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Kumari M, Khatoon N, Sharma R, Adusumilli S, Auerbach A, Kashyap HK, Nayak TK. Mechanism of hydrophobic gating in the acetylcholine receptor channel pore. J Gen Physiol 2024; 156:e202213189. [PMID: 38153395 PMCID: PMC10757554 DOI: 10.1085/jgp.202213189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/16/2023] [Accepted: 12/06/2023] [Indexed: 12/29/2023] Open
Abstract
Neuromuscular acetylcholine receptors (AChRs) are hetero-pentameric, ligand-gated ion channels. The binding of the neurotransmitter acetylcholine (ACh) to two target sites promotes a global conformational change of the receptor that opens the channel and allows ion conduction through the channel pore. Here, by measuring free-energy changes from single-channel current recordings and using molecular dynamics simulations, we elucidate how a constricted hydrophobic region acts as a "gate" to regulate the channel opening in the pore of AChRs. Mutations of gate residues, including those implicated in congenital myasthenia syndrome, lower the permeation barrier of the channel substantially and increase the unliganded gating equilibrium constant (constitutive channel openings). Correlations between hydrophobicity and the observed free-energy changes, supported by calculations of water densities in the wild-type versus mutant channel pores, provide evidence for hydrophobic wetting-dewetting transition at the gate. The analysis of a coupled interaction network provides insight into the molecular mechanism of closed- versus open-state conformational changes at the gate. Studies of the transition state by "phi"(φ)-value analysis indicate that agonist binding serves to stabilize both the transition and the open state. Intersubunit interaction energy measurements and molecular dynamics simulations suggest that channel opening involves tilting of the pore-lining M2 helices, asymmetric outward rotation of amino acid side chains, and wetting transition of the gate region that lowers the barrier to ion permeation and stabilizes the channel open conformation. Our work provides new insight into the hydrophobic gate opening and shows why the gate mutations result in constitutive AChR channel activity.
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Affiliation(s)
- Monika Kumari
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Nadira Khatoon
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Rachita Sharma
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Sushanth Adusumilli
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Anthony Auerbach
- Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
| | - Tapan K. Nayak
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India
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2
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Kuzmenkov AI, Gigolaev AM, Pinheiro-Junior EL, Peigneur S, Tytgat J, Vassilevski AA. Methionine-isoleucine dichotomy at a key position in scorpion toxins inhibiting voltage-gated potassium channels. Toxicon 2023; 231:107181. [PMID: 37301298 DOI: 10.1016/j.toxicon.2023.107181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/06/2023] [Accepted: 06/06/2023] [Indexed: 06/12/2023]
Abstract
Previous studies have identified some key amino acid residues in scorpion toxins blocking potassium channels. In particular, the most numerous toxins belonging to the α-KTx family and affecting voltage-gated potassium channels (KV) present a conserved K-C-X-N motif in the C-terminal half of their sequence. Here, we show that the X position of this motif is almost always occupied by either methionine or isoleucine. We compare the activity of three pairs of peptides that differ just by this residue on a panel of KV1 channels and find that toxins bearing methionine affect preferentially KV1.1 and 1.6 isoforms. The refined K-C-M/I-N motif stands out as the principal structural element of α-KTx conferring high affinity and selectivity to KV channels.
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Affiliation(s)
- Alexey I Kuzmenkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
| | - Andrei M Gigolaev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | | | - Steve Peigneur
- Toxicology and Pharmacology, KU Leuven, Leuven, 3000, Belgium
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Leuven, 3000, Belgium
| | - Alexander A Vassilevski
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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3
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Kimball IH, Nguyen PT, Olivera BM, Sack JT, Yarov-Yarovoy V. Molecular determinants of μ-conotoxin KIIIA interaction with the human voltage-gated sodium channel Na V1.7. Front Pharmacol 2023; 14:1156855. [PMID: 37007002 PMCID: PMC10060530 DOI: 10.3389/fphar.2023.1156855] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 03/03/2023] [Indexed: 03/18/2023] Open
Abstract
The voltage-gated sodium (NaV) channel subtype NaV1.7 plays a critical role in pain signaling, making it an important drug target. Here we studied the molecular interactions between μ-Conotoxin KIIIA (KIIIA) and the human NaV1.7 channel (hNaV1.7). We developed a structural model of hNaV1.7 using Rosetta computational modeling and performed in silico docking of KIIIA using RosettaDock to predict residues forming specific pairwise contacts between KIIIA and hNaV1.7. We experimentally validated these contacts using mutant cycle analysis. Comparison between our KIIIA-hNaV1.7 model and the cryo-EM structure of KIIIA-hNaV1.2 revealed key similarities and differences between NaV channel subtypes with potential implications for the molecular mechanism of toxin block. The accuracy of our integrative approach, combining structural data with computational modeling, experimental validation, and molecular dynamics simulations, suggests that Rosetta structural predictions will be useful for rational design of novel biologics targeting specific NaV channels.
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Affiliation(s)
- Ian H. Kimball
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
| | - Phuong T. Nguyen
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
| | | | - Jon T. Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA, United States
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA, United States
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4
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Structure-guided peptide engineering of a positive allosteric modulator targeting the outer pore of TRPV1 for long-lasting analgesia. Nat Commun 2023; 14:4. [PMID: 36596769 PMCID: PMC9810691 DOI: 10.1038/s41467-022-34817-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 11/08/2022] [Indexed: 01/05/2023] Open
Abstract
Transient receptor potential vanilloid 1 (TRPV1) ion channel is a classic analgesic target, but antagonists of TRPV1 failed in clinical trials due to their side effects like hyperthermia. Here we rationally engineer a peptide s-RhTx as a positive allosteric modulator (PAM) of TRPV1. Patch-clamp recordings demonstrate s-RhTx selectively potentiated TRPV1 activation. s-RhTx also slows down capsaicin-induced desensitization of TRPV1 in the presence of calcium to cause more calcium influx in TRPV1-expressing cells. In addition, our thermodynamic mutant cycle analysis shows that E652 in TRPV1 outer pore specifically interacts with R12 and K22 in s-RhTx. Furthermore, we demonstrate in vivo that s-RhTx exhibits long-lasting analgesic effects in noxious heat hyperalgesia and CFA-induced chronic inflammatory pain by promoting the reversible degeneration of intra-epidermal nerve fiber (IENF) expressing TRPV1 channels in mice, while their body temperature remains unaffected. Our results suggest s-RhTx is an analgesic agent as a PAM of TRPV1.
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Kelkar S, Nailwal N, Bhatia NY, Doshi G, Sathaye S, Godad AP. An Update On Proficiency of Voltage-gated Ion Channel Blockers in the Treatment of Inflammation-associated Diseases. Curr Drug Targets 2022; 23:1290-1303. [PMID: 35996239 DOI: 10.2174/1389450123666220819141827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/24/2022] [Accepted: 06/21/2022] [Indexed: 01/25/2023]
Abstract
Inflammation is the body's mechanism to trigger the immune system, thereby preventing bacteria and viruses from manifesting their toxic effect. Inflammation plays a vital role in regulating inflammatory mediator levels to initiate the wound healing process depending on the nature of the stimuli. This process occurs due to chemical release from white blood cells by elevating blood flow to the site of action, leading to redness and increased body temperature. Currently, there are numerous Non-steroidal anti-inflammatory drugs (NSAIDs) available, but these drugs are reported with adverse effects such as gastric bleeding, progressive kidney damage, and increased risk of heart attacks when prolonged use. For such instances, alternative options need to be adopted. The introduction of voltage-gated ion channel blockers can be a substantial alternative to mask the side effects of these currently available drugs. Chronic inflammatory disorders such as rheumatoid and osteoarthritis, cancer and migraine, etc., can cause dreadful pain, which is often debilitating for the patient. The underlying mechanism for both acute and chronic inflammation involves various complex receptors, different types of cells, receptors, and proteins. The working of voltage-gated sodium and calcium channels is closely linked to both inflammatory and neuropathic pain. Certain drugs such as carbamazepine and gabapentin, which are ion channel blockers, have greater pharmacotherapeutic activity for sodium and calcium channel blockers for the treatment of chronic inflammatory pain states. This review intends to provide brief information on the mechanism of action, latest clinical trials, and applications of these blockers in treating inflammatory conditions.
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Affiliation(s)
- Siddesh Kelkar
- MET Institute of Pharmacy, Bhujbal Knowledge City, Reclamation, Bandra West, Mumbai, Maharashtra 400050, India
| | - Namrata Nailwal
- SVKM's Dr. Bhanuben Nanavati College of Pharmacy, Mithibai College Campus, Vaikunthlal Mehta Rd, Vile Parle West, Mumbai, Maharashtra 400056, India
| | - Nirav Yogesh Bhatia
- SVKM's Dr. Bhanuben Nanavati College of Pharmacy, Mithibai College Campus, Vaikunthlal Mehta Rd, Vile Parle West, Mumbai, Maharashtra 400056, India
| | - Gaurav Doshi
- SVKM's Dr. Bhanuben Nanavati College of Pharmacy, Mithibai College Campus, Vaikunthlal Mehta Rd, Vile Parle West, Mumbai, Maharashtra 400056, India
| | - Sadhana Sathaye
- Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Mumbai, India
| | - Angel Pavalu Godad
- SVKM's Dr. Bhanuben Nanavati College of Pharmacy, Mithibai College Campus, Vaikunthlal Mehta Rd, Vile Parle West, Mumbai, Maharashtra 400056, India.,Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Mumbai, India
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Abbott GW. Kv Channel Ancillary Subunits: Where Do We Go from Here? Physiology (Bethesda) 2022; 37:0. [PMID: 35797055 PMCID: PMC9394777 DOI: 10.1152/physiol.00005.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (Kv) channels each comprise four pore-forming α-subunits that orchestrate essential duties such as voltage sensing and K+ selectivity and conductance. In vivo, however, Kv channels also incorporate regulatory subunits-some Kv channel specific, others more general modifiers of protein folding, trafficking, and function. Understanding all the above is essential for a complete picture of the role of Kv channels in physiology and disease.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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7
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Denisova KR, Orlov NA, Yakimov SA, Kirpichnikov MP, Feofanov AV, Nekrasova OV. Atto488-Agitoxin 2—A Fluorescent Ligand with Increased Selectivity for Kv1.3 Channel Binding Site. Bioengineering (Basel) 2022; 9:bioengineering9070295. [PMID: 35877346 PMCID: PMC9312206 DOI: 10.3390/bioengineering9070295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/29/2022] [Accepted: 06/30/2022] [Indexed: 11/16/2022] Open
Abstract
Fluorescently labeled peptide blockers of ion channels are useful probes in studying the localization and functioning of the channels and in the performance of a search for new channel ligands with bioengineering screening systems. Here, we report on the properties of Atto488-agitoxin 2 (A-AgTx2), a derivative of the Kv1 channel blocker agitoxin 2 (AgTx2), which was N-terminally labeled with Atto 488 fluorophore. The interactions of A-AgTx2 with the outer binding sites of the potassium voltage-gated Kv1.x (x = 1, 3, 6) channels were studied using bioengineered hybrid KcsA–Kv1.x (x = 1, 3, 6) channels. In contrast to AgTx2, A-AgTx2 was shown to lose affinity for the Kv1.1 and Kv1.6 binding sites but to preserve it for the Kv1.3 site. Thus, Atto488 introduces two new functionalities to AgTx2: fluorescence and the selective targeting of the Kv1.3 channel, which is known for its pharmacological significance. In the case of A-AgTx2, fluorescent labeling served as an alternative to site-directed mutagenesis in modulating the pharmacological profile of the channel blocker. Although the affinity of A-AgTx2 for the Kv1.3 binding site was decreased as compared to the unlabeled AgTx2, its dissociation constant value was within a low nanomolar range (4.0 nM). The properties of A-AgTx2 allow one to use it for the search and study of Kv1.3 channel blockers as well as to consider it for the imaging of the Kv1.3 channel in cells and tissues.
