Peptide autoinducers of staphylococcal pathogenicity.

描述(申请人提供)：agr基因座编码葡萄球菌致病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，以及一个由agrD编码的多肽自动诱导剂(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。这是一项长期计划的继续，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变异体及其生物型的生物学意义。这一时期的具体目标是：1.确定多肽的分泌、结合、激活和抑制的机制。2.明确AGR系统的信号转导机制。3.确定AGR抑制剂的治疗潜力。设计与方法。将使用遗传和生化方法来确定AIP的分泌机制。直接配基结合分析将用于分析受体与配基的相互作用。具体的配体结合部位将通过诱变和交联研究来确定；受体的激活机制将通过突变和结构研究来确定。结构活性受体突变体将成为体外机制研究的重要工具。对反向激活性耐药的突变体将被分离和分析，以检验存在特定的抑制性接触和激活接触的假设。这一假设将得到检验，即在远端部位给予抑制性AIP可以阻止实验性感染的建立，或者如果在感染建立之后给予，可以减轻或根除感染。 公共卫生相关性：金黄色葡萄球菌长期以来一直是医院的祸害，它已经以增强的毒力和高传染性入侵外部社区。我们的项目旨在了解该有机体的病理生物学，并学习如何通过干扰一个关键的细菌信号系统的功能来阻止其致病能力，该系统激活毒素和其他有害物质的产生。

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.