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，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，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。确定自诱导肽生物合成的机制和成熟分泌肽与受体相互作用的机制，包括同源肽的激活和异源肽的抑制。2. 通过跟踪体内特定基因的表达、某些突变的后果以及诱导或抑制肽对实验性感染过程的影响，确定agr系统在葡萄球菌疾病发病机制中的作用。3. 描述agr特异性群体的特征或基因，这些特征或基因在一个群体内共享，在群体之间不同，关于生物体的致病适应性。设计和方法：使用放射性肽的直接配体结合试验将用于分析受体与配体的相互作用。变异肽将被合成以描述受体激活和抑制的结构和序列要求。其他变体将被合成以提高体内稳定性和活性，以最大限度地提高抑制毒力的治疗效果。某些细菌基因将融合到荧光素酶报告基因中，这将允许通过荧光素酶检测成像摄像机监测它们的表达以及在小鼠感染模型中感染生物体的命运和持久性。该摄像机将监测体内agr抑制对感染生物体和体内基因表达的影响。将描述Agr群体特异性生物型，以确定可能与致病行为相关的群体特异性特征-病变部位和类型，毒力水平，抗生素耐药性等。

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, 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, and the biological significance of agr variants and their biotypes. Specific Aims for this period are: 1. To determine the mechanism of autoinducing peptide biosynthesis and the mechanism by which the mature secreted peptide interacts with its receptor, including both activation by cognate peptides and inhibition by heterologous ones. 2. To determine the role of the agr system in the pathogenesis of staphylococcal disease by following the expression of specific genes in vivo, the consequences of certain mutations, and the effects of the inducing or inhibiting peptides on the course of an experimental infection. 3. To characterize the agr specificity groups for traits or genes that are shared within a group and divergent between groups, with respect to pathogenic adaptations of the organism. Design and Methods: A direct ligand-binding assay using radioactive peptide will be developed to analyze receptor-ligand interactions. Variant peptides will be synthesized to delineate the structural and sequence requirements for receptor activation and inhibition. Other variants will be synthesized to enhance stability and activity in vivo to maximize the therapeutic efficacy of inhibiting virulence. Certain bacterial genes will be fused to a luciferase reporter, which will permit the monitoring of their expression as well as of the fate and persistence of infecting organisms in a murine infection model, by means of a luciferase-detecting imaging camera. This camera will monitor the effects of in vivo agr inhibition on the infecting organisms and on gene expression in vivo. Agr group-specific biotypes will be delineated to identify group-specific traits that may be correlated with pathogenic behavior - site and type of lesion, level of virulence, antibiotic resistance, etc..