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Santhosh KN, Pavana D, Shruthi BR, Thippeswamy NB. Protein profile of scorpion venom from Hottentotta rugiscutis and its immunogenic potential in inducing long term memory response. Toxicon 2022; 205:71-78. [PMID: 34826434 DOI: 10.1016/j.toxicon.2021.11.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 10/27/2021] [Accepted: 11/20/2021] [Indexed: 11/24/2022]
Abstract
The scorpions of the Buthidae family exhibit diverse toxins with proven pharmacological activities and yet underexplored. The Hottentotta rugiscutis is a commonly found south-Indian buthid scorpion, whose venom proteomic profile is unknown. In this study, the venom was biochemically and immunologically characterized by SDS-PAGE, MALDI-TOF MS, Western blot and ELISA. The regional and seasonal variation in the venom composition from the same species was also assessed at the molecular mass level. The venom was further studied in albino mice to understand its impact on various blood parameters. The venom has varied MW proteins from 6 to 275 kDa, four of them were found to be major immunodominant proteins. The mass spectra have revealed that some proteins are predominantly present in the venom of 3-4.5 kDa or 6.5-8.0 kDa, which could be the K+ or Na+ channel blockers respectively whose ratio varied by season. The obtained venom-mass spectra could also be used as H. rugiscutis specific finger-print in identifying the region-specific species. The venom was found to elicit a stress-induced innate immune response in mice, giving rise to a strong Th2 mediated humoral immune response. Overall, this study has provided a glimpse of the venom composition and its immunogenicity.
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Affiliation(s)
- Kambaiah Nagaraj Santhosh
- Department of Postgraduate Studies and Research in Microbiology, Jnana Sahyadri Campus, Kuvempu University, Shivamogga, Karnataka, India.
| | - Dattatreya Pavana
- Department of Postgraduate Studies and Research in Microbiology, Jnana Sahyadri Campus, Kuvempu University, Shivamogga, Karnataka, India.
| | - Balakrishna Rao Shruthi
- Department of Postgraduate Studies and Research in Microbiology, Jnana Sahyadri Campus, Kuvempu University, Shivamogga, Karnataka, India.
| | - Nayaka Boramuthi Thippeswamy
- Department of Postgraduate Studies and Research in Microbiology, Jnana Sahyadri Campus, Kuvempu University, Shivamogga, Karnataka, India.
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Das B, Saviola AJ, Mukherjee AK. Biochemical and Proteomic Characterization, and Pharmacological Insights of Indian Red Scorpion Venom Toxins. Front Pharmacol 2021; 12:710680. [PMID: 34650430 PMCID: PMC8505525 DOI: 10.3389/fphar.2021.710680] [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: 05/17/2021] [Accepted: 08/16/2021] [Indexed: 12/16/2022] Open
Abstract
The Indian red scorpion (Mesobuthus tamulus) is one of the world's deadliest scorpions, with stings representing a life-threatening medical emergency. This species is distributed throughout the Indian sub-continent, including eastern Pakistan, eastern Nepal, and Sri Lanka. In India, Indian red scorpions are broadly distributed in western Maharashtra, Saurashtra, Kerala, Andhra Pradesh, Tamil Nadu, and Karnataka; however, fatal envenomations have been recorded primarily in the Konkan region of Maharashtra. The Indian red scorpion venom proteome comprises 110 proteins belonging to 13 venom protein families. The significant pharmacological activity is predominantly caused by the low molecular mass non-enzymatic Na+ and K+ ion channel toxins. Other minor toxins comprise 15.6% of the total venom proteome. Indian red scorpion stings induce the release of catecholamine, which leads to pathophysiological abnormalities in the victim. A strong correlation has been observed between venom proteome composition and local (swelling, redness, heat, and regional lymph node involvement) and systemic (tachycardia, mydriasis, hyperglycemia, hypertension, toxic myocarditis, cardiac failure, and pulmonary edema) manifestations. Immediate administration of antivenom is the preferred treatment for Indian red scorpion stings. However, scorpion-specific antivenoms have exhibited poor immunorecognition and neutralization of the low molecular mass toxins. The proteomic analysis also suggests that Indian red scorpion venom is a rich source of pharmacologically active molecules that may be envisaged as drug prototypes. The following review summarizes the progress made towards understanding the venom proteome of the Indian red scorpion and addresses the current understanding of the pathophysiology associated with its sting.
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Affiliation(s)
- Bhabana Das
- Department of Molecular Biology and Biotechnology, School of Sciences, Tezpur University, Tezpur, India
| | - Anthony J. Saviola
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Ashis K. Mukherjee
- Department of Molecular Biology and Biotechnology, School of Sciences, Tezpur University, Tezpur, India
- Institute of Advanced Study in Science and Technology, Guwahati, India
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Butt SA, Tahir HM, Ali S, Tariq M, Hassan A, Summer M, Raza C, Khan SY. Evaluation of anti-scorpion ( Hottentota tamulus) venom potential of native plants extracts using mice model. TOXIN REV 2021. [DOI: 10.1080/15569543.2021.1933533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Samima Asad Butt
- Applied Entomology and Toxicology Laboratory, Department of Zoology, Government College University Lahore, Lahore, Pakistan
| | - Hafiz Muhammad Tahir
- Applied Entomology and Toxicology Laboratory, Department of Zoology, Government College University Lahore, Lahore, Pakistan
| | - Shaukat Ali
- Applied Entomology and Toxicology Laboratory, Department of Zoology, Government College University Lahore, Lahore, Pakistan
| | - Muniba Tariq
- Applied Entomology and Toxicology Laboratory, Department of Zoology, Government College University Lahore, Lahore, Pakistan
| | - Ali Hassan
- Applied Entomology and Toxicology Laboratory, Department of Zoology, Government College University Lahore, Lahore, Pakistan
| | - Muhammad Summer
- Applied Entomology and Toxicology Laboratory, Department of Zoology, Government College University Lahore, Lahore, Pakistan
| | - Chand Raza
- Applied Entomology and Toxicology Laboratory, Department of Zoology, Government College University Lahore, Lahore, Pakistan
| | - Shafaat Yar Khan
- Department of Zoology, University of Sargodha, Sargodha, Pakistan
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Ward MJ, Ellsworth SA, Nystrom GS. A global accounting of medically significant scorpions: Epidemiology, major toxins, and comparative resources in harmless counterparts. Toxicon 2018; 151:137-155. [DOI: 10.1016/j.toxicon.2018.07.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/25/2018] [Accepted: 07/05/2018] [Indexed: 01/18/2023]
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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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Gao B, Peigneur S, Dalziel J, Tytgat J, Zhu S. Molecular divergence of two orthologous scorpion toxins affecting potassium channels. Comp Biochem Physiol A Mol Integr Physiol 2011; 159:313-21. [PMID: 21466856 DOI: 10.1016/j.cbpa.2011.03.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/25/2011] [Accepted: 03/28/2011] [Indexed: 11/26/2022]
Abstract
Alpha-KTxs are a diverse group of scorpion short-chain peptide toxins that affect animal potassium channels. We report the biochemical purification, gene cloning, and functional characterization of a new α-KTx named MeuTx3B, from venom of the scorpion Mesobuthus eupeus. MeuTx3B is an orthologue of BmTx3B/Martentoxin (α-KTx16 subfamily) from Mesobuthus martensii that differs by three amino acid substitutions. We found that despite their orthologous relationship, MeuTx3B and BmTx3B exhibit different post-transcriptional processing patterns due to nucleotide mutations in their untranslated regions (UTRs). Our results show that MeuTx3B also differs functionally from BmTx3B in that it lacks inhibitory activity on large conductance calcium-activated potassium channels (BK), implicating the amino acids of difference in conferring the inhibitory activity of BmTx3B. Furthermore, we show that MeuTx3B (2μM) partially inhibits human voltage-gated potassium channel Kv1.3. By using codon-substitution models, we detected signals of positive selection that could drive adaptive evolution of MeuTx3B and related toxins in the functional region associated with pharmacological diversification of toxins in the α-KTx 1 and 16 subfamilies.
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Affiliation(s)
- Bin Gao
- Group of Animal Innate Immunity, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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Kanoo S, Mandal MB, Alex AB, Deshpande SB. Cardiac dysrhythmia produced by Mesobuthus tamulus venom involves NO-dependent G-Cyclase signaling pathway. Naunyn Schmiedebergs Arch Pharmacol 2008; 379:525-32. [PMID: 19037630 DOI: 10.1007/s00210-008-0375-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2008] [Accepted: 11/06/2008] [Indexed: 11/29/2022]
Abstract
Role of G-protein coupled pathways in modulating the cardiotoxic effects produced by Indian red scorpion (Mesobuthus tamulus) venom were examined. The isometric contractions of spontaneously beating or paced (3.5 Hz) rat right atrial preparations in vitro were recorded. The cumulative concentration (0.01-3.0 microg/ml)-response of venom on spontaneously beating atria exhibited a marked decrease in rate (by 55%) and an increase in force (by 92%) only at a higher concentration (3.0 microg/ml). The venom-induced decrease in rate and increase in force were sensitive to atropine, N-omega-nitro-L-arginine methylester (NO synthase inhibitor) and methylene blue (guanylyl cyclase inhibitor). Further, nifedipine, a Ca(2+) channel antagonist, blocked the force changes but not the rate changes induced by venom. In the paced atrium, on the other hand, a concentration-dependent decrease in force was observed, and at 3 microg/ml, the decrease was 50%. Pretreatment with nifedipine, but not with methylene blue, significantly attenuated the venom-induced force changes in paced atrium. The observations of this study demonstrate that the venom-induced atrial dysrhythmia is mediated through the muscarinic receptor-dependent NO-G-cyclase cell-signaling pathways.
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Affiliation(s)
- Sadhana Kanoo
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221 005, India
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8
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Yin LT, Fu YJ, Xu QL, Yang J, Liu ZL, Liang AH, Fan XJ, Xu CG. Potential biochemical therapy of glioma cancer. Biochem Biophys Res Commun 2007; 362:225-9. [PMID: 17707767 DOI: 10.1016/j.bbrc.2007.07.167] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 07/24/2007] [Indexed: 10/23/2022]
Abstract
Glioma is a highly invasive, rapidly spreading form of brain cancer that is resistant to surgical and medical treatment. The recent progresses made in intracellular and ion channels of glioma cells provide a potential new approach for biochemical therapy of brain tumor. In this paper, we reviewed clinical data on chemotherapy by temozolomide and results from new studies on voltage-gated potassium channels, large-conductance Ca(2+)-activated K(+) channels, volume-activated chloride channels, glioma-specific chloride channel and their modulators. These new findings may represent future directions for brain tumor studies and treatment.
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Affiliation(s)
- Li-Tian Yin
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan 030006, PR China
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Das Gupta S, Debnath A, Saha A, Giri B, Tripathi G, Vedasiromoni JR, Gomes A, Gomes A. Indian black scorpion (Heterometrus bengalensis Koch) venom induced antiproliferative and apoptogenic activity against human leukemic cell lines U937 and K562. Leuk Res 2007; 31:817-25. [PMID: 16876244 DOI: 10.1016/j.leukres.2006.06.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 05/31/2006] [Accepted: 06/06/2006] [Indexed: 11/25/2022]
Abstract
Venoms are rich source of several bioactive compounds that possess therapeutic potentials. The different constituents of scorpion venom can modulate cell proliferation, cell growth and cell cycle. In the present communication, the cytotoxic activity of Indian black scorpion (Heterometrus bengalensis) venom was explored on human leukemic U937 and K562 cells. Scorpion venom induced U937 and K562 cell growth inhibition and the IC(50) value calculated to be 41.5 microg/ml (U937) and 88.3 microg/ml (K562). The scorpion venom showed characteristic features of apoptosis such as membrane blebbing, chromatin condensation and DNA degradation in both the cells as evidenced by confocal, fluorescence, scanning electron microscopy. Scorpion venom (IC(50) dose, 48 h) induced DNA fragmentation as evidenced by comet formation. Flow-cytometric assay revealed a significant amount of apoptotic cells (early and late) due to scorpion venom treatment. The venom induced cell cycle arrest was observed with maximum cell accumulation at sub-G(1) phase. Thus, the Indian scorpion (H. bengalensis) venom possessed antiproliferative, cytotoxic and apoptogenic activity against human leukemic cells.
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Affiliation(s)
- Shubho Das Gupta
- Drug Development Division, Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata 700032, India
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10
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Bingham JP, Bian S, Tan ZY, Takacs Z, Moczydlowski E. Synthesis of a biotin derivative of iberiotoxin: binding interactions with streptavidin and the BK Ca2+-activated K+ channel expressed in a human cell line. Bioconjug Chem 2006; 17:689-99. [PMID: 16704206 PMCID: PMC2505059 DOI: 10.1021/bc060002u] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iberiotoxin (IbTx) is a scorpion venom peptide that inhibits BK Ca2+-activated K+ channels with high affinity and specificity. Automated solid-phase synthesis was used to prepare a biotin-labeled derivative (IbTx-LC-biotin) of IbTx by substitution of Asp19 of the native 37-residue peptide with N--(D-biotin-6-amidocaproate)-L-lysine. Both IbTx-LC-biotin and its complex with streptavidin (StrAv) block single BK channels from rat skeletal muscle with nanomolar affinity, indicating that the biotin-labeled residue, either alone or in complex with StrAv, does not obstruct the toxin binding interaction with the BK channel. IbTx-LC-biotin exhibits high affinity (KD = 26 nM) and a slow dissociation rate (koff = 5.4 x 10(-4) s(-1)) in a macroscopic blocking assay of whole-cell current of the cloned human BK channel. Titration of IbTx-LC-biotin with StrAv monitored by high performance size exclusion chromatography is consistent with a stoichiometry of two binding sites for IbTx-LC-biotin per StrAv tetramer, indicating that steric interference hinders simultaneous binding of two toxin molecules on each of the two biotin-binding faces of StrAv. In combination with fluorescent conjugates of StrAv or anti-biotin antibody, IbTx-LC-biotin was used to image the surface distribution of BK channels on a transfected cell line. Fluorescence microscopy revealed a patch-like surface distribution of BK channel protein. The results support the feasibility of using IbTx-LC-biotin and similar biotin-tagged K+ channel toxins for diverse applications in cellular neurobiology. .
