Quorum Sensing in Group B Streptococcus

B 族链球菌中的群体感应

• 批准号: 7140528
• 负责人: MICHAEL John CIESLEWICZ
• 金额: $ 20.63万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7140528
• 关键词: Streptococcus agalactiae; animal mortality; bacteria infection mechanism; bacterial genetics; bacterial meningitis; bacterial proteins; biological signal transduction; fusion gene; gene deletion mutation; gene expression; genetic regulation; genetically modified animals; host organism interaction; laboratory mouse; microarray technology; molecular genetics; opportunistic infections; polymerase chain reaction; quorum sensing; reporter genes; virulence

DESCRIPTION (provided by applicant): Group B Streptococcus (Streptococcus agalactiae or GBS) is the leading cause of gram positive neonatal meningitis and is an increasingly important cause of serious infection in elderly and chronically ill adults. Although GBS usually behaves as a harmless commensal colonizing the gastrointestinal and genital tracts of nearly a third of adult women, it has the capacity to produce life-threatening infection in susceptible hosts. The factors associated with the transition of GBS from harmless commensal to invasive pathogen are not known but are likely to involve a repertoire of bacterial mechanisms that respond to specific cues encountered in various host environments. It has been speculated that gram-positive and gram-negative bacteria utilize a density-dependent sensing mechanism (termed "quorum sensing") through secretion of a LuxS dependent AI-2 signaling molecule that communicates with other organisms as well as regulates bacterial gene expression. We have identified and constructed a non-polar deletion mutant in a LuxS homolog in GBS. The luxS deletion mutant produces decreased bioluminescence in an AI-2 reporter strain of Vibrio harveyi compared to the wild type parent strain suggesting that GBS is capable of responding to the LuxS dependent AI-2 signaling molecule. The overall objectives of this proposal are to (1) determine the array of GBS genes regulated by the LuxS dependent AI-2 signaling molecule as well as determine the contribution of the AI-2 molecule to GBS virulence and (2) determine the molecular mechanism by which the LuxS dependent AI-2 signaling molecule regulates GBS gene expression. These objectives will be achieved by (A) comparing the transcriptisomes of wild type GBS and an isogenic luxS deletion mutant by microarray analysis followed by mouse lethality studies to assess the contribution of AI-2 to virulence and (B) constructing reporter fusions in genes regulated in response to the LuxS dependent AI-2 signaling molecule to determine if gene regulation is achieved by extracellular accumulation of a LuxS dependent AI-2 molecule.

描述（由申请人提供）：B 族链球菌（无乳链球菌或 GBS）是革兰氏阳性新生儿脑膜炎的主要原因，并且是老年人和慢性病成人严重感染的日益重要的原因。尽管 GBS 通常表现为一种无害的共生菌，寄居在近三分之一成年女性的胃肠道和生殖道中，但它有能力在易感宿主中产生危及生命的感染。与 GBS 从无害共生菌转变为侵入性病原体相关的因素尚不清楚，但可能涉及一系列细菌机制，这些机制对各种宿主环境中遇到的特定信号做出反应。据推测，革兰氏阳性和革兰氏阴性细菌通过分泌依赖于 LuxS 的 AI-2 信号分子来利用密度依赖性传感机制（称为“群体感应”），该信号分子与其他生物体进行通信并调节细菌基因表达。我们在 GBS 的 LuxS 同源物中鉴定并构建了非极性缺失突变体。与野生型亲本菌株相比，luxS 缺失突变体在哈维氏弧菌的 AI-2 报告菌株中产生的生物发光减少，表明 GBS 能够响应 LuxS 依赖性 AI-2 信号分子。该提案的总体目标是（1）确定由 LuxS 依赖性 AI-2 信号分子调节的 GBS 基因阵列，以及确定 AI-2 分子对 GBS 毒力的贡献，以及（2）确定分子机制LuxS 依赖性 AI-2 信号分子通过其调节 GBS 基因表达。这些目标将通过以下方式实现：(A) 通过微阵列分析比较野生型 GBS 和同基因 luxS 缺失突变体的转录体，然后进行小鼠致死性研究以评估 AI-2 对毒力的贡献；以及 (B) 在受调控基因中构建报告融合体响应 LuxS 依赖性 AI-2 信号分子，以确定基因调控是否通过 LuxS 依赖性 AI-2 分子的细胞外积累来实现。