title: Reduction of Bacillus thuringiensis Cry1Ac toxicity against Helicoverpa armigera by a soluble toxin-binding cadherin fragment.
abstract: A cadherin-like protein has been identified as a putative receptor for Bacillus thuringiensis (Bt) Cry1Ac toxin in Helicoverpa armigera and plays a key role in Bt insecticidal action. In this study, we produced a fragment from this H. armigera Cry1Ac toxin-binding cadherin that included the predicted toxin-binding region. Binding of Cry1Ac toxin to this cadherin fragment facilitated the formation of a 250-kDa toxin oligomer. The cadherin fragment was evaluated for its effect on Cry1Ac toxin-binding and toxicity by ligand blotting, binding assays, and bioassays. The results of ligand blotting and binding assays revealed that the binding of Cry1Ac to H. armigera midgut epithelial cells was reduced under denaturing or native conditions in vitro. Bioassay results indicated that toxicities from Cry1Ac protoxin or activated toxin were reduced in vivo by the H. armigera cadherin fragment. The addition of the cadherin fragment had no effect on Cry2Ab toxicity.
authors.affiliation: State Key Laboratory of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Chenxi
authors.initials: C
authors.lastname: Liu
authors.forename: Kongming
authors.initials: K
authors.lastname: Wu
authors.forename: Yidong
authors.initials: Y
authors.lastname: Wu
authors.forename: Yulin
authors.initials: Y
authors.lastname: Gao
authors.forename: Changming
authors.initials: C
authors.lastname: Ning
authors.forename: Brenda
authors.initials: B
authors.lastname: Oppert
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism / Q000633:toxicity*; D015820:Cadherins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004731:Endotoxins / Q000378:metabolism / Q000633:toxicity*; D006460:Hemolysin Proteins / Q000378:metabolism / Q000633:toxicity*; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007306:Insecticides / Q000378:metabolism / Q000633:toxicity*; D009036:Moths / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D011485:Protein Binding; D012995:Solubility
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis