1
|
González-Del Pino GL, Walsh RM, Atanasiu D, Cairns TM, Saw WT, Cohen GH, Heldwein EE. Allosteric mechanism of membrane fusion activation in a herpesvirus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.20.610514. [PMID: 39345478 PMCID: PMC11430019 DOI: 10.1101/2024.09.20.610514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/01/2024]
Abstract
Herpesviridae infect nearly all humans for life, causing diseases that range from painful to life-threatening 1 . These viruses penetrate cells by employing a complex apparatus composed of separate receptor-binding, signal-transmitting, and membrane-fusing components 2 . But how these components coordinate their functions is unknown. Here, we determined the 4.19-angstrom cryoEM reconstruction of the central signal-transmitting component from herpes simplex virus 2, the gH/gL complex, in its elusive pre-activation state. Analysis of the continuum of conformational ensembles observed in cryoEM data revealed a series of structural rearrangements in gH/gL that allosterically transmit the fusion-triggering signal from the receptor-binding glycoprotein gD to the membrane fusogen gB. Furthermore, we identified a structural "switch" element in gH/gL that refolds and flips 180 degrees during the transition from pre-activation to activated form. Conservation of this "switch" in gH/gL homologs suggests that the proposed fusion triggering mechanism may apply to all Herpesviridae and points to a new target for subunit-based vaccines and treatment efforts.
Collapse
|
2
|
Liu F, Li T, Gong H, Tian F, Bai Y, Wang H, Yang C, Li Y, Guo F, Liu S, Chen Q. Structural insights into the molecular effects of the anthelmintics monepantel and betaine on the Caenorhabditis elegans acetylcholine receptor ACR-23. EMBO J 2024; 43:3787-3806. [PMID: 39009676 PMCID: PMC11377560 DOI: 10.1038/s44318-024-00165-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 06/27/2024] [Accepted: 06/28/2024] [Indexed: 07/17/2024] Open
Abstract
Anthelmintics are drugs used for controlling pathogenic helminths in animals and plants. The natural compound betaine and the recently developed synthetic compound monepantel are both anthelmintics that target the acetylcholine receptor ACR-23 and its homologs in nematodes. Here, we present cryo-electron microscopy structures of ACR-23 in apo, betaine-bound, and betaine- and monepantel-bound states. We show that ACR-23 forms a homo-pentameric channel, similar to some other pentameric ligand-gated ion channels (pLGICs). While betaine molecules are bound to the classical neurotransmitter sites in the inter-subunit interfaces in the extracellular domain, monepantel molecules are bound to allosteric sites formed in the inter-subunit interfaces in the transmembrane domain of the receptor. Although the pore remains closed in betaine-bound state, monepantel binding results in an open channel by wedging into the cleft between the transmembrane domains of two neighboring subunits, which causes dilation of the ion conduction pore. By combining structural analyses with site-directed mutagenesis, electrophysiology and in vivo locomotion assays, we provide insights into the mechanism of action of the anthelmintics monepantel and betaine.
Collapse
Affiliation(s)
- Fenglian Liu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Tianyu Li
- Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Department of Anesthesiology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, 201204, China
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Huihui Gong
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Fei Tian
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Yan Bai
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Haowei Wang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Chonglin Yang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Yang Li
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - Fei Guo
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, 200040, China.
| | - Sheng Liu
- Institute of Pediatrics, Shenzhen Children's Hospital, Shenzhen, Guangdong Province, 518026, China.
- Department of Infectious Diseases, Shenzhen Children's Hospital, Shenzhen, Guangdong Province, 518038, China.
| | - Qingfeng Chen
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, 650091, China.
| |
Collapse
|
3
|
Infield DT, Schene ME, Galpin JD, Ahern CA. Genetic Code Expansion for Mechanistic Studies in Ion Channels: An (Un)natural Union of Chemistry and Biology. Chem Rev 2024. [PMID: 39207057 DOI: 10.1021/acs.chemrev.4c00306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Ion channels play central roles in biology and human health by catalyzing the transmembrane flow of electrical charge. These proteins are ideal targets for genetic code expansion (GCE) methods because it is feasible to measure ion channel activity from miniscule amounts of protein and to analyze the resulting data via rigorous, established biophysical methods. In an ideal scenario, the encoding of synthetic, noncanonical amino acids via GCE allows the experimenter to ask questions inaccessible to traditional methods. For this reason, GCE has been successfully applied to a variety of ligand- and voltage-gated channels wherein extensive structural, functional, and pharmacological data exist. Here, we provide a comprehensive summary of GCE as applied to ion channels. We begin with an overview of the methods used to encode noncanonical amino acids in channels and then describe mechanistic studies wherein GCE was used for photochemistry (cross-linking; caged amino acids) and atomic mutagenesis (isosteric manipulation of charge and aromaticity; backbone mutation). Lastly, we cover recent advances in the encoding of fluorescent amino acids for the real-time study of protein conformational dynamics.
Collapse
Affiliation(s)
- Daniel T Infield
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, United States
| | - Miranda E Schene
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, United States
| | - Jason D Galpin
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, United States
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, United States
| |
Collapse
|
4
|
Gallino SL, Agüero L, Boffi JC, Schottlender G, Buonfiglio P, Dalamon V, Marcovich I, Carpaneto A, Craig PO, Plazas PV, Elgoyhen AB. Key role of the TM2-TM3 loop in calcium potentiation of the α9α10 nicotinic acetylcholine receptor. Cell Mol Life Sci 2024; 81:337. [PMID: 39120784 PMCID: PMC11335262 DOI: 10.1007/s00018-024-05381-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 07/09/2024] [Accepted: 07/23/2024] [Indexed: 08/10/2024]
Abstract
The α9α10 nicotinic cholinergic receptor (nAChR) is a ligand-gated pentameric cation-permeable ion channel that mediates synaptic transmission between descending efferent neurons and mechanosensory inner ear hair cells. When expressed in heterologous systems, α9 and α10 subunits can assemble into functional homomeric α9 and heteromeric α9α10 receptors. One of the differential properties between these nAChRs is the modulation of their ACh-evoked responses by extracellular calcium (Ca2+). While α9 nAChRs responses are blocked by Ca2+, ACh-evoked currents through α9α10 nAChRs are potentiated by Ca2+ in the micromolar range and blocked at millimolar concentrations. Using chimeric and mutant subunits, together with electrophysiological recordings under two-electrode voltage-clamp, we show that the TM2-TM3 loop of the rat α10 subunit contains key structural determinants responsible for the potentiation of the α9α10 nAChR by extracellular Ca2+. Moreover, molecular dynamics simulations reveal that the TM2-TM3 loop of α10 does not contribute to the Ca2+ potentiation phenotype through the formation of novel Ca2+ binding sites not present in the α9 receptor. These results suggest that the TM2-TM3 loop of α10 might act as a control element that facilitates the intramolecular rearrangements that follow ACh-evoked α9α10 nAChRs gating in response to local and transient changes of extracellular Ca2+ concentration. This finding might pave the way for the future rational design of drugs that target α9α10 nAChRs as otoprotectants.
Collapse
Affiliation(s)
- Sofia L Gallino
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ''Dr. Héctor N. Torres'' (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Lucía Agüero
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ''Dr. Héctor N. Torres'' (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Juan C Boffi
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ''Dr. Héctor N. Torres'' (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Epigenetics and Neurobiology Unit, European Molecular Biology Laboratory, Monterotondo, Italy
| | - Gustavo Schottlender
- Instituto de Cálculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Paula Buonfiglio
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ''Dr. Héctor N. Torres'' (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Viviana Dalamon
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ''Dr. Héctor N. Torres'' (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Irina Marcovich
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ''Dr. Héctor N. Torres'' (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Regeneron Pharmaceuticals, Inc. Tarrytown, 10591, NY, USA
| | - Agustín Carpaneto
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ''Dr. Héctor N. Torres'' (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Patricio O Craig
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
- Instituto de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (IQUIBICEN), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
| | - Paola V Plazas
- Instituto de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
| | - Ana B Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ''Dr. Héctor N. Torres'' (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
| |
Collapse
|
5
|
Bouchouireb Z, Olivier-Jimenez D, Jaunet-Lahary T, Thany SH, Le Questel JY. Navigating the complexities of docking tools with nicotinic receptors and acetylcholine binding proteins in the realm of neonicotinoids. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 281:116582. [PMID: 38905934 DOI: 10.1016/j.ecoenv.2024.116582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 05/30/2024] [Accepted: 06/09/2024] [Indexed: 06/23/2024]
Abstract
Molecular docking, pivotal in predicting small-molecule ligand binding modes, struggles with accurately identifying binding conformations and affinities. This is particularly true for neonicotinoids, insecticides whose impacts on ecosystems require precise molecular interaction modeling. This study scrutinizes the effectiveness of prominent docking software (Ledock, ADFR, Autodock Vina, CDOCKER) in simulating interactions of environmental chemicals, especially neonicotinoid-like molecules with nicotinic acetylcholine receptors (nAChRs) and acetylcholine binding proteins (AChBPs). We aimed to assess the accuracy and reliability of these tools in reproducing crystallographic data, focusing on semi-flexible and flexible docking approaches. Our analysis identified Ledock as the most accurate in semi-flexible docking, while Autodock Vina with Vinardo scoring function proved most reliable. However, no software consistently excelled in both accuracy and reliability. Additionally, our evaluation revealed that none of the tools could establish a clear correlation between docking scores and experimental dissociation constants (Kd) for neonicotinoid-like compounds. In contrast, a strong correlation was found with drug-like compounds, bringing to light a bias in considered software towards pharmaceuticals, thus limiting their applicability to environmental chemicals. The comparison between semi-flexible and flexible docking revealed that the increased computational complexity of the latter did not result in enhanced accuracy. In fact, the higher computational cost of flexible docking with its lack of enhanced predictive accuracy, rendered this approach useless for this class of compounds. Conclusively, our findings emphasize the need for continued development of docking methodologies, particularly for environmental chemicals. This study not only illuminates current software capabilities but also underscores the urgency for advancements in computational molecular docking as it is a relevant tool to environmental sciences.
Collapse
Affiliation(s)
| | - Damien Olivier-Jimenez
- Leiden University Medical Center, Center for Proteomics and Metabolomics, Albinusdreef 2, Leiden 2333ZA, Netherlands
| | | | - Steeve H Thany
- Université d'Orléans, Physiology, Ecology and Environment (P2E) laboratory USC INRAE 1328, Orléans 45067, France; Institut universitaire de France (IUF), 1 rue Descartes 75005 Paris, France
| | | |
Collapse
|
6
|
Cecchini M, Corringer PJ, Changeux JP. The Nicotinic Acetylcholine Receptor and Its Pentameric Homologs: Toward an Allosteric Mechanism of Signal Transduction at the Atomic Level. Annu Rev Biochem 2024; 93:339-366. [PMID: 38346274 DOI: 10.1146/annurev-biochem-030122-033116] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
The nicotinic acetylcholine receptor has served, since its biochemical identification in the 1970s, as a model of an allosteric ligand-gated ion channel mediating signal transition at the synapse. In recent years, the application of X-ray crystallography and high-resolution cryo-electron microscopy, together with molecular dynamic simulations of nicotinic receptors and homologs, have opened a new era in the understanding of channel gating by the neurotransmitter. They reveal, at atomic resolution, the diversity and flexibility of the multiple ligand-binding sites, including recently discovered allosteric modulatory sites distinct from the neurotransmitter orthosteric site, and the conformational dynamics of the activation process as a molecular switch linking these multiple sites. The model emerging from these studies paves the way for a new pharmacology based, first, upon the occurrence of an original mode of indirect allosteric modulation, distinct from a steric competition for a single and rigid binding site, and second, the design of drugs that specifically interact with privileged conformations of the receptor such as agonists, antagonists, and desensitizers. Research on nicotinic receptors is still at the forefront of understanding the mode of action of drugs on the nervous system.
Collapse
Affiliation(s)
- Marco Cecchini
- Institut de Chimie de Strasbourg, CNRS UMR 7177, Université de Strasbourg, Strasbourg, France
| | - Pierre-Jean Corringer
- Channel Receptors Unit, Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Paris, France
| | - Jean-Pierre Changeux
- Department of Neuroscience, Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Paris, France;
| |
Collapse
|
7
|
Li H, Teng J, Hibbs RE. Structural switch in acetylcholine receptors in developing muscle. Nature 2024; 632:1174-1180. [PMID: 39085615 DOI: 10.1038/s41586-024-07774-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 07/02/2024] [Indexed: 08/02/2024]
Abstract
During development, motor neurons originating in the brainstem and spinal cord form elaborate synapses with skeletal muscle fibres1. These neurons release acetylcholine (ACh), which binds to nicotinic ACh receptors (AChRs) on the muscle, initiating contraction. Two types of AChR are present in developing muscle cells, and their differential expression serves as a hallmark of neuromuscular synapse maturation2-4. The structural principles underlying the switch from fetal to adult muscle receptors are unknown. Here, we present high-resolution structures of both fetal and adult muscle nicotinic AChRs, isolated from bovine skeletal muscle in developmental transition. These structures, obtained in the absence and presence of ACh, provide a structural context for understanding how fetal versus adult receptor isoforms are tuned for synapse development versus the all-or-none signalling required for high-fidelity skeletal muscle contraction. We find that ACh affinity differences are driven by binding site access, channel conductance is tuned by widespread surface electrostatics and open duration changes result from intrasubunit interactions and structural flexibility. The structures further reveal pathogenic mechanisms underlying congenital myasthenic syndromes.
