1
|
Zhou J, Wang W, Liu D, Xu S, Wang X, Zhang X, Wang X, Li Y, Sheng L, Wang X, Xu B. Discovery of 2-Ethoxy-5-isobutyramido- N-1-substituted Benzamide Derivatives as Selective Kv2.1 Inhibitors with In Vivo Neuroprotective Effects. J Med Chem 2024; 67:213-233. [PMID: 38150670 DOI: 10.1021/acs.jmedchem.3c01245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Kv2.1 is involved in regulating neuronal excitability and neuronal cell apoptosis, and inhibiting Kv2.1 is a potential strategy to prevent cell death and achieve neuroprotection in ischemic stroke. In this work, a series of novel benzamide derivatives were designed and synthesized as Kv2.1 inhibitors, and extensive structure-activity relationships led to highly potent and selective Kv2.1 inhibitors having IC50 values of 10-8 M. Among them, compound 80 (IC50 = 0.07 μM, selectivity >130 fold over other K+, Na+, and Ca2+ ion channels) was able to decrease the apoptosis of HEK293/Kv2.1 cells induced by H2O2. Furthermore, its anti-ischemic efficacy was demonstrated as it markedly reduced the infarct volume in MCAO rat model. Additionally, compound 80 possessed appropriate plasma PK parameters. It could serve as a probe to investigate Kv2.1 pathological functions and deserved to be further explored.
Collapse
Affiliation(s)
- Jie Zhou
- Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Weiping Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Dong Liu
- Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Shaofeng Xu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xue Wang
- Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xinyuan Zhang
- Information Center, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xiaoyu Wang
- Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Yan Li
- Beijing Key Laboratory of Non-Clinical Drug Metabolism and PK/PD Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Li Sheng
- Beijing Key Laboratory of Non-Clinical Drug Metabolism and PK/PD Study, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xiaoliang Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Bailing Xu
- Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| |
Collapse
|
2
|
Peng S, Chen M, Xiao Z, Xiao X, Luo S, Liang S, Zhou X, Liu Z. A Novel Spider Toxin Inhibits Fast Inactivation of the Na v1.9 Channel by Binding to Domain III and Domain IV Voltage Sensors. Front Pharmacol 2021; 12:778534. [PMID: 34938190 PMCID: PMC8685421 DOI: 10.3389/fphar.2021.778534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/05/2021] [Indexed: 11/13/2022] Open
Abstract
Venomous animals have evolved to produce peptide toxins that modulate the activity of voltage-gated sodium (Nav) channels. These specific modulators are powerful probes for investigating the structural and functional features of Nav channels. Here, we report the isolation and characterization of δ-theraphotoxin-Gr4b (Gr4b), a novel peptide toxin from the venom of the spider Grammostola rosea. Gr4b contains 37-amino acid residues with six cysteines forming three disulfide bonds. Patch-clamp analysis confirmed that Gr4b markedly slows the fast inactivation of Nav1.9 and inhibits the currents of Nav1.4 and Nav1.7, but does not affect Nav1.8. It was also found that Gr4b significantly shifts the steady-state activation and inactivation curves of Nav1.9 to the depolarization direction and increases the window current, which is consistent with the change in the ramp current. Furthermore, analysis of Nav1.9/Nav1.8 chimeric channels revealed that Gr4b preferentially binds to the voltage-sensor of domain III (DIII VSD) and has additional interactions with the DIV VSD. The site-directed mutagenesis analysis indicated that N1139 and L1143 in DIII S3-S4 linker participate in toxin binding. In sum, this study reports a novel spider peptide toxin that may slow the fast inactivation of Nav1.9 by binding to the new neurotoxin receptor site-DIII VSD. Taken together, these findings provide insight into the functional role of the Nav channel DIII VSD in fast inactivation and activation.
Collapse
Affiliation(s)
- Shuijiao Peng
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Minzhi Chen
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Zhen Xiao
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Xin Xiao
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Sen Luo
- 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
| | - Xi Zhou
- 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
| |
Collapse
|
3
|
Pałasz A, Krzystanek M. Spider Neurotoxins as Modulators of NMDA Receptor Signaling. Neuromolecular Med 2021; 24:250-256. [PMID: 34562203 PMCID: PMC9402494 DOI: 10.1007/s12017-021-08692-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/14/2021] [Indexed: 11/26/2022]
Abstract
Molecules that selectively act on N-methyl-D-aspartate (NMDA) receptors may have a multidirectional effect by modulating the activity of NMDARs, affecting their active sites as well as by changing the composition of their subunits. The results of the clinical trials conducted so far in mood disorders and schizophrenia indicate that such agents may become new effective drugs for the treatment of these diseases. Number of spider neurotoxins e.g. ctenitoxins extracted from Phoneutria sp. venom act as potent and selective NMDAR blockers that do not disturb cortical and hippocampal glutamate signaling, LTP generation and synaptic neurochemistry. Possibly this intriguing kind of promising neuroregulatory peptides and polyamines can be clinically applicable in a wide spectrum of neuropsychiatric disorders, including epilepsy, neurotrauma and ischemic injuries. These novel medications can potentially be helpful in the future treatment of stroke and several neurodegenerative diseases.
Collapse
Affiliation(s)
- Artur Pałasz
- Department of Histology, Faculty of Medical Sciences, Medical University of Silesia, ul. Medyków 18, 40-752, Katowice, Poland.
| | - Marek Krzystanek
- Department of Psychiatry and Psychotherapy, Clinic of Psychiatric Rehabilitation, Faculty of Medical Sciences in Katowice, Medical University of Silesia, ul. Ziolowa 45/47, 40-635, Katowice, Poland
| |
Collapse
|
4
|
Chao RY, Cheng CH, Wu SN, Chen PC. Defective trafficking of Kv2.1 channels in MPTP-induced nigrostriatal degeneration. J Neurochem 2018; 144:483-497. [PMID: 29265365 DOI: 10.1111/jnc.14282] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/13/2017] [Accepted: 12/07/2017] [Indexed: 12/19/2022]
Abstract
Intracellular protein trafficking is tightly regulated, and improper trafficking might be the fundamental provocateur for human diseases including neurodegeneration. In neurons, protein trafficking to and from the plasma membrane affects synaptic plasticity. Voltage-gated potassium channel 2.1 (Kv2.1) is a predominant delayed rectifier potassium (K+ ) current, and electrical activity patterns of dopamine (DA) neurons within the substantia nigra are generated and modulated by the orchestrated function of different ion channels. The pathological hallmark of Parkinson's disease (PD) is the progressive loss of these DA neurons, resulting in the degeneration of striatal dopaminergic terminals. However, whether trafficking of Kv2.1 channels contributes to PD remains unclear. In this study, we demonstrated that MPTP/MPP+ increases the surface expression of the Kv2.1 channel and causes nigrostriatal degeneration by using a subchronic MPTP mouse model. The inhibition of the Kv2.1 channel by using a specific blocker, guangxitoxin-1E, protected nigrostriatal projections against MPTP/MPP+ insult and thus facilitated the recovery of motor coordination. These findings highlight the importance of trafficking of Kv2.1 channels in the pathogenesis of PD.
Collapse
Affiliation(s)
- Ru-Yi Chao
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chia-Hui Cheng
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Pei-Chun Chen
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| |
Collapse
|
5
|
Hung A, Kuyucak S, Schroeder CI, Kaas Q. Modelling the interactions between animal venom peptides and membrane proteins. Neuropharmacology 2017; 127:20-31. [PMID: 28778835 DOI: 10.1016/j.neuropharm.2017.07.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/18/2017] [Accepted: 07/31/2017] [Indexed: 12/19/2022]
Abstract
The active components of animal venoms are mostly peptide toxins, which typically target ion channels and receptors of both the central and peripheral nervous system, interfering with action potential conduction and/or synaptic transmission. The high degree of sequence conservation of their molecular targets makes a range of these toxins active at human receptors. The high selectivity and potency displayed by some of these toxins have prompted their use as pharmacological tools as well as drugs or drug leads. Molecular modelling has played an essential role in increasing our molecular-level understanding of the activity and specificity of animal toxins, as well as engineering them for biotechnological and pharmaceutical applications. This review focuses on the biological insights gained from computational and experimental studies of animal venom toxins interacting with membranes and ion channels. A host of recent X-ray crystallography and electron-microscopy structures of the toxin targets has contributed to a dramatic increase in the accuracy of the molecular models of toxin binding modes greatly advancing this exciting field of study. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
Collapse
Affiliation(s)
- Andrew Hung
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Christina I Schroeder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane 4072, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane 4072, Australia.
| |
Collapse
|
6
|
Lee CH, Huang PT, Liou HH, Lin MY, Lou KL, Chen CY. Non-basic amino acids in the ROMK1 channels via an appropriate distance modulate PIP2 regulated pHi-gating. Biochem Biophys Res Commun 2016; 473:303-310. [PMID: 27016482 DOI: 10.1016/j.bbrc.2016.03.100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 03/21/2016] [Indexed: 12/11/2022]
Abstract
The ROMK1 (Kir1.1) channel activity is predominantly regulated by intracellular pH (pHi) and phosphatidylinositol 4,5-bisphosphate (PIP2). Although several residues were reported to be involved in the regulation of pHi associated with PIP2 interaction, the detailed molecular mechanism remains unclear. We perform experiments in ROMK1 pHi-gating with electrophysiology combined with mutational and structural analysis. In the present study, non basic residues of C-terminal region (S219, N215, I192, L216 and L220) in ROMK1 channels have been found to mediate channel-PIP2 interaction and pHi gating. Further, our structural results show these residues with an appropriate distance to interact with membrane PIP2. Meanwhile, a cluster of basic residues (R188, R217 and K218), which was previously discovered regarding the interaction with PIP2, exists in this appropriate distance to discriminate the regulation of channel-PIP2 interaction and pHi-gating. This appropriate distance can be observed with high conservation in the Kir channel family. Our results provide insight that an appropriate distance cooperates with the electrostatics interaction of channel-PIP2 to regulate pHi-gating.
