{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,12]],"date-time":"2026-07-12T10:06:24Z","timestamp":1783850784759,"version":"3.55.0"},"reference-count":32,"publisher":"Portland Press Ltd.","issue":"1","content-domain":{"domain":["portlandpress.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2005,5,15]]},"abstract":"<jats:p>The Om-toxins are short peptides (23\u201327 amino acids) purified from the venom of the scorpion Opisthacanthus madagascariensis. Their pharmacological targets are thought to be potassium channels. Like Cs\u03b1\/\u03b2 (cystine-stabilized \u03b1\/\u03b2) toxins, the Om-toxins alter the electrophysiological properties of these channels; however, they do not share any sequence similarity with other scorpion toxins. We herein demonstrate by electrophysiological experiments that Om-toxins decrease the amplitude of the K+ current of the rat channels Kv1.1 and Kv1.2, as well as human Kv1.3. We also determine the solution structure of three of the toxins by use of two-dimensional proton NMR techniques followed by distance geometry and molecular dynamics. The structures of these three peptides display an uncommon fold for ion-channel blockers, Cs\u03b1\/\u03b1 (cystine-stabilized \u03b1-helix\u2013loop\u2013helix), i.e. two \u03b1-helices connected by a loop and stabilized by two disulphide bridges. We compare the structures obtained and the dipole moments resulting from the electrostatic anisotropy of these peptides with those of the only other toxin known to share the same fold, namely \u03ba-hefutoxin1.<\/jats:p>","DOI":"10.1042\/bj20041705","type":"journal-article","created":{"date-parts":[[2005,5,10]],"date-time":"2005-05-10T16:27:42Z","timestamp":1115742462000},"page":"263-271","update-policy":"https:\/\/doi.org\/10.1042\/crossmark_policy","source":"Crossref","is-referenced-by-count":75,"title":["An unusual fold for potassium channel blockers: NMR structure of three toxins from the scorpion <i>Opisthacanthus madagascariensis<\/i>"],"prefix":"10.1042","volume":"388","author":[{"given":"Benjamin","family":"CHAGOT","sequence":"first","affiliation":[{"name":"Architecture et Fonction des Macromol\u00e9cules Biologiques, UMR 6098, CNRS et Universit\u00e9s d'Aix-Marseille I et II, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cyril","family":"PIMENTEL","sequence":"additional","affiliation":[{"name":"Architecture et Fonction des Macromol\u00e9cules Biologiques, UMR 6098, CNRS et Universit\u00e9s d'Aix-Marseille I et II, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"DAI","sequence":"additional","affiliation":[{"name":"Department of Entomology, University of California, Riverside, Riverside, CA 92521, U.S.A."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joost","family":"PIL","sequence":"additional","affiliation":[{"name":"Laboratory of Toxicology, University of Leuven, E, Van Evenstraat 4, B-3000 Leuven, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan","family":"TYTGAT","sequence":"additional","affiliation":[{"name":"Laboratory of Toxicology, University of Leuven, E, Van Evenstraat 4, B-3000 Leuven, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Terumi","family":"NAKAJIMA","sequence":"additional","affiliation":[{"name":"Suntory Institute for Bioorganic Research, Mishima-Gun, Shimamoto-Cho, Wakayamadai 1-1-1, Osaka 618-8503, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gerardo","family":"CORZO","sequence":"additional","affiliation":[{"name":"Suntory Institute for Bioorganic Research, Mishima-Gun, Shimamoto-Cho, Wakayamadai 1-1-1, Osaka 618-8503, Japan"},{"name":"Department of Molecular Recognition and Structural Biology, Institute of Biotechnology, Av. Universidad, Cuernavaca, Morelos, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Herv\u00e9","family":"DARBON","sequence":"additional","affiliation":[{"name":"Architecture et Fonction des Macromol\u00e9cules Biologiques, UMR 6098, CNRS et Universit\u00e9s d'Aix-Marseille I et II, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gilles","family":"FERRAT","sequence":"additional","affiliation":[{"name":"Architecture et Fonction des Macromol\u00e9cules Biologiques, UMR 6098, CNRS et Universit\u00e9s d'Aix-Marseille I et II, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France"},{"name":"Suntory Institute for Bioorganic Research, Mishima-Gun, Shimamoto-Cho, Wakayamadai 1-1-1, Osaka 618-8503, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"288","published-online":{"date-parts":[[2005,5,10]]},"reference":[{"key":"2021112213195583300_B1","doi-asserted-by":"crossref","first-page":"1521","DOI":"10.1126\/science.1720574","article-title":"Refined structure of charybdotoxin: common motifs in scorpion toxins and insect defensins","volume":"254","author":"Bontems","year":"1991","journal-title":"Science"},{"key":"2021112213195583300_B2","doi-asserted-by":"crossref","first-page":"12412","DOI":"10.1021\/bi9809371","article-title":"Solution structure of two new toxins from the venom of the Chinese scorpion Buthus martensi Karsch blockers of potassium channels","volume":"37","author":"Blanc","year":"1998","journal-title":"Biochemistry"},{"key":"2021112213195583300_B3","doi-asserted-by":"crossref","first-page":"13605","DOI":"10.1074\/jbc.275.18.13605","article-title":"Synthesis, 1H NMR structure, and activity of a three-disulfide-bridged maurotoxin analog designed to restore the consensus motif of scorpion toxins","volume":"275","author":"Fajloun","year":"2000","journal-title":"J. Biol. Chem."},{"key":"2021112213195583300_B4","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1002\/(SICI)1097-0134(20000101)38:1<70::AID-PROT8>3.0.CO;2-5","article-title":"Solution structure of BmKTX, a K+ blocker toxin from the Chinese scorpion Buthus martensi","volume":"38","author":"Renisio","year":"2000","journal-title":"Proteins"},{"key":"2021112213195583300_B5","doi-asserted-by":"crossref","first-page":"1833","DOI":"10.1002\/pro.5560031022","article-title":"A common structural motif incorporating a cystine knot and a triple-stranded beta-sheet in toxic and inhibitory polypeptides","volume":"3","author":"Pallaghy","year":"1994","journal-title":"Protein Sci."},{"key":"2021112213195583300_B6","doi-asserted-by":"crossref","first-page":"1573","DOI":"10.1016\/S0041-0101(98)00149-4","article-title":"The cystine knot structure of ion channel toxins and related polypeptides","volume":"36","author":"Norton","year":"1998","journal-title":"Toxicon"},{"key":"2021112213195583300_B7","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1016\/S0041-0101(00)00160-4","article-title":"The cystine knot motif in toxins and implications for drug design","volume":"39","author":"Craik","year":"2001","journal-title":"Toxicon"},{"key":"2021112213195583300_B8","first-page":"2059","article-title":"Solution structure of hpTX2, a toxin from Heteropoda venatoria spider that blocks Kv4.2 potassium channel","volume":"9","author":"Bernard","year":"2000","journal-title":"Protein Sci."},{"key":"2021112213195583300_B9","doi-asserted-by":"crossref","first-page":"436","DOI":"10.1002\/1097-0134(20000815)40:3<436::AID-PROT90>3.0.CO;2-9","article-title":"A new fold in the scorpion toxin family, associated with an activity on a ryanodine-sensitive calcium channel","volume":"40","author":"Mosbah","year":"2000","journal-title":"Proteins"},{"key":"2021112213195583300_B10","doi-asserted-by":"crossref","first-page":"30040","DOI":"10.1074\/jbc.M111258200","article-title":"\u03ba-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with a unique structure and function: importance of the functional diad in potassium channel selectivity","volume":"277","author":"Srinivasan","year":"2002","journal-title":"J. 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Commun."},{"key":"2021112213195583300_B14","doi-asserted-by":"crossref","first-page":"661","DOI":"10.1007\/BF02192855","article-title":"Gradient-tailored excitation for single-quantum NMR spectroscopy of aqueous solutions","volume":"2","author":"Piotto","year":"1992","journal-title":"J. Biomol. NMR"},{"key":"2021112213195583300_B15","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/BF00417486","article-title":"The program XEASY for computer-supported NMR spectral analysis of biological macromolecules","volume":"5","author":"Bartels","year":"1995","journal-title":"J. Biomol. 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Res."},{"key":"2021112213195583300_B18","doi-asserted-by":"crossref","first-page":"12795","DOI":"10.1021\/bi015537j","article-title":"Solution structure of Ptu1, a toxin from the assassin bug Peirates turpis that blocks the voltage-sensitive calcium channel N-type","volume":"40","author":"Bernard","year":"2001","journal-title":"Biochemistry"},{"key":"2021112213195583300_B19","doi-asserted-by":"crossref","first-page":"10998","DOI":"10.1021\/bi010228e","article-title":"Structural basis for alpha-K toxin specificity for K+ channels revealed through the solution 1H NMR structures of two noxiustoxin-iberiotoxin chimeras","volume":"40","author":"Ferrat","year":"2001","journal-title":"Biochemistry"},{"key":"2021112213195583300_B20","doi-asserted-by":"crossref","first-page":"905","DOI":"10.1107\/S0907444998003254","article-title":"Crystallography & NMR system: a new software suite for macromolecular structure determination","volume":"54","author":"Brunger","year":"1998","journal-title":"Acta Crystallogr. D Biol. Crystallogr."},{"key":"2021112213195583300_B21","first-page":"77","article-title":"Silicon Graphics Geometry Partner Directory","author":"Roussel","year":"1989"},{"key":"2021112213195583300_B22","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/0263-7855(96)00009-4","article-title":"MOLMOL: a program for display and analysis of macromolecular structures","volume":"14","author":"Koradi","year":"1996","journal-title":"J. Mol. Graphics"},{"key":"2021112213195583300_B23","doi-asserted-by":"crossref","first-page":"477","DOI":"10.1007\/BF00228148","article-title":"AQUA and PROCHECK-NMR: programs for checking the quality of protein structures solved by NMR","volume":"8","author":"Laskowski","year":"1996","journal-title":"J. Biomol. 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Crystallogr."},{"key":"2021112213195583300_B25","doi-asserted-by":"crossref","first-page":"505","DOI":"10.1016\/S0076-6879(97)77028-9","article-title":"Raster3D: photorealistic molecular graphics","volume":"277","author":"Merritt","year":"1997","journal-title":"Methods Enzymol."},{"key":"2021112213195583300_B26","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1002\/prot.340110407","article-title":"Protein folding and association: insights from the interfacial and thermodynamic properties of hydrocarbons","volume":"11","author":"Nicholls","year":"1991","journal-title":"Proteins"},{"key":"2021112213195583300_B27","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1002\/jcc.540120405","article-title":"A rapid finite difference algorithm, utililizing successive over-relaxation to solve the Poisson-Boltzman equation","volume":"12","author":"Nicholls","year":"1991","journal-title":"J. Comput. Chem."},{"key":"2021112213195583300_B28","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1002\/prot.10513","article-title":"Solution structure of ADO1, a toxin extracted from the saliva of the assassin bug, Agriosphodrus dohrni","volume":"54","author":"Bernard","year":"2004","journal-title":"Proteins"},{"key":"2021112213195583300_B29","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1007\/BF02192866","article-title":"Improved efficiency of protein structure calculations from NMR data using the program DIANA with redundant dihedral angle constraints","volume":"1","author":"Guntert","year":"1991","journal-title":"J. Biomol. 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