Collapse
Affiliation(s)
- Huanhuan Li
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
| | - Jinfeng Teng
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA
| | - Ryan E Hibbs
- Department of Neurobiology, University of California San Diego, La Jolla, CA, USA.
- Department of Pharmacology, University of California San Diego, La Jolla, CA, USA.
| |
Collapse
|
8
|
Mazzaferro S, Kang G, Natarajan K, Hibbs RE, Sine SM. Structural bases for stoichiometry-selective calcium potentiation of a neuronal nicotinic receptor. Br J Pharmacol 2024; 181:1973-1992. [PMID: 38454578 DOI: 10.1111/bph.16321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 03/09/2024] Open
Abstract
BACKGROUND AND PURPOSE α4β2 nicotinic acetylcholine (nACh) receptors assemble in two stoichiometric forms, one of which is potentiated by calcium. The sites of calcium binding that underpin potentiation are not known. EXPERIMENTAL APPROACH To identify calcium binding sites, we applied cryo-electron microscopy (cryo-EM) and molecular dynamics (MD) simulations to each stoichiometric form of the α4β2 nACh receptor in the presence of calcium ions. To test whether the identified calcium sites are linked to potentiation, we generated mutants of anionic residues at the sites, expressed wild type and mutant receptors in clonal mammalian fibroblasts, and recorded ACh-elicited single-channel currents with or without calcium. KEY RESULTS Both cryo-EM and MD simulations show calcium bound to a site between the extracellular and transmembrane domains of each α4 subunit (ECD-TMD site). Substituting alanine for anionic residues at the ECD-TMD site abolishes stoichiometry-selective calcium potentiation, as monitored by single-channel patch clamp electrophysiology. Additionally, MD simulation reveals calcium association at subunit interfaces within the extracellular domain. Substituting alanine for anionic residues at the ECD sites reduces or abolishes stoichiometry-selective calcium potentiation. CONCLUSIONS AND IMPLICATIONS Stoichiometry-selective calcium potentiation of the α4β2 nACh receptor is achieved by calcium association with topographically distinct sites framed by anionic residues within the α4 subunit and between the α4 and β2 subunits. Stoichiometry-selective calcium potentiation could result from the greater number of calcium sites in the stoichiometric form with three rather than two α4 subunits. The results are relevant to modulation of signalling via α4β2 nACh receptors in physiological and pathophysiological conditions.
Collapse
Affiliation(s)
- Simone Mazzaferro
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
- Wellcome Trust - Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, UK
- Wellcome Trust - Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Guipeun Kang
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kathiresan Natarajan
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurobiology, University of California San Diego, La Jolla, California, USA
| | - Steven M Sine
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota, USA
- Department of Neurology, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| |
Collapse
|
9
|
Kaiser J, Gertzen CGW, Bernauer T, Nitsche V, Höfner G, Niessen KV, Seeger T, Paintner FF, Wanner KT, Steinritz D, Worek F, Gohlke H. Identification of ligands binding to MB327-PAM-1, a binding pocket relevant for resensitization of nAChRs. Toxicol Lett 2024; 398:91-104. [PMID: 38768836 DOI: 10.1016/j.toxlet.2024.05.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 04/13/2024] [Accepted: 05/17/2024] [Indexed: 05/22/2024]
Abstract
Desensitization of nicotinic acetylcholine receptors (nAChRs) can be induced by overstimulation with acetylcholine (ACh) caused by an insufficient degradation of ACh after poisoning with organophosphorus compounds (OPCs). Currently, there is no generally applicable treatment for OPC poisoning that directly targets the desensitized nAChR. The bispyridinium compound MB327, an allosteric modulator of nAChR, has been shown to act as a resensitizer of nAChRs, indicating that drugs binding directly to nAChRs can have beneficial effects after OPC poisoning. However, MB327 also acts as an inhibitor of nAChRs at higher concentrations and can thus not be used for OPC poisoning treatment. Consequently, novel, more potent resensitizers are required. To successfully design novel ligands, the knowledge of the binding site is of utmost importance. Recently, we performed in silico studies to identify a new potential binding site of MB327, MB327-PAM-1, for which a more affine ligand, UNC0646, has been described. In this work, we performed ligand-based screening approaches to identify novel analogs of UNC0646 to help further understand the structure-affinity relationship of this compound class. Furthermore, we used structure-based screenings and identified compounds representing four new chemotypes binding to MB327-PAM-1. One of these compounds, cycloguanil, is the active metabolite of the antimalaria drug proguanil and shows a higher affinity towards MB327-PAM-1 than MB327. Furthermore, cycloguanil can reestablish the muscle force in soman-inhibited rat muscles. These results can act as a starting point to develop more potent resensitizers of nAChR and to close the gap in the treatment after OPC poisoning.
Collapse
Affiliation(s)
- Jesko Kaiser
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Christoph G W Gertzen
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tamara Bernauer
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Valentin Nitsche
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Georg Höfner
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Karin V Niessen
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Franz F Paintner
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Klaus T Wanner
- Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Dirk Steinritz
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich, Jülich, Germany.
| |
Collapse
|
10
|
Wang Y, Qiu L, Wang B, Guan Z, Dong Z, Zhang J, Cao S, Yang L, Wang B, Gong Z, Zhang L, Ma W, Liu Z, Zhang D, Wang G, Yin P. Structural basis for odorant recognition of the insect odorant receptor OR-Orco heterocomplex. Science 2024; 384:1453-1460. [PMID: 38870272 DOI: 10.1126/science.adn6881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 05/29/2024] [Indexed: 06/15/2024]
Abstract
Insects detect and discriminate a diverse array of chemicals using odorant receptors (ORs), which are ligand-gated ion channels comprising a divergent odorant-sensing OR and a conserved odorant receptor co-receptor (Orco). In this work, we report structures of the ApOR5-Orco heterocomplex from the pea aphid Acyrthosiphon pisum alone and bound to its known activating ligand, geranyl acetate. In these structures, three ApOrco subunits serve as scaffold components that cannot bind the ligand and remain relatively unchanged. Upon ligand binding, the pore-forming helix S7b of ApOR5 shifts outward from the central pore axis, causing an asymmetrical pore opening for ion influx. Our study provides insights into odorant recognition and channel gating of the OR-Orco heterocomplex and offers structural resources to support development of innovative insecticides and repellents for pest control.
Collapse
Affiliation(s)
- Yidong Wang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Synthetic Biology Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Liang Qiu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Bing Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zeyuan Guan
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhi Dong
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Jie Zhang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Song Cao
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Synthetic Biology Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Lulu Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Bo Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zhou Gong
- Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Liwei Zhang
- College of Grassland Science and Technology, China Agricultural University, Beijing 100193, China
| | - Weihua Ma
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhu Liu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Delin Zhang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Guirong Wang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Synthetic Biology Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Ping Yin
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| |
Collapse
|
11
|
Nemecz D, Nowak WA, Nemecz Á. VHH Nanobody Versatility against Pentameric Ligand-Gated Ion Channels. J Med Chem 2024; 67:8502-8518. [PMID: 38829690 PMCID: PMC11181324 DOI: 10.1021/acs.jmedchem.4c00231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/17/2024] [Accepted: 05/20/2024] [Indexed: 06/05/2024]
Abstract
Pentameric ligand-gated ion channels provide rapid chemical-electrical signal transmission between cells in the central and peripheral nervous system. Their dysfunction is associated with many nervous system disorders. They are composed of five identical (homomeric receptors) or homologous (heteromeric receptors) subunits. VHH nanobodies, or single-chain antibodies, are the variable domain, VHH, of antibodies that are composed of the heavy chain only from camelids. Their unique structure results in many specific biochemical and biophysical properties that make them an excellent alternative to conventional antibodies. This Perspective explores the published VHH nanobodies which have been isolated against pentameric ligand-gated ion channel subfamilies. It outlines the genetic and chemical modifications available to alter nanobody function. An assessment of the available functional and structural data indicate that it is feasible to create therapeutic agents and impart, through their modification, a given desired modulatory effect of its target receptor for current stoichiometric-specific VHH nanobodies.
Collapse
Affiliation(s)
- Dorota Nemecz
- Biochemistry
Department, Nicolaus Copernicus University
in Torun, 87-100 Torun, Poland
| | - Weronika A. Nowak
- Biochemistry
Department, Nicolaus Copernicus University
in Torun, 87-100 Torun, Poland
| | - Ákos Nemecz
- Biochemistry
Department, Nicolaus Copernicus University
in Torun, 87-100 Torun, Poland
| |
Collapse
|
12
|
Santis GD, Okura Y, Hirata K, Ishiuchi SI, Fujii M, Xantheas SS. Affinity of Nicotinoids to a Model Nicotinic Acetylcholine Receptor (nAChR) Binding Pocket in the Human Brain. J Phys Chem B 2024; 128:4577-4589. [PMID: 38696590 DOI: 10.1021/acs.jpcb.3c07919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2024]
Abstract
The binding affinity of nicotinoids to the binding residues of the α4β2 variant of the nicotinic acetylcholine receptor (nAChR) was identified as a strong predictor of the nicotinoid's addictive character. Using ab initio calculations for model binding pockets of increasing size composed of 3, 6, and 14 amino acids (3AA, 6AA, and 14AA) that are derived from the crystal structure, the differences in binding affinity of 6 nicotinoids, namely, nicotine (NIC), nornicotine (NOR), anabasine (ANB), anatabine (ANT), myosmine (MYO), and cotinine (COT) were correlated to their previously reported doses required for increases in intracranial self-stimulation (ICSS) thresholds, a metric for their addictive function. By employing the many-body decomposition, the differences in the binding affinities of the various nicotinoids could be attributed mainly to the proton exchange energy between the pyridine and non-pyridine rings of the nicotinoids and the interactions between them and a handful of proximal amino acids, namely Trp156, Trpβ57, Tyr100, and Tyr204. Interactions between the guest nicotinoid and the amino acids of the binding pocket were found to be mainly classical in nature, except for those between the nicotinoid and Trp156. The larger pockets were found to model binding structures more accurately and predicted the addictive character of all nicotinoids, while smaller models, which are more computationally feasible, would only predict the addictive character of nicotinoids that are similar to nicotine. The present study identifies the binding affinity of the guest nicotinoid to the host binding pocket as a strong descriptor of the nicotinoid's addiction potential, and as such it can be employed as a fast-screening technique for the potential addiction of nicotine analogs.
Collapse
Affiliation(s)
- Garrett D Santis
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Yuika Okura
- Department of Chemistry, School of Science, Tokyo Intitute of Technology; 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152855, Japan
| | - Keisuke Hirata
- Department of Chemistry, School of Science, Tokyo Intitute of Technology; 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152855, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Shun-Ichi Ishiuchi
- Department of Chemistry, School of Science, Tokyo Intitute of Technology; 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152855, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
- Research and Development Initiative, Chuo University, Tokyo 112-8551, Japan
| | - Sotiris S Xantheas
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, MS K1-83, P.O. Box 999, Richland, Washington 99352, United States
| |
Collapse
|
13
|
Msekela DJ, Sine SM. Pathogenic residue insertion in neuronal nicotinic receptor alters intra- and inter-subunit interactions that tune channel gating. J Biol Chem 2024; 300:107266. [PMID: 38583864 PMCID: PMC11067541 DOI: 10.1016/j.jbc.2024.107266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/19/2024] [Accepted: 03/30/2024] [Indexed: 04/09/2024] Open
Abstract
We describe molecular-level functional changes in the α4β2 nicotinic acetylcholine receptor by a leucine residue insertion in the M2 transmembrane domain of the α4 subunit associated with sleep-related hyperkinetic epilepsy. Measurements of agonist-elicited single-channel currents reveal the primary effect is to stabilize the open channel state, while the secondary effect is to promote reopening of the channel. These dual effects prolong the durations of bursts of channel openings equally for the two major stoichiometric forms of the receptor, (α4)2(β2)3 and (α4)3(β2)2, indicating the functional impact is independent of mutant copy number per receptor. Altering the location of the residue insertion within M2 shows that functionally pivotal structures are confined to a half turn of the M2 α-helix. Residue substitutions within M2 and surrounding α-helices reveal that both intrasubunit and intersubunit interactions mediate the increase in burst duration. These interactions impacting burst duration depend linearly on the size and hydrophobicity of the substituting residue. Together, the results reveal a novel structural region of the α4β2 nicotinic acetylcholine receptor in which interhelical interactions tune the stability of the open channel state.
