Expression of functional recombinant scorpion beta-neurotoxin Css II in E-coli

The gene for a beta-neurotoxin [Cerrtruroides suffusus suffusus toxin II (C ss II)] from the scorpion C. suffusus suffusus was synthesized by recursive PCR and cloned into the expression vector, pET15b. This recombinant vector was transformed into a thioredoxin mutant host bacterial cell, AD 494(DE3) pLysS, and expression was induced with isopropyl thiogalactoside (IPTG). Al though the level of expression was low, the recombinant toxin was found onl y in the soluble fraction with no evidence for the formation of inclusion b odies as had been observed previously with other scorpion toxins. The recom binant Css II was purified by successive ion-exchange and hydrophobic inter action chromatography. Nuclear magnetic resonance (NMR) and circular dichro ism (CD) spectral measurements indicate that the protein has a native struc ture with no indication of denatured species. The recombinant neurotoxin in hibits the uptake of [H-3]GABA [gamma-aminobutyric acid (GABA)] in neuronal cells as effectively as natural beta-toxins. (C) 2000 Elsevier Science Inc . All rights reserved.