title: Increased toxicity of modified mosquitocidal binary toxins of Bacillus sphaericus expressed in Escherichia coli.
abstract: The binary mosquitocidal genes of 51-kDa and 42-kDa proteins isolated from Bacillus sphaericus 1593 have been expressed at moderate levels in Escherichia coli employing the pQE expression system. The expressed proteins are readily visible in Coomassie blue-stained protein gels. The recombinant E. coli cells expressing toxic proteins were toxic towards Culex larvae. During the assembly of crystals in B. sphaericus, the 42-kDa toxin is first cleaved at the N-terminal end by a specific B. sphaericus protease. To express the toxins in E. coli the B. sphaericus specific protease-recognition site was deleted at the N-terminal end of the 42-kDa toxin, thereby mimicking the structure of the toxin as present in the crystal. This modification resulted in a twofold increase in the toxicity of the E. coli cells expressing the modified 42-kDa toxin as a constituent of the binary toxin. Our results demonstrate the utility of this modification for heterologous expression of the binary toxin genes from B. sphaericus.
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
authors.forename: S
authors.initials: S
authors.lastname: Ahmad
authors.forename: A
authors.initials: A
authors.lastname: Selvapandiyan
authors.forename: R K
authors.initials: RK
authors.lastname: Bhatnagar
mesh_terms: D000818:Animals; D001407:Bacillus / Q000235:genetics*; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics / Q000633:toxicity*; D003465:Culex; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics*; D015870:Gene Expression; D007814:Larva; D010957:Plasmids; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000633:toxicity
chemical_list: D001427:Bacterial Toxins; D011994:Recombinant Proteins; C046134:binB protein, Bacillus sphaericus