1
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Cholasseri R, De S. Deciphering the shape selective conformational equilibrium of E- and Z-locked azobenzene-tetraethylammonium ion in regulating photo-switchable K +-ion channel blocking. Phys Chem Chem Phys 2024; 26:19161-19175. [PMID: 38973424 DOI: 10.1039/d4cp01604a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
The search for photo-switchable optopharmacological agents that can block ion channels has been a prevalent area owing to its prime advantages of reversibility and specificity over the traditional blockers. However, the quest for a higher blocking ability shown by a less stable photo-isomer to perfectly suit the requirement of the optopharmacological agents is still ongoing. To date, only a marginal improvement in terms of blocking ability is observed by the less stable E-isomer of para-substituted locked azobenzene with TEA (LAB-TEA) for the K+-ion channel. Thus, rationalization of the limitation for achieving high activity by the E-isomer is rather essential to aid the improvement of the efficiency of photoswitchable blocker drugs. Herein, we report a molecular-level analysis on the mechanism of blocking by E- and Z-LAB-TEA with the bacterial KcsA K+-ion channel using Molecular Dynamics (MD) simulation and Quantum Mechanical (QM) calculations. The positively charged TEA fragment engages in stronger electrostatic interactions, while the neutral LAB fragment engages in weaker dispersive interactions. The binding free energy calculated by Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) for E-LAB-TEA (-22.3 kcal mol-1) shows less thermodynamic preference for binding with K+-ion channels than Z-LAB-TEA (-21.6 kcal mol-1) corroborating the experimental observation. The correlation between the structure and the binding ability of E- and Z-isomers of LAB-TEA indicates that the channel gate is narrow and acts as a bottleneck for the entry of the binder molecule inside the large cavity. Upon irradiation, the Z-isomer converts into a less stable but long and planar E-isomer (ΔE of photoisomerism = 7.0 kcal mol-1, at SA2-CASPT2(6,4)/6-31+G(d)//CASSCF(6,4)/6-31+G(d)), which is structurally more suitable to fit into the narrow channel gate rather than the curved and non-planar Z-LAB-TEA. Thus, a reduction in the ionic current is observed owing to the preferential entry and subsequent blocking by E-LAB-TEA. Discontinuing the irradiation leads to conversion to the Z-isomer, the curved nature of which hinders its spontaneous release outside the cavity, thereby contributing only a small increase in the ionic current.
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Affiliation(s)
- Rinsha Cholasseri
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, National Institute of Technology Calicut, Kozhikode, Kerala, 673 601, India
| | - Susmita De
- Department of Chemistry, University of Calicut, Calicut University P. O, Malappuram, Kerala, 673 635, India.
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2
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Xia Z, He D, Wu Y, Kwok HF, Cao Z. Scorpion venom peptides: Molecular diversity, structural characteristics, and therapeutic use from channelopathies to viral infections and cancers. Pharmacol Res 2023; 197:106978. [PMID: 37923027 DOI: 10.1016/j.phrs.2023.106978] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 10/23/2023] [Accepted: 10/27/2023] [Indexed: 11/07/2023]
Abstract
Animal venom is an important evolutionary innovation in nature. As one of the most representative animal venoms, scorpion venom contains an extremely diverse set of bioactive peptides. Scorpion venom peptides not only are 'poisons' that immobilize, paralyze, kill, or dissolve preys but also become important candidates for drug development and design. Here, the review focuses on the molecular diversity of scorpion venom peptides, their typical structural characteristics, and their multiple therapeutic or pharmaceutical applications in channelopathies, viral infections and cancers. Especially, the group of scorpion toxin TRPTx targeting transient receptor potential (TRP) channels is systematically summarized and worthy of attention because TRP channels play a crucial role in the regulation of homeostasis and the occurrence of diseases in human. We also further establish the potential relationship between the molecular characteristics and functional applications of scorpion venom peptides to provide a research basis for modern drug development and clinical utilization of scorpion venom resources.
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Affiliation(s)
- Zhiqiang Xia
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian, China
| | - Dangui He
- State Key Laboratory of Virology, College of Life Sciences, Shenzhen Research Institute, Wuhan University, Wuhan, China; Department of Biomedical Sciences, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macao; Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macao
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Shenzhen Research Institute, Wuhan University, Wuhan, China
| | - Hang Fai Kwok
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macao; Cancer Centre, Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macao; MoE Frontiers Science Center for Precision Oncology, University of Macau, Avenida de Universidade, Taipa, Macao.
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Shenzhen Research Institute, Wuhan University, Wuhan, China; Bio-drug Research Center, Wuhan University, Wuhan, China.
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3
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Kuzmenkov AI, Gigolaev AM, Pinheiro-Junior EL, Peigneur S, Tytgat J, Vassilevski AA. Methionine-isoleucine dichotomy at a key position in scorpion toxins inhibiting voltage-gated potassium channels. Toxicon 2023; 231:107181. [PMID: 37301298 DOI: 10.1016/j.toxicon.2023.107181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/06/2023] [Accepted: 06/06/2023] [Indexed: 06/12/2023]
Abstract
Previous studies have identified some key amino acid residues in scorpion toxins blocking potassium channels. In particular, the most numerous toxins belonging to the α-KTx family and affecting voltage-gated potassium channels (KV) present a conserved K-C-X-N motif in the C-terminal half of their sequence. Here, we show that the X position of this motif is almost always occupied by either methionine or isoleucine. We compare the activity of three pairs of peptides that differ just by this residue on a panel of KV1 channels and find that toxins bearing methionine affect preferentially KV1.1 and 1.6 isoforms. The refined K-C-M/I-N motif stands out as the principal structural element of α-KTx conferring high affinity and selectivity to KV channels.
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Affiliation(s)
- Alexey I Kuzmenkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
| | - Andrei M Gigolaev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | | | - Steve Peigneur
- Toxicology and Pharmacology, KU Leuven, Leuven, 3000, Belgium
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Leuven, 3000, Belgium
| | - Alexander A Vassilevski
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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4
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Zhang X, Zhao Q, Yang F, Lan Z, Li Y, Xiao M, Yu H, Li Z, Zhou Y, Wu Y, Cao Z, Yin S. Mechanisms underlying the inhibition of KV1.3 channel by scorpion toxin ImKTX58. Mol Pharmacol 2022; 102:150-160. [PMID: 35764383 DOI: 10.1124/molpharm.121.000480] [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: 12/22/2021] [Accepted: 06/19/2022] [Indexed: 11/22/2022] Open
Abstract
Voltage-gated KV1.3 channel has been reported to be a drug target for the treatment of autoimmune diseases, and specific inhibitors of Kv1.3 are potential therapeutic drugs for multiple diseases. The scorpions could produce various bioactive peptides which could inhibit KV1.3 channel. Here we identified a new scorpion toxin polypeptide gene ImKTX58 from the venom gland cDNA library of the Chinese scorpion Isometrus maculatus Sequence alignment revealed high similarities between ImKTX58 mature peptide and previously reported KV1.3 channel blockers - LmKTX10 and ImKTX88, suggesting that ImKTX58 peptide might also be a KV1.3 channel blocker. By using electrophysiological recordings, we showed that recombinant ImKTX58 prepared by genetic engineering technologies had a highly selective inhibiting effect on KV1.3 channel. Further alanine scanning mutagenesis and computer simulation identified four amino acid residues in ImKTX58 peptide as key binding sites to KV1.3 channel by forming hydrogen bonds, salt bonds and hydrophobic interactions. Among these four residues, 28th lysine of the ImKTX58 mature peptide was found to be the most critical amino acid residue for blocking KV1.3 channel. Significance Statement In this study, we discovered a scorpion toxin gene ImKTX58 which has not been reported before in Hainan Isometrus maculatus and successfully used prokaryotic expression system to express and purify the polypeptides encoded by this gene. Electrophysiological experiments on ImKTX58 showed that ImKTX58 has a selectively blocking effects on KV1.3 channel over Kv1.1, Kv1.2, Kv1.5, SK2, SK3 and BK channels. These findings provide a theoretical basis for designing highly effective KV1.3 blockers to treat autoimmune and other diseases.
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Affiliation(s)
- Xu Zhang
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
| | - Qianru Zhao
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
| | - Fan Yang
- Department of Virology, College of Life Sciences, Wuhan University, China
| | - Zhen Lan
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
| | - Yi Li
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
| | - Min Xiao
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
| | - Hui Yu
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
| | - Ziyi Li
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
| | - Yongsheng Zhou
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
| | - Yingliang Wu
- Department of Virology, College of Life Sciences, Wuhan University, China
| | - Zhijian Cao
- Department of Virology, College of Life Sciences, Wuhan University, China
| | - Shijin Yin
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central University for Nationalities, China
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sVmKTx, a transcriptome analysis-based synthetic peptide analogue of Vm24, inhibits Kv1.3 channels of human T cells with improved selectivity. Biochem Pharmacol 2022; 199:115023. [PMID: 35358481 DOI: 10.1016/j.bcp.2022.115023] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/22/2022] [Accepted: 03/23/2022] [Indexed: 12/13/2022]
Abstract
Kv1.3 K+ channels play a central role in the regulation of T cell activation and Ca2+ signaling under physiological and pathophysiological conditions. Peptide toxins targeting Kv1.3 have a significant therapeutic potential in the treatment of autoimmune diseases; thus, the discovery of new toxins is highly motivated. Based on the transcriptome analysis of the venom gland of V. mexicanus smithi a novel synthetic peptide, sVmKTx was generated, containing 36 amino acid residues. sVmKTx shows high sequence similarity to Vm24, a previously characterized peptide from the same species, but contains a Glu at position 32 as opposed to Lys32 in Vm24. Vm24 inhibits Kv1.3 with high affinity (Kd = 2.9 pM). However, it has limited selectivity (~1,500-fold) for Kv1.3 over hKv1.2, hKCa3.1, and mKv1.1. sVmKTx displays reduced Kv1.3 affinity (Kd = 770 pM) but increased selectivity for Kv1.3 over hKv1.2 (~9,000-fold) as compared to Vm24, other channels tested in the panel (hKCa3.1, hKv1.1, hKv1.4, hKv1.5, rKv2.1, hKv11.1, hKCa1.1, hNav1.5) were practically insensitive to the toxin at 2.5 μM. Molecular dynamics simulations showed that introduction of a Glu instead of Lys at position 32 led to a decreased structural fluctuation of the N-terminal segment of sVmKTx, which may explain its increased selectivity for Kv1.3. sVmKTx at 100 nM concentration decreased the expression level of the Ca2+ -dependent T cell activation marker, CD40 ligand. The high affinity block of Kv1.3 and increased selectivity over the natural peptide makes sVmKTx a potential candidate for Kv1.3 blockade-mediated treatment of autoimmune diseases.
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6
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Naseem MU, Tajti G, Gaspar A, Szanto TG, Borrego J, Panyi G. Optimization of Pichia pastoris Expression System for High-Level Production of Margatoxin. Front Pharmacol 2021; 12:733610. [PMID: 34658872 PMCID: PMC8511391 DOI: 10.3389/fphar.2021.733610] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/30/2021] [Indexed: 11/16/2022] Open
Abstract
Margatoxin (MgTx) is a high-affinity blocker of voltage-gated potassium (Kv) channels. It inhibits Kv1.1–Kv1.3 ion channels in picomolar concentrations. This toxin is widely used to study physiological function of Kv ion channels in various cell types, including immune cells. Isolation of native MgTx in large quantities from scorpion venom is not affordable. Chemical synthesis and recombinant production in Escherichia coli need in vitro oxidative refolding for proper disulfide bond formation, resulting in a very low yield of peptide production. The Pichia pastoris expression system offers an economical approach to overcome all these limitations and gives a higher yield of correctly refolded recombinant peptides. In this study, improved heterologous expression of recombinant MgTx (rMgTx) in P. pastoris was obtained by using preferential codons, selecting the hyper-resistant clone against Zeocin, and optimizing the culturing conditions. About 36 ± 4 mg/L of >98% pure His-tagged rMgTx (TrMgTx) was produced, which is a threefold higher yield than has been previously reported. Proteolytic digestion of TrMgTx with factor Xa generated untagged rMgTx (UrMgTx). Both TrMgTx and UrMgTx blocked the Kv1.2 and Kv1.3 currents (patch-clamp) (Kd for Kv1.2 were 64 and 14 pM, and for Kv1.3, 86 and 50 pM, respectively) with comparable potency to the native MgTx. The analysis of the binding kinetics showed that TrMgTx had a lower association rate than UrMgTx for both Kv1.2 and Kv1.3. The dissociation rate of both the analogues was the same for Kv1.3. However, in the case of Kv1.2, TrMgTx showed a much higher dissociation rate with full recovery of the block than UrMgTx. Moreover, in a biological functional assay, both peptides significantly downregulated the expression of early activation markers IL2R and CD40L in activated CD4+ TEM lymphocytes whose activation was Kv1.3 dependent. In conclusion, the authors report that the Pichia expression system is a powerful method to produce disulfide-rich peptides, the overexpression of which could be enhanced noticeably through optimization strategies, making it more cost-effective. Since the presence of the His-tag on rMgTx only mildly altered the block equilibrium and binding kinetics, recombinant toxins could be used in ion channel research without removing the tag and could thus reduce the cost and time demand for toxin production.
