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Ding L, Chen J, Hao J, Zhang J, Huang X, Hu F, Wu Z, Liu Y, Li W, Cao Z, Wu Y, Li J, Li S, Liu H, Wu W, Chen Z. Discovery of three toxin peptides with Kv1.3 channel and IL-2 cytokine-inhibiting activities from Non-Buthidae scorpions, Chaerilus tricostatus and Chaerilus tryznai. Peptides 2017; 91:13-19. [PMID: 28300672 DOI: 10.1016/j.peptides.2017.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 03/06/2017] [Accepted: 03/08/2017] [Indexed: 12/29/2022]
Abstract
Non-Buthidae venomous scorpions are huge natural sources of toxin peptides; however, only a few studies have been done to understand their toxin peptides. Herein, we describe three new potential immunomodulating toxin peptides, Ctri18, Ctry68 and Ctry2908, from two non-Buthidae scorpions, Chaerilus tricostatus and Chaerilus tryznai. Sequence alignment analyses showed that Ctri18, Ctry68 and Ctry2908 are three new members of the scorpion toxin α-KTx15 subfamily. Electrophysiological experiments showed that Ctri18, Ctry68 and Ctry2908 blocked the Kv1.3 channel at micromole to nanomole levels, but had weak effects on potassium channel KCNQ1 and sodium channel Nav1.4, which indicated that Ctri18, Ctry68 and Ctry2908 might have specific inhibiting effects on the Kv1.3 channel. ELISA experiments showed that Ctri18, Ctry68 and Ctry2908 inhibited IL-2 cytokine secretions of activated T lymphocyte in human PBMCs. Excitingly, consistent with the good Kv1.3 channel inhibitory activity, Ctry2908 inhibited cytokine IL-2 secretion in nanomole level, which indicated that Ctry2908 might be a new lead drug template toward Kv1.3 channels. Together, these studies discovered three new toxin peptides, Ctri18, Ctry68 and Ctry2908, with Kv1.3 channel and IL-2 cytokine-inhibiting activities from two scorpions, C. tricostatus and C. tryznai, and highlighted that non-Buthidae venomous scorpions are new natural toxin peptide sources.
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Affiliation(s)
- Li Ding
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Department of Clinical Laboratory, Dongfeng Hospital, Hubei University of Medicine, Hubei, China
| | - Jing Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Jinbo Hao
- Department of Clinical Laboratory, Shiyan Occupational Disease Hospital, Hubei, China
| | - Jiahui Zhang
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Xuejun Huang
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Fangfang Hu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Zheng Wu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Yaru Liu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Hubei, China
| | - Jian Li
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Shan Li
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Department of Clinical Laboratory, Dongfeng Hospital, Hubei University of Medicine, Hubei, China
| | - Hongyan Liu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Department of Clinical Laboratory, Dongfeng Hospital, Hubei University of Medicine, Hubei, China
| | - Wenlong Wu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Department of Clinical Laboratory, Dongfeng Hospital, Hubei University of Medicine, Hubei, China
| | - Zongyun Chen
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China.
