BotIT6: a potent depressant insect toxin from Buthus occitanus tunetanus venom.
A new depressant insect toxin Buthus occitanus tunetanus insect-toxin 6 (BotIT6) was purified by high-performance liquid chromatography from Buthus occitanus tunetanus (Bot) venom. BotIT6 is very active against Blatella germanica (LD50=10ng/100mg body mass) thus being one of the most potent anti-insect toxin so far characterised. When compared to other insect toxin sequences, BotIT6 present high similarities with depressant insect toxins with an additional arginine residue at the C-terminus and a methionine at position 27. The calculated net charge of BotIT6 is positive (+3) whereas it is negative for classical depressant toxins: this might be associated with its high toxicity. Voltage current clump studies show that BotIT6 is not a very potent depressant insect toxin despite its high toxicity in vivo. BotIT6 is able to fully inhibit the specific binding of 125I AaHIT and 125I-BotIT2 on Periplaneta americana synaptosomal membrane vesicles with high affinities. Despite its higher toxicity BotIT6 is a weaker competitor with 125I AaHIT and 125I BotIT2 as compared to the other beta toxins.Altogether, these results may suggest that BotIT6 probably defines a novel sub-group of depressant anti-insect toxins for which the receptor site can be overlapping, but not identical to that for classical depressant insect toxins.
Mejri
Thouraya
T
Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, BP 74-1002, Tunis, Tunisia. mijthouraya@excite.com
Borchani
Lamia
L
Srairi-Abid
Najet
N
Benkhalifa
Rym
R
Cestele
Sandrine
S
Regaya
Imed
I
Karoui
Habib
H
Pelhate
Marcel
M
Rochat
Hervé
H
El Ayeb
Mohamed
M
D000200:Action Potentials / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D002492:Central Nervous System Depressants / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004594:Electrophysiology; D004797:Enzyme-Linked Immunosorbent Assay; D007276:Injections, Intraventricular; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010526:Periplaneta / Q000187:drug effects; D012604:Scorpion Venoms / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D012605:Scorpions / Q000502:physiology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
C472492:BotIT6 protein, Buthus occitanus tunetanus; D002492:Central Nervous System Depressants; D012604:Scorpion Venoms