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Affiliation(s)
- Kristina R. Denisova
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia; (K.R.D.); (N.A.O.); (M.P.K.)
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (S.A.Y.); (O.V.N.)
| | - Nikita A. Orlov
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia; (K.R.D.); (N.A.O.); (M.P.K.)
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (S.A.Y.); (O.V.N.)
| | - Sergey A. Yakimov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (S.A.Y.); (O.V.N.)
| | - Mikhail P. Kirpichnikov
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia; (K.R.D.); (N.A.O.); (M.P.K.)
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (S.A.Y.); (O.V.N.)
| | - Alexey V. Feofanov
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia; (K.R.D.); (N.A.O.); (M.P.K.)
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (S.A.Y.); (O.V.N.)
- Correspondence:
| | - Oksana V. Nekrasova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia; (S.A.Y.); (O.V.N.)
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8
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Chen X, Xu L, Zhang H, Wen H, Yang F. Differential Activation of TRPM8 by the Stereoisomers of Menthol. Front Pharmacol 2022; 13:898670. [PMID: 35800442 PMCID: PMC9253294 DOI: 10.3389/fphar.2022.898670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 05/09/2022] [Indexed: 11/29/2022] Open
Abstract
The stereoisomers of menthol elicit cooling sensation to various levels. Though the high-resolution three-dimensional structures of the menthol receptor, the transient receptor potential melastatin 8 (TRPM8) ion channels, have been revolved in different states, the menthol-bound state structure is not determined and how the stereoisomers of menthol interact with TRPM8 remains largely elusive. Taking advantage of the identical atom composition but distinct spatial orientation of chemical groups in menthol stereoisomers, we performed thermodynamic mutant cycle analysis (TMCA) with patch-clamp recordings to probe the interaction between these ligands and TRPM8. By comparing (−)-menthol with (+)-neoisomenthol or (+)-neomenthol, we observed that the isopropyl or hydroxyl group in menthol interacts with the S4 or S3 helix in TRPM8, respectively. These interactions were also corroborated in our molecular docking of the stereoisomers, though the predicted structural details in the interactions of these ligands with TRPM8 residues are different. Therefore, we suggest similar molecular mechanisms of TRPM8 activation by the stereoisomers of menthol, while the binding configuration of an individual stereoisomer is varied.
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Affiliation(s)
- Xiaoying Chen
- Department of Biophysics, Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lizhen Xu
- Department of Biophysics, Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Heng Zhang
- Department of Biophysics, Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Han Wen
- DP Technology, Beijing, China
| | - Fan Yang
- Department of Biophysics, Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare, Hangzhou, China
- *Correspondence: Fan Yang,
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Molecular determinants of inhibition of the human proton channel hHv1 by the designer peptide C6 and a bivalent derivative. Proc Natl Acad Sci U S A 2022; 119:e2120750119. [PMID: 35648818 PMCID: PMC9191634 DOI: 10.1073/pnas.2120750119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We designed C6 peptide to address the absence of specific inhibitors of human voltage-gated proton channels (hHv1). Two C6 bind to the two hHv1 voltage sensors at the resting state, inhibiting activation on depolarization. Here, we identify the C6–hHv1 binding interface using tethered-toxin variants and channel mutants, unveil an important role for negatively charged lipids, and present a model of the C6–hHv1 complex. Inspired by nature, we create a peptide with two C6 epitopes (C62) that binds to both channel subunits simultaneously, yielding picomolar affinity and significantly improved inhibition at high potentials. C6 and C62 are peptides designed to regulate hHv1, a channel involved in innate immune-system inflammatory pathophysiology, sperm capacitation, cancer-cell proliferation, and tissue damage in ischemic stroke. The human voltage-gated proton channel (hHv1) is important for control of intracellular pH. We designed C6, a specific peptide inhibitor of hHv1, to evaluate the roles of the channel in sperm capacitation and in the inflammatory immune response of neutrophils [R. Zhao et al., Proc. Natl. Acad. Sci. U.S.A. 115, E11847–E11856 (2018)]. One C6 binds with nanomolar affinity to each of the two S3–S4 voltage-sensor loops in hHv1 in cooperative fashion so that C6-bound channels require greater depolarization to open and do so more slowly. As depolarization drives hHv1 sensors outwardly, C6 affinity decreases, and inhibition is partial. Here, we identified residues essential to C6–hHv1 binding by scanning mutagenesis, five in the hHv1 S3–S4 loops and seven on C6. A structural model of the C6–hHv1 complex was then generated by molecular dynamics simulations and validated by mutant-cycle analysis. Guided by this model, we created a bivalent C6 peptide (C62) that binds simultaneously to both hHv1 subunits and fully inhibits current with picomolar affinity. The results help delineate the structural basis for C6 state-dependent inhibition, support an anionic lipid-mediated binding mechanism, and offer molecular insight into the effectiveness of engineered C6 as a therapeutic agent or lead.
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Dehong X, Wenmei W, Siqin H, Peng Z, Xianchun W, Xiongzhi Z. Effects of JZTX-V on the wild type Kv4.3 Expressed in HEK293T and Molecular Determinants in the Voltage-sensing Domains of Kv4.3 Interacting with JZTX-V. Channels (Austin) 2022; 16:72-83. [PMID: 35378047 PMCID: PMC8986175 DOI: 10.1080/19336950.2022.2053420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
JZTX-V is a toxin isolated from the venom of the Chinese spider Chilobrachys jingzhao. Previous studies had shown that JZTX-V could inhibit the transient outward potassium current of Kv4.2 and Kv4.3 expressed in Xenopus oocytes but had no effects on Kv1.2–1.4. However, the underlying action mechanism of JZTX-V on Kv4.3 remains unclear. In our study, JZTX-V could inhibit not only transient outward potassium currents evoked in small-sized DRG neurons but also Kv4.3-encoded currents expressed in HEK293T cells in the concentration and voltage dependence. The half maximal inhibitory concentration of JZTX-V on Kv4.3 was 9.6 ± 1.2 nM. In addition, the time course for JZTX-V inhibition and release of inhibition after washout were 15.8 ± 1.54 s and 58.8 ± 4.35 s. Electrophysiological assays indicated that 25 nM JZTX-V could shift significantly the voltage dependence of steady-state activation and steady-state inactivation to depolarization. Meanwhile, 25 nM JZTX-V decreased markedly the time constant of activation and inactivation but had no effect on the time constant of recovery from inactivation. To study the molecular determinants of Kv4.3, we performed alanine scanning on a conserved motif of Kv4.3 and assayed the affinity between mutants and JZTX-V. The results not only showed that I273, L275, V283, and F287 were molecular determinants in the conserved motif of Kv4.3 for interacting with JZTX-V but also speculated the underlying action mechanism that the hydrophobic interaction and steric effects played key roles in the binding of JZTX-V with Kv4.3. In summary, our studies have laid a scientific theoretical foundation for further research on the interaction mechanism between JZTX-V and Kv4.3.
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Affiliation(s)
- Xu Dehong
- Laboratory of Biological Engineering, College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, P. R. China.,Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, P. R. China
| | - Wu Wenmei
- Laboratory of Biological Engineering, College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, P. R. China
| | - Hong Siqin
- Laboratory of Biological Engineering, College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, P. R. China
| | - Zeng Peng
- Laboratory of Biological Engineering, College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, P. R. China
| | - Wang Xianchun
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, P. R. China
| | - Zeng Xiongzhi
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, P. R. China
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11
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Explanation of Structure and Function of kv1.3 Potent Blocker From Mesobuthus eupeus Venom Gland: A New Promise in Drug Development. Jundishapur J Nat Pharm Prod 2022. [DOI: 10.5812/jjnpp.120271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background: Scorpions and other venomous animals are sought with great concern because venom is a source of novel peptides with exciting features. Some toxins of scorpion venom are effectors of potassium channels. Previous studies strongly support the importance of potassium channel toxins for use as pharmacological tools or potential drugs. Objectives: Here, a three-dimensional (3-D) structure and function of a potent acidic blocker of the human voltage-gated potassium ion channel, Kv1.3, previously identified in the scorpion Mesobuthus eupeus venom gland, were interpreted. Methods: The 3-D structure of meuK2-2 was generated using homology modeling. The interaction of meuK2-2 with the Kv1.3 channel was evaluated using a computational protocol employing peptide-protein docking experiments, pose clustering, and 100 ns molecular dynamic simulations to make the 3-D models of the meuK2-2/Kv1.3 complex trustworthy. Results: A CSα/β (cysteine-stabilized α-helical and β-sheet) fold was found for the 3-D structure of meuK2-2. In a different mechanism from what was identified so far, meuK2-2 binds to both turret and pore loop of Kv1.3 through two key residues (Ala28 and Ser11) and H-bonds. The binding of meuK2-2 induces some conformational changes to Kv1.3. Eventually, the side chain of a positively charged amino acid (His9) occupies the channel's pore. All together blocks the ion permeation pathway. Conclusions: MeuK2-2 could block Kv1.3 by a new mechanism. So, it could be a unique target for further investigations to develop a pharmacological tool and potential drug.
