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A comparison and analysis of the toxicity and receptor binding properties of Bacillus thuringiensis CryIC ∂‐endotoxin on Spodoptera littoralis and Bombyx mori
Author(s) -
Sanchis Vincent,
Chaufaux Josette,
Pauron David
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01057-9
Subject(s) - bacillus thuringiensis , spodoptera littoralis , spodoptera , bombyx mori , microbiology and biotechnology , spodoptera litura , toxicity , biology , chemistry , botany , noctuidae , biochemistry , larva , bacteria , genetics , recombinant dna , organic chemistry , gene
The binding of l ‐[ 35 S]methionine in vivo labelled CryIC toxin to its receptor in brush border membrane vesicle (BBMV's) prepared from Spodoptera littoralis and Bombyx mori was studied. Both insect species were highly susceptible to the CryIC toxin in bioassays, B. mori being 7‐fold more sensitive to CryIC than S. littoralis (LC50's of 10 ng/cm 2 and 70 ng/cm 2 , respectively). Competition and direct binding experiments revealed saturable high‐affinity binding sites on BBMV's from both insects which had similar binding characteristics for the CryIC toxin ( K d = 10 nM, B max = 8 to 9 pmol/mg BBMV's and IC 50 = 37 nM for both insect species). Thus a specific receptor for the CryIC toxin is present in both insect species and the 7‐fold greater potency of CryIC towards B. mori is not due to qualitative or quantitative differences in binding affinity or receptor site concentration. Dissociation experiments also indicated that the binding of [ 35 S]CryIC to B. mori BBMV's is partially reversible.