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Affiliation(s)
- Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gabor Tajti
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Gaspar
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology, Institute of Chemistry, University of Debrecen, Debrecen, Hungary
| | - Tibor G Szanto
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jesús Borrego
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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7
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Tabakmakher VM, Kuzmenkov AI, Gigolaev AM, Pinheiro-Junior EL, Peigneur S, Efremov RG, Tytgat J, Vassilevski AA. Artificial Peptide Ligand of Potassium
Channel KV1.1 with High Selectivity. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021020186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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8
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Cholasseri R, De S. Dual-Site Binding of Quaternary Ammonium Ions as Internal K +-Ion Channel Blockers: Nonclassical (C-H···O) H Bonding vs Dispersive (C-H···H-C) Interaction. J Phys Chem B 2021; 125:86-100. [PMID: 33371683 DOI: 10.1021/acs.jpcb.0c09604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A molecular-level study of the influence of the alkyl chain length of quaternary ammonium ions (QAs) on the blocking action and the mode of binding with the bacterial KcsA K+-ion channel is carried out by molecular dynamics (MD) simulations as well as quantum mechanics/molecular mechanics (QM/MM) methods. The present work unveils distinct modes of binding for different QAs, due to differences in size and hydrophobicity. The QAs bind near the channel gate as well as at the central cavity, leading to a possible dual-site blocking action. Small-sized tetraethylammonium (TEA) and tetrabutylammonium (TBA) ions enter inside the channel cavity in the open state of KcsA but bind strongly in the closed state. TEA binds to the polar hydroxyl group of threonine residues situated at the channel gate via nonclassical H-bonding interaction (C-H···O), while TBA binds to a second binding site, the central cavity, with hydrophobic benzyl and sec-butyl side chains of phenylalanine and isoleucine residues via alkyl-π and hydrophobic interactions (C-H···H-C). On the contrary, large tetrahexylammonium (THA) and tetraoctylammonium (TOA) ions bind the hydrophobic side-chain methyl and isopropyl of alanine and valine at the channel gate both in the open and closed states, thereby restricting the free movement of large QAs toward the center of the cavity. However, the binding to the hydrophobic benzyl and sec-butyl side chains of phenylalanine and isoleucine residues in the closed state is thermodynamically preferable. Also, the binding energy is found to increase with an increase in the alkyl chain length from ethyl (-16.4 kcal/mol) to octyl (-65.5 kcal/mol), due to an almost linear increase in dispersive interaction.
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Affiliation(s)
- Rinsha Cholasseri
- Theoretical and Computational Chemistry Laboratory, Department of Chemistry, National Institute of Technology Calicut, Kozhikode, Kerala 673 601, India
| | - Susmita De
- Department of Applied Chemistry, Cochin University of Science and Technology, Trikakkara, Kochi, Kerala 682 022, India.,Inter University Centre for Nanomaterials and Devices, Cochin University of Science and Technology, Trikakkara, Kochi, Kerala 682 022, India
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9
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Gigolaev AM, Kuzmenkov AI, Peigneur S, Tabakmakher VM, Pinheiro-Junior EL, Chugunov AO, Efremov RG, Tytgat J, Vassilevski AA. Tuning Scorpion Toxin Selectivity: Switching From K V1.1 to K V1.3. Front Pharmacol 2020; 11:1010. [PMID: 32733247 PMCID: PMC7358528 DOI: 10.3389/fphar.2020.01010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/23/2020] [Indexed: 01/04/2023] Open
Abstract
Voltage-gated potassium channels (KVs) perform vital physiological functions and are targets in different disorders ranging from ataxia and arrhythmia to autoimmune diseases. An important issue is the search for and production of selective ligands of these channels. Peptide toxins found in scorpion venom named KTx excel in both potency and selectivity with respect to some potassium channel isoforms, which may present only minute differences in their structure. Despite several decades of research the molecular determinants of KTx selectivity are still poorly understood. Here we analyze MeKTx13-3 (Kalium ID: α-KTx 3.19) from the lesser Asian scorpion Mesobuthus eupeus, a high-affinity KV1.1 blocker (IC50 ~2 nM); it also affects KV1.2 (IC50 ~100 nM), 1.3 (~10 nM) and 1.6 (~60 nM). By constructing computer models of its complex with KV1.1-1.3 channels we identify specific contacts between the toxin and the three isoforms. We then perform mutagenesis to disturb the identified contacts with KV1.1 and 1.2 and produce recombinant MeKTx13-3_AAAR, which differs by four amino acid residues from the parent toxin. As predicted by the modeling, this derivative shows decreased activity on KV1.1 (IC50 ~550 nM) and 1.2 (~200 nM). It also has diminished activity on KV1.6 (~1500 nM) but preserves KV1.3 affinity as measured using the voltage-clamp technique on mammalian channels expressed in Xenopus oocytes. In effect, we convert a selective KV1.1 ligand into a new specific KV1.3 ligand. MeKTx13-3 and its derivatives are attractive tools to study the structure-function relationship in potassium channel blockers.
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Affiliation(s)
- Andrei M Gigolaev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Alexey I Kuzmenkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | | | - Valentin M Tabakmakher
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,School of Biomedicine, Far Eastern Federal University, Vladivostok, Russia
| | | | - Anton O Chugunov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,Department of Applied Mathematics, National Research University Higher School of Economics, Moscow, Russia.,Moscow Institute of Physics and Technology (State University), Dolgoprudny, Russia
| | - Roman G Efremov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,Department of Applied Mathematics, National Research University Higher School of Economics, Moscow, Russia.,Moscow Institute of Physics and Technology (State University), Dolgoprudny, Russia
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Leuven, Belgium
| | - Alexander A Vassilevski
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.,Moscow Institute of Physics and Technology (State University), Dolgoprudny, Russia
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10
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Zhu W, Gao H, Luo X, Ye X, Ding L, Hao J, Shu Z, Li S, Li J, Chen Z. Cloning and identification of a new multifunctional Ascaris-type peptide from the hemolymph of Buthus martensii Karsch. Toxicon 2020; 184:167-174. [PMID: 32565098 DOI: 10.1016/j.toxicon.2020.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 06/10/2020] [Accepted: 06/15/2020] [Indexed: 10/24/2022]
Abstract
Only a few work have been done for peptides from non-venom gland tissues of venomous animals. Here, with the help of the whole body transcriptomic and the hemolymph proteomic data of the Chinese scorpion Buthus martensii Karsch, we identified the first Ascaris-type peptide BmHDP from scorpion hemolymph. The precursor of BmHDP has 80 residues, including a 16 residue signal peptide and a 64 residue mature peptide. The mature peptide has 10 conserved cysteines and adopts a conserved Ascaris-type fold. Using combined inclusion body refolding and biochemical identification strategies, recombinant BmHDP was obtained successfully. Protease inhibitory assays showed that BmHDP inhibited chymotrypsin apparently at a concentration of 8 nM. Patch-clamp experiments showed that BmHDP inhibited the Kv1.3 potassium channel apparently at a concentration of 1000 nM. Coagulation experiment assays showed that BmHDP inhibited intrinsic coagulation pathway apparently at a concentration of 500 nM. To the best of our knowledge, BmHDP is the first Ascaris-type peptide from scorpion hemolymph. Our work highlighted a functional link between scorpion non-venom gland peptides and venom gland toxin peptides, and suggested that scorpion hemolymph might be a new source of bioactive peptides.
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Affiliation(s)
- Wen Zhu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Huanhuan Gao
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Xudong Luo
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Institute of Biomedicine and Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Hubei, China
| | - Xiangdong Ye
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Institute of Biomedicine and Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Hubei, China
| | - Li Ding
- Department of Clinical Laboratory, Dongfeng Hospital, Hubei University of Medicine, Hubei, China; Institute of Biomedicine and Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Hubei, China
| | - Jinbo Hao
- Department of Clinical Laboratory, Shiyan Occupational Disease Hospital, Hubei, China
| | - Zhan Shu
- 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
| | - Jian Li
- Department of Human Parasitology, College of Basic Medical Sciences, 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; Institute of Biomedicine and Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Hubei, China.
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11
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Zheng Q, Na R, Yang L, Yu H, Zhao X, Huang X. The binding process of BmKTX and BmKTX-D33H toward to Kv1.3 channel: a molecular dynamics simulation study. J Biomol Struct Dyn 2020; 39:2788-2797. [PMID: 32329410 DOI: 10.1080/07391102.2020.1760135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The potassium channel Kv1.3 is an important pharmacological target and the Kaliotoxin-type toxins (α-KTX-3 family) are its specific blockers. Here, we study the binding process of two kinds of Kaliotoxin-type toxins:BmKTX and its mutant (BmKTX-D33H) toward to Kv1.3 channel using MD simulation and umbrella sampling simulation, respectively. The calculated binding free energies are -27 kcal/mol and -34 kcal/mol for BmKTX and BmKTX-D33H, respectively, which are consistent with experimental results. The further analysis indicate that the characteristic of electrostatic potential of the α-KTX-3 have important effect on their binding modes with Kv1.3 channel; the residue 33 in BmKTX or BmKTX-D33H plays a key role in determine their binding orientations toward to Kv1.3 channel; when residue 33 (or 34) has negative electrostatic potential, the anti-parallel β-sheet domain of α-KTX-3 toxin peptide will keep away from the filter region of Kv1.3 channel, as BmKTX; when residue 33(or 34) has positive electrostatic potential, the anti-parallel β-sheet domain of α-KTX-3 toxin peptide will interact with the filter region of Kv1.3 channel, as BmKTX-D33H. Above all, electrostatic potential differences on toxin surfaces and correlations motions within the toxins will determine the toxin-potassium channel interaction model. In addition, the hydrogen bond interaction is the pivotal factor for the Kv1.3-Kaliotoxin association. Understanding the binding mechanism of toxin-potassium channel will facilitate the rational development of new toxin analogue.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Qiancheng Zheng
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Risong Na
- College of Plant Protection, Henan Agricultural University, Zhengzhou, P.R China
| | - Lianjuan Yang
- Department of Mycology, Shanghai Dermatology Hospital, Shanghai, China
| | - Hui Yu
- College of Science, Beihua Univesrity, Jilin, China
| | - Xi Zhao
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Xuri Huang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
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Yuan S, Gao B, Zhu S. Molecular Dynamics Simulation Reveals Specific Interaction Sites between Scorpion Toxins and K v1.2 Channel: Implications for Design of Highly Selective Drugs. Toxins (Basel) 2017; 9:toxins9110354. [PMID: 29104247 PMCID: PMC5705969 DOI: 10.3390/toxins9110354] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/15/2017] [Accepted: 10/19/2017] [Indexed: 01/06/2023] Open
Abstract
The Kv1.2 channel plays an important role in the maintenance of resting membrane potential and the regulation of the cellular excitability of neurons, whose silencing or mutations can elicit neuropathic pain or neurological diseases (e.g., epilepsy and ataxia). Scorpion venom contains a variety of peptide toxins targeting the pore region of this channel. Despite a large amount of structural and functional data currently available, their detailed interaction modes are poorly understood. In this work, we choose four Kv1.2-targeted scorpion toxins (Margatoxin, Agitoxin-2, OsK-1, and Mesomartoxin) to construct their complexes with Kv1.2 based on the experimental structure of ChTx-Kv1.2. Molecular dynamics simulation of these complexes lead to the identification of hydrophobic patches, hydrogen-bonds, and salt bridges as three essential forces mediating the interactions between this channel and the toxins, in which four Kv1.2-specific interacting amino acids (D353, Q358, V381, and T383) are identified for the first time. This discovery might help design highly selective Kv1.2-channel inhibitors by altering amino acids of these toxins binding to the four channel residues. Finally, our results provide new evidence in favor of an induced fit model between scorpion toxins and K+ channel interactions.
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Affiliation(s)
- Shouli Yuan
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Bin Gao
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Shunyi Zhu
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
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Shen B, Cao Z, Li W, Sabatier JM, Wu Y. Treating autoimmune disorders with venom-derived peptides. Expert Opin Biol Ther 2017; 17:1065-1075. [DOI: 10.1080/14712598.2017.1346606] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Bingzheng Shen
- State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, China
- Department of Pharmacy, Renmin Hospital, Wuhan University, Wuhan, China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, China
| | | | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, China
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Olamendi-Portugal T, Bartok A, Zamudio-Zuñiga F, Balajthy A, Becerril B, Panyi G, Possani LD. Isolation, chemical and functional characterization of several new K+-channel blocking peptides from the venom of the scorpion Centruroides tecomanus. Toxicon 2016; 115:1-12. [DOI: 10.1016/j.toxicon.2016.02.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 02/04/2016] [Accepted: 02/18/2016] [Indexed: 11/29/2022]
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Scorpion Toxin, BmP01, Induces Pain by Targeting TRPV1 Channel. Toxins (Basel) 2015; 7:3671-87. [PMID: 26389953 PMCID: PMC4591660 DOI: 10.3390/toxins7093671] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/01/2015] [Accepted: 09/07/2015] [Indexed: 01/17/2023] Open
Abstract
The intense pain induced by scorpion sting is a frequent clinical manifestation. To date, there is no established protocol with significant efficacy to alleviate the pain induced by scorpion envenomation. One of the important reasons is that, little information on pain-inducing compound from scorpion venoms is available. Here, a pain-inducing peptide (BmP01) has been identified and characterized from the venoms of scorpion (Mesobuthus martensii). In an animal model, intraplantar injection of BmP01 in mouse hind paw showed significant acute pain in wild type (WT) mice but not in TRPV1 knock-out (TRPV1 KO) mice during 30 min recording. BmP01 evoked currents in WT dorsal root ganglion (DRG) neurons but had no effect on DRG neurons of TRPV1 KO mice. Furthermore, OPEN ACCESS Toxins 2015, 7 3672 BmP01 evoked currents on TRPV1-expressed HEK293T cells, but not on HEK293T cells without TRPV1. These results suggest that (1) BmP01 is one of the pain-inducing agents in scorpion venoms; and (2) BmP01 induces pain by acting on TRPV1. To our knowledge, this is the first report about a scorpion toxin that produces pain by targeting TRPV1. Identification of a pain-inducing compound may facilitate treating pain induced by scorpion envenomation.
