Novel Catabolite Repression Pathway Controls Virulence in Streptococcus pyogenes

新型分解代谢物抑制途径控制化脓性链球菌的毒力

• 批准号: 7640841
• 负责人: Michael G. Caparon
• 金额: $ 33.55万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7640841
• 关键词: Aldehyde-Lyases; Anions; Bacterial Infections; Binding; Binding Proteins; Biochemical; Carbohydrates; Carbon; Catabolism; Chimera organism; Complement; Complex; Cues; Culture Media; Cysteine Protease; Data; Dominant-Negative Mutation; Environment; Enzymes; Evolution; Family; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Gram-Positive Bacteria; Growth; Human; In Vitro; Infection; Lac Operon; Lactose; Maps; Measures; Metabolic; Metabolism; Modeling; Molecular Profiling; Mus; Mutagenesis; Mutation; Nutritional; Outcome; Pathogenesis; Pathway interactions; Pattern; Peptides; Phase; Phenotype; Physiological; Play; Pseudogenes; Regulation; Regulator Genes; Regulatory Pathway; Repression; Research Personnel; Role; Signal Transduction; Specificity; Streptococcus pyogenes; Structure; Testing; Tissues; Transcription Coactivator; Virulence; Virulence Factors; base; in vivo; insight; member; mutant; novel; pathogen; programs; response; sensor; subcutaneous; sugar; tagatose

DESCRIPTION (provided by applicant): Numerous regulatory genes and environmental cues that influence Streptococcus pyogenes virulence gene regulation in vitro have been identified. However, very little is currently known as to how these signals are sensed, how different regulatory pathways interact and whether these cues are relevant in vivo. These are important questions, as differential regulation in response to compartment-specific cues may determine whether infection proceeds to a self-limiting or tissue-destructive outcome, an issue that is only very poorly understood for S. pyogenes. To gain insight into these questions, my lab has focused on regulation of speB, which encodes the secreted SpeB cysteine protease. We defined a set of in vitro conditions, including growth phase, pH, Cl- anion concentration and a carbohydrate-poor/peptide rich nutritional environment, that reflects expression patterns measured in vivo. Mutagenesis to identify a regulatory factor that could coordinate speB regulation in response to each of these cues resulted in the discovery of LacD.1, a tagatose aldolase that acts to repress speB transcription. Interestingly, S. pyogenes and several other Gram-positive pathogens contain two lactose operons (Lac.1 and Lac.2) where several of the genes encoding enzymes upstream of LacD.1, but not LacD.2, in the catabolic pathway are missing or are pseudogenes, suggesting that Lac.2 is involved in catabolism and that Lac.1 has evolved to a regulatory function. Consistent with this, LacD.2 has no regulatory phenotype and cannot complement the regulatory phenotype of LacD.1 and mutations that disrupt the catalytic center of LacD.1 do not alter its regulatory function; however, other mutations that may alter its ability to bind substrate do ablate regulation. Furthermore, we have shown that LacD.1 forms a complex in vivo with RopB, a DMA-binding protein and a known regulator of transcription and other metabolic genes. RopB is a member of the Rgg-family of transcription regulators broadly distributed among Gram-positive pathogens and virtually nothing is known about how this important family of regulators interacts with signal transduction systems. Based on examples of how other aldolases and sugar catabolic enzymes have been adapted to regulatory functions, these data suggest the following model for LacD.1 function: 1. That LacD.1 has been adapted as a sensor of intermediary metabolism; 2. That under carbohydrate-rich conditions, binding its substrate allows LacD.1 to act as an "anti-activator" and sequester RopB in an inactive form; 3. That LacD.1 may play a broader role in carbon catabolite repression and virulence gene expression; and 4. that LacD.1 is important for virulence. This project will explore these questions

描述（由申请人提供）：已经鉴定出了影响化脓性链球菌毒力基因调节体外的许多调节基因和环境线索。但是，目前对这些信号的感觉如何，不同的调节途径的相互作用以及这些提示在体内是否相关的知之甚少。这些是重要的问题，因为响应特定区域的提示的差异调节可能会决定感染是否会引起自限制或组织毁灭性结果，这对于pyogenes而言，这一问题只能理解。为了深入了解这些问题，我的实验室专注于SPEB的调节，SPEB编码了分泌的SPEB半胱氨酸蛋白酶。我们定义了一组体外条件，包括生长阶段，pH，Cl-阴离子浓度和碳水化合物贫困/肽富含营养环境，这些营养环境反映了体内测得的表达模式。诱变以识别可以根据这些提示进行协调SPEB调控的调节因子，从而发现了LACD.1。1，这是一种tagatose藻溶解酶，是一种可抑制SPEB转录的tagotose藻糖酶。 Interestingly, S. pyogenes and several other Gram-positive pathogens contain two lactose operons (Lac.1 and Lac.2) where several of the genes encoding enzymes upstream of LacD.1, but not LacD.2, in the catabolic pathway are missing or are pseudogenes, suggesting that Lac.2 is involved in catabolism and that Lac.1 has evolved to a regulatory function.与此相一致，LACD.2没有调节表型，不能补充LACD的调节表型和破坏LACD催化中心的突变。1不要改变其调节功能；但是，其他可能改变其结合底物能力的突变会消除调节。此外，我们已经证明LACD.1与ROPB，DMA结合蛋白以及已知的转录和其他代谢基因的调节剂形成一个复杂的体内体内。 ROPB是转录调节剂的RGG家庭的成员，广泛分布在革兰氏阳性病原体之间，几乎没有关于这个重要的调节剂家庭如何与信号转导系统相互作用的知识。基于其他醛糖酶和糖分解代谢酶如何适应调节功能的例子，这些数据表明了LACD函数的以下模型：1。lacd.1已将其作为中间代谢的传感器进行了调整。 2。在富含碳水化合物的条件下，结合其底物允许LACD.1充当“抗激活剂”，并以非活动形式隔离ROPB； 3。1 lacd.1可能在碳分解代谢物抑制和毒力基因表达中起更广泛的作用。和4。lacd.1对毒力很重要。这个项目将探讨这些问题