1
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Collaço RDC, Van Petegem F, Bosmans F. ω-Grammotoxin-SIA inhibits voltage-gated Na+ channel currents. J Gen Physiol 2024; 156:e202413563. [PMID: 39042091 DOI: 10.1085/jgp.202413563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 06/14/2024] [Accepted: 07/10/2024] [Indexed: 07/24/2024] Open
Abstract
ω-Grammotoxin-SIA (GrTX-SIA) was originally isolated from the venom of the Chilean rose tarantula and demonstrated to function as a gating modifier of voltage-gated Ca2+ (CaV) channels. Later experiments revealed that GrTX-SIA could also inhibit voltage-gated K+ (KV) channel currents via a similar mechanism of action that involved binding to a conserved S3-S4 region in the voltage-sensing domains (VSDs). Since voltage-gated Na+ (NaV) channels contain homologous structural motifs, we hypothesized that GrTX-SIA could inhibit members of this ion channel family as well. Here, we show that GrTX-SIA can indeed impede the gating process of multiple NaV channel subtypes with NaV1.6 being the most susceptible target. Moreover, molecular docking of GrTX-SIA onto NaV1.6, supported by a p.E1607K mutation, revealed the voltage sensor in domain IV (VSDIV) as being a primary site of action. The biphasic manner in which current inhibition appeared to occur suggested a second, possibly lower-sensitivity binding locus, which was identified as VSDII by using KV2.1/NaV1.6 chimeric voltage-sensor constructs. Subsequently, the NaV1.6p.E782K/p.E838K (VSDII), NaV1.6p.E1607K (VSDIV), and particularly the combined VSDII/VSDIV mutant lost virtually all susceptibility to GrTX-SIA. Together with existing literature, our data suggest that GrTX-SIA recognizes modules in NaV channel VSDs that are conserved among ion channel families, thereby allowing it to act as a comprehensive ion channel gating modifier peptide.
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Affiliation(s)
- Rita de Cássia Collaço
- Department of Basic and Applied Medical Sciences, Molecular Physiology and Neurophysics Group, Ghent University, Ghent, Belgium
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
- Life Sciences Institute, University of British Columbia , Vancouver, Canada
| | - Frank Bosmans
- Department of Basic and Applied Medical Sciences, Molecular Physiology and Neurophysics Group, Ghent University, Ghent, Belgium
- Faculty of Medicine and Pharmacy, Center for Neurosciences (C4N), Vrije Universiteit Brussel , Brussels, Belgium
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2
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Tran P, Crawford T, Ragnarsson L, Deuis JR, Mobli M, Sharpe SJ, Schroeder CI, Vetter I. Structural Conformation and Activity of Spider-Derived Inhibitory Cystine Knot Peptide Pn3a Are Modulated by pH. ACS OMEGA 2023; 8:26276-26286. [PMID: 37521635 PMCID: PMC10373202 DOI: 10.1021/acsomega.3c02664] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/22/2023] [Indexed: 08/01/2023]
Abstract
Numerous spider venom-derived gating modifier toxins exhibit conformational heterogeneity during purification by reversed-phase high-performance liquid chromatography (RP-HPLC). This conformational exchange is especially peculiar for peptides containing an inhibitor cystine knot motif, which confers excellent structural stability under conditions that are not conducive to disulfide shuffling. This phenomenon is often attributed to proline cis/trans isomerization but has also been observed in peptides that do not contain a proline residue. Pn3a is one such peptide forming two chromatographically distinguishable peaks that readily interconvert following the purification of either conformer. The nature of this exchange was previously uncharacterized due to the fast rate of conversion in solution, making isolation of the conformers impossible. In the present study, an N-terminal modification of Pn3a enabled the isolation of the individual conformers, allowing activity assays to be conducted on the individual conformers using electrophysiology. The conformers were analyzed separately by nuclear magnetic resonance spectroscopy (NMR) to study their structural differences. RP-HPLC and NMR were used to study the mechanism of exchange. The later-eluting conformer was the active conformer with a rigid structure that corresponds to the published structure of Pn3a, while NMR analysis revealed the earlier-eluting conformer to be inactive and disordered. The exchange was found to be pH-dependent, arising in acidic solutions, possibly due to reversible disruption and formation of intramolecular salt bridges. This study reveals the nature of non-proline conformational exchange observed in Pn3a and possibly other disulfide-rich peptides, highlighting that the structure and activity of some disulfide-stabilized peptides can be dramatically susceptible to disruption.
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Affiliation(s)
- Poanna Tran
- Institute
for Molecular Bioscience, The University
of Queensland, Brisbane, Queensland 4072, Australia
| | - Theo Crawford
- Centre
for Advanced Imaging, The University of
Queensland, Brisbane, Queensland 4072, Australia
| | - Lotten Ragnarsson
- Institute
for Molecular Bioscience, The University
of Queensland, Brisbane, Queensland 4072, Australia
| | - Jennifer R. Deuis
- Institute
for Molecular Bioscience, The University
of Queensland, Brisbane, Queensland 4072, Australia
| | - Mehdi Mobli
- Centre
for Advanced Imaging, The University of
Queensland, Brisbane, Queensland 4072, Australia
| | - Simon J. Sharpe
- Molecular
Medicine Program, Research Institute, The
Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
- Department
of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Christina I. Schroeder
- Institute
for Molecular Bioscience, The University
of Queensland, Brisbane, Queensland 4072, Australia
- Center
for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702-1201, United States
- Genentech, 1 DNA Way, South San Francisco, California 94080, United States
| | - Irina Vetter
- Institute
for Molecular Bioscience, The University
of Queensland, Brisbane, Queensland 4072, Australia
- School
of Pharmacy, The University of Queensland, Brisbane, Queensland 4102, Australia
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3
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Sarkar D, Mishra S, Nisal R, Majhi S, Shrivas R, Singh Y, Anusree VS, Kalia J. Site-Specific Fluorescent Labeling of the Cysteine-Rich Toxin, DkTx, for TRPV1 Ion Channel Imaging and Membrane Binding Studies. Bioconjug Chem 2022; 33:1761-1770. [PMID: 36073164 DOI: 10.1021/acs.bioconjchem.2c00355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide toxins secreted by venomous animals bind to mammalian ion channel proteins and modulate their function. The high specificity of these toxins for their target ion channels enables them to serve as powerful tools for ion channel biology. Toxins labeled with fluorescent dyes are employed for the cellular imaging of channels and also for studying toxin-channel and toxin-membrane interactions. Several of these toxins are cysteine-rich, rendering the production of properly folded fluorescently labeled toxins technically challenging. Herein, we evaluate a variety of site-specific protein bioconjugation approaches for producing fluorescently labeled double-knot toxin (DkTx), a potent TRPV1 ion channel agonist that contains an uncommonly large number of cysteines (12 out of a total of 75 amino acids present in the protein). We find that popular cysteine-mediated bioconjugation approaches are unsuccessful as the introduction of a non-native cysteine residue for thiol modification leads to the formation of misfolded toxin species. Moreover, N-terminal aldehyde-mediated bioconjugation approaches are also not suitable as the resultant labeled toxin lacks activity. In contrast to these approaches, C-terminal bioconjugation of DkTx via the sortase bioconjugation technology yields functionally active fluorescently labeled DkTx. We employ this labeled toxin for imaging rat TRPV1 heterologously expressed in Xenopus laevis oocytes, as well as for performing membrane binding studies on giant unilamellar vesicles composed of different lipid compositions. Our studies set the stage for using fluorescent DkTx as a tool for TRPV1 biology and provide an informative blueprint for labeling cysteine-rich proteins.
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Affiliation(s)
- Debayan Sarkar
- Department of Biology, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Satyajit Mishra
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Rahul Nisal
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - Sumita Majhi
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Rohit Shrivas
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Yashaswi Singh
- Department of Biology, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - V S Anusree
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Jeet Kalia
- Department of Biology, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India.,Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.,Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
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Mellado G, Espinoza N, Garate JA, Neely A. Spider Toxin SNX-482 Gating Modifier Spontaneously Partitions in the Membrane Guided by Electrostatic Interactions. MEMBRANES 2022; 12:membranes12060595. [PMID: 35736302 PMCID: PMC9231009 DOI: 10.3390/membranes12060595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/30/2022] [Accepted: 06/02/2022] [Indexed: 11/16/2022]
Abstract
Spider toxin SNX-482 is a cysteine-rich peptide that interferes with calcium channel activity by binding to voltage-sensing domains of the CaV2.3 subtype. Two mechanisms dominate the binding process of cysteine-rich peptides.: direct binding from the aqueous phase or through lateral diffusion from the membrane, the so-called reduction in dimensionality mechanism. In this work, via coarse-grained and atomistic molecular dynamics simulations, we have systematically studied the spontaneous partitioning of SNX-482 with membranes of different anionic compositions and explored via diffusional analysis both binding mechanisms. Our simulations revealed a conserved protein patch that inserts in the membrane, a preference for binding towards partially negatively charged membranes, and that electrostatics guides membrane binding by incrementing and aligning the molecular dipole. Finally, diffusivity calculations showed that the toxin diffusion along the membrane plane is an order of magnitude slower than the aqueous phase suggesting that the critical factor in determining the SNX-482-CaV2.3 binding mechanism is the affinity between the membrane and SNX-482.
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Affiliation(s)
- Guido Mellado
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso 2362735, Chile; (G.M.); (N.E.)
- Biofisica y Biología Computacional, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso 2362735, Chile
| | - Nicolas Espinoza
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso 2362735, Chile; (G.M.); (N.E.)
- Biofisica y Biología Computacional, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso 2362735, Chile
- Millennium Nucleus in NanoBioPhysics, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso 2360102, Chile
| | - Jose Antonio Garate
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso 2362735, Chile; (G.M.); (N.E.)
- Millennium Nucleus in NanoBioPhysics, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso 2360102, Chile
- Centro Científico y Tecnológico de Excelencia Ciencia y Vida, Santiago 7750000, Chile
- Correspondence: (J.A.G.); (A.N.)
| | - Alan Neely
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso 2362735, Chile; (G.M.); (N.E.)
- Correspondence: (J.A.G.); (A.N.)
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5
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Fraser SP, Onkal R, Theys M, Bosmans F, Djamgoz MBA. Neonatal Na V 1.5: Pharmacological distinctiveness of a cancer-related voltage-gated sodium channel splice variant. Br J Pharmacol 2021; 179:473-486. [PMID: 34411279 DOI: 10.1111/bph.15668] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/26/2021] [Accepted: 07/31/2021] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Voltage-gated sodium (NaV ) channels are expressed de novo in carcinomas where their activity promotes invasiveness. Breast and colon cancer cells express the neonatal splice variant of NaV 1.5 (nNaV 1.5) which has several amino acid substitutions in the domain I voltage-sensor compared to its adult counterpart (aNaV 1.5). This study aimed to determine whether nNaV 1.5 could be distinguished pharmacologically from aNaV 1.5. EXPERIMENTAL APPROACH Cells expressing either nNaV 1.5 or aNaV 1.5 were exposed to small-molecule inhibitors, an antibody or natural toxins, and changes in electrophysiological parameters were measured. Stable expression in EBNA cells and transient expression in Xenopus laevis oocytes were used. Currents were recorded by whole-cell patch clamp and two-electrode voltage-clamp, respectively. KEY RESULTS Several clinically-used blockers of Nav channels (lidocaine, procaine, phenytoin, mexiletine, ranolazine and riluzole) could not distinguish between nNaV 1.5 or aNaV 1.5. On the other hand, two tarantula toxins (HaTx and ProTx-II) and a polyclonal antibody (NESOpAb) preferentially inhibited currents elicited by either nNaV 1.5 or aNaV 1.5 by binding to the spliced region of the channel. Furthermore, the amino acid residue at position 211 (aspartate in aNaV 1.5/lysine in nNaV 1.5), i.e. the charge reversal in the spliced region of the channel, played a key role in the selectivity especially in the antibody binding. CONCLUSION AND IMPLICATIONS We conclude that the cancer-related nNaV 1.5 channel can be distinguished pharmacologically from its nearest neighbour, aNaV 1.5. Thus, it may be possible to design small molecules as anti-metastatic drugs for non-toxic therapy of nNaV 1.5-expressing carcinomas.
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Affiliation(s)
- Scott P Fraser
- Imperial College London, Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, London, UK
| | - Rustem Onkal
- Imperial College London, Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, London, UK.,Biotechnology Research Centre, Cyprus International University, Haspolat, Nicosia, TRNC, Mersin 10, Turkey
| | - Margaux Theys
- Department of Basic and Applied Medical Sciences, University of Ghent, Ghent, Belgium
| | - Frank Bosmans
- Department of Basic and Applied Medical Sciences, University of Ghent, Ghent, Belgium
| | - Mustafa B A Djamgoz
- Imperial College London, Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, London, UK.,Biotechnology Research Centre, Cyprus International University, Haspolat, Nicosia, TRNC, Mersin 10, Turkey
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6
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Rashwan R, Hunt DM, Carvalho LS. The role of voltage-gated ion channels in visual function and disease in mammalian photoreceptors. Pflugers Arch 2021; 473:1455-1468. [PMID: 34255151 DOI: 10.1007/s00424-021-02595-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 05/31/2021] [Accepted: 06/10/2021] [Indexed: 12/26/2022]
Abstract
Light activation of the classical light-sensing retinal neurons, the photoreceptors, results in a graded change in membrane potential that ultimately leads to a reduction in neurotransmitter release to the post-synaptic retinal neurons. Photoreceptors show striking powers of adaptation, and for visual processing to function optimally, they must adjust their gain to remain responsive to different levels of ambient light intensity. The presence of a tightly controlled balance of inward and outward currents modulated by several different types of ion channels is what gives photoreceptors their remarkably dynamic operating range. Part of the resetting and modulation of this operating range is controlled by potassium and calcium voltage-gated channels, which are involved in setting the dark resting potential and synapse signal processing, respectively. Their essential contribution to visual processing is further confirmed in patients suffering from cone dystrophy with supernormal rod response (CDSRR) and congenital stationary night blindness type 2 (CSNB2), both conditions that lead to irreversible vision loss. This review will discuss these two types of voltage-gated ion channels present in photoreceptors, focussing on their structure and physiology, and their role in visual processing. It will also discuss the use and benefits of knockout mouse models to further study the function of these channels and what routes to potential treatments could be applied for CDSRR and CSNB2.
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Affiliation(s)
- Rabab Rashwan
- Lions Eye Institute, Nedlands, Western Australia, 6009, Australia
- Department of Microbiology and Immunology, Faculty of Medicine, Minia University, Minia, Egypt
| | - David M Hunt
- Lions Eye Institute, Nedlands, Western Australia, 6009, Australia
- Centre for Ophthalmology and Vision Science, The University of Western Australia, Perth, Western Australia, 6009, Australia
- School of Biological Sciences, University of Western Australia, Nedlands, Western Australia, 6009, Australia
| | - Livia S Carvalho
- Lions Eye Institute, Nedlands, Western Australia, 6009, Australia.
- Centre for Ophthalmology and Vision Science, The University of Western Australia, Perth, Western Australia, 6009, Australia.
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7
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Matsumura K, Yokogawa M, Osawa M. Peptide Toxins Targeting KV Channels. Handb Exp Pharmacol 2021; 267:481-505. [PMID: 34117930 DOI: 10.1007/164_2021_500] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
A number of peptide toxins isolated from animals target potassium ion (K+) channels. Many of them are particularly known to inhibit voltage-gated K+ (KV) channels and are mainly classified into pore-blocking toxins or gating-modifier toxins. Pore-blocking toxins directly bind to the ion permeation pores of KV channels, thereby physically occluding them. In contrast, gating-modifier toxins bind to the voltage-sensor domains of KV channels, modulating their voltage-dependent conformational changes. These peptide toxins are useful molecular tools in revealing the structure-function relationship of KV channels and have potential for novel treatments for diseases related to KV channels. This review focuses on the inhibition mechanism of pore-blocking and gating-modifier toxins that target KV channels.
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Affiliation(s)
- Kazuki Matsumura
- Graduate School of Pharmaceutical Sciences, Keio University, Tokyo, Japan
| | - Mariko Yokogawa
- Graduate School of Pharmaceutical Sciences, Keio University, Tokyo, Japan
| | - Masanori Osawa
- Graduate School of Pharmaceutical Sciences, Keio University, Tokyo, Japan.
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8
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Xiao Z, Zhao P, Wu X, Kong X, Wang R, Liang S, Tang C, Liu Z. Variation of Two S3b Residues in K V4.1-4.3 Channels Underlies Their Different Modulations by Spider Toxin κ-LhTx-1. Front Pharmacol 2021; 12:692076. [PMID: 34177600 PMCID: PMC8222713 DOI: 10.3389/fphar.2021.692076] [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: 04/07/2021] [Accepted: 05/27/2021] [Indexed: 11/13/2022] Open
Abstract
The naturally occurred peptide toxins from animal venoms are valuable pharmacological tools in exploring the structure-function relationships of ion channels. Herein we have identified the peptide toxin κ-LhTx-1 from the venom of spider Pandercetes sp (the Lichen huntsman spider) as a novel selective antagonist of the KV4 family potassium channels. κ-LhTx-1 is a gating-modifier toxin impeded KV4 channels' voltage sensor activation, and mutation analysis has confirmed its binding site on channels' S3b region. Interestingly, κ-LhTx-1 differently modulated the gating of KV4 channels, as revealed by toxin inhibiting KV4.2/4.3 with much more stronger voltage-dependence than that for KV4.1. We proposed that κ-LhTx-1 trapped the voltage sensor of KV4.1 in a much more stable resting state than that for KV4.2/4.3 and further explored the underlying mechanism. Swapping the non-conserved S3b segments between KV4.1(280FVPK283) and KV4.3(275VMTN278) fully reversed their voltage-dependence phenotypes in inhibition by κ-LhTx-1, and intensive mutation analysis has identified P282 in KV4.1, D281 in KV4.2 and N278 in KV4.3 being the key residues. Furthermore, the last two residues in this segment of each KV4 channel (P282/K283 in KV4.1, T280/D281 in KV4.2 and T277/N278 in KV4.3) likely worked synergistically as revealed by our combinatorial mutations analysis. The present study has clarified the molecular basis in KV4 channels for their different modulations by κ-LhTx-1, which have advanced our understanding on KV4 channels' structure features. Moreover, κ-LhTx-1 might be useful in developing anti-arrhythmic drugs given its high affinity, high selectivity and unique action mode in interacting with the KV4.2/4.3 channels.
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Affiliation(s)
- Zhen Xiao
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Piao Zhao
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Xiangyue Wu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Xiangjin Kong
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Ruiwen Wang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Songping Liang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Cheng Tang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Zhonghua Liu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
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9
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McArthur JR, Munasinghe NR, Finol-Urdaneta RK, Adams DJ, Christie MJ. Spider Venom Peptide Pn3a Inhibition of Primary Afferent High Voltage-Activated Calcium Channels. Front Pharmacol 2021; 11:633679. [PMID: 33584315 PMCID: PMC7875911 DOI: 10.3389/fphar.2020.633679] [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: 11/25/2020] [Accepted: 12/30/2020] [Indexed: 11/19/2022] Open
Abstract
Despite potently inhibiting the nociceptive voltage-gated sodium (Nav) channel, Nav1.7, µ-theraphotoxin Pn3a is antinociceptive only upon co-administration with sub-therapeutic opioid agonists, or by itself at doses >3,000-fold greater than its Nav1.7 IC50 by a yet undefined mechanism. Nav channels are structurally related to voltage-gated calcium (Cav) channels, Cav1 and Cav2. These channels mediate the high voltage-activated (HVA) calcium currents (ICa) that orchestrate synaptic transmission in nociceptive dorsal root ganglion (DRG) neurons and are fine-tuned by opioid receptor (OR) activity. Using whole-cell patch clamp recording, we found that Pn3a (10 µM) inhibits ∼55% of rat DRG neuron HVA-ICa and 60–80% of Cav1.2, Cav1.3, Cav2.1, and Cav2.2 mediated currents in HEK293 cells, with no inhibition of Cav2.3. As a major DRG ICa component, Cav2.2 inhibition by Pn3a (IC50 = 3.71 ± 0.21 µM) arises from an 18 mV hyperpolarizing shift in the voltage dependence of inactivation. We observed that co-application of Pn3a and µ-OR agonist DAMGO results in enhanced HVA-ICa inhibition in DRG neurons whereas co-application of Pn3a with the OR antagonist naloxone does not, underscoring HVA channels as shared targets of Pn3a and opioids. We provide evidence that Pn3a inhibits native and recombinant HVA Cavs at previously reportedly antinociceptive concentrations in animal pain models. We show additive modulation of DRG HVA-ICa by sequential application of low Pn3a doses and sub-therapeutic opioids ligands. We propose Pn3a's antinociceptive effects result, at least in part, from direct inhibition of HVA-ICa at high Pn3a doses, or through additive inhibition by low Pn3a and mild OR activation.
