Cytotoxicity of Bacillus thuringiensis Cry1Ab toxin depends on specific binding of the toxin to the cadherin receptor BT-R1 expressed in insect cells.
The specific role of cadherin receptors in cytotoxicity involving Cry toxins of Bacillus thuringiensis and their interactions with cell membrane has not been defined. To elucidate the involvement of toxin-membrane and toxin-receptor interactions in cytotoxicity, we established a cell-based system utilizing High Five insect cells stably expressing BT-R1, the cadherin receptor for Cry1Ab toxin. Cry1Ab toxin is incorporated into cell membrane in both oligomeric and monomeric form. Monomeric toxin binds specifically to BT-R1 whereas incorporation of oligomeric toxin is nonspecific and lipid dependent. Toxin oligomers in the cell membrane do not produce lytic pores and do not kill insect cells. Rather, cell death correlates with binding of the Cry1Ab toxin monomer to BT-R1, which apparently activates a Mg2+-dependent cellular signaling pathway.
Zhang
X
X
Biological Targets, Inc., Dallas, TX 75235, USA.
Candas
M
M
Griko
N B
NB
Rose-Young
L
L
Bulla
L A
LA
D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000633:toxicity*; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000633:toxicity*; D015820:Cadherins / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004731:Endotoxins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000633:toxicity*; D006460:Hemolysin Proteins; D019476:Insect Proteins / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D018402:Manduca / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D015820:Cadherins; D002614:Chelating Agents; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D011956:Receptors, Cell Surface; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D004533:Egtazic Acid; D004492:Edetic Acid; D008274:Magnesium