Expression of a Fusion Protein with Cry1Ac Protein and a Scorpion Insect Toxin in Acrystalliferous Bacillus thuringiensis Strain

Expression of a fusion protein between B. thuringiensis crystal protein, Cry1Ac1 and a scorpion insect toxin (AaIT, Androctonus australis Hector insect toxin) in acrystalliferous B. thuringiensis strain (Cry B strain) was examined. The cry1Ac1 gene was cloned in B. thuringiensis-E. coli shuttle vector, pHT3101, under the control of the native cry1Ac1 gene promoter (pProAc) and a gene encoding AaIT was inserted in XhoI site in the middle of the cry1Ac1 gene (pProAc-ScoR). B. thuringiensis Cry-B strain carrying pProAc-ScoR (ProAc-ScoR/CB) produced an inclusion body of irregular shape and the expressed fusion protein is approximately 65 kDa in size. Sporulated cells and spore-crystal mixtures of ProAc-ScoR/CB had insecticidal activity against Plutella xylostella larvae, showing LT50 of ProAc-ScoR/CB (22.59 hrs) lower than that of ProAc/CB (30.06 hrs) at 1×10(7) CFU/cm2. These results suggest that the fusion protein including a B. thuringiensis crystal protein and an AaIT may be functionally expressed in B. thupingiensis. Moreover, we verified the additive toxicity of AaIT, which is a new feasible candidate for insect control.