Lipid-induced pore formation of the Bacillus thuringiensis Cry1Aa insecticidal toxin

After activation, Bacillus thuringiensis (Bt) insecticidal toxin forms pores in larval midgut epithelial cell membranes, leading to host death. Although the crystal structure of the soluble form of Cry1Aa has been determined, the conformation of the pores and the mechanism of toxin interaction with...

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Bibliographic Details
Published inThe Journal of membrane biology Vol. 180; no. 3; pp. 195 - 203
Main Authors Vié, V, Van Mau, N, Pomarède, P, Dance, C, Schwartz, J L, Laprade, R, Frutos, R, Rang, C, Masson, L, Heitz, F, Le Grimellec, C
Format Journal Article
LanguageEnglish
Published United States 01.04.2001
Subjects
Bacillus thuringiensis
Bacterial Proteins - metabolism
Bacterial Toxins - metabolism
Endotoxins - metabolism
Hemolysin Proteins
Insecticides - metabolism
Lipid Bilayers - metabolism
Lipid Metabolism
Spectroscopy, Fourier Transform Infrared - methods
Water - metabolism
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Summary:After activation, Bacillus thuringiensis (Bt) insecticidal toxin forms pores in larval midgut epithelial cell membranes, leading to host death. Although the crystal structure of the soluble form of Cry1Aa has been determined, the conformation of the pores and the mechanism of toxin interaction with and insertion into membranes are still not clear. Here we show that Cry1Aa spontaneously inserts into lipid mono- and bilayer membranes of appropriate compositions. Fourier Transform InfraRed spectroscopy (FTIR) indicates that insertion is accompanied by conformational changes characterized mainly by an unfolding of the beta-sheet domains. Moreover, Atomic Force Microscopy (AFM) imaging strongly suggests that the pores are composed of four subunits surrounding a 1.5 nm diameter central depression.
ISSN:0022-2631
1432-1424
DOI:10.1007/s002320010070