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Chen J, Zhang C, Yang W, Cao Z, Li W, Chen Z, Wu Y. SjAPI-2 is the first member of a new neurotoxin family with Ascaris-type fold and KCNQ1 inhibitory activity. Int J Biol Macromol 2015; 79:504-10. [DOI: 10.1016/j.ijbiomac.2015.05.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 05/09/2015] [Accepted: 05/12/2015] [Indexed: 01/12/2023]
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17
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Bartok A, Toth A, Somodi S, Szanto TG, Hajdu P, Panyi G, Varga Z. Margatoxin is a non-selective inhibitor of human Kv1.3 K+ channels. Toxicon 2014; 87:6-16. [PMID: 24878374 DOI: 10.1016/j.toxicon.2014.05.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/07/2014] [Accepted: 05/12/2014] [Indexed: 11/28/2022]
Abstract
Margatoxin (MgTx), an alpha-KTx scorpion toxin, is considered a selective inhibitor of the Kv1.3K + channel. This peptide is widely used in ion channel research; however, a comprehensive study of its selectivity with electrophysiological methods has not been published yet. The lack of selectivity might lead to undesired side effects upon therapeutic application or may lead to incorrect conclusion regarding the role of a particular ion channel in a physiological or pathophysiological response either in vitro or in vivo. Using the patch-clamp technique we characterized the selectivity profile of MgTx using L929 cells expressing mKv1.1 channels, human peripheral lymphocytes expressing Kv1.3 channels and transiently transfected tsA201 cells expressing hKv1.1, hKv1.2, hKv1.3, hKv1.4-IR, hKv1.5, hKv1.6, hKv1.7, rKv2.1, Shaker-IR, hERG, hKCa1.1, hKCa3.1 and hNav1.5 channels. MgTx is indeed a high affinity inhibitor of Kv1.3 (Kd = 11.7 pM) but is not selective, it inhibits the Kv1.2 channel with similar affinity (Kd = 6.4 pM) and Kv1.1 in the nanomolar range (Kd = 4.2 nM). Based on our comprehensive data MgTX has to be considered a non-selective Kv1.3 inhibitor, and thus, experiments aiming at elucidating the significance of Kv1.3 in in vitro or in vivo physiological responses have to be carefully evaluated.
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Affiliation(s)
- Adam Bartok
- Department of Biophysics and Cell Biology, University of Debrecen, Faculty of Medicine, 98 Nagyerdei krt., Debrecen 4032, Hungary.
| | - Agnes Toth
- Department of Biophysics and Cell Biology, University of Debrecen, Faculty of Medicine, 98 Nagyerdei krt., Debrecen 4032, Hungary.
| | - Sandor Somodi
- Division of Metabolic Diseases, Department of Internal Medicine, University of Debrecen, 98 Nagyerdei krt., Debrecen 4032, Hungary.
| | - Tibor G Szanto
- Department of Biophysics and Cell Biology, University of Debrecen, Faculty of Medicine, 98 Nagyerdei krt., Debrecen 4032, Hungary.
| | - Peter Hajdu
- Department of Biophysics and Cell Biology, University of Debrecen, Faculty of Dentistry, 98 Nagyerdei krt., Debrecen 4032, Hungary.
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, University of Debrecen, Faculty of Medicine, 98 Nagyerdei krt., Debrecen 4032, Hungary; MTA-DE Cell Biology and Signaling Research Group, 4032 Debrecen, Egyetem tér 1, Hungary. http://biophys.med.unideb.hu/en/node/311
| | - Zoltan Varga
- Department of Biophysics and Cell Biology, University of Debrecen, Faculty of Medicine, 98 Nagyerdei krt., Debrecen 4032, Hungary.
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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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L’envenimation scorpionique au Maroc : scorpions du genre Androctonus, Buthus et Hottentota. ACTA ACUST UNITED AC 2014; 107:39-47. [DOI: 10.1007/s13149-014-0332-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 12/17/2013] [Indexed: 11/25/2022]
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Anangi R, Koshy S, Huq R, Beeton C, Chuang WJ, King GF. Recombinant expression of margatoxin and agitoxin-2 in Pichia pastoris: an efficient method for production of KV1.3 channel blockers. PLoS One 2012; 7:e52965. [PMID: 23300835 PMCID: PMC3530466 DOI: 10.1371/journal.pone.0052965] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 11/26/2012] [Indexed: 02/03/2023] Open
Abstract
The K(v)1.3 voltage-gated potassium channel regulates membrane potential and calcium signaling in human effector memory T cells that are key mediators of autoimmune diseases such as multiple sclerosis, type 1 diabetes, and rheumatoid arthritis. Thus, subtype-specific K(v)1.3 blockers have potential for treatment of autoimmune diseases. Several K(v)1.3 channel blockers have been characterized from scorpion venom, all of which have an α/β scaffold stabilized by 3-4 intramolecular disulfide bridges. Chemical synthesis is commonly used for producing these disulfide-rich peptides but this approach is time consuming and not cost effective for production of mutants, fusion proteins, fluorescently tagged toxins, or isotopically labelled peptides for NMR studies. Recombinant production of K(v)1.3 blockers in the cytoplasm of E. coli generally necessitates oxidative refolding of the peptides in order to form their native disulfide architecture. An alternative approach that avoids the need for refolding is expression of peptides in the periplasm of E. coli but this often produces low yields. Thus, we developed an efficient Pichia pastoris expression system for production of K(v)1.3 blockers using margatoxin (MgTx) and agitoxin-2 (AgTx2) as prototypic examples. The Pichia system enabled these toxins to be obtained in high yield (12-18 mg/L). NMR experiments revealed that the recombinant toxins adopt their native fold without the need for refolding, and electrophysiological recordings demonstrated that they are almost equipotent with the native toxins in blocking K(V)1.3 (IC(50) values of 201±39 pM and 97 ± 3 pM for recombinant AgTx2 and MgTx, respectively). Furthermore, both recombinant toxins inhibited T-lymphocyte proliferation. A MgTx mutant in which the key pharmacophore residue K28 was mutated to alanine was ineffective at blocking K(V)1.3 and it failed to inhibit T-lymphocyte proliferation. Thus, the approach described here provides an efficient method of producing toxin mutants with a view to engineering K(v)1.3 blockers with therapeutic potential.
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Affiliation(s)
- Raveendra Anangi
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
- * E-mail: (RA); (GK)
| | - Shyny Koshy
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Redwan Huq
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Christine Beeton
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Woei-Jer Chuang
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, National Cheng Kung University College of Medicine, Tainan, Taiwan
| | - Glenn F. King
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, Australia
- * E-mail: (RA); (GK)
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Zhang J, Halm ST, Halm DR. Role of the BK channel (KCa1.1) during activation of electrogenic K+ secretion in guinea pig distal colon. Am J Physiol Gastrointest Liver Physiol 2012; 303:G1322-34. [PMID: 23064759 PMCID: PMC3532550 DOI: 10.1152/ajpgi.00325.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Secretagogues acting at a variety of receptor types activate electrogenic K(+) secretion in guinea pig distal colon, often accompanied by Cl(-) secretion. Distinct blockers of K(Ca)1.1 (BK, Kcnma1), iberiotoxin (IbTx), and paxilline inhibited the negative short-circuit current (I(sc)) associated with K(+) secretion. Mucosal addition of IbTx inhibited epinephrine-activated I(sc) ((epi)I(sc)) and transepithelial conductance ((epi)G(t)) consistent with K(+) secretion occurring via apical membrane K(Ca)1.1. The concentration dependence of IbTx inhibition of (epi)I(sc) yielded an IC(50) of 193 nM, with a maximal inhibition of 51%. Similarly, IbTx inhibited (epi)G(t) with an IC(50) of 220 nM and maximal inhibition of 48%. Mucosally added paxilline (10 μM) inhibited (epi)I(sc) and (epi)G(t) by ∼50%. IbTx and paxilline also inhibited I(sc) activated by mucosal ATP, supporting apical K(Ca)1.1 as a requirement for this K(+) secretagogue. Responses to IbTx and paxilline indicated that a component of K(+) secretion occurred during activation of Cl(-) secretion by prostaglandin-E(2) and cholinergic stimulation. Analysis of K(Ca)1.1α mRNA expression in distal colonic epithelial cells indicated the presence of the ZERO splice variant and three splice variants for the COOH terminus. The presence of the regulatory β-subunits K(Ca)β1 and K(Ca)β4 also was demonstrated. Immunolocalization supported the presence of K(Ca)1.1α in apical and basolateral membranes of surface and crypt cells. Together these results support a cellular mechanism for electrogenic K(+) secretion involving apical membrane K(Ca)1.1 during activation by several secretagogue types, but the observed K(+) secretion likely required the activity of additional K(+) channel types in the apical membrane.