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Affiliation(s)
| | - Shumin Bian
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven CT 06520
| | - Zhi-Yong Tan
- Department of Internal Medicine, University of Iowa, Iowa City IA 52242
| | - Zoltan Takacs
- The Department of Pediatrics; University of Chicago, Chicago, IL 60637
| | - Edward Moczydlowski
- Department of Biology, Clarkson University, Potsdam, NY 13699
- Corresponding Author: Edward Moczydlowski, Department of Biology, Box 5805, Clarkson University, Potsdam, NY 13699-5805; Tel.: 315-268-6641; Fax: 315-268-7118; e-mail:
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11
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Judge SIV, Bever CT. Potassium channel blockers in multiple sclerosis: Neuronal Kv channels and effects of symptomatic treatment. Pharmacol Ther 2006; 111:224-59. [PMID: 16472864 DOI: 10.1016/j.pharmthera.2005.10.006] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Accepted: 10/12/2005] [Indexed: 02/07/2023]
Abstract
Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) characterized by demyelination, with a relative sparing of axons. In MS patients, many neurologic signs and symptoms have been attributed to the underlying conduction deficits. The idea that neurologic function might be improved if conduction could be restored in CNS demyelinated axons led to the testing of potassium (K(+)) channel blockers as a symptomatic treatment. To date, only 2 broad-spectrum K(+) channel blockers, 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP), have been tested in MS patients. Although both 4-AP and 3,4-DAP produce clear neurologic benefits, their use has been limited by toxicity. Here we review the current status of basic science and clinical research related to the therapeutic targeting of voltage-gated K(+) channels (K(v)) in MS. By bringing together 3 distinct but interrelated disciplines, we aim to provide perspective on a vast body of work highlighting the lengthy and ongoing process entailed in translating fundamental K(v) channel knowledge into new clinical treatments for patients with MS and other demyelinating diseases. Covered are (1) K(v) channel nomenclature, structure, function, and pharmacology; (2) classic and current experimental morphology and neurophysiology studies of demyelination and conduction deficits; and (3) a comprehensive overview of clinical trials utilizing 4-AP and 3,4-DAP in MS patients.
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Affiliation(s)
- Susan I V Judge
- MS Center of Excellence-East, Research and Neurology Services, VA Maryland Health Care System, USA.
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Tan PTJ, Srinivasan KN, Seah SH, Koh JLY, Tan TW, Ranganathan S, Brusic V. Accurate prediction of scorpion toxin functional properties from primary structures. J Mol Graph Model 2005; 24:17-24. [PMID: 15950506 DOI: 10.1016/j.jmgm.2005.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Accepted: 01/31/2005] [Indexed: 10/25/2022]
Abstract
Scorpion toxins are common experimental tools for studies of biochemical and pharmacological properties of ion channels. The number of functionally annotated scorpion toxins is steadily growing, but the number of identified toxin sequences is increasing at much faster pace. With an estimated 100,000 different variants, bioinformatic analysis of scorpion toxins is becoming a necessary tool for their systematic functional analysis. Here, we report a bioinformatics-driven system involving scorpion toxin structural classification, functional annotation, database technology, sequence comparison, nearest neighbour analysis, and decision rules which produces highly accurate predictions of scorpion toxin functional properties.
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Affiliation(s)
- Paul T J Tan
- Laboratories for Information Technology, Knowledge Discovery Department, Institute for Infocomm Research, Singapore 119613, Singapore
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Xu CQ, He LL, Brône B, Martin-Eauclaire MF, Van Kerkhove E, Zhou Z, Chi CW. A novel scorpion toxin blocking small conductance Ca2+ activated K+ channel. Toxicon 2004; 43:961-71. [PMID: 15208029 DOI: 10.1016/j.toxicon.2004.01.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2003] [Accepted: 01/08/2004] [Indexed: 11/26/2022]
Abstract
Small conductance calcium activated potassium channels (SK) are crucial in the regulation of cell firing frequency in the nervous system and other tissues. In the present work, a novel SK channel blocker, designated BmSKTx1, was purified from the scorpion Buthus martensi Karsh venom. The sequence of the N-terminal 22 amino acid residues was determined by Edman degradation. Using this sequence information, the full-length cDNA and genomic gene of BmSKTx1 were cloned and sequenced. By these analyses, BmSKTx1 was found to be a peptide composed of 31 amino acid residues with three disulfide bonds. It shared little sequence homology with other known scorpion alpha-KTxs but showed close relationship with SK channel blockers in the phylogenetic tree. According to the previous nomenclature, BmSKTx1 was classified as alpha-KTx14.1. We examined the effects of BmSKTx1 on different ion channels of rat adrenal chromaffin cells (RACC) and locust dorsal unpaired median (DUM) neurons. BmSKTx1 selectively inhibited apamin-sensitive SK currents in RACC with Kd of 0.72 microM and Hill coefficient of 2.2. And it had no effect on Na+, Ca2+, Kv, and BK currents in DUM neuron, indicating that BmSKTx1 was a selective SK toxin.
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Affiliation(s)
- Chen-Qi Xu
- Institute of Neuroscience, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China
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Pedarzani P, D'hoedt D, Doorty KB, Wadsworth JDF, Joseph JS, Jeyaseelan K, Kini RM, Gadre SV, Sapatnekar SM, Stocker M, Strong PN. Tamapin, a venom peptide from the Indian red scorpion (Mesobuthus tamulus) that targets small conductance Ca2+-activated K+ channels and afterhyperpolarization currents in central neurons. J Biol Chem 2002; 277:46101-9. [PMID: 12239213 DOI: 10.1074/jbc.m206465200] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biophysical properties of small conductance Ca(2+)-activated K(+) (SK) channels are well suited to underlie afterhyperpolarizations (AHPs) shaping the firing patterns of a conspicuous number of central and peripheral neurons. We have identified a new scorpion toxin (tamapin) that binds to SK channels with high affinity and inhibits SK channel-mediated currents in pyramidal neurons of the hippocampus as well as in cell lines expressing distinct SK channel subunits. This toxin distinguished between the SK channels underlying the apamin-sensitive I(AHP) and the Ca(2+)-activated K(+) channels mediating the slow I(AHP) (sI(AHP)) in hippocampal neurons. Compared with related scorpion toxins, tamapin displayed a unique, remarkable selectivity for SK2 versus SK1 ( approximately 1750-fold) and SK3 ( approximately 70-fold) channels and is the most potent SK2 channel blocker characterized so far (IC(50) for SK2 channels = 24 pm). Tamapin will facilitate the characterization of the subunit composition of native SK channels and help determine their involvement in electrical and biochemical signaling.
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Affiliation(s)
- Paola Pedarzani
- Department of Physiology, University College London, London WC1E 6BT, United Kingdom
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Dhawan RD, Joseph S, Sethi A, Lala AK. Purification and characterization of a short insect toxin from the venom of the scorpion Buthus tamulus. FEBS Lett 2002; 528:261-6. [PMID: 12297317 DOI: 10.1016/s0014-5793(02)03326-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A short chain peptide has been isolated from the venom of a red scorpion of Indian origin, Buthus tamulus. This peptide was purified using ion exchange and reverse phase chromatography and was characterized by molecular weight determination and amino acid sequence. The primary structure analysis shows that BtITx3 is a short peptide of 35 amino acid residues having a molecular weight of 3796 Da. The toxin shows toxicity towards the Lepidopteran species of insect Helicoverpa armigera causing flaccid paralysis and even death within 24 h. It shows more than 50% homology with the short insectotoxins having four disulfide bridges, which suggests that the toxin belongs to the class of short chain toxins blocking the chloride ion channels. This sequence homology study has also helped to bring out the structure-function relationship between the various short toxins. Homology modeling done by using template structure of a known toxin indicated that this toxin consists of a similar alpha/beta scaffold, as present in other scorpion toxins.
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Affiliation(s)
- Ritu Dhawan Dhawan
- Biomembrane Lab, Department of Chemistry and School of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
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