FUNCTINAL DOMAINS OF BACCILLUS THURINGIENSIS ENDOTOXINS

苏云金芽孢杆菌是一种微生物杀虫剂，广泛用于 控制许多昆虫，包括农业害虫；以及蚊子 以及传播人类疾病的黑蝇。活性成分为 杀虫晶体蛋白或Cry毒素。这些杀虫药 蛋白质可以通过基因工程和蛋白质工程来操纵 改变和提高他们的活动能力。 本项目的总体目标是详细调查 几种Cry毒素对已知受体的作用及提高杀虫效果的研究 通过改善与受体的结合而发挥活性。具体目标 是为了确定Cry毒素上相互作用的氨基酸残基 并通过实验改变这些残基来识别 这些取代残基增强了结合力和毒性。这将是 通过定点突变的基因技术完成。 受体上负责相互作用的成分 与毒素的关系也将通过生化方法进行测定。建议数 研究采用了一种由已知的哭泣毒素组成的模型系统 结构作为一种特性良好的受体。当基本的 了解了毒素-受体的相互作用，这可能会用于 改善Cry毒素对蚊子的作用。

Bacillus thuringiensis is a microbial insecticide that is widely used to control numerous insects, including agricultural pests; and, mosquitoes and blackflies, vectors of human diseases. The active components are the insecticidal crystal proteins or Cry toxins. These insecticidal proteins may be manipulated by genetic and protein engineering to alter and improve their activity. The overall goal of this project is to investigate in detail the binding of several Cry toxins to a known receptor and improve the insecticidal activity by improving the binding to the receptor. The specific aims are to identify the amino acid residues on the Cry toxins that interact with the receptor and to experimentally alter these residues to identify which substituted residues enhance binding and toxicity. This will be accomplished by the genetic technique of site-directed mutagenesis. The components on the receptor that are responsible for interaction with the toxin will also be determined biochemically. The proposed research employs a model system consisting of a cry toxins of known structure as a well characterized receptor. When the basic understanding of toxin-receptor interaction is obtained, this may used to improve Cry toxins against the mosquito.