TY  - JOUR
AB  - The present study describes the isolation and pharmacological characterisation of the neurotoxin ?-missulenatoxin-Mb1a (?-MSTX-Mb1a) from the venom of the male Australian eastern mouse spider, Missulena bradleyi. This toxin was isolated using reverse-phase high-performance liquid chromatography and was subsequently shown to cause an increase in resting tension, muscle fasciculation and a decrease in indirect twitch tension in a chick biventer cervicis nerve-muscle bioassay. Interestingly, these effects were neutralised by antivenom raised against the venom of the Sydney funnel-web spider Atrax robustus. Subsequent whole-cell patch-clamp electrophysiology on rat dorsal root ganglion neurones revealed that ?-MSTX-Mb1a caused a reduction in peak tetrodotoxin (TTX)-sensitive sodium current, a slowing of sodium current inactivation and a hyperpolarising shift in the voltage at half-maximal activation. In addition, ?-MSTX-Mb1a failed to affect TTX-resistant sodium currents. Subsequent Edman degradation revealed a 42-residue peptide with unusual N- and C-terminal cysteines and a cysteine triplet (Cys14-16). This toxin was highly homologous to a family of ?-atracotoxins (?-ACTX) from Australian funnel-web spiders including conservation of all eight cysteine residues. In addition to actions on sodium channel gating and kinetics to ?-ACTX, ?-MSTX-Mb1a caused significant insect toxicity at doses up to 2000 pmol/g. ?-MSTX-Mb1a therefore provides evidence of a highly conserved spider ?-toxin from a phylogenetically distinct spider family that has not undergone significant modification. © 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.
AU  - Gunning, SJ
AU  - Chong, Y
AU  - Khalife, AA
AU  - Hains, PG
AU  - Broady, KW
AU  - Nicholson, GM
DA  - 2003/11/06
DO  - 10.1016/S0014-5793(03)01175-X
EP  - 218
JO  - FEBS Letters
PY  - 2003/11/06
SP  - 211
TI  - Isolation of ?-missulenatoxin-Mb1a, the major vertebrate-active spider ?-toxin from the venom of Missulena bradleyi (Actinopodidae)
VL  - 554
Y1  - 2003/11/06
Y2  - 2026/07/27
ER  -