Binding of Bacillus sphaericus binary toxin to a specific receptor on midgut brush-border membranes from mosquito larvae.
The presence of specific receptors for Bacillus sphaericus binary toxin on brush-border membrane fractions (BBMF) from Culex pipiens larvae midgut cells was demonstrated by an in vitro binding assay. Both activated and radiolabelled polypeptides from the 51-kDa and 42-kDa binary toxin of B. sphaericus 1593 specifically bound to BBMF. Direct binding and homologous competition experiments indicated a single class of B. sphaericus toxin receptors, with a dissociation constant (Kd) of approximately 20 nM and a maximum binding capacity (Bmax) of approximately 7 pmol/mg BBMF protein. The sugars GalNAc, GlcNAc and N-acetyl neuraminic acid had no detectable inhibitory effect on toxin binding to C. pipiens BBMF. Binding experiments with the non-susceptible mosquito species Aedes aegypti failed to detect significant binding of B. sphaericus binary toxin to A. aegypti BBMF.
Nielsen-Leroux
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Bactéries Entomopathogènes, Institut Pasteur, Paris, France.
Charles
J F
JF
D000116:Acetylgalactosamine / Q000494:pharmacology; D000117:Acetylglucosamine / Q000494:pharmacology; D000330:Aedes / Q000378:metabolism; D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D001667:Binding, Competitive; D003465:Culex / Q000378:metabolism*; D007814:Larva / Q000378:metabolism / Q000648:ultrastructure; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism; D019158:N-Acetylneuraminic Acid; D011955:Receptors, Drug / Q000378:metabolism*; D012794:Sialic Acids / Q000494:pharmacology
D001427:Bacterial Toxins; D011955:Receptors, Drug; D012794:Sialic Acids; C046134:binB protein, Bacillus sphaericus; D019158:N-Acetylneuraminic Acid; D000116:Acetylgalactosamine; D000117:Acetylglucosamine