Collapse
Affiliation(s)
- Deborah J Msekela
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA
| | - Steven M Sine
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA; Department of Neurology, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.
| |
Collapse
|
14
|
Ananchenko A, Gao RY, Dehez F, Baenziger JE. State-dependent binding of cholesterol and an anionic lipid to the muscle-type Torpedo nicotinic acetylcholine receptor. Commun Biol 2024; 7:437. [PMID: 38600247 PMCID: PMC11006840 DOI: 10.1038/s42003-024-06106-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
The ability of the Torpedo nicotinic acetylcholine receptor (nAChR) to undergo agonist-induced conformational transitions requires the presence of cholesterol and/or anionic lipids. Here we use recently solved structures along with multiscale molecular dynamics simulations to examine lipid binding to the nAChR in bilayers that have defined effects on nAChR function. We examine how phosphatidic acid and cholesterol, lipids that support conformational transitions, individually compete for binding with phosphatidylcholine, a lipid that does not. We also examine how the two lipids work synergistically to stabilize an agonist-responsive nAChR. We identify rapidly exchanging lipid binding sites, including both phospholipid sites with a high affinity for phosphatidic acid and promiscuous cholesterol binding sites in the grooves between adjacent transmembrane α-helices. A high affinity cholesterol site is confirmed in the inner leaflet framed by a key tryptophan residue on the MX α-helix. Our data provide insight into the dynamic nature of lipid-nAChR interactions and set the stage for a detailed understanding of the mechanisms by which lipids facilitate nAChR function at the neuromuscular junction.
Collapse
Affiliation(s)
- Anna Ananchenko
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Rui Yan Gao
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - François Dehez
- CNRS, LPCT, Université de Lorraine, F-54000 Nancy, France.
| | - John E Baenziger
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.
| |
Collapse
|
15
|
Appiani R, Viscarra F, Biggin PC, Bermudez I, Giraudo A, Pallavicini M, Bolchi C. Selective Potentiation of the (α4) 3(β2) 2 Nicotinic Acetylcholine Receptor Response by NS9283 Analogues. ACS Chem Neurosci 2024; 15:1501-1514. [PMID: 38511291 DOI: 10.1021/acschemneuro.3c00797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024] Open
Abstract
NS9283, 3-(3-pyridyl)-5-(3-cyanophenyl)-1,2,4-oxadiazole, is a selective positive allosteric modulator of (α4)3(β2)2 nicotinic acetylcholine receptors (nAChRs). It has good subtype selective therapeutic potential afforded by its specific binding to the unique α4-α4 subunit interface present in the (α4)3(β2)2 nAChR. However, there is currently a lack of structure activity relationship (SAR) studies aimed at developing a class of congeners endowed with the same profile of activity that can help consolidate the druggability of the α4-α4 subunit interface. In this study, new NS9283 analogues were designed, synthesized, and characterized for their ability to selectively potentiate the ACh activity at heterologous (α4)3(β2)2 nAChRs vs nAChR subtypes (α4)2(β2)3, α5α4β2, and α7. With few exceptions, all the NS9283 analogues exerted positive modulation of the (α4)3(β2)2 nAChR ACh-evoked responses. Above all, those modified at the 3-cyanophenyl moiety by replacement with 3-nitrophenyl (4), 4-cyanophenyl (10), and N-formyl-4-piperidinyl (20) showed the same efficacy as NS9283, although with lower potency. Molecular dynamics simulations of NS9283 and some selected analogues highlighted consistency between potentiation activity and pose of the ligand inside the α4-α4 site with the main interaction being with the complementary (-) side and induction of a significant conformational change of the Trp156 residue in the principal (+) side.
Collapse
Affiliation(s)
- Rebecca Appiani
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, via Mangiagalli 25, Milano I-20133, Italy
| | - Franco Viscarra
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
- Structural Bioinformatics and Computational Biochemistry Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Philip C Biggin
- Structural Bioinformatics and Computational Biochemistry Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Isabel Bermudez
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
| | - Alessandro Giraudo
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, via Mangiagalli 25, Milano I-20133, Italy
| | - Marco Pallavicini
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, via Mangiagalli 25, Milano I-20133, Italy
| | - Cristiano Bolchi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, via Mangiagalli 25, Milano I-20133, Italy
| |
Collapse
|
16
|
Son L, Kost V, Maiorov V, Sukhov D, Arkhangelskaya P, Ivanov I, Kudryavtsev D, Siniavin A, Utkin Y, Kasheverov I. Efficient Expression in Leishmania tarentolae (LEXSY) of the Receptor-Binding Domain of the SARS-CoV-2 S-Protein and the Acetylcholine-Binding Protein from Lymnaea stagnalis. Molecules 2024; 29:943. [PMID: 38474455 DOI: 10.3390/molecules29050943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 01/31/2024] [Accepted: 02/15/2024] [Indexed: 03/14/2024] Open
Abstract
Leishmania tarentolae (LEXSY) system is an inexpensive and effective expression approach for various research and medical purposes. The stated advantages of this system are the possibility of obtaining the soluble product in the cytoplasm, a high probability of correct protein folding with a full range of post-translational modifications (including uniform glycosylation), and the possibility of expressing multi-subunit proteins. In this paper, a LEXSY expression system has been employed for obtaining the receptor binding domain (RBD) of the spike-protein of the SARS-CoV-2 virus and the homopentameric acetylcholine-binding protein (AChBP) from Lymnaea stagnalis. RBD is actively used to obtain antibodies against the virus and in various scientific studies on the molecular mechanisms of the interaction of the virus with host cell targets. AChBP represents an excellent structural model of the ligand-binding extracellular domain of all subtypes of nicotinic acetylcholine receptors (nAChRs). Both products were obtained in a soluble glycosylated form, and their structural and functional characteristics were compared with those previously described.
Collapse
Affiliation(s)
- Lina Son
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Vladimir Kost
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Valery Maiorov
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Dmitry Sukhov
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Polina Arkhangelskaya
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Igor Ivanov
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Denis Kudryavtsev
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Andrei Siniavin
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
- Ivanovsky Institute of Virology, N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, 123098 Moscow, Russia
| | - Yuri Utkin
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Igor Kasheverov
- Department of Molecular Bases of Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| |
Collapse
|
17
|
Okura Y, Santis GD, Hirata K, Melissas VS, Ishiuchi SI, Fujii M, Xantheas SS. Switching of Protonation Sites in Hydrated Nicotine via a Grotthuss Mechanism. J Am Chem Soc 2024; 146:3023-3030. [PMID: 38261007 DOI: 10.1021/jacs.3c08922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The switching of the protonation sites in hydrated nicotine, probed by experimental infrared (IR) spectroscopy and theoretical ab initio calculations, is facilitated via a Grotthuss instead of a bimolecular proton transfer (vehicle) mechanism at the experimental temperature (T = 130 K) as unambiguously confirmed by experiments with deuterated water. In contrast, the bimolecular vehicle mechanism is preferred at higher temperatures (T = 300 K) as determined by theory. The Grotthuss mechanism for the concerted proton transfer results in the production of nicotine's bioactive and addictive pyrrolidine-protonated (Pyrro-H+) protomer with just 5 water molecules. Theoretical analysis suggests that the concerted proton transfer occurs via hydrogen-bonded bridges consisting of a 3 water molecule "core" that connects the pyridine protonated (Pyri-H+) with the pyrrolidine-protonated (Pyrro-H+) protomers. Additional water molecules attached as acceptors to the hydrogen-bonded "core" bridge result in lowering the reaction barrier of the concerted proton transfer down to less than 6 kcal/mol, which is consistent with the experimental observations.
Collapse
Affiliation(s)
- Yuika Okura
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Garrett D Santis
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Keisuke Hirata
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | | | - Shun-Ichi Ishiuchi
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Sotiris S Xantheas
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
- Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington 99352, United States
| |
Collapse
|
18
|
Bergh C, Rovšnik U, Howard R, Lindahl E. Discovery of lipid binding sites in a ligand-gated ion channel by integrating simulations and cryo-EM. eLife 2024; 12:RP86016. [PMID: 38289224 PMCID: PMC10945520 DOI: 10.7554/elife.86016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024] Open
Abstract
Ligand-gated ion channels transduce electrochemical signals in neurons and other excitable cells. Aside from canonical ligands, phospholipids are thought to bind specifically to the transmembrane domain of several ion channels. However, structural details of such lipid contacts remain elusive, partly due to limited resolution of these regions in experimental structures. Here, we discovered multiple lipid interactions in the channel GLIC by integrating cryo-electron microscopy and large-scale molecular simulations. We identified 25 bound lipids in the GLIC closed state, a conformation where none, to our knowledge, were previously known. Three lipids were associated with each subunit in the inner leaflet, including a buried interaction disrupted in mutant simulations. In the outer leaflet, two intrasubunit sites were evident in both closed and open states, while a putative intersubunit site was preferred in open-state simulations. This work offers molecular details of GLIC-lipid contacts particularly in the ill-characterized closed state, testable hypotheses for state-dependent binding, and a multidisciplinary strategy for modeling protein-lipid interactions.
Collapse
Affiliation(s)
- Cathrine Bergh
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
| | - Urška Rovšnik
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
| | - Rebecca Howard
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
| | - Erik Lindahl
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
| |
Collapse
|
19
|
Barrantes FJ. Modulation of a rapid neurotransmitter receptor-ion channel by membrane lipids. Front Cell Dev Biol 2024; 11:1328875. [PMID: 38274273 PMCID: PMC10808158 DOI: 10.3389/fcell.2023.1328875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 12/26/2023] [Indexed: 01/27/2024] Open
Abstract
Membrane lipids modulate the proteins embedded in the bilayer matrix by two non-exclusive mechanisms: direct or indirect. The latter comprise those effects mediated by the physicochemical state of the membrane bilayer, whereas direct modulation entails the more specific regulatory effects transduced via recognition sites on the target membrane protein. The nicotinic acetylcholine receptor (nAChR), the paradigm member of the pentameric ligand-gated ion channel (pLGIC) superfamily of rapid neurotransmitter receptors, is modulated by both mechanisms. Reciprocally, the nAChR protein exerts influence on its surrounding interstitial lipids. Folding, conformational equilibria, ligand binding, ion permeation, topography, and diffusion of the nAChR are modulated by membrane lipids. The knowledge gained from biophysical studies of this prototypic membrane protein can be applied to other neurotransmitter receptors and most other integral membrane proteins.
Collapse
Affiliation(s)
- Francisco J. Barrantes
- Biomedical Research Institute (BIOMED), Catholic University of Argentina (UCA)–National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
| |
Collapse
|
20
|
Yin H, Rosas R, Viel S, Giorgi M, Monnier V, Charles L, Siri D, Gigmes D, Nassar Y, Chevallier F, Bucher C, Wang R, Kermagoret A, Bardelang D. Internal Dynamics and Modular Peripheral Binding in Stimuli-Responsive 3 : 2 Host:Guest Complexes. Angew Chem Int Ed Engl 2024; 63:e202315985. [PMID: 38009627 DOI: 10.1002/anie.202315985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 11/23/2023] [Accepted: 11/24/2023] [Indexed: 11/29/2023]
Abstract
Now that the chemistry of 1 : 1 host:guest complexes is well-established, it is surprising to note that higher stoichiometry (oligomeric) complexes, especially those with excess host, remain largely unexplored. Yet, proteins tend to oligomerize, affording new functions for cell machinery. Here, we show that cucurbit[n]uril (CB[n]) macrocycles combined with symmetric, linear di-viologens form unusual 3 : 2 host:guest complexes exhibiting remarkable dynamic properties, host self-sorting, and external ring-translocation. These results highlight the structural tunability of cucurbit[8]uril (CB[8]) based 3 : 2 host:guest complexes in water and their responsiveness toward several stimuli (chemicals, pH, redox).
Collapse
Affiliation(s)
- Hang Yin
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau, China
| | - Roselyne Rosas
- Aix Marseille Univ, CNRS, Centrale Marseille, FSCM, Spectropole, Marseille, France
| | - Stéphane Viel
- Aix Marseille Univ, CNRS, ICR, AMUtech, Marseille, France
- Institut Universitaire de France, 75005, Paris, France
| | - Michel Giorgi
- Aix Marseille Univ, CNRS, Centrale Marseille, FSCM, Spectropole, Marseille, France
| | - Valerie Monnier
- Aix Marseille Univ, CNRS, Centrale Marseille, FSCM, Spectropole, Marseille, France
| | | | - Didier Siri
- Aix Marseille Univ, CNRS, ICR, AMUtech, Marseille, France
| | - Didier Gigmes
- Aix Marseille Univ, CNRS, ICR, AMUtech, Marseille, France
| | - Youssef Nassar
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Laboratoire de Chimie, 69342, Lyon, France
| | - Floris Chevallier
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Laboratoire de Chimie, 69342, Lyon, France
| | - Christophe Bucher
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Laboratoire de Chimie, 69342, Lyon, France
| | - Ruibing Wang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau, China
| | | | | |
Collapse
|
21
|
George AA, John SJ, Lucero LM, Eaton JB, Jaiswal E, Christensen SB, Gajewiak J, Watkins M, Cao Y, Olivera BM, Im W, McIntosh JM, Whiteaker P. Analogs of α-conotoxin PnIC selectively inhibit α7β2- over α7-only subtype nicotinic acetylcholine receptors via a novel allosteric mechanism. FASEB J 2024; 38:e23374. [PMID: 38161283 PMCID: PMC10782225 DOI: 10.1096/fj.202302079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 12/01/2023] [Indexed: 01/03/2024]
Abstract
This study was undertaken to identify and characterize the first ligands capable of selectively identifying nicotinic acetylcholine receptors containing α7 and β2 subunits (α7β2-nAChR subtype). Basal forebrain cholinergic neurons express α7β2-nAChR. Here, they appear to mediate neuronal dysfunction induced by the elevated levels of oligomeric amyloid-β associated with early Alzheimer's disease. Additional work indicates that α7β2-nAChR are expressed across several further critically important cholinergic and GABAergic neuronal circuits within the central nervous system. Further studies, however, are significantly hindered by the inability of currently available ligands to distinguish heteromeric α7β2-nAChR from the closely related and more widespread homomeric α7-only-nAChR subtype. Functional screening using two-electrode voltage-clamp electrophysiology identified a family of α7β2-nAChR-selective analogs of α-conotoxin PnIC (α-CtxPnIC). A combined electrophysiology, functional kinetics, site-directed mutagenesis, and molecular dynamics approach was used to further characterize the α7β2-nAChR selectivity and site of action of these α-CtxPnIC analogs. We determined that α7β2-nAChR selectivity of α-CtxPnIC analogs arises from interactions at a site distinct from the orthosteric agonist-binding site shared between α7β2- and α7-only-nAChR. As numerous previously identified α-Ctx ligands are competitive antagonists of orthosteric agonist-binding sites, this study profoundly expands the scope of use of α-Ctx ligands (which have already provided important nAChR research and translational breakthroughs). More immediately, analogs of α-CtxPnIC promise to enable, for the first time, both comprehensive mapping of the distribution of α7β2-nAChR and detailed investigations of their physiological roles.
