来自苏云金芽孢杆菌的Cry11Aa毒素通过结构域II的α-8环与埃及伊蚊幼虫中的受体结合。

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

作者信息

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

机构信息

Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico.

出版信息

FEBS Lett. 2005 Jul 4;579(17):3508-14. doi: 10.1016/j.febslet.2005.05.032.

DOI:10.1016/j.febslet.2005.05.032

PMID:15963509

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 alpha-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 alpha-8, beta-4 and loop 3) competed binding of Cry11Aa to membrane vesicles from Aedes aegypti midgut microvilli. The role of loop alpha-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 alpha-8 in Cry11Aa, interferes interaction with the midgut receptor and attenuates toxicity in bioassay. Loop alpha-8 mutants affected in toxicity and receptor binding were characterized.

摘要

苏云金芽孢杆菌以色列亚种产生对蚊子有活性的Cry毒素。受体结合是由三个结构域组成的Cry毒素特异性的关键决定因素。我们发现位于结构域II的Cry11Aa毒素的暴露环α-8是参与受体相互作用的重要表位。与结构域II中暴露区域（环α-8、β-4和环3）相对应的合成肽竞争Cry11Aa与埃及伊蚊中肠微绒毛膜囊泡的结合。通过噬菌体展示和定点诱变证明了Cry11A的环α-8在受体相互作用中的作用。我们分离出一种展示肽的噬菌体（P5.tox），它识别Cry11Aa中的环α-8，干扰与中肠受体的相互作用并在生物测定中减弱毒性。对在毒性和受体结合方面受影响的环α-8突变体进行了表征。