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节系统。它是一个群体感应系统，包含由 agrA 和 C 编码的双组分信号转导模块，以及由 agrD（即激活配体）编码的肽自诱导剂 (AIP)。存在天然变体，它们在异源组合中交叉抑制 agr 自诱导，从而阻断发病机制。这是一个长期计划的延续，其总体目标是了解 agr 自诱导机制、agr 自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. 确定肽分泌、结合、激活和抑制的机制。 2. 确定agr系统中的信号转导机制。 3.确定agr抑制的治疗潜力。设计和方法。将使用遗传和生化方法来确定AIP分泌的机制。直接配体结合测定将用于分析受体-配体相互作用。将通过诱变和交联研究来鉴定特定的配体结合位点；受体激活的机制将通过突变和结构研究来确定。组成型活性受体突变体将成为体外机制研究的重要工具。对反向激动具有抗性的突变体将被分离和分析，以检验存在特定抑制接触和激活接触的假设。将测试以下假设：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。 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，现已以更强的毒力和高传染性侵入外部社区。我们的项目旨在了解生物体的病理学，并学习如何通过干扰激活毒素和其他有害物质产生的关键细菌信号系统的功能来阻止其致病能力。

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.