NMR structures and activity of a novel alpha-like toxin from the scorpion Leiurus quinquestriatus hebraeus.Krimm, I., Gilles, N., Sautiere, P., Stankiewicz, M., Pelhate, M., Gordon, D., Lancelin, J.M.
(1999) J.Mol.Biol. 285: 1749-1763
- PubMed: 9917409
- DOI: 10.1006/jmbi.1998.2418
- PubMed Abstract:
- Sodium Channels as Targets for Neurotoxins. Modes of Action and Interaction of Neurotoxins with Receptor Sites on Sodium Channels
(1997) Toxins and Signal Transduction (in: Cellular and Molecular Mechanisms of Toxin Action, V.1) --: 119
- New Toxins Acting on Sodium Channels from the Scorpion Leiurus Quinquestriatus Hebraeus Suggest a Clue to Mammalian Vs Insect Selectivity
Sautiere, P.,Cestele, S.,Kopeyan, C.,Martinage, A.,Drobecq, H.,Doljansky, Y.,Gordon, D.
(1998) Toxicon 36: 1141
NMR structures of a new toxin from the scorpion Leiurus quinquestriatus hebraeus (Lqh III) have been investigated in conjunction with its pharmacological properties. This toxin is proposed to belong to a new group of scorpion toxins, the alpha-like t ...
NMR structures of a new toxin from the scorpion Leiurus quinquestriatus hebraeus (Lqh III) have been investigated in conjunction with its pharmacological properties. This toxin is proposed to belong to a new group of scorpion toxins, the alpha-like toxins that target voltage-gated sodium channels with specific properties compared with the classical alpha-scorpion toxins. Electrophysiological analysis showed that Lqh III inhibits a sodium current inactivation in the cockroach axon, but induces in addition a resting depolarization due to a slowly decaying tail current atypical to other alpha-toxin action. Binding studies indicated that radiolabeled Lqh III binds with a high degree of affinity (Ki=2.2 nM) on cockroach sodium channels and that the alpha-toxin from L quinquestriatus hebraeus highly active on insects (LqhalphaIT) and alpha-like toxins compete at low concentration for its receptor binding site, suggesting that the alpha-like toxin receptor site is partially overlapping with the receptor site 3. Conversely, in rat brain, Lqh III competes for binding of the most potent anti-mammal alpha-toxin from Androctonus australis Hector venom (AaH II) only at very high concentration. The NMR structures were used for the scrutiny of the similarities and differences with representative scorpion alpha-toxins targeting the voltage-gated sodium channels of either mammals or insects. Three turn regions involved in the functional binding site of the anti-insect LqhalphaIT toxin reveal significant differences in the Lqh III structure. The electrostatic charge distribution in the Lqh III toxin is also surprisingly different when compared with the anti-mammal alpha-toxin AaH II. Similarities in the electrostatic charge distribution are, however, recognized between alpha-toxins highly active on insects and the alpha-like toxin Lqh III. This affords additional important elements to the definition of the new alpha-like group of scorpion toxins and the mammal versus insect scorpion toxin selectivities.
Laboratoire de RMN Biomoléculaire Associé au CNRS, Université Claude Bernard - Lyon 1 et CPE-Lyon, Villeurbanne, France.