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Mlayah-Bellalouna S, Dufour M, Mabrouk K, Mejdoub H, Carlier E, Othman H, Belghazi M, Tarbe M, Goaillard JM, Gigmes D, Seagar M, El Ayeb M, Debanne D, Srairi-Abid N. AaTX1, from Androctonus australis scorpion venom: purification, synthesis and characterization in dopaminergic neurons. Toxicon 2014; 92:14-23. [PMID: 25240295 DOI: 10.1016/j.toxicon.2014.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/21/2014] [Accepted: 09/09/2014] [Indexed: 10/24/2022]
Abstract
We have purified the AaTX1 peptide from the Androctonus australis (Aa) scorpion venom, previously cloned and sequenced by Legros and collaborators in a venom gland cDNA library from Aa scorpion. AaTX1 belongs to the α-Ktx15 scorpion toxins family (αKTx15-4). Characterized members of this family share high sequence similarity and were found to block preferentially IA-type voltage-dependent K(+) currents in rat cerebellum granular cells in an irreversible way. In the current work, we studied the effects of native AaTX1 (nAaTX1) using whole-cell patch-clamp recordings of IA current in substantia nigra pars compacta dopaminergic neurons. At 250 nM, AaTX1 induces 90% decrease in IA current amplitude. Its activity was found to be comparable to that of rAmmTX3 (αKTx15-3), which differs by only one conserved (R/K) amino acid in the 19th position suggesting that the difference between R19 and K19 in AaTX1 and AmmTX3, respectively, may not be critical for the toxins' effects. Molecular docking of both toxins with Kv4.3 channel is in agreement with experimental data and suggests the implication of the functional dyade K27-Y36 in toxin-channel interactions. Since AaTX1 is not highly abundant in Aa venom, it was synthesized as well as AmmTX3. Synthetic peptides, native AaTX1 and rAmmTX3 peptides showed qualitatively the same pharmacological activity. Overall, these data identify a new biologically active toxin that belongs to a family of peptides active on Kv4.3 channel.
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Affiliation(s)
- Saoussen Mlayah-Bellalouna
- Institut Pasteur de Tunis, Laboratoire des Venins et biomolécules thérapeutiques LR11IPT08, Tunis 1002, Tunisia
| | - Martial Dufour
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse (UNIS), Faculté de Médecine - Secteur Nord, Aix Marseille Université, 51, Bd Pierre Dramard, 13015 Marseille, France
| | - Kamel Mabrouk
- Aix Marseille Université, Institut de Chimie Radicalaire ICR, UMR 7273, Equipe CROPS, Site St Jérôme, Avenue Escadrille Normandie Niémen, Case 542, 13397 Marseille Cedex 20, France
| | - Hafedh Mejdoub
- USCR séquenceur de protéines, faculté des sciences de Sfax, Route de Soukra, Km 3.5, BP 1171, 3000 Sfax, Tunisia
| | - Edmond Carlier
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse (UNIS), Faculté de Médecine - Secteur Nord, Aix Marseille Université, 51, Bd Pierre Dramard, 13015 Marseille, France
| | - Houcemeddine Othman
- Institut Pasteur de Tunis, Laboratoire des Venins et biomolécules thérapeutiques LR11IPT08, Tunis 1002, Tunisia
| | - Maya Belghazi
- CRN2M UMR 7286, Plate Forme de Recherche en Neurosciences - CAPM, Faculté de Médecine-secteur Nord Aix Marseille Université, 51 bd Pierre Dramard, 13015 Marseille, France
| | - Marion Tarbe
- Aix Marseille Université, Institut de Chimie Radicalaire ICR, UMR 7273, Equipe CROPS, Site St Jérôme, Avenue Escadrille Normandie Niémen, Case 542, 13397 Marseille Cedex 20, France
| | - Jean Marc Goaillard
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse (UNIS), Faculté de Médecine - Secteur Nord, Aix Marseille Université, 51, Bd Pierre Dramard, 13015 Marseille, France
| | - Didier Gigmes
- Aix Marseille Université, Institut de Chimie Radicalaire ICR, UMR 7273, Equipe CROPS, Site St Jérôme, Avenue Escadrille Normandie Niémen, Case 542, 13397 Marseille Cedex 20, France
| | - Michael Seagar
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse (UNIS), Faculté de Médecine - Secteur Nord, Aix Marseille Université, 51, Bd Pierre Dramard, 13015 Marseille, France
| | - Mohamed El Ayeb
- Institut Pasteur de Tunis, Laboratoire des Venins et biomolécules thérapeutiques LR11IPT08, Tunis 1002, Tunisia
| | - Dominique Debanne
- INSERM UMR_S 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse (UNIS), Faculté de Médecine - Secteur Nord, Aix Marseille Université, 51, Bd Pierre Dramard, 13015 Marseille, France
| | - Najet Srairi-Abid
- Institut Pasteur de Tunis, Laboratoire des Venins et biomolécules thérapeutiques LR11IPT08, Tunis 1002, Tunisia.