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Affiliation(s)
- Jeffrey R McArthur
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Nehan R Munasinghe
- Discipline of Pharmacology, University of Sydney, Sydney, NSW, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia.,Electrophysiology Facility for Cell Phenotyping and Drug Discovery, IHMRI, Wollongong, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
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10
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Armstrong DA, Jin AH, Braga Emidio N, Lewis RJ, Alewood PF, Rosengren KJ. Chemical Synthesis and NMR Solution Structure of Conotoxin GXIA from Conus geographus. Mar Drugs 2021; 19:md19020060. [PMID: 33530397 PMCID: PMC7912261 DOI: 10.3390/md19020060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/07/2021] [Accepted: 01/19/2021] [Indexed: 12/30/2022] Open
Abstract
Conotoxins are disulfide-rich peptides found in the venom of cone snails. Due to their exquisite potency and high selectivity for a wide range of voltage and ligand gated ion channels they are attractive drug leads in neuropharmacology. Recently, cone snails were found to have the capability to rapidly switch between venom types with different proteome profiles in response to predatory or defensive stimuli. A novel conotoxin, GXIA (original name G117), belonging to the I3-subfamily was identified as the major component of the predatory venom of piscivorous Conus geographus. Using 2D solution NMR spectroscopy techniques, we resolved the 3D structure for GXIA, the first structure reported for the I3-subfamily and framework XI family. The 32 amino acid peptide is comprised of eight cysteine residues with the resultant disulfide connectivity forming an ICK+1 motif. With a triple stranded β-sheet, the GXIA backbone shows striking similarity to several tarantula toxins targeting the voltage sensor of voltage gated potassium and sodium channels. Supported by an amphipathic surface, the structural evidence suggests that GXIA is able to embed in the membrane and bind to the voltage sensor domain of a putative ion channel target.
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Affiliation(s)
- David A. Armstrong
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072, Australia;
| | - Ai-Hua Jin
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (A.-H.J.); (N.B.E.); (R.J.L.); (P.F.A.)
| | - Nayara Braga Emidio
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (A.-H.J.); (N.B.E.); (R.J.L.); (P.F.A.)
| | - Richard J. Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (A.-H.J.); (N.B.E.); (R.J.L.); (P.F.A.)
| | - Paul F. Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; (A.-H.J.); (N.B.E.); (R.J.L.); (P.F.A.)
| | - K. Johan Rosengren
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072, Australia;
- Correspondence:
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11
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A selective NaV1.1 activator with potential for treatment of Dravet syndrome epilepsy. Biochem Pharmacol 2020; 181:113991. [DOI: 10.1016/j.bcp.2020.113991] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 04/21/2020] [Indexed: 12/19/2022]
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12
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Deng M, Jiang L, Luo X, Tao H, Liang S. Jingzhaotoxin-X, a gating modifier of Kv4.2 and Kv4.3 potassium channels purified from the venom of the Chinese tarantula Chilobrachys jingzhao. J Venom Anim Toxins Incl Trop Dis 2020; 26:e20190043. [PMID: 32536941 PMCID: PMC7269146 DOI: 10.1590/1678-9199-jvatitd-2019-0043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Background The tarantula Chilobrachys jingzhao is one of the largest venomous spiders in China. In previous studies, we purified and characterized at least eight peptides from C. jingzhao venom. In this report, we describe the purification and characterization of Jingzhaotoxin-X (JZTX-X), which selectively blocks Kv4.2 and Kv4.3 potassium channels. Methods JZTX-X was purified using a combination of cation-exchange HPLC and reverse-phase HPLC. The amino-acid sequence was determined by automated Edman degradation and confirmed by mass spectrometry (MS). Voltage-gated ion channel currents were recorded in HEK293t cells transiently transfected with a variety of ion channel constructs. In addition, the hyperalgesic activity of JZTX-X and the toxin´s effect on motor function were assessed in mice. Results JZTX-X contained 31 amino acids, with six cysteine residues that formed three disulfide bonds within an inhibitory cysteine knot (ICK) topology. In whole-cell voltage-clamp experiments, JZTX-X inhibited Kv4.2 and Kv4.3 potassium channels in a concentration- and voltage-dependent manner, without affecting other ion channels (Kv1.1, 1.2, 1.3, 2.1, delayed rectifier potassium channels, high- and low-voltage-activated Ca2+ channels, and voltage-gated sodium channels Nav1.5 and 1.7). JZTX-X also shifted the voltage-dependent channel activation to more depolarized potentials, whereas extreme depolarization caused reversible toxin binding to Kv4.2 channels. JZTX-X shifted the Kv4.2 and Kv4.3 activities towards a resting state, since at the resting potential the toxin completely inhibited the channels, even in the absence of an applied physical stimulus. Intrathecal or intraplantar injection of JZTX-X caused a long-lasting decrease in the mechanical nociceptive threshold (hyperalgesia) but had no effect on motor function as assessed in the rotarod test. Conclusions JZTX-X selectively suppresses Kv4.2 and Kv4.3 potassium channel activity in a concentration- and voltage-dependent manner and causes long-lasting mechanical hyperalgesia.
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Affiliation(s)
- Meichun Deng
- Department of Biochemistry and Molecular Biology, School of Life Sciences, Central South University, Changsha, Hunan 410013, China
| | - Liping Jiang
- Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha 410013, China
| | - Xuan Luo
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, 410081, China
| | - Huai Tao
- Department of Biochemistry and Molecular Biology, Hunan University of Chinese Medicine, Changsha 410208, Hunan, China
| | - Songping Liang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, 410081, China
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13
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Deng M, Jiang L, Luo X, Tao H, Liang S. Jingzhaotoxin-X, a gating modifier of Kv4.2 and Kv4.3 potassium channels purified from the venom of the Chinese tarantula Chilobrachys jingzhao. J Venom Anim Toxins Incl Trop Dis 2020. [DOI: 10.1590//1678-9199-jvatitd-2019-0043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
| | | | | | - Huai Tao
- Hunan University of Chinese Medicine, China
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14
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Kodirov SA. Tale of tail current. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 150:78-97. [PMID: 31238048 DOI: 10.1016/j.pbiomolbio.2019.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/22/2019] [Accepted: 06/20/2019] [Indexed: 02/07/2023]
Abstract
The largest biomass of channel proteins is located in unicellular organisms and bacteria that have no organs. However, orchestrated bidirectional ionic currents across the cell membrane via the channels are important for the functioning of organs of organisms, and equally concern both fauna or flora. Several ion channels are activated in the course of action potentials. One of the hallmarks of voltage-dependent channels is a 'tail current' - deactivation as observed after prior and sufficient activation predominantly at more depolarized potentials e.g. for Kv while upon hyperpolarization for HCN α subunits. Tail current also reflects the timing of channel closure that is initiated upon termination of stimuli. Finally, deactivation of currents during repolarization could be a selective estimate for given channel as in case of HERG, if dedicated long and more depolarized 'tail pulse' is used. Since from a holding potential of e.g. -70 mV are often a family of outward K+ currents comprising IA and IK are simultaneously activated in native cells.
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Affiliation(s)
- Sodikdjon A Kodirov
- Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia; Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA; Almazov Federal Heart, Blood and Endocrinology Centre, Saint Petersburg, 197341, Russia; Institute of Experimental Medicine, I. P. Pavlov Department of Physiology, Russian Academy of Medical Sciences, Saint Petersburg, Russia; Laboratory of Emotions' Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, 02-093, Poland.
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15
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Tabakmakher VM, Krylov NA, Kuzmenkov AI, Efremov RG, Vassilevski AA. Kalium 2.0, a comprehensive database of polypeptide ligands of potassium channels. Sci Data 2019; 6:73. [PMID: 31133708 PMCID: PMC6536513 DOI: 10.1038/s41597-019-0074-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 03/29/2019] [Indexed: 12/31/2022] Open
Abstract
Potassium channels are the most diverse group of ion channels in humans. They take vital parts in numerous physiological processes and their malfunction gives rise to a range of pathologies. In addition to small molecules, there is a wide selection of several hundred polypeptide ligands binding to potassium channels, the majority of which have been isolated from animal venoms. Until recently, only scorpion toxins received focused attention being systematically assembled in the manually curated Kalium database, but there is a diversity of well-characterized potassium channel ligands originating from other sources. To address this issue, here we present the updated and improved Kalium 2.0 that covers virtually all known polypeptide ligands of potassium channels and reviews all available pharmacological data. In addition to an expansion, we have introduced several new features to the database including posttranslational modification annotation, indication of ligand mode of action, BLAST search, and possibility of data export.
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Affiliation(s)
- Valentin M Tabakmakher
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
- School of Biomedicine, Far Eastern Federal University, Vladivostok, 690950, Russia
| | - Nikolay A Krylov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
- National Research University Higher School of Economics, Moscow, 101000, Russia
| | - Alexey I Kuzmenkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Roman G Efremov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
- National Research University Higher School of Economics, Moscow, 101000, Russia
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow Oblast, 141700, Russia
| | - Alexander A Vassilevski
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow Oblast, 141700, Russia.
