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

Vié V., Van Mau N., Pomarède P., Dance Camille, Schwartz Jean Louis, Laprade Raynald, Frutos Roger, Rang Cécile, Masson Luke, Heitz F., Le Grimellec C.. 2001. Lipid-induced pore formation of the Bacillus thuringiensis Cry1Aa insecticidal toxin. Journal of Membrane Biology, 180 : 195-203.

Résumé : 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 ß-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.

Mots-clés Agrovoc : Bacillus thuringiensis, protéine microbienne, insecticide, pesticide bactérien, membrane cellulaire, structure cellulaire

Classification Agris : H10 - Ravageurs des plantes

Auteurs et affiliations

• Vié V., CNRS (FRA)
• Van Mau N., CRBM (FRA)
• Pomarède P.
• Dance Camille, CIRAD-AMIS-PROTECTION DES CULTURES (FRA)
• Schwartz Jean Louis, Université de Montréal (CAN)
• Laprade Raynald, Université de Montréal (CAN)
• Frutos Roger, CIRAD-AMIS-PROTECTION DES CULTURES (FRA)
• Rang Cécile, CIRAD-AMIS-BIOTROP (FRA)
• Masson Luke, Biotechnology Research Institute (CAN)
• Heitz F., CRBM (FRA)
• Le Grimellec C., CNRS (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/487157/)

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