Sequence and electrophysiological characterization of two insect-selective excitatory toxins from the venom of the Chinese scorpion Buthus martensi.
The two insecticidal peptides Bm32-VI and Bm33-I, isolated from the venom of the Chinese scorpion Buthus martensi induce paralytical symptoms typical of insect contractive toxins. They show, respectively, 74% and 77% homology with AaIT from Androctonus australis, comparable insecticidal activity and no vertebrate toxicity. Under voltage-clamp conditions, both toxins induced (1) an increased fast Na(+) current, (2) a shift in voltage dependence of Na(+) current activation, (3) the occurrence of a delayed current, and (4) a slow development of a holding current. Increased Na(+) conductance at negative potential values is responsible for axonal hyperexcitability and the contractive paralysis of insect prey.
Escoubas
P
P
Suntory Institute for Bioorganic Research, Wakayamadai, Osaka, Japan. pescoubas@compuserve.com
Stankiewicz
M
M
Takaoka
T
T
Pelhate
M
M
Romi-Lebrun
R
R
Wu
F Q
FQ
Nakajima
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D003058:Cockroaches; D004594:Electrophysiology; D007276:Injections, Intraventricular; D007306:Insecticides / Q000737:chemistry* / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D012604:Scorpion Venoms / Q000737:chemistry* / Q000494:pharmacology; D012605:Scorpions / Q000737:chemistry*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D018675:Toxicity Tests
D007306:Insecticides; D012604:Scorpion Venoms