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Characterization, molecular modeling and phylogenetic analysis of a long mammalian neurotoxin from the venom of the Iranian scorpion Androctonus crassicauda. Biologia (Bratisl) 2019. [DOI: 10.2478/s11756-019-00400-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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2
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Animal toxins for channelopathy treatment. Neuropharmacology 2017; 132:83-97. [PMID: 29080794 DOI: 10.1016/j.neuropharm.2017.10.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 10/09/2017] [Accepted: 10/24/2017] [Indexed: 12/18/2022]
Abstract
Ion channels are transmembrane proteins that allow passive flow of ions inside and/or outside of cells or cell organelles. Except mutations lead to nonfunctional protein production or abolished receptor entrance on the membrane surface an altered channel may have two principal conditions that can be corrected. The channel may conduct fewer ions through (loss-of-function mutations) or too many ions (gain-of-function mutations) compared to a normal channel. Toxins from animal venoms are specialised molecules that are generally oriented toward interactions with ion channels. This is a result of long coevolution between predators and their prey. On the molecular level, toxins activate or inhibit ion channels, so they are ideal molecules for restoring conductance in mutated channels. Another aspect of this long coevolution is that a broad variety of toxins have been fine tuned to recognize the channels of different species, keeping many amino acids substitution among sequences. Many peptide ligands with high selectivity to specific receptor subtypes have been isolated from animal venoms, some of which are absolutely non-toxic to humans and mammalians. It is expected that molecules that are selective to each known receptor can be found in animal venoms, but the pool of toxins currently does not override all receptors described as being involved in channelopathies. Modern investigating methods have enhanced the search process for selective ligands. One prominent method is a site-directed mutagenesis of existing toxins to change the selectivity or/and affinity to the selected receptor, which has shown positive results. This article is part of the Special Issue entitled 'Channelopathies.'
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Housley DM, Housley GD, Liddell MJ, Jennings EA. Scorpion toxin peptide action at the ion channel subunit level. Neuropharmacology 2016; 127:46-78. [PMID: 27729239 DOI: 10.1016/j.neuropharm.2016.10.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 09/06/2016] [Accepted: 10/06/2016] [Indexed: 12/19/2022]
Abstract
This review categorizes functionally validated actions of defined scorpion toxin (SCTX) neuropeptides across ion channel subclasses, highlighting key trends in this rapidly evolving field. Scorpion envenomation is a common event in many tropical and subtropical countries, with neuropharmacological actions, particularly autonomic nervous system modulation, causing significant mortality. The primary active agents within scorpion venoms are a diverse group of small neuropeptides that elicit specific potent actions across a wide range of ion channel classes. The identification and functional characterisation of these SCTX peptides has tremendous potential for development of novel pharmaceuticals that advance knowledge of ion channels and establish lead compounds for treatment of excitable tissue disorders. This review delineates the unique specificities of 320 individual SCTX peptides that collectively act on 41 ion channel subclasses. Thus the SCTX research field has significant translational implications for pathophysiology spanning neurotransmission, neurohumoral signalling, sensori-motor systems and excitation-contraction coupling. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- David M Housley
- College of Medicine and Dentistry, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia; Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Gary D Housley
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia
| | - Michael J Liddell
- Centre for Tropical Environmental and Sustainability Science and College of Science & Engineering, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia
| | - Ernest A Jennings
- College of Medicine and Dentistry, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia; Centre for Biodiscovery and Molecular Development of Therapeutics, James Cook University, Queensland 4878, Australia; Australian Institute of Tropical Health and Medicine, James Cook University, Cairns Campus, QLD, Australia
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Santibáñez-López CE, Francke OF, Ureta C, Possani LD. Scorpions from Mexico: From Species Diversity to Venom Complexity. Toxins (Basel) 2015; 8:E2. [PMID: 26712787 PMCID: PMC4728524 DOI: 10.3390/toxins8010002] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 11/25/2015] [Accepted: 12/09/2015] [Indexed: 12/13/2022] Open
Abstract
Scorpions are among the oldest terrestrial arthropods, which are distributed worldwide, except for Antarctica and some Pacific islands. Scorpion envenomation represents a public health problem in several parts of the world. Mexico harbors the highest diversity of scorpions in the world, including some of the world's medically important scorpion species. The systematics and diversity of Mexican scorpion fauna has not been revised in the past decade; and due to recent and exhaustive collection efforts as part of different ongoing major revisionary systematic projects, our understanding of this diversity has changed compared with previous assessments. Given the presence of several medically important scorpion species, the study of their venom in the country is also important. In the present contribution, the diversity of scorpion species in Mexico is revised and updated based on several new systematic contributions; 281 different species are recorded. Commentaries on recent venomic, ecological and behavioral studies of Mexican scorpions are also provided. A list containing the most important peptides identified from 16 different species is included. A graphical representation of the different types of components found in these venoms is also revised. A map with hotspots showing the current knowledge on scorpion distribution and areas explored in Mexico is also provided.
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Affiliation(s)
- Carlos E Santibáñez-López
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Apartado Postal 510-3, Cuernavaca Morelos 62210, Mexico.
| | - Oscar F Francke
- Colección Nacional de Arácnidos, Instituto de Biología, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, Copilco, Coyoacán A.P. 70-233, Distrito Federal 04510, Mexico.
| | - Carolina Ureta
- Laboratorio de Genética Molecular, Desarrollo y Evolución de Plantas, Departamento de Ecología Funcional, Instituto de Ecología, Universidad Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria, Distrito Federal 04510, Mexico.
| | - Lourival D Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Apartado Postal 510-3, Cuernavaca Morelos 62210, Mexico.
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Chhabra S, Chang SC, Nguyen HM, Huq R, Tanner MR, Londono LM, Estrada R, Dhawan V, Chauhan S, Upadhyay SK, Gindin M, Hotez PJ, Valenzuela JG, Mohanty B, Swarbrick JD, Wulff H, Iadonato SP, Gutman GA, Beeton C, Pennington MW, Norton RS, Chandy KG. Kv1.3 channel-blocking immunomodulatory peptides from parasitic worms: implications for autoimmune diseases. FASEB J 2014; 28:3952-64. [PMID: 24891519 DOI: 10.1096/fj.14-251967] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 05/12/2014] [Indexed: 12/26/2022]
Abstract
The voltage-gated potassium (Kv) 1.3 channel is widely regarded as a therapeutic target for immunomodulation in autoimmune diseases. ShK-186, a selective inhibitor of Kv1.3 channels, ameliorates autoimmune diseases in rodent models, and human phase 1 trials of this agent in healthy volunteers have been completed. In this study, we identified and characterized a large family of Stichodactyla helianthus toxin (ShK)-related peptides in parasitic worms. Based on phylogenetic analysis, 2 worm peptides were selected for study: AcK1, a 51-residue peptide expressed in the anterior secretory glands of the dog-infecting hookworm Ancylostoma caninum and the human-infecting hookworm Ancylostoma ceylanicum, and BmK1, the C-terminal domain of a metalloprotease from the filarial worm Brugia malayi. These peptides in solution adopt helical structures closely resembling that of ShK. At doses in the nanomolar-micromolar range, they block native Kv1.3 in human T cells and cloned Kv1.3 stably expressed in L929 mouse fibroblasts. They preferentially suppress the proliferation of rat CCR7(-) effector memory T cells without affecting naive and central memory subsets and inhibit the delayed-type hypersensitivity (DTH) response caused by skin-homing effector memory T cells in rats. Further, they suppress IFNγ production by human T lymphocytes. ShK-related peptides in parasitic worms may contribute to the potential beneficial effects of probiotic parasitic worm therapy in human autoimmune diseases.
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Affiliation(s)
- Sandeep Chhabra
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Shih Chieh Chang
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Hai M Nguyen
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA; Department of Pharmacology, University of California, Davis, California, USA
| | - Redwan Huq
- Department of Molecular Physiology and Biophysics, Graduate Program in Molecular Physiology and Biophysics, and
| | - Mark R Tanner
- Department of Molecular Physiology and Biophysics, Interdepartmental Graduate Program in Translational Biology and Molecular Medicine, and
| | | | | | - Vikas Dhawan
- Peptides International, Louisville, Kentucky, USA
| | | | - Sanjeev K Upadhyay
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Mariel Gindin
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University, Washington D.C., USA; and Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Peter J Hotez
- Sabin Vaccine Institute and Texas Children's Hospital Center for Vaccine Development, National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Jesus G Valenzuela
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Biswaranjan Mohanty
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - James D Swarbrick
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California, USA
| | | | - George A Gutman
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | | | | | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia;
| | - K George Chandy
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA;
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Mille BG, Peigneur S, Diego-García E, Predel R, Tytgat J. Partial transcriptomic profiling of toxins from the venom gland of the scorpion Parabuthus stridulus. Toxicon 2014; 83:75-83. [DOI: 10.1016/j.toxicon.2014.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 02/05/2014] [Accepted: 03/04/2014] [Indexed: 01/02/2023]
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Luna-Ramírez K, Bartok A, Restano-Cassulini R, Quintero-Hernández V, Coronas FIV, Christensen J, Wright CE, Panyi G, Possani LD. Structure, Molecular Modeling, and Function of the Novel Potassium Channel Blocker Urotoxin Isolated from the Venom of the Australian Scorpion Urodacus yaschenkoi. Mol Pharmacol 2014; 86:28-41. [DOI: 10.1124/mol.113.090183] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Berkut AA, Usmanova DR, Peigneur S, Oparin PB, Mineev KS, Odintsova TI, Tytgat J, Arseniev AS, Grishin EV, Vassilevski AA. Structural similarity between defense peptide from wheat and scorpion neurotoxin permits rational functional design. J Biol Chem 2014; 289:14331-40. [PMID: 24671422 DOI: 10.1074/jbc.m113.530477] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
In this study, we present the spatial structure of the wheat antimicrobial peptide (AMP) Tk-AMP-X2 studied using NMR spectroscopy. This peptide was found to adopt a disulfide-stabilized α-helical hairpin fold and therefore belongs to the α-hairpinin family of plant defense peptides. Based on Tk-AMP-X2 structural similarity to cone snail and scorpion potassium channel blockers, a mutant molecule, Tk-hefu, was engineered by incorporating the functionally important residues from κ-hefutoxin 1 onto the Tk-AMP-X2 scaffold. The designed peptide contained the so-called essential dyad of amino acid residues significant for channel-blocking activity. Electrophysiological studies showed that although the parent peptide Tk-AMP-X2 did not present any activity against potassium channels, Tk-hefu blocked Kv1.3 channels with similar potency (IC50 ∼ 35 μm) to κ-hefutoxin 1 (IC50 ∼ 40 μm). We conclude that α-hairpinins are attractive in their simplicity as structural templates, which may be used for functional engineering and drug design.
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Affiliation(s)
- Antonina A Berkut
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia, Moscow Institute of Physics and Technology (State University), Moscow 117303, Russia
| | - Dinara R Usmanova
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia, Moscow Institute of Physics and Technology (State University), Moscow 117303, Russia
| | - Steve Peigneur
- Laboratory of Toxicology and Pharmacology, University of Leuven, Leuven 3000, Belgium, and
| | - Peter B Oparin
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Konstantin S Mineev
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Tatyana I Odintsova
- N. I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
| | - Jan Tytgat
- Laboratory of Toxicology and Pharmacology, University of Leuven, Leuven 3000, Belgium, and
| | - Alexander S Arseniev
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Eugene V Grishin
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Alexander A Vassilevski
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia,
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Ait-Lounis A, Laraba-Djebari F. TNF-α involvement in insulin resistance induced by experimental scorpion envenomation. PLoS Negl Trop Dis 2012; 6:e1740. [PMID: 22816003 PMCID: PMC3398957 DOI: 10.1371/journal.pntd.0001740] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 06/05/2012] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Scorpion venom induces systemic inflammation characterized by an increase in cytokine release and chemokine production. There have been few experimental studies assessing the effects of scorpion venom on adipose tissue function in vivo. METHODOLOGY/PRINCIPAL FINDINGS To study the adipose tissue inflammation (ATI) induced by Androctonus australis hector (Aah) venom and to assess possible mechanisms of ATI, mice (n = 6, aged 1 month) were injected with Aah (0.45 mg/kg), toxic fraction of Aah (FTox-G50; 0.2 mg/kg) or saline solution (control). Inflammatory responses were evaluated by ELISA and cell sorting analyses in adipose tissue 45 minutes and 24 hours after injection. Quantitative real-time PCR was used to assess the regulation of genes implicated in glucose uptake. The titers of selected inflammatory cytokines (IL-1β, IL-6 and TNF-α) were also determined in sera and in insulin target tissues. The serum concentration of IL-1β rose 45 minutes after envenomation and returned to basal level after 24 hours. The pathophysiological effects of the venom after 24 hours mainly involved M1-proinflammatory macrophage infiltration in adipose tissue combined with high titers of IL-1β, IL-6 and TNF-α. Indeed, TNF-α was strongly induced in both adipose tissue and skeletal muscle. We studied the effects of Aah venom on genes implicated in insulin-stimulated glucose uptake. Insulin induced a significant increase in the expression of the mRNAs for hexokinase 2 and phosphatidylinositol 3-kinase in both skeletal muscle and adipose tissue in control mice; this upregulation was completely abolished after 24 hours in mice envenomed with Aah or FTox-G50. CONCLUSIONS/SIGNIFICANCE Our findings suggest that Aah venom induces insulin resistance by mechanisms involving TNF-α-dependent Map4k4 kinase activation in the adipose tissue.
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Affiliation(s)
- Aouatef Ait-Lounis
- Laboratory of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene (USTHB), Algiers, Algeria
- Laboratory of Research and Development on Venoms, Pasteur Institute of Algeria, Algiers, Algeria
| | - Fatima Laraba-Djebari
- Laboratory of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Sciences and Technology Houari Boumediene (USTHB), Algiers, Algeria
- Laboratory of Research and Development on Venoms, Pasteur Institute of Algeria, Algiers, Algeria
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Chen ZY, Zeng DY, Hu YT, He YW, Pan N, Ding JP, Cao ZJ, Liu ML, Li WX, Yi H, Jiang L, Wu YL. Structural and functional diversity of acidic scorpion potassium channel toxins. PLoS One 2012; 7:e35154. [PMID: 22511981 PMCID: PMC3325286 DOI: 10.1371/journal.pone.0035154] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 03/09/2012] [Indexed: 12/19/2022] Open
Abstract
Background Although the basic scorpion K+ channel toxins (KTxs) are well-known pharmacological tools and potential drug candidates, characterization the acidic KTxs still has the great significance for their potential selectivity towards different K+ channel subtypes. Unfortunately, research on the acidic KTxs has been ignored for several years and progressed slowly. Principal Findings Here, we describe the identification of nine new acidic KTxs by cDNA cloning and bioinformatic analyses. Seven of these toxins belong to three new α-KTx subfamilies (α-KTx28, α-KTx29, and α-KTx30), and two are new members of the known κ-KTx2 subfamily. ImKTx104 containing three disulfide bridges, the first member of the α-KTx28 subfamily, has a low sequence homology with other known KTxs, and its NMR structure suggests ImKTx104 adopts a modified cystine-stabilized α-helix-loop-β-sheet (CS-α/β) fold motif that has no apparent α-helixs and β-sheets, but still stabilized by three disulfide bridges. These newly described acidic KTxs exhibit differential pharmacological effects on potassium channels. Acidic scorpion toxin ImKTx104 was the first peptide inhibitor found to affect KCNQ1 channel, which is insensitive to the basic KTxs and is strongly associated with human cardiac abnormalities. ImKTx104 selectively inhibited KCNQ1 channel with a Kd of 11.69 µM, but was less effective against the basic KTxs-sensitive potassium channels. In addition to the ImKTx104 toxin, HeTx204 peptide, containing a cystine-stabilized α-helix-loop-helix (CS-α/α) fold scaffold motif, blocked both Kv1.3 and KCNQ1 channels. StKTx23 toxin, with a cystine-stabilized α-helix-loop-β-sheet (CS-α/β) fold motif, could inhibit Kv1.3 channel, but not the KCNQ1 channel. Conclusions/Significance These findings characterize the structural and functional diversity of acidic KTxs, and could accelerate the development and clinical use of acidic KTxs as pharmacological tools and potential drugs.
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Affiliation(s)
- Zong-Yun Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Dan-Yun Zeng
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, People's Republic of China
| | - You-Tian Hu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Ya-Wen He
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Na Pan
- Key Laboratory of Molecular Biophysics, Ministry of Education,College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Jiu-Ping Ding
- Key Laboratory of Molecular Biophysics, Ministry of Education,College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Zhi-Jian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Mai-Li Liu
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, People's Republic of China
| | - Wen-Xin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Hong Yi
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
- * E-mail: (LJ); (HY); (YW)
| | - Ling Jiang
- Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, People's Republic of China
- * E-mail: (LJ); (HY); (YW)
| | - Ying-Liang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
- * E-mail: (LJ); (HY); (YW)
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Zhu L, Gao B, Luo L, Zhu S. Two dyad-free Shaker-type K⁺ channel blockers from scorpion venom. Toxicon 2012; 59:402-7. [PMID: 22239942 DOI: 10.1016/j.toxicon.2011.11.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 11/14/2011] [Accepted: 11/15/2011] [Indexed: 11/27/2022]
Abstract
Most of scorpion toxins affecting voltage-gated K⁺ channels (KTxs) contain a functional dyad composed of a lysine and an aromatic amino acid separated by a suitable distance. By means of two-electrode voltage clamp technique, we describe functional characterization of two Mesobuthus martensii KTxs (BmP02 and BmP03) without the dyad. These two toxins differ by only one single residue at site 16 (K16N) but they display differential affinities on insect and mammalian Shaker-type K⁺ channels expressed in Xenopus oocytes. At 1 μM concentration, BmP02 and BmP03 inhibited currents of rK(v)1.1, rK(v)1.2, rK(v)1.3, and Shaker IR, but lacked detectable activity on rK(v)1.4. The half-inhibitory concentrations (IC₅₀) of BmP02 for rK(v)1.1, rK(v)1.2, rK(v)1.3 and Shaker IR channels are 1.95 μM, 4.40 μM, 7 nM and 20.44 μM, respectively. For BmP03, the corresponding IC₅₀ values for these channels are 5.48 μM, 530 nM, 85.4 nM, and 4.64 μM, respectively. Affinity variation (more than 10-fold) between BmP02 and BmP03 on rK(v)1.3 indicates functional importance of a cationic side chain at site 16. A pH-dependent experiment and a double mutant cycle analysis suggest that the residue K16 resides on the channel-facing surface of the toxin and within 5 Å of rK(v)1.3 position 401. These two toxins block rK(v)1.3 in a weak voltage-dependent manner and both slightly shift the current activation curve to positive potentials. Our work is thus crucial to further understanding structure-function relationship of KTxs without a functional dyad.
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Affiliation(s)
- Limei Zhu
- Group of Animal Innate Immunity, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China
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García-Gómez BI, Olamendi-Portugal TC, Paniagua J, van der Walt J, Dyason K, Possani LD. Heterologous expression of a gene that codes for Pg8, a scorpion toxin of Parabuthus granulatus, capable of generating protecting antibodies in mice. Toxicon 2009; 53:770-8. [DOI: 10.1016/j.toxicon.2009.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 01/22/2009] [Accepted: 02/02/2009] [Indexed: 10/21/2022]
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Wang S, Huang L, Wicher D, Chi C, Xu C. Structure-function relationship of bifunctional scorpion toxin BmBKTx1. Acta Biochim Biophys Sin (Shanghai) 2008; 40:955-63. [PMID: 18989577 DOI: 10.1111/j.1745-7270.2008.00479.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
As the first identified scorpion toxin active on both big conductance Ca2+-activated K+ channels (BK) and small conductance Ca2+-activated K+ channels (SK), BmBKTx1 has been proposed to have two separate functional faces for two targets. To investigate this hypothesis, two double mutants, K21A-Y30A and R9A-K11A, together with wild-type toxin were expressed in Escherichia coli. The recombinant toxins were tested on cockroach BK and rat SK2 channel for functional assay. Mutant K21A-Y30A had a dramatic loss of function on BK but retained its function on SK. Mutant R9A-K11A did not lose function on BK or SK. These data support the two functional-face hypothesis and indicate that the BK face is on the C-terminal beta-sheet.
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Affiliation(s)
- Suming Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, China
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14
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Zarrabi M, Naderi-Manesh H. The investigation of interactions of kappa-Hefutoxin1 with the voltage-gated potassium channels: a computational simulation. Proteins 2008; 71:1441-9. [PMID: 18076029 DOI: 10.1002/prot.21833] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Kappa-Hefutoxin1 is a K(+) channel-blocking toxin from the scorpion Heterometrus fluvipes. It is a 22-residue protein that adapts a novel fold of two parallel helices linked by two disulfide bridges without beta-sheets. Recognition of interactions of kappa-Hefutoxin1 with the voltage-gated potassium channels, Kv1.1, Kv1.2, and Kv1.3, was studied by 3D-Dock software package. All structures of kappa-Hefutoxin1 were considered during the simulations, which indicated that even small changes in the structure of kappa-Hefutoxin1 considerably affected both the recognition and the binding between kappa-Hefutoxin1 and the Kv1 channels. kappa-Hefutoxin1 is located around the extracellular part of the Kv1 channels, making contacts with its helices. Lys 19, Tyr 5, Arg 6, Trp 9, or Arg 10 in the toxin and residues Asp 402, His 404, Thr 407,Gly 401, and Asp 386 in each subunit of the Kv potassium channel are the key residues for the toxin-channel recognition. Moreover, the simulation result demonstrates that the hydrophobic interactions are important in interaction of negatively charged toxins with potassium channels. The results of our docking/molecular dynamics simulations indicate that our 3D model structure of the kappa-Hefutoxin1-complex is both reasonable and acceptable and could be helpful for smarter drug design and the blocking agents of Kv1 channels.
