| Structural highlights
Function
[TXH4_CYRSC] This lethal neurotoxin (without cyclization at position 53) inhibits neuronal voltage-gated sodium channel Nav1.2/SCN2A (IC(50)=10-150 nM), rNav1.3/SCN3A (IC(50)=338 nM), Nav1.6/SCN8A (IC(50)=117 nM), and hNav1.7/SCN9A (IC(50)=9.6-33 nM) (PubMed:18628201, PubMed:20855463, PubMed:25658507, PubMed:29703751,PubMed:31234412, PubMed:23760503). It inhibits activation of sodium channel by trapping the voltage sensor of domain II (DIIS4) in the closed configuration (PubMed:18628201, PubMed:23760503). The toxin neither shifts the Nav1.7/SCN9A activation curve nor modifies the slope factor (PubMed:20855463). It does not slow fast-inactivation of hNav1.7/SCN9A channels (PubMed:20855463). In addition, it has only a weak affinity for lipid membranes (PubMed:18054060, PubMed:29703751, PubMed:28115115). This toxin also exists with a pyroglutamate at position 53 (PubMed:23826086). The sole difference observed between modified (mHwTx-IV) and unmodified toxins is that moderate or high depolarization voltages (200 mV) permit the unmodified toxin to dissociate, whereas mHwTx-IV toxin does not dissociate, even at high depolarization voltages (PubMed:23826086). These data indicate that mHwTx-IV strongly binds to voltage sensor of sodium channel even at extreme depolarization voltages (PubMed:23826086).[1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
Publication Abstract from PubMed
NaChBac, the first bacterial voltage-gated Na(+) (Nav) channel to be characterized, has been the prokaryotic prototype for studying the structure-function relationship of Nav channels. Discovered nearly two decades ago, the structure of NaChBac has not been determined. Here we present the single particle electron cryomicroscopy (cryo-EM) analysis of NaChBac in both detergent micelles and nanodiscs. Under both conditions, the conformation of NaChBac is nearly identical to that of the potentially inactivated NavAb. Determining the structure of NaChBac in nanodiscs enabled us to examine gating modifier toxins (GMTs) of Nav channels in lipid bilayers. To study GMTs in mammalian Nav channels, we generated a chimera in which the extracellular fragment of the S3 and S4 segments in the second voltage-sensing domain from Nav1.7 replaced the corresponding sequence in NaChBac. Cryo-EM structures of the nanodisc-embedded chimera alone and in complex with HuwenToxin IV (HWTX-IV) were determined to 3.5 and 3.2 A resolutions, respectively. Compared to the structure of HWTX-IV-bound human Nav1.7, which was obtained at an overall resolution of 3.2 A, the local resolution of the toxin has been improved from approximately 6 to approximately 4 A. This resolution enabled visualization of toxin docking. NaChBac can thus serve as a convenient surrogate for structural studies of the interactions between GMTs and Nav channels in a membrane environment.
Employing NaChBac for cryo-EM analysis of toxin action on voltage-gated Na(+) channels in nanodisc.,Gao S, Valinsky WC, On NC, Houlihan PR, Qu Q, Liu L, Pan X, Clapham DE, Yan N Proc Natl Acad Sci U S A. 2020 Jun 23;117(25):14187-14193. doi:, 10.1073/pnas.1922903117. Epub 2020 Jun 8. PMID:32513729[11]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Peng K, Shu Q, Liu Z, Liang S. Function and solution structure of huwentoxin-IV, a potent neuronal tetrodotoxin (TTX)-sensitive sodium channel antagonist from Chinese bird spider Selenocosmia huwena. J Biol Chem. 2002 Dec 6;277(49):47564-71. Epub 2002 Sep 11. PMID:12228241 doi:10.1074/jbc.M204063200
- ↑ Xiao Y, Luo X, Kuang F, Deng M, Wang M, Zeng X, Liang S. Synthesis and characterization of huwentoxin-IV, a neurotoxin inhibiting central neuronal sodium channels. Toxicon. 2008 Feb;51(2):230-9. doi: 10.1016/j.toxicon.2007.09.008. Epub 2007 Sep , 29. PMID:18054060 doi:http://dx.doi.org/10.1016/j.toxicon.2007.09.008
- ↑ Xiao Y, Bingham JP, Zhu W, Moczydlowski E, Liang S, Cummins TR. Tarantula huwentoxin-IV inhibits neuronal sodium channels by binding to receptor site 4 and trapping the domain ii voltage sensor in the closed configuration. J Biol Chem. 2008 Oct 3;283(40):27300-13. doi: 10.1074/jbc.M708447200. Epub 2008 , Jul 14. PMID:18628201 doi:10.1074/jbc.M708447200
- ↑ Xiao Y, Blumenthal K, Jackson JO 2nd, Liang S, Cummins TR. The tarantula toxins ProTx-II and huwentoxin-IV differentially interact with human Nav1.7 voltage sensors to inhibit channel activation and inactivation. Mol Pharmacol. 2010 Dec;78(6):1124-34. doi: 10.1124/mol.110.066332. Epub 2010 Sep, 20. PMID:20855463 doi:http://dx.doi.org/10.1124/mol.110.066332
- ↑ Xiao Y, Jackson JO 2nd, Liang S, Cummins TR. Common molecular determinants of tarantula huwentoxin-IV inhibition of Na+ channel voltage sensors in domains II and IV. J Biol Chem. 2011 Aug 5;286(31):27301-10. doi: 10.1074/jbc.M111.246876. Epub 2011, Jun 9. PMID:21659528 doi:http://dx.doi.org/10.1074/jbc.M111.246876
- ↑ Revell JD, Lund PE, Linley JE, Metcalfe J, Burmeister N, Sridharan S, Jones C, Jermutus L, Bednarek MA. Potency optimization of Huwentoxin-IV on hNav1.7: a neurotoxin TTX-S sodium-channel antagonist from the venom of the Chinese bird-eating spider Selenocosmia huwena. Peptides. 2013 Jun;44:40-6. doi: 10.1016/j.peptides.2013.03.011. Epub 2013 Mar, 19. PMID:23523779 doi:http://dx.doi.org/10.1016/j.peptides.2013.03.011
- ↑ Minassian NA, Gibbs A, Shih AY, Liu Y, Neff RA, Sutton SW, Mirzadegan T, Connor J, Fellows R, Husovsky M, Nelson S, Hunter MJ, Flinspach M, Wickenden AD. Analysis of the Structural and Molecular Basis of Voltage-sensitive Sodium Channel Inhibition by the Spider Toxin Huwentoxin-IV (mu-TRTX-Hh2a). J Biol Chem. 2013 Aug 2;288(31):22707-20. doi: 10.1074/jbc.M113.461392. Epub 2013, Jun 12. PMID:23760503 doi:10.1074/jbc.M113.461392
- ↑ Murray JK, Ligutti J, Liu D, Zou A, Poppe L, Li H, Andrews KL, Moyer BD, McDonough SI, Favreau P, Stocklin R, Miranda LP. Engineering potent and selective analogues of GpTx-1, a tarantula venom peptide antagonist of the Na(V)1.7 sodium channel. J Med Chem. 2015 Mar 12;58(5):2299-314. doi: 10.1021/jm501765v. Epub 2015 Feb 19. PMID:25658507 doi:http://dx.doi.org/10.1021/jm501765v
- ↑ Agwa AJ, Lawrence N, Deplazes E, Cheneval O, Chen RM, Craik DJ, Schroeder CI, Henriques ST. Spider peptide toxin HwTx-IV engineered to bind to lipid membranes has an increased inhibitory potency at human voltage-gated sodium channel hNaV1.7. Biochim Biophys Acta. 2017 Jan 20;1859(5):835-844. doi:, 10.1016/j.bbamem.2017.01.020. PMID:28115115 doi:http://dx.doi.org/10.1016/j.bbamem.2017.01.020
- ↑ Correnti CE, Gewe MM, Mehlin C, Bandaranayake AD, Johnsen WA, Rupert PB, Brusniak MY, Clarke M, Burke SE, De Van Der Schueren W, Pilat K, Turnbaugh SM, May D, Watson A, Chan MK, Bahl CD, Olson JM, Strong RK. Screening, large-scale production and structure-based classification of cystine-dense peptides. Nat Struct Mol Biol. 2018 Mar;25(3):270-278. doi: 10.1038/s41594-018-0033-9. Epub, 2018 Feb 26. PMID:29483648 doi:http://dx.doi.org/10.1038/s41594-018-0033-9
- ↑ Gao S, Valinsky WC, On NC, Houlihan PR, Qu Q, Liu L, Pan X, Clapham DE, Yan N. Employing NaChBac for cryo-EM analysis of toxin action on voltage-gated Na(+) channels in nanodisc. Proc Natl Acad Sci U S A. 2020 Jun 23;117(25):14187-14193. doi:, 10.1073/pnas.1922903117. Epub 2020 Jun 8. PMID:32513729 doi:http://dx.doi.org/10.1073/pnas.1922903117
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