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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/13605

Title: Purification, molecular cloning and functional characterization of HelaTx1 (Heterometrus laoticus): The first member of a new kappa-KTX subfamily
Authors: Vandendriessche, Thomas
Kopljar, Ivan
Jenkins, David Paul
Diego-Garcia, Elia
Abdel-Mottaleb, Yousra
Vermassen, Elke
Schoofs, Liliane
Wulff, Heike
Snyders, Dirk
Tytgat, Jan
Issue Date: 2012
Citation: BIOCHEMICAL PHARMACOLOGY, 83 (9), p. 1307-1317
Abstract: Given their medical importance, most attention has been paid toward the venom composition of scorpions of the Buthidae family. Nevertheless, research has shown that the venom of scorpions of other families is also a remarkable source of unique peptidyl toxins. The kappa-KTx family of voltage-gated potassium channel (VGPC) scorpion toxins is hereof an example. From the telson of the scorpion Heterometrus laoticus (Scorpionidae), a peptide, HelaTx1, with unique primary sequence was purified through HPLC and sequenced by Edman degradation. Based on the amino acid sequence, the peptide could be cloned and the cDNA sequence revealed. HelaTx1 was chemically synthesized and functionally characterized on VGPCs of the Shaker-related, Shab-related, Shaw-related and Shal-related subfamilies. Furthermore, the toxin was also tested on small- and intermediate conductance Ca2+-activated K+ channels. From the channels studied, K(v)1.1 and K(v)1.6 were found to be the most sensitive (K(v)1.1 EC50 = 9.9 +/- 1.6 mu M). The toxin did not alter the activation of the channels. Competition experiments with TEA showed that the toxin is a pore blocker. Mutational studies showed that the residues E353 and Y379 in the pore of K(v)1.1 act as major interaction points for binding of the toxin. Given the amino acid sequence, the predicted secondary structure and the biological activity on VGPCs, HelaTx1 should be included in the kappa-KTX family. Based on a phylogenetic study, we rearranged this family of VGPC toxins into five subfamilies and suggest that HelaTx1 is the first member of the new kappa-KTx5 subfamily. (C) 2012 Elsevier Inc. All rights reserved.
Notes: Tytgat, J (reprint author),Katholieke Univ Leuven, Toxicol Lab, Onderwijs & Navorsing 2,POB 922,Herestr 49, B-3000 Louvain, Belgium. [Vandendriessche, Thomas; Diego-Garcia, Elia; Abdel-Mottaleb, Yousra; Vermassen, Elke; Tytgat, Jan] Katholieke Univ Leuven, Toxicol Lab, B-3000 Louvain, Belgium. [Kopljar, Ivan; Snyders, Dirk] Univ Antwerp, Lab Mol Biophys Physiol & Pharmacol, B-2610 Antwerp, Belgium. [Jenkins, David Paul; Wulff, Heike] Univ Calif Davis, Dept Pharmacol, Davis, CA 95616 USA. [Clynen, Elke; Schoofs, Liliane] Katholieke Univ Leuven, Res Grp Funct Genom & Prote, B-3000 Louvain, Belgium. [Clynen, Elke] Univ Hasselt, Biomed Res Inst, B-3590 Diepenbeek, Belgium. Jan.Tytgat@pharm.kuleuven.be
URI: http://hdl.handle.net/1942/13605
DOI: 10.1016/j.bcp.2012.01.021
ISI #: 000301906900018
ISSN: 0006-2952
Category: A1
Type: Journal Contribution
Validation: ecoom, 2013
Appears in Collections: Research publications

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