Blocking binding of Bacillus thuringiensis Cry1Aa to Bombyx mori cadherin receptor results in only a minor reduction of toxicity.
BACKGROUND
Bacillus thuringiensis Cry1Aa insecticidal protein is the most active known B. thuringiensis toxin against the forest insect pest Lymantria dispar (gypsy moth), unfortunately it is also highly toxic against the non-target insect Bombyx mori (silk worm).


RESULTS
Surface exposed hydrophobic residues over domains II and III were targeted for site-directed mutagenesis. Substitution of a phenylalanine residue (F328) by alanine reduced binding to the Bombyx mori cadherin by 23-fold, reduced biological activity against B. mori by 4-fold, while retaining activity against Lymantria dispar.


CONCLUSIONS
The results identify a novel receptor-binding epitope and demonstrate that virtual elimination of binding to cadherin BR-175 does not completely remove toxicity in the case of B. mori.
You
Taek H
TH
Department of Biochemistry, The Ohio State University, Columbus, OH 43210, USA. you@campbell.edu
Lee
Mi K
MK
Jenkins
Jeremy L
JL
Alzate
Oscar
O
Dean
Donald H
DH
D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D001665:Binding Sites / Q000235:genetics; D012831:Bombyx / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism*; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D018604:Epitope Mapping; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D019476:Insect Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010572:Pest Control, Biological; D011485:Protein Binding / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins; D020349:Surface Plasmon Resonance
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; C095416:Cry toxin receptors; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis