FUNCTIONAL DOMAINS OF BACILLUS THURINGIENSIS ENDOTOXIN

苏云金芽孢杆菌是一种有效的微生物杀虫剂， 用于控制农业害虫，蚊子和黑蝇， 是人类疾病的传播媒介 活性杀虫成分为 δ-内毒素，其特异性不同，但被认为具有 类似的行动方式。 它们从原毒素形式加工成 昆虫中肠中的蛋白酶释放活性毒素。 活性毒素结合 并通过形成孔或离子通道引起细胞溶解。 本提案的总体目标是详细了解 蛋白质毒素在其体内作用的生化机制 与受体蛋白的相互作用及其膜功能 插入和离子通道活性。 本提案的具体目标是鉴定氨基酸 参与杀虫剂的受体结合和离子通道功能 毒素分子、遗传、生物化学和电生理学 例如定点诱变，化学修饰， 电压箝位和膜片钳将用于探测毒素功能。 从这个项目中获得的知识将提供对 杀虫晶体蛋白的作用模式，以设计更多 针对害虫的特异性和更有效的毒素。 长期目标 就是利用这些信息来设计更好的生物杀虫剂来对付昆虫 人类疾病的传播媒介。

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.