Sugar Regulation of EHEC virulence

肠出血性大肠杆菌毒力的糖调节

• 批准号: 9099669
• 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 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9099669
• 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; Health; 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; microbiota; mutant; novel; nutrition; pathogen; 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）细菌感知到不同的环境信号，包括宿主激素和营养，作为差异基因调控和利基适应性的线索。尽管碳营养对微生物群对肠道的殖民化的影响已经进行了广泛的研究，但碳源通过入侵病原体影响毒力因子的调节程度尚未得到充分定义。 PI表明，肠道病原体肠肠肠肠球菌大肠杆菌（EHEC）将糖源作为调节其毒力基因表达的重要提示。具体而言，这种糖依赖的调节微调了肠肠细胞脱落（LEE）致病岛的表达，这是在肠上皮细胞上形成和卵形（AE）病变所必需的。糖酵解环境抑制了Lee基因的表达。相反，葡萄糖生成环境中的生长激活了这些基因的表达。通过两个转录因子来实现这种糖依赖性调节的一部分：KDPE和CRA。 CRA和KDPE相互作用以最佳的方式直接以代谢物依赖性方式激活Lee基因的表达。鉴于kDPE突变体在体内减弱，这种依赖性糖调节是感染哺乳动物宿主感染期间的关键。此外，一种新型的两个组件系统，称为FUSKR（其中Fusk是一种膜结合的组氨酸传感器激酶（HK）和FUSR A响应调节剂（RR））控制fucose，可控制fucose，控制Lee基因的表达。这种岩藻糖感应系统是强大的EHEC肠道定植所必需的。在粘液中生长的过程中，gi微生物群的血糖著名成员，菌触thetaiotaomicron，向EHEC提供了Fucose，从而调节其毒力基因的表达。但是，仍然有几个问题的回答，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感应了岩藻糖，但是对该传感器是否对其他糖源的反应进行了广泛的研究。另外，未知Fusk是否仅将其同源RR FUSR磷酸化，还是还可以磷酸化其他非同名RR。最后，在哺乳动物感染过程中，这些复杂的糖传感相互作用的含义显然很重要，这是由于体内KDPE和FUSR突变体的衰减，但仍有待解决。因此，该赠款的具体目的是：目标1：揭示KDPE，CRA和FUSR对Lee基因表达的机械相互作用。 AIM 2：研究Fusk Phosphoray信号传导级联。目标3：哺乳动物感染期间毒力的糖调节。