Solution structure and functional analysis of HelaTx1: the first toxin member of the -KTx5 subfamily
1
조회
0
다운로드
0
인용
0
참고문헌
키워드
초록
Scorpion venom comprises a cocktail of toxins that have proven to be useful molecular tools for studying the pharmacological properties of membrane ion channels. HelaTx1, a short peptide neurotoxin isolated recently from the venom of the scorpion Heterometrus laoticus, is a 25 amino acid peptide with two disulfide bonds that shares low sequence homology with other scorpion toxins. HelaTx1 effectively decreases the amplitude of the K+ currents of voltage-gated Kv1.1 and Kv1.6 channels expressed in Xenopus oocytes, and was identified as the first toxin member of the -KTx5 subfamily, based on a sequence comparison and phylogenetic analysis. In the present study, we report the NMR solution structure of HelaTx1, and the major interaction points for its binding to voltage-gated Kv1.1 channels. The NMR results indicate that HelaTx1 adopts a helix-loop-helix fold linked by two disulfide bonds without any -sheets, resembling the molecular folding of other cysteine-stabilized helix-loop-helix (Cs /) scorpion toxins such as -hefutoxin, HeTx, and OmTx, as well as conotoxin pl14a. A series of alanine-scanning analogs revealed a broad surface on the toxin molecule largely comprising positively- charged residues that is crucial for interaction with voltagegated Kv1.1 channels. Interestingly, the functional dyad, a key molecular determinant for activity against voltage-gated potassium channels in other toxins, is not present in HelaTx1.
Abstract
Scorpion venom comprises a cocktail of toxins that have proven to be useful molecular tools for studying the pharmacological properties of membrane ion channels. HelaTx1, a short peptide neurotoxin isolated recently from the venom of the scorpion Heterometrus laoticus, is a 25 amino acid peptide with two disulfide bonds that shares low sequence homology with other scorpion toxins. HelaTx1 effectively decreases the amplitude of the K+ currents of voltage-gated Kv1.1 and Kv1.6 channels expressed in Xenopus oocytes, and was identified as the first toxin member of the -KTx5 subfamily, based on a sequence comparison and phylogenetic analysis. In the present study, we report the NMR solution structure of HelaTx1, and the major interaction points for its binding to voltage-gated Kv1.1 channels. The NMR results indicate that HelaTx1 adopts a helix-loop-helix fold linked by two disulfide bonds without any -sheets, resembling the molecular folding of other cysteine-stabilized helix-loop-helix (Cs /) scorpion toxins such as -hefutoxin, HeTx, and OmTx, as well as conotoxin pl14a. A series of alanine-scanning analogs revealed a broad surface on the toxin molecule largely comprising positively- charged residues that is crucial for interaction with voltagegated Kv1.1 channels. Interestingly, the functional dyad, a key molecular determinant for activity against voltage-gated potassium channels in other toxins, is not present in HelaTx1.
참고문헌 (25)
- Gwee MC, "Autonomic effects of some scorpion venoms and toxins", Clin Exp Pharmacol Physiol, 29, pp.795~801 (2002)
- Chandy KG, "K+ channels as targets for specific immunomodulation", Trends Pharmacol Sci, 25, pp.280~289 (2004)
- Rodriguez de la Vega RC, "Current views on scorpion toxins specific for K+-channels", Toxicon, 43, pp.865~875 (2004)
- Rodriguez de la Vega RC, "Overview of scorpion toxins specific for Na+ channels and related peptides : biodiversity, structure-function relationships and evolution", Toxicon, 46, pp.831~844 (2005)
- Quintero-Hernandez V, "Scorpion venom components that affect ion-channels function", Toxicon, 76, pp.328~342 (2013)
- Ortiz E, "Scorpion venom components as potential candidates for drug development", Toxicon, 93, pp.125~135 (2015)
- Zhu S, "Molecular diversity and functional evolution of scorpion potassium channel toxins", Mol Cell Proteomics, 10, pp.M110002832~ (2011)
- Vandendriessche T, "Purification, molecular cloning and functional characterization of HelaTx1(Heterometrus laoticus) : the first member of a new kappa-KTX subfamily", Biochem Pharmacol, 83, pp.1307~1317 (2012)
- Mouhat S, "Contribution of the functional dyad of animal toxins acting on voltage-gated Kv1-type channels", J Pept Sci, 11, pp.65~68 (2005)
- Peigneur S, "Effects of deletion and insertion of amino acids on the activity of HelaTx1, a scorpion toxin on potassium channels", Toxicon, 111, pp.1~5 (2016)
- Al-Sabi A, "Arrangement of Kv1 alpha subunits dictates sensitivity to tetraethylammonium", J Gen Physiol, 136, pp.273~282 (2010)
- Gao B, "Functional evolution of scorpion venom peptides with an inhibitor cystine knot fold", Biosci Rep, 33, pp.pii:e00047~ (2013)
- Srinivasan KN, "kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity", J Biol Chem, 277, pp.30040~30047 (2002)
- Chagot B, "An unusual fold for potassium channel blockers : NMR structure of three toxins from the scorpion Opisthacanthus madagascariensis", Biochem J, 388, pp.263~271 (2005)
- Chen ZY, "Structural and functional diversity of acidic scorpion potassium channel toxins", PLoS One, 7, pp.e35154~ (2012)
- Imperial JS, "A novel conotoxin inhibitor of Kv1. 6 channel and nAChR subtypes defines a new superfamily of conotoxins", Biochemistry, 45, pp.8331~8340 (2006)
- Mouhat S, "Diversity of folds in animal toxins acting on ion channels", Biochem J, 378, pp.717~726 (2004)
- Moller C, "A novel conotoxin framework with a helix-loop-helix(Cs alpha", alpha)fold, 2005, pp.44, 15986~15996
- MacKinnon R, "Charybdotoxin block of Shaker K+ channels suggests that different types of K+ channels share common structural features", Neuron, 1, pp.997~1001 (1988)
- Li-Smerin Y, "Localization and molecular determinants of the Hanatoxin receptors on the voltage-sensing domains of a K(+)channel", J Gen Physiol, 115, pp.673~684 (2000)
- Mouhat S, "The 'functional' dyad of scorpion toxin Pi1 is not itself a prerequisite for toxin binding to the voltage-gated Kv1. 2potassium channels", Biochem J, 377, pp.25~36 (2004)
- Badger J, "New features and enhancements in the X-PLOR computer program", Proteins, 35, pp.25~33 (1999)
- Rasar MA, "The physiology of the Xenopus laevis ovary", Methods Mol Biol, 322, pp.17~30 (2006)
- Abdel-Mottaleb Y, "A common “hot spot” confers hERG blockade activity to alpha-scorpion toxins affecting K+ channels", Biochem Pharmacol, 76, pp.805~815 (2008)
- Orts DJ, "Biochemical and electrophysiological characterization of two sea anemone type 1 potassium toxins from a geographically distant population of Bunodosoma caissarum", Mar Drugs, 11, pp.655~679 (2013)