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Souf YM, Lokaj G, Kuruva V, Saed Y, Raviglione D, Brik A, Nicke A, Inguimbert N, Dutertre S. Synthesis and Biological Activity of Novel α-Conotoxins Derived from Endemic Polynesian Cone Snails. Mar Drugs 2023; 21:356. [PMID: 37367681 DOI: 10.3390/md21060356] [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: 05/17/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/28/2023] Open
Abstract
α-Conotoxins are well-known probes for the characterization of the various subtypes of nicotinic acetylcholine receptors (nAChRs). Identifying new α-conotoxins with different pharmacological profiles can provide further insights into the physiological or pathological roles of the numerous nAChR isoforms found at the neuromuscular junction, the central and peripheral nervous systems, and other cells such as immune cells. This study focuses on the synthesis and characterization of two novel α-conotoxins obtained from two species endemic to the Marquesas Islands, namely Conus gauguini and Conus adamsonii. Both species prey on fish, and their venom is considered a rich source of bioactive peptides that can target a wide range of pharmacological receptors in vertebrates. Here, we demonstrate the versatile use of a one-pot disulfide bond synthesis to achieve the α-conotoxin fold [Cys 1-3; 2-4] for GaIA and AdIA, using the 2-nitrobenzyl (NBzl) protecting group of cysteines for effective regioselective oxidation. The potency and selectivity of GaIA and AdIA against rat nicotinic acetylcholine receptors were investigated electrophysiologically and revealed potent inhibitory activities. GaIA was most active at the muscle nAChR (IC50 = 38 nM), whereas AdIA was most potent at the neuronal α6/3 β2β3 subtype (IC50 = 177 nM). Overall, this study contributes to a better understanding of the structure-activity relationships of α-conotoxins, which may help in the design of more selective tools.
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Affiliation(s)
- Yazid Mohamed Souf
- CRIOBE, UAR CNRS-EPHE-UPVD 3278, Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860 Perpignan, France
| | - Gonxhe Lokaj
- Faculty of Medicine, Walther Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Nußbaumstraße 26, 80336 Munich, Germany
| | - Veeresh Kuruva
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - Yakop Saed
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - Delphine Raviglione
- CRIOBE, UAR CNRS-EPHE-UPVD 3278, Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860 Perpignan, France
| | - Ashraf Brik
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - Annette Nicke
- Faculty of Medicine, Walther Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Nußbaumstraße 26, 80336 Munich, Germany
| | - Nicolas Inguimbert
- CRIOBE, UAR CNRS-EPHE-UPVD 3278, Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860 Perpignan, France
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2
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Wei N, Chu Y, Liu H, Xu Q, Jiang T, Yu R. Antagonistic Mechanism of α-Conotoxin BuIA toward the Human α3β2 Nicotinic Acetylcholine Receptor. ACS Chem Neurosci 2021; 12:4535-4545. [PMID: 34738810 DOI: 10.1021/acschemneuro.1c00568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that are abundantly expressed in the central and peripheral nervous systems, playing an important role in mediating neurotransmitter release and inter-synaptic signaling. Dysfunctional nAChRs are associated with neurological disorders, and studying the structure and function of nAChRs is essential for development of drugs or strategies for treatment of related diseases. α-Conotoxins are selective antagonists of the nAChR and are an important class of drug leads. So far, the antagonistic mechanism of α-conotoxins toward the nAChRs is still unclear. In this study, we built an α3β2 nAChR homology model and investigated its conformational transition mechanism upon binding with a highly potent inhibitor, α-conotoxin BuIA, through μs molecular dynamic simulations and site-directed mutagenesis studies. The results suggested that the α3β2 nAChR underwent global conformational transitions and was stabilized into a closed state with three hydrophobic gates present in the transmembrane domain by BuIA. Finally, the probable antagonistic mechanism of BuIA was proposed. Overall, the closed-state model of the α3β2 nAChR bound with BuIA is not only essential for understanding the antagonistic mechanism of α-conotoxins but also particularly valuable for development of therapeutic inhibitors in future.
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Affiliation(s)
- Ningning Wei
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, China
| | - Yanyan Chu
- Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266200, China
- Molecular Synthesis Center & Key Laboratory of Marine Drugs, Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
- Innovation Platform of Marine Drug Screening & Evaluation, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, Shandong 266100, China
| | - Huijie Liu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, China
| | - Qingliang Xu
- Molecular Synthesis Center & Key Laboratory of Marine Drugs, Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Tao Jiang
- Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266200, China
- Molecular Synthesis Center & Key Laboratory of Marine Drugs, Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Rilei Yu
- Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266200, China
- Molecular Synthesis Center & Key Laboratory of Marine Drugs, Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
- Innovation Platform of Marine Drug Screening & Evaluation, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, Shandong 266100, China
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3
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Donvito G, Muldoon PP, Jackson KJ, Ahmad U, Zaveri NT, McIntosh JM, Chen X, Lichtman AH, Damaj MI. Neuronal nicotinic acetylcholine receptors mediate ∆ 9 -THC dependence: Mouse and human studies. Addict Biol 2020; 25:e12691. [PMID: 30378732 PMCID: PMC6509006 DOI: 10.1111/adb.12691] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/27/2018] [Accepted: 10/09/2018] [Indexed: 11/29/2022]
Abstract
Cessation from prolonged use of ∆9 -tetrahydrocannabinol (THC), the primary active compound responsible for the cannabimimetic effects of cannabis, results in a mild to moderate withdrawal syndrome in humans and laboratory animals. Whereas manipulations of the endogenous cannabinoid system (eg, cannabinoid receptors and endocannabinoid regulating enzymes) alter nicotine withdrawal, in this study we asked the reciprocal question. Do nicotinic acetylcholine receptors (nAChRs) modulate THC withdrawal? To assess the role of different nAChR subtypes in THC withdrawal, we used transgenic mouse, preclinical pharmacological, and human genetic correlation approaches. Our findings show that selective α3β4* nAChR antagonist, AuIB, and α3β4* nAChR partial agonist, AT-1001, dose-dependently attenuated somatic withdrawal signs in THC-dependent mice that were challenged with the cannabinoid-1 receptor antagonist rimonabant. Additionally, THC-dependent α5 and α6 nAChR knockout (KO) mice displayed decreased rimonabant precipitated somatic withdrawal signs compared with their wild-type counterparts. In contrast, β2 and α7 nAChR KO mice showed no alterations in THC withdrawal signs. Moreover, deletion of β2 nAChR did not alter the reduced expression of somatic signs by the preferred α6β4* antagonist, BulA [T5A;P60]. Finally, the human genetic association studies indicated that variations in the genes that code for the α5, α3, β4, and α6 nAChRs were associated with cannabis disorder phenotypes. Overall, these findings suggest that α3β4* and α6β4* nAChR subtypes represent viable targets for the development of medications to counteract THC dependence.
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Affiliation(s)
- Giulia Donvito
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
| | - Pretal P. Muldoon
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
| | - Kia J. Jackson
- Department of Psychiatry, Virginia Commonwealth University, 800 E. Leigh St, Biotech I, Suite 390A, Richmond, VA, 23219, USA
| | - Urslan Ahmad
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
| | - Nur T. Zaveri
- Astraea Therapeutics, LLC. 320 Logue Avenue, Mountain View, CA 94043
| | - J. Michael McIntosh
- Departments of Biology and Psychiatry, University of Utah, Salt Lake City, UT 84112, USA
| | - Xiangning Chen
- Nevada Institute of Personalized Medicine, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy. Las Vegas, NV 89154-4004
| | - Aron H. Lichtman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
| | - M. Imad Damaj
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 1220 E. Broad St., Molecular Medicine Research Building, Box 980613, Richmond, VA, 23298, USA
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4
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Jin AH, Muttenthaler M, Dutertre S, Himaya SWA, Kaas Q, Craik DJ, Lewis RJ, Alewood PF. Conotoxins: Chemistry and Biology. Chem Rev 2019; 119:11510-11549. [PMID: 31633928 DOI: 10.1021/acs.chemrev.9b00207] [Citation(s) in RCA: 161] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The venom of the marine predatory cone snails (genus Conus) has evolved for prey capture and defense, providing the basis for survival and rapid diversification of the now estimated 750+ species. A typical Conus venom contains hundreds to thousands of bioactive peptides known as conotoxins. These mostly disulfide-rich and well-structured peptides act on a wide range of targets such as ion channels, G protein-coupled receptors, transporters, and enzymes. Conotoxins are of interest to neuroscientists as well as drug developers due to their exquisite potency and selectivity, not just against prey but also mammalian targets, thereby providing a rich source of molecular probes and therapeutic leads. The rise of integrated venomics has accelerated conotoxin discovery with now well over 10,000 conotoxin sequences published. However, their structural and pharmacological characterization lags considerably behind. In this review, we highlight the diversity of new conotoxins uncovered since 2014, their three-dimensional structures and folds, novel chemical approaches to their syntheses, and their value as pharmacological tools to unravel complex biology. Additionally, we discuss challenges and future directions for the field.
