Improved Insecticidal Toxicity by Fusing Cry1Ac of Bacillus thuringiensis with Av3 of Anemonia viridis
Av3, a neurotoxin of Anemonia viridis, is toxic to crustaceans and cockroaches but inactive in mammals. In the present study, Av3 was expressed in Escherichia coli Origami B (DE3) and purified by reversed-phase liquid chromatography. The purified Av3 was injected into the hemocoel of Helicoverpa armigera, rendering the worm paralyzed. Then, Av3 was expressed alone or fusion expressed with the Cry1Ac in acrystalliferous strain Cry−B of Bacillus thuringiensis. The shape of Cry1Ac was changed by fusion with Av3. The expressed fusion protein, Cry1AcAv3, formed irregular rhombus- or crescent-shaped crystalline inclusions, which is quite different from the shape of original Cry1Ac crystals. The toxicity of Cry1Ac was improved by fused expression. Compared with original Cry1Ac expressed in Cry−B, the oral toxicity of Cry1AcAv3 to H. armigera was elevated about 2.6-fold. No toxicity was detected when Av3 was expressed in Cry−B alone. The present study confirmed that marine toxins could be used in bio-control and implied that fused expression with other insecticidal proteins could be an efficient way for their application.
Keywordscry2Ab Gene Peptide Toxin Overlap Extension Polymerase Chain Reaction Synthetic cry1Ac Isatis Indigotica
The authors would like to thank Dr. Yehu Moran and Prof. Michael Gurevitz of Tel Aviv University for providing the pET32b vector and their good advice. This investigation was supported by the National Natural Science Foundation of China (30970066; 31070006; 30900037), National High Technology Research and Development project (863) of China (2011AA10A203), and the Hunan province science and technology program (2010 FJ 2002).