Collapse
Affiliation(s)
- Andrew A. George
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
| | - Sabin J. John
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
- Department of Life SciencesUniversity of BathBathUK
| | - Linda M. Lucero
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | - J. Brek Eaton
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | - Ekta Jaiswal
- Department of NeurobiologyBarrow Neurological InstitutePhoenixArizonaUSA
| | | | - Joanna Gajewiak
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Maren Watkins
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
| | - Yiwei Cao
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | | | - Wonpil Im
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - J. Michael McIntosh
- School of Biological SciencesUniversity of UtahSalt Lake CityUtahUSA
- George E. Wahlen Veterans Affairs Medical CenterSalt Lake CityUtahUSA
- Department of PsychiatryUniversity of UtahSalt Lake CityUtahUSA
| | - Paul Whiteaker
- Department of Pharmacology and Toxicology, School of MedicineVirginia Commonwealth UniversityRichmondVirginiaUSA
| |
Collapse
|
22
|
Raisch T, Raunser S. The modes of action of ion-channel-targeting neurotoxic insecticides: lessons from structural biology. Nat Struct Mol Biol 2023; 30:1411-1427. [PMID: 37845413 DOI: 10.1038/s41594-023-01113-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 08/31/2023] [Indexed: 10/18/2023]
Abstract
Insecticides are indispensable tools for plant protection in modern agriculture. Despite having highly heterogeneous structures, many neurotoxic insecticides use similar principles to inhibit or deregulate neuronal ion channels. Insecticides targeting pentameric ligand-gated channels are structural mimetics of neurotransmitters or manipulate and deregulate the proteins. Those binding to (pseudo-)tetrameric voltage-gated(-like) channels, on the other hand, are natural or synthetic compounds that directly block the ion-conducting pore or prevent conformational changes in the transmembrane domain necessary for opening and closing the pore. The use of a limited number of inhibition mechanisms can be problematic when resistances arise and become more widespread. Therefore, there is a rising interest in the development of insecticides with novel mechanisms that evade resistance and are pest-insect-specific. During the last decade, most known insecticide targets, many with bound compounds, have been structurally characterized, bringing the rational design of novel classes of agrochemicals within closer reach than ever before.
Collapse
Affiliation(s)
- Tobias Raisch
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
| |
Collapse
|
23
|
Prevost MS, Barilone N, Dejean de la Bâtie G, Pons S, Ayme G, England P, Gielen M, Bontems F, Pehau-Arnaudet G, Maskos U, Lafaye P, Corringer PJ. An original potentiating mechanism revealed by the cryo-EM structures of the human α7 nicotinic receptor in complex with nanobodies. Nat Commun 2023; 14:5964. [PMID: 37749098 PMCID: PMC10520083 DOI: 10.1038/s41467-023-41734-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 09/15/2023] [Indexed: 09/27/2023] Open
Abstract
The human α7 nicotinic receptor is a pentameric channel mediating cellular and neuronal communication. It has attracted considerable interest in designing ligands for the treatment of neurological and psychiatric disorders. To develop a novel class of α7 ligands, we recently generated two nanobodies named E3 and C4, acting as positive allosteric modulator and silent allosteric ligand, respectively. Here, we solved the cryo-electron microscopy structures of the nanobody-receptor complexes. E3 and C4 bind to a common epitope involving two subunits at the apex of the receptor. They form by themselves a symmetric pentameric assembly that extends the extracellular domain. Unlike C4, the binding of E3 drives an agonist-bound conformation of the extracellular domain in the absence of an orthosteric agonist, and mutational analysis shows a key contribution of an N-linked sugar moiety in mediating E3 potentiation. The nanobody E3, by remotely controlling the global allosteric conformation of the receptor, implements an original mechanism of regulation that opens new avenues for drug design.
Collapse
Affiliation(s)
- Marie S Prevost
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France.
| | - Nathalie Barilone
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
| | | | - Stéphanie Pons
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Integrative Neurobiology of Cholinergic Systems Unit, Paris, France
| | - Gabriel Ayme
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France
| | - Patrick England
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Molecular Biophysics Platform, Paris, France
| | - Marc Gielen
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
- Sorbonne Université, Paris, France
| | - François Bontems
- Institut Pasteur, Université Paris Cité, CNRS UMR 3569, Structural Virology Unit, Paris, France
- Institut de Chimie des Substances Naturelles, Centre National de la Recherche Scientifique, Université Paris Saclay, Gif-sur-Yvette, France
| | - Gérard Pehau-Arnaudet
- Institut Pasteur, Université Paris Cité, Ultrastructural Bioimaging Core Facility, Paris, France
| | - Uwe Maskos
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Integrative Neurobiology of Cholinergic Systems Unit, Paris, France
| | - Pierre Lafaye
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France
| | - Pierre-Jean Corringer
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France.
| |
Collapse
|
24
|
Zhou L, Dau V, Jensen AA. Discovery of a Novel Class of Benzimidazole-Based Nicotinic Acetylcholine Receptor Modulators: Positive and Negative Modulation Arising from Overlapping Allosteric Sites. J Med Chem 2023; 66:12586-12601. [PMID: 37650525 DOI: 10.1021/acs.jmedchem.3c01185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Here, we present the discovery of a novel class of benzimidazole-based allosteric modulators of nicotinic acetylcholine receptors (nAChRs). The modulators were developed based on a compound (1) exhibiting positive modulatory activity at α4β2 nAChR in a compound library screening by functional characterization of 100 analogues of 1 at nAChRs. Two distinct series of positive and negative allosteric modulators (PAMs and NAMs, respectively) comprising benzimidazole as a shared structural moiety emerged from this SAR study. The PAMs mediated weak modulation of α4β2 and α6β2β3, whereas the NAMs exhibited essentially equipotent inhibition of α4β2, α6β2β3, α6β4β3, and α3β4 nAChRs, with analogue 9j [2-(2,4-dichlorophenoxy)-1,3-dimethyl-1-H-benzo[d]imidazole-3-ium] displaying high-nanomolar and low-micromolar IC50 values at the β2- and β4-containing receptor subtypes, respectively. We propose that the PAMs and NAMs act through overlapping sites in the nAChR, and these findings thus underline the heterogenous modes of modulation that can arise from a shared allosteric site in the receptor.
Collapse
Affiliation(s)
- Libin Zhou
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Vidan Dau
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| |
Collapse
|
25
|
Noonan JD, Beech RN. Two residues determine nicotinic acetylcholine receptor requirement for RIC-3. Protein Sci 2023; 32:e4718. [PMID: 37417463 PMCID: PMC10443321 DOI: 10.1002/pro.4718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 06/11/2023] [Accepted: 06/26/2023] [Indexed: 07/08/2023]
Abstract
Nicotinic acetylcholine receptors (N-AChRs) mediate fast synaptic signaling and are members of the pentameric ligand-gated ion channel (pLGIC) family. They rely on a network of accessory proteins in vivo for correct formation and transport to the cell surface. Resistance to cholinesterase 3 (RIC-3) is an endoplasmic reticulum protein that physically interacts with nascent pLGIC subunits and promotes their oligomerization. It is not known why some N-AChRs require RIC-3 in heterologous expression systems, whereas others do not. Previously we reported that the ACR-16 N-AChR from the parasitic nematode Dracunculus medinensis does not require RIC-3 in Xenopus laevis oocytes. This is unusual because all other nematode ACR-16, like the closely related Ascaris suum ACR-16, require RIC-3. Their high sequence similarity limits the number of amino acids that may be responsible, and the goal of this study was to identify them. A series of chimeras and point mutations between A. suum and D. medinensis ACR-16, followed by functional characterization with electrophysiology, identified two residues that account for a majority of the receptor requirement for RIC-3. ACR-16 with R/K159 in the cys-loop and I504 in the C-terminal tail did not require RIC-3 for functional expression. Mutating either of these to R/K159E or I504T, residues found in other nematode ACR-16, conferred a RIC-3 requirement. Our results agree with previous studies showing that these regions interact and are involved in receptor synthesis. Although it is currently unclear what precise mechanism they regulate, these residues may be critical during specific subunit folding and/or assembly cascades that RIC-3 may promote.
Collapse
Affiliation(s)
- Jennifer D. Noonan
- Institute of Parasitology, Macdonald Campus, McGill UniversityMontrealQuébecCanada
| | - Robin N. Beech
- Institute of Parasitology, Macdonald Campus, McGill UniversityMontrealQuébecCanada
| |
Collapse
|
26
|
Matera C, Papotto C, Dallanoce C, De Amici M. Advances in small molecule selective ligands for heteromeric nicotinic acetylcholine receptors. Pharmacol Res 2023; 194:106813. [PMID: 37302724 DOI: 10.1016/j.phrs.2023.106813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/26/2023] [Accepted: 06/02/2023] [Indexed: 06/13/2023]
Abstract
The study of nicotinic acetylcholine receptors (nAChRs) has significantly progressed in the last decade, due to a) the improved techniques available for structural studies; b) the identification of ligands interacting at orthosteric and allosteric recognition sites on the nAChR proteins, able to tune channel conformational states; c) the better functional characterization of receptor subtypes/subunits and their therapeutic potential; d) the availability of novel pharmacological agents able to activate or block nicotinic-mediated cholinergic responses with subtype or stoichiometry selectivity. The copious literature on nAChRs is related to the pharmacological profile of new, promising subtype selective derivatives as well as the encouraging preclinical and early clinical evaluation of known ligands. However, recently approved therapeutic derivatives are still missing, and examples of ligands discontinued in advanced CNS clinical trials include drug candidates acting at both neuronal homomeric and heteromeric receptors. In this review, we have selected heteromeric nAChRs as the target and comment on literature reports of the past five years dealing with the discovery of new small molecule ligands or the advanced pharmacological/preclinical investigation of more promising compounds. The results obtained with bifunctional nicotinic ligands and a light-activated ligand as well as the applications of promising radiopharmaceuticals for heteromeric subtypes are also discussed.
Collapse
Affiliation(s)
- Carlo Matera
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section "Pietro Pratesi", University of Milan, Via Luigi Mangiagalli 25, 20133 Milan, Italy
| | - Claudio Papotto
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section "Pietro Pratesi", University of Milan, Via Luigi Mangiagalli 25, 20133 Milan, Italy
| | - Clelia Dallanoce
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section "Pietro Pratesi", University of Milan, Via Luigi Mangiagalli 25, 20133 Milan, Italy
| | - Marco De Amici
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section "Pietro Pratesi", University of Milan, Via Luigi Mangiagalli 25, 20133 Milan, Italy.
| |
Collapse
|
27
|
Chen GL, Li J, Zhang J, Zeng B. To Be or Not to Be an Ion Channel: Cryo-EM Structures Have a Say. Cells 2023; 12:1870. [PMID: 37508534 PMCID: PMC10378246 DOI: 10.3390/cells12141870] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/13/2023] [Accepted: 07/16/2023] [Indexed: 07/30/2023] Open
Abstract
Ion channels are the second largest class of drug targets after G protein-coupled receptors. In addition to well-recognized ones like voltage-gated Na/K/Ca channels in the heart and neurons, novel ion channels are continuously discovered in both excitable and non-excitable cells and demonstrated to play important roles in many physiological processes and diseases such as developmental disorders, neurodegenerative diseases, and cancer. However, in the field of ion channel discovery, there are an unignorable number of published studies that are unsolid and misleading. Despite being the gold standard of a functional assay for ion channels, electrophysiological recordings are often accompanied by electrical noise, leak conductance, and background currents of the membrane system. These unwanted signals, if not treated properly, lead to the mischaracterization of proteins with seemingly unusual ion-conducting properties. In the recent ten years, the technical revolution of cryo-electron microscopy (cryo-EM) has greatly advanced our understanding of the structures and gating mechanisms of various ion channels and also raised concerns about the pore-forming ability of some previously identified channel proteins. In this review, we summarize cryo-EM findings on ion channels with molecular identities recognized or disputed in recent ten years and discuss current knowledge of proposed channel proteins awaiting cryo-EM analyses. We also present a classification of ion channels according to their architectures and evolutionary relationships and discuss the possibility and strategy of identifying more ion channels by analyzing structures of transmembrane proteins of unknown function. We propose that cross-validation by electrophysiological and structural analyses should be essentially required for determining molecular identities of novel ion channels.
