title: Cry1Aa binding to the cadherin receptor does not require conserved amino acid sequences in the domain II loops.
abstract: Characterizing the binding mechanism of Bt (Bacillus thuringiensis) Cry toxin to the cadherin receptor is indispensable to understanding the specific insecticidal activity of this toxin. To this end, we constructed 30 loop mutants by randomly inserting four serial amino acids covering all four receptor binding loops (loops α8, 1, 2 and 3) and analysed their binding affinities for Bombyx mori cadherin receptors via Biacore. High binding affinities were confirmed for all 30 mutants containing loop sequences that differed from those of wild-type. Insecticidal activities were confirmed in at least one mutant from loops 1, 2 and 3, suggesting that there is no critical amino acid sequence for the binding of the four loops to BtR175. When two mutations at different loops were integrated into one molecule, no reduction in binding affinity was observed compared with wild-type sequences. Based on these results, we discussed the binding mechanism of Cry toxin to cadherin protein.
authors.affiliation: Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Fujii
authors.forename: Shiho
authors.initials: S
authors.lastname: Tanaka
authors.forename: Manami
authors.initials: M
authors.lastname: Otsuki
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hoshino
authors.forename: Chinatsu
authors.initials: C
authors.lastname: Morimoto
authors.forename: Takuya
authors.initials: T
authors.lastname: Kotani
authors.forename: Yuko
authors.initials: Y
authors.lastname: Harashima
authors.forename: Haruka
authors.initials: H
authors.lastname: Endo
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Yoshizawa
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Sato
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism*; D017123:Bacteriophage T7 / Q000235:genetics / Q000378:metabolism; D012831:Bombyx / Q000187:drug effects / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism*; D017124:Conserved Sequence; D004731:Endotoxins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors / Q000378:metabolism; D006460:Hemolysin Proteins / Q000378:metabolism*; D019476:Insect Proteins / Q000378:metabolism*; D007306:Insecticides / Q000378:metabolism / Q000494:pharmacology; D007814:Larva / Q000378:metabolism; D009154:Mutation; D010572:Pest Control, Biological / Q000379:methods; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; C095416:Cry toxin receptors; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D007306:Insecticides; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis