1bmr
ALPHA-LIKE TOXIN LQH III FROM SCORPION LEIURUS QUINQUESTRIATUS HEBRAEUS, NMR, 25 STRUCTURES
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OverviewOverview
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.
About this StructureAbout this Structure
1BMR is a Single protein structure of sequence from Leiurus quinquestriatus hebraeus with NH2 as ligand. Full crystallographic information is available from OCA.
ReferenceReference
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 JM, J Mol Biol. 1999 Jan 29;285(4):1749-63. PMID:9917409
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