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McMahon KL, Vetter I, Schroeder CI. Voltage-Gated Sodium Channel Inhibition by µ-Conotoxins. Toxins (Basel) 2024; 16:55. [PMID: 38251271 PMCID: PMC10819908 DOI: 10.3390/toxins16010055] [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: 11/21/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/23/2024] Open
Abstract
µ-Conotoxins are small, potent pore-blocker inhibitors of voltage-gated sodium (NaV) channels, which have been identified as pharmacological probes and putative leads for analgesic development. A limiting factor in their therapeutic development has been their promiscuity for different NaV channel subtypes, which can lead to undesirable side-effects. This review will focus on four areas of µ-conotoxin research: (1) mapping the interactions of µ-conotoxins with different NaV channel subtypes, (2) µ-conotoxin structure-activity relationship studies, (3) observed species selectivity of µ-conotoxins and (4) the effects of µ-conotoxin disulfide connectivity on activity. Our aim is to provide a clear overview of the current status of µ-conotoxin research.
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Affiliation(s)
- Kirsten L. McMahon
- Institute for Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Irina Vetter
- Institute for Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- The School of Pharmacy, The University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Christina I. Schroeder
- Institute for Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Genentech, 1 DNA Way, South San Francisco, CA 94080, USA
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2
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Groome JR. Historical Perspective of the Characterization of Conotoxins Targeting Voltage-Gated Sodium Channels. Mar Drugs 2023; 21:md21040209. [PMID: 37103349 PMCID: PMC10142487 DOI: 10.3390/md21040209] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/21/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023] Open
Abstract
Marine toxins have potent actions on diverse sodium ion channels regulated by transmembrane voltage (voltage-gated ion channels) or by neurotransmitters (nicotinic acetylcholine receptor channels). Studies of these toxins have focused on varied aspects of venom peptides ranging from evolutionary relationships of predator and prey, biological actions on excitable tissues, potential application as pharmacological intervention in disease therapy, and as part of multiple experimental approaches towards an understanding of the atomistic characterization of ion channel structure. This review examines the historical perspective of the study of conotoxin peptides active on sodium channels gated by transmembrane voltage, which has led to recent advances in ion channel research made possible with the exploitation of the diversity of these marine toxins.
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Affiliation(s)
- James R Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
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3
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Zhorov BS. Molecular Modeling of Cardiac Sodium Channel with Mexiletine. MEMBRANES 2022; 12:1252. [PMID: 36557159 PMCID: PMC9786191 DOI: 10.3390/membranes12121252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/04/2022] [Accepted: 12/06/2022] [Indexed: 05/15/2023]
Abstract
A sodium channel blocker mexiletine (MEX) is used to treat chronic pain, myotonia and some arrhythmias. Mutations in the pore domain (PD) of voltage-gated sodium channels differently affect tonic block (TB) and use-dependent block (UDB) by MEX. Previous studies identified several MEX-sensing residues in the hNav1.5 channel and demonstrated that the channel block by MEX increases with activation of the voltage-sensing domain III (VSDIII), whereas MEX stabilizes the activated state of VSDIII. Structural rationales for these observations are unclear. Here, Monte Carlo (MC) energy minimizations were used to dock MEX and its more potent analog, Thio-Me2, into the hNav1.5 cryo-EM structure with activated VSDs and presumably inactivated PD. Computations yielded two ensembles of ligand binding poses in close contacts with known MEX-sensing residues in helices S6III, S6IV and P1IV. In both ensembles, the ligand NH3 group approached the cation-attractive site between backbone carbonyls at the outer-pore bottom, while the aromatic ring protruded ether into the inner pore (putative UDB pose) or into the III/IV fenestration (putative TB pose). In silico deactivation of VSDIII shifted helices S4-S5III, S5III, S6III and S6IV and tightened the TB site. In a model with activated VSDIII and three resting VSDs, MC-minimized energy profile of MEX pulled from the TB site towards lipids shows a deep local minimum due to interactions with 11 residues in S5III, P1III, S6III and S6IV. The minimum may correspond to an interim binding site for MEX in the hydrophobic path to the TB site along the lipid-exposed sides of repeats III and IV where 15 polar and aromatic residues would attract cationic blockers. The study explains numerous experimental data and suggests the mechanism of allosteric modification of the MEX binding site by VSDIII.
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Affiliation(s)
- Boris S. Zhorov
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada;
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223 St. Petersburg, Russia
- Almazov National Medical Research Centre, 197341 St. Petersburg, Russia
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4
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Pathophysiological Responses to Conotoxin Modulation of Voltage-Gated Ion Currents. Mar Drugs 2022; 20:md20050282. [PMID: 35621933 PMCID: PMC9143252 DOI: 10.3390/md20050282] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 04/04/2022] [Accepted: 04/21/2022] [Indexed: 02/04/2023] Open
Abstract
Voltage-gated ion channels are plasma membrane proteins that generate electrical signals following a change in the membrane voltage. Since they are involved in several physiological processes, their dysfunction may be responsible for a series of diseases and pain states particularly related to neuronal and muscular systems. It is well established for decades that bioactive peptides isolated from venoms of marine mollusks belonging to the Conus genus, collectively known as conotoxins, can target different types and isoforms of these channels exerting therapeutic effects and pain relief. For this reason, conotoxins are widely used for either therapeutic purposes or studies on ion channel mechanisms of action disclosure. In addition their positive property, however, conotoxins may generate pathological states through similar ion channel modulation. In this narrative review, we provide pieces of evidence on the pathophysiological impacts that different members of conotoxin families exert by targeting the three most important voltage-gated channels, such as sodium, calcium, and potassium, involved in cellular processes.
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Louzao MC, Vilariño N, Vale C, Costas C, Cao A, Raposo-Garcia S, Vieytes MR, Botana LM. Current Trends and New Challenges in Marine Phycotoxins. Mar Drugs 2022; 20:md20030198. [PMID: 35323497 PMCID: PMC8950113 DOI: 10.3390/md20030198] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 02/04/2023] Open
Abstract
Marine phycotoxins are a multiplicity of bioactive compounds which are produced by microalgae and bioaccumulate in the marine food web. Phycotoxins affect the ecosystem, pose a threat to human health, and have important economic effects on aquaculture and tourism worldwide. However, human health and food safety have been the primary concerns when considering the impacts of phycotoxins. Phycotoxins toxicity information, often used to set regulatory limits for these toxins in shellfish, lacks traceability of toxicity values highlighting the need for predefined toxicological criteria. Toxicity data together with adequate detection methods for monitoring procedures are crucial to protect human health. However, despite technological advances, there are still methodological uncertainties and high demand for universal phycotoxin detectors. This review focuses on these topics, including uncertainties of climate change, providing an overview of the current information as well as future perspectives.
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Affiliation(s)
- Maria Carmen Louzao
- Departamento de Farmacologia, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain; (N.V.); (C.V.); (C.C.); (A.C.); (S.R.-G.)
- Correspondence: (M.C.L.); (L.M.B.)
| | - Natalia Vilariño
- Departamento de Farmacologia, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain; (N.V.); (C.V.); (C.C.); (A.C.); (S.R.-G.)
| | - Carmen Vale
- Departamento de Farmacologia, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain; (N.V.); (C.V.); (C.C.); (A.C.); (S.R.-G.)
| | - Celia Costas
- Departamento de Farmacologia, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain; (N.V.); (C.V.); (C.C.); (A.C.); (S.R.-G.)
| | - Alejandro Cao
- Departamento de Farmacologia, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain; (N.V.); (C.V.); (C.C.); (A.C.); (S.R.-G.)
| | - Sandra Raposo-Garcia
- Departamento de Farmacologia, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain; (N.V.); (C.V.); (C.C.); (A.C.); (S.R.-G.)
| | - Mercedes R. Vieytes
- Departamento de Fisiologia, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain;
| | - Luis M. Botana
- Departamento de Farmacologia, Facultad de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain; (N.V.); (C.V.); (C.C.); (A.C.); (S.R.-G.)
- Correspondence: (M.C.L.); (L.M.B.)
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6
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Delivery of local anaesthetics by a self-assembled supramolecular system mimicking their interactions with a sodium channel. Nat Biomed Eng 2021; 5:1099-1109. [PMID: 34518656 DOI: 10.1038/s41551-021-00793-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 08/09/2021] [Indexed: 01/04/2023]
Abstract
Site-1 sodium channel blockers (S1SCBs) act as potent local anaesthetics, but they can cause severe systemic toxicity. Delivery systems can be used to reduce the toxicity, but the hydrophilicity of S1SCBs makes their encapsulation challenging. Here, we report a self-assembling delivery system for S1SCBs whose design is inspired by the specific interactions of S1SCBs with two peptide sequences on the sodium channel. Specifically, the peptides were modified with hydrophobic domains so that they could assemble into nanofibres that facilitated specific binding with the S1SCBs tetrodotoxin, saxitoxin and dicarbamoyl saxitoxin. Injection of S1SCB-carrying nanofibres at the sciatic nerves of rats led to prolonged nerve blockade and to reduced systemic toxicity, with benign local-tissue reaction. The strategy of mimicking a molecular binding site via supramolecular interactions may be applicable more broadly to the design of drug delivery systems for receptor-mediated drugs.
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Pesti K, Földi MC, Zboray K, Toth AV, Lukacs P, Mike A. Characterization of Compound-Specific, Concentration-Independent Biophysical Properties of Sodium Channel Inhibitor Mechanism of Action Using Automated Patch-Clamp Electrophysiology. Front Pharmacol 2021; 12:738460. [PMID: 34497526 PMCID: PMC8419314 DOI: 10.3389/fphar.2021.738460] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/10/2021] [Indexed: 01/15/2023] Open
Abstract
We have developed an automated patch-clamp protocol that allows high information content screening of sodium channel inhibitor compounds. We have observed that individual compounds had their specific signature patterns of inhibition, which were manifested irrespective of the concentration. Our aim in this study was to quantify these properties. Primary biophysical data, such as onset rate, the shift of the half inactivation voltage, or the delay of recovery from inactivation, are concentration-dependent. We wanted to derive compound-specific properties, therefore, we had to neutralize the effect of concentration. This study describes how this is done, and shows how compound-specific properties reflect the mechanism of action, including binding dynamics, cooperativity, and interaction with the membrane phase. We illustrate the method using four well-known sodium channel inhibitor compounds, riluzole, lidocaine, benzocaine, and bupivacaine. Compound-specific biophysical properties may also serve as a basis for deriving parameters for kinetic modeling of drug action. We discuss how knowledge about the mechanism of action may help to predict the frequency-dependence of individual compounds, as well as their potential persistent current component selectivity. The analysis method described in this study, together with the experimental protocol described in the accompanying paper, allows screening for inhibitor compounds with specific kinetic properties, or with specific mechanisms of inhibition.
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Affiliation(s)
- Krisztina Pesti
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
- School of Ph.D. Studies, Semmelweis University, Budapest, Hungary
| | - Mátyás C. Földi
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
- Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Katalin Zboray
- Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Adam V. Toth
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
- Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Peter Lukacs
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
- Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Arpad Mike
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
- Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
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8
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Computational Analysis of the Crystal and Cryo-EM Structures of P-Loop Channels with Drugs. Int J Mol Sci 2021; 22:ijms22158143. [PMID: 34360907 PMCID: PMC8348670 DOI: 10.3390/ijms22158143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 12/01/2022] Open
Abstract
The superfamily of P-loop channels includes various potassium channels, voltage-gated sodium and calcium channels, transient receptor potential channels, and ionotropic glutamate receptors. Despite huge structural and functional diversity of the channels, their pore-forming domain has a conserved folding. In the past two decades, scores of atomic-scale structures of P-loop channels with medically important drugs in the inner pore have been published. High structural diversity of these complexes complicates the comparative analysis of these structures. Here we 3D-aligned structures of drug-bound P-loop channels, compared their geometric characteristics, and analyzed the energetics of ligand-channel interactions. In the superimposed structures drugs occupy most of the sterically available space in the inner pore and subunit/repeat interfaces. Cationic groups of some drugs occupy vacant binding sites of permeant ions in the inner pore and selectivity-filter region. Various electroneutral drugs, lipids, and detergent molecules are seen in the interfaces between subunits/repeats. In many structures the drugs strongly interact with lipid and detergent molecules, but physiological relevance of such interactions is unclear. Some eukaryotic sodium and calcium channels have state-dependent or drug-induced π-bulges in the inner helices, which would be difficult to predict. The drug-induced π-bulges may represent a novel mechanism of gating modulation.