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Affiliation(s)
- Ai-Hua Jin
- Institute for Molecular Bioscience , The University of Queensland , Brisbane Queensland 4072 , Australia
| | - Markus Muttenthaler
- Institute for Molecular Bioscience , The University of Queensland , Brisbane Queensland 4072 , Australia.,Institute of Biological Chemistry, Faculty of Chemistry , University of Vienna , 1090 Vienna , Austria
| | - Sebastien Dutertre
- Département des Acides Amines, Peptides et Protéines, Unité Mixte de Recherche 5247, Université Montpellier 2-Centre Nationale de la Recherche Scientifique , Institut des Biomolécules Max Mousseron , Place Eugène Bataillon , 34095 Montpellier Cedex 5 , France
| | - S W A Himaya
- Institute for Molecular Bioscience , The University of Queensland , Brisbane Queensland 4072 , Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience , The University of Queensland , Brisbane Queensland 4072 , Australia
| | - David J Craik
- Institute for Molecular Bioscience , The University of Queensland , Brisbane Queensland 4072 , Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience , The University of Queensland , Brisbane Queensland 4072 , Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience , The University of Queensland , Brisbane Queensland 4072 , Australia
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5
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Zouridakis M, Papakyriakou A, Ivanov IA, Kasheverov IE, Tsetlin V, Tzartos S, Giastas P. Crystal Structure of the Monomeric Extracellular Domain of α9 Nicotinic Receptor Subunit in Complex With α-Conotoxin RgIA: Molecular Dynamics Insights Into RgIA Binding to α9α10 Nicotinic Receptors. Front Pharmacol 2019; 10:474. [PMID: 31118896 PMCID: PMC6504684 DOI: 10.3389/fphar.2019.00474] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/15/2019] [Indexed: 12/20/2022] Open
Abstract
The α9 subunit of nicotinic acetylcholine receptors (nAChRs) exists mainly in heteropentameric assemblies with α10. Accumulating data indicate the presence of three different binding sites in α9α10 nAChRs: the α9(+)/α9(−), the α9(+)/α10(−), and the α10(+)/α9(−). The major role of the principal (+) side of the extracellular domain (ECD) of α9 subunit in binding of the antagonists methyllylcaconitine and α-bungarotoxin was shown previously by the crystal structures of the monomeric α9-ECD with these molecules. Here we present the 2.26-Å resolution crystal structure of α9-ECD in complex with α-conotoxin (α-Ctx) RgIA, a potential drug for chronic pain, the first structure reported for a complex between an nAChR domain and an α-Ctx. Superposition of this structure with those of other α-Ctxs bound to the homologous pentameric acetylcholine binding proteins revealed significant similarities in the orientation of bound conotoxins, despite the monomeric state of the α9-ECD. In addition, ligand-binding studies calculated a binding affinity of RgIA to the α9-ECD at the low micromolar range. Given the high identity between α9 and α10 ECDs, particularly at their (+) sides, the presented structure was used as template for molecular dynamics simulations of the ECDs of the human α9α10 nAChR in pentameric assemblies. Our results support a favorable binding of RgIA at α9(+)/α9(−) or α10(+)/α9(−) rather than the α9(+)/α10(−) interface, in accordance with previous mutational and functional data.
