The mode of action of Bacillus thuringiensis crystal proteins

Irreversible Binding Kinetics of Bacillus thuringiensis CryIA δ-Endotoxins to Gypsy Moth Brush Border Membrane Vesicles Is Directly Correlated to Toxicity

“…The toxins then bind to specific binding proteins in the microvilli of columnar cells and insert into the membrane of the microvilli. Pore formation by the toxins in the membrane causes the leakage of ions and probably other contents of the cell and finally lyses the cell (1,2).…”

“…An in vitro system with brush border membrane vesicles (BBMV) 1 established by Wolfersberger et al (3) has made it possible to study binding at the molecular level. Hofmann et al (4) were the first to identify specific binding sites of toxins in the BBMV of susceptible insects by binding assays.…”

Ion-Channel Diversity

“…and water into the midgut epithelium cells. Ultimately, the insect will die from complications produced by extensive osmotic swelling and midgut epithelium cell lysis (39,41). The Bt 5-endotoxin proteins are toxic to select larval Lepidoptera, Diptera and Coleoptera.…”

“…Ultimately, the leakage of cations and water will destroy the basal-side to apicalside transepithelial potential difference which in turn disrupts pH regulation and nutrient uptake. These physiological events culminate in the cytolysis of midgut epithelium cells and cause the death of the insect (41).…”

Bacillus sphaericus and Bacillus thuringiensis to Insect Control: Process Development of Small Scale Production to Pilot-Plant-Fermenters

“…The crystal structure is comprised of three distinct domains: Domain I (a 7 α-helical bundle) is equipped for pore formation in insect epithelial membrane; Domain II (a triple -sheet structure) may be responsible for receptor recognition; Domain III (a -sandwich region) may protect the toxin from further degradation during proteolytic processing (Honée and Visser, 1993;Vontersch et al, 1994). Depending on the variety of species, the -endotoxins are composed of different structures and molecular weights ranging between 27 and 160 kDa.…”