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9
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Zhorov BS. Structure of Sodium and Calcium Channels
with Ligands. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021020150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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10
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Zhorov BS. Possible Mechanism of Ion Selectivity in Eukaryotic Voltage-Gated Sodium Channels. J Phys Chem B 2021; 125:2074-2088. [DOI: 10.1021/acs.jpcb.0c11181] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Boris S. Zhorov
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8K 4K1, Canada
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russian Federation
- Almazov National Medical Research Centre, St. Petersburg 197341, Russian Federation
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11
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McMahon KL, Tran HN, Deuis JR, Lewis RJ, Vetter I, Schroeder CI. Discovery, Pharmacological Characterisation and NMR Structure of the Novel µ-Conotoxin SxIIIC, a Potent and Irreversible Na V Channel Inhibitor. Biomedicines 2020; 8:biomedicines8100391. [PMID: 33023152 PMCID: PMC7599555 DOI: 10.3390/biomedicines8100391] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/25/2020] [Accepted: 09/29/2020] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium (NaV) channel subtypes, including NaV1.7, are promising targets for the treatment of neurological diseases, such as chronic pain. Cone snail-derived µ-conotoxins are small, potent NaV channel inhibitors which represent potential drug leads. Of the 22 µ-conotoxins characterised so far, only a small number, including KIIIA and CnIIIC, have shown inhibition against human NaV1.7. We have recently identified a novel µ-conotoxin, SxIIIC, from Conus striolatus. Here we present the isolation of native peptide, chemical synthesis, characterisation of human NaV channel activity by whole-cell patch-clamp electrophysiology and analysis of the NMR solution structure. SxIIIC displays a unique NaV channel selectivity profile (1.4 > 1.3 > 1.1 ≈ 1.6 ≈ 1.7 > 1.2 >> 1.5 ≈ 1.8) when compared to other µ-conotoxins and represents one of the most potent human NaV1.7 putative pore blockers (IC50 152.2 ± 21.8 nM) to date. NMR analysis reveals the structure of SxIIIC includes the characteristic α-helix seen in other µ-conotoxins. Future investigations into structure-activity relationships of SxIIIC are expected to provide insights into residues important for NaV channel pore blocker selectivity and subsequently important for chronic pain drug development.
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Affiliation(s)
- Kirsten L. McMahon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (K.L.M.); (H.N.T.T.); (J.R.D.); (R.J.L.)
| | - Hue N.T. Tran
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (K.L.M.); (H.N.T.T.); (J.R.D.); (R.J.L.)
| | - Jennifer R. Deuis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (K.L.M.); (H.N.T.T.); (J.R.D.); (R.J.L.)
| | - Richard J. Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (K.L.M.); (H.N.T.T.); (J.R.D.); (R.J.L.)
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (K.L.M.); (H.N.T.T.); (J.R.D.); (R.J.L.)
- The School of Pharmacy, The University of Queensland, Woolloongabba, QLD 4102, Australia
- Correspondence: (I.V.); (C.I.S.)
| | - Christina I. Schroeder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (K.L.M.); (H.N.T.T.); (J.R.D.); (R.J.L.)
- National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
- Correspondence: (I.V.); (C.I.S.)
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12
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Gallo A, Boni R, Tosti E. Neurobiological activity of conotoxins via sodium channel modulation. Toxicon 2020; 187:47-56. [PMID: 32877656 DOI: 10.1016/j.toxicon.2020.08.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/20/2020] [Accepted: 08/22/2020] [Indexed: 01/02/2023]
Abstract
Conotoxins (CnTX) are bioactive peptides produced by marine molluscs belonging to Conus genus. The biochemical structure of these venomous peptides is characterized by a low number of amino acids linked with disulfide bonds formed by a high degree of post-translational modifications and glycosylation steps which increase the diversity and rate of evolution of these molecules. CnTX different isoforms are known to target ion channels and, in particular, voltage-gated sodium (Na+) channels (Nav channels). These are transmembrane proteins fundamental in excitable cells for generating the depolarization of plasma membrane potential known as action potential which propagates electrical signals in muscles and nerves for physiological functions. Disorders in Nav channel activity have been shown to induce neurological pathologies and pain states. Here, we describe the current knowledge of CnTX isoform modulation of the Nav channel activity, the mechanism of action and the potential therapeutic use of these toxins in counteracting neurological dysfunctions.
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Affiliation(s)
- Alessandra Gallo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy.
| | - Raffele Boni
- Department of Sciences, University of Basilicata, 85100, Potenza, Italy.
| | - Elisabetta Tosti
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy.
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Conotoxin Diversity in the Venom Gland Transcriptome of the Magician's Cone, Pionoconus magus. Mar Drugs 2019; 17:md17100553. [PMID: 31569823 PMCID: PMC6835573 DOI: 10.3390/md17100553] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 09/24/2019] [Indexed: 12/14/2022] Open
Abstract
The transcriptomes of the venom glands of two individuals of the magician’s cone, Pionoconus magus, from Okinawa (Japan) were sequenced, assembled, and annotated. In addition, RNA-seq raw reads available at the SRA database from one additional specimen of P. magus from the Philippines were also assembled and annotated. The total numbers of identified conotoxin precursors and hormones per specimen were 118, 112, and 93. The three individuals shared only five identical sequences whereas the two specimens from Okinawa had 30 sequences in common. The total number of distinct conotoxin precursors and hormones for P. magus was 275, and were assigned to 53 conotoxin precursor and hormone superfamilies, two of which were new based on their divergent signal region. The superfamilies that had the highest number of precursors were M (42), O1 (34), T (27), A (18), O2 (17), and F (13), accounting for 55% of the total diversity. The D superfamily, previously thought to be exclusive of vermivorous cones was found in P. magus and contained a highly divergent mature region. Similarly, the A superfamily alpha 4/3 was found in P. magus despite the fact that it was previously postulated to be almost exclusive of the genus Rhombiconus. Differential expression analyses of P. magus compared to Chelyconus ermineus, the only fish-hunting cone from the Atlantic Ocean revealed that M and A2 superfamilies appeared to be more expressed in the former whereas the O2 superfamily was more expressed in the latter.