Collapse
Affiliation(s)
- Gui-Lan Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| | - Jian Li
- College of Pharmaceutical Sciences, Gannan Medical University, Ganzhou 341000, China
| | - Jin Zhang
- School of Basic Medical Sciences, Nanchang University, Nanchang 330031, China
| | - Bo Zeng
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| |
Collapse
|
28
|
York JM, Borghese CM, George AA, Cannatella DC, Zakon HH. A potential cost of evolving epibatidine resistance in poison frogs. BMC Biol 2023; 21:144. [PMID: 37370119 DOI: 10.1186/s12915-023-01637-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 05/30/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND Some dendrobatid poison frogs sequester the toxin epibatidine as a defense against predators. We previously identified an amino acid substitution (S108C) at a highly conserved site in a nicotinic acetylcholine receptor β2 subunit of dendrobatid frogs that decreases sensitivity to epibatidine in the brain-expressing α4β2 receptor. Introduction of S108C to the orthologous high-sensitivity human receptor similarly decreased sensitivity to epibatidine but also decreased sensitivity to acetylcholine, a potential cost if this were to occur in dendrobatids. This decrease in the acetylcholine sensitivity manifested as a biphasic acetylcholine concentration-response curve consistent with the addition of low-sensitivity receptors. Surprisingly, the addition of the β2 S108C into the α4β2 receptor of the dendrobatid Epipedobates anthonyi did not change acetylcholine sensitivity, appearing cost-free. We proposed that toxin-bearing dendrobatids may have additional amino acid substitutions protecting their receptors from alterations in acetylcholine sensitivity. To test this, in the current study, we compared the dendrobatid receptor to its homologs from two non-dendrobatid frogs. RESULTS The introduction of S108C into the α4β2 receptors of two non-dendrobatid frogs also does not affect acetylcholine sensitivity suggesting no additional dendrobatid-specific substitutions. However, S108C decreased the magnitude of neurotransmitter-induced currents in Epipedobates and the non-dendrobatid frogs. We confirmed that decreased current resulted from fewer receptors in the plasma membrane in Epipedobates using radiolabeled antibodies against the receptors. To test whether S108C alteration of acetylcholine sensitivity in the human receptor was due to (1) adding low-sensitivity binding sites by changing stoichiometry or (2) converting existing high- to low-sensitivity binding sites with no stoichiometric alteration, we made concatenated α4β2 receptors in stoichiometry with only high-sensitivity sites. S108C substitutions decreased maximal current and number of immunolabeled receptors but no longer altered acetylcholine sensitivity. CONCLUSIONS The most parsimonious explanation of our current and previous work is that the S108C substitution renders the β2 subunit less efficient in assembling/trafficking, thereby decreasing the number of receptors in the plasma membrane. Thus, while β2 S108C protects dendrobatids against sequestered epibatidine, it incurs a potential physiological cost of disrupted α4β2 receptor function.
Collapse
Affiliation(s)
- Julia M York
- Department of Neuroscience, The University of Texas, Austin, TX, USA
- Department of Integrative Biology, and Biodiversity Center, The University of Texas, Austin, TX, USA
| | | | - Andrew A George
- Department of Neurobiology, The Barrow Neurological Institute, Phoenix, AZ, USA
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - David C Cannatella
- Department of Integrative Biology, and Biodiversity Center, The University of Texas, Austin, TX, USA
| | - Harold H Zakon
- Department of Neuroscience, The University of Texas, Austin, TX, USA.
- Department of Integrative Biology, and Biodiversity Center, The University of Texas, Austin, TX, USA.
| |
Collapse
|
29
|
Strikwerda JR, Natarajan K, Sine SM. Impact on AChR open channel noise by pore-peripheral salt bridge depends on voltage and divalent cations. Biophys J 2023; 122:2430-2444. [PMID: 37113056 PMCID: PMC10322898 DOI: 10.1016/j.bpj.2023.04.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/16/2023] [Accepted: 04/24/2023] [Indexed: 04/29/2023] Open
Abstract
Mechanisms behind the fluctuations in the ionic current through single acetylcholine receptor (AChR) channels have remained elusive. In a recent study of muscle AChR we showed that mutation of a conserved intramembrane salt bridge in the β- and δ-subunits markedly increased fluctuations in the open channel current that extended from low to high frequency. Here, we show that extracellular divalent cations reduce the high-frequency fluctuations and increase the low-frequency fluctuations. The low-frequency fluctuations are shown to arise from steps between two current levels, with the ratio of the time at each level changing e-fold for a 70 mV increase in membrane potential, indicating modulation by a charged element within the membrane field. Increasing the charge on the ion selectivity filter biases the ratio of current levels equivalent to a 50 mV increase in membrane potential but does not alter the voltage dependence of the ratio. The magnitudes of the voltage dependence and voltage bias allow estimates of the distance between the ion selectivity filter and the voltage-sensing element. Studies with either calcium or magnesium show that the two divalent cations synergize to increase the low-frequency fluctuations, whereas they act independently to decrease the high-frequency fluctuations, indicating multiple divalent cation binding sites. Molecular dynamics simulations applied to the structure of the Torpedo AChR reveal that mutation of the salt bridge alters the equilibrium positions and dynamics of residues local to the site of the mutation and within the adjacent ion selectivity filter in a calcium-dependent manner. Thus, disruption of a conserved intramembrane salt bridge in the muscle AChR induces fluctuations in open channel current that are sensitive to divalent cation binding at multiple sites and modulated by a charged element within the membrane field.
Collapse
Affiliation(s)
- John R Strikwerda
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Rochester, Minnesota
| | - Kathiresan Natarajan
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Rochester, Minnesota
| | - Steven M Sine
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Rochester, Minnesota; Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, Minnesota; Department of Neurology, Mayo Clinic College of Medicine and Science, Rochester, Minnesota.
| |
Collapse
|
30
|
Li Q, Nemecz Á, Aymé G, Dejean de la Bâtie G, Prevost MS, Pons S, Barilone N, Baachaoui R, Maskos U, Lafaye P, Corringer PJ. Generation of nanobodies acting as silent and positive allosteric modulators of the α7 nicotinic acetylcholine receptor. Cell Mol Life Sci 2023; 80:164. [PMID: 37231269 DOI: 10.1007/s00018-023-04779-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/28/2023] [Accepted: 04/07/2023] [Indexed: 05/27/2023]
Abstract
The α7 nicotinic acetylcholine receptor (nAChR), a potential drug target for treating cognitive disorders, mediates communication between neuronal and non-neuronal cells. Although many competitive antagonists, agonists, and partial-agonists have been found and synthesized, they have not led to effective therapeutic treatments. In this context, small molecules acting as positive allosteric modulators binding outside the orthosteric, acetylcholine, site have attracted considerable interest. Two single-domain antibody fragments, C4 and E3, against the extracellular domain of the human α7-nAChR were generated through alpaca immunization with cells expressing a human α7-nAChR/mouse 5-HT3A chimera, and are herein described. They bind to the α7-nAChR but not to the other major nAChR subtypes, α4β2 and α3β4. E3 acts as a slowly associating positive allosteric modulator, strongly potentiating the acetylcholine-elicited currents, while not precluding the desensitization of the receptor. An E3-E3 bivalent construct shows similar potentiating properties but displays very slow dissociation kinetics conferring quasi-irreversible properties. Whereas, C4 does not alter the receptor function, but fully inhibits the E3-evoked potentiation, showing it is a silent allosteric modulator competing with E3 binding. Both nanobodies do not compete with α-bungarotoxin, localizing at an allosteric extracellular binding site away from the orthosteric site. The functional differences of each nanobody, as well as the alteration of functional properties through nanobody modifications indicate the importance of this extracellular site. The nanobodies will be useful for pharmacological and structural investigations; moreover, they, along with the extracellular site, have a direct potential for clinical applications.
Collapse
Affiliation(s)
- Qimeng Li
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France
- Lanzhou Institute of Biological Product Co., Lanzhou, China
- Sorbonne Université, Collège Doctoral, Paris, France
| | - Ákos Nemecz
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France.
| | - Gabriel Aymé
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France.
| | | | - Marie S Prevost
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
| | - Stéphanie Pons
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Integrative Neurobiology of Cholinergic Systems Unit, Paris, France
| | - Nathalie Barilone
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
| | - Rayen Baachaoui
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France
| | - Uwe Maskos
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Integrative Neurobiology of Cholinergic Systems Unit, Paris, France
| | - Pierre Lafaye
- Institut Pasteur, Université Paris Cité, CNRS UMR 3528, Antibody Engineering Platform, Paris, France
| | - Pierre-Jean Corringer
- Institut Pasteur, Université Paris Cité, CNRS UMR 3571, Channel-Receptors Unit, Paris, France.
| |
Collapse
|
31
|
Quesada O, González-Nieves JE, Colón J, Maldonado-Hernández R, González-Freire C, Acevedo-Cintrón J, Rosado-Millán ID, Lasalde-Dominicci JA. Assessment of Purity, Functionality, Stability, and Lipid Composition of Cyclofos-nAChR-Detergent Complexes from Torpedo californica Using Lipid Matrix and Macroscopic Electrophysiology. J Membr Biol 2023; 256:271-285. [PMID: 37140614 PMCID: PMC10157581 DOI: 10.1007/s00232-023-00285-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 03/27/2023] [Indexed: 05/05/2023]
Abstract
The main objective of the present study was to find detergents that can maintain the functionality and stability of the Torpedo californica nicotinic acetylcholine receptor (Tc-nAChR). We examined the functionality, stability, and purity analysis of affinity-purified Tc-nAChR solubilized in detergents from the Cyclofos (CF) family [cyclofoscholine 4 (CF-4), cyclofoscholine 6 (CF-6), and cyclofloscholine 7 (CF-7)]. The functionality of the CF-Tc-nAChR-detergent complex (DC) was evaluated using the Two Electrode Voltage Clamp (TEVC) method. To assess stability, we used the florescence recovery after photobleaching (FRAP) in Lipidic Cubic Phase (LCP) methodology. We also performed a lipidomic analysis using Ultra-Performance Liquid Chromatography (UPLC) coupled to electrospray ionization mass spectrometry (ESI-MS/MS) to evaluate the lipid composition of the CF-Tc-nAChR-DCs. The CF-4-Tc-nAChR-DC displayed a robust macroscopic current (- 200 ± 60 nA); however, the CF-6-Tc-nAChR-DC and CF-7-Tc-nAChR-DC displayed significant reductions in the macroscopic currents. The CF-6-Tc-nAChR and CF-4-Tc-nAChR displayed higher fractional florescence recovery. Addition of cholesterol produced a mild enhancement of the mobile fraction on the CF-6-Tc-nAChR. The lipidomic analysis revealed that the CF-7-Tc-nAChR-DC displayed substantial delipidation, consistent with the lack of stability and functional response of this complex. Although the CF-6-nAChR-DC complex retained the largest amount of lipids, it showed a loss of six lipid species [SM(d16:1/18:0); PC(18:2/14:1); PC(14:0/18:1); PC(16:0/18:1); PC(20:5/20:4), and PC(20:4/20:5)] that are present in the CF-4-nAChR-DC. Overall, the CF-4-nAChR displayed robust functionality, significant stability, and the best purity among the three CF detergents; therefore, CF-4 is a suitable candidate to prepare Tc-nAChR crystals for structural studies.
Collapse
Affiliation(s)
- Orestes Quesada
- Department of Physical Sciences, University of Puerto Rico, Río Piedras Campus, San Juan, PR, USA.
- Department of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan, PR, USA.
- Molecular Science Center, University of Puerto Rico, San Juan, PR, USA.
| | | | - José Colón
- Department of Pharmaceutical Sciences, Medical Sciences Campus, University of Puerto Rico, San Juan, PR, USA
- Molecular Science Center, University of Puerto Rico, San Juan, PR, USA
| | - Rafael Maldonado-Hernández
- Department of Biology, University of Puerto Rico, Ponce Campus, Ponce, PR, USA
- Molecular Science Center, University of Puerto Rico, San Juan, PR, USA
| | - Carol González-Freire
- Department of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan, PR, USA
| | - Jesús Acevedo-Cintrón
- Department of Biology, University of Puerto Rico, Río Piedras Campus, San Juan, PR, USA
| | - Irvin D Rosado-Millán
- Department of Biology, University of Puerto Rico, Río Piedras Campus, San Juan, PR, USA
| | - José A Lasalde-Dominicci
- Department of Biology, University of Puerto Rico, Río Piedras Campus, San Juan, PR, USA.
- Department of Pharmaceutical Sciences, Medical Sciences Campus, University of Puerto Rico, San Juan, PR, USA.
- Molecular Science Center, University of Puerto Rico, San Juan, PR, USA.
- Institute of Neurobiology, University of Puerto Rico, Medical Science Campus, San Juan, PR, USA.
| |
Collapse
|
32
|
Sanders VR, Millar NS. Potentiation and allosteric agonist activation of α7 nicotinic acetylcholine receptors: binding sites and hypotheses. Pharmacol Res 2023; 191:106759. [PMID: 37023990 DOI: 10.1016/j.phrs.2023.106759] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/27/2023] [Accepted: 03/30/2023] [Indexed: 04/07/2023]
Abstract
Considerable progress has been made in recent years towards the identification and characterisation of novel subtype-selective modulators of nicotinic acetylcholine receptors (nAChRs). In particular, this has focussed on modulators of α7 nAChRs, a nAChR subtype that has been identified as a target for drug discovery in connection with a range of potential therapeutic applications. This review focusses upon α7-selective modulators that bind to receptor sites other than the extracellular 'orthosteric' agonist binding site for the endogenous agonist acetylcholine (ACh). Such compounds include those that are able to potentiate responses evoked by orthosteric agonists such as ACh (positive allosteric modulators; PAMs) and those that are able to activate α7 nAChRs by direct allosteric activation in the absence of an orthosteric agonist (allosteric agonists or 'ago-PAMs'). There has been considerable debate about the mechanism of action of α7-selective PAMs and allosteric agonists, much of which has centred around identifying the location of their binding sites on α7 nAChRs. Based on a variety of experimental evidence, including recent structural data, there is now clear evidence indicating that at least some α7-selective PAMs bind to an inter-subunit site located in the transmembrane domain. In contrast, there are differing hypotheses about the site or sites at which allosteric agonists bind to α7 nAChRs. It will be argued that the available evidence supports the conclusion that direct allosteric activation by allosteric agonists/ago-PAMs occurs via the same inter-subunit transmembrane site that has been identified for several α7-selective PAMs.
Collapse
Affiliation(s)
- Victoria R Sanders
- Division of Biosciences, University College London, London WC1E 6BT, United Kingdom
| | - Neil S Millar
- Division of Biosciences, University College London, London WC1E 6BT, United Kingdom.
| |
Collapse
|
33
|
Papke RL, Quadri M, Gulsevin A. Silent agonists for α7 nicotinic acetylcholine receptors. Pharmacol Res 2023; 190:106736. [PMID: 36940890 DOI: 10.1016/j.phrs.2023.106736] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 03/07/2023] [Accepted: 03/14/2023] [Indexed: 03/23/2023]
Abstract
We discuss models for the activation and desensitization of α7 nicotinic acetylcholine receptors (nAChRs) and the effects of efficacious type II positive allosteric modulators (PAMs) that destabilize α7 desensitized states. Type II PAMs such as PNU-120596 can be used to distinguish inactive compounds from silent agonists, compounds that produce little or no channel activation but stabilize the non-conducting conformations associated with desensitization. We discuss the effects of α7 nAChRs in cells of the immune system and their roles in modulating inflammation and pain through what has come to be known as the cholinergic anti-inflammatory system (CAS). Cells controlling CAS do not generate ion channel currents but rather respond to α7 drugs by modulating intracellular signaling pathways analogous to the effects of metabotropic receptors. Metabotropic signaling by α7 receptors appears to be mediated by receptors in nonconducting conformations and can be accomplished by silent agonists. We discuss electrophysiological structure-activity relationships for α7 silent agonists and their use in cell-based and in vivo assays for CAS regulation. We discuss the strongly desensitizing partial agonist GTS-21 and its effectiveness in modulation of CAS. We also review the properties of the silent agonist NS6740, which is remarkably effective at maintaining α7 receptors in PAM-sensitive desensitized states. Most silent agonists bind to sites overlapping those for orthosteric agonists, but some appear to bind to allosteric sites. Finally, we discuss α9⁎ nAChRs and their potential role in CAS, and ligands that will be useful in defining and distinguishing the specific roles of α7 and α9 in CAS.
Collapse
Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267 Gainesville, FL 32610 USA (RLP); Olon S.p.A., Strada Rivoltana, Km 6/7 - 20053 Rodano (MI) - ITALY (MQ); Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA, 37212 (AG).
| | - Marta Quadri
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267 Gainesville, FL 32610 USA (RLP); Olon S.p.A., Strada Rivoltana, Km 6/7 - 20053 Rodano (MI) - ITALY (MQ); Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA, 37212 (AG)
| | - Alican Gulsevin
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267 Gainesville, FL 32610 USA (RLP); Olon S.p.A., Strada Rivoltana, Km 6/7 - 20053 Rodano (MI) - ITALY (MQ); Department of Chemistry, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA, 37212 (AG)
| |
Collapse
|
34
|
Barrantes FJ. Structure and function meet at the nicotinic acetylcholine receptor-lipid interface. Pharmacol Res 2023; 190:106729. [PMID: 36931540 DOI: 10.1016/j.phrs.2023.106729] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023]
Abstract
The nicotinic acetylcholine receptor (nAChR) is a transmembrane protein that mediates fast intercellular communication in response to the endogenous neurotransmitter acetylcholine. It is the best characterized and archetypal molecule in the superfamily of pentameric ligand-gated ion channels (pLGICs). As a typical transmembrane macromolecule, it interacts extensively with its vicinal lipid microenvironment. Experimental evidence provides a wealth of information on receptor-lipid crosstalk: the nAChR exerts influence on its immediate membrane environment and conversely, the lipid moiety modulates ligand binding, affinity state transitions and gating of ion translocation functions of the receptor protein. Recent cryogenic electron microscopy (cryo-EM) studies have unveiled the occurrence of sites for phospholipids and cholesterol on the lipid-exposed regions of neuronal and electroplax nAChRs, confirming early spectroscopic and affinity labeling studies demonstrating the close contact of lipid molecules with the receptor transmembrane segments. This new data provides structural support to the postulated "lipid sensor" ability displayed by the outer ring of M4 transmembrane domains and their modulatory role on nAChR function, as we postulated a decade ago. Borrowing from the best characterized nAChR, the electroplax (muscle-type) receptor, and exploiting new structural information on the neuronal nAChR, it is now possible to achieve an improved depiction of these sites. In combination with site-directed mutagenesis, single-channel electrophysiology, and molecular dynamics studies, the new structural information delivers a more comprehensive portrayal of these lipid-sensitive loci, providing mechanistic explanations for their ability to modulate nAChR properties and raising the possibility of targetting them in disease.
Collapse
Affiliation(s)
- Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Biomedical Research Institute, Faculty of Medical Sciences, Pontifical Catholic University of Argentina (UCA) - Argentine Scientific & Technol. Research Council (CONICET), Av. Alicia Moreau de Justo 1600, C1107AAZ Buenos Aires, Argentina.
| |
Collapse
|
35
|
Elgoyhen AB. The α9α10 acetylcholine receptor: a non-neuronal nicotinic receptor. Pharmacol Res 2023; 190:106735. [PMID: 36931539 DOI: 10.1016/j.phrs.2023.106735] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/06/2023] [Accepted: 03/14/2023] [Indexed: 03/17/2023]
Abstract
Within the superfamily of pentameric ligand-gated ion channels, cholinergic nicotinic receptors (nAChRs) were classically identified to mediate synaptic transmission in the nervous system and the neuromuscular junction. The α9 and α10 nAChR subunits were the last ones to be identified. Surprisingly, they do not fall into the dichotomic neuronal/muscle classification of nAChRs. They assemble into heteropentamers with a well-established function as canonical ion channels in inner ear hair cells, where they mediate central nervous system control of auditory and vestibular sensory processing. The present review includes expression, pharmacological, structure-function, molecular evolution and pathophysiological studies, that define receptors composed from α9 and α10 subunits as distant and distinct members within the nAChR family. Thus, although α9 and α10 were initially included within the neuronal subdivision of nAChR subunits, they form a distinct clade within the phylogeny of nAChRs. Following the classification of nAChR subunits based on their main synaptic site of action, α9 and α10 should receive a name in their own right.
Collapse
Affiliation(s)
- Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Vuelta de Obligado 2490, Buenos Aires 1428, Argentina.
| |
Collapse
|
36
|
York JM, Borghese CM, George AA, Cannatella DC, Zakon HH. A potential cost of evolving epibatidine resistance in poison frogs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.04.522789. [PMID: 36711899 PMCID: PMC9882002 DOI: 10.1101/2023.01.04.522789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Background Some poison arrow frogs sequester the toxin epibatidine as a defense against predators. We previously identified a single amino acid substitution (S108C) at a highly conserved site in a neuronal nicotinic acetylcholine receptor (nAChR) ß2 subunit that prevents epibatidine from binding to this receptor. When placed in a homologous mammalian nAChR this substitution minimized epibatidine binding but also perturbed acetylcholine binding, a clear cost. However, in the nAChRs of poison arrow frogs, this substitution appeared to have no detrimental effect on acetylcholine binding and, thus, appeared cost-free. Results The introduction of S108C into the α4β2 nAChRs of non-dendrobatid frogs also does not affect ACh sensitivity, when these receptors are expressed in Xenopus laevis oocytes. However, α4β2 nAChRs with C108 had a decreased magnitude of neurotransmitter-induced currents in all species tested ( Epipedobates anthonyi , non-dendrobatid frogs, as well as human), compared with α4β2 nAChRs with the conserved S108. Immunolabeling of frog or human α4β2 nAChRs in the plasma membrane using radiolabeled antibody against the β2 nAChR subunit shows that C108 significantly decreased the number of cell-surface α4β2 nAChRs, compared with S108. Conclusions While S108C protects these species against sequestered epibatidine, it incurs a potential physiological cost of disrupted α4β2 nAChR function. These results may explain the high conservation of a serine at this site in vertebrates, as well as provide an example of a tradeoff between beneficial and deleterious effects of an evolutionary change. They also provide important clues for future work on assembly and trafficking of this important neurotransmitter receptor.
Collapse
|
37
|
Zhang HJ, Zammit M, Kao CM, Govind AP, Mitchell S, Holderman N, Bhuiyan M, Freifelder R, Kucharski A, Zhuang X, Mukherjee J, Chen CT, Green WN. Trapping of Nicotinic Acetylcholine Receptor Ligands Assayed by In Vitro Cellular Studies and In Vivo PET Imaging. J Neurosci 2023; 43:2-13. [PMID: 36028313 PMCID: PMC9838697 DOI: 10.1523/jneurosci.2484-21.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 08/07/2022] [Accepted: 08/13/2022] [Indexed: 01/19/2023] Open
Abstract
A question relevant to nicotine addiction is how nicotine and other nicotinic receptor membrane-permeant ligands, such as the anti-smoking drug varenicline (Chantix), distribute in brain. Ligands, like varenicline, with high pKa and high affinity for α4β2-type nicotinic receptors (α4β2Rs) are trapped in intracellular acidic vesicles containing α4β2Rs in vitro Nicotine, with lower pKa and α4β2R affinity, is not trapped. Here, we extend our results by imaging nicotinic PET ligands in vivo in male and female mouse brain and identifying the trapping brain organelle in vitro as Golgi satellites (GSats). Two PET 18F-labeled imaging ligands were chosen: [18F]2-FA85380 (2-FA) with varenicline-like pKa and affinity and [18F]Nifene with nicotine-like pKa and affinity. [18F]2-FA PET-imaging kinetics were very slow consistent with 2-FA trapping in α4β2R-containing GSats. In contrast, [18F]Nifene kinetics were rapid, consistent with its binding to α4β2Rs but no trapping. Specific [18F]2-FA and [18F]Nifene signals were eliminated in β2 subunit knock-out (KO) mice or by acute nicotine (AN) injections demonstrating binding to sites on β2-containing receptors. Chloroquine (CQ), which dissipates GSat pH gradients, reduced [18F]2-FA distributions while having little effect on [18F]Nifene distributions in vivo consistent with only [18F]2-FA trapping in GSats. These results are further supported by in vitro findings where dissipation of GSat pH gradients blocks 2-FA trapping in GSats without affecting Nifene. By combining in vitro and in vivo imaging, we mapped both the brain-wide and subcellular distributions of weak-base nicotinic receptor ligands. We conclude that ligands, such as varenicline, are trapped in neurons in α4β2R-containing GSats, which results in very slow release long after nicotine is gone after smoking.SIGNIFICANCE STATEMENT Mechanisms of nicotine addiction remain poorly understood. An earlier study using in vitro methods found that the anti-smoking nicotinic ligand, varenicline (Chantix) was trapped in α4β2R-containing acidic vesicles. Using a fluorescent-labeled high-affinity nicotinic ligand, this study provided evidence that these intracellular acidic vesicles were α4β2R-containing Golgi satellites (GSats). In vivo PET imaging with F-18-labeled nicotinic ligands provided additional evidence that differences in PET ligand trapping in acidic vesicles were the cause of differences in PET ligand kinetics and subcellular distributions. These findings combining in vitro and in vivo imaging revealed new mechanistic insights into the kinetics of weak base PET imaging ligands and the subcellular mechanisms underlying nicotine addiction.
Collapse
Affiliation(s)
- Hannah J Zhang
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - Matthew Zammit
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - Chien-Min Kao
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - Anitha P Govind
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
| | - Samuel Mitchell
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | | | - Mohammed Bhuiyan
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | | | - Anna Kucharski
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - Xiaoxi Zhuang
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
| | - Jogeshwar Mukherjee
- Departments of Preclinical Imaging and Radiological Sciences, University of California, Irvine, California 92697
| | - Chin-Tu Chen
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - William N Green
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543
| |
Collapse
|
38
|
Yao H, Cai H, Li D. Fluorescence-Detection Size-Exclusion Chromatography-Based Thermostability Assay for Membrane Proteins. Methods Mol Biol 2023; 2564:299-315. [PMID: 36107350 DOI: 10.1007/978-1-0716-2667-2_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Green fluorescent proteins (GFPs) have lightened up almost every aspect of biological research including protein sciences. In the field of membrane protein structural biology, GFPs have been used widely to monitor membrane protein localization, expression level, the purification process and yield, and the stability inside the cells and in the test tube. Of particular interest is the fluorescence-detector size-exclusion chromatography-based thermostability assay (FSEC-TS). By simple heating and FSEC, the generally applicable method allows rapid assessment of the thermostability of GFP-fused membrane proteins without purification. Here we describe the experimental details and some typical results for the FSEC-TS method.
Collapse
Affiliation(s)
| | | | - Dianfan Li
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.
| |
Collapse
|
39
|
Biophysical characterization of calcium-binding and modulatory-domain dynamics in a pentameric ligand-gated ion channel. Proc Natl Acad Sci U S A 2022; 119:e2210669119. [PMID: 36480474 PMCID: PMC9897478 DOI: 10.1073/pnas.2210669119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) perform electrochemical signal transduction in organisms ranging from bacteria to humans. Among the prokaryotic pLGICs, there is architectural diversity involving N-terminal domains (NTDs) not found in eukaryotic relatives, exemplified by the calcium-sensitive channel (DeCLIC) from a Desulfofustis deltaproteobacterium, which has an NTD in addition to the canonical pLGIC structure. Here, we have characterized the structure and dynamics of DeCLIC through cryoelectron microscopy (cryo-EM), small-angle neutron scattering (SANS), and molecular dynamics (MD) simulations. In the presence and absence of calcium, cryo-EM yielded structures with alternative conformations of the calcium-binding site. SANS profiles further revealed conformational diversity at room temperature beyond that observed in static structures, shown through MD to be largely attributable to rigid-body motions of the NTD relative to the protein core, with expanded and asymmetric conformations improving the fit of the SANS data. This work reveals the range of motion available to the DeCLIC NTD and calcium-binding site, expanding the conformational landscape of the pLGIC family. Further, these findings demonstrate the power of combining low-resolution scattering, high-resolution structural, and MD simulation data to elucidate interfacial interactions that are highly conserved in the pLGIC family.
Collapse
|
40
|
Batista VS, Gonçalves AM, Nascimento-Júnior NM. Pharmacophore Mapping Combined with dbCICA Reveal New Structural Features for the Development of Novel Ligands Targeting α4β2 and α7 Nicotinic Acetylcholine Receptors. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238236. [PMID: 36500328 PMCID: PMC9735964 DOI: 10.3390/molecules27238236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/04/2022] [Accepted: 11/10/2022] [Indexed: 11/29/2022]
Abstract
The neuronal nicotinic acetylcholine receptors (nAChRs) belong to the ligand-gated ion channel (GLIC) group, presenting a crucial role in several biological processes and neuronal disorders. The α4β2 and α7 nAChRs are the most abundant in the central nervous system (CNS), being involved in challenging diseases such as epilepsy, Alzheimer's disease, schizophrenia, and anxiety disorder, as well as alcohol and nicotine dependencies. In addition, in silico-based strategies may contribute to revealing new insights into drug design and virtual screening to find new drug candidates to treat CNS disorders. In this context, the pharmacophore maps were constructed and validated for the orthosteric sites of α4β2 and α7 nAChRs, through a docking-based Comparative Intermolecular Contacts Analysis (dbCICA). In this sense, bioactive ligands were retrieved from the literature for each receptor. A molecular docking protocol was developed for all ligands in both receptors by using GOLD software, considering GoldScore, ChemScore, ASP, and ChemPLP scoring functions. Output GOLD results were post-processed through dbCICA to identify critical contacts involved in protein-ligand interactions. Moreover, Crossminer software was used to construct a pharmacophoric map based on the most well-behaved ligands and negative contacts from the dbCICA model for each receptor. Both pharmacophore maps were validated by using a ROC curve. The results revealed important features for the ligands, such as the presence of hydrophobic regions, a planar ring, and hydrogen bond donor and acceptor atoms for α4β2. Parallelly, a non-planar ring region was identified for α7. These results can enable fragment-based drug design (FBDD) strategies, such as fragment growing, linking, and merging, allowing an increase in the activity of known fragments. Thus, our results can contribute to a further understanding of structural subunits presenting the potential for key ligand-receptor interactions, favoring the search in molecular databases and the design of novel ligands.
Collapse
Affiliation(s)
- Victor S. Batista
- Laboratory of Medicinal Chemistry, Organic Synthesis and Molecular Modeling (LaQMedSOMM), Department of Biochemistry and Organic Chemistry, Institute of Chemistry, São Paulo State University (Unesp), Rua Professor Francisco Degni, 55, Jardim Quitandinha, Araraquara 14800-060, SP, Brazil
| | - Adriano Marques Gonçalves
- Laboratory of Medicinal Chemistry, Organic Synthesis and Molecular Modeling (LaQMedSOMM), Department of Biochemistry and Organic Chemistry, Institute of Chemistry, São Paulo State University (Unesp), Rua Professor Francisco Degni, 55, Jardim Quitandinha, Araraquara 14800-060, SP, Brazil
- Department of Biological and Health Sciences, University of Araraquara (Uniara), Rua Carlos Gomes, 1217, Centro, Araraquara 14801-340, SP, Brazil
| | - Nailton M. Nascimento-Júnior
- Laboratory of Medicinal Chemistry, Organic Synthesis and Molecular Modeling (LaQMedSOMM), Department of Biochemistry and Organic Chemistry, Institute of Chemistry, São Paulo State University (Unesp), Rua Professor Francisco Degni, 55, Jardim Quitandinha, Araraquara 14800-060, SP, Brazil
- Correspondence:
| |
Collapse
|
41
|
Kaiser J, Gertzen CG, Bernauer T, Höfner G, Niessen KV, Seeger T, Paintner FF, Wanner KT, Worek F, Thiermann H, Gohlke H. A novel binding site in the nicotinic acetylcholine receptor for MB327 can explain its allosteric modulation relevant for organophosphorus-poisoning treatment. Toxicol Lett 2022; 373:160-171. [DOI: 10.1016/j.toxlet.2022.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 11/25/2022] [Indexed: 11/27/2022]
|
42
|
Mazzaferro S, Msekela DJ, Cooper EC, Maheshwari A, Sine SM. Genetic Variant in Nicotinic Receptor α4-Subunit Causes Sleep-Related Hyperkinetic Epilepsy via Increased Channel Opening. Int J Mol Sci 2022; 23:12124. [PMID: 36292983 PMCID: PMC9602795 DOI: 10.3390/ijms232012124] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 09/30/2022] [Accepted: 10/07/2022] [Indexed: 02/03/2023] Open
Abstract
We describe genetic and molecular-level functional alterations in the α4β2 neuronal nicotinic acetylcholine receptor (nAChR) from a patient with sleep-related hyperkinetic epilepsy and a family history of epilepsy. Genetic sequencing revealed a heterozygous variant c.851C>G in the CHRNA4 gene encoding the α4 subunit, resulting in the missense mutation p.Ser284Trp. Patch clamp recordings from genetically engineered nAChRs incorporating the α4-Ser284Trp subunit revealed aberrant channel openings in the absence of agonist and markedly prolonged openings in its presence. Measurements of single channel current amplitude distinguished two pentameric stoichiometries of the variant nAChR containing either two or three copies of the α4-Ser284Trp subunit, each exhibiting aberrant spontaneous and prolonged agonist-elicited channel openings. The α4-Ser284 residue is highly conserved and located within the M2 transmembrane α-helix that lines the ion channel. When mapped onto the receptor’s three-dimensional structure, the larger Trp substitution sterically clashes with the M2 α-helix from the neighboring subunit, promoting expansion of the pore and stabilizing the open relative to the closed conformation of the channel. Together, the clinical, genetic, functional, and structural observations demonstrate that α4-Ser284Trp enhances channel opening, predicting increased membrane excitability and a pathogenic seizure phenotype.
Collapse
Affiliation(s)
- Simone Mazzaferro
- Departments of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
| | - Deborah J. Msekela
- Departments of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
| | - Edward C. Cooper
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Atul Maheshwari
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Steven M. Sine
- Departments of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
- Departments of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
- Departments of Neurology, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
| |
Collapse
|
43
|
Saponaro A, Lolicato M. Editorial: The key role of lipids in the regulation of ion channels. Front Physiol 2022; 13:1000082. [PMID: 36160863 PMCID: PMC9490410 DOI: 10.3389/fphys.2022.1000082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 08/12/2022] [Indexed: 11/16/2022] Open
Affiliation(s)
- Andrea Saponaro
- Department of Biosciences, University of Milano, Milano, Italy
- *Correspondence: Andrea Saponaro,
| | - Marco Lolicato
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| |
Collapse
|
44
|
Parker HP, Dawson A, Jones MJ, Yan R, Ouyang J, Hong R, Hunter WN. Delineating the activity of the potent nicotinic acetylcholine receptor agonists (+)-anatoxin-a and (−)-hosieine-A. Acta Crystallogr F Struct Biol Commun 2022; 78:313-323. [PMID: 36048081 PMCID: PMC9435674 DOI: 10.1107/s2053230x22007762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/01/2022] [Indexed: 11/10/2022] Open
Abstract
The affinity and thermodynamic parameters for the interactions of two naturally occurring neurotoxins, (+)-anatoxin-a and (−)-hosieine-A, with acetylcholine-binding protein were investigated using a fluorescence-quenching assay and isothermal titration calorimetry. The crystal structures of their complexes with acetylcholine-binding protein from Aplysia californica (AcAChBP) were determined and reveal details of molecular recognition in the orthosteric binding site. Comparisons treating AcAChBP as a surrogate for human α4β2 and α7 nicotinic acetylcholine receptors (nAChRs) suggest that the molecular features involved in ligand recognition and affinity for the protein targets are conserved. The ligands exploit interactions with similar residues as the archetypal nAChR agonist nicotine, but with greater affinity. (−)-Hosieine-A in particular has a high affinity for AcAChBP driven by a favorable entropic contribution to binding. The ligand affinities help to rationalize the potent biological activity of these alkaloids. The structural data, together with comparisons with related molecules, suggest that there may be opportunities to extend the hosieine-A scaffold to incorporate new interactions with the complementary side of the orthosteric binding site. Such a strategy may guide the design of new entities to target human α4β2 nAChR that may have therapeutic benefit.
Collapse
|
45
|
Santis GD, Takeda N, Hirata K, Tsuruta K, Ishiuchi SI, Xantheas SS, Fujii M. Structure of Gas Phase Monohydrated Nicotine: Implications for Nicotine's Native Structure in the Acetylcholine Binding Protein. J Am Chem Soc 2022; 144:16698-16702. [PMID: 36043852 DOI: 10.1021/jacs.2c04064] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report a joint experimental-theoretical study of the never reported before structure and infrared spectra of gas phase monohydrated nicotine (NIC) and nornicotine (NOR) and use them to assign their protonation sites. NIC's biological activity is strongly affected by its protonation site, namely, the pyrrolidine (Pyrro-NICH+, anticipated active form) and pyridine (Pyri-NICH+) forms; however, these have yet to be directly experimentally determined in either the nicotinic acetylcholine receptor (nAChR, no water present) or the acetylcholine-binding protein (AChBP, a single water molecule is present) but can only be inferred to be Pyrro-NICH+ from the intermolecular distance to the neighboring residues (i.e., tryptophan). Our temperature-controlled double ion trap infrared spectroscopic experiments assisted by the collisional stripping method and high-level theoretical calculations yield the protonation ratio of Pyri:Pyrro = 8:2 at 240 K for the gas phase NICH+···(H2O) complex, which resembles the molecular cluster present in the AChBP. Therefore, a single water molecule in the gas phase enhances this ratio in NICH+ relative to the 3:2 for the nonhydrated gas phase NICH+ in a trend that contrasts with the almost exclusive presence of Pyrro-NICH+ in aqueous solution. In contrast, the Pyri-NORH+ protomer is exclusively observed, a fact that may correlate with its weaker biological activity.
Collapse
Affiliation(s)
- Garrett D Santis
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Naoya Takeda
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Kazuya Tsuruta
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 4259 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,IIR Program for World Research (IPWR), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Sotiris S Xantheas
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington 99352, United States
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan.,Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovation Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| |
Collapse
|
46
|
Knox HJ, Rego Campello H, Lester HA, Gallagher T, Dougherty DA. Characterization of Binding Site Interactions and Selectivity Principles in the α3β4 Nicotinic Acetylcholine Receptor. J Am Chem Soc 2022; 144:16101-16117. [PMID: 36006801 DOI: 10.1021/jacs.2c06495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) play an important role in neurotransmission and are also involved in addiction and several disease states. There is significant interest in therapeutic targeting of nAChRs; however, achieving selectivity for one subtype over others has been a longstanding challenge, given the close structural similarities across the family. Here, we characterize binding interactions in the α3β4 nAChR subtype via structure-function studies involving noncanonical amino acid mutagenesis and two-electrode voltage clamp electrophysiology. We establish comprehensive binding models for both the endogenous neurotransmitter ACh and the smoking cessation drug cytisine. We also use a panel of C(10)-substituted cytisine derivatives to probe the effects of subtle changes in the ligand structure on binding. By comparing our results to those obtained for the well-studied α4β2 subtype, we identify several features of both the receptor and agonist structure that can be utilized to enhance selectivity for either α3β4 or α4β2. Finally, we characterize binding interactions of the α3β4-selective partial agonist AT-1001 to determine factors that contribute to its selectivity. These results shed new light on the design of selective nAChR-targeted ligands and can be used to inform the design of improved therapies with minimized off-target effects.