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16
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Zhang Y, Luo J, He J, Rong M, Zeng X. JZTX-V Targets the Voltage Sensor in Kv4.2 to Inhibit I to Potassium Channels in Cardiomyocytes. Front Pharmacol 2019; 10:357. [PMID: 31040778 PMCID: PMC6476928 DOI: 10.3389/fphar.2019.00357] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Accepted: 03/21/2019] [Indexed: 12/16/2022] Open
Abstract
Kv4 potassium channels are responsible for transient outward K+ currents in the cardiac action potential (AP). Previous experiments by our group demonstrated that Jingzhaotoxin-V (JZTX-V) selectively inhibits A-type potassium channels. However, the specific effects of JZTX-V on the transient outward (Ito) current of cardiomyocytes and underlying mechanism of action remain unclear. In the current study, 100 nM JZTX-V effectively inhibited the Ito current and extended the action potential duration (APD) of neonatal rat ventricular myocytes (NRVM). We further analyzed the effects of JZTX-V on Kv4.2, a cloned channel believed to underlie the Ito current in rat cardiomyocytes. JZTX-V inhibited the Kv4.2 current with a half-maximal inhibitory concentration (IC50) of 13 ± 1.7 nM. To establish the molecular mechanism underlying the inhibitory action of JZTX-V on Kv4.2, we performed alanine scanning mutagenesis of Kv4.2 and JZTX-V and assessed the effects of the mutations on binding activities of the proteins. Interestingly, the Kv4.2 mutations V285A, F289A, and V290A reduced the affinity for JZTX-V while I275A and L277A increased the affinity for JZTX-V. Moreover, mutation of positively charged residues (R20 and K22) of JZTX-V and the hydrophobic patch (formed by W5, M6, and W7) led to a significant reduction in toxin sensitivity, indicating that the hydrophobic patch and electrostatic interactions played key roles in the binding of JZTX-V with Kv4.2. Data from our study have shed light on the specific roles and molecular mechanisms of JZTX-V in the regulation of Ito potassium channels and supported its utility as a potential novel antiarrhythmic drug.
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Affiliation(s)
- Yiya Zhang
- Department of Dermatology, Xiangya Hospital, Central South University, Changsha, China.,Key Laboratory of Organ Injury, Aging and Regenerative Medicine of Hunan Province, Central South University, Changsha, China.,The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Ji Luo
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Juan He
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Mingqiang Rong
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Xiongzhi Zeng
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
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17
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Bajaj S, Han J. Venom-Derived Peptide Modulators of Cation-Selective Channels: Friend, Foe or Frenemy. Front Pharmacol 2019; 10:58. [PMID: 30863305 PMCID: PMC6399158 DOI: 10.3389/fphar.2019.00058] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 01/18/2019] [Indexed: 01/31/2023] Open
Abstract
Ion channels play a key role in our body to regulate homeostasis and conduct electrical signals. With the help of advances in structural biology, as well as the discovery of numerous channel modulators derived from animal toxins, we are moving toward a better understanding of the function and mode of action of ion channels. Their ubiquitous tissue distribution and the physiological relevancies of their opening and closing suggest that cation channels are particularly attractive drug targets, and years of research has revealed a variety of natural toxins that bind to these channels and alter their function. In this review, we provide an introductory overview of the major cation ion channels: potassium channels, sodium channels and calcium channels, describe their venom-derived peptide modulators, and how these peptides provide great research and therapeutic value to both basic and translational medical research.
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Affiliation(s)
- Saumya Bajaj
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Jingyao Han
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
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18
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Hu Z, Chen B, Xiao Z, Zhou X, Liu Z. Transcriptomic Analysis of the Spider Venom Gland Reveals Venom Diversity and Species Consanguinity. Toxins (Basel) 2019; 11:toxins11020068. [PMID: 30682870 PMCID: PMC6409621 DOI: 10.3390/toxins11020068] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 01/09/2019] [Accepted: 01/19/2019] [Indexed: 11/16/2022] Open
Abstract
Selenocosmia jiafu (S. jiafu) has been recently identified as a new species of spider in China. It lives in the same habitat as various other venomous spiders, including Chilobrachys jingzhao (C. jingzhao), Selenocosmia huwena (S. huwena), and Macrothele raveni (M. raveni). The venom from these different species of spiders exhibits some similarities and some differences in terms of their biochemical and electrophysiological properties. With the objective to illustrate the diversity in venom peptide toxins and to establish the evolutionary relationship between different spider species, we first performed transcriptomic analysis on a cDNA library from the venom gland of S. jiafu. We identified 146 novel toxin-like sequences, which were classified into eighteen different superfamilies. This transcriptome was then compared with that of C. jingzhao, which revealed that the putative toxins from both spider venoms may have originated from the same ancestor, although novel toxins evolved independently in the two species. A BLAST search and pharmacological analysis revealed that the two venoms have similar sodium channel modulation activity. This study provides insights into the venom of two closely related species of spider, which will prove useful towards understanding the structure and function of their toxins.
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Affiliation(s)
- Zhaotun Hu
- Key Laboratory of Research and Utilization of Ethnomedicinal Plant Resources of Hunan Province, College of Biological and Food Engineering, Huaihua University, Huaihua 418008, China.
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Bo Chen
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Zhen Xiao
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Xi Zhou
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
| | - Zhonghua Liu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha 410081, China.
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19
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Zhao Y, Chen Z, Cao Z, Li W, Wu Y. Defensins, a novel type of animal toxin-like potassium channel inhibitor. Toxicon 2018; 157:101-105. [PMID: 30472109 DOI: 10.1016/j.toxicon.2018.11.304] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 11/03/2018] [Accepted: 11/19/2018] [Indexed: 12/29/2022]
Abstract
The classical potassium channel inhibitors are toxin peptides from venomous animals, and whether there are peptide inhibitors from other species is an open question. Due to both the independent and interdependent relationships between the spear (peptide inhibitors) and the shield (potassium channels), human defensins were first identified by our group as endogenous potassium channel inhibitors. Encouraged by the discovery of human defensins as potassium channel inhibitors, defensins from invertebrates and fungi were successively found by our group to be potassium channel inhibitors. In addition, a plant defensin was reported to be a potassium channel inhibitor. Since defensins are widely produced by vertebrate, invertebrate, plant and fungi species, the recent work established a new research field on defensin-potassium channel interactions. Here, we review the current work on defensins from vertebrate, invertebrate, plant and fungi species as inhibitors of potassium channels and discuss future work in this research field.
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Affiliation(s)
- Yonghui Zhao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Zongyun Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Department of Biochemistry and Molecular Biology, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China.
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20
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Tilley DC, Angueyra JM, Eum KS, Kim H, Chao LH, Peng AW, Sack JT. The tarantula toxin GxTx detains K + channel gating charges in their resting conformation. J Gen Physiol 2018; 151:292-315. [PMID: 30397012 PMCID: PMC6400525 DOI: 10.1085/jgp.201812213] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 10/01/2018] [Indexed: 11/20/2022] Open
Abstract
Allosteric ligands modulate protein activity by altering the energy landscape of conformational space in ligand-protein complexes. Here we investigate how ligand binding to a K+ channel's voltage sensor allosterically modulates opening of its K+-conductive pore. The tarantula venom peptide guangxitoxin-1E (GxTx) binds to the voltage sensors of the rat voltage-gated K+ (Kv) channel Kv2.1 and acts as a partial inverse agonist. When bound to GxTx, Kv2.1 activates more slowly, deactivates more rapidly, and requires more positive voltage to reach the same K+-conductance as the unbound channel. Further, activation kinetics are more sigmoidal, indicating that multiple conformational changes coupled to opening are modulated. Single-channel current amplitudes reveal that each channel opens to full conductance when GxTx is bound. Inhibition of Kv2.1 channels by GxTx results from decreased open probability due to increased occurrence of long-lived closed states; the time constant of the final pore opening step itself is not impacted by GxTx. When intracellular potential is less than 0 mV, GxTx traps the gating charges on Kv2.1's voltage sensors in their most intracellular position. Gating charges translocate at positive voltages, however, indicating that GxTx stabilizes the most intracellular conformation of the voltage sensors (their resting conformation). Kinetic modeling suggests a modulatory mechanism: GxTx reduces the probability of voltage sensors activating, giving the pore opening step less frequent opportunities to occur. This mechanism results in K+-conductance activation kinetics that are voltage-dependent, even if pore opening (the rate-limiting step) has no inherent voltage dependence. We conclude that GxTx stabilizes voltage sensors in a resting conformation, and inhibits K+ currents by limiting opportunities for the channel pore to open, but has little, if any, direct effect on the microscopic kinetics of pore opening. The impact of GxTx on channel gating suggests that Kv2.1's pore opening step does not involve movement of its voltage sensors.
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Affiliation(s)
- Drew C Tilley
- Department of Physiology & Membrane Biology, University of California, Davis, Davis, CA
| | - Juan M Angueyra
- Neurobiology Course, Marine Biological Laboratory, Woods Hole, MA
| | - Kenneth S Eum
- Department of Physiology & Membrane Biology, University of California, Davis, Davis, CA.,Neurobiology Course, Marine Biological Laboratory, Woods Hole, MA
| | - Heesoo Kim
- Neurobiology Course, Marine Biological Laboratory, Woods Hole, MA
| | - Luke H Chao
- Neurobiology Course, Marine Biological Laboratory, Woods Hole, MA
| | - Anthony W Peng
- Neurobiology Course, Marine Biological Laboratory, Woods Hole, MA
| | - Jon T Sack
- Department of Physiology & Membrane Biology, University of California, Davis, Davis, CA .,Neurobiology Course, Marine Biological Laboratory, Woods Hole, MA.,Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA
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21
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Démares F, Coquerel Q, Richoux G, Linthicum K, Bloomquist J. Fatty Acid and Related Potassium Kv2 Channel Blockers: Toxicity and Physiological Actions on Mosquitoes. INSECTS 2018; 9:E155. [PMID: 30388752 PMCID: PMC6315728 DOI: 10.3390/insects9040155] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 10/19/2018] [Accepted: 10/30/2018] [Indexed: 11/17/2022]
Abstract
Potassium channels constitute a very diverse group involved in neural signaling, neuronal activity, membrane potential maintenance, and action potential generation. Here, we tested the mammalian potassium channel blockers TRAM-34 and 5-hydroxydecanoate (5-HDC), as well as certain fatty acids (FA) that might fit in the lumen of the pore and block channel activity by obstructing K⁺ ion passage. Kv channel blockers could be leads for a novel pesticide type. Insecticidal activity was assessed by topical application to Anopheles gambiae adult mosquitoes, paralysis in a headless larval assay, at the cellular level with patch-clamp recordings of engineered HEK cells expressing AgKv2.1 channels, as well as central nervous system recordings from larval Drosophila melanogaster. With only one hydroxyl group difference, decanoic acid had a consistently greater effect than 5-HDC in blocking Kv channels, paralyzing larvae, and killing mosquitoes. The 11-dansylamino undecanoic acid (DAUDA) blockage of eukaryotic Kv channels is demonstrated for the first time, but it failed to kill adult mosquitoes. We synthesized alkyl esters from DAUDA and decanoic acid in an effort to improve cuticular penetration, but it had little impact upon adult toxicity. TRAM-34 and rolipram did not show activity on Kv channels nor potent insecticidal effect on adult mosquitoes. Furthermore, co-application of test compounds with permethrin did not increase mortality in adults. In conclusion, the compounds tested had modest insecticidal and synergistic activity.
