Role of toxin activation on binding and pore formation activity of the Bacillus thuringiensis Cry3 toxins in membranes of Leptinotarsa decemlineata (Say)

6533b7d4fe1ef96bd1261eaf

RESEARCH PRODUCT

Role of toxin activation on binding and pore formation activity of the Bacillus thuringiensis Cry3 toxins in membranes of Leptinotarsa decemlineata (Say)

Inmaculada García-robles Carlos Muñoz-garay María Dolores Real Alejandra Bravo Jorge Sánchez Carolina Rausell Amparo C. Martínez-ramírez

subject

Proteases Brush border Bacterial Toxins Bacillus thuringiensis Biophysics medicine.disease_cause Binding Competitive Biochemistry Hemolysin Proteins Bacterial Proteins Bacillus thuringiensis Endopeptidases medicine Animals Protoxin activation Binding site Protein Precursors Chymotrypsin Binding Sites biology Bacillus thuringiensis Toxins Microvilli Toxin Colorado potato beetle Cell Membrane fungi Cell Biology biology.organism_classification Trypsin Coleoptera Endotoxins Biochemistry Mode of action biology.protein medicine.drug

description

AbstractBinding and pore formation constitute key steps in the mode of action of Bacillus thuringiensis δ-endotoxins.In this work, we present a comparative analysis of toxin-binding capacities of proteolytically processed Cry3A, Cry3B and Cry3C toxins to brush border membranes (BBMV) of the Colorado potato beetle Leptinotarsa decemlineata (CPB), a major potato coleopteran-insect pest. Competition experiments showed that the three Cry3 proteolytically activated toxins share a common binding site. Also heterologous competition experiments showed that Cry3Aa and Cry3Ca toxins have an extra binding site that is not shared with Cry3Ba toxin. The pore formation activity of the three different Cry3 toxins is analysed. High pore-formation activities were observed in Cry3 toxins obtained by proteolytical activation with CPB BBMV in contrast to toxins activated with either trypsin or chymotrypsin proteases. The pore-formation activity correlated with the formation of soluble oligomeric structures. Our data support that, similarly to the Cry1A toxins, the Cry3 oligomer is formed after receptor binding and before membrane insertion, forming a pre-pore structure that is insertion-competent.

year	journal	country	edition	language
2004-02-06	Biochimica et Biophysica Acta (BBA) - Biomembranes

10.1016/j.bbamem.2003.11.004 http://dx.doi.org/10.1016/j.bbamem.2003.11.004