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


Por: Rausell C., García-Robles I., Sánchez J., Muñoz-Garay C., Martínez-Ramírez A.C., Real M.D., Bravo A.

Publicada: 1 ene 2004
Resumen:
Binding and pore formation constitute key steps in the mode of action of Bacillus thuringiensis ?-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. © 2003 Elsevier B.V. All rights reserved.

Filiaciones:
Rausell C.:
 Instituto de Biotecnología, Univ. Nac. Auton. de Mexico, Ap. Postal 510-3, Cuernavaca 62250, Morelos, Mexico

García-Robles I.:
 Fac. de Ciencias Biológicas, Universidad de Valencia, Dr. Moliner 50, Burjassot 46100, Valencia, Spain

Sánchez J.:
 Instituto de Biotecnología, Univ. Nac. Auton. de Mexico, Ap. Postal 510-3, Cuernavaca 62250, Morelos, Mexico

Muñoz-Garay C.:
 Instituto de Biotecnología, Univ. Nac. Auton. de Mexico, Ap. Postal 510-3, Cuernavaca 62250, Morelos, Mexico

Martínez-Ramírez A.C.:
 Fac. de Ciencias Biológicas, Universidad de Valencia, Dr. Moliner 50, Burjassot 46100, Valencia, Spain

Real M.D.:
 Fac. de Ciencias Biológicas, Universidad de Valencia, Dr. Moliner 50, Burjassot 46100, Valencia, Spain

Bravo A.:
 Instituto de Biotecnología, Univ. Nac. Auton. de Mexico, Ap. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
ISSN: 00052736
Editorial
Elsevier, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, Países Bajos
Tipo de documento: Article
Volumen: 1660 Número: 1
Páginas: 99-105
WOS Id: 000188707400012
ID de PubMed: 14757225
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