Collapse
Affiliation(s)
- Hailey J Knox
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | | | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | | | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| |
Collapse
|
47
|
Gabriel AAG, Atkins JR, Penha RCC, Smith-Byrne K, Gaborieau V, Voegele C, Abedi-Ardekani B, Milojevic M, Olaso R, Meyer V, Boland A, Deleuze JF, Zaridze D, Mukeriya A, Swiatkowska B, Janout V, Schejbalová M, Mates D, Stojšić J, Ognjanovic M, Witte JS, Rashkin SR, Kachuri L, Hung RJ, Kar S, Brennan P, Sertier AS, Ferrari A, Viari A, Johansson M, Amos CI, Foll M, McKay JD. Genetic Analysis of Lung Cancer and the Germline Impact on Somatic Mutation Burden. J Natl Cancer Inst 2022; 114:1159-1166. [PMID: 35511172 PMCID: PMC9360465 DOI: 10.1093/jnci/djac087] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 01/31/2022] [Accepted: 04/13/2022] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Germline genetic variation contributes to lung cancer (LC) susceptibility. Previous genome-wide association studies (GWAS) have implicated susceptibility loci involved in smoking behaviors and DNA repair genes, but further work is required to identify susceptibility variants. METHODS To identify LC susceptibility loci, a family history-based genome-wide association by proxy (GWAx) of LC (48 843 European proxy LC patients, 195 387 controls) was combined with a previous LC GWAS (29 266 patients, 56 450 controls) by meta-analysis. Colocalization was used to explore candidate genes and overlap with existing traits at discovered susceptibility loci. Polygenic risk scores (PRS) were tested within an independent validation cohort (1 666 LC patients vs 6 664 controls) using variants selected from the LC susceptibility loci and a novel selection approach using published GWAS summary statistics. Finally, the effects of the LC PRS on somatic mutational burden were explored in patients whose tumor resections have been profiled by exome (n = 685) and genome sequencing (n = 61). Statistical tests were 2-sided. RESULTS The GWAx-GWAS meta-analysis identified 8 novel LC loci. Colocalization implicated DNA repair genes (CHEK1), metabolic genes (CYP1A1), and smoking propensity genes (CHRNA4 and CHRNB2). PRS analysis demonstrated that these variants, as well as subgenome-wide significant variants related to expression quantitative trait loci and/or smoking propensity, assisted in LC genetic risk prediction (odds ratio = 1.37, 95% confidence interval = 1.29 to 1.45; P < .001). Patients with higher genetic PRS loads of smoking-related variants tended to have higher mutation burdens in their lung tumors. CONCLUSIONS This study has expanded the number of LC susceptibility loci and provided insights into the molecular mechanisms by which these susceptibility variants contribute to LC development.
Collapse
Affiliation(s)
- Aurélie A G Gabriel
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Joshua R Atkins
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Ricardo C C Penha
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Karl Smith-Byrne
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
- Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, England
| | - Valerie Gaborieau
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Catherine Voegele
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Behnoush Abedi-Ardekani
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Maja Milojevic
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Robert Olaso
- Université Paris-Saclay, The French Alternative Energies and Atomic Energy Commission (CEA), Centre National de Recherche en Génomique Humaine (CNRGH), Evry, France
| | - Vincent Meyer
- Université Paris-Saclay, The French Alternative Energies and Atomic Energy Commission (CEA), Centre National de Recherche en Génomique Humaine (CNRGH), Evry, France
| | - Anne Boland
- Université Paris-Saclay, The French Alternative Energies and Atomic Energy Commission (CEA), Centre National de Recherche en Génomique Humaine (CNRGH), Evry, France
| | - Jean François Deleuze
- Université Paris-Saclay, The French Alternative Energies and Atomic Energy Commission (CEA), Centre National de Recherche en Génomique Humaine (CNRGH), Evry, France
| | - David Zaridze
- Russian N.N. Blokhin Cancer Research Centre, Moscow, Russian Federation
| | - Anush Mukeriya
- Russian N.N. Blokhin Cancer Research Centre, Moscow, Russian Federation
| | - Beata Swiatkowska
- Department of Environmental Epidemiology, Nofer Institute of Occupational Medicine, Lodz, Poland
| | - Vladimir Janout
- Faculty of Medicine, Palacky University, Olomouc, Czech Republic
| | | | - Dana Mates
- National Institute of Public Health, Bucharest, Romania
| | - Jelena Stojšić
- Department of Thoracic Pathology, Service of Pathology, University Clinical Centre of Serbia, Belgrade, Serbia
| | - Miodrag Ognjanovic
- International Organisation for Cancer Prevention and Research, Belgrade, Serbia
| | | | - John S Witte
- Department of Epidemiology & Biostatistics, University of California San Francisco, San Francisco, CA, USA
| | - Sara R Rashkin
- Department of Epidemiology & Biostatistics, University of California San Francisco, San Francisco, CA, USA
- Department of Hematology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Linda Kachuri
- Department of Epidemiology & Biostatistics, University of California San Francisco, San Francisco, CA, USA
| | - Rayjean J Hung
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, Canada
| | - Siddhartha Kar
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Paul Brennan
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Anne-Sophie Sertier
- Fondation Synergie Lyon Cancer, Plateforme de bioinformatique Gilles Thomas, Lyon, France
| | - Anthony Ferrari
- Fondation Synergie Lyon Cancer, Plateforme de bioinformatique Gilles Thomas, Lyon, France
| | - Alain Viari
- Fondation Synergie Lyon Cancer, Plateforme de bioinformatique Gilles Thomas, Lyon, France
- Inria Centre de Recherche Grenoble Rhone-Alpes, Grenoble, France
| | - Mattias Johansson
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - Christopher I Amos
- Institute for Clinical and Translational Research, Baylor College of Medicine, Houston, USA
| | - Matthieu Foll
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| | - James D McKay
- Genomic Epidemiology Branch, International Agency for Research on Cancer/World Health Organization (IARC/WHO), Lyon, France
| |
Collapse
|
48
|
Paramonov AS, Shulepko MA, Makhonin AM, Bychkov ML, Kulbatskii DS, Chernikov AM, Myshkin MY, Shabelnikov SV, Shenkarev ZO, Kirpichnikov MP, Lyukmanova EN. New Three-Finger Protein from Starfish Asteria rubens Shares Structure and Pharmacology with Human Brain Neuromodulator Lynx2. Mar Drugs 2022; 20:md20080503. [PMID: 36005506 PMCID: PMC9410279 DOI: 10.3390/md20080503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 07/27/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
Three-finger proteins (TFPs) are small proteins with characteristic three-finger β-structural fold stabilized by the system of conserved disulfide bonds. These proteins have been found in organisms from different taxonomic groups and perform various important regulatory functions or act as components of snake venoms. Recently, four TFPs (Lystars 1–4) with unknown function were identified in the coelomic fluid proteome of starfish A. rubens. Here we analyzed the genomes of A. rubens and A. planci starfishes and predicted additional five and six proteins containing three-finger domains, respectively. One of them, named Lystar5, is expressed in A. rubens coelomocytes and has sequence homology to the human brain neuromodulator Lynx2. The three-finger structure of Lystar5 close to the structure of Lynx2 was confirmed by NMR. Similar to Lynx2, Lystar5 negatively modulated α4β2 nicotinic acetylcholine receptors (nAChRs) expressed in X. laevis oocytes. Incubation with Lystar5 decreased the expression of acetylcholine esterase and α4 and α7 nAChR subunits in the hippocampal neurons. In summary, for the first time we reported modulator of the cholinergic system in starfish.
Collapse
Affiliation(s)
- Alexander S. Paramonov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
| | - Mikhail A. Shulepko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
| | - Alexey M. Makhonin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
- AI Centre, National Research University Higher School of Economics, Myasnitskaya Str. 20, 101000 Moscow, Russia
| | - Maxim L. Bychkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
| | - Dmitrii S. Kulbatskii
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
| | - Andrey M. Chernikov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
- Interdisciplinary Scientific and Educational School of Moscow University “Molecular Technologies of the Living Systems and Synthetic Biology”, Faculty of Biology, Lomonosov Moscow State University, Leninskie Gory, 119234 Moscow, Russia
| | - Mikhail Yu. Myshkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
| | - Sergey V. Shabelnikov
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Prospect 4, 194064 St. Petersburg, Russia;
| | - Zakhar O. Shenkarev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
- Moscow Institute of Physics and Technology, State University, Institutskiy Per. 9, 141701 Moscow, Russia
| | - Mikhail P. Kirpichnikov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
- Interdisciplinary Scientific and Educational School of Moscow University “Molecular Technologies of the Living Systems and Synthetic Biology”, Faculty of Biology, Lomonosov Moscow State University, Leninskie Gory, 119234 Moscow, Russia
| | - Ekaterina N. Lyukmanova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 119997 Moscow, Russia; (A.S.P.); (M.A.S.); (A.M.M.); (M.L.B.); (D.S.K.); (A.M.C.); (M.Y.M.); (Z.O.S.); (M.P.K.)
- Interdisciplinary Scientific and Educational School of Moscow University “Molecular Technologies of the Living Systems and Synthetic Biology”, Faculty of Biology, Lomonosov Moscow State University, Leninskie Gory, 119234 Moscow, Russia
- Moscow Institute of Physics and Technology, State University, Institutskiy Per. 9, 141701 Moscow, Russia
- Correspondence:
| |
Collapse
|
49
|
Mocatta J, Mesoy SM, Dougherty DA, Lummis SCR. 5-HT 3 Receptor MX Helix Contributes to Receptor Function. ACS Chem Neurosci 2022; 13:2338-2345. [PMID: 35867037 PMCID: PMC9354082 DOI: 10.1021/acschemneuro.2c00339] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
![]()
5-HT3 receptors are members of the family
of pentameric
ligand-gated ion channels. Each subunit has an extracellular, transmembrane,
and intracellular domain. Only part of the intracellular domain structure
has been solved, revealing it contains two α-helical segments;
one, the MA helix, is an extension of M4, while the other, the MX
helix, is formed from residues located close to the end of M3. This
MX helix is in distinct locations in open and closed receptor structures,
suggesting it may play a role in function. Here, we explore this hypothesis
using functional responses of Ala-substituted mutant receptors expressed
in HEK293 cells. The data show altering many of the MX residues results
in a small decrease in EC50 (up to 5-fold), although in
one (H232A) this is increased. Radiolabeled ligand binding on selected
mutants showed no change in binding affinity, indicating an effect
on gating and not binding. In addition, five mutations (P316A, V317A,
P318A, D319A, and H323A) initially resulted in nonfunctional receptors,
but the function could be rescued by coexpression with a chaperone
protein, suggesting a likely role in assembly or folding. Examination
of previously obtained MD simulation data shows that the extent of
MX encompassed by membrane lipids differs considerably in the open
and closed structures, suggesting that lipid–protein interactions
in this region could have a major effect on channel opening propensity.
We conclude that the MX helix can modulate the function of the receptor
and propose that its interactions with membrane lipids play a major
role in this.
Collapse
Affiliation(s)
- James Mocatta
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, United Kingdom
| | - Susanne M Mesoy
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, United Kingdom
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Sarah C R Lummis
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, United Kingdom
| |
Collapse
|
50
|
Structural Insights into the Role of β3 nAChR Subunit in the Activation of Nicotinic Receptors. Molecules 2022; 27:molecules27144642. [PMID: 35889515 PMCID: PMC9319688 DOI: 10.3390/molecules27144642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 02/06/2023] Open
Abstract
The β3 subunit of nicotinic acetylcholine receptors (nAChRs) participates in heteropentameric assemblies with some α and other β neuronal subunits forming a plethora of various subtypes, differing in their electrophysiological and pharmacological properties. While β3 has for several years been considered an accessory subunit without direct participation in the formation of functional binding sites, recent electrophysiology data have disputed this notion and indicated the presence of a functional (+) side on the extracellular domain (ECD) of β3. In this study, we present the 2.4 Å resolution crystal structure of the monomeric β3 ECD, which revealed rather distinctive loop C features as compared to those of α nAChR subunits, leading to intramolecular stereochemical hindrance of the binding site cavity. Vigorous molecular dynamics simulations in the context of full length pentameric β3-containing nAChRs, while not excluding the possibility of a β3 (+) binding site, demonstrate that this site cannot efficiently accommodate the agonist nicotine. From the structural perspective, our results endorse the accessory rather than functional role of the β3 nAChR subunit, in accordance with earlier functional studies on β3-containing nAChRs.
Collapse
|