Expression of an insect excitatory toxin, BmK IT, from the scorpion, Buthus martensii Karsch, and its biological activity.

An insect excitatory toxin from Buthus martensii Karsch (BmK IT) was cloned into the expression vector, pTWIN1, and expressed into Escherichia coli BL21 (DE3) host cells. The soluble fusion expression of CBD-intein-BmK IT was obtained. The recombinant BmK IT was purified by two anion-exchange chromatography columns and one gel chromatography column. Bioassays were carried out to verify the toxicity of this recombinant toxin. At the end of a 96 h experimental period, 83% of cotton bollworm larvae were killed with an LT(50) value of 58-62 h. Furthermore, the average weight of larvae fed on BmK IT-containing media was approx 4% of that of the control groups. The results indicate that the expressed and purified recombinant BmK IT has biological activity.