Functional complementation of nontoxic mutant binary toxins of Bacillus sphaericus 1593M generated by site-directed mutagenesis

Site-directed mutagenesis was applied to examine the mode of action of the binary toxin formed by the combination of two mosquito larvicidal proteins of 51 and 42kDa. On its own, each of these peptides is nontoxic. When synthesized by Bacillus sphaericus 1593M during sporulation, the peptides of 51 and 42 kDa show toxicity. The impact of the substitution of alanine residues for other amino acids found at the N- and C-terminal regions of the binary the binary toxin on biological activity was investigated.