Characterization of the Novel Insecticidal Crystal Protein Cyt3Aa1 from &i&Bacillus thuringiensis&/i& TD516

摘要

Bacillus thuringiensis (Bt) produces two families of insecticidal crystal proteins, i.e. , crystalline (Cry) and cytolytic (Cyt) toxins. Cyt3Aa1, the newest Cyt family member, is produced by Bt TD516. Bioassay results have shown that Cyt3Aa1 has weak hemolytic activity against human red blood cells and is not toxic to A. aegypti larvae, but causing a teratogenic effect. The three-dimensional structure of Cyt3Aa1 ha s a typical cytolysin fold containing a β -sheet held by two surrounding α -helical layers, resembling the previously reported Cyt1Aa and Cyt2Aa structures, which indicated that Cyt3Aa1 might be a membrane-perforation toxin and could induce synergism with Cry protein. This study provides a new source of insecticidal crystal proteins, and presents a foundation for understanding the biological characterization of it, which will aid in the development of strategies to cope with the potential problem of insect resistance.