Cry11Aa toxin from Bacillus thuringiensis binds its receptor in Aedes aegypti mosquito larvae through loop α-8 of domain II

Fernández, Luisa E.; Pérez, Claudia; Segovia, Lorenzo; Rodríguez, Mario H.; Gill, Sarjeet S.; Bravo, Alejandra; Soberón, Mario

doi:10.1016/j.febslet.2005.05.032

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Volume 579, Issue 17 , Pages 3508-3514, 4 July 2005

Cry11Aa toxin from Bacillus thuringiensis binds its receptor in Aedes aegypti mosquito larvae through loop α-8 of domain II

Edited by Maurice Montal

Luisa E. Fernández
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
Claudia Pérez
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
Lorenzo Segovia
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
Mario H. Rodríguez
- Instituto Nacional de Salud Pública, Av. Universidad 655, Cuernavaca 62508, Morelos, Mexico
Sarjeet S. Gill
- University of California, Riverside, CA 92506, USA
Alejandra Bravo
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
Mario Soberón
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
- Corresponding author. Fax: +52 777 3172388.

Received 13 April 2005; received in revised form 16 May 2005; accepted 16 May 2005. published online 03 June 2005.

Abstract

Bacillus thuringiensis subs israelensis produces Cry toxins active against mosquitoes. Receptor binding is a key determinant for specificity of Cry toxins composed of three domains. We found that exposed loop α-8 of Cry11Aa toxin, located in domain II, is an important epitope involved in receptor interaction. Synthetic peptides corresponding to exposed regions in domain II (loop α-8, β-4 and loop 3) competed binding of Cry11Aa to membrane vesicles from Aedes aegypti midgut microvilli. The role of loop α-8 of Cry11A in receptor interaction was demonstrated by phage display and site-directed mutagenesis. We isolated a peptide-displaying phage (P5.tox), that recognizes loop α-8 in Cry11Aa, interferes interaction with the midgut receptor and attenuates toxicity in bioassay. Loop α-8 mutants affected in toxicity and receptor binding were characterized.

Abbreviations: BBMV, brush border membrane vesicles, PFU, plaque-forming units, ELISA, enzyme-linked immunosorbent assay

Keywords: δ-Endotoxin, Receptor binding, Phage display, Epitope mapping