title: Binding of Bacillus thuringiensis Cry1Ac toxin to Manduca sexta aminopeptidase-N receptor is not directly related to toxicity.
abstract: Bacillus thuringiensis Cry1Ac delta-endotoxin specifically binds a 115-kDa aminopeptidase-N purified from Manduca sexta midgut. Cry1Ac domain III mutations were constructed around a putative sugar-binding pocket and binding to purified aminopeptidase-N and brush border membrane vesicles (BBMV) was compared to toxicity. Q509A, R511A, Y513A, and 509-511 (QNR-AAA) eliminated aminopeptidase-N binding and reduced binding to BBMV. However, toxicity decreased no more than two-fold, indicating activity is not directly correlated with aminopeptidase-N binding. Analysis of toxin binding to aminopeptidase-N in M. sexta is therefore insufficient for predicting toxicity. Mutants retained binding, however, to another BBMV site, suggesting alternative receptors may compensate in vivo.
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus 43210, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Jenkins
authors.forename: M K
authors.initials: MK
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: Sangadala
authors.forename: M J
authors.initials: MJ
authors.lastname: Adang
authors.forename: D H
authors.initials: DH
authors.lastname: Dean
mesh_terms: D000116:Acetylgalactosamine / Q000378:metabolism; D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D001427:Bacterial Toxins; D001667:Binding, Competitive; D018826:CD13 Antigens / Q000378:metabolism*; D004731:Endotoxins / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D006460:Hemolysin Proteins; D018402:Manduca / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism; D008958:Models, Molecular; D016296:Mutagenesis; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020349:Surface Plasmon Resonance; D013997:Time Factors
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D018826:CD13 Antigens; D000116:Acetylgalactosamine