1
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Hong JD, Palczewski K. A short story on how chromophore is hydrolyzed from rhodopsin for recycling. Bioessays 2023; 45:e2300068. [PMID: 37454357 PMCID: PMC10614701 DOI: 10.1002/bies.202300068] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/24/2023] [Accepted: 05/30/2023] [Indexed: 07/18/2023]
Abstract
The photocycle of visual opsins is essential to maintain the light sensitivity of the retina. The early physical observations of the rhodopsin photocycle by Böll and Kühne in the 1870s inspired over a century's worth of investigations on rhodopsin biochemistry. A single photon isomerizes the Schiff-base linked 11-cis-retinylidene chromophore of rhodopsin, converting it to the all-trans agonist to elicit phototransduction through photoactivated rhodopsin (Rho*). Schiff base hydrolysis of the agonist is a key step in the photocycle, not only diminishing ongoing phototransduction but also allowing for entry and binding of fresh 11-cis chromophore to regenerate the rhodopsin pigment and maintain light sensitivity. Many challenges have been encountered in measuring the rate of this hydrolysis, but recent advancements have facilitated studies of the hydrolysis within the native membrane environment of rhodopsin. These techniques can now be applied to study hydrolysis of agonist in other opsin proteins that mediate phototransduction or chromophore turnover. In this review, we discuss the progress that has been made in characterizing the rhodopsin photocycle and the journey to characterize the hydrolysis of its all-trans-retinylidene agonist.
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Affiliation(s)
- John D. Hong
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
- Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
- Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, USA
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697, USA
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2
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Hofmann KP, Lamb TD. Rhodopsin, light-sensor of vision. Prog Retin Eye Res 2023; 93:101116. [PMID: 36273969 DOI: 10.1016/j.preteyeres.2022.101116] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 11/06/2022]
Abstract
The light sensor of vertebrate scotopic (low-light) vision, rhodopsin, is a G-protein-coupled receptor comprising a polypeptide chain with bound chromophore, 11-cis-retinal, that exhibits remarkable physicochemical properties. This photopigment is extremely stable in the dark, yet its chromophore isomerises upon photon absorption with 70% efficiency, enabling the activation of its G-protein, transducin, with high efficiency. Rhodopsin's photochemical and biochemical activities occur over very different time-scales: the energy of retinaldehyde's excited state is stored in <1 ps in retinal-protein interactions, but it takes milliseconds for the catalytically active state to form, and many tens of minutes for the resting state to be restored. In this review, we describe the properties of rhodopsin and its role in rod phototransduction. We first introduce rhodopsin's gross structural features, its evolution, and the basic mechanisms of its activation. We then discuss light absorption and spectral sensitivity, photoreceptor electrical responses that result from the activity of individual rhodopsin molecules, and recovery of rhodopsin and the visual system from intense bleaching exposures. We then provide a detailed examination of rhodopsin's molecular structure and function, first in its dark state, and then in the active Meta states that govern its interactions with transducin, rhodopsin kinase and arrestin. While it is clear that rhodopsin's molecular properties are exquisitely honed for phototransduction, from starlight to dawn/dusk intensity levels, our understanding of how its molecular interactions determine the properties of scotopic vision remains incomplete. We describe potential future directions of research, and outline several major problems that remain to be solved.
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Affiliation(s)
- Klaus Peter Hofmann
- Institut für Medizinische Physik und Biophysik (CC2), Charité, and, Zentrum für Biophysik und Bioinformatik, Humboldt-Unversität zu Berlin, Berlin, 10117, Germany.
| | - Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia.
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3
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Casajuana-Martin N, Navarro G, Gonzalez A, Llinas del Torrent C, Gómez-Autet M, Quintana García A, Franco R, Pardo L. A Single Point Mutation Blocks the Entrance of Ligands to the Cannabinoid CB 2 Receptor via the Lipid Bilayer. J Chem Inf Model 2022; 62:5771-5779. [PMID: 36302505 PMCID: PMC9709915 DOI: 10.1021/acs.jcim.2c00865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Molecular dynamic (MD) simulations have become a common tool to study the pathway of ligand entry to the orthosteric binding site of G protein-coupled receptors. Here, we have combined MD simulations and site-directed mutagenesis to study the binding process of the potent JWH-133 agonist to the cannabinoid CB2 receptor (CB2R). In CB2R, the N-terminus and extracellular loop 2 fold over the ligand binding pocket, blocking access to the binding cavity from the extracellular environment. We, thus, hypothesized that the binding pathway is a multistage process consisting of the hydrophobic ligand diffusing in the lipid bilayer to contact a lipid-facing vestibule, from which the ligand enters an allosteric site inside the transmembrane bundle through a tunnel formed between TMs 1 and 7 and finally moving from the allosteric to the orthosteric binding cavity. This pathway was experimentally validated by the Ala2827.36Phe mutation that blocks the entrance of the ligand, as JWH-133 was not able to decrease the forskolin-induced cAMP levels in cells expressing the mutant receptor. This proposed ligand entry pathway defines transient binding sites that are potential cavities for the design of synthetic modulators.
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Affiliation(s)
- Nil Casajuana-Martin
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Gemma Navarro
- Department
of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, Universitat de Barcelona, 08028 Barcelona, Spain,Centro
de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28031 Madrid, Spain
| | - Angel Gonzalez
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Claudia Llinas del Torrent
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Marc Gómez-Autet
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Aleix Quintana García
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Rafael Franco
- Centro
de Investigación en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, 28031 Madrid, Spain,Department
of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Leonardo Pardo
- Laboratory
of Computational Medicine, Biostatistics Unit, Faculty of Medicine, Universitat Autònoma Barcelona, 08193 Bellaterra, Barcelona, Spain,E-mail:
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4
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Obi P, Natesan S. Membrane Lipids Are an Integral Part of Transmembrane Allosteric Sites in GPCRs: A Case Study of Cannabinoid CB1 Receptor Bound to a Negative Allosteric Modulator, ORG27569, and Analogs. J Med Chem 2022; 65:12240-12255. [PMID: 36066412 PMCID: PMC9512009 DOI: 10.1021/acs.jmedchem.2c00946] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Indexed: 11/28/2022]
Abstract
A growing number of G-protein-coupled receptor (GPCR) structures reveal novel transmembrane lipid-exposed allosteric sites. Ligands must first partition into the surrounding membrane and take lipid paths to these sites. Remarkably, a significant part of the bound ligands appears exposed to the membrane lipids. The experimental structures do not usually account for the surrounding lipids, and their apparent contribution to ligand access and binding is often overlooked and poorly understood. Using classical and enhanced molecular dynamics simulations, we show that membrane lipids are critical in the access and binding of ORG27569 and its analogs at the transmembrane site of cannabinoid CB1 receptor. The observed differences in the binding affinity and cooperativity arise from the functional groups that interact primarily with lipids. Our results demonstrate the significance of incorporating membrane lipids as an integral component of transmembrane sites for accurate characterization, binding-affinity calculations, and lead optimization in drug discovery.
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Affiliation(s)
- Peter Obi
- College of Pharmacy and Pharmaceutical
Sciences, Washington State University, Spokane, Washington 99202, United States
| | - Senthil Natesan
- College of Pharmacy and Pharmaceutical
Sciences, Washington State University, Spokane, Washington 99202, United States
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5
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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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6
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Tian H, Gunnison KM, Kazmi MA, Sakmar TP, Huber T. FRET sensors reveal the retinal entry pathway in the G protein-coupled receptor rhodopsin. iScience 2022; 25:104060. [PMID: 35355518 PMCID: PMC8958324 DOI: 10.1016/j.isci.2022.104060] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 01/11/2022] [Accepted: 03/04/2022] [Indexed: 11/26/2022] Open
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7
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Sutcliffe KJ, Corey RA, Alhosan N, Cavallo D, Groom S, Santiago M, Bailey C, Charlton SJ, Sessions RB, Henderson G, Kelly E. Interaction With the Lipid Membrane Influences Fentanyl Pharmacology. ADVANCES IN DRUG AND ALCOHOL RESEARCH 2022; 2. [PMID: 35909438 PMCID: PMC7613138 DOI: 10.3389/adar.2022.10280] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Overdose deaths from fentanyl have reached epidemic proportions in the USA and are increasing worldwide. Fentanyl is a potent opioid agonist that is less well reversed by naloxone than morphine. Due to fentanyl’s high lipophilicity and elongated structure we hypothesised that its unusual pharmacology may be explained by its interactions with the lipid membrane on route to binding to the μ-opioid receptor (MOPr). Through coarse-grained molecular dynamics simulations, electrophysiological recordings and cell signalling assays, we determined how fentanyl and morphine access the orthosteric pocket of MOPr. Morphine accesses MOPr via the aqueous pathway; first binding to an extracellular vestibule, then diffusing into the orthosteric pocket. In contrast, fentanyl may take a novel route; first partitioning into the membrane, before accessing the orthosteric site by diffusing through a ligand-induced gap between the transmembrane helices. In electrophysiological recordings fentanyl-induced currents returned after washout, suggesting fentanyl deposits in the lipid membrane. However, mutation of residues forming the potential MOPr transmembrane access site did not alter fentanyl’s pharmacological profile in vitro. A high local concentration of fentanyl in the lipid membrane, possibly in combination with a novel lipophilic binding route, may explain the high potency and lower susceptibility of fentanyl to reversal by naloxone.
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Affiliation(s)
- Katy J Sutcliffe
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Robin A Corey
- Department of Biochemistry, Medical Sciences Division, University of Oxford, Oxford, United Kingdom
| | - Norah Alhosan
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Damiana Cavallo
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Sam Groom
- Department of Pharmacy and Pharmacology, Faculty of Science, University of Bath, Bath, United Kingdom
| | - Marina Santiago
- Macquarie Medical School, Macquarie University, Sydney, NSW, Australia
| | - Chris Bailey
- Department of Pharmacy and Pharmacology, Faculty of Science, University of Bath, Bath, United Kingdom
| | - Steven J Charlton
- Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Richard B Sessions
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Graeme Henderson
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Eamonn Kelly
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
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8
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Xu Z, Guo L, Qian X, Yu C, Li S, Zhu C, Ma X, Li H, Zhu G, Zhou H, Dai W, Li Q, Gao X. Two entry tunnels in mouse TAAR9 suggest the possibility of multi-entry tunnels in olfactory receptors. Sci Rep 2022; 12:2691. [PMID: 35177711 PMCID: PMC8854740 DOI: 10.1038/s41598-022-06591-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 01/24/2022] [Indexed: 12/16/2022] Open
Abstract
Orthosteric binding sites of olfactory receptors have been well understood for ligand-receptor interactions. However, a lack of explanation for subtle differences in ligand profile of olfactory receptors even with similar orthosteric binding sites promotes more exploration into the entry tunnels of the receptors. An important question regarding entry tunnels is the number of entry tunnels, which was previously believed to be one. Here, we used TAAR9 that recognizes important biogenic amines such as cadaverine, spermine, and spermidine as a model for entry tunnel study. We identified two entry tunnels in TAAR9 and described the residues that form the tunnels. In addition, we found two vestibular binding pockets, each located in one tunnel. We further confirmed the function of two tunnels through site-directed mutagenesis. Our study challenged the existing views regarding the number of entry tunnels in the subfamily of olfactory receptors and demonstrated the possible mechanism how the entry tunnels function in odorant recognition.
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Affiliation(s)
- ZhengRong Xu
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.,Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Department of Anatomy and Physiology, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health in Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - LingNa Guo
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Department of Anatomy and Physiology, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health in Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.,Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - XiaoYun Qian
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - ChenJie Yu
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - ShengJu Li
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Department of Anatomy and Physiology, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health in Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - ChengWen Zhu
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - XiaoFeng Ma
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Hui Li
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - GuangJie Zhu
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Han Zhou
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - WenXuan Dai
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China. .,Department of Anatomy and Physiology, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health in Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Qian Li
- Center for Brain Science, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China. .,Department of Anatomy and Physiology, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health in Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China. .,Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai, 201210, China.
| | - Xia Gao
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China. .,Research Institute of Otolaryngology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.
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9
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New insights into the molecular mechanism of rhodopsin retinitis pigmentosa from the biochemical and functional characterization of G90V, Y102H and I307N mutations. Cell Mol Life Sci 2022; 79:58. [PMID: 34997336 PMCID: PMC8741697 DOI: 10.1007/s00018-021-04086-0] [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: 07/26/2021] [Revised: 11/29/2021] [Accepted: 12/09/2021] [Indexed: 11/17/2022]
Abstract
Mutations in the photoreceptor protein rhodopsin are known as one of the leading causes of retinal degeneration in humans. Two rhodopsin mutations, Y102H and I307N, obtained in chemically mutagenized mice, are currently the subject of increased interest as relevant models for studying the process of retinal degeneration in humans. Here, we report on the biochemical and functional characterization of the structural and functional alterations of these two rhodopsin mutants and we compare them with the G90V mutant previously analyzed, as a basis for a better understanding of in vivo studies. This mechanistic knowledge is fundamental to use it for developing novel therapeutic approaches for the treatment of inherited retinal degeneration in retinitis pigmentosa. We find that Y102H and I307N mutations affect the inactive–active equilibrium of the receptor. In this regard, the mutations reduce the stability of the inactive conformation but increase the stability of the active conformation. Furthermore, the initial rate of the functional activation of transducin, by the I307N mutant is reduced, but its kinetic profile shows an unusual increase with time suggesting a profound effect on the signal transduction process. This latter effect can be associated with a change in the flexibility of helix 7 and an indirect effect of the mutation on helix 8 and the C-terminal tail of rhodopsin, whose potential role in the functional activation of the receptor has been usually underestimated. In the case of the Y102H mutant, the observed changes can be associated with conformational alterations affecting the folding of the rhodopsin intradiscal domain, and its presumed involvement in the retinal binding process by the receptor.
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10
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Krishna Deepak RNV, Verma RK, Hartono YD, Yew WS, Fan H. Recent Advances in Structure, Function, and Pharmacology of Class A Lipid GPCRs: Opportunities and Challenges for Drug Discovery. Pharmaceuticals (Basel) 2021; 15:12. [PMID: 35056070 PMCID: PMC8779880 DOI: 10.3390/ph15010012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/17/2021] [Accepted: 12/17/2021] [Indexed: 01/01/2023] Open
Abstract
Great progress has been made over the past decade in understanding the structural, functional, and pharmacological diversity of lipid GPCRs. From the first determination of the crystal structure of bovine rhodopsin in 2000, much progress has been made in the field of GPCR structural biology. The extraordinary progress in structural biology and pharmacology of GPCRs, coupled with rapid advances in computational approaches to study receptor dynamics and receptor-ligand interactions, has broadened our comprehension of the structural and functional facets of the receptor family members and has helped usher in a modern age of structure-based drug design and development. First, we provide a primer on lipid mediators and lipid GPCRs and their role in physiology and diseases as well as their value as drug targets. Second, we summarize the current advancements in the understanding of structural features of lipid GPCRs, such as the structural variation of their extracellular domains, diversity of their orthosteric and allosteric ligand binding sites, and molecular mechanisms of ligand binding. Third, we close by collating the emerging paradigms and opportunities in targeting lipid GPCRs, including a brief discussion on current strategies, challenges, and the future outlook.
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Affiliation(s)
- R. N. V. Krishna Deepak
- Bioinformatics Institute, A*STAR, 30 Biopolis Street, Matrix #07-01, Singapore 138671, Singapore; (R.K.V.); (Y.D.H.)
| | - Ravi Kumar Verma
- Bioinformatics Institute, A*STAR, 30 Biopolis Street, Matrix #07-01, Singapore 138671, Singapore; (R.K.V.); (Y.D.H.)
| | - Yossa Dwi Hartono
- Bioinformatics Institute, A*STAR, 30 Biopolis Street, Matrix #07-01, Singapore 138671, Singapore; (R.K.V.); (Y.D.H.)
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive, Singapore 117599, Singapore;
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore 117597, Singapore
| | - Wen Shan Yew
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive, Singapore 117599, Singapore;
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore 117597, Singapore
| | - Hao Fan
- Bioinformatics Institute, A*STAR, 30 Biopolis Street, Matrix #07-01, Singapore 138671, Singapore; (R.K.V.); (Y.D.H.)
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive, Singapore 117599, Singapore;
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11
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Guérin DMA, Digilio A, Branda MM. Dimeric Rhodopsin R135L Mutant-Transducin-like Complex Sheds Light on Retinitis Pigmentosa Misfunctions. J Phys Chem B 2021; 125:12958-12971. [PMID: 34793169 DOI: 10.1021/acs.jpcb.1c06348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rhodopsin (RHO) is a light-sensitive pigment in the retina and the main prototypical protein of the G-protein-coupled receptor (GCPR) family. After receiving a light stimulus, RHO and its cofactor retinylidene undergo a series of structural changes that initiate an intricate transduction mechanism. Along with RHO, other partner proteins play key roles in the signaling pathway. These include transducin, a GTPase, kinases that phosphorylate RHO, and arrestin (Arr), which ultimately stops the signaling process and promotes RHO regeneration. A large number of RHO genetic mutations may lead to very severe retinal dysfunction and eventually to impaired dark adaptation disease called autosomal dominant retinitis pigmentosa (adRP). In this study, we used molecular dynamics (MD) simulations to evaluate the different behaviors of the dimeric form of wild-type RHO (WT dRHO) and its mutant at position 135 of arginine to leucine (dR135L), both in the free (noncomplexed) and in complex with the transducin-like protein (Gtl). Gtl is a heterotrimeric model composed of a mixture of human and bovine G proteins. Our calculations allow us to explain how the mutation causes structural changes in the RHO dimer and how this can affect the signal that transducin generates when it is bound to RHO. Moreover, the structural modifications induced by the R135L mutation can also account for other misfunctions observed in the up- and downstream signaling pathways. The mechanism of these dysfunctions, together with the transducin activity reduction, provides structure-based explanations of the impairment of some key processes that lead to adRP.
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Affiliation(s)
- Diego M A Guérin
- Department of Biochemistry and Molecular Biology, University of the Basque Country (EHU) and Instituto Biofisika (CSIC, UPV/EHU), Barrio Sarriena S/N, 48940 Leioa, Vizcaya, Spain
| | - Ayelen Digilio
- Department of Physics, National University of San Luis (UNSL), Av. Ejército de los Andes 950, 5700 San Luis, Argentina
| | - María Marta Branda
- Institute of Applied Physics (CONICET-UNSL), Av. Ejercito de los Andes 950, 5700 San Luis, Argentina
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12
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Ito RK, Harada S, Tabata R, Watanabe K. Molecular evolution and convergence of the rhodopsin gene in Gymnogobius, a goby group having diverged into coastal to freshwater habitats. J Evol Biol 2021; 35:333-346. [PMID: 34689368 DOI: 10.1111/jeb.13955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/03/2021] [Accepted: 10/12/2021] [Indexed: 12/20/2022]
Abstract
Adaptive evolution of vision-related genes has been frequently observed in the process of invasion of new environments in a wide range of animal taxa. The typical example is that of the molecular evolution of rhodopsin associated with habitat changes in aquatic animals. However, few studies have investigated rhodopsin evolution during adaptive radiation across various habitats. In the present study, we examined the link between molecular evolutionary patterns in the rhodopsin gene and macroscopic habitat changes in Gymnogobius species (Gobiidae), which have adaptively radiated to diverse aquatic habitats including the sea, brackish waters, rivers and lakes. Analysis of amino acid substitutions in rhodopsin in the phylogenetic framework revealed convergent substitutions in 4-5 amino acids in three groups (four species), including two spectral tuning amino acid sites known to change rhodopsin's absorption wavelength. Positive selection was detected in the basal branches of each of these three groups, suggesting adaptive molecular convergence of rhodopsin. However, no significant correlation was observed between amino acid substitutions and the species' habitat changes, suggesting molecular adaptation to some unidentified micro-ecological environments. Taken together, these results emphasize the importance of considering not only macroscopic habitats but also micro-ecological environments when elucidating the driving forces of adaptive evolution of the visual system.
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Affiliation(s)
- Ryosuke K Ito
- Division of Biological Sciences, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto City, Japan
| | - Shigeo Harada
- Resource Management Division, Fisheries Bureau, Agriculture, Forestry and Fisheries Department, Wakayama Prefectural Government, Wakayama City, Japan
| | | | - Katsutoshi Watanabe
- Division of Biological Sciences, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto City, Japan
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13
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Róg T, Girych M, Bunker A. Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design. Pharmaceuticals (Basel) 2021; 14:1062. [PMID: 34681286 PMCID: PMC8537670 DOI: 10.3390/ph14101062] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 11/17/2022] Open
Abstract
We review the use of molecular dynamics (MD) simulation as a drug design tool in the context of the role that the lipid membrane can play in drug action, i.e., the interaction between candidate drug molecules and lipid membranes. In the standard "lock and key" paradigm, only the interaction between the drug and a specific active site of a specific protein is considered; the environment in which the drug acts is, from a biophysical perspective, far more complex than this. The possible mechanisms though which a drug can be designed to tinker with physiological processes are significantly broader than merely fitting to a single active site of a single protein. In this paper, we focus on the role of the lipid membrane, arguably the most important element outside the proteins themselves, as a case study. We discuss work that has been carried out, using MD simulation, concerning the transfection of drugs through membranes that act as biological barriers in the path of the drugs, the behavior of drug molecules within membranes, how their collective behavior can affect the structure and properties of the membrane and, finally, the role lipid membranes, to which the vast majority of drug target proteins are associated, can play in mediating the interaction between drug and target protein. This review paper is the second in a two-part series covering MD simulation as a tool in pharmaceutical research; both are designed as pedagogical review papers aimed at both pharmaceutical scientists interested in exploring how the tool of MD simulation can be applied to their research and computational scientists interested in exploring the possibility of a pharmaceutical context for their research.
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Affiliation(s)
- Tomasz Róg
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Mykhailo Girych
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Alex Bunker
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 Helsinki, Finland;
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14
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Szlenk CT, Gc JB, Natesan S. Membrane-facilitated receptor access and binding mechanisms of long-acting β2-adrenergic receptor (β2-AR) agonists. Mol Pharmacol 2021; 100:406-427. [PMID: 34334369 DOI: 10.1124/molpharm.121.000285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/20/2021] [Indexed: 11/22/2022] Open
Abstract
The drugs salmeterol, formoterol, and salbutamol constitute the frontline treatment for asthma and other chronic pulmonary diseases. These drugs activate the β2-adrenergic receptors (β2-AR), a class A G-protein-coupled receptor (GPCR) and differ significantly in their clinical onset and duration of actions. According to the "microkinetic model," the long duration of action of salmeterol and formoterol compared to salbutamol were attributed, at least in part, to their high lipophilicity and increased local concentrations in the membrane near the receptor. However, the structural and molecular bases of how the lipophilic drugs reach the binding site of the receptor from the surrounding membrane remain unknown. Using a variety of classical and enhanced molecular dynamics simulation techniques, we investigated the membrane partitioning characteristics, binding, and unbinding mechanisms of the ligands. The obtained results offer remarkable insight into the functional role of membrane lipids in the ligand association process. Strikingly, salmeterol entered the binding site from the bilayer through transmembrane helices 1 and 7. The entry was preceded by membrane-facilitated rearrangement and presentation of its phenyl-alkoxy-alkyl tail as a passkey to an access route gated by F193, a residue known critical for salmeterol's affinity. Formoterol's access is through the aqueous path shared by other β2-AR agents. We observed a novel secondary path for salbutamol that is distinct from its primary route. Our study offers a mechanistic description for the membrane-facilitated access and binding of ligands to β2-AR and establishes a groundwork for recognizing membrane lipids as an integral component in the molecular recognition process. Significance Statement The cell membrane's functional role behind the duration of action of long-acting β2-adrenergic receptor (β2-AR) agonists such as salmeterol has been a subject of debate for a long time. We investigated the binding and unbinding mechanisms of the three commonly used β2-AR agonists, salmeterol, formoterol, and salbutamol, using advanced simulation techniques. The obtained results offer unprecedented insights into the active role of membrane lipids in facilitating access and binding of the ligands, affecting the molecular recognition process and their pharmacology.
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Affiliation(s)
| | | | - Senthil Natesan
- Pharmaceutical Sciences, Washington State University, United States
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15
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Membrane binding properties of the C-terminal segment of retinol dehydrogenase 8. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183605. [PMID: 33766534 DOI: 10.1016/j.bbamem.2021.183605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/01/2021] [Accepted: 03/12/2021] [Indexed: 12/18/2022]
Abstract
Light absorption by rhodopsin leads to the release of all-trans retinal (ATRal) in the lipid phase of photoreceptor disc membranes. Retinol dehydrogenase 8 (RDH8) then reduces ATRal into all-trans retinol, which is the first step of the visual cycle. The membrane binding of RDH8 has been postulated to be mediated by one or more palmitoylated cysteines located in its C-terminus. Different peptide variants of the C-terminus of RDH8 were thus used to obtain information on the mechanism of membrane binding of this enzyme. Steady-state and time-resolved fluorescence measurements were performed using short and long C-terminal segments of bovine RDH8, comprising one or two tryptophan residues. The data demonstrate that the amphipathic alpha helical structure of the first portion of the C-terminus of RDH8 strongly contributes to its membrane binding, which is also favored by palmitoylation of at least one of the cysteines located in the last portion of the C-terminus.
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16
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Accelerated evolution and positive selection of rhodopsin in Tibetan loaches living in high altitude. Int J Biol Macromol 2020; 165:2598-2606. [PMID: 33470199 DOI: 10.1016/j.ijbiomac.2020.10.151] [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: 07/31/2020] [Revised: 10/16/2020] [Accepted: 10/19/2020] [Indexed: 11/22/2022]
Abstract
Rhodopsin (RH1), the temperature-sensitive visual pigment, attained cold adaptation by functional trade-offs between protein stability and activity. Recent studies suggested convergent selection pressures drove cold adaptation of rhodopsin in high altitude catfishes through nonparallel molecular mechanisms. Here, we tested whether the similar shift occurred in RH1 of Tibetan loaches on the Qinghai-Tibet Plateau (QTP) by investigating the molecular evolution and potential effect on function of RH1. We sequenced RH1 from 27 Triplophysa species, and four lowland loaches and combined these data with published sequences. Tests using a series of models of molecular evolution resulted in strong evidence for accelerated evolution and positive selection in Triplophysa RH1. Three positively selected sites were near key functional domains modulating nonspectral properties of rhodopsin, substitutions of which were likely to compensate for cold-induced decrease in rhodopsin kinetics in cold environments. Moreover, although accelerated evolutionary rates in Tibetan loaches was convergent with those in high altitude catfishes, the sites under positive selection were nonoverlapping. Our findings provide evidence for convergent shift in selection pressures of RH1 in high altitude fish during the ecological transition to cold environment of the QTP.
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17
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Rodríguez-Espigares I, Torrens-Fontanals M, Tiemann JKS, Aranda-García D, Ramírez-Anguita JM, Stepniewski TM, Worp N, Varela-Rial A, Morales-Pastor A, Medel-Lacruz B, Pándy-Szekeres G, Mayol E, Giorgino T, Carlsson J, Deupi X, Filipek S, Filizola M, Gómez-Tamayo JC, Gonzalez A, Gutiérrez-de-Terán H, Jiménez-Rosés M, Jespers W, Kapla J, Khelashvili G, Kolb P, Latek D, Marti-Solano M, Matricon P, Matsoukas MT, Miszta P, Olivella M, Perez-Benito L, Provasi D, Ríos S, R Torrecillas I, Sallander J, Sztyler A, Vasile S, Weinstein H, Zachariae U, Hildebrand PW, De Fabritiis G, Sanz F, Gloriam DE, Cordomi A, Guixà-González R, Selent J. GPCRmd uncovers the dynamics of the 3D-GPCRome. Nat Methods 2020; 17:777-787. [PMID: 32661425 DOI: 10.1038/s41592-020-0884-y] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 05/29/2020] [Indexed: 11/08/2022]
Abstract
G-protein-coupled receptors (GPCRs) are involved in numerous physiological processes and are the most frequent targets of approved drugs. The explosion in the number of new three-dimensional (3D) molecular structures of GPCRs (3D-GPCRome) over the last decade has greatly advanced the mechanistic understanding and drug design opportunities for this protein family. Molecular dynamics (MD) simulations have become a widely established technique for exploring the conformational landscape of proteins at an atomic level. However, the analysis and visualization of MD simulations require efficient storage resources and specialized software. Here we present GPCRmd (http://gpcrmd.org/), an online platform that incorporates web-based visualization capabilities as well as a comprehensive and user-friendly analysis toolbox that allows scientists from different disciplines to visualize, analyze and share GPCR MD data. GPCRmd originates from a community-driven effort to create an open, interactive and standardized database of GPCR MD simulations.
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Affiliation(s)
- Ismael Rodríguez-Espigares
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Mariona Torrens-Fontanals
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Johanna K S Tiemann
- Institute of Medical Physics and Biophysics, Charite University Medicine Berlin, Berlin, Germany
- Institute of Medical Physics and Biophysics, Medical University Leipzig, Leipzig, Sachsen, Germany
| | - David Aranda-García
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Juan Manuel Ramírez-Anguita
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Tomasz Maciej Stepniewski
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Nathalie Worp
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Alejandro Varela-Rial
- Computational Science Laboratory, Universitat Pompeu Fabra, Barcelona Biomedical Research Park, Barcelona, Spain
- Acellera, Barcelona, Spain
| | - Adrián Morales-Pastor
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Brian Medel-Lacruz
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Gáspár Pándy-Szekeres
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Eduardo Mayol
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Toni Giorgino
- Biophysics Institute, National Research Council of Italy, Milan, Italy
- Department of Biosciences, University of Milan, Milan, Italy
| | - Jens Carlsson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Xavier Deupi
- Laboratory of Biomolecular Research, Paul Scherrer Institute (PSI), Villigen PSI, Switzerland
- Condensed Matter Theory Group, PSI, Villigen PSI, Switzerland
| | - Slawomir Filipek
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - José Carlos Gómez-Tamayo
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Angel Gonzalez
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Hugo Gutiérrez-de-Terán
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Uppsala, Sweden
| | - Mireia Jiménez-Rosés
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Willem Jespers
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Uppsala, Sweden
| | - Jon Kapla
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA
- Institute for Computational Biomedicine, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Peter Kolb
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Dorota Latek
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Maria Marti-Solano
- Department of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Pierre Matricon
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Minos-Timotheos Matsoukas
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Department of Pharmacy, University of Patras, Patras, Greece
| | - Przemyslaw Miszta
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Mireia Olivella
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Laura Perez-Benito
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Davide Provasi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Santiago Ríos
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Iván R Torrecillas
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Jessica Sallander
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Uppsala, Sweden
| | - Agnieszka Sztyler
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Silvana Vasile
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Uppsala, Sweden
| | - Harel Weinstein
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA
- Institute for Computational Biomedicine, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK
- Physics, School of Science and Engineering, University of Dundee, Dundee, UK
| | - Peter W Hildebrand
- Institute of Medical Physics and Biophysics, Charite University Medicine Berlin, Berlin, Germany
- Institute of Medical Physics and Biophysics, Medical University Leipzig, Leipzig, Sachsen, Germany
- Berlin Institute of Health, Berlin, Germany
| | - Gianni De Fabritiis
- Computational Science Laboratory, Universitat Pompeu Fabra, Barcelona Biomedical Research Park, Barcelona, Spain
- Acellera, Barcelona, Spain
| | - Ferran Sanz
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - David E Gloriam
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Arnau Cordomi
- Laboratori de Medicina Computacional, Unitat de Bioestadistica, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Ramon Guixà-González
- Laboratory of Biomolecular Research, Paul Scherrer Institute (PSI), Villigen PSI, Switzerland.
- Condensed Matter Theory Group, PSI, Villigen PSI, Switzerland.
| | - Jana Selent
- Research Programme on Biomedical Informatics, Hospital del Mar Medical Research Institute-Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain.
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18
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Lolicato F, Juhola H, Zak A, Postila PA, Saukko A, Rissanen S, Enkavi G, Vattulainen I, Kepczynski M, Róg T. Membrane-Dependent Binding and Entry Mechanism of Dopamine into Its Receptor. ACS Chem Neurosci 2020; 11:1914-1924. [PMID: 32538079 PMCID: PMC7735663 DOI: 10.1021/acschemneuro.9b00656] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Synaptic neurotransmission has recently been proposed to function via either a membrane-independent or a membrane-dependent mechanism, depending on the neurotransmitter type. In the membrane-dependent mechanism, amphipathic neurotransmitters first partition to the lipid headgroup region and then diffuse along the membrane plane to their membrane-buried receptors. However, to date, this mechanism has not been demonstrated for any neurotransmitter-receptor complex. Here, we combined isothermal calorimetry measurements with a diverse set of molecular dynamics simulation methods to investigate the partitioning of an amphipathic neurotransmitter (dopamine) and the mechanism of its entry into the ligand-binding site. Our results show that the binding of dopamine to its receptor is consistent with the membrane-dependent binding and entry mechanism. Both experimental and simulation results showed that dopamine favors binding to lipid membranes especially in the headgroup region. Moreover, our simulations revealed a ligand-entry pathway from the membrane to the binding site. This pathway passes through a lateral gate between transmembrane alpha-helices 5 and 6 on the membrane-facing side of the protein. All in all, our results demonstrate that dopamine binds to its receptor by a membrane-dependent mechanism, and this is complemented by the more traditional binding mechanism directly through the aqueous phase. The results suggest that the membrane-dependent mechanism is common in other synaptic receptors, too.
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Affiliation(s)
- Fabio Lolicato
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Biochemistry Center, Heidelberg University, D-69120 Heidelberg, Germany
| | - Hanna Juhola
- Computational Physics Laboratory, Tampere University, FI-33100 Tampere, Finland
| | - Agata Zak
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Pekka A. Postila
- Institute of Biomedicine, Faculty of Medicine, University of Turku, FI-20014 Turku, Finland
| | - Annina Saukko
- Department of Applied Physics, University of Eastern Finland, P.O.B. 1627, FI-70211 Kuopio, Finland
- Department of Medical Physics, Turku University Hospital, FI-20520 Turku, Finland
| | - Sami Rissanen
- Computational Physics Laboratory, Tampere University, FI-33100 Tampere, Finland
| | - Giray Enkavi
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational Physics Laboratory, Tampere University, FI-33100 Tampere, Finland
- MEMPHYS − Center for Biomembrane Physics
| | - Mariusz Kepczynski
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Tomasz Róg
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
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19
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The Hydrophobic Ligands Entry and Exit from the GPCR Binding Site-SMD and SuMD Simulations. Molecules 2020; 25:molecules25081930. [PMID: 32326322 PMCID: PMC7221835 DOI: 10.3390/molecules25081930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/10/2020] [Accepted: 04/17/2020] [Indexed: 12/17/2022] Open
Abstract
Most G protein-coupled receptors that bind the hydrophobic ligands (lipid receptors and steroid receptors) belong to the most populated class A (rhodopsin-like) of these receptors. Typical examples of lipid receptors are: rhodopsin, cannabinoid (CB), sphingosine-1-phosphate (S1P) and lysophosphatidic (LPA) receptors. The hydrophobic ligands access the receptor binding site from the lipid bilayer not only because of their low solubility in water but also because of a large N-terminal domain plug preventing access to the orthosteric binding site from the extracellular milieu. In order to identify the most probable ligand exit pathway from lipid receptors CB1, S1P1 and LPA1 orthosteric binding sites we performed at least three repeats of steered molecular dynamics simulations in which ligands were pulled in various directions. For specific ligands being agonists, the supervised molecular dynamics approach was used to simulate the ligand entry events to the inactive receptor structures. For all investigated receptors the ligand entry/exit pathway goes through the gate between transmembrane helices TM1 and TM7, however, in some cases it combined with a direction toward water milieu.
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20
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Coussa RG, Basali D, Maeda A, DeBenedictis M, Traboulsi EI. Sector retinitis pigmentosa: Report of ten cases and a review of the literature. Mol Vis 2019; 25:869-889. [PMID: 31908405 PMCID: PMC6937219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Accepted: 12/28/2019] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To describe the genotypes and phenotypes of ten patients with sector retinitis pigmentosa (RP). We also review previously reported mutations associated with sector RP and provide a discussion of possible underlying pathophysiological mechanisms. METHODS Patients underwent detailed ophthalmologic examinations, fundus photography, fundus autofluorescence (FAF) imaging, spectral-domain optical coherence tomography (SD-OCT), as well as visual field and electroretinographic testing. All patients underwent genetic testing to identify the molecular etiology of their disease. RESULTS A total of ten patients were studied. Among these patients, nine had mutations in RHO (c.677T>C; p.Leu226Pro (novel), c.68C>A; p.Pro23His, c.808A>C; p.Ser270Arg, c.44A>G; p.Asn15Ser, and c.325G>A; p.Gly109Arg), and one patient had a mutation in RPGR (c.3092_3093delAG; p.Glu1031Glyfs*47). All patients with missense mutations in RHO had visual acuities (VAs) better than 20/30 and showed a retained foveal ellipsoid zone and overlying retinal structures. The patient with the c.3092_3093delAG deletion in RPGR had VA of 20/60 oculus dexter (OD) and 20/400 oculus sinister (OS), as well as significant foveal thinning and contour atrophy. All patients showed pigmentary changes, or marked atrophy along the inferior arcades, or both. This pattern of degeneration corresponded to hypo- and hyperFAF and superior visual defects. CONCLUSIONS Sector RP is an uncommon form of RP in which only one or two retinal quadrants display clinical pathological signs. The great majority of cases result from mutations in RHO. The present data confirmed previously reported phenotypic manifestations of sector RP. Inferior retinal quadrants are possibly more severely affected due to greater light exposure.
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Affiliation(s)
- Razek Georges Coussa
- Center for Genetic Eye Diseases, Cole Eye Institute, Cleveland Clinic, Cleveland, OH
| | - Diana Basali
- Center for Genetic Eye Diseases, Cole Eye Institute, Cleveland Clinic, Cleveland, OH
| | - Akiko Maeda
- Department of Ophthalmology & Visual Sciences, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Meghan DeBenedictis
- Center for Genetic Eye Diseases, Cole Eye Institute, Cleveland Clinic, Cleveland, OH
| | - Elias I. Traboulsi
- Center for Genetic Eye Diseases, Cole Eye Institute, Cleveland Clinic, Cleveland, OH
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21
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Kiriakidi S, Chatzigiannis C, Papaemmanouil C, Tzakos AG, Mavromoustakos T. Exploring the role of the membrane bilayer in the recognition of candesartan by its GPCR AT1 receptor. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183142. [PMID: 31830465 DOI: 10.1016/j.bbamem.2019.183142] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 11/13/2019] [Accepted: 11/28/2019] [Indexed: 01/20/2023]
Abstract
Cardiovascular diseases and hypertension in particular are major health risks worldwide and the improvement on their treatment will be beneficial for the human health. AT1R antagonists belong to the sartans family that targets the renin-angiotensin aldosterone system (RAAS) through blocking the hormone angiotensin II to exert its detrimental effects in pathological states. As a consequence, they are beneficial to treat hypertension, diabetes related kidney failure and hyperaemic episodes. Long unbiased Molecular Dynamics (MD) simulations are performed in order to explore candesartan's possible 2D and 3D diffusion mechanisms towards AT1R receptor. 3D diffusion mechanism is referred to the direct binding of the AT1 antagonist candesartan to the AT1R 3D structure (PDB ID: 4YAY). 2D diffusion mechanism involves first, the incorporation of candesartan in the bilayer core and then its localization on the AT1R binding cavity, through a diffusion mechanism. The obtained results indicate that membranes interact significantly with the neutral form of candesartan, which is indeed approaching the receptors' active site through diffusion via the lipids. On the other hand, the deprotonated form of the drug is interacting with AT1R's extracellular loop and fails to enter the membrane, pointing out the importance of the pH microenvironment around the receptor. To validate the calculated diffusion coefficients of the drug in the lipid bilayers 2D DOSY NMR experiments were recorded and they were in good agreement. Information on the impact that has the interaction of candesartan with the membrane is very important for the rationally design and development of potent ARBs. Thus, its conformational features as well as its localization in the membrane core have to be thoroughly explored.
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Affiliation(s)
- Sofia Kiriakidi
- National and Kapodistrian University of Athens, Department of Chemistry, Athens, Greece
| | - Christos Chatzigiannis
- University of Ioannina, Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece
| | - Christina Papaemmanouil
- University of Ioannina, Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece
| | - Andreas G Tzakos
- University of Ioannina, Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece
| | - Thomas Mavromoustakos
- National and Kapodistrian University of Athens, Department of Chemistry, Athens, Greece.
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22
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Abstract
The evolutionary process that occurs when a species colonizes a new environment provides an opportunity to explore the mechanisms underlying genetic adaptation, which is essential knowledge for understanding evolution and the maintenance of biodiversity. Atlantic herring has an estimated total breeding stock of about 1 trillion (1012) and has colonized the brackish Baltic Sea within the last 10,000 y. Minute genetic differentiation between Atlantic and Baltic herring populations at selectively neutral loci combined with this rapid adaptation to a new environment facilitated the identification of hundreds of loci underlying ecological adaptation. A major question in the field of evolutionary biology is to what extent such an adaptive process involves selection of novel mutations with large effects or genetic changes at many loci, each with a small effect on phenotype (i.e., selection on standing genetic variation). Here we show that a missense mutation in rhodopsin (Phe261Tyr) is an adaptation to the red-shifted Baltic Sea light environment. The transition from phenylalanine to tyrosine differs only by the presence of a hydroxyl moiety in the latter, but this results in an up to 10-nm red-shifted light absorbance of the receptor. Remarkably, an examination of the rhodopsin sequences from 2,056 species of fish revealed that the same missense mutation has occurred independently and been selected for during at least 20 transitions between light environments across all fish. Our results provide a spectacular example of convergent evolution and how a single amino acid change can have a major effect on ecological adaptation.
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23
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Singh W, Bilal M, McClory J, Dourado D, Quinn D, Moody TS, Sutcliffe I, Huang M. Mechanism of Phosphatidylglycerol Activation Catalyzed by Prolipoprotein Diacylglyceryl Transferase. J Phys Chem B 2019; 123:7092-7102. [DOI: 10.1021/acs.jpcb.9b04227] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Warispreet Singh
- School of Chemistry & Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
- Department of Biocatalysis and Isotope Chemistry, Almac Sciences, Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, Northern Ireland, United Kingdom
| | - Munir Bilal
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, United Kingdom
| | - James McClory
- School of Chemistry & Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
| | - Daniel Dourado
- School of Chemistry & Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
- Department of Biocatalysis and Isotope Chemistry, Almac Sciences, Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, Northern Ireland, United Kingdom
| | - Derek Quinn
- Department of Biocatalysis and Isotope Chemistry, Almac Sciences, Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, Northern Ireland, United Kingdom
| | - Thomas S. Moody
- Department of Biocatalysis and Isotope Chemistry, Almac Sciences, Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, Northern Ireland, United Kingdom
- Arran Chemical Company Limited, Unit 1 Monksland Industrial Estate, Athlone, Co., Roscommon, N37 DN24, Ireland
| | - Iain Sutcliffe
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, United Kingdom
| | - Meilan Huang
- School of Chemistry & Chemical Engineering, Queen’s University Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
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24
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IJzerman AP, Guo D. Drug-Target Association Kinetics in Drug Discovery. Trends Biochem Sci 2019; 44:861-871. [PMID: 31101454 DOI: 10.1016/j.tibs.2019.04.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/28/2019] [Accepted: 04/08/2019] [Indexed: 02/07/2023]
Abstract
The important role of ligand-receptor binding kinetics in drug design and discovery is increasingly recognized by the drug research community. Over the past decade, accumulating evidence has shown that optimizing the ligand's dissociation rate constant can lead to desirable duration of in vivo target occupancy and, hence, improved pharmacodynamic properties. However, the association rate constant as a pharmacological principle remains less investigated, whereas it can play an equally important role in the selection of drug candidates. This review provides a compilation and discussion of otherwise scarce and dispersed information on this topic, bringing to light the importance of drug-target association in kinetics-directed drug design and discovery.
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Affiliation(s)
- Adriaan P IJzerman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research (LACDR), Leiden University, P.O. Box 9502, 2300, RA, Leiden, The Netherlands
| | - Dong Guo
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
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25
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Corradi V, Sejdiu BI, Mesa-Galloso H, Abdizadeh H, Noskov SY, Marrink SJ, Tieleman DP. Emerging Diversity in Lipid-Protein Interactions. Chem Rev 2019; 119:5775-5848. [PMID: 30758191 PMCID: PMC6509647 DOI: 10.1021/acs.chemrev.8b00451] [Citation(s) in RCA: 245] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Indexed: 02/07/2023]
Abstract
Membrane lipids interact with proteins in a variety of ways, ranging from providing a stable membrane environment for proteins to being embedded in to detailed roles in complicated and well-regulated protein functions. Experimental and computational advances are converging in a rapidly expanding research area of lipid-protein interactions. Experimentally, the database of high-resolution membrane protein structures is growing, as are capabilities to identify the complex lipid composition of different membranes, to probe the challenging time and length scales of lipid-protein interactions, and to link lipid-protein interactions to protein function in a variety of proteins. Computationally, more accurate membrane models and more powerful computers now enable a detailed look at lipid-protein interactions and increasing overlap with experimental observations for validation and joint interpretation of simulation and experiment. Here we review papers that use computational approaches to study detailed lipid-protein interactions, together with brief experimental and physiological contexts, aiming at comprehensive coverage of simulation papers in the last five years. Overall, a complex picture of lipid-protein interactions emerges, through a range of mechanisms including modulation of the physical properties of the lipid environment, detailed chemical interactions between lipids and proteins, and key functional roles of very specific lipids binding to well-defined binding sites on proteins. Computationally, despite important limitations, molecular dynamics simulations with current computer power and theoretical models are now in an excellent position to answer detailed questions about lipid-protein interactions.
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Affiliation(s)
- Valentina Corradi
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Besian I. Sejdiu
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Haydee Mesa-Galloso
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Haleh Abdizadeh
- Groningen
Biomolecular Sciences and Biotechnology Institute and Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Sergei Yu. Noskov
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute and Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - D. Peter Tieleman
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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26
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Szlenk CT, Gc JB, Natesan S. Does the Lipid Bilayer Orchestrate Access and Binding of Ligands to Transmembrane Orthosteric/Allosteric Sites of G Protein-Coupled Receptors? Mol Pharmacol 2019; 96:527-541. [PMID: 30967440 DOI: 10.1124/mol.118.115113] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 04/03/2019] [Indexed: 01/08/2023] Open
Abstract
The ligand-binding sites of many G protein-coupled receptors (GPCRs) are situated around and deeply embedded within the central pocket formed by their seven transmembrane-spanning α-helical domains. Generally, these binding sites are assumed accessible to endogenous ligands from the aqueous phase. Recent advances in the structural biology of GPCRs, along with biophysical and computational studies, suggest that amphiphilic and lipophilic molecules may gain access to these receptors by first partitioning into the membrane and then reaching the binding site via lateral diffusion through the lipid bilayer. In addition, several crystal structures of class A and class B GPCRs bound to their ligands offer unprecedented details on the existence of lipid-facing allosteric binding sites outside the transmembrane helices that can only be reached via lipid pathways. The highly organized structure of the lipid bilayer may direct lipophilic or amphiphilic drugs to a specific depth within the bilayer, changing local concentration of the drug near the binding site and affecting its binding kinetics. Additionally, the constraints of the lipid bilayer, including its composition and biophysical properties, may play a critical role in "pre-organizing" ligand molecules in an optimal orientation and conformation to facilitate receptor binding. Despite its clear involvement in molecular recognition processes, the critical role of the membrane in binding ligands to lipid-exposed transmembrane binding sites remains poorly understood and warrants comprehensive investigation. Understanding the mechanistic basis of the structure-membrane interaction relationship of drugs will not only provide useful insights about receptor binding kinetics but will also enhance our ability to take advantage of the apparent membrane contributions when designing drugs that target transmembrane proteins with improved efficacy and safety. In this minireview, we summarize recent structural and computational studies on membrane contributions to binding processes, elucidating both lipid pathways of ligand access and binding mechanisms for several orthosteric and allosteric ligands of class A and class B GPCRs.
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Affiliation(s)
- Christopher T Szlenk
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Jeevan B Gc
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Senthil Natesan
- College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
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27
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Sykes DA, Stoddart LA, Kilpatrick LE, Hill SJ. Binding kinetics of ligands acting at GPCRs. Mol Cell Endocrinol 2019; 485:9-19. [PMID: 30738950 PMCID: PMC6406023 DOI: 10.1016/j.mce.2019.01.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/19/2019] [Accepted: 01/19/2019] [Indexed: 12/31/2022]
Abstract
The influence of drug-receptor binding kinetics has often been overlooked during the development of new therapeutics that target G protein-coupled receptors (GPCRs). Over the last decade there has been a growing understanding that an in-depth knowledge of binding kinetics at GPCRs is required to successfully target this class of proteins. Ligand binding to a GPCR is often not a simple single step process with ligand freely diffusing in solution. This review will discuss the experiments and equations that are commonly used to measure binding kinetics and how factors such as allosteric regulation, rebinding and ligand interaction with the plasma membrane may influence these measurements. We will then consider the molecular characteristics of a ligand and if these can be linked to association and dissociation rates.
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Affiliation(s)
- David A Sykes
- Cell Signalling and Pharmacology Research Group, Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
| | - Leigh A Stoddart
- Cell Signalling and Pharmacology Research Group, Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
| | - Laura E Kilpatrick
- Cell Signalling and Pharmacology Research Group, Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
| | - Stephen J Hill
- Cell Signalling and Pharmacology Research Group, Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK.
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28
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Oakes V, Domene C. Influence of Cholesterol and Its Stereoisomers on Members of the Serotonin Receptor Family. J Mol Biol 2019; 431:1633-1649. [PMID: 30857969 DOI: 10.1016/j.jmb.2019.02.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 01/24/2023]
Abstract
Despite the ubiquity of cholesterol within the cell membrane, the mechanism by which it influences embedded proteins remains elusive. Numerous G-protein coupled receptors exhibit dramatic responses to membrane cholesterol with regard to the ligand-binding affinity and functional properties, including the 5-HT receptor family. Here, we use over 25 μs of unbiased atomistic molecular dynamics simulations to identify cholesterol interaction sites in the 5-HT1B and 5-HT2B receptors and evaluate their impact on receptor structure. Susceptibility to membrane cholesterol is shown to be subtype dependent and determined by the quality of interactions between the extracellular loops. Charged residues are essential for maintaining the arrangement of the extracellular surface in 5-HT2B; in the absence of such interactions, the extracellular surface of the 5-HT1B is malleable, populating a number of distinct conformations. Elevated cholesterol density near transmembrane helix 4 is considered to be conducive to the conformation of extracellular loop 2. Occupation of this site is also shown to be stereospecific, illustrated by differential behavior of nat-cholesterol isomers, ent- and epi-cholesterol. In simulations containing the endogenous agonist, serotonin, cholesterol binding at transmembrane helix 4 biases bound serotonin molecules toward an unexpected binding mode in the extended binding pocket. The results highlight the capability of membrane cholesterol to influence the mobility of the extracellular surface in the 5-HT1 receptor family and manipulate the architecture of the extracellular ligand-binding pocket.
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Affiliation(s)
- Victoria Oakes
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Carmen Domene
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK; Department of Chemistry, University of Oxford, Oxford, OX1 3TA, Oxford, UK.
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29
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Bokoch MP, Jo H, Valcourt JR, Srinivasan Y, Pan AC, Capponi S, Grabe M, Dror RO, Shaw DE, DeGrado WF, Coughlin SR. Entry from the Lipid Bilayer: A Possible Pathway for Inhibition of a Peptide G Protein-Coupled Receptor by a Lipophilic Small Molecule. Biochemistry 2018; 57:5748-5758. [PMID: 30102523 DOI: 10.1021/acs.biochem.8b00577] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pathways that G protein-coupled receptor (GPCR) ligands follow as they bind to or dissociate from their receptors are largely unknown. Protease-activated receptor-1 (PAR1) is a GPCR activated by intramolecular binding of a tethered agonist peptide that is exposed by thrombin cleavage. By contrast, the PAR1 antagonist vorapaxar is a lipophilic drug that binds in a pocket almost entirely occluded from the extracellular solvent. The binding and dissociation pathway of vorapaxar is unknown. Starting with the crystal structure of vorapaxar bound to PAR1, we performed temperature-accelerated molecular dynamics simulations of ligand dissociation. In the majority of simulations, vorapaxar exited the receptor laterally into the lipid bilayer through openings in the transmembrane helix (TM) bundle. Prior to full dissociation, vorapaxar paused in metastable intermediates stabilized by interactions with the receptor and lipid headgroups. Derivatives of vorapaxar with alkyl chains predicted to extend between TM6 and TM7 into the lipid bilayer inhibited PAR1 with apparent on rates similar to that of the parent compound in cell signaling assays. These data are consistent with vorapaxar binding to PAR1 via a pathway that passes between TM6 and TM7 from the lipid bilayer, in agreement with the most consistent pathway observed by molecular dynamics. While there is some evidence of entry of the ligand into rhodopsin and lipid-activated GPCRs from the cell membrane, our study provides the first such evidence for a peptide-activated GPCR and suggests that metastable intermediates along drug binding and dissociation pathways can be stabilized by specific interactions between lipids and the ligand.
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Affiliation(s)
- Michael P Bokoch
- Cardiovascular Research Institute , University of California , San Francisco , California 94158 , United States.,Department of Anesthesia and Perioperative Care , University of California , San Francisco , California 94143 , United States
| | - Hyunil Jo
- Department of Pharmaceutical Chemistry , University of California , San Francisco , California 94143 , United States
| | | | - Yoga Srinivasan
- Cardiovascular Research Institute , University of California , San Francisco , California 94158 , United States
| | - Albert C Pan
- D. E. Shaw Research , New York , New York 10036 , United States
| | - Sara Capponi
- Cardiovascular Research Institute , University of California , San Francisco , California 94158 , United States
| | - Michael Grabe
- Cardiovascular Research Institute , University of California , San Francisco , California 94158 , United States
| | - Ron O Dror
- D. E. Shaw Research , New York , New York 10036 , United States
| | - David E Shaw
- D. E. Shaw Research , New York , New York 10036 , United States.,Department of Biochemistry and Molecular Biophysics , Columbia University , New York , New York 10032 , United States
| | - William F DeGrado
- Department of Pharmaceutical Chemistry , University of California , San Francisco , California 94143 , United States
| | - Shaun R Coughlin
- Cardiovascular Research Institute , University of California , San Francisco , California 94158 , United States
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30
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Full rescue of an inactive olfactory receptor mutant by elimination of an allosteric ligand-gating site. Sci Rep 2018; 8:9631. [PMID: 29941999 PMCID: PMC6018111 DOI: 10.1038/s41598-018-27790-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/31/2018] [Indexed: 11/25/2022] Open
Abstract
Ligand-gating has recently been proposed as a novel mechanism to regulate olfactory receptor sensitivity. TAAR13c, the zebrafish olfactory receptor activated by the death-associated odor cadaverine, appears to possess an allosteric binding site for cadaverine, which was assumed to block progress of the ligand towards the internal orthosteric binding-and-activation site. Here we have challenged the suggested gating mechanism by modeling the entry tunnel for the ligand as well as the ligand path inside the receptor. We report an entry tunnel, whose opening is blocked by occupation of the external binding site by cadaverine, confirming the hypothesized gating mechanism. A multistep docking algorithm suggested a plausible path for cadaverine from the allosteric to the orthosteric binding-and-activation site. Furthermore we have combined a gain-of-function gating site mutation and a loss-of-function internal binding site mutation in one recombinant receptor. This receptor had almost wildtype ligand affinities, consistent with modeling results that showed localized effects for each mutation. A novel mutation of the suggested gating site resulted in increased receptor ligand affinity. In summary both the experimental and the modeling results provide further evidence for the proposed gating mechanism, which surprisingly exhibits pronounced similarity to processes described for some metabotropic neurotransmitter receptors.
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31
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Di Scala C, Fantini J, Yahi N, Barrantes FJ, Chahinian H. Anandamide Revisited: How Cholesterol and Ceramides Control Receptor-Dependent and Receptor-Independent Signal Transmission Pathways of a Lipid Neurotransmitter. Biomolecules 2018; 8:biom8020031. [PMID: 29789479 PMCID: PMC6022874 DOI: 10.3390/biom8020031] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/02/2018] [Accepted: 05/16/2018] [Indexed: 12/13/2022] Open
Abstract
Anandamide is a lipid neurotransmitter derived from arachidonic acid, a polyunsaturated fatty acid. The chemical differences between anandamide and arachidonic acid result in a slightly enhanced solubility in water and absence of an ionisable group for the neurotransmitter compared with the fatty acid. In this review, we first analyze the conformational flexibility of anandamide in aqueous and membrane phases. We next study the interaction of the neurotransmitter with membrane lipids and discuss the molecular basis of the unexpected selectivity of anandamide for cholesterol and ceramide from among other membrane lipids. We show that cholesterol behaves as a binding partner for anandamide, and that following an initial interaction mediated by the establishment of a hydrogen bond, anandamide is attracted towards the membrane interior, where it forms a molecular complex with cholesterol after a functional conformation adaptation to the apolar membrane milieu. The complex is then directed to the anandamide cannabinoid receptor (CB1) which displays a high affinity binding pocket for anandamide. We propose that cholesterol may regulate the entry and exit of anandamide in and out of CB1 by interacting with low affinity cholesterol recognition sites (CARC and CRAC) located in transmembrane helices. The mirror topology of cholesterol binding sites in the seventh transmembrane domain is consistent with the delivery, extraction and flip-flop of anandamide through a coordinated cholesterol-dependent mechanism. The binding of anandamide to ceramide illustrates another key function of membrane lipids which may occur independently of protein receptors. Interestingly, ceramide forms a tight complex with anandamide which blocks the degradation pathway of both lipids and could be exploited for anti-cancer therapies.
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Affiliation(s)
- Coralie Di Scala
- INMED, INSERM U1249, Parc Scientifique de Luminy, 163 Avenue de Luminy, BP13 13273 Marseille CEDEX 09, France.
| | - Jacques Fantini
- INSERM UMR_S 1072, Aix-Marseille Université, 13015 Marseille, France.
| | - Nouara Yahi
- INSERM UMR_S 1072, Aix-Marseille Université, 13015 Marseille, France.
| | - Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Biomedical Research Institute (BIOMED), UCA⁻CONICET, Av. Alicia Moreau de Justo 1600, C1107AFF Buenos Aires, Argentina.
| | - Henri Chahinian
- INSERM UMR_S 1072, Aix-Marseille Université, 13015 Marseille, France.
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32
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Yuan X, Raniolo S, Limongelli V, Xu Y. The Molecular Mechanism Underlying Ligand Binding to the Membrane-Embedded Site of a G-Protein-Coupled Receptor. J Chem Theory Comput 2018; 14:2761-2770. [PMID: 29660291 DOI: 10.1021/acs.jctc.8b00046] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crystal structure of P2Y1 receptor (P2Y1R), a class A GPCR, revealed a special extra-helical site for its antagonist, BPTU, which locates in-between the membrane and the protein. However, due to the limitation of crystallization experiments, the membrane was mimicked by use of detergents, and the information related to the binding of BPTU to the receptor in the membrane environment is rather limited. In the present work, we conducted a total of ∼7.5 μs all-atom simulations in explicit solvent using conventional molecular dynamics and multiple enhanced sampling methods, with models of BPTU and a POPC bilayer, both in the absence and presence of P2Y1R. Our simulations revealed that BPTU prefers partitioning into the interface of polar/lipophilic region of the lipid bilayer before associating with the receptor. Then, it interacts with the second extracellular loop of the receptor and reaches the binding site through the lipid-receptor interface. In addition, by use of funnel-metadynamics simulations which efficiently enhance the sampling of bound and unbound states, we provide a statistically accurate description of the underlying binding free energy landscape. The calculated absolute ligand-receptor binding affinity is in excellent agreement with the experimental data (Δ Gb0_theo = -11.5 kcal mol-1, Δ Gb0_exp= -11.7 kcal mol-1). Our study broadens the view of the current experimental/theoretical models and our understanding of the protein-ligand recognition mechanism in the lipid environment. The strategy used in this work is potentially applicable to investigate ligands association/dissociation with other membrane-embedded sites, allowing identification of compounds targeting membrane receptors of pharmacological interest.
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Affiliation(s)
- Xiaojing Yuan
- CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica , Chinese Academy of Sciences (CAS) , Shanghai 201203 , China.,School of Pharmacy , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Stefano Raniolo
- Faculty of Biomedical Sciences, Institute of Computational Science - Center for Computational Medicine in Cardiology , Università della Svizzera Italiana (USI) , CH-6900 Lugano , Switzerland
| | - Vittorio Limongelli
- Faculty of Biomedical Sciences, Institute of Computational Science - Center for Computational Medicine in Cardiology , Università della Svizzera Italiana (USI) , CH-6900 Lugano , Switzerland.,Department of Pharmacy , University of Naples "Federico II" , I-80131 Naples , Italy
| | - Yechun Xu
- CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica , Chinese Academy of Sciences (CAS) , Shanghai 201203 , China.,School of Pharmacy , University of Chinese Academy of Sciences , Beijing 100049 , China
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33
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Kayikci M, Venkatakrishnan AJ, Scott-Brown J, Ravarani CNJ, Flock T, Babu MM. Visualization and analysis of non-covalent contacts using the Protein Contacts Atlas. Nat Struct Mol Biol 2018; 25:185-194. [PMID: 29335563 PMCID: PMC5837000 DOI: 10.1038/s41594-017-0019-z] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 12/11/2017] [Indexed: 11/09/2022]
Abstract
Visualizations of biomolecular structures empower us to gain insights into biological functions, generate testable hypotheses, and communicate biological concepts. Typical visualizations (such as ball and stick) primarily depict covalent bonds. In contrast, non-covalent contacts between atoms, which govern normal physiology, pathogenesis, and drug action, are seldom visualized. We present the Protein Contacts Atlas, an interactive resource of non-covalent contacts from over 100,000 PDB crystal structures. We developed multiple representations for visualization and analysis of non-covalent contacts at different scales of organization: atoms, residues, secondary structure, subunits, and entire complexes. The Protein Contacts Atlas enables researchers from different disciplines to investigate diverse questions in the framework of non-covalent contacts, including the interpretation of allostery, disease mutations and polymorphisms, by exploring individual subunits, interfaces, and protein-ligand contacts and by mapping external information. The Protein Contacts Atlas is available at http://www.mrc-lmb.cam.ac.uk/pca/ and also through PDBe.
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Affiliation(s)
- Melis Kayikci
- MRC Laboratory of Molecular Biology, Cambridge, UK.
- Genomics England, London, UK.
| | - A J Venkatakrishnan
- MRC Laboratory of Molecular Biology, Cambridge, UK.
- Department of Molecular and Cellular Physiology, Department of Computer Science, and Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA.
| | - James Scott-Brown
- MRC Laboratory of Molecular Biology, Cambridge, UK
- University of Oxford, Oxford, UK
| | | | - Tilman Flock
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Fitzwilliam College, University of Cambridge, Cambridge, UK
- Paul Scherrer Institute, Villigen, Switzerland
| | - M Madan Babu
- MRC Laboratory of Molecular Biology, Cambridge, UK.
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34
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Tian H, Sakmar TP, Huber T. The Energetics of Chromophore Binding in the Visual Photoreceptor Rhodopsin. Biophys J 2017; 113:60-72. [PMID: 28700926 DOI: 10.1016/j.bpj.2017.05.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 05/04/2017] [Accepted: 05/25/2017] [Indexed: 01/06/2023] Open
Abstract
The visual photoreceptor rhodopsin is a prototypical G-protein-coupled receptor (GPCR) that stabilizes its inverse agonist ligand, 11-cis-retinal (11CR), by a covalent, protonated Schiff base linkage. In the visual dark adaptation, the fundamental molecular event after photobleaching of rhodopsin is the recombination reaction between its apoprotein opsin and 11CR. Here we present a detailed analysis of the kinetics and thermodynamics of this reaction, also known as the "regeneration reaction". We compared the regeneration of purified rhodopsin reconstituted into phospholipid/detergent bicelles with rhodopsin reconstituted into detergent micelles. We found that the lipid bilayer of bicelles stabilized the chromophore-free opsin over the long timescale required for the regeneration experiments, and also facilitated the ligand reuptake binding reaction. We utilized genetic code expansion and site-specific bioorthogonal labeling of rhodopsin with Alexa488 to enable, to our knowledge, a novel fluorescence resonance energy transfer-based measurement of the binding kinetics between opsin and 11CR. Based on these results, we report a complete energy diagram for the regeneration reaction of rhodopsin. We show that the dissociation reaction of rhodopsin to 11CR and opsin has a 25-pM equilibrium dissociation constant, which corresponds to only 0.3 kcal/mol stabilization compared to the noncovalent, tightly bound antagonist-GPCR complex of iodopindolol and β-adrenergic receptor. However, 11CR dissociates four orders-of-magnitude slower than iodopindolol, which corresponds to a 6-kcal/mol higher dissociation free energy barrier. We further used isothermal titration calorimetry to show that ligand binding in rhodopsin is enthalpy driven with -22 kcal/mol, which is 12 kcal/mol more stable than the antagonist-GPCR complex. Our data provide insights into the ligand-receptor binding reaction for rhodopsin in particular, and for GPCRs more broadly.
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Affiliation(s)
- He Tian
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York
| | - Thomas P Sakmar
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York; Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Center for Alzheimer Research, Karolinska Institutet, Huddinge, Sweden.
| | - Thomas Huber
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York.
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35
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Yan S, Shaw DE, Yang L, Sandham DA, Healy MP, Reilly J, Wang B. Interactions between β2-Adrenoceptor Ligands and Membrane: Atomic-Level Insights from Magic-Angle Spinning NMR. J Med Chem 2017; 60:6867-6879. [PMID: 28703592 DOI: 10.1021/acs.jmedchem.7b00205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To understand the relationship between structural properties of the β2-adrenoceptor ligands and their interactions with membranes, we have investigated the location and distribution of five β2 agonists with distinct clinical durations and onsets of action (indacaterol, two indacaterol analogues, salmeterol and formoterol) in monounsaturated model membranes using magic angle spinning NMR to measure these interactions through both 1H nuclear Overhauser enhancement (NOE) and paramagnetic relaxation enhancement (PRE) techniques. The hydrophilic aromatic groups of all five β2 agonists show maximum distribution in the lipid/water interface, but distinct location and dynamic behavior were observed for the lipophilic aromatic rings. Our study elucidates at atomic level that the hydrophobicity and substitution geometry of lipophilic groups play important roles in compound-lipid interactions.
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Affiliation(s)
- Si Yan
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research , Cambridge, Massachusetts 02139, United States
| | - Duncan E Shaw
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research , Cambridge, Massachusetts 02139, United States
| | - Linhong Yang
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research , Cambridge, Massachusetts 02139, United States
| | - David A Sandham
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research , Cambridge, Massachusetts 02139, United States
| | - Mark P Healy
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research , Cambridge, Massachusetts 02139, United States
| | - John Reilly
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research , Cambridge, Massachusetts 02139, United States
| | - Bing Wang
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research , Cambridge, Massachusetts 02139, United States
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36
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Lynch DL, Hurst DP, Shore DM, Pitman MC, Reggio PH. Molecular Dynamics Methodologies for Probing Cannabinoid Ligand/Receptor Interaction. Methods Enzymol 2017; 593:449-490. [PMID: 28750815 PMCID: PMC5802876 DOI: 10.1016/bs.mie.2017.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cannabinoid type 1 and 2 G-protein-coupled receptors are currently important pharmacological targets with significant drug discovery potential. These receptors have been shown to display functional selectivity or biased agonism, a property currently thought to have substantial therapeutic potential. Although recent advances in crystallization techniques have provided a wealth of structural information about this important class of membrane-embedded proteins, these structures lack dynamical information. In order to fully understand the interplay of structure and function for this important class of proteins, complementary techniques that address the dynamical aspects of their function are required such as NMR as well as a variety of other spectroscopies. Complimentary to these experimental approaches is molecular dynamics, which has been effectively used to help unravel, at the atomic level, the dynamics of ligand binding and activation of these membrane-bound receptors. Here, we discuss and present several representative examples of the application of molecular dynamics simulations to the understanding of the signatures of ligand-binding and -biased signaling at the cannabinoid type 1 and 2 receptors.
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Affiliation(s)
- Diane L Lynch
- University of North Carolina at Greensboro, Greensboro, NC, United States.
| | - Dow P Hurst
- University of North Carolina at Greensboro, Greensboro, NC, United States
| | - Derek M Shore
- University of North Carolina at Greensboro, Greensboro, NC, United States
| | - Mike C Pitman
- University of North Carolina at Greensboro, Greensboro, NC, United States
| | - Patricia H Reggio
- University of North Carolina at Greensboro, Greensboro, NC, United States
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37
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Morrow JM, Castiglione GM, Dungan SZ, Tang PL, Bhattacharyya N, Hauser FE, Chang BSW. An experimental comparison of human and bovine rhodopsin provides insight into the molecular basis of retinal disease. FEBS Lett 2017; 591:1720-1731. [PMID: 28369862 DOI: 10.1002/1873-3468.12637] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/22/2017] [Accepted: 03/25/2017] [Indexed: 11/05/2022]
Abstract
Rhodopsin is the visual pigment that mediates dim-light vision in vertebrates and is a model system for the study of retinal disease. The majority of rhodopsin experiments are performed using bovine rhodopsin; however, recent evidence suggests that significant functional differences exist among mammalian rhodopsins. In this study, we identify differences in both thermal decay and light-activated retinal release rates between bovine and human rhodopsin and perform mutagenesis studies to highlight two clusters of substitutions that contribute to these differences. We also demonstrate that the retinitis pigmentosa-associated mutation G51A behaves differently in human rhodopsin compared to bovine rhodopsin and determine that the thermal decay rate of an ancestrally reconstructed mammalian rhodopsin displays an intermediate phenotype compared to the two extant pigments.
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Affiliation(s)
- James M Morrow
- Department of Cell and Systems Biology, University of Toronto, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | | | - Sarah Z Dungan
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | - Portia L Tang
- Department of Cell and Systems Biology, University of Toronto, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | | | - Frances E Hauser
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | - Belinda S W Chang
- Department of Cell and Systems Biology, University of Toronto, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Canada
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38
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Tomobe K, Yamamoto E, Kholmurodov K, Yasuoka K. Water permeation through the internal water pathway in activated GPCR rhodopsin. PLoS One 2017; 12:e0176876. [PMID: 28493967 PMCID: PMC5426653 DOI: 10.1371/journal.pone.0176876] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 04/18/2017] [Indexed: 12/13/2022] Open
Abstract
Rhodopsin is a light-driven G-protein-coupled receptor that mediates signal transduction in eyes. Internal water molecules mediate activation of the receptor in a rhodopsin cascade reaction and contribute to conformational stability of the receptor. However, it remains unclear how internal water molecules exchange between the bulk and protein inside, in particular through a putative solvent pore on the cytoplasmic. Using all-atom molecular dynamics simulations, we identified the solvent pore on cytoplasmic side in both the Meta II state and the Opsin. On the other hand, the solvent pore does not exist in the dark-adapted rhodopsin. We revealed two characteristic narrow regions located within the solvent pore in the Meta II state. The narrow regions distinguish bulk and the internal hydration sites, one of which is adjacent to the conserved structural motif "NPxxY". Water molecules in the solvent pore diffuse by pushing or sometimes jumping a preceding water molecule due to the geometry of the solvent pore. These findings revealed a total water flux between the bulk and the protein inside in the Meta II state, and suggested that these pathways provide water molecules to the crucial sites of the activated rhodopsin.
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Affiliation(s)
- Katsufumi Tomobe
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Eiji Yamamoto
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Kholmirzo Kholmurodov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, 141980, Russia
- Dubna State University, Dubna, 141980, Russia
| | - Kenji Yasuoka
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
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39
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Kaylor JJ, Xu T, Ingram NT, Tsan A, Hakobyan H, Fain GL, Travis GH. Blue light regenerates functional visual pigments in mammals through a retinyl-phospholipid intermediate. Nat Commun 2017; 8:16. [PMID: 28473692 PMCID: PMC5432035 DOI: 10.1038/s41467-017-00018-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 02/15/2017] [Indexed: 11/24/2022] Open
Abstract
The light absorbing chromophore in opsin visual pigments is the protonated Schiff base of 11-cis-retinaldehyde (11cRAL). Absorption of a photon isomerizes 11cRAL to all-trans-retinaldehyde (atRAL), briefly activating the pigment before it dissociates. Light sensitivity is restored when apo-opsin combines with another 11cRAL to form a new visual pigment. Conversion of atRAL to 11cRAL is carried out by enzyme pathways in neighboring cells. Here we show that blue (450-nm) light converts atRAL specifically to 11cRAL through a retinyl-phospholipid intermediate in photoreceptor membranes. The quantum efficiency of this photoconversion is similar to rhodopsin. Photoreceptor membranes synthesize 11cRAL chromophore faster under blue light than in darkness. Live mice regenerate rhodopsin more rapidly in blue light. Finally, whole retinas and isolated cone cells show increased photosensitivity following exposure to blue light. These results indicate that light contributes to visual-pigment renewal in mammalian rods and cones through a non-enzymatic process involving retinyl-phospholipids. It is currently thought that visual pigments in vertebrate photoreceptors are regenerated exclusively through enzymatic cycles. Here the authors show that mammalian photoreceptors also regenerate opsin pigments in light through photoisomerization of N-ret-PE (N-retinylidene-phosphatidylethanolamine.
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Affiliation(s)
- Joanna J Kaylor
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Tongzhou Xu
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA.,Molecular, Cellular and Integrative Physiology Graduate Program, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Norianne T Ingram
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA.,Molecular, Cellular and Integrative Physiology Graduate Program, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Avian Tsan
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Hayk Hakobyan
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Gordon L Fain
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA.,Department of Integrative Biology and Physiology, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA
| | - Gabriel H Travis
- Jules Stein Eye Institute, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA. .,Department of Biological Chemistry, University of California Los Angeles School of Medicine, Los Angeles, California, 90095, USA.
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40
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Caliman AD, Miao Y, McCammon JA. Activation mechanisms of the first sphingosine-1-phosphate receptor. Protein Sci 2017; 26:1150-1160. [PMID: 28370663 DOI: 10.1002/pro.3165] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 02/24/2017] [Accepted: 03/19/2017] [Indexed: 12/12/2022]
Abstract
Activation of the first sphingosine-1-phosphate receptor (S1PR1 ) promotes permeability of the blood brain barrier, astrocyte and neuronal protection, and lymphocyte egress from secondary lymphoid tissues. Although an agonist often activates the S1PR1 , the receptor exhibits high levels of basal activity. In this study, we performed long-timescale molecular dynamics and accelerated molecular dynamics (aMD) simulations to investigate activation mechanisms of the ligand-free (apo) S1PR1 . In the aMD enhanced sampling simulations, we observed four independent events of activation, which is characterized by close interaction between Y3117.53 and Y2215.58 and increased distance between the intracellular ends of transmembrane (TM) helices 3 and 6. Although TM helices TM3, TM6, TM5 and, TM7 are associated with GPCR activation, we discovered that their movements are not necessarily correlated during activation. Instead, TM5 showed a decreased correlation with each of these regions during activation. During activation of the apo receptor, Y2215.58 and Y3117.53 became more solvated, because a water channel formed in the intracellular pocket. Additionally, a lipid molecule repeatedly entered the receptor between the extracellular ends of TM1 and TM7, providing important insights into the pathway of ligand entry into the S1PR1 .
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Affiliation(s)
- Alisha D Caliman
- Department of Pharmacology, University of California at San Diego, La Jolla, California, 92093
| | - Yinglong Miao
- Department of Pharmacology, University of California at San Diego, La Jolla, California, 92093.,Howard Hughes Medical Institute, University of California at San Diego, La Jolla, California, 92093
| | - J Andrew McCammon
- Department of Pharmacology, University of California at San Diego, La Jolla, California, 92093.,Howard Hughes Medical Institute, University of California at San Diego, La Jolla, California, 92093.,Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California, 92093
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41
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Membrane cholesterol access into a G-protein-coupled receptor. Nat Commun 2017; 8:14505. [PMID: 28220900 PMCID: PMC5321766 DOI: 10.1038/ncomms14505] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 01/05/2017] [Indexed: 12/25/2022] Open
Abstract
Cholesterol is a key component of cell membranes with a proven modulatory role on the function and ligand-binding properties of G-protein-coupled receptors (GPCRs). Crystal structures of prototypical GPCRs such as the adenosine A2A receptor (A2AR) have confirmed that cholesterol finds stable binding sites at the receptor surface suggesting an allosteric role of this lipid. Here we combine experimental and computational approaches to show that cholesterol can spontaneously enter the A2AR-binding pocket from the membrane milieu using the same portal gate previously suggested for opsin ligands. We confirm the presence of cholesterol inside the receptor by chemical modification of the A2AR interior in a biotinylation assay. Overall, we show that cholesterol's impact on A2AR-binding affinity goes beyond pure allosteric modulation and unveils a new interaction mode between cholesterol and the A2AR that could potentially apply to other GPCRs. G-protein-coupled receptors trigger several signalling pathways and their activity was proposed to be allosteric modulated by cholesterol. Here the authors use molecular dynamics simulations and ligand binding assays to show that membrane cholesterol can bind to adenosine A2A receptor orthosteric site.