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Affiliation(s)
- Marios Zouridakis
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
| | | | - Igor A Ivanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Igor E Kasheverov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
| | - Victor Tsetlin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,PhysBio of MEPhI, Moscow, Russia
| | - Socrates Tzartos
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece.,Department of Pharmacy, University of Patras, Patras, Greece
| | - Petros Giastas
- Department of Neurobiology, Hellenic Pasteur Institute, Athens, Greece
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6
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Mansbach RA, Travers T, McMahon BH, Fair JM, Gnanakaran S. Snails In Silico: A Review of Computational Studies on the Conopeptides. Mar Drugs 2019; 17:E145. [PMID: 30832207 PMCID: PMC6471681 DOI: 10.3390/md17030145] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/21/2019] [Accepted: 02/22/2019] [Indexed: 12/26/2022] Open
Abstract
Marine cone snails are carnivorous gastropods that use peptide toxins called conopeptides both as a defense mechanism and as a means to immobilize and kill their prey. These peptide toxins exhibit a large chemical diversity that enables exquisite specificity and potency for target receptor proteins. This diversity arises in terms of variations both in amino acid sequence and length, and in posttranslational modifications, particularly the formation of multiple disulfide linkages. Most of the functionally characterized conopeptides target ion channels of animal nervous systems, which has led to research on their therapeutic applications. Many facets of the underlying molecular mechanisms responsible for the specificity and virulence of conopeptides, however, remain poorly understood. In this review, we will explore the chemical diversity of conopeptides from a computational perspective. First, we discuss current approaches used for classifying conopeptides. Next, we review different computational strategies that have been applied to understanding and predicting their structure and function, from machine learning techniques for predictive classification to docking studies and molecular dynamics simulations for molecular-level understanding. We then review recent novel computational approaches for rapid high-throughput screening and chemical design of conopeptides for particular applications. We close with an assessment of the state of the field, emphasizing important questions for future lines of inquiry.
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Affiliation(s)
- Rachael A Mansbach
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Timothy Travers
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Benjamin H McMahon
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Jeanne M Fair
- Biosecurity and Public Health Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - S Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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7
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Abalde S, Tenorio MJ, Afonso CML, Zardoya R. Conotoxin Diversity in Chelyconus ermineus (Born, 1778) and the Convergent Origin of Piscivory in the Atlantic and Indo-Pacific Cones. Genome Biol Evol 2018; 10:2643-2662. [PMID: 30060147 PMCID: PMC6178336 DOI: 10.1093/gbe/evy150] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2018] [Indexed: 12/27/2022] Open
Abstract
The transcriptome of the venom duct of the Atlantic piscivorous cone species Chelyconus ermineus (Born, 1778) was determined. The venom repertoire of this species includes at least 378 conotoxin precursors, which could be ascribed to 33 known and 22 new (unassigned) protein superfamilies, respectively. Most abundant superfamilies were T, W, O1, M, O2, and Z, accounting for 57% of all detected diversity. A total of three individuals were sequenced showing considerable intraspecific variation: each individual had many exclusive conotoxin precursors, and only 20% of all inferred mature peptides were common to all individuals. Three different regions (distal, medium, and proximal with respect to the venom bulb) of the venom duct were analyzed independently. Diversity (in terms of number of distinct members) of conotoxin precursor superfamilies increased toward the distal region whereas transcripts detected toward the proximal region showed higher expression levels. Only the superfamilies A and I3 showed statistically significant differential expression across regions of the venom duct. Sequences belonging to the alpha (motor cabal) and kappa (lightning-strike cabal) subfamilies of the superfamily A were mainly detected in the proximal region of the venom duct. The mature peptides of the alpha subfamily had the α4/4 cysteine spacing pattern, which has been shown to selectively target muscle nicotinic-acetylcholine receptors, ultimately producing paralysis. This function is performed by mature peptides having a α3/5 cysteine spacing pattern in piscivorous cone species from the Indo-Pacific region, thereby supporting a convergent evolution of piscivory in cones.
