Synthesis and Characterization of Cry2Ab-AVM Bioconjugate: Enhanced Affinity to Binding Proteins and Insecticidal Activity.

insecticidal proteins (Bt toxins) have been widely used in crops for agricultural pest management and to reduce the use of chemical insecticides. Here, we have engineered Bt toxin Cry2Ab30 and bioconjugated it with 4"-O-succinyl avermectin (AVM) to synthesize Cry2Ab-AVM bioconjugate. It was found that Cry2Ab-AVM showed higher insecticidal activity against , up to 154.

Exposure of helices α4 and α5 is required for insecticidal activity of Cry2Ab by promoting assembly of a prepore oligomeric structure.

Cry2Ab, a pore-forming toxin derived from Bacillus thuringiensis, is widely used as a bio-insecticide to control lepidopteran pests around the world. A previous study revealed that proteolytic activation of Cry2Ab by Plutella xylostella midgut juice was essential for its insecticidal activity against P. xylostella, although the exact molecular mechanism remained unknown.

Proteolytic activation of Bacillus thuringiensis Vip3Aa protein by Spodoptera exigua midgut protease.

Proteolysis of Vip3Aa by insect midgut proteases is essential for their toxicity against target insects. In the present study, proteolysis of Vip3Aa was evaluated by Spodoptera exigua midgut proteases (MJ). Trypsin was verified involved in the activation of Vip3Aa and three potential cleavage sites (Lys, Lys and Lys) were identified.