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Affiliation(s)
- Fabien Démares
- Neurotoxicology Laboratory, Department of Entomology and Nematology, Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
| | - Quentin Coquerel
- Neurotoxicology Laboratory, Department of Entomology and Nematology, Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
| | - Gary Richoux
- Neurotoxicology Laboratory, Department of Entomology and Nematology, Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
| | - Kenneth Linthicum
- USDA, ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32608, USA.
| | - Jeffrey Bloomquist
- Neurotoxicology Laboratory, Department of Entomology and Nematology, Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
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22
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Sarkar D, Singh Y, Kalia J. Protein-Lipid Interfaces Can Drive the Functions of Membrane-Embedded Protein-Protein Complexes. ACS Chem Biol 2018; 13:2689-2698. [PMID: 30080384 PMCID: PMC6326545 DOI: 10.1021/acschembio.8b00644] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The roles of surrounding membrane lipids in the functions of transmembrane and peripheral membrane proteins are largely unknown. Herein, we utilize the recently reported structures of the TRPV1 ion channel protein bound to its potent protein agonist, the double-knot toxin (DkTx), as a model system to investigate the roles of toxin-lipid interfaces in TRPV1 activation by characterizing a series of DkTx variants electrophysiologically. Together with membrane partitioning experiments, these studies reveal that toxin-lipid interfaces play an overwhelmingly dominant role in channel activation as compared to lipid-devoid toxin-channel interfaces. Additionally, we find that whereas the membrane interfaces formed by one of the knots of the toxin endow it with its low channel-dissociation rate, those formed by other knot contribute primarily to its potency. These studies establish that protein-lipid interfaces play nuanced yet profound roles in the function of protein-protein complexes within membranes.
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Affiliation(s)
- Debayan Sarkar
- Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune−411008, Maharashtra, India
| | - Yashaswi Singh
- Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune−411008, Maharashtra, India
| | - Jeet Kalia
- Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune−411008, Maharashtra, India
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23
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Polido G, Shi X, Xu D, Guo C, Thai R, Patterson JP, Gianneschi NC, Suchyna TM, Sachs F, Holland GP. Investigating the interaction of Grammostola rosea venom peptides and model lipid bilayers with solid-state NMR and electron microscopy techniques. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:151-160. [PMID: 30463698 DOI: 10.1016/j.bbamem.2018.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/19/2018] [Accepted: 08/07/2018] [Indexed: 10/28/2022]
Abstract
Spider venom contains a number of small peptides that can control the gating properties of a wide range of ion channels with high affinity and specificity. These ion channels are responsible for coordination and control of many bodily functions such as transducing signals into sensory functions, smooth muscle contractions as well as serving as sensors in volume regulation. Hence, these peptides have been the topic of many research efforts in hopes that they can be used as biomedical therapeutics. Several peptides are known to control the gating properties of ion channels by involving the lipid membrane. GsMTx4, originally isolated from the Chilean Rose tarantula (Grammostola rosea), is known to selectively inhibit mechanosensitive ion channels by partitioning into the lipid bilayer. To further understand this indirect gating mechanism, we investigated the interactions between native GsAF2, VsTx1 and a synthetic form of GsMTx4 with model DMPC lipid bilayers using 31P solid-state NMR, 13C CP-MAS NMR, NS-TEM and cryo-TEM. The results reveal that these inhibitor cystine knot peptides perforate the DMPC lipid vesicles similarly with some subtle differences and ultimately create small spherical vesicles and anisotropic cylindrical and discoidal vesicles at concentrations near 1.0-1.5 mol% peptide. The anisotropic components align with their long axes along the NMR static B0 magnetic field, a property that should be useful in future NMR structural investigations of these systems. These findings move us forward in our understanding of how these peptides bind and interact with the lipid bilayer.
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Affiliation(s)
- Geraldine Polido
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182-1030, USA
| | - Xiangyan Shi
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Dian Xu
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Chengchen Guo
- Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Rich Thai
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182-1030, USA
| | - Joseph P Patterson
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Nathan C Gianneschi
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Thomas M Suchyna
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, USA
| | - Frederick Sachs
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, USA
| | - Gregory P Holland
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182-1030, USA.
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Pluskal T, Weng JK. Natural product modulators of human sensations and mood: molecular mechanisms and therapeutic potential. Chem Soc Rev 2018; 47:1592-1637. [PMID: 28933478 DOI: 10.1039/c7cs00411g] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Humans perceive physical information about the surrounding environment through their senses. This physical information is registered by a collection of highly evolved and finely tuned molecular sensory receptors. A multitude of bioactive, structurally diverse ligands have evolved in nature that bind these molecular receptors. The complex, dynamic interactions between the ligands and the receptors lead to changes in our sensory perception or mood. Here, we review our current knowledge of natural products and their derived analogues that interact specifically with human G protein-coupled receptors, ion channels, and nuclear hormone receptors to modulate the sensations of taste, smell, temperature, pain, and itch, as well as mood and its associated behaviour. We discuss the molecular and structural mechanisms underlying such interactions and highlight cases where subtle differences in natural product chemistry produce drastic changes in functional outcome. We also discuss cases where a single compound triggers complex sensory or behavioural changes in humans through multiple mechanistic targets. Finally, we comment on the therapeutic potential of the reviewed area of research and draw attention to recent technological developments in genomics, metabolomics, and metabolic engineering that allow us to tap the medicinal properties of natural product chemistry without taxing nature.
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Affiliation(s)
- Tomáš Pluskal
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA.
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25
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Lee MT. Biophysical characterization of peptide–membrane interactions. ADVANCES IN PHYSICS: X 2018. [DOI: 10.1080/23746149.2017.1408428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Ming-Tao Lee
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
- Department of Physics, National Central University, Jhongli, Taiwan
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26
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Pain-Causing Venom Peptides: Insights into Sensory Neuron Pharmacology. Toxins (Basel) 2017; 10:toxins10010015. [PMID: 29280959 PMCID: PMC5793102 DOI: 10.3390/toxins10010015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 12/19/2022] Open
Abstract
Venoms are produced by a wide variety of species including spiders, scorpions, reptiles, cnidarians, and fish for the purpose of harming or incapacitating predators or prey. While some venoms are of relatively simple composition, many contain hundreds to thousands of individual components with distinct pharmacological activity. Pain-inducing or "algesic" venom compounds have proven invaluable to our understanding of how physiological nociceptive neural networks operate. In this review, we present an overview of some of the diverse nociceptive pathways that can be modulated by specific venom components to evoke pain.
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Geron M, Hazan A, Priel A. Animal Toxins Providing Insights into TRPV1 Activation Mechanism. Toxins (Basel) 2017; 9:toxins9100326. [PMID: 29035314 PMCID: PMC5666373 DOI: 10.3390/toxins9100326] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 10/13/2017] [Accepted: 10/13/2017] [Indexed: 02/06/2023] Open
Abstract
Beyond providing evolutionary advantages, venoms offer unique research tools, as they were developed to target functionally important proteins and pathways. As a key pain receptor in the nociceptive pathway, transient receptor potential vanilloid 1 (TRPV1) of the TRP superfamily has been shown to be a target for several toxins, as a way of producing pain to deter predators. Importantly, TRPV1 is involved in thermoregulation, inflammation, and acute nociception. As such, toxins provide tools to understand TRPV1 activation and modulation, a critical step in advancing pain research and the development of novel analgesics. Indeed, the phytotoxin capsaicin, which is the spicy chemical in chili peppers, was invaluable in the original cloning and characterization of TRPV1. The unique properties of each subsequently characterized toxin have continued to advance our understanding of functional, structural, and biophysical characteristics of TRPV1. By building on previous reviews, this work aims to provide a comprehensive summary of the advancements made in TRPV1 research in recent years by employing animal toxins, in particular DkTx, RhTx, BmP01, Echis coloratus toxins, APHCs and HCRG21. We examine each toxin’s functional aspects, behavioral effects, and structural features, all of which have contributed to our current knowledge of TRPV1. We additionally discuss the key features of TRPV1’s outer pore domain, which proves to be the target of the currently discussed toxins.
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Affiliation(s)
- Matan Geron
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
| | - Adina Hazan
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
| | - Avi Priel
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
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Jiménez-Vargas JM, Possani LD, Luna-Ramírez K. Arthropod toxins acting on neuronal potassium channels. Neuropharmacology 2017; 127:139-160. [PMID: 28941737 DOI: 10.1016/j.neuropharm.2017.09.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 01/01/2023]
Abstract
Arthropod venoms are a rich mixture of biologically active compounds exerting different physiological actions across diverse phyla and affecting multiple organ systems including the central nervous system. Venom compounds can inhibit or activate ion channels, receptors and transporters with high specificity and affinity providing essential insights into ion channel function. In this review, we focus on arthropod toxins (scorpions, spiders, bees and centipedes) acting on neuronal potassium channels. A brief description of the K+ channels classification and structure is included and a compendium of neuronal K+ channels and the arthropod toxins that modify them have been listed. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Juana María Jiménez-Vargas
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad, 2001, Colonia Chamilpa, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - Lourival D Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad, 2001, Colonia Chamilpa, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - Karen Luna-Ramírez
- Illawarra Health and Medical Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.
