SHIGELLA TOXIN: STRUCTURE AND FUNCTION RELATIONSHIPS

我们的假设是，一种无细胞蛋白毒素在 志贺氏菌感染的发病机制。 这种毒素可能是造成 临床表现为水泻和痢疾。 一 基本了解毒素介导其 生物效应将有助于开发改进的治疗方法， 治疗方案和安全有效的疫苗株。 研究 志贺氏菌毒素的作用机制，我们将研究毒素介导的 抑制蛋白质合成。 使用无细胞系统， 确定蛋白质合成的具体生化步骤是什么 被毒素抑制了 我们将采用各种方法对蛋白质和RNA 分离和表征，以研究实际的毒素催化 导致蛋白质合成抑制的核糖体改变。 使用体内和体外系统，我们将确定毒素是否 抑制小肠腔内蛋白质的合成。 通过使用 细胞分离技术，毒素对各种细胞的影响， 将确定肠腔的组分。 最后由 分离A和B链，并通过使用单克隆抗体定向 针对毒素链，我们将研究这些链在 毒素的各种生物活性 除了明确 毒素在发病机制中的作用，这些研究也应该提供一些 关于真核生物的结构和功能的基本信息 核糖体

Our hypothesis is that a cell free protein toxin plays a critical role in pathogenesis of Shigella infections. The toxin may be responsible for both clinical manifestations of the disease, watery diarrhea and dysentery. A basic understanding of the mechanisms by which the toxin mediates its biological effects will aid in the development of improved therapeutic treatment programs and of safe and effective vaccine strains. To study the mechanism of action of Shigella toxin we will investigate toxin mediated inhibition of protein synthesis. Using a cell free system we will determine specifically what biochemical step in protein synthesis is inhibited by the toxin. We will employ various methods for protein and RNA separation and characterization to investigate the actual toxin catalyzed ribosomal alteration which leads to the protein synthesis inhibition. Using both in vivo and in vitro systems we will determine whether toxin inhibits protein synthesis in the lumen of the small intestine. By using cell separation techniques, the effects of toxin on the various cell components of the intestinal lumen will be determined. Finally by separating A and B chains and by using monoclonal antibodies directed against the toxin chains we will investigate the role of these chains in the various biological activities of the toxin. In addition to clarifying the role of toxin in pathogenesis, these studies should also provide some basic information concerning the structure and function of the eukaryotic ribosome.