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12
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Munc18-dependent and -independent clustering of syntaxin in the plasma membrane of cultured endocrine cells. Proc Natl Acad Sci U S A 2021; 118:2025748118. [PMID: 34857632 DOI: 10.1073/pnas.2025748118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2021] [Indexed: 11/18/2022] Open
Abstract
Syntaxin helps in catalyzing membrane fusion during exocytosis. It also forms clusters in the plasma membrane, where both its transmembrane and SNARE domains are thought to homo-oligomerize. To study syntaxin clustering in live PC12 cells, we labeled granules with neuropeptide-Y-mCherry and syntaxin clusters with syntaxin-1a green fluorescent protein (GFP). Abundant clusters appeared under total internal reflection (TIRF) illumination, and some of them associated with granules ("on-granule clusters"). Syntaxin-1a-GFP or its mutants were expressed at low levels and competed with an excess of endogenous syntaxin for inclusion into clusters. On-granule inclusion was diminished by mutations known to inhibit binding to Munc18-1 in vitro. Knock-down of Munc18-1 revealed Munc18-dependent and -independent on-granule clustering. Clustering was inhibited by mutations expected to break salt bridges between syntaxin's Hb and SNARE domains and was rescued by additional mutations expected to restore them. Most likely, syntaxin is in a closed conformation when it clusters on granules, and its SNARE and Hb domains approach to within atomic distances. Pairwise replacements of Munc18-contacting residues with alanines had only modest effects, except that the pair R114A/I115A essentially abolished on-granule clustering. In summary, an on-granule cluster arises from the specific interaction between a granule and a dense cluster of syntaxin-Munc18-1 complexes. Off-granule clusters, by contrast, were resistant to even the strongest mutations we tried and required neither Munc18-1 nor the presence of a SNARE domain. They may well form through the nonstoichiometric interactions with membrane lipids that others have observed in cell-free systems.
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Aierken A, Xie Y, Dong W, Apaer A, Lin J, Zhao Z, Yang S, Xu Z, Yang F. Rational Design of a Modality-Specific Inhibitor of TRPM8 Channel against Oxaliplatin-Induced Cold Allodynia. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2101717. [PMID: 34658162 PMCID: PMC8596132 DOI: 10.1002/advs.202101717] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 08/10/2021] [Indexed: 06/13/2023]
Abstract
Platinum-based compounds in chemotherapy such as oxaliplatin often induce peripheral neuropathy and neuropathic pain such as cold allodynia in patients. Transient Receptor Potential Melastatin 8 (TRPM8) ion channel is a nociceptor critically involved in such pathological processes. Direct blockade of TRPM8 exhibits significant analgesic effects but also incurs severe side effects such as hypothermia. To selectively target TRPM8 channels against cold allodynia, a cyclic peptide DeC-1.2 is de novo designed with the optimized hot-spot centric approach. DeC-1.2 modality specifically inhibited the ligand activation of TRPM8 but not the cold activation as measured in single-channel patch clamp recordings. It is further demonstrated that DeC-1.2 abolishes cold allodynia in oxaliplatin treated mice without altering body temperature, indicating DeC-1.2 has the potential for further development as a novel analgesic against oxaliplatin-induced neuropathic pain.
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Affiliation(s)
- Aerziguli Aierken
- Department of BiophysicsKidney Disease Center of the First Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang Province310058China
- NHC and CAMS Key Laboratory of Medical NeurobiologyMOE Frontier Science Center for Brain Research and Brain–Machine IntegrationSchool of Brain Science and Brain MedicineZhejiang UniversityHangzhouZhejiang310058China
| | - Ya‐Kai Xie
- NHC and CAMS Key Laboratory of Medical NeurobiologyMOE Frontier Science Center for Brain Research and Brain–Machine IntegrationSchool of Brain Science and Brain MedicineZhejiang UniversityHangzhouZhejiang310058China
- Department of Neurobiology and Department of Anesthesiology of First Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang310058China
| | - Wenqi Dong
- College of Wildlife and Protected AreaNortheast Forestry UniversityHarbin150040China
| | - Abuliken Apaer
- Department of BiophysicsKidney Disease Center of the First Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang Province310058China
| | - Jia‐Jia Lin
- NHC and CAMS Key Laboratory of Medical NeurobiologyMOE Frontier Science Center for Brain Research and Brain–Machine IntegrationSchool of Brain Science and Brain MedicineZhejiang UniversityHangzhouZhejiang310058China
- Department of Neurobiology and Department of Anesthesiology of First Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang310058China
| | - Zihan Zhao
- College of Wildlife and Protected AreaNortheast Forestry UniversityHarbin150040China
| | - Shilong Yang
- College of Wildlife and Protected AreaNortheast Forestry UniversityHarbin150040China
| | - Zhen‐Zhong Xu
- NHC and CAMS Key Laboratory of Medical NeurobiologyMOE Frontier Science Center for Brain Research and Brain–Machine IntegrationSchool of Brain Science and Brain MedicineZhejiang UniversityHangzhouZhejiang310058China
- Department of Neurobiology and Department of Anesthesiology of First Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang310058China
| | - Fan Yang
- Department of BiophysicsKidney Disease Center of the First Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang Province310058China
- NHC and CAMS Key Laboratory of Medical NeurobiologyMOE Frontier Science Center for Brain Research and Brain–Machine IntegrationSchool of Brain Science and Brain MedicineZhejiang UniversityHangzhouZhejiang310058China
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14
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A second S4 movement opens hyperpolarization-activated HCN channels. Proc Natl Acad Sci U S A 2021; 118:2102036118. [PMID: 34504015 DOI: 10.1073/pnas.2102036118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2021] [Indexed: 11/18/2022] Open
Abstract
Rhythmic activity in pacemaker cells, as in the sino-atrial node in the heart, depends on the activation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. As in depolarization-activated K+ channels, the fourth transmembrane segment S4 functions as the voltage sensor in hyperpolarization-activated HCN channels. But how the inward movement of S4 in HCN channels at hyperpolarized voltages couples to channel opening is not understood. Using voltage clamp fluorometry, we found here that S4 in HCN channels moves in two steps in response to hyperpolarizations and that the second S4 step correlates with gate opening. We found a mutation in sea urchin HCN channels that separate the two S4 steps in voltage dependence. The E356A mutation in S4 shifts the main S4 movement to positive voltages, but channel opening remains at negative voltages. In addition, E356A reveals a second S4 movement at negative voltages that correlates with gate opening. Cysteine accessibility and molecular models suggest that the second S4 movement opens up an intracellular crevice between S4 and S5 that would allow radial movement of the intracellular ends of S5 and S6 to open HCN channels.
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15
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Endocannabinoid activation of the TRPV1 ion channel is distinct from activation by capsaicin. J Biol Chem 2021; 297:101022. [PMID: 34332978 PMCID: PMC8387766 DOI: 10.1016/j.jbc.2021.101022] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/25/2021] [Accepted: 07/28/2021] [Indexed: 11/21/2022] Open
Abstract
Transient receptor potential vanilloid 1 (TRPV1) ion channel serves as the detector for noxious temperature above 42 °C, pungent chemicals like capsaicin, and acidic extracellular pH. This channel has also been shown to function as an ionotropic cannabinoid receptor. Despite the solving of high-resolution three-dimensional structures of TRPV1, how endocannabinoids such as anandamide and N-arachidonoyl dopamine bind to and activate this channel remains largely unknown. Here we employed a combination of patch-clamp recording, site-directed mutagenesis, and molecular docking techniques to investigate how the endocannabinoids structurally bind to and open the TRPV1 ion channel. We found that these endocannabinoid ligands bind to the vanilloid-binding pocket of TRPV1 in the “tail-up, head-down” configuration, similar to capsaicin; however, there is a unique interaction with TRPV1 Y512 residue critical for endocannabinoid activation of TRPV1 channels. These data suggest that a differential structural mechanism is involved in TRPV1 activation by endocannabinoids compared with the classic agonist capsaicin.
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16
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Wu X, Perez ME, Noskov SY, Larsson HP. A general mechanism of KCNE1 modulation of KCNQ1 channels involving non-canonical VSD-PD coupling. Commun Biol 2021; 4:887. [PMID: 34285340 PMCID: PMC8292421 DOI: 10.1038/s42003-021-02418-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 07/05/2021] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated KCNQ1 channels contain four separate voltage-sensing domains (VSDs) and a pore domain (PD). KCNQ1 expressed alone opens when the VSDs are in an intermediate state. In cardiomyocytes, KCNQ1 co-expressed with KCNE1 opens mainly when the VSDs are in a fully activated state. KCNE1 also drastically slows the opening of KCNQ1 channels and shifts the voltage dependence of opening by >40 mV. We here show that mutations of conserved residues at the VSD-PD interface alter the VSD-PD coupling so that the mutant KCNQ1/KCNE1 channels open in the intermediate VSD state. Using recent structures of KCNQ1 and KCNE beta subunits in different states, we present a mechanism by which KCNE1 rotates the VSD relative to the PD and affects the VSD-PD coupling of KCNQ1 channels in a non-canonical way, forcing KCNQ1/KCNE1 channels to open in the fully-activated VSD state. This would explain many of the KCNE1-induced effects on KCNQ1 channels.
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Affiliation(s)
- Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Marta E Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Sergei Yu Noskov
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - H Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA.
