Tandem Expression and Functional Analysis of Common Structure Short Peptides of Bacillus thuringiensis Cry Toxins
Bacillus thuringiensis(Bt)Cry toxins are a class of microbial proteins with insecticidal activities.Previously,based on the amino acid sequence and structural information of the Bt Cry toxin family,three short peptides presenting the common structure of Cry toxins were designed and obtained.These peptides were spliced to be a polypeptide with immunogenicity(Bt Cry-GXJG-11),which was potentially to be used to design novel insecticidal mimics of Bt Cry toxins,and to produce broad specificity antibodies against Bt Cry toxins as the immunogen.Molecular modeling showed that Bt Cry-GXJG-11 was potentially interacting with HaCad-TBR,which was a recombinant expressed receptor of Cry toxins in Helicoverpa armigera and the contacting amino acids(244TYR)in the complex were also predicted.After prokaryotic expression,the purified Bt Cry-GXJG-11 was obtained at a concentration of 0.5 mg/mL,and its affinity constant(KD)with HaCad-TBR was measured to be 2.151×10-7 mol/L.The bioassay showed that Bt Cry-GXJG-11 had weak insecticidal activity against H.armigera,with the mortality of 27.5%.In addition,the antiserum of mice immunized with Bt Cry-GXJG-11 could simultaneously recognize six Cry toxins(Cry1Ab,Cry1Ac,Cry1Ah,Cry1B,Cry1C,Cry1F).
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