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14
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Finol-Urdaneta RK, McArthur JR, Korkosh VS, Huang S, McMaster D, Glavica R, Tikhonov DB, Zhorov BS, French RJ. Extremely Potent Block of Bacterial Voltage-Gated Sodium Channels by µ-Conotoxin PIIIA. Mar Drugs 2019; 17:md17090510. [PMID: 31470595 PMCID: PMC6780087 DOI: 10.3390/md17090510] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/13/2019] [Accepted: 08/24/2019] [Indexed: 12/15/2022] Open
Abstract
µ-Conotoxin PIIIA, in the sub-picomolar, range inhibits the archetypal bacterial sodium channel NaChBac (NavBh) in a voltage- and use-dependent manner. Peptide µ-conotoxins were first recognized as potent components of the venoms of fish-hunting cone snails that selectively inhibit voltage-gated skeletal muscle sodium channels, thus preventing muscle contraction. Intriguingly, computer simulations predicted that PIIIA binds to prokaryotic channel NavAb with much higher affinity than to fish (and other vertebrates) skeletal muscle sodium channel (Nav 1.4). Here, using whole-cell voltage clamp, we demonstrate that PIIIA inhibits NavBac mediated currents even more potently than predicted. From concentration-response data, with [PIIIA] varying more than 6 orders of magnitude (10−12 to 10−5 M), we estimated an IC50 = ~5 pM, maximal block of 0.95 and a Hill coefficient of 0.81 for the inhibition of peak currents. Inhibition was stronger at depolarized holding potentials and was modulated by the frequency and duration of the stimulation pulses. An important feature of the PIIIA action was acceleration of macroscopic inactivation. Docking of PIIIA in a NaChBac (NavBh) model revealed two interconvertible binding modes. In one mode, PIIIA sterically and electrostatically blocks the permeation pathway. In a second mode, apparent stabilization of the inactivated state was achieved by PIIIA binding between P2 helices and trans-membrane S5s from adjacent channel subunits, partially occluding the outer pore. Together, our experimental and computational results suggest that, besides blocking the channel-mediated currents by directly occluding the conducting pathway, PIIIA may also change the relative populations of conducting (activated) and non-conducting (inactivated) states.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.
- Department of Biochemistry, Brandeis University, Waltham, MA 0254-9110, USA.
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Vyacheslav S Korkosh
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
| | - Sun Huang
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Denis McMaster
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Robert Glavica
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Denis B Tikhonov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
| | - Boris S Zhorov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg 194223, Russia
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8N 4K1, Canada
| | - Robert J French
- Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
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Kudo Y, Yotsu-Yamashita M. Isolation and Biological Activity of 8- Epitetrodotoxin and the Structure of a Possible Biosynthetic Shunt Product of Tetrodotoxin, Cep-226A, from the Newt Cynops ensicauda popei. JOURNAL OF NATURAL PRODUCTS 2019; 82:1656-1663. [PMID: 31117524 DOI: 10.1021/acs.jnatprod.9b00178] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Tetrodotoxin (TTX, 1), a potent neurotoxin, has been found in various animal species in both marine and terrestrial environments. In this study, a new TTX analogue, 8- epiTTX (2), and a possible biosynthetic shunt compound of TTX, Cep-226A (3), were isolated from the newt Cynops ensicauda popei. The voltage-gated sodium ion channel (Nav) blocking activity of 2 and 6- epiTTX (4), a known analogue, were investigated by a colorimetric cell-based assay and compared with that of 1. The EC50 values for 2 and 4 were determined to be 110 ± 40 and 33 ± 11 nM, respectively, which were larger than that of 1 (1.9 ± 0.7 nM). The results indicated that the equatorial hydroxy group at C-8 in TTX significantly contributes to its Nav blocking activity, whereas the 6-epimer of TTX retains substantial activity, consistent with its previously reported toxicity in mice and binding affinity to rat brain membrane preparations. The presence of these epimers of TTX (2 and 4) and Cep-226A (3) in newts supports our hypothesis that TTX is derived from a monoterpene in terrestrial environments.
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Affiliation(s)
- Yuta Kudo
- Graduate School of Agricultural Science , Tohoku University , 468-1 Aramaki-Aza-Aoba, Aoba-ku , Sendai , Miyagi 980-8572 , Japan
- Frontier Research Institute for Interdisciplinary Sciences , Tohoku University , 6-3 Aramaki-Aza-Aoba, Aoba-ku , Sendai , Miyagi 980-8578 , Japan
| | - Mari Yotsu-Yamashita
- Graduate School of Agricultural Science , Tohoku University , 468-1 Aramaki-Aza-Aoba, Aoba-ku , Sendai , Miyagi 980-8572 , Japan
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Morales Duque H, Campos Dias S, Franco OL. Structural and Functional Analyses of Cone Snail Toxins. Mar Drugs 2019; 17:md17060370. [PMID: 31234371 PMCID: PMC6628382 DOI: 10.3390/md17060370] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 06/16/2019] [Accepted: 06/17/2019] [Indexed: 12/12/2022] Open
Abstract
Cone snails are marine gastropod mollusks with one of the most powerful venoms in nature. The toxins, named conotoxins, must act quickly on the cone snails´ prey due to the fact that snails are extremely slow, reducing their hunting capability. Therefore, the characteristics of conotoxins have become the object of investigation, and as a result medicines have been developed or are in the trialing process. Conotoxins interact with transmembrane proteins, showing specificity and potency. They target ion channels and ionotropic receptors with greater regularity, and when interaction occurs, there is immediate physiological decompensation. In this review we aimed to evaluate the structural features of conotoxins and the relationship with their target types.
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Affiliation(s)
- Harry Morales Duque
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
| | - Simoni Campos Dias
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
| | - Octávio Luiz Franco
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
- S-inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande-MS 79.117-900, Brazil.
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Tikhonov DB, Zhorov BS. Intersegment contacts determine geometry of the open and closed states in P-loop channels. J Biomol Struct Dyn 2019; 38:1012-1027. [DOI: 10.1080/07391102.2019.1592026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Denis B. Tikhonov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russian Federation
| | - Boris S. Zhorov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russian Federation
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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18
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Fux JE, Mehta A, Moffat J, Spafford JD. Eukaryotic Voltage-Gated Sodium Channels: On Their Origins, Asymmetries, Losses, Diversification and Adaptations. Front Physiol 2018; 9:1406. [PMID: 30519187 PMCID: PMC6259924 DOI: 10.3389/fphys.2018.01406] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 09/14/2018] [Indexed: 12/19/2022] Open
Abstract
The appearance of voltage-gated, sodium-selective channels with rapid gating kinetics was a limiting factor in the evolution of nervous systems. Two rounds of domain duplications generated a common 24 transmembrane segment (4 × 6 TM) template that is shared amongst voltage-gated sodium (Nav1 and Nav2) and calcium channels (Cav1, Cav2, and Cav3) and leak channel (NALCN) plus homologs from yeast, different single-cell protists (heterokont and unikont) and algae (green and brown). A shared architecture in 4 × 6 TM channels include an asymmetrical arrangement of extended extracellular L5/L6 turrets containing a 4-0-2-2 pattern of cysteines, glycosylated residues, a universally short III-IV cytoplasmic linker and often a recognizable, C-terminal PDZ binding motif. Six intron splice junctions are conserved in the first domain, including a rare U12-type of the minor spliceosome provides support for a shared heritage for sodium and calcium channels, and a separate lineage for NALCN. The asymmetrically arranged pores of 4x6 TM channels allows for a changeable ion selectivity by means of a single lysine residue change in the high field strength site of the ion selectivity filter in Domains II or III. Multicellularity and the appearance of systems was an impetus for Nav1 channels to adapt to sodium ion selectivity and fast ion gating. A non-selective, and slowly gating Nav2 channel homolog in single cell eukaryotes, predate the diversification of Nav1 channels from a basal homolog in a common ancestor to extant cnidarians to the nine vertebrate Nav1.x channel genes plus Nax. A close kinship between Nav2 and Nav1 homologs is evident in the sharing of most (twenty) intron splice junctions. Different metazoan groups have lost their Nav1 channel genes altogether, while vertebrates rapidly expanded their gene numbers. The expansion in vertebrate Nav1 channel genes fills unique functional niches and generates overlapping properties contributing to redundancies. Specific nervous system adaptations include cytoplasmic linkers with phosphorylation sites and tethered elements to protein assemblies in First Initial Segments and nodes of Ranvier. Analogous accessory beta subunit appeared alongside Nav1 channels within different animal sub-phyla. Nav1 channels contribute to pace-making as persistent or resurgent currents, the former which is widespread across animals, while the latter is a likely vertebrate adaptation.
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Affiliation(s)
- Julia E Fux
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Amrit Mehta
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Jack Moffat
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - J David Spafford
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
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