Sugar Regulation of EHEC virulence

肠出血性大肠杆菌毒力的糖调节

• 批准号: 8702080
• 负责人: VANESSA SPERANDIO
• 金额: $ 39.75万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-19 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8702080
• 关键词: Address; Affect; Attenuated; Bacterial Adhesins; Bacteroides thetaiotaomicron; Binding; Carbon; Complex; Cues; Ensure; Enterocytes; Environment; Escherichia coli EHEC; Fucose; Gene Expression; Gene Expression Regulation; Genes; Grant; Growth; Hormones; Infection; Intestines; Invaded; Investigation; Lesion; Membrane; Metabolism; Mucous body substance; Names; Nutrient; Pathogenicity; Pathogenicity Island; Phosphotransferases; Regulation; Signal Transduction; Source; System; Virulence; Virulence Factors; attenuation; enteric pathogen; gastrointestinal; gastrointestinal bacteria; gut microbiota; in vivo; member; mutant; novel; nutrition; pathogen; public health relevance; response; sensor; sensor histidine kinase; sugar; trait; transcription factor

DESCRIPTION (provided by applicant): Gastrointestinal (GI) bacteria sense diverse environmental signals, including host hormones and nutrients, as cues for differential gene regulation and niche adaptation. Although the impact of carbon nutrition on the colonization of the gut by the microbiota has been extensively studied, the extent to which carbon sources affect the regulation of virulence factors by invading pathogens has not been fully defined. The PI has shown that the enteric pathogen enterohemorrhagic Escherichia coli (EHEC) gages sugar sources as an important cue to regulate expression of its virulence genes. Specifically, this sugar dependent regulation fine tunes the expression of the locus of enterocyte effacement (LEE) pathogenicity island necessary for the formation of attaching and effacing (AE) lesions on enterocytes. Glycolytic environments inhibit the expression of the LEE genes. Conversely, growth within a gluconeogenic environment activates expression of these genes. Part of this sugar-dependent regulation is achieved through two transcription factors: KdpE and Cra. Cra and KdpE interact to optimally directly activate expression of the LEE genes in a metabolite dependent fashion. This sugar dependent regulation is key during infection of the mammalian host, given that a kdpE mutant is attenuated in vivo. Additionally, a novel two component system, named FusKR (where FusK is a membrane bound histidine sensor kinase (HK), and FusR a response regulator (RR)) that senses fucose, controls expression of the LEE genes. This fucose-sensing system is required for robust EHEC intestinal colonization. During growth in mucus, the glycophagic prominent member of the GI microbiota, Bacteroides thetaiotaomicron, supplies fucose to EHEC, modulating its virulence gene expression. However, several questions remain answered, such as how does the interplay among the KdpE, Cra and FusR transcription factors controls optimal expression of the LEE genes? It is also known that FusK senses fucose, but an extensive investigation on whether this sensor is responsive to other sugar sources is lacking. Additionally, it is unknown whether FusK exclusively phosphorylates its cognate RR FusR, or whether it can also phosphorylate other non-cognate RRs. Finally, the implications of these complex sugar sensing interactions during mammalian infection, although clearly important due to the attenuation of kdpE and fusR mutants in vivo, remains to be addressed. Hence, the Specific Aims of this grant are: Aim 1: Unravel the mechanistic interactions among KdpE, Cra and FusR on LEE gene expression. Aim 2: Investigate the FusK phosphorelay signaling cascade. Aim 3: Sugar regulation of virulence during mammalian infection.

描述（由申请人提供）：胃肠道（GI）细菌感知不同的环境信号，包括宿主激素和营养物质，作为差异基因调控和生态位适应的线索。尽管碳营养对微生物群在肠道定植的影响已被广泛研究，但碳源影响入侵病原体毒力因子调节的程度尚未完全确定。 PI 表明，肠道病原体肠出血性大肠杆菌 (EHEC) 将糖源作为调节其毒力基因表达的重要线索。具体来说，这种糖依赖性调节微调肠细胞消失（LEE）致病岛基因座的表达，这是肠细胞上形成附着和消失（AE）损伤所必需的。糖酵解环境抑制 LEE 基因的表达。相反，糖异生环境中的生长激活这些基因的表达。这种糖依赖性调节的一部分是通过两个转录因子实现的：KdpE 和 Cra。 Cra 和 KdpE 相互作用，以代谢物依赖性方式最佳地直接激活 LEE 基因的表达。鉴于 kdpE 突变体在体内减弱，这种糖依赖性调节是哺乳动物宿主感染期间的关键。此外，一种名为 FusKR 的新型双组分系统（其中 FusK 是一种膜结合组氨酸传感器激酶 (HK)，FusR 是一种反应调节剂 (RR)），可感应岩藻糖，控制 LEE 基因的表达。这种岩藻糖传感系统是肠出血性大肠杆菌肠道强健定植所必需的。在粘液中生长期间，胃肠道微生物群中的食糖重要成员，多形拟杆菌向肠出血性大肠杆菌提供岩藻糖，调节其毒力基因表达。然而，仍有几个问题需要解答，例如 KdpE、Cra 和 FusR 转录因子之间的相互作用如何控制 LEE 基因的最佳表达？众所周知，FusK 可以感应岩藻糖，但目前还缺乏对该传感器是否对其他糖源有反应的广泛研究。此外，尚不清楚 FusK 是否专门磷酸化其同源 RR FusR，或者是否也可以磷酸化其他非同源 RR。最后，尽管由于体内 kdpE 和 fusR 突变体的减弱，这些复杂的糖感应相互作用在哺乳动物感染过程中的影响显然很重要，但仍有待解决。因此，该资助的具体目标是： 目标 1：揭示 KdpE、Cra 和 FusR 之间对 LEE 基因表达的机制相互作用。目标 2：研究 FusK 磷酸中继信号级联。目标 3：哺乳动物感染期间毒力的糖调节。