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Yang S, Yang F, Zhang B, Lee BH, Li B, Luo L, Zheng J, Lai R. A bimodal activation mechanism underlies scorpion toxin-induced pain. SCIENCE ADVANCES 2017; 3:e1700810. [PMID: 28782041 PMCID: PMC5540258 DOI: 10.1126/sciadv.1700810] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/28/2017] [Indexed: 05/17/2023]
Abstract
Venomous animals use peptide toxins for hunting and self-defense. To achieve these goals, toxins need to bind to their targets with high affinity due to the small amount that a single bite or sting can deliver. The scorpion toxin BmP01 is linked to sting-induced excruciating pain; however, the reported minimum concentrations for activating TRPV1 channel or inhibiting voltage-gated potassium (Kv) channels (both in the micromolar range) appear too high to be biologically relevant. We show that the effective concentration of BmP01 is highly pH-dependent-it increases by about 10-fold in inhibiting Kv channels upon a 1-U drop in pH but decreases more than 100-fold in activating TRPV1. Mechanistic investigation revealed that BmP01 binds to one of the two proton-binding sites on TRPV1 and, together with a proton, uses a one-two punch approach to strongly activate the nociceptive channel. Because most animal venoms are acidic, proton-facilitated synergistic action may represent a general strategy for maximizing toxin potency.
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Affiliation(s)
- Shilong Yang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan 650223, China
| | - Fan Yang
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Bei Zhang
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Bo Hyun Lee
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
| | - Bowen Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan 650223, China
| | - Lei Luo
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan 650223, China
| | - Jie Zheng
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA
- Corresponding author. (J.Z.); (R.L.)
| | - Ren Lai
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan 650223, China
- Corresponding author. (J.Z.); (R.L.)
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Robinson SD, Safavi-Hemami H. Venom peptides as pharmacological tools and therapeutics for diabetes. Neuropharmacology 2017; 127:79-86. [PMID: 28689026 DOI: 10.1016/j.neuropharm.2017.07.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 06/24/2017] [Accepted: 07/04/2017] [Indexed: 12/31/2022]
Abstract
Diabetes mellitus is a chronic disease caused by a deficiency in production of insulin by the beta cells of the pancreas (type 1 diabetes, T1D), or by partial deficiency of insulin production and the ineffectiveness of the insulin produced (type 2 diabetes, T2D). Animal venoms are a unique source of compounds targeting ion channels and receptors in the nervous and cardiovascular systems. In recent years, several venom peptides have also emerged as pharmacological tools and therapeutics for T1D and T2D. Some of these peptides act directly as mimics of endogenous metabolic hormones while others act on ion channels expressed in pancreatic beta cells. Here, we provide an overview of the discovery of these venom peptides, their mechanisms of action in the context of diabetes, and their therapeutic potential for the treatment of this disease. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Samuel D Robinson
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
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31
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Agwa AJ, Henriques ST, Schroeder CI. Gating modifier toxin interactions with ion channels and lipid bilayers: Is the trimolecular complex real? Neuropharmacology 2017; 127:32-45. [PMID: 28400258 DOI: 10.1016/j.neuropharm.2017.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 03/31/2017] [Accepted: 04/05/2017] [Indexed: 11/15/2022]
Abstract
Spider peptide toxins have attracted attention because of their ability to target voltage-gated ion channels, which are involved in several pathologies including chronic pain and some cardiovascular conditions. A class of these peptides acts by modulating the gating mechanism of voltage-gated ion channels and are thus called gating modifier toxins (GMTs). In addition to their interactions with voltage-gated ion channels, some GMTs have affinity for lipid bilayers. This review discusses the potential importance of the cell membrane on the mode of action of GMTs. We propose that peptide-membrane interactions can anchor GMTs at the cell surface, thereby increasing GMT concentration in the vicinity of the channel binding site. We also propose that modulating peptide-membrane interactions might be useful for increasing the therapeutic potential of spider toxins. Furthermore, we explore the advantages and limitations of the methodologies currently used to examine peptide-membrane interactions. Although GMT-lipid membrane binding does not appear to be a requirement for the activity of all GMTs, it is an important feature, and future studies with GMTs should consider the trimolecular peptide-lipid membrane-channel complex. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Akello J Agwa
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sónia T Henriques
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Christina I Schroeder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
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Hsieh MH, Shiau YS, Liou HH, Jeng US, Lee MT, Lou KL. Measurement of Hanatoxin-Induced Membrane Thinning with Lamellar X-ray Diffraction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2885-2889. [PMID: 28260386 DOI: 10.1021/acs.langmuir.7b00064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Membrane perturbation induced by cysteine-rich peptides is a crucial biological phenomenon but scarcely investigated, in particular with effective biophysical-chemical methodologies. Hanatoxin (HaTx), a 35-residue polypeptide from spider venom, works as an inhibitor of drk1 (Kv2.1) channels, most likely by interacting with the voltage-sensor. However, how this water-soluble peptide modifies the gating remains poorly understood, as the voltage sensor was proposed to be deeply embedded within the bilayer. To see how HaTx interacts with phospholipid bilayers, we observe the toxin-induced perturbation on POPC/DOPG-membranes through measurements of the change in membrane thickness. Lamellar X-ray diffraction (LXD) was applied on stacked planar bilayers in the near-fully hydrated state. The results provide quantitative evidence for the membrane thinning in a concentration-dependent manner, leading to novel and direct combinatory approaches by discovering how to investigate such a biologically relevant interaction between gating-modifier toxins and phospholipid bilayers.
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Affiliation(s)
- Meng-Hsuan Hsieh
- Institute of Biotechnology, National Taiwan University , Taipei 10672, Taiwan
| | - Yu-Shuan Shiau
- Membrane Protein Research Core, Center for Biotechnology, National Taiwan University , Taipei 10672, Taiwan
| | - Horng-Huei Liou
- Division of Neurology, National Taiwan University Hospital , Taipei 10002, Taiwan
- Institute of Pharmacology, National Taiwan University , Taipei 10051, Taiwan
| | - U-Ser Jeng
- National Synchrotron Radiation Research Center , Hsinchu 30076, Taiwan
| | - Ming-Tao Lee
- National Synchrotron Radiation Research Center , Hsinchu 30076, Taiwan
- Department of Physics, National Central University , Jhongli 32001, Taiwan
| | - Kuo-Long Lou
- Institute of Biotechnology, National Taiwan University , Taipei 10672, Taiwan
- Membrane Protein Research Core, Center for Biotechnology, National Taiwan University , Taipei 10672, Taiwan
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Hanatoxin inserts into phospholipid membranes without pore formation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:917-923. [PMID: 28143758 DOI: 10.1016/j.bbamem.2017.01.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 01/21/2017] [Accepted: 01/26/2017] [Indexed: 11/23/2022]
Abstract
Hanatoxin (HaTx), a 35-residue polypeptide from spider venom, functions as an inhibitor of Kv2.1 channels by interacting with phospholipids prior to affecting the voltage-sensor. However, how this water-soluble peptide modifies the gating remains poorly understood, as the voltage-sensor is deeply embedded within the bilayer. To determine how HaTx interacts with phospholipid bilayers, in this study, we examined the toxin-induced partitioning of liposomal membranes. HPLC-results from high-speed spin-down vesicles with HaTx demonstrated direct binding. Dynamic light scattering (DLS) and leakage assay results further indicated that neither membrane pores nor membrane fragmentations were observed in the presence of HaTx. To clarify the binding details, Langmuir trough experiments were performed with phospholipid monolayers by mimicking the external leaflet of membrane bilayers, indicating the involvement of acyl chains in such interactions between HaTx and phospholipids. Our current study thus describes the interaction pattern of HaTx with vesicle membranes, defining a membrane-partitioning mechanism for peptide insertion involving the membrane hydrocarbon core without pore formation.
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Dromedary immune response and specific Kv2.1 antibody generation using a specific immunization approach. Int J Biol Macromol 2016; 93:167-171. [DOI: 10.1016/j.ijbiomac.2016.06.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 06/10/2016] [Accepted: 06/11/2016] [Indexed: 01/11/2023]
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Molecular Diversity between Salivary Proteins from New World and Old World Sand Flies with Emphasis on Bichromomyia olmeca, the Sand Fly Vector of Leishmania mexicana in Mesoamerica. PLoS Negl Trop Dis 2016; 10:e0004771. [PMID: 27409591 PMCID: PMC4943706 DOI: 10.1371/journal.pntd.0004771] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 05/21/2016] [Indexed: 01/30/2023] Open
Abstract
Background Sand fly saliva has been shown to have proteins with potent biological activities, salivary proteins that can be used as biomarkers of vector exposure, and salivary proteins that are candidate vaccines against different forms of leishmaniasis. Sand fly salivary gland transcriptomic approach has contributed significantly to the identification and characterization of many of these salivary proteins from important Leishmania vectors; however, sand fly vectors in some regions of the world are still neglected, as Bichromomyia olmeca (formerly known as Lutzomyia olmeca olmeca), a proven vector of Leishmania mexicana in Mexico and Central America. Despite the importance of this vector in transmitting Leishmania parasite in Mesoamerica there is no information on the repertoire of B. olmeca salivary proteins and their relationship to salivary proteins from other sand fly species. Methods and Findings A cDNA library of the salivary glands of wild-caught B. olmeca was constructed, sequenced, and analyzed. We identified transcripts encoding for novel salivary proteins from this sand fly species and performed a comparative analysis between B. olmeca salivary proteins and those from other sand fly species. With this new information we present an updated catalog of the salivary proteins specific to New World sand flies and salivary proteins common to all sand fly species. We also report in this work the anti-Factor Xa activity of Lofaxin, a salivary anticoagulant protein present in this sand fly species. Conclusions This study provides information on the first transcriptome of a sand fly from Mesoamerica and adds information to the limited repertoire of salivary transcriptomes from the Americas. This comparative analysis also shows a fast degree of evolution in salivary proteins from New World sand flies as compared with Old World sand flies. Leishmaniasis is a neglected disease caused by a parasite transmitted to the host by the bite of an infected sand fly. Sand fly saliva contains biologically active components that allow the sand fly to take a blood meal and also the parasite to spread in the host by countering the host immune mechanisms that fights the parasite. Research on sand fly saliva has allowed us to understand the biological functions of some of these proteins, to identify salivary proteins producing an immune response in different hosts and to select potential salivary vaccine that could be used to protect the host against the parasite. However, vectors transmitting different species of Leishmania in diverse regions of the world are still neglected. The present work focuses on the identification of the secreted proteins from the saliva of B. olmeca, a vector of Leishmania mexicana in North and Central America. We catalogued these proteins with those previously identified in other sand fly species from Old and New World. We showed here how conserved or divergent are these proteins families when comparing different sand fly species. We also report the anti-Factor Xa activity of Lofaxin, a salivary anticoagulant protein identified in the saliva of this sand fly species.
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Zhou TT, Quan LL, Chen LP, Du T, Sun KX, Zhang JC, Yu L, Li Y, Wan P, Chen LL, Jiang BH, Hu LH, Chen J, Shen X. SP6616 as a new Kv2.1 channel inhibitor efficiently promotes β-cell survival involving both PKC/Erk1/2 and CaM/PI3K/Akt signaling pathways. Cell Death Dis 2016; 7:e2216. [PMID: 27148689 PMCID: PMC4917657 DOI: 10.1038/cddis.2016.119] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 04/07/2016] [Accepted: 04/11/2016] [Indexed: 12/31/2022]
Abstract
Kv2.1 as a voltage-gated potassium (Kv) channel subunit has a pivotal role in the regulation of glucose-stimulated insulin secretion (GSIS) and pancreatic β-cell apoptosis, and is believed to be a promising target for anti-diabetic drug discovery, although the mechanism underlying the Kv2.1-mediated β-cell apoptosis is obscure. Here, the small molecular compound, ethyl 5-(3-ethoxy-4-methoxyphenyl)-2-(4-hydroxy-3-methoxybenzylidene)-7-methyl-3-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-6-carboxylate (SP6616) was discovered to be a new Kv2.1 inhibitor. It was effective in both promoting GSIS and protecting β cells from apoptosis. Evaluation of SP6616 on either high-fat diet combined with streptozocin-induced type 2 diabetic mice or db/db mice further verified its efficacy in the amelioration of β-cell dysfunction and glucose homeostasis. SP6616 treatment efficiently increased serum insulin level, restored β-cell mass, decreased fasting blood glucose and glycated hemoglobin levels, and improved oral glucose tolerance. Mechanism study indicated that the promotion of SP6616 on β-cell survival was tightly linked to its regulation against both protein kinases C (PKC)/extracellular-regulated protein kinases 1/2 (Erk1/2) and calmodulin(CaM)/phosphatidylinositol 3-kinase(PI3K)/serine/threonine-specific protein kinase (Akt) signaling pathways. To our knowledge, this may be the first report on the underlying pathway responsible for the Kv2.1-mediated β-cell protection. In addition, our study has also highlighted the potential of SP6616 in the treatment of type 2 diabetes.
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Affiliation(s)
- T T Zhou
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - L L Quan
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, China
| | - L P Chen
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - T Du
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - K X Sun
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - J C Zhang
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, China
| | - L Yu
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Y Li
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - P Wan
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, China
| | - L L Chen
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - B H Jiang
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - L H Hu
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - J Chen
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - X Shen
- CAS Key Laboratory of Receptor Research, 3th Department of Pharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
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Kuzmenkov AI, Grishin EV, Vassilevski AA. Diversity of Potassium Channel Ligands: Focus on Scorpion Toxins. BIOCHEMISTRY (MOSCOW) 2016; 80:1764-99. [DOI: 10.1134/s0006297915130118] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Computational Studies of Venom Peptides Targeting Potassium Channels. Toxins (Basel) 2015; 7:5194-211. [PMID: 26633507 PMCID: PMC4690127 DOI: 10.3390/toxins7124877] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 11/13/2015] [Accepted: 11/20/2015] [Indexed: 01/18/2023] Open
Abstract
Small peptides isolated from the venom of animals are potential scaffolds for ion channel drug discovery. This review article mainly focuses on the computational studies that have advanced our understanding of how various toxins interfere with the function of K+ channels. We introduce the computational tools available for the study of toxin-channel interactions. We then discuss how these computational tools have been fruitfully applied to elucidate the mechanisms of action of a wide range of venom peptides from scorpions, spiders, and sea anemone.
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Osmakov DI, Andreev YA, Kozlov SA. Acid-sensing ion channels and their modulators. BIOCHEMISTRY (MOSCOW) 2015; 79:1528-45. [PMID: 25749163 DOI: 10.1134/s0006297914130069] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
According to a modern look acid-sensing ion channels (ASICs) are one of the most important receptors that perceive pH change in the body. ASICs represent proton-gated Na+-selective channels, which are expressed in neurons of the central and peripheral nervous system. These channels are attracting attention of researchers around the world, as they are involved in various physiological processes in the body. Drop of pH may occur in tissues in norm (e.g. the accumulation of lactic acid, the release of protons upon ATP hydrolysis) and pathology (inflammation, ischemic stroke, tissue damage and seizure). These processes are accompanied by unpleasant pain sensations, which may be short-lived or can lead to chronic inflammatory diseases. Modulators of ASIC channels activity are potential candidates for new effective analgesic and neuroprotection drugs. This review summarizes available information about structure, function, and physiological role of ASIC channels. In addition a description of all known ligands of these channels and their practical relevance is provided.
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Affiliation(s)
- D I Osmakov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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Gupta K, Zamanian M, Bae C, Milescu M, Krepkiy D, Tilley DC, Sack JT, Yarov-Yarovoy V, Kim JI, Swartz KJ. Tarantula toxins use common surfaces for interacting with Kv and ASIC ion channels. eLife 2015; 4:e06774. [PMID: 25948544 PMCID: PMC4423116 DOI: 10.7554/elife.06774] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/16/2015] [Indexed: 12/14/2022] Open
Abstract
Tarantula toxins that bind to voltage-sensing domains of voltage-activated ion channels are thought to partition into the membrane and bind to the channel within the bilayer. While no structures of a voltage-sensor toxin bound to a channel have been solved, a structural homolog, psalmotoxin (PcTx1), was recently crystalized in complex with the extracellular domain of an acid sensing ion channel (ASIC). In the present study we use spectroscopic, biophysical and computational approaches to compare membrane interaction properties and channel binding surfaces of PcTx1 with the voltage-sensor toxin guangxitoxin (GxTx-1E). Our results show that both types of tarantula toxins interact with membranes, but that voltage-sensor toxins partition deeper into the bilayer. In addition, our results suggest that tarantula toxins have evolved a similar concave surface for clamping onto α-helices that is effective in aqueous or lipidic physical environments.
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Affiliation(s)
- Kanchan Gupta
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Maryam Zamanian
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Chanhyung Bae
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Mirela Milescu
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
- Biology Division, University of Missouri, Columbia, United States
| | - Dmitriy Krepkiy
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Drew C Tilley
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Jon T Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, United States
| | - Jae Il Kim
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Kenton J Swartz
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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Structural interactions of a voltage sensor toxin with lipid membranes. Proc Natl Acad Sci U S A 2014; 111:E5463-70. [PMID: 25453087 DOI: 10.1073/pnas.1415324111] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein toxins from tarantula venom alter the activity of diverse ion channel proteins, including voltage, stretch, and ligand-activated cation channels. Although tarantula toxins have been shown to partition into membranes, and the membrane is thought to play an important role in their activity, the structural interactions between these toxins and lipid membranes are poorly understood. Here, we use solid-state NMR and neutron diffraction to investigate the interactions between a voltage sensor toxin (VSTx1) and lipid membranes, with the goal of localizing the toxin in the membrane and determining its influence on membrane structure. Our results demonstrate that VSTx1 localizes to the headgroup region of lipid membranes and produces a thinning of the bilayer. The toxin orients such that many basic residues are in the aqueous phase, all three Trp residues adopt interfacial positions, and several hydrophobic residues are within the membrane interior. One remarkable feature of this preferred orientation is that the surface of the toxin that mediates binding to voltage sensors is ideally positioned within the lipid bilayer to favor complex formation between the toxin and the voltage sensor.
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Abstract
SNX-482, a peptide toxin isolated from tarantula venom, has become widely used as an inhibitor of Cav2.3 voltage-gated calcium channels. Unexpectedly, we found that SNX-482 dramatically reduced the A-type potassium current in acutely dissociated dopamine neurons from mouse substantia nigra pars compacta. The inhibition persisted when calcium was replaced by cobalt, showing that it was not secondary to a reduction of calcium influx. Currents from cloned Kv4.3 channels expressed in HEK-293 cells were inhibited by SNX-482 with an IC50 of <3 nM, revealing substantially greater potency than for SNX-482 inhibition of Cav2.3 channels (IC50 20-60 nM). At sub-saturating concentrations, SNX-482 produced a depolarizing shift in the voltage dependence of activation of Kv4.3 channels and slowed activation kinetics. Similar effects were seen on gating of cloned Kv4.2 channels, but the inhibition was less pronounced and required higher toxin concentrations. These results reveal SNX-482 as the most potent inhibitor of Kv4.3 channels yet identified. Because of the effects on both Kv4.3 and Kv4.2 channels, caution is needed when interpreting the effects of SNX-482 on cells and circuits where these channels are present.
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Yunoki T, Takimoto K, Kita K, Funahashi Y, Takahashi R, Matsuyoshi H, Naito S, Yoshimura N. Differential contribution of Kv4-containing channels to A-type, voltage-gated potassium currents in somatic and visceral dorsal root ganglion neurons. J Neurophysiol 2014; 112:2492-504. [PMID: 25143545 DOI: 10.1152/jn.00054.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Little is known about electrophysiological differences of A-type transient K(+) (KA) currents in nociceptive afferent neurons that innervate somatic and visceral tissues. Staining with isolectin B4 (IB4)-FITC classifies L6-S1 dorsal root ganglion (DRG) neurons into three populations with distinct staining intensities: negative to weak, moderate, and intense fluorescence signals. All IB4 intensely stained cells are negative for a fluorescent dye, Fast Blue (FB), injected into the bladder wall, whereas a fraction of somatic neurons labeled by FB, injected to the external urethral dermis, is intensely stained with IB4. In whole-cell, patch-clamp recordings, phrixotoxin 2 (PaTx2), a voltage-gated K(+) (Kv)4 channel blocker, exhibits voltage-independent inhibition of the KA current in IB4 intensely stained cells but not the one in bladder-innervating cells. The toxin also shows voltage-independent inhibition of heterologously expressed Kv4.1 current, whereas its inhibition of Kv4.2 and Kv4.3 currents is voltage dependent. The swapping of four amino acids at the carboxyl portion of the S3 region between Kv4.1 and Kv4.2 transfers this characteristic. RT-PCRs detected Kv4.1 and the long isoform of Kv4.3 mRNAs without significant Kv4.2 mRNA in L6-S1 DRGs. Kv4.1 and Kv4.3 mRNA levels were higher in laser-captured, IB4-stained neurons than in bladder afferent neurons. These results indicate that PaTx2 acts differently on channels in the Kv4 family and that Kv4.1 and possibly Kv4.3 subunits functionally participate in the formation of KA channels in a subpopulation of somatic C-fiber neurons but not in visceral C-fiber neurons innervating the bladder.
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Affiliation(s)
- Takakazu Yunoki
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Koichi Takimoto
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania; Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Japan
| | - Kaori Kita
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania
| | - Yasuhito Funahashi
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ryosuke Takahashi
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Hiroko Matsuyoshi
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Seiji Naito
- Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Naoki Yoshimura
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania;
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Molecular determinants of Hv1 proton channel inhibition by guanidine derivatives. Proc Natl Acad Sci U S A 2014; 111:9971-6. [PMID: 24912149 DOI: 10.1073/pnas.1324012111] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The voltage-gated proton channel Hv1 plays important roles in proton extrusion, pH homeostasis, and production of reactive oxygen species in a variety of cell types. Excessive Hv1 activity increases proliferation and invasiveness in cancer cells and worsens brain damage in ischemic stroke. The channel is composed of two subunits, each containing a proton-permeable voltage-sensing domain (VSD) and lacking the pore domain typical of other voltage-gated ion channels. We have previously shown that the compound 2-guanidinobenzimidazole (2GBI) inhibits Hv1 proton conduction by binding to the VSD from its intracellular side. Here, we examine the binding affinities of a series of 2GBI derivatives on human Hv1 channels mutated at positions located in the core of the VSD and apply mutant cycle analysis to determine how the inhibitor interacts with the channel. We identify four Hv1 residues involved in the binding: aspartate 112, phenylalanine 150, serine 181, and arginine 211. 2GBI appears to be oriented in the binding site with its benzo ring pointing to F150, its imidazole ring inserted between residue D112 and residues S181 and R211, and the guanidine group positioned in the proximity of R211. We also identify a modified version of 2GBI that is able to reach the binding site on Hv1 from the extracellular side of the membrane. Understanding how compounds like 2GBI interact with the Hv1 channel is an important step to the development of pharmacological treatments for diseases caused by Hv1 hyperactivity.
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Sesti F, Wu X, Liu S. Oxidation of KCNB1 K(+) channels in central nervous system and beyond. World J Biol Chem 2014; 5:85-92. [PMID: 24921000 PMCID: PMC4050120 DOI: 10.4331/wjbc.v5.i2.85] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/26/2014] [Accepted: 03/03/2014] [Indexed: 02/05/2023] Open
Abstract
KCNB1, a voltage-gated potassium (K(+)) channel that conducts a major delayed rectifier current in the brain, pancreas and cardiovascular system is a key player in apoptotic programs associated with oxidative stress. As a result, this protein represents a bona fide drug target for limiting the toxic effects of oxygen radicals. Until recently the consensus view was that reactive oxygen species trigger a pro-apoptotic surge in KCNB1 current via phosphorylation and SNARE-dependent incorporation of KCNB1 channels into the plasma membrane. However, new evidence shows that KCNB1 can be modified by oxidants and that oxidized KCNB1 channels can directly activate pro-apoptotic signaling pathways. Hence, a more articulated picture of the pro-apoptotic role of KCNB1 is emerging in which the protein induces cell's death through distinct molecular mechanisms and activation of multiple pathways. In this review article we discuss the diverse functional, toxic and protective roles that KCNB1 channels play in the major organs where they are expressed.
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Kv2 channel regulation of action potential repolarization and firing patterns in superior cervical ganglion neurons and hippocampal CA1 pyramidal neurons. J Neurosci 2014; 34:4991-5002. [PMID: 24695716 DOI: 10.1523/jneurosci.1925-13.2014] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Kv2 family "delayed-rectifier" potassium channels are widely expressed in mammalian neurons. Kv2 channels activate relatively slowly and their contribution to action potential repolarization under physiological conditions has been unclear. We explored the function of Kv2 channels using a Kv2-selective blocker, Guangxitoxin-1E (GxTX-1E). Using acutely isolated neurons, mixed voltage-clamp and current-clamp experiments were done at 37°C to study the physiological kinetics of channel gating and action potentials. In both rat superior cervical ganglion (SCG) neurons and mouse hippocampal CA1 pyramidal neurons, 100 nm GxTX-1E produced near-saturating block of a component of current typically constituting ∼60-80% of the total delayed-rectifier current. GxTX-1E also reduced A-type potassium current (IA), but much more weakly. In SCG neurons, 100 nm GxTX-1E broadened spikes and voltage clamp experiments using action potential waveforms showed that Kv2 channels carry ∼55% of the total outward current during action potential repolarization despite activating relatively late in the spike. In CA1 neurons, 100 nm GxTX-1E broadened spikes evoked from -70 mV, but not -80 mV, likely reflecting a greater role of Kv2 when other potassium channels were partially inactivated at -70 mV. In both CA1 and SCG neurons, inhibition of Kv2 channels produced dramatic depolarization of interspike voltages during repetitive firing. In CA1 neurons and some SCG neurons, this was associated with increased initial firing frequency. In all neurons, inhibition of Kv2 channels depressed maintained firing because neurons entered depolarization block more readily. Therefore, Kv2 channels can either decrease or increase neuronal excitability depending on the time scale of excitation.
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Detection and identification of huwentoxin-IV interacting proteins by biotin-avidin chemistry combined with mass spectrometry. J Venom Anim Toxins Incl Trop Dis 2014; 20:18. [PMID: 24803923 PMCID: PMC4011514 DOI: 10.1186/1678-9199-20-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 04/17/2014] [Indexed: 11/10/2022] Open
Abstract
Background Numerous spider toxins are of interest as tools for neurophysiological research or as lead molecules for the development of pharmaceuticals and insecticides. Direct detection and identification of the interacting proteins of a spider toxin are helpful for its action-mechanism analysis and practical application. The present study employed a combinative strategy for the analysis of interacting proteins of huwentoxin-IV (HWTX-IV), a peptidic neurotoxin from the venom of the spider Selenocosmia huwena. Results HWTX-IV was first lightly labeled with biotin under the optimized mild experimental conditions and the toxin labeled with a single biotin group (monobiotinylated HWTX-IV) was demonstrated by electrophysiological experiments to retain its original bioactivity and was used in combination with far-western blotting to detect its interacting proteins. Comparative experiments indicated that some membrane proteins from rat neuromuscular junction preparations bind to monobiotinylated HWTX-IV after being transferred onto a PVDF membrane from the SDS-gel. With capillary high performance liquid chromatography-tandem mass spectrometry, several membrane proteins with which HWTX-IV potentially interacted were identified from the preparations and then bioinformatically analyzed. Conclusions This work has provided not only a new insight into the action mechanism of HWTX-IV but also a reference technology for the relevant researches.
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Klint JK, Berecki G, Durek T, Mobli M, Knapp O, King GF, Adams DJ, Alewood PF, Rash LD. Isolation, synthesis and characterization of ω-TRTX-Cc1a, a novel tarantula venom peptide that selectively targets L-type Cav channels. Biochem Pharmacol 2014; 89:276-86. [PMID: 24561180 DOI: 10.1016/j.bcp.2014.02.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/10/2014] [Accepted: 02/10/2014] [Indexed: 12/16/2022]
Abstract
Spider venoms are replete with peptidic ion channel modulators, often with novel subtype selectivity, making them a rich source of pharmacological tools and drug leads. In a search for subtype-selective blockers of voltage-gated calcium (CaV) channels, we isolated and characterized a novel 39-residue peptide, ω-TRTX-Cc1a (Cc1a), from the venom of the tarantula Citharischius crawshayi (now Pelinobius muticus). Cc1a is 67% identical to the spider toxin ω-TRTX-Hg1a, an inhibitor of CaV2.3 channels. We assembled Cc1a using a combination of Boc solid-phase peptide synthesis and native chemical ligation. Oxidative folding yielded two stable, slowly interconverting isomers. Cc1a preferentially inhibited Ba(2+) currents (IBa) mediated by L-type (CaV1.2 and CaV1.3) CaV channels heterologously expressed in Xenopus oocytes, with half-maximal inhibitory concentration (IC50) values of 825nM and 2.24μM, respectively. In rat dorsal root ganglion neurons, Cc1a inhibited IBa mediated by high voltage-activated CaV channels but did not affect low voltage-activated T-type CaV channels. Cc1a exhibited weak activity at NaV1.5 and NaV1.7 voltage-gated sodium (NaV) channels stably expressed in mammalian HEK or CHO cells, respectively. Experiments with modified Cc1a peptides, truncated at the N-terminus (ΔG1-E5) or C-terminus (ΔW35-V39), demonstrated that the N- and C-termini are important for voltage-gated ion channel modulation. We conclude that Cc1a represents a novel pharmacological tool for probing the structure and function of L-type CaV channels.
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Affiliation(s)
- Julie K Klint
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia.
| | - Géza Berecki
- Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia.
| | - Thomas Durek
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia.
| | - Mehdi Mobli
- Centre for Advanced Imaging, The University of Queensland, St Lucia, QLD 4072, Australia.
| | - Oliver Knapp
- Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia.
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia.
| | - David J Adams
- Health Innovations Research Institute, RMIT University, Bundoora, VIC 3083, Australia.
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia.
| | - Lachlan D Rash
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia.
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Chen M, Li J, Zhang F, Liu Z. Isolation and characterization of SsmTx-I, a Specific Kv2.1 blocker from the venom of the centipede Scolopendra Subspinipes Mutilans
L. Koch. J Pept Sci 2014; 20:159-64. [DOI: 10.1002/psc.2588] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/20/2013] [Accepted: 10/21/2013] [Indexed: 01/24/2023]
Affiliation(s)
- Minzhi Chen
- College of Life Science; Hunan Normal University; Changsha 410081 China
| | - Jing Li
- College of Life Science; Hunan Normal University; Changsha 410081 China
| | - Fan Zhang
- College of Life Science; Hunan Normal University; Changsha 410081 China
| | - Zhonghua Liu
- College of Life Science; Hunan Normal University; Changsha 410081 China
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