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17
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Gubič Š, Hendrickx LA, Toplak Ž, Sterle M, Peigneur S, Tomašič T, Pardo LA, Tytgat J, Zega A, Mašič LP. Discovery of K V 1.3 ion channel inhibitors: Medicinal chemistry approaches and challenges. Med Res Rev 2021; 41:2423-2473. [PMID: 33932253 PMCID: PMC8252768 DOI: 10.1002/med.21800] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 03/03/2021] [Accepted: 03/19/2021] [Indexed: 12/12/2022]
Abstract
The KV 1.3 voltage-gated potassium ion channel is involved in many physiological processes both at the plasma membrane and in the mitochondria, chiefly in the immune and nervous systems. Therapeutic targeting KV 1.3 with specific peptides and small molecule inhibitors shows great potential for treating cancers and autoimmune diseases, such as multiple sclerosis, type I diabetes mellitus, psoriasis, contact dermatitis, rheumatoid arthritis, and myasthenia gravis. However, no KV 1.3-targeted compounds have been approved for therapeutic use to date. This review focuses on the presentation of approaches for discovering new KV 1.3 peptide and small-molecule inhibitors, and strategies to improve the selectivity of active compounds toward KV 1.3. Selectivity of dalatazide (ShK-186), a synthetic derivate of the sea anemone toxin ShK, was achieved by chemical modification and has successfully reached clinical trials as a potential therapeutic for treating autoimmune diseases. Other peptides and small-molecule inhibitors are critically evaluated for their lead-like characteristics and potential for progression into clinical development. Some small-molecule inhibitors with well-defined structure-activity relationships have been optimized for selective delivery to mitochondria, and these offer therapeutic potential for the treatment of cancers. This overview of KV 1.3 inhibitors and methodologies is designed to provide a good starting point for drug discovery to identify novel effective KV 1.3 modulators against this target in the future.
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Affiliation(s)
- Špela Gubič
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
| | - Louise A. Hendrickx
- Toxicology and PharmacologyUniversity of Leuven, Campus GasthuisbergLeuvenBelgium
| | - Žan Toplak
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
| | - Maša Sterle
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
| | - Steve Peigneur
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
| | | | - Luis A. Pardo
- AG OncophysiologyMax‐Planck Institute for Experimental MedicineGöttingenGermany
| | - Jan Tytgat
- Toxicology and PharmacologyUniversity of Leuven, Campus GasthuisbergLeuvenBelgium
| | - Anamarija Zega
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
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18
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Xu L, Han Y, Chen X, Aierken A, Wen H, Zheng W, Wang H, Lu X, Zhao Z, Ma C, Liang P, Yang W, Yang S, Yang F. Molecular mechanisms underlying menthol binding and activation of TRPM8 ion channel. Nat Commun 2020; 11:3790. [PMID: 32728032 PMCID: PMC7391767 DOI: 10.1038/s41467-020-17582-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/06/2020] [Indexed: 02/07/2023] Open
Abstract
Menthol in mints elicits coolness sensation by selectively activating TRPM8 channel. Although structures of TRPM8 were determined in the apo and liganded states, the menthol-bounded state is unresolved. To understand how menthol activates the channel, we docked menthol to the channel and systematically validated our menthol binding models with thermodynamic mutant cycle analysis. We observed that menthol uses its hydroxyl group as a hand to specifically grab with R842, and its isopropyl group as legs to stand on I846 and L843. By imaging with fluorescent unnatural amino acid, we found that menthol binding induces wide-spread conformational rearrangements within the transmembrane domains. By Φ analysis based on single-channel recordings, we observed a temporal sequence of conformational changes in the S6 bundle crossing and the selectivity filter leading to channel activation. Therefore, our study suggested a 'grab and stand' mechanism of menthol binding and how menthol activates TRPM8 at the atomic level.
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Affiliation(s)
- Lizhen Xu
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, Zhejiang Province, China
| | - Yalan Han
- 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, 650223, Kunming, Yunnan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoying Chen
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, Zhejiang Province, China
| | - Aerziguli Aierken
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, Zhejiang Province, China
| | - Han Wen
- Department of Physics, State University of New York at Buffalo, Buffalo, NY, USA
| | - Wenjun Zheng
- Department of Physics, State University of New York at Buffalo, Buffalo, NY, USA
| | - Hongkun Wang
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, The First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang, China
- Institute of Translational Medicine, Zhejiang University, Zhejiang, China
| | - Xiancui Lu
- 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, 650223, Kunming, Yunnan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhenye Zhao
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, Zhejiang Province, China
| | - Cheng Ma
- Protein facility, School of Medicine, Zhejiang University, Zhejiang, China
| | - Ping Liang
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, The First Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang, China
- Institute of Translational Medicine, Zhejiang University, Zhejiang, China
| | - Wei Yang
- Department of Biophysics, and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, Zhejiang Province, China.
| | - Shilong Yang
- College of Wildlife and Protected Area, Northeast Forestry University, 150040, Harbin, China.
| | - Fan Yang
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, Zhejiang Province, China.
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19
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Abbott GW. KCNQs: Ligand- and Voltage-Gated Potassium Channels. Front Physiol 2020; 11:583. [PMID: 32655402 PMCID: PMC7324551 DOI: 10.3389/fphys.2020.00583] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/11/2020] [Indexed: 12/26/2022] Open
Abstract
Voltage-gated potassium (Kv) channels in the KCNQ (Kv7) family are essential features of a broad range of excitable and non-excitable cell types and are found in organisms ranging from Hydra vulgaris to Homo sapiens. Although they are firmly in the superfamily of S4 domain-bearing voltage-sensing ion channels, KCNQ channels are highly sensitive to a range of endogenous and exogenous small molecules that act directly on the pore, the voltage-sensing domain, or the interface between the two. The focus of this review is regulation of KCNQs by direct binding of neurotransmitters and metabolites from both animals and plants and the role of the latter in the effects of plants consumed for food and as traditional folk medicines. The conceptual question arises: Are KCNQs voltage-gated channels that are also sensitive to ligands or ligand-gated channels that are also sensitive to voltage?
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
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20
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Pore-modulating toxins exploit inherent slow inactivation to block K + channels. Proc Natl Acad Sci U S A 2019; 116:18700-18709. [PMID: 31444298 DOI: 10.1073/pnas.1908903116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Voltage-dependent potassium channels (Kvs) gate in response to changes in electrical membrane potential by coupling a voltage-sensing module with a K+-selective pore. Animal toxins targeting Kvs are classified as pore blockers, which physically plug the ion conduction pathway, or as gating modifiers, which disrupt voltage sensor movements. A third group of toxins blocks K+ conduction by an unknown mechanism via binding to the channel turrets. Here, we show that Conkunitzin-S1 (Cs1), a peptide toxin isolated from cone snail venom, binds at the turrets of Kv1.2 and targets a network of hydrogen bonds that govern water access to the peripheral cavities that surround the central pore. The resulting ectopic water flow triggers an asymmetric collapse of the pore by a process resembling that of inherent slow inactivation. Pore modulation by animal toxins exposes the peripheral cavity of K+ channels as a novel pharmacological target and provides a rational framework for drug design.
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21
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Li B, Silva JR, Lu X, Luo L, Wang Y, Xu L, Aierken A, Shynykul Z, Kamau PM, Luo A, Yang J, Su D, Yang F, Cui J, Yang S, Lai R. Molecular game theory for a toxin-dominant food chain model. Natl Sci Rev 2019; 6:1191-1200. [PMID: 34691998 PMCID: PMC8291550 DOI: 10.1093/nsr/nwz097] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/23/2019] [Accepted: 07/02/2019] [Indexed: 12/30/2022] Open
Abstract
Animal toxins that are used to subdue prey and deter predators act as the key drivers in natural food chains and ecosystems. However, the predators of venomous animals may exploit feeding adaptation strategies to overcome toxins their prey produce. Much remains unknown about the genetic and molecular game process in the toxin-dominant food chain model. Here, we show an evolutionary strategy in different trophic levels of scorpion-eating amphibians, scorpions and insects, representing each predation relationship in habitats dominated by the paralytic toxins of scorpions. For scorpions preying on insects, we found that the scorpion α-toxins irreversibly activate the skeletal muscle sodium channel of their prey (insect, BgNaV1) through a membrane delivery mechanism and an efficient binding with the Asp/Lys-Tyr motif of BgNaV1. However, in the predatory game between frogs and scorpions, with a single point mutation (Lys to Glu) in this motif of the frog's skeletal muscle sodium channel (fNaV1.4), fNaV1.4 breaks this interaction and diminishes muscular toxicity to the frog; thus, frogs can regularly prey on scorpions without showing paralysis. Interestingly, this molecular strategy also has been employed by some other scorpion-eating amphibians, especially anurans. In contrast to these amphibians, the Asp/Lys-Tyr motifs are structurally and functionally conserved in other animals that do not prey on scorpions. Together, our findings elucidate the protein-protein interacting mechanism of a toxin-dominant predator-prey system, implying the evolutionary game theory at a molecular level.
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Affiliation(s)
- 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 650223, China
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University St. Louis, MO 63130, UK
| | - Xiancui Lu
- 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 650223, China
- University of Chinese Academy of Sciences, Beijing 100049, 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 650223, China
| | - Yunfei Wang
- 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 650223, China
| | - Lizhen Xu
- Key Laboratory of Medical Neurobiology, Department of Biophysics and Kidney Disease Center, First Affiliated Hospital, Institute of Neuroscience, National Health Commission and Chinese Academy of Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Aerziguli Aierken
- Key Laboratory of Medical Neurobiology, Department of Biophysics and Kidney Disease Center, First Affiliated Hospital, Institute of Neuroscience, National Health Commission and Chinese Academy of Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Zhanserik Shynykul
- 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 650223, China
| | - Peter Muiruri Kamau
- 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 650223, China
| | - Anna 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 650223, China
| | - Jian 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 650223, China
- Department of Biological Sciences, Columbia University, New York, NY 10027, UK
| | - Deyuan Su
- 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 650223, China
| | - Fan Yang
- Key Laboratory of Medical Neurobiology, Department of Biophysics and Kidney Disease Center, First Affiliated Hospital, Institute of Neuroscience, National Health Commission and Chinese Academy of Medical Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University St. Louis, MO 63130, UK
| | - 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 650223, China
| | - 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 650223, China
- KIZ/CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming 650223, China
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22
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Moldenhauer H, Díaz-Franulic I, Poblete H, Naranjo D. Trans-toxin ion-sensitivity of charybdotoxin-blocked potassium-channels reveals unbinding transitional states. eLife 2019; 8:46170. [PMID: 31271355 PMCID: PMC6660193 DOI: 10.7554/elife.46170] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/04/2019] [Indexed: 12/11/2022] Open
Abstract
In silico and in vitro studies have made progress in understanding protein–protein complex formation; however, the molecular mechanisms for their dissociation are unclear. Protein–protein complexes, lasting from microseconds to years, often involve induced-fit, challenging computational or kinetic analysis. Charybdotoxin (CTX), a peptide from the Leiurus scorpion venom, blocks voltage-gated K+-channels in a unique example of binding/unbinding simplicity. CTX plugs the external mouth of K+-channels pore, stopping K+-ion conduction, without inducing conformational changes. Conflicting with a tight binding, we show that external permeant ions enhance CTX-dissociation, implying a path connecting the pore, in the toxin-bound channel, with the external solution. This sensitivity is explained if CTX wobbles between several bound conformations, producing transient events that restore the electrical and ionic trans-pore gradients. Wobbling may originate from a network of contacts in the interaction interface that are in dynamic stochastic equilibria. These partially-bound intermediates could lead to distinct, and potentially manipulable, dissociation pathways.
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Affiliation(s)
- Hans Moldenhauer
- Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ignacio Díaz-Franulic
- Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Horacio Poblete
- Núcleo Científico Multidisciplinario, Dirección de Investigación. Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, and Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Talca, Talca, Chile
| | - David Naranjo
- Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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23
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Wang Y, Lan W, Yan Z, Gao J, Liu X, Wang S, Guo X, Wang C, Zhou H, Ding J, Cao C. Solution structure of extracellular loop of human β4 subunit of BK channel and its biological implication on ChTX sensitivity. Sci Rep 2018; 8:4571. [PMID: 29545539 PMCID: PMC5854672 DOI: 10.1038/s41598-018-23016-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/05/2018] [Indexed: 01/06/2023] Open
Abstract
Large-conductance Ca2+- and voltage-dependent K+ (BK) channels display diverse biological functions while their pore-forming α subunit is coded by a single Slo1 gene. The variety of BK channels is correlated with the effects of BKα coexpression with auxiliary β (β1-β4) subunits, as well as newly defined γ subunits. Charybdotoxin (ChTX) blocks BK channel through physically occluding the K+-conduction pore. Human brain enriched β4 subunit (hβ4) alters the conductance-voltage curve, slows activation and deactivation time courses of BK channels. Its extracellular loop (hβ4-loop) specifically impedes ChTX to bind BK channel pore. However, the structure of β4 subunit's extracellular loop and the molecular mechanism for gating kinetics, toxin sensitivity of BK channels regulated by β4 are still unclear. To address them, here, we first identified four disulfide bonds in hβ4-loop by mass spectroscopy and NMR techniques. Then we determined its three-dimensional solution structure, performed NMR titration and electrophysiological analysis, and found that residue Asn123 of β4 subunit regulated the gating and pharmacological characteristics of BK channel. Finally, by constructing structure models of BKα/β4 and thermodynamic double-mutant cycle analysis, we proposed that BKα subunit might interact with β4 subunit through the conserved residue Glu264(BKα) coupling with residue Asn123(β4).
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Affiliation(s)
- Yanting Wang
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (CAS), 345 Lingling Road, Shanghai, 200032, China.,Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, Hubei, China
| | - Wenxian Lan
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (CAS), 345 Lingling Road, Shanghai, 200032, China
| | - Zhenzhen Yan
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, Hubei, China
| | - Jing Gao
- Department of Analytical Chemistry, Shanghai Institute of Materia Medica, CAS, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Xinlian Liu
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (CAS), 345 Lingling Road, Shanghai, 200032, China
| | - Sheng Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, Hubei, China
| | - Xiying Guo
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, Hubei, China
| | - Chunxi Wang
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (CAS), 345 Lingling Road, Shanghai, 200032, China
| | - Hu Zhou
- Department of Analytical Chemistry, Shanghai Institute of Materia Medica, CAS, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Jiuping Ding
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, Hubei, China
| | - Chunyang Cao
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (CAS), 345 Lingling Road, Shanghai, 200032, China. .,University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China. .,Collaborative Innovation Center of Chemistry for Life Sciences, Chinese Academy of Sciences (CAS), 345 Lingling Road, Shanghai, 200032, China.
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Na V 1.7 as a Pharmacogenomic Target for Pain: Moving Toward Precision Medicine. Trends Pharmacol Sci 2018; 39:258-275. [DOI: 10.1016/j.tips.2017.11.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 11/27/2017] [Accepted: 11/29/2017] [Indexed: 01/15/2023]
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Abstract
The work showed that centipede venom can cause disorders in cardiovascular, respiratory, and nervous systems. The cardiovascular toxicity of the venom comes mostly from a peptide toxin SsTx, which blocks the KCNQ family of potassium channels. Retigabine, a KCNQ channel opener, neutralizes centipede venom toxicity, and thus could be used to treat centipede envenomation. Centipedes can subdue giant prey by using venom, which is metabolically expensive to synthesize and thus used frugally through efficiently disrupting essential physiological systems. Here, we show that a centipede (Scolopendra subspinipes mutilans, ∼3 g) can subdue a mouse (∼45 g) within 30 seconds. We found that this observation is largely due to a peptide toxin in the venom, SsTx, and further established that SsTx blocks KCNQ potassium channels to exert the lethal toxicity. We also demonstrated that a KCNQ opener, retigabine, neutralizes the toxicity of a centipede’s venom. The study indicates that centipedes’ venom has evolved to simultaneously disrupt cardiovascular, respiratory, muscular, and nervous systems by targeting the broadly distributed KCNQ channels, thus providing a therapeutic strategy for centipede envenomation.
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Yuan S, Gao B, Zhu S. Molecular Dynamics Simulation Reveals Specific Interaction Sites between Scorpion Toxins and K v1.2 Channel: Implications for Design of Highly Selective Drugs. Toxins (Basel) 2017; 9:toxins9110354. [PMID: 29104247 PMCID: PMC5705969 DOI: 10.3390/toxins9110354] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/15/2017] [Accepted: 10/19/2017] [Indexed: 01/06/2023] Open
Abstract
The Kv1.2 channel plays an important role in the maintenance of resting membrane potential and the regulation of the cellular excitability of neurons, whose silencing or mutations can elicit neuropathic pain or neurological diseases (e.g., epilepsy and ataxia). Scorpion venom contains a variety of peptide toxins targeting the pore region of this channel. Despite a large amount of structural and functional data currently available, their detailed interaction modes are poorly understood. In this work, we choose four Kv1.2-targeted scorpion toxins (Margatoxin, Agitoxin-2, OsK-1, and Mesomartoxin) to construct their complexes with Kv1.2 based on the experimental structure of ChTx-Kv1.2. Molecular dynamics simulation of these complexes lead to the identification of hydrophobic patches, hydrogen-bonds, and salt bridges as three essential forces mediating the interactions between this channel and the toxins, in which four Kv1.2-specific interacting amino acids (D353, Q358, V381, and T383) are identified for the first time. This discovery might help design highly selective Kv1.2-channel inhibitors by altering amino acids of these toxins binding to the four channel residues. Finally, our results provide new evidence in favor of an induced fit model between scorpion toxins and K+ channel interactions.
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Affiliation(s)
- Shouli Yuan
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Bin Gao
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Shunyi Zhu
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
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Abstract
Sack discusses the evolution of toxin research in JGP over the last 100 years. Toxins are the poisonous products of organisms. Toxins serve vital defensive and offensive functions for those that harbor them: stinging scorpions, pesticidal plants, sanguinary snakes, fearless frogs, sliming snails, noxious newts, and smarting spiders. For physiologists, toxins are integral chemical tools that hijack life’s fundamental processes with remarkable molecular specificity. Our understanding of electrophysiological phenomena has been transformed time and time again with the help of some terrifying toxins. For this reason, studies of toxin mechanism are an important and enduring facet of The Journal of General Physiology (JGP). This Milestone in Physiology reflects on toxins studied in JGP over its first 100 years, what they have taught us, and what they have yet to reveal.
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Affiliation(s)
- Jon T Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA .,Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA
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28
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Rahman S, Luetje CW. Mutant cycle analysis identifies a ligand interaction site in an odorant receptor of the malaria vector Anopheles gambiae. J Biol Chem 2017; 292:18916-18923. [PMID: 28972152 DOI: 10.1074/jbc.m117.810374] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/27/2017] [Indexed: 12/29/2022] Open
Abstract
Lack of information about the structure of insect odorant receptors (ORs) hinders the development of more effective repellants to control disease-transmitting insects. Mutagenesis and functional analyses using agonists to map the odorant-binding sites of these receptors have been limited because mutations distant from an agonist-binding site can alter agonist sensitivity. Here we use mutant cycle analysis, an approach for exploring the energetics of protein-protein or protein-ligand interactions, with inhibitors, to identify a component of the odorant-binding site of an OR from the malaria vector, Anopheles gambiae The closely related odorant-specificity subunits Agam/Or15 and Agam/Or13 were each co-expressed with Agam/Orco (odorant receptor co-receptor subunit) in Xenopus oocytes and assayed by two-electrode voltage clamp electrophysiology. We identified (-)-fenchone as a competitive inhibitor with different potencies at the two receptors and used this difference to screen a panel of 37 Agam/Or15 mutants, surveying all positions that differ between Agam/Or15 and Agam/Or13 in the transmembrane and extracellular regions, identifying position 195 as a determinant of (-)-fenchone sensitivity. Inhibition by (-)-fenchone and six structurally related inhibitors of Agam/Or15 receptors containing each of four different hydrophobic residues at position 195 served as input data for mutant cycle analysis. Several mutant cycles, calculated from the inhibition of two receptors by each of two ligands, yielded coupling energies of ≥1 kcal/mol, indicating a close, physical interaction between the ligand and residue 195 of Agam/Or15. This approach should be useful in further expanding our knowledge of odorant-binding site structures in ORs of disease vector insects.
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Affiliation(s)
- Suhaila Rahman
- From the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33101
| | - Charles W Luetje
- From the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33101
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29
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Structural basis of subunit selectivity for competitive NMDA receptor antagonists with preference for GluN2A over GluN2B subunits. Proc Natl Acad Sci U S A 2017; 114:E6942-E6951. [PMID: 28760974 PMCID: PMC5565460 DOI: 10.1073/pnas.1707752114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
NMDA-type glutamate receptors are ligand-gated ion channels that contribute to excitatory neurotransmission in the central nervous system (CNS). Most NMDA receptors comprise two glycine-binding GluN1 and two glutamate-binding GluN2 subunits (GluN2A-D). We describe highly potent (S)-5-[(R)-2-amino-2-carboxyethyl]-4,5-dihydro-1H-pyrazole-3-carboxylic acid (ACEPC) competitive GluN2 antagonists, of which ST3 has a binding affinity of 52 nM at GluN1/2A and 782 nM at GluN1/2B receptors. This 15-fold preference of ST3 for GluN1/2A over GluN1/2B is improved compared with NVP-AAM077, a widely used GluN2A-selective antagonist, which we show has 11-fold preference for GluN1/2A over GluN1/2B. Crystal structures of the GluN1/2A agonist binding domain (ABD) heterodimer with bound ACEPC antagonists reveal a binding mode in which the ligands occupy a cavity that extends toward the subunit interface between GluN1 and GluN2A ABDs. Mutational analyses show that the GluN2A preference of ST3 is primarily mediated by four nonconserved residues that are not directly contacting the ligand, but positioned within 12 Å of the glutamate binding site. Two of these residues influence the cavity occupied by ST3 in a manner that results in favorable binding to GluN2A, but occludes binding to GluN2B. Thus, we reveal opportunities for the design of subunit-selective competitive NMDA receptor antagonists by identifying a cavity for ligand binding in which variations exist between GluN2A and GluN2B subunits. This structural insight suggests that subunit selectivity of glutamate-site antagonists can be mediated by mechanisms in addition to direct contributions of contact residues to binding affinity.
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Venom-derived peptide inhibitors of voltage-gated potassium channels. Neuropharmacology 2017; 127:124-138. [PMID: 28689025 DOI: 10.1016/j.neuropharm.2017.07.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/02/2017] [Accepted: 07/04/2017] [Indexed: 12/11/2022]
Abstract
Voltage-gated potassium channels play a key role in human physiology and pathology. Reflecting their importance, numerous channelopathies have been characterised that arise from mutations in these channels or from autoimmune attack on the channels. Voltage-gated potassium channels are also the target of a broad range of peptide toxins from venomous organisms, including sea anemones, scorpions, spiders, snakes and cone snails; many of these peptides bind to the channels with high potency and selectivity. In this review we describe the various classes of peptide toxins that block these channels and illustrate the broad range of three-dimensional structures that support channel blockade. The therapeutic opportunities afforded by these peptides are also highlighted. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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31
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Understand spiciness: mechanism of TRPV1 channel activation by capsaicin. Protein Cell 2017; 8:169-177. [PMID: 28044278 PMCID: PMC5326624 DOI: 10.1007/s13238-016-0353-7] [Citation(s) in RCA: 181] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/22/2016] [Indexed: 11/06/2022] Open
Abstract
Capsaicin in chili peppers bestows the sensation of spiciness. Since the discovery of its receptor, transient receptor potential vanilloid 1 (TRPV1) ion channel, how capsaicin activates this channel has been under extensive investigation using a variety of experimental techniques including mutagenesis, patch-clamp recording, crystallography, cryo-electron microscopy, computational docking and molecular dynamic simulation. A framework of how capsaicin binds and activates TRPV1 has started to merge: capsaicin binds to a pocket formed by the channel’s transmembrane segments, where it takes a “tail-up, head-down” configuration. Binding is mediated by both hydrogen bonds and van der Waals interactions. Upon binding, capsaicin stabilizes the open state of TRPV1 by “pull-and-contact” with the S4-S5 linker. Understanding the ligand-host interaction will greatly facilitate pharmaceutical efforts to develop novel analgesics targeting TRPV1.
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32
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Latorre R, Castillo K, Carrasquel-Ursulaez W, Sepulveda RV, Gonzalez-Nilo F, Gonzalez C, Alvarez O. Molecular Determinants of BK Channel Functional Diversity and Functioning. Physiol Rev 2017; 97:39-87. [DOI: 10.1152/physrev.00001.2016] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Large-conductance Ca2+- and voltage-activated K+ (BK) channels play many physiological roles ranging from the maintenance of smooth muscle tone to hearing and neurosecretion. BK channels are tetramers in which the pore-forming α subunit is coded by a single gene ( Slowpoke, KCNMA1). In this review, we first highlight the physiological importance of this ubiquitous channel, emphasizing the role that BK channels play in different channelopathies. We next discuss the modular nature of BK channel-forming protein, in which the different modules (the voltage sensor and the Ca2+ binding sites) communicate with the pore gates allosterically. In this regard, we review in detail the allosteric models proposed to explain channel activation and how the models are related to channel structure. Considering their extremely large conductance and unique selectivity to K+, we also offer an account of how these two apparently paradoxical characteristics can be understood consistently in unison, and what we have learned about the conduction system and the activation gates using ions, blockers, and toxins. Attention is paid here to the molecular nature of the voltage sensor and the Ca2+ binding sites that are located in a gating ring of known crystal structure and constituted by four COOH termini. Despite the fact that BK channels are coded by a single gene, diversity is obtained by means of alternative splicing and modulatory β and γ subunits. We finish this review by describing how the association of the α subunit with β or with γ subunits can change the BK channel phenotype and pharmacology.
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Affiliation(s)
- Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Willy Carrasquel-Ursulaez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Romina V. Sepulveda
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Fernando Gonzalez-Nilo
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Carlos Gonzalez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Osvaldo Alvarez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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Nekrasova OV, Volyntseva AD, Kudryashova KS, Novoseletsky VN, Lyapina EA, Illarionova AV, Yakimov SA, Korolkova YV, Shaitan KV, Kirpichnikov MP, Feofanov AV. Complexes of Peptide Blockers with Kv1.6 Pore Domain: Molecular Modeling and Studies with KcsA-Kv1.6 Channel. J Neuroimmune Pharmacol 2016; 12:260-276. [PMID: 27640211 DOI: 10.1007/s11481-016-9710-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/09/2016] [Indexed: 11/25/2022]
Abstract
Potassium voltage-gated Kv1.6 channel, which is distributed primarily in neurons of central and peripheral nervous systems, is of significant physiological importance. To date, several high-affinity Kv1.6-channel blockers are known, but the lack of selective ones among them hampers the studies of tissue localization and functioning of Kv1.6 channels. Here we present an approach to advanced understanding of interactions of peptide toxin blockers with a Kv1.6 pore. It combines molecular modeling studies and an application of a new bioengineering system based on a KcsA-Kv1.6 hybrid channel for the quantitative fluorescent analysis of blocker-channel interactions. Using this system we demonstrate that peptide toxins agitoxin 2, kaliotoxin1 and OSK1 have similar high affinity to the extracellular vestibule of the K+-conducting pore of Kv1.6, hetlaxin is a low-affinity ligand, whereas margatoxin and scyllatoxin do not bind to Kv1.6 pore. Binding of toxins to Kv1.6 pore has considerable inverse dependence on the ionic strength. Model structures of KcsA-Kv1.6 and Kv1.6 complexes with agitoxin 2, kaliotoxin 1 and OSK1 were obtained using homology modeling and molecular dynamics simulation. Interaction interfaces, which are formed by 15-19 toxin residues and 10 channel residues, are described and compared. Specific sites of Kv1.6 pore recognition are identified for targeting of peptide blockers. Analysis of interactions between agitoxin 2 derivatives with point mutations (S7K, S11G, L19S, R31G) and KcsA-Kv1.6 confirms reliability of the calculated complex structure.
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Affiliation(s)
- O V Nekrasova
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - A D Volyntseva
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia
| | - K S Kudryashova
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - V N Novoseletsky
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia
| | - E A Lyapina
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia
| | - A V Illarionova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - S A Yakimov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - Yu V Korolkova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - K V Shaitan
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia
| | - M P Kirpichnikov
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - A V Feofanov
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia. .,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia.
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TRPV1: A Target for Rational Drug Design. Pharmaceuticals (Basel) 2016; 9:ph9030052. [PMID: 27563913 PMCID: PMC5039505 DOI: 10.3390/ph9030052] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/12/2016] [Accepted: 08/18/2016] [Indexed: 12/18/2022] Open
Abstract
Transient Receptor Potential Vanilloid 1 (TRPV1) is a non-selective, Ca2+ permeable cation channel activated by noxious heat, and chemical ligands, such as capsaicin and resiniferatoxin (RTX). Many compounds have been developed that either activate or inhibit TRPV1, but none of them are in routine clinical practice. This review will discuss the rationale for antagonists and agonists of TRPV1 for pain relief and other conditions, and strategies to develop new, better drugs to target this ion channel, using the newly available high-resolution structures.
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35
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Poelwijk FJ, Krishna V, Ranganathan R. The Context-Dependence of Mutations: A Linkage of Formalisms. PLoS Comput Biol 2016; 12:e1004771. [PMID: 27337695 PMCID: PMC4919011 DOI: 10.1371/journal.pcbi.1004771] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Frank J. Poelwijk
- Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (FJP); (RR)
| | - Vinod Krishna
- Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Rama Ranganathan
- Green Center for Systems Biology and Departments of Biophysics and Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (FJP); (RR)
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36
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Díaz-Franulic I, Caceres-Molina J, Sepulveda RV, Gonzalez-Nilo F, Latorre R. Structure-Driven Pharmacology of Transient Receptor Potential Channel Vanilloid 1. Mol Pharmacol 2016; 90:300-8. [PMID: 27335334 DOI: 10.1124/mol.116.104430] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Accepted: 06/16/2016] [Indexed: 01/08/2023] Open
Abstract
The transient receptor potential vanilloid 1 (TRPV1) ion channel is a polymodal receptor that mediates the flux of cations across the membrane in response to several stimuli, including heat, voltage, and ligands. The best known agonist of TRPV1 channels is capsaicin, the pungent component of "hot" chili peppers. In addition, peptides found in the venom of poisonous animals, along with the lipids phosphatidylinositol 4,5-biphosphate, lysophosphatidic acid, and cholesterol, bind to TRPV1 with high affinity to modulate channel gating. Here, we discuss the functional evidence regarding ligand-dependent activation of TRPV1 channels in light of structural data recently obtained by cryoelectron microscopy. This review focuses on the mechanistic insights into ligand binding and allosteric gating of TRPV1 channels and the relevance of accurate polymodal receptor biophysical characterization for drug design in novel pain therapies.
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Affiliation(s)
- Ignacio Díaz-Franulic
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile (I.D.-F., R.L., F.G.-N.); Centro de Bioinformática y Biología Integrativa, Universidad Andrés Bello, Santiago, Chile (I.D.-F., J.C.-M., R.V.S., F.G.-N.); and Fraunhofer Chile Research, Santiago, Chile (I.D.-F.)
| | - Javier Caceres-Molina
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile (I.D.-F., R.L., F.G.-N.); Centro de Bioinformática y Biología Integrativa, Universidad Andrés Bello, Santiago, Chile (I.D.-F., J.C.-M., R.V.S., F.G.-N.); and Fraunhofer Chile Research, Santiago, Chile (I.D.-F.)
| | - Romina V Sepulveda
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile (I.D.-F., R.L., F.G.-N.); Centro de Bioinformática y Biología Integrativa, Universidad Andrés Bello, Santiago, Chile (I.D.-F., J.C.-M., R.V.S., F.G.-N.); and Fraunhofer Chile Research, Santiago, Chile (I.D.-F.)
| | - Fernando Gonzalez-Nilo
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile (I.D.-F., R.L., F.G.-N.); Centro de Bioinformática y Biología Integrativa, Universidad Andrés Bello, Santiago, Chile (I.D.-F., J.C.-M., R.V.S., F.G.-N.); and Fraunhofer Chile Research, Santiago, Chile (I.D.-F.)
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile (I.D.-F., R.L., F.G.-N.); Centro de Bioinformática y Biología Integrativa, Universidad Andrés Bello, Santiago, Chile (I.D.-F., J.C.-M., R.V.S., F.G.-N.); and Fraunhofer Chile Research, Santiago, Chile (I.D.-F.)
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Okuda H, Yonezawa Y, Takano Y, Okamura Y, Fujiwara Y. Direct Interaction between the Voltage Sensors Produces Cooperative Sustained Deactivation in Voltage-gated H+ Channel Dimers. J Biol Chem 2016; 291:5935-5947. [PMID: 26755722 PMCID: PMC4786727 DOI: 10.1074/jbc.m115.666834] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 12/23/2015] [Indexed: 01/31/2023] Open
Abstract
The voltage-gated H(+) channel (Hv) is a voltage sensor domain-like protein consisting of four transmembrane segments (S1-S4). The native Hv structure is a homodimer, with the two channel subunits functioning cooperatively. Here we show that the two voltage sensor S4 helices within the dimer directly cooperate via a π-stacking interaction between Trp residues at the middle of each segment. Scanning mutagenesis showed that Trp situated around the original position provides the slow gating kinetics characteristic of the dimer's cooperativity. Analyses of the Trp mutation on the dimeric and monomeric channel backgrounds and analyses with tandem channel constructs suggested that the two Trp residues within the dimer are functionally coupled during Hv deactivation but are less so during activation. Molecular dynamics simulation also showed direct π-stacking of the two Trp residues. These results provide new insight into the cooperative function of voltage-gated channels, where adjacent voltage sensor helices make direct physical contact and work as a single unit according to the gating process.
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Affiliation(s)
- Hiroko Okuda
- From Division of Integrative Physiology, Graduate School of Medicine
| | - Yasushige Yonezawa
- the High Pressure Protein Research Center, Institute of Advanced Technology, Kinki University, Kinokawa 649-6493, Wakayama, Japan, and
| | - Yu Takano
- the Institute for Protein Research, and; the Graduate School of Information Sciences, Hiroshima City University, Hiroshima 731-3194, Hiroshima, Japan
| | - Yasushi Okamura
- From Division of Integrative Physiology, Graduate School of Medicine,; the Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Osaka, Japan
| | - Yuichiro Fujiwara
- From Division of Integrative Physiology, Graduate School of Medicine,.
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Effects of deletion and insertion of amino acids on the activity of HelaTx1, a scorpion toxin on potassium channels. Toxicon 2016; 111:1-5. [DOI: 10.1016/j.toxicon.2015.12.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/18/2015] [Accepted: 12/22/2015] [Indexed: 11/24/2022]
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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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40
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Abstract
KCNE β-subunits assemble with and modulate the properties of voltage-gated K(+) channels. In the colon, stomach, and kidney, KCNE3 coassembles with the α-subunit KCNQ1 to form K(+) channels important for K(+) and Cl(-) secretion that appear to be voltage-independent. How KCNE3 subunits turn voltage-gated KCNQ1 channels into apparent voltage-independent KCNQ1/KCNE3 channels is not completely understood. Different mechanisms have been proposed to explain the effect of KCNE3 on KCNQ1 channels. Here, we use voltage clamp fluorometry to determine how KCNE3 affects the voltage sensor S4 and the gate of KCNQ1. We find that S4 moves in KCNQ1/KCNE3 channels, and that inward S4 movement closes the channel gate. However, KCNE3 shifts the voltage dependence of S4 movement to extreme hyperpolarized potentials, such that in the physiological voltage range, the channel is constitutively conducting. By separating S4 movement and gate opening, either by a mutation or PIP2 depletion, we show that KCNE3 directly affects the S4 movement in KCNQ1. Two negatively charged residues of KCNE3 (D54 and D55) are found essential for the effect of KCNE3 on KCNQ1 channels, mainly exerting their effects by an electrostatic interaction with R228 in S4. Our results suggest that KCNE3 primarily affects the voltage-sensing domain and only indirectly affects the gate.
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Meirovitch E, Tchaicheeyan O, Sher I, Norton RS, Chill JH. Structural Dynamics of the Potassium Channel Blocker ShK: SRLS Analysis of 15N Relaxation. J Phys Chem B 2015; 119:15130-7. [DOI: 10.1021/acs.jpcb.5b07875] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Eva Meirovitch
- The
Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Oren Tchaicheeyan
- The
Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Inbal Sher
- Chemistry
Department, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Raymond S. Norton
- Medicinal
Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Jordan H. Chill
- Chemistry
Department, Bar-Ilan University, Ramat-Gan 52900, Israel
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42
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Pessoa J, Fonseca F, Furini S, Morais-Cabral JH. Determinants of ligand selectivity in a cyclic nucleotide-regulated potassium channel. ACTA ACUST UNITED AC 2015; 144:41-54. [PMID: 24981229 PMCID: PMC4076524 DOI: 10.1085/jgp.201311145] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Preference for cGMP binding to a cyclic nucleotide–binding domain can achieved by compensating for ligand dehydration or through retention of solvation waters in the bound state. Cyclic nucleotide–binding (CNB) domains regulate the activity of channels, kinases, exchange factors, and transcription factors. These proteins are highly variable in their ligand selectivity; some are highly selective for either cAMP or cGMP, whereas others are not. Several molecular determinants of ligand selectivity in CNB domains have been defined, but these do not provide a complete view of the selectivity mechanism. We performed a thorough analysis of the ligand-binding properties of mutants of the CNB domain from the MlotiK1 potassium channel. In particular, we defined which residues specifically favor cGMP or cAMP. Inversion of ligand selectivity, from favoring cAMP to favoring cGMP, was only achieved through a combination of three mutations in the ligand-binding pocket. We determined the x-ray structure of the triple mutant bound to cGMP and performed molecular dynamics simulations and a biochemical analysis of the effect of the mutations. We concluded that the increase in cGMP affinity and selectivity does not result simply from direct interactions between the nucleotide base and the amino acids introduced in the ligand-binding pocket residues. Rather, tighter cGMP binding over cAMP results from the polar chemical character of the mutations, from greater accessibility of water molecules to the ligand in the bound state, and from an increase in the structural flexibility of the mutated binding pocket.
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Affiliation(s)
- João Pessoa
- Instituto de Biologia Molecular e Celular and Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4150-180 Porto, PortugalInstituto de Biologia Molecular e Celular and Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4150-180 Porto, Portugal
| | - Fátima Fonseca
- Instituto de Biologia Molecular e Celular and Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4150-180 Porto, Portugal
| | - Simone Furini
- Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
| | - João H Morais-Cabral
- Instituto de Biologia Molecular e Celular and Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4150-180 Porto, Portugal
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Yang F, Xiao X, Cheng W, Yang W, Yu P, Song Z, Yarov-Yarovoy V, Zheng J. Structural mechanism underlying capsaicin binding and activation of the TRPV1 ion channel. Nat Chem Biol 2015; 11:518-524. [PMID: 26053297 PMCID: PMC4472570 DOI: 10.1038/nchembio.1835] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 05/01/2015] [Indexed: 11/09/2022]
Abstract
Capsaicin bestows spiciness by activating TRPV1 channel with exquisite potency and selectivity. Although a capsaicin-bound channel structure was previously resolved by cryo-EM at 4.2- to 4.5-Å resolution, capsaicin was registered as a small electron density, reflecting neither its chemical structure nor specific ligand-channel interactions--important details required for mechanistic understanding. We obtained the missing atomic-level details by iterative computation and confirmed them by systematic site-specific functional tests. We observed that the bound capsaicin takes a 'tail-up, head-down' configuration. The vanillyl and amide groups form specific interactions to anchor its bound position, while the aliphatic tail may sample a range of conformations, making it invisible in cryo-EM images. Capsaicin stabilizes TRPV1's open state by 'pull-and-contact' interactions between the vanillyl group and the S4-S5 linker. Our study provides a structural mechanism for the agonistic function of capsaicin and its analogs, and demonstrates an effective approach to obtain atomic-level information from cryo-EM structures.
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Affiliation(s)
- Fan Yang
- Department of Physiology and Membrane Biology, University of California, Davis, California 95616, United States
| | - Xian Xiao
- Department of Physiology and Membrane Biology, University of California, Davis, California 95616, United States
| | - Wei Cheng
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Wei Yang
- Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Peilin Yu
- Department of Toxicology, School of Public health, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Zhenzhen Song
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, Zhejiang 310018, China
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, California 95616, United States
| | - Jie Zheng
- Department of Physiology and Membrane Biology, University of California, Davis, California 95616, United States
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Kohl B, Rothenberg I, Ali SA, Alam M, Seebohm G, Kalbacher H, Voelter W, Stoll R. Solid phase synthesis, NMR structure determination of α-KTx3.8, its in silico docking to Kv1.x potassium channels, and electrophysiological analysis provide insights into toxin-channel selectivity. Toxicon 2015; 101:70-8. [PMID: 25953725 DOI: 10.1016/j.toxicon.2015.04.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/07/2015] [Accepted: 04/29/2015] [Indexed: 12/29/2022]
Abstract
Animal venoms, such as those from scorpions, are a potent source for new pharmacological substances. In this study we have determined the structure of the α-KTx3.8 (named as Bs6) scorpion toxin by multidimensional (1)H homonuclear NMR spectroscopy and investigated its function by molecular dynamics (MD) simulations and electrophysiological measurements. Bs6 is a potent inhibitor of the Kv1.3 channel which plays an important role during the activation and proliferation of memory T-cells (TEM), which play an important role in autoimmune diseases. Therefore, it could be an interesting target for treatment of autoimmune diseases. In this study, Bs6 was synthesised by solid phase synthesis and its three-dimensional (3D) structure has been determined. To gain a deeper insight into the interaction of Bs6 with different potassium channels like hKv1.1 and hKv1.3, the protein-protein complex was modelled based on known toxin-channel structures and tested for stability in MD simulations using GROMACS. The toxin-channel interaction was further analysed by electrophysiological measurements of different potassium channels like hKv1.3 and hKv7.1. As potassium channel inhibitors could play an important role to overcome autoimmune diseases like multiple sclerosis and type-1 diabetes mellitus, our data contributes to the understanding of the molecular mechanism of action and will ultimately help to develop new potent inhibitors in future.
