Peptide autoinducers of staphylococcal pathogenicity.

描述（由申请人提供）：agr基因座编码葡萄球菌发病机制和其他应激相关功能的中央调控系统。它是一个群体感应系统，包含一个由agrA和C编码的双组分信号转导模块和一个由agrD编码的肽自诱导剂（AIP），即激活配体。在异源组合中存在交叉抑制agr自身诱导的自然变异，从而阻断发病机制。这是一个长期项目的延续，其总体目标是了解agr自身诱导的机制，agr自身诱导回路在葡萄球菌疾病发病机制中的作用，agr抑制的治疗潜力，以及agr变体及其生物型的生物学意义。这一时期的具体目标是：1。确定多肽分泌、结合、激活和抑制的机制。2. 确定agr系统信号转导的机制。3. 确定agr抑制的治疗潜力。设计和方法。遗传学和生物化学方法将用于确定AIP分泌的机制。直接配体结合试验将用于分析受体-配体相互作用。特异性配体结合位点将通过诱变和交联研究确定；受体激活的机制将通过突变和结构研究来确定。组成活性受体突变体将是体外机制研究的重要工具。将分离并分析抗逆激动作用的突变体，以验证存在特定抑制接触和激活接触的假设。该假设将得到验证，即在远端部位施用抑制性AIP可以阻止实验性感染的建立，或者如果在感染建立后施用，可以减弱或根除感染。

DESCRIPTION (provided by applicant): The agr locus encodes the central regulatory system for staphylococcal pathogenesis and other stress-related functions. It is a quorum-sensing system that contains a two-component signal transduction module, encoded by agrA and C, and a peptide autoinducer (AIP), encoded by agrD, that is the activating ligand. Natural variants exist that cross inhibit agr autoinduction in heterologous combinations, thus blocking pathogenesis. This is the continuation of a long-term program whose overall goal is to understand the mechanism of agr autoinduction, the role of the agr autoinduction circuit in the pathogenesis of staphylococcal disease, the therapeutic potential of agr inhibition, and the biological significance of agr variants and their biotypes. Specific Aims for this period are: 1. To determine mechanisms of peptide secretion, binding, activation and inhibition. 2. To determine the mechanism of signal transduction in the agr system. 3. To determine the therapeutic potential of agr inhibition. Design and Methods. Genetic and biochemical methods will be used to determine the mechanism of AIP secretion. A direct ligand-binding assay will be used to analyze receptor-ligand interactions. Specific ligand binding sites will be identified by mutagenesis and cross-linking studies; the mechanism of receptor activation will be determined by mutational and structural studies. Constitutively active receptor mutants will be an important tool in vitro mechanistic studies. Mutants resistant to inverse agonism will be isolated and analyzed to test the hypothesis that there are specific inhibitory contacts as well as activating contacts. The hypothesis will be tested that administration of an inhibitory AIP at a distal site can block the establishment of an experimental infection, or if administered after an infection has been established, can attenuate or eradicate the infection. PUBLIC HEALTH RELEVANCE: Staphylococcus aureus, long a scourge of the hospital, has invaded the outside community with enhanced virulence and high contagion. Our project is aimed at understanding the pathobiology of the organism and learning how to block its ability to cause disease by interfering with the function of a key bacterial signaling system that activates the production of toxins and other detrimental substances.