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Interaction of the scorpion toxin discrepin with Kv4.3 channels and A-type K+ channels in cerebellum granular cells. Biochim Biophys Acta Gen Subj 2014; 1840:2744-51. [DOI: 10.1016/j.bbagen.2014.05.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 05/01/2014] [Accepted: 05/12/2014] [Indexed: 12/13/2022]
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Recombinant expression and functional characterization of martentoxin: a selective inhibitor for BK channel (α + β4). Toxins (Basel) 2014; 6:1419-33. [PMID: 24759175 PMCID: PMC4014743 DOI: 10.3390/toxins6041419] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 03/27/2014] [Accepted: 04/01/2014] [Indexed: 12/22/2022] Open
Abstract
Martentoxin (MarTX), a 37-residue peptide purified from the venom of East-Asian scorpion (Buthus martensi Karsch), was capable of blocking large-conductance Ca2+-activated K+ (BK) channels. Here, we report an effective expression and purification approach for this toxin. The cDNA encoding martentoxin was expressed by the prokaryotic expression system pGEX-4T-3 which was added an enterokinase cleavage site by PCR. The fusion protein (GST-rMarTX) was digested by enterokinase to release hetero-expressed toxin and further purified via reverse-phase HPLC. The molecular weight of the hetero-expressed rMarTX was 4059.06 Da, which is identical to that of the natural peptide isolated from scorpion venom. Functional characterization through whole-cell patch clamp showed that rMarTX selectively and potently inhibited the currents of neuronal BK channels (α + β4) (IC50 = 186 nM), partly inhibited mKv1.3, but hardly having any significant effect on hKv4.2 and hKv3.1a even at 10 μM. Successful expression of martentoxin lays basis for further studies of structure-function relationship underlying martentoxin or other potassium-channel specific blockers.
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Kv1.3 potassium channel-blocking toxin Ctri9577, novel gating modifier of Kv4.3 potassium channel from the scorpion toxin family. Biochem Biophys Res Commun 2014; 444:406-10. [DOI: 10.1016/j.bbrc.2014.01.094] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 01/19/2014] [Indexed: 01/11/2023]
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Maffie JK, Dvoretskova E, Bougis PE, Martin-Eauclaire MF, Rudy B. Dipeptidyl-peptidase-like-proteins confer high sensitivity to the scorpion toxin AmmTX3 to Kv4-mediated A-type K+ channels. J Physiol 2013; 591:2419-27. [PMID: 23440961 DOI: 10.1113/jphysiol.2012.248831] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
K+ channels containing Kv4.2 and Kv4.3 pore-forming subunits mediate most of the subthreshold-operating somatodendritic A-type K+ current in CNS neurons. These channels are believed to be important in regulating the frequency of repetitive firing, the backpropagation of action potential into dendrites, and dendritic integration and plasticity. Moreover, they have been implicated in several diseases from pain to epilepsy and autism spectrum disorders. The lack of toxins that specifically and efficiently block these channels has hampered studies aimed at confirming their functional role and their involvement in disease. AmmTX3 and other related members of the α-KTX15 family of scorpion toxins have been shown to block the A-type K+ current in cultured neurons, but their specificity has been questioned because the toxins do not efficiently block the currents mediated by Kv4.2 or Kv4.3 subunits expressed in heterologous cells. Here we show that the high-affinity blockade of Kv4.2 and Kv4.3 channels by AmmTX3 depends on the presence of the auxiliary subunits DPP6 and DPP10. These proteins are thought to be components of the Kv4 channel complex in neurons and to be important for channel expression in dendrites. These studies validate the use of AmmTX3 as a blocker of the Kv4-mediated A-type K+ current in neurons.