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42
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Dong X, Herrera-Hernández MG, Ramon E, Garriga P. Docosahexaenoic acid phospholipid differentially modulates the conformation of G90V and N55K rhodopsin mutants associated with retinitis pigmentosa. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:975-981. [PMID: 28212859 DOI: 10.1016/j.bbamem.2017.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 02/09/2017] [Accepted: 02/11/2017] [Indexed: 11/26/2022]
Abstract
Rhodopsin is the visual photoreceptor of the retinal rod cells that mediates dim light vision and a prototypical member of the G protein-coupled receptor superfamily. The structural stability and functional performance of rhodopsin are modulated by membrane lipids. Docosahexaenoic acid has been shown to interact with native rhodopsin but no direct evidence has been established on the effect of such lipid on the stability and regeneration of rhodopsin mutants associated with retinal diseases. The stability and regeneration of two thermosensitive mutants G90V and N55K, associated with the retinal degenerative disease retinitis pigmentosa, have been analyzed in docosohexaenoic phospholipid (1,2-didocosa-hexaenoyl-sn-glycero-3-phosphocholine; DDHA-PC) liposomes. G90V mutant reconstituted in DDHA-PC liposomes significantly increased its thermal stability, but N55K mutant showed similar thermal sensitivity both in dodecyl maltoside detergent solution and in DDHA-PC liposomes. The retinal release process, measured by fluorescence spectroscopy, became faster in the lipid system for the two mutants. The opsin conformation was stabilized for the G90V mutant allowing improved retinal uptake whereas no chromophore binding could be detected for N55K opsin after photoactivation. The results emphasize the distinct role of DHA on different phenotypic rhodopsin mutations associated with classical (G90V) and sector (N55K) retinitis pigmentosa.
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Affiliation(s)
- Xiaoyun Dong
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - María Guadalupe Herrera-Hernández
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - Eva Ramon
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain
| | - Pere Garriga
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, Rambla de Sant Nebridi 22, 08222 Terrassa, Catalonia, Spain.
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43
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Jakowiecki J, Filipek S. Hydrophobic Ligand Entry and Exit Pathways of the CB1 Cannabinoid Receptor. J Chem Inf Model 2016; 56:2457-2466. [DOI: 10.1021/acs.jcim.6b00499] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Jakub Jakowiecki
- Faculty of Chemistry, Biological
and Chemical Research Centre, University of Warsaw, ul. Pasteura
1, 02-093 Warsaw, Poland
| | - Slawomir Filipek
- Faculty of Chemistry, Biological
and Chemical Research Centre, University of Warsaw, ul. Pasteura
1, 02-093 Warsaw, Poland
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44
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Emtage AL, Mistry SN, Fischer PM, Kellam B, Laughton CA. GPCRs through the keyhole: the role of protein flexibility in ligand binding to β-adrenoceptors. J Biomol Struct Dyn 2016; 35:2604-2619. [DOI: 10.1080/07391102.2016.1226197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Abigail L. Emtage
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Shailesh N. Mistry
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Peter M. Fischer
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Barrie Kellam
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Charles A. Laughton
- School of Pharmacy and Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
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45
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Vauquelin G. Cell membranes… and how long drugs may exert beneficial pharmacological activity in vivo. Br J Clin Pharmacol 2016; 82:673-82. [PMID: 27135195 PMCID: PMC5338106 DOI: 10.1111/bcp.12996] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 04/28/2016] [Accepted: 04/28/2016] [Indexed: 12/14/2022] Open
Abstract
The time course of the beneficial pharmacological effect of a drug has long been considered to depend merely on the temporal fluctuation of its free concentration. Only in the last decade has it become widely accepted that target-binding kinetics can also affect in vivo pharmacological activity. Although current reviews still essentially focus on genuine dissociation rates, evidence is accumulating that additional micro-pharmacokinetic (PK) and -pharmacodynamic (PD) mechanisms, in which the cell membrane plays a central role, may also increase the residence time of a drug on its target. The present review provides a compilation of otherwise widely dispersed information on this topic. The cell membrane can intervene in drug binding via the following three major mechanisms: (i) by acting as a sink/repository for the drug; (ii) by modulating the conformation of the drug and even by participating in the binding process; and (iii) by facilitating the approach (and rebinding) of the drug to the target. To highlight these mechanisms, we focus on drugs that are currently used in clinical therapy, such as the antihypertensive angiotensin II type 1 receptor antagonist candesartan, the atypical antipsychotic agent clozapine and the bronchodilator salmeterol. Although the role of cell membranes in PK-PD modelling is gaining increasing interest, many issues remain unresolved. It is likely that novel biophysical and computational approaches will provide improved insights in the near future.
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Affiliation(s)
- Georges Vauquelin
- Department Molecular and Biochemical PharmacologyVrije Universiteit BrusselBrusselsBelgium
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46
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Interaction of G protein coupled receptors and cholesterol. Chem Phys Lipids 2016; 199:61-73. [PMID: 27108066 DOI: 10.1016/j.chemphyslip.2016.04.006] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/30/2016] [Accepted: 04/19/2016] [Indexed: 12/20/2022]
Abstract
G protein coupled receptors (GPCRs) form the largest receptor superfamily in eukaryotic cells. Owing to their seven transmembrane helices, large parts of these proteins are embedded in the cholesterol-rich plasma membrane bilayer. Thus, GPCRs are always in proximity to cholesterol. Some of them are functionally dependent on the specific presence of cholesterol. Over the last years, enormous progress on receptor structures has been achieved. While lipophilic ligands other than cholesterol have been shown to bind either inside the helix bundle or at the receptor-lipid interface, the binding site of cholesterol was either a single transmembrane helix or a groove between two or more transmembrane helices. A clear preference for one of the two membrane leaflets has not been observed. Not surprisingly, many hydrophobic residues (primarily leucine and isoleucine) were found to be involved in cholesterol binding. In most cases, the rough β-face of cholesterol contacted the transmembrane helix bundle rather than the surrounding lipid matrix. The polar hydroxy group of cholesterol was localized near the water-membrane interface with potential hydrogen bonding to residues in receptor loop regions. Although a canonical motif, designated as CCM site, was detected as a specific cholesterol binding site in case of the β2AR, this site was not found to be occupied by cholesterol in other GPCRs possessing the same motif. Cholesterol-receptor interactions can increase the compactness of the receptor structure and are able to enhance the conformational stability towards active or inactive receptor states. Overall, all current data suggest a high plasticity of cholesterol interaction sites in GPCRs.
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47
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The pathway of ligand entry from the membrane bilayer to a lipid G protein-coupled receptor. Sci Rep 2016; 6:22639. [PMID: 26940769 PMCID: PMC4778059 DOI: 10.1038/srep22639] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 02/18/2016] [Indexed: 01/04/2023] Open
Abstract
The binding process through the membrane bilayer of lipid-like ligands to a protein target is an important but poorly explored recognition process at the atomic level. In this work we succeeded in resolving the binding of the lipid inhibitor ML056 to the sphingosine-1-phosphate receptor 1 (S1P1R) using unbiased molecular dynamics simulations with an aggregate sampling of over 800 μs. The binding pathway is a multi-stage process consisting of the ligand diffusing in the bilayer leaflet to contact a "membrane vestibule" at the top of TM 7, subsequently moving from this lipid-facing vestibule to the orthosteric binding cavity through a channel formed by TMs 1 and 7 and the N-terminal of the receptor. Unfolding of the N-terminal alpha-helix increases the volume of the channel upon ligand entry, helping to reach the crystallographic pose that also corresponds to the predicted favorable pose. The relaxation timescales of the binding process show that the binding of the ligand to the "membrane vestibule" is the rate-limiting step in the multi microseconds timescale. We comment on the significance and parallels of the binding process in the context of other binding studies.
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48
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Srinivasan S, Cordomí A, Ramon E, Garriga P. Beyond spectral tuning: human cone visual pigments adopt different transient conformations for chromophore regeneration. Cell Mol Life Sci 2016; 73:1253-63. [PMID: 26387074 PMCID: PMC11108329 DOI: 10.1007/s00018-015-2043-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 09/09/2015] [Accepted: 09/10/2015] [Indexed: 01/01/2023]
Abstract
Human red and green visual pigments are seven transmembrane receptors of cone photoreceptor cells of the retina that mediate color vision. These pigments share a very high degree of homology and have been assumed to feature analogous structural and functional properties. We report on a different regeneration mechanism among red and green cone opsins with retinal analogs using UV-Vis/fluorescence spectroscopic analyses, molecular modeling and site-directed mutagenesis. We find that photoactivated green cone opsin adopts a transient conformation which regenerates via an unprotonated Schiff base linkage with its natural chromophore, whereas red cone opsin forms a typical protonated Schiff base. The chromophore regeneration kinetics is consistent with a secondary retinal uptake by the cone pigments. Overall, our findings reveal, for the first time, structural differences in the photoactivated conformation between red and green cone pigments that may be linked to their molecular evolution, and support the proposal of secondary retinal binding to visual pigments, in addition to binding to the canonical primary site, which may serve as a regulatory mechanism of dark adaptation in the phototransduction process.
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Affiliation(s)
- Sundaramoorthy Srinivasan
- Departament d'Enginyeria Química, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, Rambla de Sant Nebridi 22, 08222, Terrassa, Spain
| | - Arnau Cordomí
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193, Barcelona, Spain
| | - Eva Ramon
- Departament d'Enginyeria Química, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, Rambla de Sant Nebridi 22, 08222, Terrassa, Spain
| | - Pere Garriga
- Departament d'Enginyeria Química, Centre de Biotecnologia Molecular, Universitat Politècnica de Catalunya, Rambla de Sant Nebridi 22, 08222, Terrassa, Spain.
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Torres-Dowdall J, Henning F, Elmer KR, Meyer A. Ecological and Lineage-Specific Factors Drive the Molecular Evolution of Rhodopsin in Cichlid Fishes. Mol Biol Evol 2015; 32:2876-82. [DOI: 10.1093/molbev/msv159] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Vauquelin G. On the 'micro'-pharmacodynamic and pharmacokinetic mechanisms that contribute to long-lasting drug action. Expert Opin Drug Discov 2015; 10:1085-98. [PMID: 26165720 DOI: 10.1517/17460441.2015.1067196] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Optimal drug therapy often requires continuing high levels of target occupancy. Besides the traditional pharmacokinetic (PK) contribution thereto, drug-target interactions that comprise successive 'microscopic' steps as well as the intervention of the cell membrane and other 'micro'-anatomical structures nearby may help attaining this objective. AREAS COVERED This article reviews the 'micro'-pharmacodynamic (PD) and PK mechanisms that may increase a drug's residence time. Special focus is on induced-fit- and bivalent ligand binding models as well as on the ability of the plasma membrane surrounding the target to act as a repository for the drug (e.g., microkinetic model), to actively participate in the binding process (e.g., exosite model) and, along with microanatomical elements like synapses and interstitial spaces, to act on the drug's diffusion properties (reduction in dimensionality and drug-rebinding models). EXPERT OPINION The PK profile, as well as the target dissociation kinetics of a drug, may fail to account for its long-lasting efficiency in intact tissues and in vivo. This lacuna could potentially be alleviated by incorporating some of the enumerated 'microscopic' mechanisms and, to unveil them, dedicated experiments on sufficiently physiologically relevant biological material like cell monolayers can already be implemented early on in the lead optimization process.
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Affiliation(s)
- Georges Vauquelin
- a Free University Brussels (VUB), Molecular and Biochemical Pharmacology Department , Pleinlaan 2, B-1050 Brussels, Belgium +32 2 6291955 ; +32 2 6291358 ;
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