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Affiliation(s)
- Jin Zhang
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine, Dayton, Ohio
| | - Susan T. Halm
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine, Dayton, Ohio
| | - Dan R. Halm
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine, Dayton, Ohio
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Varga Z, Gurrola-Briones G, Papp F, Rodríguez de la Vega RC, Pedraza-Alva G, Tajhya RB, Gaspar R, Cardenas L, Rosenstein Y, Beeton C, Possani LD, Panyi G. Vm24, a natural immunosuppressive peptide, potently and selectively blocks Kv1.3 potassium channels of human T cells. Mol Pharmacol 2012; 82:372-82. [PMID: 22622363 DOI: 10.1124/mol.112.078006] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Blockade of Kv1.3 K(+) channels in T cells is a promising therapeutic approach for the treatment of autoimmune diseases such as multiple sclerosis and type 1 diabetes mellitus. Vm24 (α-KTx 23.1) is a novel 36-residue Kv1.3-specific peptide isolated from the venom of the scorpion Vaejovis mexicanus smithi. Vm24 inhibits Kv1.3 channels of human lymphocytes with high affinity (K(d) = 2.9 pM) and exhibits >1500-fold selectivity over other ion channels assayed. It inhibits the proliferation and Ca(2+) signaling of human T cells in vitro and reduces delayed-type hypersensitivity reactions in rats in vivo. Our results indicate that Vm24 has exceptional pharmacological properties that make it an excellent candidate for treatment of certain autoimmune diseases.
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Affiliation(s)
- Zoltan Varga
- Department of Biophysics and Cell Biology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
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Gurrola GB, Hernández-López RA, Rodríguez de la Vega RC, Varga Z, Batista CVF, Salas-Castillo SP, Panyi G, del Río-Portilla F, Possani LD. Structure, function, and chemical synthesis of Vaejovis mexicanus peptide 24: a novel potent blocker of Kv1.3 potassium channels of human T lymphocytes. Biochemistry 2012; 51:4049-61. [PMID: 22540187 DOI: 10.1021/bi300060n] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Animal venoms are rich sources of ligands for studying ion channels and other pharmacological targets. Proteomic analyses of the soluble venom from the Mexican scorpion Vaejovis mexicanus smithi showed that it contains more than 200 different components. Among them, a 36-residue peptide with a molecular mass of 3864 Da (named Vm24) was shown to be a potent blocker of Kv1.3 of human lymphocytes (K(d) ∼ 3 pM). The three-dimensional solution structure of Vm24 was determined by nuclear magnetic resonance, showing the peptide folds into a distorted cystine-stabilized α/β motif consisting of a single-turn α-helix and a three-stranded antiparallel β-sheet, stabilized by four disulfide bridges. The disulfide pairs are formed between Cys6 and Cys26, Cys12 and Cys31, Cys16 and Cys33, and Cys21 and Cys36. Sequence analyses identified Vm24 as the first example of a new subfamily of α-type K(+) channel blockers (systematic number α-KTx 23.1). Comparison with other Kv1.3 blockers isolated from scorpions suggests a number of structural features that could explain the remarkable affinity and specificity of Vm24 toward Kv1.3 channels of lymphocytes.
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Affiliation(s)
- Georgina B Gurrola
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad, 2001 Cuernavaca, Mor. 62210, Mexico
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24
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Chen PC, Kuyucak S. Developing a comparative docking protocol for the prediction of peptide selectivity profiles: investigation of potassium channel toxins. Toxins (Basel) 2012; 4:110-38. [PMID: 22474570 PMCID: PMC3317111 DOI: 10.3390/toxins4020110] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 01/06/2012] [Accepted: 01/14/2012] [Indexed: 12/28/2022] Open
Abstract
During the development of selective peptides against highly homologous targets, a reliable tool is sought that can predict information on both mechanisms of binding and relative affinities. These tools must first be tested on known profiles before application on novel therapeutic candidates. We therefore present a comparative docking protocol in HADDOCK using critical motifs, and use it to “predict” the various selectivity profiles of several major αKTX scorpion toxin families versus Kv1.1, Kv1.2 and Kv1.3. By correlating results across toxins of similar profiles, a comprehensive set of functional residues can be identified. Reasonable models of channel-toxin interactions can be then drawn that are consistent with known affinity and mutagenesis. Without biological information on the interaction, HADDOCK reproduces mechanisms underlying the universal binding of αKTX-2 toxins, and Kv1.3 selectivity of αKTX-3 toxins. The addition of constraints encouraging the critical lysine insertion confirms these findings, and gives analogous explanations for other families, including models of partial pore-block in αKTX-6. While qualitatively informative, the HADDOCK scoring function is not yet sufficient for accurate affinity-ranking. False minima in low-affinity complexes often resemble true binding in high-affinity complexes, despite steric/conformational penalties apparent from visual inspection. This contamination significantly complicates energetic analysis, although it is usually possible to obtain correct ranking via careful interpretation of binding-well characteristics and elimination of false positives. Aside from adaptations to the broader potassium channel family, we suggest that this strategy of comparative docking can be extended to other channels of interest with known structure, especially in cases where a critical motif exists to improve docking effectiveness.
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Affiliation(s)
- Po-Chia Chen
- School of Physics, Building A28, University of Sydney, NSW 2006, 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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Yi H, Qiu S, Wu Y, Li W, Wang B. Differential molecular information of maurotoxin peptide recognizing IK(Ca) and Kv1.2 channels explored by computational simulation. BMC STRUCTURAL BIOLOGY 2011; 11:3. [PMID: 21262000 PMCID: PMC3041654 DOI: 10.1186/1472-6807-11-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 01/25/2011] [Indexed: 12/19/2022]
Abstract
BACKGROUND Scorpion toxins are invaluable tools for ion channel research and are potential drugs for human channelopathies. However, it is still an open task to determine the molecular basis underlying the diverse interactions between toxin peptides and ion channels. The inhibitory peptide Maurotoxin (MTX) recognized the distantly related IK(Ca) and Kv1.2 channel with approximately the same potency and using the same functional residues, their differential binding mechanism remain elusive. In this study, we applied computational methods to explore the differential binding modes of MTX to Kv1.2 and IK(Ca) channels, which would help to understand the diversity of channel-toxin interactions and accelerate the toxin-based drug design. RESULTS A reasonably stable MTX-IK(Ca) complex was obtained by combining various computational methods and by in-depth comparison with the previous model of the MTX-Kv1.2 complex. Similarly, MTX adopted the β-sheet structure as the interacting surface for binding both channels, with Lys23 occluding the pore. In contrast, the other critical residues Lys27, Lys30, and Tyr32 of MTX adopted distinct interactions when associating with the IK(Ca) channel. In addition, the residues Gln229, Ala230, Ala233, and Thr234 on the IK(Ca) channel turret formed polar and non-polar interactions with MTX, whereas the turret of Kv1.2 was almost not involved in recognizing MTX. In all, the pairs of interacting residues on MTX and the IK(Ca) channel of the bound complex indicated that electrostatic and Van der Waal interactions contributed equally to the formation of a stable MTX-IK(Ca) complex, in contrast to the MTX-Kv1.2 binding that is dominantly mediated by electrostatic forces. CONCLUSIONS Despite sharing similar pharmacological profiles toward both IK(Ca) and Kv1.2 channels, MTX adopted totally diverging modes in the two association processes. All the molecular information unveiled here could not only offer a better understanding about the structural differences between the IK(Ca) and Kv1.2 channels, but also provide novel structural clues that will help in the designing of more selective molecular probes to discriminate between these two channels.