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Affiliation(s)
- Samuel Abalde
- Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
| | - Manuel J Tenorio
- Departamento CMIM y Q. Inorgánica-INBIO, Facultad de Ciencias, Universidad de Cadiz, Puerto Real, Spain
| | - Carlos M L Afonso
- Fisheries, Biodiversity and Conervation Group, Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Rafael Zardoya
- Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
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8
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Tabassum N, Tae HS, Jia X, Kaas Q, Jiang T, Adams DJ, Yu R. Role of Cys I-Cys III Disulfide Bond on the Structure and Activity of α-Conotoxins at Human Neuronal Nicotinic Acetylcholine Receptors. ACS OMEGA 2017; 2:4621-4631. [PMID: 30023726 PMCID: PMC6044955 DOI: 10.1021/acsomega.7b00639] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/04/2017] [Indexed: 06/08/2023]
Abstract
α-Conotoxins preferentially antagonize muscle and neuronal nicotinic acetylcholine receptors (nAChRs). Native α-conotoxins have two disulfide links, CI-CIII and CII-CIV, and owing to the inherent properties of disulfide bonds, α-conotoxins have been systematically engineered to improve their chemical and biological properties. In this study, we explored the possibility of simplifying the disulfide framework of α-conotoxins Vc1.1, BuIA, ImI, and AuIB, by introducing [C2H,C8F] modification to the CI-CIII bond. We therefore explored the possibility of using hydrophobic packing of standard amino acid side chains to replace disulfide bonds as an alternative strategy to nonnatural amino acid cross-links. The impact of CI-CIII disulfide bond replacement on the conformation of the α-conotoxins was investigated using molecular dynamics (MD) simulations and nuclear magnetic resonance chemical shift index study. Two-electrode voltage clamp techniques and MD simulations were used to study the impact of disulfide bond deletion on the activities of the peptides at human neuronal nAChRs. All disulfide-deleted variants except ImI[C2H,C8F] had reduced potency for inhibiting nAChRs. Our results suggest that the CI-CIII disulfide bond is important to stabilize the secondary structure of α-conotoxins as well as their interaction with neuronal nAChR targets. Results from this study enrich our understanding of the function of the CI-CIII disulfide bond and are useful in guiding future structural engineering of the α-conotoxins.
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Affiliation(s)
- Nargis Tabassum
- Key
Laboratory of Marine Drugs, Chinese Ministry of Education, School
of Medicine and Pharmacy, Ocean University
of China, Qingdao 266003, China
- Laboratory
for Marine Drugs and Bioproducts of Qingdao National Laboratory for
Marine Science and Technology, Qingdao 266003, China
| | - Han-Shen Tae
- Illawarra
Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Xinying Jia
- The Centre for Advanced Imaging and Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - Quentin Kaas
- The Centre for Advanced Imaging and Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - Tao Jiang
- Key
Laboratory of Marine Drugs, Chinese Ministry of Education, School
of Medicine and Pharmacy, Ocean University
of China, Qingdao 266003, China
| | - David J. Adams
- Illawarra
Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Rilei Yu
- Key
Laboratory of Marine Drugs, Chinese Ministry of Education, School
of Medicine and Pharmacy, Ocean University
of China, Qingdao 266003, China
- Laboratory
for Marine Drugs and Bioproducts of Qingdao National Laboratory for
Marine Science and Technology, Qingdao 266003, China
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9
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Chang YP, Banerjee J, Dowell C, Wu J, Gyanda R, Houghten RA, Toll L, McIntosh JM, Armishaw CJ. Discovery of a potent and selective α3β4 nicotinic acetylcholine receptor antagonist from an α-conotoxin synthetic combinatorial library. J Med Chem 2014; 57:3511-21. [PMID: 24649848 PMCID: PMC4358631 DOI: 10.1021/jm500183r] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
α-Conotoxins are disulfide-rich peptide neurotoxins that selectively inhibit neuronal nicotinic acetylcholine receptors (nAChRs). The α3β4 nAChR subtype has been identified as a novel target for managing nicotine addiction. Using a mixture-based positional-scanning synthetic combinatorial library (PS-SCL) with the α4/4-conotoxin BuIA framework, we discovered a highly potent and selective α3β4 nAChR antagonist. The initial PS-SCL consisted of a total of 113 379 904 sequences that were screened for α3β4 nAChR inhibition, which facilitated the design and synthesis of a second generation library of 64 individual α-conotoxin derivatives. Eleven analogues were identified as α3β4 nAChR antagonists, with TP-2212-59 exhibiting the most potent antagonistic activity and selectivity over the α3β2 and α4β2 nAChR subtypes. Final electrophysiological characterization demonstrated that TP-2212-59 inhibited acetylcholine evoked currents in α3β4 nAChRs heterogeneously expressed in Xenopus laevis oocytes with a calculated IC50 of 2.3 nM and exhibited more than 1000-fold selectivity over the α3β2 and α7 nAChR subtypes. As such, TP-2212-59 is among the most potent α3β4 nAChRs antagonists identified to date and further demonstrates the utility of mixture-based combinatorial libraries in the discovery of novel α-conotoxin derivatives with refined pharmacological activity.
