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: 9042310
• 负责人: Anat A. Herskovits
• 金额: $ 53.81万
• 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/9042310
• 关键词: Accounting; 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; Health; Human; Immune system; In Vitro; Infection; Intestines; Isoleucine; Laboratories; Laboratory culture; Leucine; Life; 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; Testing; Time; Toxin; Transaminases; Transcript; Transcription Coactivator; Valine; Virulence; Virulence Factors; Virulent; Work; bacterial metabolism; base; 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; 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性反应。对于许多病原体来说，一个关键的环境信号是养分的可用性。Cody，一种在几乎所有的 低G+C革兰氏阳性菌是调节葡萄球菌、链球菌、梭状芽孢杆菌、芽孢杆菌和李斯特菌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)和支链氨基酸(异亮氨酸、亮氨酸和缬氨酸；支链氨基酸)激活。当这些效应器的细胞内池减少时，Cody通常会失去活性，它抑制的基因被激活。我们最近获得的证据表明，单核细胞增多性李斯特菌Cody是主要毒力调节因子PrFA表达和活性所必需的。令人惊讶的是，当支链氨基酸受到限制时，Cody通过与PRFA编码序列结合来激活PRFA转录。这项建议旨在揭开科迪在PRFA监管中违反直觉的作用的机制基础，同时将这种监管置于科迪的全球角色的背景下。也就是说，随着Cody效应器细胞内池的变化，数百个对Cody活性变化做出反应的基因预计将以分级方式表达。对层次结构的分析将深入了解细菌先于其他细菌使用特定代谢途径的策略，以及在不同营养可获得性水平上表达不同毒力基因的策略。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关键成分和Cody活性的效应者，而且也是支链脂肪酸(BCFAs)的前体，支链脂肪酸是单核细胞增多性乳杆菌膜的主要成分。用直链脂肪酸取代BCFAs，通过降低PRFA活性的机制，使单核细胞增多性乳杆菌的毒力大大降低。由于Cody抑制BCAA的生物合成并激活PRFA的转录，了解Cody导致适当水平的PRFA活性的机制将对新陈代谢和毒力的整合以及整个感染过程提供重要的新见解。