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Affiliation(s)
- Hong Yi
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
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Zhu S, Gao B, Aumelas A, del Carmen Rodríguez M, Lanz-Mendoza H, Peigneur S, Diego-Garcia E, Martin-Eauclaire MF, Tytgat J, Possani LD. MeuTXKβ1, a scorpion venom-derived two-domain potassium channel toxin-like peptide with cytolytic activity. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:872-83. [DOI: 10.1016/j.bbapap.2009.12.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 12/22/2009] [Accepted: 12/23/2009] [Indexed: 11/24/2022]
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Qiu S, Yi H, Liu H, Cao Z, Wu Y, Li W. Molecular Information of Charybdotoxin Blockade in the Large Conductance Calcium-activated Potassium Channel. J Chem Inf Model 2009; 49:1831-8. [DOI: 10.1021/ci900025n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Su Qiu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Hong Yi
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Hui Liu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
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29
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Bingham JP, Chun JB, Ruzicka MR, Li QX, Tan ZY, Kaulin YA, Englebretsen DR, Moczydlowski EG. Synthesis of an iberiotoxin derivative by chemical ligation: a method for improved yields of cysteine-rich scorpion toxin peptides. Peptides 2009; 30:1049-57. [PMID: 19463736 PMCID: PMC2998342 DOI: 10.1016/j.peptides.2009.03.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 03/10/2009] [Accepted: 03/10/2009] [Indexed: 10/21/2022]
Abstract
Automated and manual solid phase peptide synthesis techniques were combined with chemical ligation to produce a 37-residue peptide toxin derivative of iberiotoxin which contained: (i) substitution of Val(16) to Ala, to facilitate kinetic feasibility of native chemical ligation, and; (ii) substitution of Asp(19) to orthogonally protected Cys-4-MeOBzl for chemical conjugate derivatization following peptide folding and oxidation. This peptide ligation approach increased synthetic yields approximately 12-fold compared to standard linear peptide synthesis. In a functional inhibition assay, the ligated scorpion toxin derivative, iberiotoxin V16A/D19-Cys-4-MeOBzl, exhibited 'native-like' affinity (K(d)=1.9 nM) and specificity towards the BK Ca(2+)-activated K(+) Channel (K(Ca)1.1). This was characterized by the rapid association and slow dissociation rates (k(on)=4.59 x 10(5)M(-1)s(-1); k(off)=8.65 x 10(-4) s(-1)) as determined by inhibition of macroscopic whole-cell currents of cloned human K(Ca)1.1 channel. These results illustrate the successful application of peptide chemical ligation to improve yield of cysteine-rich peptide toxins over traditional solid phase peptide synthesis. Native chemical ligation is a promising method for improving production of biologically active disulfide containing peptide toxins, which have diverse applications in studies of ion-channel function.
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Affiliation(s)
- Jon-Paul Bingham
- Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawaii, Honolulu, HI 96822, USA.
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Legros C, Guette C, Martin-Eauclaire MF, Goyffon M, Tortajada J. Affinity capture using chimeric membrane proteins bound to magnetic beads for rapid ligand screening by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:745-755. [PMID: 19204930 DOI: 10.1002/rcm.3939] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The rapid and specific detection of therapeutically important ligands in complex mixtures, that may bind to membrane proteins, remains challenging for many research laboratories and pharmaceutical industries. Through its use in the development of screening assays, mass spectrometry (MS) is currently experiencing a period of tremendous expansion. In the study presented here, we took advantage of the remarkable stability properties of a bacterial membrane protein, the KcsA K+ channel, produced in E. coli and purified as a tetrameric protein in the presence of a detergent. This membrane protein can subserve as a molecular template to display the pore-forming region of human K+ channels, which are considered as targets in the search for inhibitory ligands. The engineered chimeric proteins were linked to metal-bound magnetic beads, for the screening of complex peptide mixtures, such as that of scorpion venoms. The affinity-captured scorpion toxins were eluted prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), and to nano-electrospray ionization tandem mass QqTOF mass spectrometry (MS/MS) analysis. The de novo sequence of the toxins was deduced by combining the MS/MS fragmentation of the reduced form (up to the 33 first residues) and the trypsin digest peptides of the native toxins. This affinity-capture screening assay led to the isolation and characterization of potent and specific ligands of the human K+ channel, Kv1.3. The affinity-capture procedure is fast and reproducible. When linked to magnetic beads, the chimeric membrane protein can be re-used several times without losing any of its selectivity or specificity. This assay also benefits from the fact that it requires minimal amounts of animal venoms or complex mixtures, which can be expensive or difficult to procure.
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Affiliation(s)
- Christian Legros
- Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement (LAMBE), Université d'Evry Val d'Essonne, CNRS UMR 8587, Bd F. Mitterrand, 91025 Evry, France.