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Affiliation(s)
- M Zarrabi
- Department of Biophysics, Faculty of Science, Tarbiat Modares University, Tehran, Iran
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Hu P, Sun L, Zhu ZQ, Hou XW, Wang S, Yu SS, Wang HL, Zhang P, Wang M, Niu LW, Teng MK, Ruan DY. Crystal structure of Natratoxin, a novel snake secreted phospholipaseA2 neurotoxin from Naja atra venom inhibiting A-type K+ currents. Proteins 2008; 72:673-83. [PMID: 18247353 DOI: 10.1002/prot.21964] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Snake secreted phospholipasesA2 (sPLA2s) are widely used as pharmacological tools to investigate their role in diverse pathophysiological processes. Some members of snake venom sPLA2s have been found to block voltage-activated K(+) channels (K(v) channels). However, most studies involved in their effects on ion channels were indirectly performed on motor nerve terminals while few studies were directly done on native neurons. Here, a novel snake sPLA2 peptide neurotoxin, Natratoxin, composed of 119 amino acid residues and purified from Naja atra venom was reported. It was characterized using whole-cell patch-clamp in acutely dissociated rat dorsal root ganglion (DRG) neurons. It was found to effectively inhibit A-type K(+) currents and cause alterations of channel gating characters, such as the shifts of steady-state activation and inactivation curves to hyperpolarization direction and changes of V(1/2) and slope factor. Therefore, Natratoxin was suggested to be a gating modifier of K(v) channel. In addition, this inhibitory effect was found to be independent of its enzymatic activity. These results suggested that the toxin enacted its inhibitory effect by binding to K(v) channel. To further elucidate the structural basis for this electrophysiological phenomenon, we determined the crystal structure of Natratoxin at 2.2 A resolution by molecular replacement method and refined to an R-factor of 0.190. The observed overall fold has a different structural organization from other K(+) channel inhibitors in animal toxins. Compared with other K(v) channel inhibitors, a similar putative functional surface in its C-terminal was revealed to contribute to protein-protein interaction in such a blocking effect. Our results demonstrated that the spatial distribution of key amino acid residues matters most in the recognition of this toxin towards its channel target rather than its type of fold.
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Affiliation(s)
- Pu Hu
- Department of Neurobiology and Biophysics, School of Life Sciences, University of Science and Technology of China, HeFei, Anhui, 230027, People's Republic of China
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17
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Abstract
The I-conotoxin superfamily (I-Ctx) is known to have four disulfide bonds with the cysteine arrangement C-C-CC-CC-C-C, and the members inhibit or modify ion channels of nerve cells. Recently, Olivera and co-workers (FEBS J. 2005; 272: 4178-4188) have suggested that the previously described I-Ctx should now be divided into two different gene superfamilies, namely, I1 and I2, in view of their having two different types of signal peptides and exhibiting distinct functions. We have revisited the 28 entries presently grouped as I-Ctx in UniProt Swiss-Prot knowledgebase, and on the basis of in silico analysis have divided them into I1 and I2 superfamilies. The sequence analysis has provided a framework for in silico annotation enabling us to carry out computer-based functional characterization of the UniProtKB/TrEMBL entry Q59AA4 from Conus miles and to predict it as a member of the I2 superfamily. Furthermore, we have predicted the mature toxin of this entry and have proposed that it may be an inhibitor of voltage-gated potassium channels.
