Role of Listeria CodY in Integrating Metabolism and Virulence

李斯特菌 CodY 在整合代谢和毒力中的作用

• 批准号: 9247748
• 负责人: Anat A. Herskovits
• 金额: $ 57.31万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9247748
• 关键词: Affect; Anabolism; Animals; Bacillus (bacterium); Bacillus anthracis; Bacillus cereus; Bacteria; Binding; Binding Sites; Branched-Chain Amino Acids; Butyrates; Cells; Clostridium; Clostridium difficile; Code; Complex; Environment; Fatty Acids; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Genomics; Genus staphylococcus; Gram-Positive Bacteria; Growth; Guanosine Triphosphate; Human; Immune system; In Vitro; Infection; Intestines; Isoleucine; Laboratories; Laboratory culture; Leucine; Link; Listeria; Listeria monocytogenes; Mediating; Membrane; Metabolic; Metabolic Pathway; Metabolism; Modeling; Molecular; Mus; Mutation; Nutrient; Pathogenesis; Pathway interactions; Phase; Play; Process; Proteins; Regulation; Regulon; Residual state; Role; Signal Transduction; Staphylococcus aureus; Streptococcus; Streptococcus pyogenes; Symbiosis; Testing; Time; Toxin; Transaminases; Transcript; Transcription Coactivator; Valine; Virulence; Virulence Factors; Virulent; Work; bacterial metabolism; branched chain fatty acid; capsule; detection of nutrient; fatty acid metabolism; foodborne pathogen; genetic regulatory protein; in vivo; insight; killings; macrophage; mutant; novel; nutrient deprivation; overexpression; pathogen; pathogenic bacteria; public health relevance; response; therapeutic target; transcriptome sequencing

DESCRIPTION (provided by applicant): Pathogenesis can be viewed as a strategic response of bacteria to environmental conditions they encounter in a human or animal host. For many pathogens, a key environmental signal is nutrient availability. CodY, a protein found in nearly all low-G+C Gram-positive bacteria, is a key factor that regulates major metabolic pathways and virulence gene expression in response to nutrient availability in Staphylococcus, Streptococcus, Clostridium, Bacillus and Listeria. CodY is activated by GTP (except in Streptococcus) and the branched-chain amino acids (isoleucine, leucine and valine; BCAAs). When the intracellular pools of these effectors decrease, CodY generally loses activity and genes that it represses are turned on. Our recently acquired evidence indicates that L. monocytogenes CodY is necessary for expression and activity of the major virulence regulator, PrfA. Surprisingly, CodY activates prfA transcription by binding within the prfA coding sequence when BCAAs are limiting. This proposal aims to unravel the mechanistic basis for the counterintuitive role of CodY in prfA regulation, while at the same time placing such regulation in the context of the global role of CodY. That is, the hundreds of genes that respond to changes in CodY activity are expected to be expressed in a hierarchical manner as the intracellular pools of the CodY effectors change. The analysis of the hierarchy will provide insight into the bacterium's strategy for using particulr metabolic pathways ahead of others and for expressing different virulence genes at different levels of nutrient availability. In addition, the BCAAs have been shown to have a complex role in pathogenesis. They are not only key components of proteins and effectors of CodY activity, but are also the precursors for the branched-chain fatty acids (BCFAs) that are the major constituents of L. monocytogenes membranes. Substituting straight-chain fatty acids for the BCFAs makes L. monocytogenes much less virulent by a mechanism that involves reducing PrfA activity. Since CodY represses BCAA biosynthesis and activates prfA transcription, understanding the mechanism by which CodY brings about the appropriate level of PrfA activity will give important new insight into the integration of metabolism and virulence as well as the infection process as a whole.

描述（由申请人提供）：发病机理可被视为细菌对它们在人类或动物宿主中遇到的环境条件的战略反应。对于许多病原体，关键的环境信号是养分的可用性。科迪，几乎所有的蛋白质 低-G+C革兰氏阳性细菌是调节葡萄球菌，链球菌，梭状芽胞杆菌，杆菌和李斯特菌的养分可利用率的主要代谢途径和毒力基因表达的关键因素。 Cody被GTP（链球菌除外）和分支链氨基酸（异亮氨酸，亮氨酸和Valine； BCAA）激活。当这些效应子的细胞内池减少时，Cody通常会失去其抑制作用的活性和基因。我们最近获得的证据表明，单核细胞增生李斯特氏菌Cody对于主要毒力调节剂PRFA的表达和活性是必需的。令人惊讶的是，当BCAA受到限制时，Cody通过在PRFA编码序列中结合来激活PRFA转录。该提案旨在揭示科迪在PRFA调节中的违反直觉作用的机理基础，同时将这种调节放在Cody的全球作用背景下。也就是说，随着Cody效应子的细胞内池的变化，预计Cody活性变化的数百个基因将以层次的方式表达。对层次结构的分析将洞悉该细菌在其他人之前使用特定代谢途径的策略，并在不同水平的养分可用性下表达不同的毒力基因。另外，BCAA在发病机理中已显示出复杂的作用。它们不仅是Cody活性的蛋白质和效应子的关键成分，而且还是分支链脂肪酸（BCFA）的前体，它们是单核细胞增生乳杆菌膜的主要成分。将直链脂肪酸取代BCFAS，通过涉及降低PRFA活性的机制，单核细胞增生乳杆菌的毒性要小得多。由于Cody抑制BCAA生物合成并激活PRFA转录，因此了解Cody带来适当水平的PRFA活性水平的机制将为代谢和毒力的整合以及整个感染过程提供重要的新见解。