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Affiliation(s)
- Jon K Maffie
- Smilow Neuroscience Program, NYU School of Medicine, 522 First Avenue, New York, NY 10016, USA
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Xie S, Feng J, Yu C, Li Z, Wu Y, Cao Z, Li W, He X, Xiang M, Han S. Identification of a new specific Kv1.3 channel blocker, Ctri9577, from the scorpion Chaerilus tricostatus. Peptides 2012; 36:94-9. [PMID: 22580271 DOI: 10.1016/j.peptides.2012.04.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 04/26/2012] [Accepted: 04/26/2012] [Indexed: 01/04/2023]
Abstract
Scorpion toxins are valuable resources for discovering new ion channel modulators and drug candidates. Potassium channel Kv1.3 is an important pharmacological target of T cell-mediated autoimmune diseases, which are encouraging the screening and design of the specific peptide blockers for Kv1.3 channel. Ctri9577, the first neurotoxin gene of Chaerilidae family was cloned from the venom of the scorpion Chaerilus tricostatus through the constructing its cDNA library. The sequence analysis showed that the mature peptide of Ctri9577 contained 39 amino acid residues including six conserved cysteines, whose low sequence similarity indicated that it was a new member of α-KTx15 subfamily. By using expression and purification technology, the recombinant peptide was obtained. Subsequently, the electrophysiological experiments indicated that the Ctri9577 peptide selectively inhibited Kv1.3 channel current with an IC(50) of 0.49±0.45 nM without effectively blocking potassium channels Kv1.1, Kv1.2, hERG and SK3. All these findings not only enrich the knowledge of toxins from the Chaerilidae family, but also present a novel potential drug candidate targeting Kv1.3 channels for the therapy of autoimmune diseases.
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Affiliation(s)
- Shujun Xie
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, People's Republic of China
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Truchet B, Manrique C, Sreng L, Chaillan FA, Roman FS, Mourre C. Kv4 potassium channels modulate hippocampal EPSP-spike potentiation and spatial memory in rats. Learn Mem 2012; 19:282-93. [PMID: 22700470 DOI: 10.1101/lm.025411.111] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Kv4 channels regulate the backpropagation of action potentials (b-AP) and have been implicated in the modulation of long-term potentiation (LTP). Here we showed that blockade of Kv4 channels by the scorpion toxin AmmTX3 impaired reference memory in a radial maze task. In vivo, AmmTX3 intracerebroventricular (i.c.v.) infusion increased and stabilized the EPSP-spike (E-S) component of LTP in the dentate gyrus (DG), with no effect on basal transmission or short-term plasticity. This increase in E-S potentiation duration could result from the combination of an increase in excitability of DG granular cells with a reduction of GABAergic inhibition, leading to a strong reduction of input specificity. Radioactive in situ hybridization (ISH) was used to evaluate the amounts of Kv4.2 and Kv4.3 mRNA in brain structures at different stages of a spatial learning task in naive, pseudoconditioned, and conditioned rats. Significant differences in Kv4.2 and Kv4.3 mRNA levels were observed between conditioned and pseudoconditioned rats. Kv4.2 and Kv4.3 mRNA levels were transiently up-regulated in the striatum, nucleus accumbens, retrosplenial, and cingulate cortices during early stages of learning, suggesting an involvement in the switch from egocentric to allocentric strategies. Spatial learning performance was positively correlated with the levels of Kv4.2 and Kv4.3 mRNAs in several of these brain structures. Altogether our findings suggest that Kv4 channels could increase the signal-to-noise ratio during information acquisition, thereby allowing a better encoding of the memory trace.
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Affiliation(s)
- Bruno Truchet
- Laboratory of Neuroscience and Cognition-LNC-UMR 7291, Centre National de la Recherche Scientifique-Aix-Marseille Université, Centre Saint-Charles, 13331 Marseille, France
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Towards therapeutic applications of arthropod venom k(+)-channel blockers in CNS neurologic diseases involving memory acquisition and storage. J Toxicol 2012; 2012:756358. [PMID: 22701481 PMCID: PMC3373146 DOI: 10.1155/2012/756358] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 02/08/2012] [Indexed: 12/31/2022] Open
Abstract
Potassium channels are the most heterogeneous and widely distributed group of ion channels and play important functions in all cells, in both normal and pathological mechanisms, including learning and memory processes. Being fundamental for many diverse physiological processes, K+-channels are recognized as potential therapeutic targets in the treatment of several Central Nervous System (CNS) diseases, such as multiple sclerosis, Parkinson's and Alzheimer's diseases, schizophrenia, HIV-1-associated dementia, and epilepsy. Blockers of these channels are therefore potential candidates for the symptomatic treatment of these neuropathies, through their neurological effects. Venomous animals have evolved a wide set of toxins for prey capture and defense. These compounds, mainly peptides, act on various pharmacological targets, making them an innumerable source of ligands for answering experimental paradigms, as well as for therapeutic application. This paper provides an overview of CNS K+-channels involved in memory acquisition and storage and aims at evaluating the use of highly selective K+-channel blockers derived from arthropod venoms as potential therapeutic agents for CNS diseases involving learning and memory mechanisms.
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Ca²⁺/cAMP-sensitive covariation of I(A) and I(H) voltage dependences tunes rebound firing in dopaminergic neurons. J Neurosci 2012; 32:2166-81. [PMID: 22323729 DOI: 10.1523/jneurosci.5297-11.2012] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The level of expression of ion channels has been demonstrated to vary over a threefold to fourfold range from neuron to neuron, although the expression of distinct channels may be strongly correlated in the same neurons. We demonstrate that variability and covariation also apply to the biophysical properties of ion channels. We show that, in rat substantia nigra pars compacta dopaminergic neurons, the voltage dependences of the A-type (I(A)) and H-type (I(H)) currents exhibit a high degree of cell-to-cell variability, although they are strongly correlated in these cells. Our data also demonstrate that this cell-to-cell covariability of voltage dependences is sensitive to cytosolic cAMP and calcium levels. Finally, using dynamic clamp, we demonstrate that covarying I(A) and I(H) voltage dependences increases the dynamic range of rebound firing while covarying their amplitudes has a homeostatic effect on rebound firing. We propose that the covariation of voltage dependences of ion channels represents a flexible and energy-efficient way of tuning firing in neurons.
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Abdel-Mottaleb Y, Corzo G, Martin-Eauclaire MF, Satake H, Céard B, Peigneur S, Nambaru P, Bougis PE, Possani LD, Tytgat J. A common "hot spot" confers hERG blockade activity to alpha-scorpion toxins affecting K+ channels. Biochem Pharmacol 2008; 76:805-15. [PMID: 18687312 DOI: 10.1016/j.bcp.2008.07.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 07/02/2008] [Accepted: 07/02/2008] [Indexed: 02/01/2023]
Abstract
While alpha-KTx peptides are generally known for their modulation of the Shaker-type and the Ca(2+)-activated potassium channels, gamma-KTxs are associated with hERG channels modulation. An exception to the rule is BmTx3 which belongs to subfamily alpha-KTx15 and can block hERG channels. To explain the peculiar behavior of BmTx3, a tentative "hot spot" formed of 2 basic residues (R18 and K19) was suggested but never further studied [Huys I, et al. BmTx3, a scorpion toxin with two putative functional faces separately active on A-type K(+) and HERG currents. Biochem J 2004;378:745-52]. In this work, we investigated if the "hot spot" is a commonality in subfamily alpha-KTx15 by testing the effect of (AmmTx3, Aa1, discrepin). Furthermore, single mutations altering the "hot spot" in discrepin, have introduced for the very first time a hERG blocking activity to a previously non-active alpha-KTx. Additionally, we could extend our results to other alpha-KTx subfamily members belonging to alpha-KTx1, 4 and 6, therefore, the "hot spot" represents a common pharmacophore serving as a predictive tool for yet to be discovered alpha-KTxs.
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Affiliation(s)
- Yousra Abdel-Mottaleb
- Laboratory of Toxicology, University of Leuven, O&N 2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium
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A positive charge at the N-terminal segment of Discrepin increases the blocking effect of K+ channels responsible for the IA currents in cerebellum granular cells. Biochim Biophys Acta Gen Subj 2008; 1780:750-5. [PMID: 18280256 DOI: 10.1016/j.bbagen.2008.01.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 01/15/2008] [Accepted: 01/17/2008] [Indexed: 11/21/2022]
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Zeng XC, Luo F, Li WX. Molecular dissection of venom from Chinese scorpion Mesobuthus martensii: identification and characterization of four novel disulfide-bridged venom peptides. Peptides 2006; 27:1745-54. [PMID: 16513212 DOI: 10.1016/j.peptides.2006.01.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2005] [Revised: 01/21/2006] [Accepted: 01/23/2006] [Indexed: 11/28/2022]
Abstract
Scorpion venom is composed of a large repertoire of biologically active polypeptides. However, most of these peptides remain to be identified and characterized. In this paper, we report the identification and characterization of four novel disulfide-bridged venom peptides (named BmKBTx, BmKITx, BmKKx1 and BmKKx2, respectively) from the Chinese scorpion, Mesobuthus martensii (also named Buthus martensii Karsch). BmKBTx is composed of 58 amino acid residues and cross-linked by three disulfide bridges. The sequence of BmKBTx shows some similarities to that of the toxin, birtoxin, and its analogs. It is likely that BmKBTx is a beta-toxin active on Na+ channels, which is toxic to either insects or mammals. BmKITx is composed of 71 amino acid residues with four disulfide bridges. It is the longest venom peptide identified from M. martensii so far. BmKITx shows little sequence identity with scorpion alpha-toxins toxic to insects. It is likely that BmKITx is a new type of Na+ -channel specific toxin active on both insects and mammals. BmKKx1 contains 38 amino acid residues cross-linked by three disulfide bridges and shows 84% sequence identity with BmTx3, an inhibitor of A-type K+ channel and HERG currents. BmKKx1 has been classified as alpha-KTx-15.8. BmKKx2 is composed of 36 residues and stabilized by three disulfide bridges. BmKKx2 is a new member of the gamma-K+ -channel toxin subfamily (classified as gamma-KTx 2.2). The venoms of scorpions thus continue to provide novel toxins with potential novel actions on targets.
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Affiliation(s)
- Xian-Chun Zeng
- State Key Laboratory of Virology, Department of Biotechnology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
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D'Suze G, Batista CVF, Frau A, Murgia AR, Zamudio FZ, Sevcik C, Possani LD, Prestipino G. Discrepin, a new peptide of the sub-family α-ktx15, isolated from the scorpion Tityus discrepans irreversibly blocks K+-channels (IA currents) of cerebellum granular cells. Arch Biochem Biophys 2004; 430:256-63. [PMID: 15369825 DOI: 10.1016/j.abb.2004.07.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 07/12/2004] [Indexed: 11/29/2022]
Abstract
A new peptide was purified from the venom of the Venezuelan scorpion Tityus discrepans, by high-performance liquid chromatography and its amino acid sequence was completed by Edman degradation and mass spectrometry analysis. It contains 38 amino acid residues with a molecular weight of 4177.7 atomic mass units, tightly folded by three disulfide bridges, and has a pyroglutamic acid at the N-terminal region. This peptide, named Discrepin, was shown to block preferentially the IA currents of the voltage-dependent K+ -channel of rat cerebellum granular cells in culture. The K+ -currents are inhibited in an apparently irreversible manner, whose 50% inhibitory effect is reached with a 190 nM toxin concentration. The systematic nomenclature proposed for this toxin is alpha-KTx15.6.
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Affiliation(s)
- Gina D'Suze
- Laboratory of Cellular Neuropharmacology, Biochemistry and Biophysics Center, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A, Venezuela
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