Structure Elucidation, Biological and Molecular Docking Studies of the δ‑Endotoxin Cry1Ca17 from Bacillus thuringiensis Strain BUPM14.

The discovery of novel δ-endotoxins from Bacillus thuringiensis strains is a continuous action that falls within the framework of pest control and the prevention of pest resistance. Using conventional techniques and 16S rDNA analysis, the BUPM14 isolate was interestingly assigned as a B. thuringiensis subsp. kurstaki strain that acquired a cry1C gene. It exhibited significant insecticidal toxicity to Lepidopteran insects. The cry1C gene was cloned and sequenced. It has 3573 bp nucleotides and encodes a protein with a calculated molecular mass of 134.673 kDa. This δ-endotoxin showed high homology (99%) with Cry1C δ-endotoxins with five conserved domains, typical features of the Lepidoptera-active crystal proteins. Therefore, it was named Cry1Ca17 according to the Bt toxin nomenclature system. Molecular docking studies were carried out to display the key amino acid residues involved in the toxin-receptor interaction at two levels, viz. the receptor toxin-binding site (toxin-binding site) and the catalytic site (toxin-catalytic site). These were compared to those involved in the toxin-receptor complexes known to date.