Control of virulence in Vibrio cholerae by fatty acids

通过脂肪酸控制霍乱弧菌的毒力

• 批准号: 9174511
• 负责人: Fredrick Jon Kull
• 金额: $ 37.13万
• 依托单位: DARTMOUTH COLLEGE
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9174511
• 关键词: 5' Untranslated Regions; Acids; Address; Adult; Affect; Bacterial Infections; Beryllium; Bicarbonates; Bile fluid; Binding; Cessation of life; ChIP-seq; Child; Cholera; Cholera Toxin; Communication; Complex; DNA; DNA Binding; DNA Binding Domain; Data; Development; Dimerization; Disease; Enteral; Environment; Epidemic; Factor V; Family; Fatty Acids; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Goals; Gram-Negative Bacterial Infections; Hour; Human; Hybrids; Laboratories; LacZ Genes; Lead; Length; Ligands; Light; Link; Mediating; Mission; Modeling; Molecular; Mutation; N-terminal; Nucleotides; Pathogenesis; Pathway interactions; Persons; Pharmaceutical Preparations; Pilum; Play; Prevention; Process; Proteins; RNA; Regulation; Regulatory Element; Research; Rhamnose; Ribosomes; Role; Signal Transduction; Stimulus; Stomach; Structure; Testing; Thermometers; Toxin; Transcriptional Activation; Translations; United States National Institutes of Health; Unsaturated Fatty Acids; Untranslated Regions; Vaccines; Vibrio cholerae; Vibrio cholerae O1; Virulence; Virulence Factors; Virulent; Work; base; drug discovery; fatty acid metabolism; in vivo; insight; killings; member; monomer; mutant; novel therapeutic intervention; pandemic disease; pathogenic bacteria; prevent; promoter; research study; small molecule; stem; structural biology; transcriptome sequencing

Vibrio cholerae O1 causes the fatal epidemic disease cholera. The ability of V. cholerae to cause disease in humans is dependent upon two primary virulence factors, the toxin-coregulated pilus (TCP), a critical colonization factor, and cholera toxin (CT). The expression of these factors is controlled by a highly regulated transcriptional cascade that serves as a paradigm for the regulation of bacterial virulence. Expression of the cascade is initiated at the tcpPH promoter by a cooperative interaction between the regulators AphA and AphB. TcpPH and ToxRS are homologous pairs of transmembrane regulators that then cooperate to activate expression from the toxT promoter. ToxT, an AraC-type regulator, directly activates the expression of TCP and CT. Transcriptional activation of the virulence cascade is strongly dependent upon a variety of stimuli from the external environment. The long-term goals of this proposal are to understand the molecular basis of virulence gene regulation in V. cholerae so as to facilitate the development of new strategies to control its infectivity. Through a collaborative effort involving laboratories with expertise in structural biology, virulence gene regulation and pathogenesis, we have found that exogenous unsaturated fatty acids (UFAs), which are components of human bile, are capable of binding to ToxT and impairing its ability to activate virulence gene expression. UFAs bind into a ligand pocket in the N-terminal domain of ToxT and inhibit its dimerization as well as its ability to bind to DNA. Bicarbonate, which neutralizes the acid that comes from the stomach, has been shown to function as a second in vivo signal that, in contrast to UFAs, stimulates ToxT and enhances its DNA binding through an unknown mechanism. We have recently identified a new link between fatty acids (FAs) and virulence gene expression in the current pandemic strain of V. cholerae with the discovery that the master regulator of FA metabolism, FadR, influences the translation of ToxT by an unknown mechanism. This proposal will build upon the ToxT structural and functional data, as well as our recent studies involving FadR, in order to elucidate several key mechanisms involved in regulating the expression of the virulence cascade. In Aim 1, we propose to elucidate the allosteric mechanisms controlling the dimerization of ToxT and to investigate the opposing effects of UFAs and bicarbonate on this process. In Aim 2, we propose to elucidate the mechanism by which FadR influences the translation of ToxT in V. cholerae. These studies will contribute significantly toward our understanding of how virulence gene expression is regulated in V. cholerae and will likely provide new avenues for antivirulence drug discovery.

弧菌霍乱O1引起致命的流行病霍乱。 V.霍乱造成的能力 人类的疾病取决于两个主要的毒力因子，即毒素调节的菌毛（TCP），A 临界定植因子和霍乱毒素（CT）。这些因素的表达由高度控制 调节的转录级联反应是调节细菌毒力的范式。 级联的表达是在TCPPH启动子上通过合作相互作用启动的 监管机构APHA和APHB。 TCPPH和TOXR是跨膜调节剂的同源对，然后 合作以激活TOXT启动子的表达。 TOXT，ARAC型调节器，直接激活 TCP和CT的表达。毒力级联的转录激活很大程度上取决于 外部环境的各种刺激。该提议的长期目标是了解 毒性基因调节的分子基础在霍乱弧菌中，以促进新的发展 控制其感染力的策略。通过涉及具有专业知识的实验室的合作努力 结构生物学，毒力基因调节和发病机理，我们发现外源不饱和 脂肪酸（UFA）是人类胆汁的组成部分，能够与TOXT结合并损害其 激活毒力基因表达的能力。 UFA结合到TOXT的N末端域中的配体袋 并抑制其二聚化以及与DNA结合的能力。碳酸氢盐，中和酸 来自胃，已显示起到第二个体内信号的作用，与UFA相比， 通过未知机制刺激TOXT并增强其DNA结合。我们最近确定了 V. Cholerae的当前大流行菌株中脂肪酸（FAS）和毒力基因表达之间的新联系 随着发现FA代谢的主要监管者Fadr影响了Toxt的翻译 未知机制。该建议将基于TOXT结构和功能数据以及我们的 最近涉及FADR的研究，以阐明与调节有关的几种关键机制 毒力级联反应的表达。在AIM 1中，我们建议阐明控制的变构机制 TOXT的二聚化并研究UFA和碳酸氢盐对此过程的相反作用。在 AIM 2，我们建议阐明FADR影响VTT在V中的翻译的机制。 霍乱。这些研究将对我们对毒力基因的理解做出重大贡献 表达受到霍乱弧菌的调节，可能会为抗毒素药物发现提供新的途径。