the potency of all peptides at all receptors. N128A, V135A, and L139A showed ligand-dependent effects. While the stalk appears to play a role in CLR function, the effect of RAMPs on this region seems limited, in contrast to their effects on the structure of CLR in other receptor regions.
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Affiliation(s)
- Michael L Garelja
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand
| | - Christina A Walker
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand
| | - Andrew Siow
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand
| | - Sung H Yang
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand
| | - Paul W R Harris
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand
| | - Margaret A Brimble
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand.,School of Chemical Sciences, The University of Auckland , 23 Symonds Street, Auckland 1010, New Zealand
| | - Harriet A Watkins
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand
| | - Joseph J Gingell
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand
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17
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Athanasiou D, Aguila M, Bellingham J, Li W, McCulley C, Reeves PJ, Cheetham ME. The molecular and cellular basis of rhodopsin retinitis pigmentosa reveals potential strategies for therapy. Prog Retin Eye Res 2018; 62:1-23. [PMID: 29042326 PMCID: PMC5779616 DOI: 10.1016/j.preteyeres.2017.10.002] [Citation(s) in RCA: 213] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/03/2017] [Accepted: 10/13/2017] [Indexed: 12/12/2022]
Abstract
Inherited mutations in the rod visual pigment, rhodopsin, cause the degenerative blinding condition, retinitis pigmentosa (RP). Over 150 different mutations in rhodopsin have been identified and, collectively, they are the most common cause of autosomal dominant RP (adRP). Mutations in rhodopsin are also associated with dominant congenital stationary night blindness (adCSNB) and, less frequently, recessive RP (arRP). Recessive RP is usually associated with loss of rhodopsin function, whereas the dominant conditions are a consequence of gain of function and/or dominant negative activity. The in-depth characterisation of many rhodopsin mutations has revealed that there are distinct consequences on the protein structure and function associated with different mutations. Here we categorise rhodopsin mutations into seven discrete classes; with defects ranging from misfolding and disruption of proteostasis, through mislocalisation and disrupted intracellular traffic to instability and altered function. Rhodopsin adRP offers a unique paradigm to understand how disturbances in photoreceptor homeostasis can lead to neuronal cell death. Furthermore, a wide range of therapies have been tested in rhodopsin RP, from gene therapy and gene editing to pharmacological interventions. The understanding of the disease mechanisms associated with rhodopsin RP and the development of targeted therapies offer the potential of treatment for this currently untreatable neurodegeneration.
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Affiliation(s)
| | - Monica Aguila
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - James Bellingham
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Wenwen Li
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Caroline McCulley
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Philip J Reeves
- School of Biological Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, UK.
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