Collapse
Affiliation(s)
- Chien-Hsing Lee
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan; Department of Nursing, Min-Hwei Junior College of Health Care Management, Tainan, 73658, Taiwan
| | - Po-Tsang Huang
- Institutes of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan; Graduate Institutes of Oral Biology, Medical College, National Taiwan University, Taipei, 10048, Taiwan
| | - Horng-Huei Liou
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan; Divisions of Neurology, National Taiwan University Hospital, Taipei, 10002, Taiwan
| | - Mei-Ying Lin
- Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung, 80708, Taiwan
| | - Kuo-Long Lou
- Institutes of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan; Graduate Institutes of Oral Biology, Medical College, National Taiwan University, Taipei, 10048, Taiwan; NTU-DRCP Lectures and Core for Membrane Proteins, Center for Biotechnology, National Taiwan University, Taipei, 10672, Taiwan.
| | - Chung-Yi Chen
- School of Medical and Health Sciences, Fooyin University, No.151, Jinxue Rd., Daliao Dist., Kaohsiung City, 83102, Taiwan.
| |
Collapse
|
7
|
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.
Collapse
|
8
|
Kim H, Yang I, Ryu SY, Won DH, Giri AG, Wang W, Choi H, Chin J, Hahn D, Kim E, Han C, Lee J, Nam SJ, Ho WK, Kang H. Acredinones A and B, voltage-dependent potassium channel inhibitors from the sponge-derived fungus Acremonium sp. F9A015. JOURNAL OF NATURAL PRODUCTS 2015; 78:363-367. [PMID: 25689430 DOI: 10.1021/np5007586] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Two new benzophenones, acredinones A (1) and B (2), were isolated from a marine-sponge-associated Acremonium sp. fungus. Their chemical structures were elucidated on the interpretation of spectroscopic data. The structure of 1 was confirmed by palladium-catalyzed hydrogenation, followed by spectroscopic data analysis. Acredinones A (1) and B (2) inhibited the outward K(+) currents of the insulin secreting cell line INS-1 with IC50 values of 0.59 and 1.0 μM, respectively.
Collapse
Affiliation(s)
- Hiyoung Kim
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Inho Yang
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Shin-Young Ryu
- ‡National Research Laboratory for Cell Physiology and Department of Physiology, Seoul National University College of Medicine, 28 Yonkeun-Dong, Chongno-Ku, Seoul 110-799, Korea
| | - Dong Hwan Won
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Awadut G Giri
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Weihong Wang
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Hyukjae Choi
- §College of Pharmacy, Yeungnam University, 214-1 Dae-dong, Gyeongsan 712-749, Korea
| | - Jungwook Chin
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Dongyup Hahn
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Eunhee Kim
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Chulkyeong Han
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Jihye Lee
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
| | - Sang-Jip Nam
- ⊥Department of Chemistry and Nano Science, Global Top 5 Program, Ewha Womans University, Seoul 120-750, Korea
| | - Won-Kyung Ho
- ‡National Research Laboratory for Cell Physiology and Department of Physiology, Seoul National University College of Medicine, 28 Yonkeun-Dong, Chongno-Ku, Seoul 110-799, Korea
| | - Heonjoong Kang
- †Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Sciences, Seoul National University, NS-80, Seoul 151-747, Korea
- ∥Research Institute of Oceanography, Seoul National University, NS-80, Seoul 151-747, Korea
| |
Collapse
|
9
|
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.
Collapse
|
10
|
Chen R, Chung SH. Complex structures between the N-type calcium channel (CaV2.2) and ω-conotoxin GVIA predicted via molecular dynamics. Biochemistry 2013; 52:3765-72. [PMID: 23651160 DOI: 10.1021/bi4003327] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The N-type voltage-gated Ca(2+) channel CaV2.2 is one of the important targets for pain management. ω-Conotoxins isolated from venoms of cone snails, which specifically inhibit CaV2.2, are promising scaffolds for novel analgesics. The inhibitory action of ω-conotoxins on CaV2.2 has been examined experimentally, but the modes of binding of the toxins to this and other related subfamilies of Ca(2+) channels are not understood in detail. Here molecular dynamics simulations are used to construct models of ω-conotoxin GVIA in complex with a homology model of the pore domain of CaV2.2. Three different binding modes in which the side chain of Lys2, Arg17, or Lys24 from the toxin protrudes into the selectivity filter of CaV2.2 are considered. In all the modes, the toxin forms a salt bridge with an aspartate residue of subunit II just above the EEEE ring of the selectivity filter. Using the umbrella sampling technique and potential of mean force calculations, the half-maximal inhibitory concentration (IC50) values are calculated to be 1.5 and 0.7 nM for the modes in which Lys2 and Arg17 occlude the ion conduction pathway, respectively. Both IC50 values compare favorably with the values of 0.04-1.0 nM determined experimentally. The similar IC50 values calculated for the different binding modes demonstrate that GVIA can inhibit CaV2.2 with alternative binding modes. Such a multiple-binding mode mechanism may be common for ω-conotoxins.
Collapse
Affiliation(s)
- Rong Chen
- Research School of Biology, Australian National University , Canberra, ACT 0200, Australia
| | | |
Collapse
|