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Function and solution structure of hainantoxin‐I, a novel insect sodium channel inhibitor from the Chinese bird spider Selenocosmia hainana 1
Author(s) -
Li Dongling,
Xiao Yucheng,
Hu Weijun,
Xie Jinyun,
Bosmans Frank,
Tytgat Jan,
Liang Songping
Publication year - 2003
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)01303-6
Subject(s) - spider toxin , sodium channel , spider , venom , stereochemistry , chemistry , xenopus , sodium , insect , biophysics , biochemistry , biology , receptor , botany , zoology , organic chemistry , glutamate receptor , gene
Hainantoxin‐I is a novel peptide toxin, purified from the venom of the Chinese bird spider Selenocosmia hainana (= Ornithoctonus hainana ). It includes 33 amino acid residues with a disulfide linkage of I–IV, II–V and III–VI, assigned by partial reduction and sequence analysis. Under two‐electrode voltage‐clamp conditions, hainantoxin‐I can block rNa v 1.2/β 1 and the insect sodium channel para/tipE expressed in Xenopus laevis oocytes with IC 50 values of 68±6 μM and 4.3±0.3 μM respectively. The three‐dimensional solution structure of hainantoxin‐I belongs to the inhibitor cystine knot structural family determined by two‐dimensional 1 H nuclear magnetic resonance techniques. Structural comparison of hainantoxin‐I with those of other toxins suggests that the combination of the charged residues and a vicinal hydrophobic patch should be responsible for ligand binding. This is the first report of an insect sodium channel blocker from spider venom and it provides useful information for the structure–function relationship studies of insect sodium channels.