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其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，关键的环境信号是营养物质的可用性。 CodY，一种几乎存在于所有物质中的蛋白质 低 G+C 革兰氏阳性菌是调节主要代谢途径和毒力基因表达以响应葡萄球菌、链球菌、梭菌、芽孢杆菌和李斯特菌中营养可用性的关键因素。 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。当这些效应子的细胞内池减少时，CodY 通常会失去活性，并且它抑制的基因会被打开。我们最近获得的证据表明，单增李斯特菌 CodY 对于主要毒力调节因子 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 通过与 prfA 编码序列结合来激活 prfA 转录。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，随着 CodY 效应子的细胞内库的变化，预计对 CodY 活性变化做出反应的数百个基因将以分层方式表达。对层次结构的分析将深入了解细菌的策略，即先于其他途径使用特定的代谢途径，并在不同的营养可用性水平下表达不同的毒力基因。此外，BCAA 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 活性的效应子，而且还是支链脂肪酸 (BCFA) 的前体，而支链脂肪酸是单核细胞增生李斯特菌膜的主要成分。用直链脂肪酸替代 BCFA 可以通过降低 PrfA 活性的机制大大降低单核细胞增生李斯特菌的毒力。由于 CodY 抑制 BCAA 生物合成并激活 prfA 转录，了解 CodY 带来适当水平 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。