Open AccessIdentification and characterization of Heliothis virescens midgut membrane proteins binding Bacillus thuringiensis δ‐endotoxins
Author(s) -
ODDOU Pascale,
HARTMANN Herbert,
GEISER Martin
Publication year - 1991
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1991.tb16422.x
Subject(s) - bacillus thuringiensis , heliothis virescens , biology , midgut , biochemistry , binding protein , binding site , brush border , toxin , microbiology and biotechnology , membrane , bacteria , botany , vesicle , gene , genetics , larva , noctuidae
To investigate the specificity of Bacillus thuringiensis var. kurstaki strain HD1 insecticidal crystal proteins (ICP), we used membrane preparations obtained from the midgut of Heliothis virescens larvae to perform separate ligand‐blot experiments with the three activated CryIA toxins. The CryIA(a) and the CryIA(b) toxins bind the same 170‐kDa protein, but most likely at two different binding sites. The CryIA(c) toxin binds two proteins of molecular masses 140 kDa and 120 kDa. We also demonstrate that the binding proteins for each of the B. thuringiensis toxins are not part of a covalent complex. Although the 170‐kDa protein is a glycoprotein, endoglycosidase treatment does not prevent the binding of the CryIA(a) or CryIA(b) toxin. This indicates that the sugars are not important for the binding of these toxins. A model for a protein complex binding the B. thuringiensis HD1 ICPs is presented. Our results support the idea that binding proteins on membranes of the gut epithelial cells of H. virescens larvea are important for the specificity of the bacterial toxins.