FUNCTIONAL DOMAINS OF BACILLUS THURINGIENSIS ENDOTOXIN

苏云金芽孢杆菌是一种广泛应用的强效微生物杀虫剂。 用来控制农业害虫，以及蚊子和苍蝇 是人类疾病的传播者。活性杀虫成分为 Delta-内毒素，其特异性各不相同，但被认为具有 类似的行动模式。它们从原毒素的形式被加工成 昆虫中肠中的蛋白酶所产生的活性毒素。活性毒素结合 通过形成一个孔或离子通道而引起细胞溶解。 这项建议的总体目标是详细了解 其体内蛋白质毒素的生化作用机制 膜与受体蛋白的相互作用及其功能 插入和离子通道活性。 本提案的具体目标是确定氨基酸 参与杀虫剂的受体结合和离子通道功能 毒素。分子、遗传、生化和电生理 定点突变、化学修饰、 采用电压钳制和膜片钳技术来检测毒素的作用。 从这个项目中获得的知识将提供对 杀虫晶体蛋白的作用方式以设计更多 针对害虫的特效和更有效的毒素。远距离目标 就是利用这些信息来设计更好的生物杀虫剂来对抗昆虫 人类疾病的传播者。

Bacillus thuringiensis is a potent microbial insecticide that is widely used to control agricultural pests, and mosquitoes and blackflies which are vectors of human diseases. The active insecticidal components are the delta-endotoxins which vary in specificity, but are believed to have similar modes of action. They are processed from the protoxin form to active toxins by proteases in the insect midguts. The active toxin binds to receptors and causes cytolysis by forming a pore or ion channel. The overall goal of this proposal is to understand in detail the biochemical mechanisms of action of the protein toxins in their interaction with the receptor protein and their functions of membrane insertion and ion channel activity. The specific aims of the present proposal are to identify the amino acids involved in receptor binding and ion channel functions of insecticidal toxins. Molecular, genetic, biochemical, and electrophysiological techniques such as site-directed mutagenesis, chemical modification, voltage clamping, and patch clamping will be used to probe toxin function. Knowledge gained from this project will provide an understanding of the mode of action of insecticidal crystal proteins in order to design more specific and more potent toxins against insect pests. The long range goal is to use this information to design better biopesticides against insect vectors of human disease.