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Affiliation(s)
- Bastian Kohl
- Ruhr University Bochum, Faculty of Chemistry and Biochemistry, Biomolecular Spectroscopy, Ruhr University of Bochum, D-44780 Bochum, Germany
| | - Ina Rothenberg
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, D-48149 Münster, Germany
| | - Syed Abid Ali
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen D-72076, Germany; HEJ Research Institute of Chemistry, ICCBS, University of Karachi, Karachi 75270, Pakistan
| | - Mehtab Alam
- Dow International College, Dow University of Health Sciences, Karachi 75270, Pakistan
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, D-48149 Münster, Germany
| | - Hubert Kalbacher
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen D-72076, Germany
| | - Wolfgang Voelter
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen D-72076, Germany.
| | - Raphael Stoll
- Ruhr University Bochum, Faculty of Chemistry and Biochemistry, Biomolecular Spectroscopy, Ruhr University of Bochum, D-44780 Bochum, Germany.
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45
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Chowdhury S, Haehnel BM, Chanda B. A self-consistent approach for determining pairwise interactions that underlie channel activation. ACTA ACUST UNITED AC 2014; 144:441-55. [PMID: 25311637 PMCID: PMC4210424 DOI: 10.1085/jgp.201411184] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Net free-energy measurements can be combined with mutant cycle analysis to determine interaction energies between specific amino acid pairs during channel activation. Signaling proteins such as ion channels largely exist in two functional forms, corresponding to the active and resting states, connected by multiple intermediates. Multiparametric kinetic models based on sophisticated electrophysiological experiments have been devised to identify molecular interactions of these conformational transitions. However, this approach is arduous and is not suitable for large-scale perturbation analysis of interaction pathways. Recently, we described a model-free method to obtain the net free energy of activation in voltage- and ligand-activated ion channels. Here we extend this approach to estimate pairwise interaction energies of side chains that contribute to gating transitions. Our approach, which we call generalized interaction-energy analysis (GIA), combines median voltage estimates obtained from charge-voltage curves with mutant cycle analysis to ascertain the strengths of pairwise interactions. We show that, for a system with an arbitrary gating scheme, the nonadditive contributions of amino acid pairs to the net free energy of activation can be computed in a self-consistent manner. Numerical analyses of sequential and allosteric models of channel activation also show that this approach can measure energetic nonadditivities even when perturbations affect multiple transitions. To demonstrate the experimental application of this method, we reevaluated the interaction energies of six previously described long-range interactors in the Shaker potassium channel. Our approach offers the ability to generate detailed interaction energy maps in voltage- and ligand-activated ion channels and can be extended to any force-driven system as long as associated “displacement” can be measured.
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Affiliation(s)
- Sandipan Chowdhury
- Graduate Program in Biophysics and Department of Neuroscience, University of Wisconsin, Madison, WI 53705 Graduate Program in Biophysics and Department of Neuroscience, University of Wisconsin, Madison, WI 53705
| | - Benjamin M Haehnel
- Graduate Program in Biophysics and Department of Neuroscience, University of Wisconsin, Madison, WI 53705 Graduate Program in Biophysics and Department of Neuroscience, University of Wisconsin, Madison, WI 53705
| | - Baron Chanda
- Graduate Program in Biophysics and Department of Neuroscience, University of Wisconsin, Madison, WI 53705 Graduate Program in Biophysics and Department of Neuroscience, University of Wisconsin, Madison, WI 53705
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46
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Abstract
Ion channels are essential for basic cellular function and for processes including sensory perception and intercellular communication in multicellular organisms. Voltage-gated potassium (Kv) channels facilitate dynamic cellular repolarization during an action potential, opening in response to membrane depolarization to facilitate K+ efflux. In both excitable and nonexcitable cells other, constitutively active, K+ channels provide a relatively constant repolarizing force to control membrane potential, ion homeostasis, and secretory processes. Of the forty known human Kv channel pore-forming α subunits that coassemble in various combinations to form the fundamental tetrameric channel pore and voltage sensor module, KCNQ1 is unique. KCNQ1 stands alone in having the capacity to form either channels that are voltage-dependent and require membrane depolarization for activation, or constitutively active channels. In mammals, KCNQ1 regulates processes including gastric acid secretion, thyroid hormone biosynthesis, salt and glucose homeostasis, and cell volume and in some species is required for rhythmic beating of the heart. In this review, the author discusses the unique functional properties, regulation, cell biology, diverse physiological roles, and involvement in human disease states of this chameleonic K+ channel.
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47
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Zhu S, Peigneur S, Gao B, Umetsu Y, Ohki S, Tytgat J. Experimental conversion of a defensin into a neurotoxin: implications for origin of toxic function. Mol Biol Evol 2014; 31:546-59. [PMID: 24425781 DOI: 10.1093/molbev/msu038] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Scorpion K(+) channel toxins and insect defensins share a conserved three-dimensional structure and related biological activities (defense against competitors or invasive microbes by disrupting their membrane functions), which provides an ideal system to study how functional evolution occurs in a conserved structural scaffold. Using an experimental approach, we show that the deletion of a small loop of a parasitoid venom defensin possessing the "scorpion toxin signature" (STS) can remove steric hindrance of peptide-channel interactions and result in a neurotoxin selectively inhibiting K(+) channels with high affinities. This insect defensin-derived toxin adopts a hallmark scorpion toxin fold with a common cysteine-stabilized α-helical and β-sheet motif, as determined by nuclear magnetic resonance analysis. Mutations of two key residues located in STS completely diminish or significantly decrease the affinity of the toxin on the channels, demonstrating that this toxin binds to K(+) channels in the same manner as scorpion toxins. Taken together, these results provide new structural and functional evidence supporting the predictability of toxin evolution. The experimental strategy is the first employed to establish an evolutionary relationship of two distantly related protein families.
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Affiliation(s)
- Shunyi Zhu
- Group of Animal Innate Immunity, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, Chaoyang District, Beijing, China
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48
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Abstract
Voltage-gated proton (Hv1) channels play important roles in the respiratory burst, in pH regulation, in spermatozoa, in apoptosis, and in cancer metastasis. Unlike other voltage-gated cation channels, the Hv1 channel lacks a centrally located pore formed by the assembly of subunits. Instead, the proton permeation pathway in the Hv1 channel is within the voltage-sensing domain of each subunit. The gating mechanism of this pathway is still unclear. Mutagenic and fluorescence studies suggest that the fourth transmembrane (TM) segment (S4) functions as a voltage sensor and that there is an outward movement of S4 during channel activation. Using thermodynamic mutant cycle analysis, we find that the conserved positively charged residues in S4 are stabilized by countercharges in the other TM segments both in the closed and open states. We constructed models of both the closed and open states of Hv1 channels that are consistent with the mutant cycle analysis. These structural models suggest that electrostatic interactions between TM segments in the closed state pull hydrophobic residues together to form a hydrophobic plug in the center of the voltage-sensing domain. Outward S4 movement during channel activation induces conformational changes that remove this hydrophobic plug and instead insert protonatable residues in the center of the channel that, together with water molecules, can form a hydrogen bond chain across the channel for proton permeation. This suggests that salt bridge networks and the hydrophobic plug function as the gate in Hv1 channels and that outward movement of S4 leads to the opening of this gate.
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49
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Characterization of the first K+ channel blockers from the venom of the Moroccan scorpion Buthus occitanus Paris. Toxicon 2013; 75:168-76. [DOI: 10.1016/j.toxicon.2013.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 02/27/2013] [Accepted: 03/06/2013] [Indexed: 11/22/2022]
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50
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Demers-Giroux PO, Bourdin B, Sauvé R, Parent L. Cooperative activation of the T-type CaV3.2 channel: interaction between Domains II and III. J Biol Chem 2013; 288:29281-93. [PMID: 23970551 PMCID: PMC3795230 DOI: 10.1074/jbc.m113.500975] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 08/02/2013] [Indexed: 12/28/2022] Open
Abstract
T-type CaV3 channels are important mediators of Ca(2+) entry near the resting membrane potential. Little is known about the molecular mechanisms responsible for channel activation. Homology models based upon the high-resolution structure of bacterial NaV channels predict interaction between the S4-S5 helix of Domain II (IIS4-S5) and the distal S6 pore region of Domain II (IIS6) and Domain III (IIIS6). Functional intra- and inter-domain interactions were investigated with a double mutant cycle analysis. Activation gating and channel kinetics were measured for 47 single mutants and 20 pairs of mutants. Significant coupling energies (ΔΔG(interact) ≥ 1.5 kcal mol(-1)) were measured for 4 specific pairs of mutants introduced between IIS4-S5 and IIS6 and between IIS4-S5 and IIIS6. In agreement with the computer based models, Thr-911 in IIS4-S5 was functionally coupled with Ile-1013 in IIS6 during channel activation. The interaction energy was, however, found to be stronger between Val-907 in IIS4-S5 and Ile-1013 in IIS6. In addition Val-907 was significantly coupled with Asn-1548 in IIIS6 but not with Asn-1853 in IVS6. Altogether, our results demonstrate that the S4-S5 and S6 helices from adjacent domains are energetically coupled during the activation of a low voltage-gated T-type CaV3 channel.
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Affiliation(s)
- Pierre-Olivier Demers-Giroux
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Benoîte Bourdin
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Rémy Sauvé
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Lucie Parent
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
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