Biotechnology Letters, Vol.35, No.11, 1889-1894, 2013
Identification of a second cytotoxic protein produced by Bacillus thuringiensis A1470
Bacillus thuringiensis A1470 produces multiple proteins with similar molecular masses (similar to 30 kDa) with cytotoxicity against human cell lines. One that was previously identified, parasporin-4, is a beta-pore-forming toxin. The N-terminal sequence of a second cytotoxic protein was identical to a partial sequence of parasporin-2 produced by B. thuringiensis A1547. PCR was performed on total plasmid DNA from A1470 by using primers for parasporin-2 to amplify a gene which was then cloned. The cloned gene differed from A1547 parasporin-2 by 8 bp and the predicted protein differed by four amino acids. The gene was expressed in Escherichia coli, and the cytotoxic activities of the recombinant protein against four human cell lines (MOLT-4, Jurkat, HeLa, and HepG2) were similar to those of A1547 parasporin-2. We then confirmed that the A1470 strain simultaneously produces parasporin-2 and parasporin-4.
Keywords:Bacillus thuringiensis;Cytotoxicity;Human cancer cell;Non-insecticidal;Parasporal inclusion protein