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）：发病机制可以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。对于许多病原体来说，一个关键的环境信号是营养物质的可用性。CodY是一种在几乎所有 低G +C革兰氏阳性菌是葡萄球菌、链球菌、梭菌、芽孢杆菌和李斯特菌中调节主要代谢途径和毒力基因表达以响应营养可用性的关键因子。CodY由GTP（链球菌除外）和支链氨基酸（异亮氨酸、亮氨酸和缬氨酸; BCAA）激活。当这些效应子的细胞内库减少时，CodY通常失去活性，并且它抑制的基因被打开。单核细胞增多症CodY是主要毒力调节因子PrfA的表达和活性所必需的。令人惊讶的是，CodY激活prfA转录结合prfA编码序列时，支链氨基酸是有限的。该提案旨在揭示CodY在prfA监管中反直觉作用的机制基础，同时将此类监管置于CodY全球作用的背景下。也就是说，预期响应CodY活性变化的数百个基因随着CodY效应物的细胞内库的变化而以分级方式表达。层次结构的分析将提供洞察细菌的策略，使用特定的代谢途径之前，其他和表达不同的毒力基因在不同水平的营养供应。此外，支链氨基酸已被证明在发病机制中具有复杂的作用。它们不仅是蛋白质的重要组成部分和CodY活性的效应子，而且是支链脂肪酸（BCFAs）的前体，而支链脂肪酸是L.单核细胞增生膜。用直链脂肪酸代替BCFA，可以得到L。单核细胞增多症通过涉及降低PrfA活性的机制毒性小得多。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。