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

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 has 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.

Formation Energies of the Lithium Intercalations in MoS_2

First-principles calculations have been performed to study the lithium intercalations in MoS2. The formation energies, changes of volumes, electronic structures and charge densities of the lithium intercalations in MoS2 are presented. Our calculations show that during lithium intercalations in MoS2, the lithium intercalation formation energies per lithium atom are between 2.5 eV to 3.0 eV. The volume expansions of MoS2 due to lithium intercalations are relatively small