Computational tridimensional protein modeling of Cry1Ab19 toxin from Bacillus thuringiensis BtX-2

We report the computational structural simulation of the Cry1Ab19 toxin molecule from B. thuringiensis BtX-2 based on the structure of Cry1Aa1 deduced by x-ray diffraction. Validation results showed that 93.5% of modeled residues are folded in a favorable orientation with a total energy Z-score of -8.32, and the constructed model has an RMSD of only 1.13. The major differences in the presented model are longer loop lengths and shortened sheet components. The overall result supports the hierarchical three-domain structural hypothesis of Cry toxins and will help in better understanding the structural variation within the Cry toxin family along with facilitating the design of domain-swapping experiments aimed at improving the toxicity of native toxins.