133 kDa Crystal Protein (Cry1Ac)

Pesticidal crystal protein, Cry1Ac, promotes colloidosmotic lysis by binding to the midgut epithelial cells of many lepidopteran larvae. This protein is produced during sporulation and is accumulated both as an inclusion and as part of the spore coat.

When insects ingest toxin crystals, the alkaline pH of their digestive tract denatures the insoluble crystals, making them soluble and thus amenable to being cut with proteases found in the insect gut, which liberate the cry toxin from the crystal. 

Cry1Ac insecticidal crystal proteins produced by Bacillus thuringiensis (Bt) have become an important natural biological agent for the control of lepidopteran insects. In this study, a cry1Ac toxin gene from Bacillus thuringiensis 4.0718 was modified by using error-prone PCR, staggered extension process (StEP) shuffling combined with Red/ET homologous recombination to investigate the insecticidal activity of delta-endotoxin Cry1Ac.