Expression and purification of the BmK M1 neurotoxin from the scorpion Buthus martensii Karsch

The gene encoding a neurotoxin (BmK M1) from the scorpion Buthus martensii Karsch was expressed in Saccharomyces cerevisiae at a high level with the a lcohol dehydrogenase promoter. SDS-PAGE of the culture confirmed expression and showed secretion into medium from yeast. Recombinant BmK M1 was purifi ed rapidly and efficiently by ion exchange and gel filtration chromatograph y to homogeneity, produced a single band on tricine-SDS-PAGE, and processed the homologous N-terminus. Amino acid analysis and N-terminal sequencing d emonstrated that the recombinant toxin was processed correctly from the alp ha-mating factor leader sequence and was chemically identical to the native form. The expressed recombinant BmK M1 was toxic for mice, which indicated that it was biologically active. Quantitative estimation showed that recom binant BmK M1 had an LD50 similar to that of the native toxin. (C) 1999 Aca demic Press.