The C-terminal domain of the toxic fragment of a Bacillus thuringiensis crystal protein determines receptor binding.
The insecticidal crystal proteins of Bacillus thuringiensis show a high degree of specificity. In vitro binding studies with several crystal proteins demonstrated a correlation between toxicity and binding to receptors of larval midgut epithelial cells. In order to study the domain-function relationships of the toxic fragment, hybrid crystal proteins based on CryIA(b) and CryIC were constructed. Two out of 11 hybrid proteins constructed exhibited insecticidal activity. Both dispalyed an insecticidal spectrum similar to that of the parental crystal protein from which the C-terminal part of the toxic fragment originated. In addition, in vitro binding studies directly demonstrated the involvement of the C-terminal part of the toxic fragment in receptor binding. These results demonstrate that the C-terminal part of the toxic fragment determines specific receptor binding, which in turn determines, to a large extent, the insect specificity.
Honée
G
G
Centre for Plant Breeding and Reproduction Research, Wageningen, The Netherlands.
Convents
D
D
Van Rie
J
J
Jansens
S
S
Peferoen
M
M
Visser
B
B
D000595:Amino Acid Sequence; D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D001427:Bacterial Toxins; D001483:Base Sequence; D004731:Endotoxins; D005813:Genes, Synthetic; D006460:Hemolysin Proteins; D007814:Larva; D008969:Molecular Sequence Data; D009036:Moths / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding; D015202:Protein Engineering; D011956:Receptors, Cell Surface / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000633:toxicity
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis