Mechanistic Dissection of Pheromone-Dependent Regulation of Group A Streptococcal

A 组链球菌信息素依赖性调节的机制剖析

• 批准号: 8683085
• 负责人: MICHAEL J FEDERLE
• 金额: $ 39.25万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8683085
• 关键词: Animals; Bacterial Genes; Binding; Biological Assay; Cell Communication; Cells; Chromatography; Communication; Cysteine Protease; DNA; Data; Disease; Dissection; Foundations; Future; Gene Expression; Gene Expression Regulation; Genetic; Genetic Screening; Genetic Transcription; Goals; Gram-Positive Bacteria; Growth; In Vitro; Infection; Luciferases; Modeling; Mutagenesis; Organism; Orthologous Gene; Pathogenesis; Pathway interactions; Pattern; Peptide Hydrolases; Peptide Signal Sequences; Peptides; Phase; Pheromone; Play; Process; Production; Property; Proteins; Regulation; Regulatory Pathway; Research; Role; Severity of illness; Signal Transduction; Streptococcus; Streptococcus pyogenes; Structure; System; Systemic infection; Testing; Virulence; Virulence Factors; antimicrobial; base; design; environmental change; in vivo; insight; paralogous gene; pathogen; quorum sensing; research study; response; reversed phase chromatography; therapy design/development; transcription factor

DESCRIPTION (provided by applicant): Group A Streptococcus (GAS), a pathogen capable of both localized and systemic infection, is known to secrete numerous virulence factors in temporal patterns during growth in vitro and in vivo, indicating the presence of intricate regulatory circuits. An inverse relationship exists between expression levels of the secreted cysteine protease, SpeB, and severity of disease [1-3]. The so-called "stand-alone" regulator Rgg (also known as RopB) is required, but is not sufficient, for expression of SpeB. An unknown growth-phase-dependent factor is additionally required, but has remained elusive [4-6]. Our preliminary data demonstrate that the unknown factor is a bacterially-produced pheromone with properties consistent with a small peptide. Additionally, analysis predicts that Rgg is a peptide-binding transcription factor with structural homology to PlcR and PrgX of other quorum sensing systems. The overall hypothesis to be tested is that a pheromone modulates the activity of Rgg for the purpose of controlling speB transcription. This is a departure from the paradigm that the Rgg-dependent pathway responds to environmental changes; instead, we provide compelling evidence that GAS produces its own impetus to induce speB. Our preliminary results demonstrate that Rgg paralogs found in GAS are indeed responsive to small peptide pheromones, providing a convincing precedent for our hypothesis and are the first examples that Rgg proteins are quorum sensing effectors. The goal of our research will be to define the signaling pheromone(s) present in culture supernatants and characterize the mechanism for its production and recognition by GAS. Genetic disruption of these systems will be tested for their contributions in localized and invasive infection models. Demonstration that GAS utilizes Rgg proteins for cell-to-cell signaling will provide a foundation for future development of therapies designed to interfere with intercellular signaling in GAS and in other Rgg-containing organisms.

描述（由申请人提供）：A 族链球菌 (GAS) 是一种能够局部和全身感染的病原体，已知在体外和体内生长期间以时间模式分泌大量毒力因子，表明存在复杂的调节回路。分泌型半胱氨酸蛋白酶 SpeB 的表达水平与疾病严重程度之间存在负相关关系 [1-3]。所谓的“独立”调节器 Rgg（也称为 RopB）对于 SpeB 的表达是必需的，但还不够。另外还需要一个未知的生长阶段依赖因子，但仍然难以捉摸[4-6]。我们的初步数据表明，未知因子是细菌产生的信息素，其特性与小肽一致。 此外，分析预测Rgg是一种肽结合转录因子，与其他群体感应系统的PlcR和PrgX具有结构同源性。要测试的总体假设是信息素调节 Rgg 的活性以控制 speB 转录。这背离了 Rgg 依赖性途径响应环境变化的范式；相反，我们提供了令人信服的证据，证明 GAS 会产生自己的动力来诱发 speB。我们的初步结果表明，在 GAS 中发现的 Rgg 旁系同源物确实对小肽信息素有反应，为我们的假设提供了令人信服的先例，并且是 Rgg 蛋白是群体感应效应器的第一个例子。我们研究的目标是确定培养物上清液中存在的信号信息素，并表征其产生和 GAS 识别的机制。将测试这些系统的基因破坏在局部和侵入性感染模型中的贡献。 GAS 利用 Rgg 蛋白进行细胞间信号传导的证明将为未来开发旨在干扰 GAS 和其他含有 Rgg 的生物体中细胞间信号传导的疗法奠定基础。