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31
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Corzo G, Papp F, Varga Z, Barraza O, Espino-Solis PG, Rodríguez de la Vega RC, Gaspar R, Panyi G, Possani LD. A selective blocker of Kv1.2 and Kv1.3 potassium channels from the venom of the scorpion Centruroides suffusus suffusus. Biochem Pharmacol 2008; 76:1142-54. [DOI: 10.1016/j.bcp.2008.08.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 07/29/2008] [Accepted: 08/04/2008] [Indexed: 11/30/2022]
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32
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Giangiacomo KM, Becker J, Garsky C, Schmalhofer W, Garcia ML, Mullmann TJ. Novel α-KTx Sites in the BK Channel and Comparative Sequence Analysis Reveal Distinguishing Features of the BK and KV Channel Outer Pore. Cell Biochem Biophys 2008; 52:47-58. [DOI: 10.1007/s12013-008-9026-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2008] [Indexed: 01/30/2023]
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33
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Batista CVF, Román-González SA, Salas-Castillo SP, Zamudio FZ, Gómez-Lagunas F, Possani LD. Proteomic analysis of the venom from the scorpion Tityus stigmurus: biochemical and physiological comparison with other Tityus species. Comp Biochem Physiol C Toxicol Pharmacol 2007; 146:147-157. [PMID: 17270501 DOI: 10.1016/j.cbpc.2006.12.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 11/21/2006] [Accepted: 12/07/2006] [Indexed: 11/21/2022]
Abstract
The venom from the Brazilian scorpion Tityus stigmurus was fractionated by high performance liquid chromatography (HPLC) and the corresponding components were used for molecular mass determination using electrospray ion trap mass spectrometry. One hundred distinct components were clearly assigned showing molecular masses from 216.5 to 44,800.0 Da. Fifteen new components were isolated and sequenced, four of them to completion: Tst-3 (similar to Na(+) channel specific scorpion toxins), Tst-17 (a K(+) channel blocking peptide similar to Tc1), Tst beta KTx (a peptide with identical sequence as that of TsTX-K beta toxin earlier described to exist in T. serrulatus venom) and finally a novel proline-rich peptide of unknown function. Among the eleven components partially sequenced were two enzymes: hyaluronidase and lysozyme. The first enzyme has a molecular mass of 44,800.0 Da. This enzyme showed high activity against the substrate hyaluronan in vitro. Amino acid sequence of the second enzyme showed that it is similar to other known lysozymes, with similar molecular mass and sequence to that of bona fide lysozymes reported in public protein data banks. Finally, this communication reports a correlation among HPLC retention times and molecular masses of folded scorpion toxins as well as a comparative structural and physiological analysis of components from the venom of several species of the genus Tityus.
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Affiliation(s)
- C V F Batista
- Department of Molecular Medicine and Bioprocesses, Institute of Biotechnology, National Autonomous University of Mexico, Avenida Universidad, 2001, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - S A Román-González
- Department of Molecular Medicine and Bioprocesses, Institute of Biotechnology, National Autonomous University of Mexico, Avenida Universidad, 2001, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - S P Salas-Castillo
- Department of Molecular Medicine and Bioprocesses, Institute of Biotechnology, National Autonomous University of Mexico, Avenida Universidad, 2001, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - F Z Zamudio
- Department of Molecular Medicine and Bioprocesses, Institute of Biotechnology, National Autonomous University of Mexico, Avenida Universidad, 2001, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - F Gómez-Lagunas
- Department of Physiology, Medical School, National Autonomous University of Mexico, Ciudad Universitaria, Mexico D.F. 04510, Mexico
| | - L D Possani
- 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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Nolting A, Ferraro T, D'hoedt D, Stocker M. An amino acid outside the pore region influences apamin sensitivity in small conductance Ca2+-activated K+ channels. J Biol Chem 2006; 282:3478-86. [PMID: 17142458 PMCID: PMC1849974 DOI: 10.1074/jbc.m607213200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Small conductance calcium-activated potassium channels (SK, K(Ca)) are a family of voltage-independent K+ channels with a distinct physiology and pharmacology. The bee venom toxin apamin inhibits exclusively the three cloned SK channel subtypes (SK1, SK2, and SK3) with different affinity, highest for SK2, lowest for SK1, and intermediate for SK3 channels. The high selectivity of apamin made it a valuable tool to study the molecular makeup and function of native SK channels. Three amino acids located in the outer vestibule of the pore are of particular importance for the different apamin sensitivities of SK channels. Chimeric SK1 channels, enabling the homomeric expression of the rat SK1 (rSK1) subunit and containing the core domain (S1-S6) of rSK1, are apamin-insensitive. By contrast, channels formed by the human orthologue human SK1 (hSK1) are sensitive to apamin. This finding hinted at the involvement of regions beyond the pore as determinants of apamin sensitivity, because hSK1 and rSK1 have an identical amino acid sequence in the pore region. Here we investigated which parts of the channels outside the pore region are important for apamin sensitivity by constructing chimeras between apamin-insensitive and -sensitive SK channel subunits and by introducing point mutations. We demonstrate that a single amino acid situated in the extracellular loop between the transmembrane segments S3 and S4 has a major impact on apamin sensitivity. Our findings enabled us to convert the hSK1 channel into a channel that was as sensitive for apamin as SK2, the SK channel with the highest sensitivity.
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Affiliation(s)
- Andreas Nolting
- Laboratory of Molecular Pharmacology, Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
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35
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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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36
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Tan PTJ, Veeramani A, Srinivasan KN, Ranganathan S, Brusic V. SCORPION2: A database for structure–function analysis of scorpion toxins. Toxicon 2006; 47:356-63. [PMID: 16445955 DOI: 10.1016/j.toxicon.2005.12.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 12/01/2005] [Accepted: 12/06/2005] [Indexed: 10/25/2022]
Abstract
Scorpion toxins are important experimental tools for characterization of vast array of ion channels and serve as scaffolds for drug design. General public database entries contain limited annotation whereby rich structure-function information from mutation studies is typically not available. SCORPION2 contains more than 800 records of native and mutant toxin sequences enriched with binding affinity and toxicity information, 624 three-dimensional structures and some 500 references. SCORPION2 has a set of search and prediction tools that allow users to extract and perform specific queries: text searches of scorpion toxin records, sequence similarity search, extraction of sequences, visualization of scorpion toxin structures, analysis of toxic activity, and functional annotation of previously uncharacterized scorpion toxins. The SCORPION2 database is available at http://sdmc.i2r.a-star.edu.sg/scorpion/.
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Affiliation(s)
- Paul T J Tan
- Institute for Infocomm Research, 21 Heng Mui Keng Terrace, Singapore, Singapore 119613.
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37
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Barona J, Batista CVF, Zamudio FZ, Gomez-Lagunas F, Wanke E, Otero R, Possani LD. Proteomic analysis of the venom and characterization of toxins specific for Na+- and K+-channels from the Colombian scorpion Tityus pachyurus. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2006; 1764:76-84. [PMID: 16309982 DOI: 10.1016/j.bbapap.2005.08.010] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 08/10/2005] [Accepted: 08/15/2005] [Indexed: 11/23/2022]
Abstract
The Colombian scorpion Tityus pachyurus is toxic to humans and is capable of producing fatal accidents, but nothing is known about its venom components. This communication reports the separation of at least 57 fractions from the venom by high performance liquid chromatography. From these, at least 104 distinct molecular weight compounds were identified by mass spectrometry analysis. The complete amino acid sequences of three peptides were determined and the partial sequences of three others were also identified. Electrophysiological experiments conducted with ion-channels expressed heterologously on Sf9 cells showed the presence of a potent Shaker B K(+)-channel blocker. This peptide (trivial name Tpa1) contains 23 amino acid residues closely packed by three disulfide bridges with a molecular mass of 2,457 atomic mass units. It is the third member of the sub-family 13, for which the systematic name is proposed to be alpha-KTx13.3. The mice assay showed clearly the presence of toxic peptides to mammals. One of them named Tpa2, containing 65 amino acid residues with molecular mass of 7,522.5 atomic mass units, is stabilized by four disulfide bridges. It was shown to modify the Na(+)-currents of F-11 and TE671 cells in culture, similar to the beta scorpion toxins. These results demonstrate the presence of toxic peptides in the venom of T. pachyurus and confirm that accidents with this species of scorpion should be considered an important human hazard in Colombia.
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Affiliation(s)
- Jacqueline Barona
- 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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