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Affiliation(s)
- Sukanta Mondal
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
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Mouhat S, De Waard M, Sabatier JM. Contribution of the functional dyad of animal toxins acting on voltage-gated Kv1-type channels. J Pept Sci 2005; 11:65-8. [PMID: 15635666 DOI: 10.1002/psc.630] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The 'functional dyad', a well-defined pair of amino acid residues (basic and hydrophobic residues), is a key molecular determinant present in most animal toxins acting on voltage-gated Kv1 channels. It is increasingly used as a working concept to explain how toxins are able to recognize and block their specific ion channel targets. However, other crucial toxin determinants are emerging and the actual role of this 'functional dyad' ought to be clarified, which is the object of the present mini-review.
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Affiliation(s)
- Stephanie Mouhat
- Laboratoire Cellpep S.A., 13-15 Rue Ledru-Rollin, 13015 Marseille, France
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Soudani N, Gharbi-Chihi J, Srairi-Abid N, Yazidi CME, Planells R, Margotat A, Torresani J, El Ayeb M. Isolation and molecular characterization of LVP1 lipolysis activating peptide from scorpion Buthus occitanus tunetanus. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1747:47-56. [PMID: 15680238 DOI: 10.1016/j.bbapap.2004.09.020] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Accepted: 09/28/2004] [Indexed: 10/26/2022]
Abstract
LVP1, a novel protein inducing lipolytic response in adipose cells, was purified from scorpion Buthus occitanus tunetanus venom. It represented 1% of crude venom proteins, with pHi approximately 6 and molecular mass of 16170 Da. In contrast to well-characterized scorpion toxins, reduction and alkylation of LVP1 revealed an heterodimeric structure. Isolated alpha and beta chains of LVP1 have a respective molecular mass of 8877 and 8807 Da as determined by mass spectrometry. The N-terminal and some internal peptide sequences of LVP1alpha and beta were determined by Edman degradation. The full amino acid sequences of both chains were deduced from nucleotide sequences of the corresponding cDNAs prepared based on peptide sequences and the 3' and 5' RACE methodologies. LVP1alpha and beta cDNAs encode a signal peptide of 22 residues and a mature peptide of 69 and 73 residues, respectively. Each mature peptide contains seven cysteines, which are compatible with an interchain disulfide bridge. The cDNA deduced protein structures share a high similarity with those of some Na+ channel scorpion toxins. LVP1 was not toxic to mice after intracerebro-ventricular injection. LVP1 stimulated lipolysis on freshly dissociated rat adipocytes in a dose-dependent manner with EC50 of approximately 1+0.5 microg/ml. LVP1 subunits did not display any lipolytic activity. As previously described for venom, beta adrenergic receptor (beta AR) antagonists interfere with LVP1 activity. Furthermore, it is shown that LVP1 competes with [3H]-CGP 12177 (beta1/beta2 antagonist) for binding to adipocyte plasma membrane with an IC50 of about 10(-7) M. These results demonstrate the existence of a new type of scorpion venom nontoxic peptides that are structurally related to Na+ channel toxins but can exert a distinct biological activity on adipocyte lipolysis through a beta-type adrenoreceptor pathway.
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Affiliation(s)
- Nejla Soudani
- Laboratoire des venins et toxines, Institut Pasteur de Tunis, 13 Place Pasteur, BP 74-1002 Tunis, Tunisie, Tunisia
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Abstract
Much of our knowledge on K+-channels was elucidated using specific peptide ligands isolated from a number of venomous organisms. Recently, this field received a strong support and increased interest due to the solution of the three-dimensional structure of a couple of K+-channels. At the same time, several new subfamilies of specific toxins for K+-channels were isolated from scorpion venoms, enhancing the availability and diversity of such useful molecular tools. It opened new lines of research for the better understanding of K+-channel biophysics and pharmacology. In this review, we listed 120 amino acid sequences of peptides isolated from scorpion venoms. They were demonstrated or assumed to be specific for K+-channels. These sequences were aligned and used to generate a rooted phylogenetic tree. The evolutionary tree indicates that several clusters of divergent peptides show preference for specific subtypes of channels. The three-dimensional structures of representative examples of these peptides were drawn and analysed concerning the molecular fitness of their interactions with the channel targets. Four different interacting modes were identified to exist between scorpion toxins and the various subtypes of K+-channels.
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Affiliation(s)
- Ricardo C Rodríguez de la Vega
- Department of Molecular Medicine and Bioprocesses, Institute of Biotechnology, National Autonomous University of Mexico, Avenida Universidad, 2001, Apartado Postal 510-3, Cuernavaca 62210, Mexico
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