Function and solution structure of hainantoxin-I, a novel insect sodium channel inhibitor from the Chinese bird spider Selenocosmia hainana.
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/beta(1) and the insect sodium channel para/tipE expressed in Xenopus laevis oocytes with IC(50) values of 68+/-6 microM and 4.3+/-0.3 microM 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.
Li
Dongling
D
College of Life Sciences, Peking University, 100871, Beijing, PR China.
Xiao
Yucheng
Y
Hu
Weijun
W
Xie
Jinyun
J
Bosmans
Frank
F
Tytgat
Jan
J
Liang
Songping
S
D000595:Amino Acid Sequence; D000818:Animals; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D004553:Electric Conductivity; D005260:Female; D020128:Inhibitory Concentration 50; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D009865:Oocytes / Q000378:metabolism; D010084:Oxidation-Reduction; D018408:Patch-Clamp Techniques / Q000379:methods; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology; D011487:Protein Conformation; D026941:Sodium Channel Blockers / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology; D013111:Spider Venoms / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D013112:Spiders; D014982:Xenopus laevis
D004220:Disulfides; D009498:Neurotoxins; D010455:Peptides; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D013111:Spider Venoms; D003545:Cysteine