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Affiliation(s)
- Yi-Pin Chang
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
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10
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Azarn L, Maskos U, Changeux JP, Dowell CD, Christensen S, Biasi MD, McIntosh JM. α‐Conotoxin BuIA[T5A;P6O]: a novel ligand that discriminates between 06 β4 and 0:6 β2 nicotinic acetylcholine receptors and blocks nicotine‐stimulated norepinephrine release. FASEB J 2010. [DOI: 10.1096/fj.10.166272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Layla Azarn
- Department of BiologyUniversity of Utah, Salt Lake City Utah USA
| | - Uwe Maskos
- Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur Paris France
| | - Jean-Pierre Changeux
- Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur Paris France
| | - Cheryl D. Dowell
- Department of BiologyUniversity of Utah, Salt Lake City Utah USA
| | - Sean Christensen
- Department of BiologyUniversity of Utah, Salt Lake City Utah USA
| | - Mariella De Biasi
- Department of Neuroscience and Graduate Program in Translational Biology and Molecular MedicineBaylor College of Medicine Houston Texas USA
| | - J. Michael McIntosh
- Department of BiologyUniversity of Utah, Salt Lake City Utah USA
- Department of PsychiatryUniversity of Utah, Salt Lake City Utah USA
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11
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Azam L, Maskos U, Changeux JP, Dowell CD, Christensen S, De Biasi M, McIntosh JM. α-Conotoxin BuIA[T5A;P6O]: a novel ligand that discriminates between α6ß4 and α6ß2 nicotinic acetylcholine receptors and blocks nicotine-stimulated norepinephrine release. FASEB J 2010; 24:5113-23. [PMID: 20739611 DOI: 10.1096/fj.10-166272] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
α6* (asterisk indicates the presence of additional subunits) nicotinic acetylcholine receptors (nAChRs) are broadly implicated in catecholamine-dependent disorders that involve attention, motor movement, and nicotine self-administration. Different molecular forms of α6 nAChRs mediate catecholamine release, but receptor differentiation is greatly hampered by a paucity of subtype selective ligands. α-Conotoxins are nAChR-targeted peptides used by Conus species to incapacitate prey. We hypothesized that distinct conotoxin-binding kinetics could be exploited to develop a series of selective probes to enable study of native receptor subtypes. Proline6 of α-conotoxin BuIA was found to be critical for nAChR selectivity; substitution of proline6 with 4-hydroyxproline increased the IC(50) by 2800-fold at α6/α3β2β3 but only by 6-fold at α6/α3β4 nAChRs (to 1300 and 12 nM, respectively). We used conotoxin probes together with subunit-null mice to interrogate nAChR subtypes that modulate hippocampal norepinephrine release. Release was abolished in α6-null mutant mice. α-Conotoxin BuIA[T5A;P6O] partially blocked norepinephrine release in wild-type controls but failed to block release in β4(-/-) mice. In contrast, BuIA[T5A;P6O] failed to block dopamine release in the wild-type striatum known to contain α6β2* nAChRs. BuIA[T5A;P6O] is a novel ligand for distinguishing between closely related α6* nAChRs; α6β4* nAChRs modulate norepinephrine release in hippocampus but not dopamine release in striatum.
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Affiliation(s)
- Layla Azam
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
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Kaas Q, Westermann JC, Craik DJ. Conopeptide characterization and classifications: an analysis using ConoServer. Toxicon 2010; 55:1491-509. [PMID: 20211197 DOI: 10.1016/j.toxicon.2010.03.002] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 02/25/2010] [Accepted: 03/01/2010] [Indexed: 10/19/2022]
Abstract
Cone snails are carnivorous marine gastropods that have evolved potent venoms to capture their prey. These venoms comprise a rich and diverse cocktail of peptide toxins, or conopeptides, whose high diversity has arisen from an efficient hypermutation mechanism, combined with a high frequency of post-translational modifications. Conopeptides bind with high specificity to distinct membrane receptors, ion channels, and transporters of the central and muscular nervous system. As well as serving their natural function in prey capture, conopeptides have been utilized as versatile tools in neuroscience and have proven valuable as drug leads that target the nervous system in humans. This paper examines current knowledge on conopeptide sequences based on an analysis of gene and peptide sequences in ConoServer (http://www.conoserver.org), a specialized database of conopeptide sequences and three-dimensional structures. We describe updates to the content and organization of ConoServer and discuss correlations between gene superfamilies, cysteine frameworks, pharmacological families targeted by conopeptides, and the phylogeny, habitat, and diet of cone snails. The study identifies gaps in current knowledge of conopeptides and points to potential directions for future research.
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Affiliation(s)
- Quentin Kaas
- The University of Queensland, Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, Brisbane, 4072 QLD, Australia
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Peng C, Chen W, Han Y, Sanders T, Chew G, Liu J, Hawrot E, Chi C, Wang C. Characterization of a novel alpha4/4-conotoxin, Qc1.2, from vermivorous Conus quercinus. Acta Biochim Biophys Sin (Shanghai) 2009; 41:858-64. [PMID: 19779652 DOI: 10.1093/abbs/gmp077] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
As part of continuing studies of the identification of gene organization and cloning of novel alpha-conotoxins, the first alpha4/4-conotoxin identified in a vermivorous Conus species, designated Qc1.2, was originally obtained by cDNA and genomic DNA cloning from Conus quercinus collected in the South China Sea. The predicted mature toxin of Qc1.2 contains 14 amino acid residues with two disulfide bonds (I-III, II-IV connectivity) in a native globular configuration. The mature peptide of Qc1.2 is supposed to contain an N-terminal post-translationally processed pyroglutamate residue and a free carboxyl C-terminus. This peptide was chemically synthesized and refolded for further characterization of its functional properties. The synthetic Qc1.2 has two interconvertible conformations in aqueous solution, which may be due to the cis-trans isomerization of the two successive Pro residues in its first Cys loop. Using the Xenopus oocyte heterologous expression system, Qc1.2 was shown to selectively inhibit both rat neuronal alpha3beta2 and alpha3beta4 subtypes of nicotinic acetylcholine receptors with low potency. A block of about 63% and 37% of the ACh-evoked currents was observed, respectively, and the toxin dissociated rapidly from the receptors. Compared with other characterized alpha-conotoxin members, the unusual structural features in Qc1.2 that confer to its receptor recognition profile are addressed.
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Affiliation(s)
- Can Peng
- Institute of Protein Research, Tongji University, Shanghai, China
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Alpha-conotoxins as pharmacological probes of nicotinic acetylcholine receptors. Acta Pharmacol Sin 2009; 30:771-83. [PMID: 19448650 DOI: 10.1038/aps.2009.47] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Cysteine-rich peptides from the venom of cone snails (Conus) target a wide variety of different ion channels. One family of conopeptides, the alpha-conotoxins, specifically target different isoforms of nicotinic acetylcholine receptors (nAChRs) found both in the neuromuscular junction and central nervous system. This family is further divided into subfamilies based on the number of amino acids between cysteine residues. The exquisite subtype selectivity of certain alpha-conotoxins has been key to the characterization of native nAChR isoforms involved in modulation of neurotransmitter release, the pathophysiology of Parkinson's disease and nociception. Structure/function characterization of alpha-conotoxins has led to the development of analogs with improved potency and/or subtype selectivity. Cyclization of the backbone structure and addition of lipophilic moieties has led to improved stability and bioavailability of alpha-conotoxins, thus paving the way for orally available therapeutics. The recent advances in phylogeny, exogenomics and molecular modeling promises the discovery of an even greater number of alpha-conotoxins and analogs with improved selectivity for specific subtypes of nAChRs.
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Mysterious alpha6-containing nAChRs: function, pharmacology, and pathophysiology. Acta Pharmacol Sin 2009; 30:740-51. [PMID: 19498417 DOI: 10.1038/aps.2009.63] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are the superfamily of ligand-gated ion channels and widely expressed throughout the central and peripheral nervous systems. nAChRs play crucial roles in modulating a wide range of higher cognitive functions by mediating presynaptic, postsynaptic, and extrasynaptic signaling. Thus far, nine alpha (alpha2-alpha10) and three beta (beta2, beta3, and beta4) subunits have been identified in the CNS, and these subunits assemble to form a diversity of functional nAChRs. Although alpha4beta2- and alpha7-nAChRs are the two major functional nAChR types in the CNS, alpha6*-nAChRs are abundantly expressed in the midbrain dopaminergic (DAergic) system, including mesocorticolimbic and nigrostriatal pathways, and particularly present in presynaptic nerve terminals. Recently, functional and pharmacological profiles of alpha6*-nAChRs have been assessed with the use of alpha6 subunit blockers such as alpha-conotoxin MII and PIA, and also by using alpha6 subunit knockout mice. By modulating DA release in the nucleus accumbens (NAc) and modulating GABA release onto DAergic neurons in the ventral tegmental area (VTA), alpha6*-nAChRs may play important roles in the mediation of nicotine reward and addiction. Furthermore, alpha6*-nAChRs in the nigrostriatal DAergic system may be promising targets for selective preventative treatment of Parkinson's disease (PD). Thus, alpha6*-nAChRs may hold promise for future clinical treatment of human disorders, such as nicotine addiction and PD. In this review, we mainly focus on the recent advances in the understanding of alpha6*-nAChR function, pharmacology and pathophysiology.
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Abstract
Conotoxins are small disulfide-rich peptides from the venoms of marine cone snails. They target a variety of ion channels, transporters, and receptors besides the interest in their natural functions in venoms and they are of much interest as drug leads. This short article gives an overview of the structural diversity of conotoxins, and illustrates this diversity with recent selected examples of conotoxin structures.
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Affiliation(s)
- Norelle L Daly
- The University of Queensland, Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, Brisbane, QLD, Australia.
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Jin AH, Daly NL, Nevin ST, Wang CIA, Dutertre S, Lewis RJ, Adams DJ, Craik DJ, Alewood PF. Molecular engineering of conotoxins: the importance of loop size to alpha-conotoxin structure and function. J Med Chem 2008; 51:5575-84. [PMID: 18754612 DOI: 10.1021/jm800278k] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Alpha-conotoxins are competitive antagonists of nicotinic acetylcholine receptors (nAChRs). The majority of currently characterized alpha-conotoxins have a 4/7 loop size, and the major features of neuronal alpha-conotoxins include a globular disulfide connectivity and a helical structure centered around the third of their four cysteine residues. In this study, a novel "molecular pruning" approach was undertaken to define the relationship between loop size, structure, and function of alpha-conotoxins. This involved the systematic truncation of the second loop in the alpha-conotoxin [A10L]PnIA [4/7], a potent antagonist of the alpha7 nAChR. The penalty for truncation was found to be decreased conformational stability and increased susceptibility to disulfide bond scrambling. Truncation down to 4/4[A10L]PnIA maintained helicity and did not significantly reduce electrophysiological activity at alpha7 nAChRs, whereas 4/3[A10L]PnIA lost both alpha7 nAChR activity and helicity. In contrast, all truncated analogues lost approximately 100-fold affinity at the AChBP, a model protein for the extracellular domain of the nAChR. Docking simulations identified several hydrogen bonds lost upon truncation that provide an explanation for the reduced affinities observed at the alpha7 nAChR and AChBP.
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Affiliation(s)
- Ai-Hua Jin
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072 Australia
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Structure of alpha-conotoxin BuIA: influences of disulfide connectivity on structural dynamics. BMC STRUCTURAL BIOLOGY 2007; 7:28. [PMID: 17445276 PMCID: PMC1865545 DOI: 10.1186/1472-6807-7-28] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 04/20/2007] [Indexed: 12/01/2022]
Abstract
Background α-Conotoxins have exciting therapeutic potential based on their high selectivity and affinity for nicotinic acetylcholine receptors. The spacing between the cysteine residues in α-conotoxins is variable, leading to the classification of sub-families. BuIA is the only α-conotoxin containing a 4/4 cysteine spacing and thus it is of significant interest to examine the structure of this conotoxin. Results In the current study we show the native globular disulfide connectivity of BuIA displays multiple conformations in solution whereas the non-native ribbon isomer has a single well-defined conformation. Despite having multiple conformations in solution the globular form of BuIA displays activity at the nicotinic acetylcholine receptor, contrasting with the lack of activity of the structurally well-defined ribbon isomer. Conclusion These findings are opposite to the general trends observed for α-conotoxins where the native isomers have well-defined structures and the ribbon isomers are generally disordered. This study thus highlights the influence of the disulfide connectivity of BuIA on the dynamics of the three-dimensional structure.
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