Regulation of Metabolism and Pathogenicity Networks in Enterohemorrhagic Escherichia coli (EHEC)

肠出血性大肠杆菌（EHEC）是食源性感染的严重病原体，可引起广泛的肠道和肠外疾病。肠出血性大肠杆菌从动物到人的主要传播途径之一是通过消化吸收生的或未煮熟的食物。不同的环境（食物）和宿主特异性（人类胃肠道）营养供应可能诱导肠出血性大肠杆菌的特定代谢和毒力相关调控。然而，这些机制在很大程度上是未描述的。在这个项目中，我们将研究肠出血性大肠杆菌菌株对宿主和环境特定生长条件的差异蛋白质组学和代谢反应，如食物相关生长介质、模拟回肠（SIEM）和结肠培养基（SCEM）、好氧/厌氧生长条件和水活性。将分析肠出血性大肠杆菌的基本代谢系统（例如碳营养）如何对特定环境作出反应，以及这如何与致病性和毒力因子的表达联系起来。促进感染第一步的决定因素的调控（例如，菌毛的表达，膜运输系统，向厌氧呼吸的转变）将是我们工作的重点。在荧光二维凝胶电泳（2-DIGE）分离后，将对特定环境和宿主生长条件下的肠出血性大肠杆菌菌株的蛋白质组进行定性和定量差异分析。代谢途径，即碳代谢，将通过使用（U-13C6）葡萄糖的同位素谱分析进行研究。差异表达的蛋白质组和代谢组对肠出血性大肠杆菌致病性的影响将主要在肠细胞培养模型中建立，并在项目的后期通过体外器官培养（IVOC）建立。这些实验有助于更好地了解肠出血性大肠杆菌在肠道中的生存和竞争机制以及代谢系统对肠出血性大肠杆菌致病性的影响。

Enterohemorrhagic Escherichia coli (EHEC) are serious causative agents of food-borne infections and can cause a broad range of intestinal and extraintestinal diseases. One of the major transmission pathways of EHEC from animal to man occurs by the alimentary uptake of raw or undercooked foods. The different environment (food)- and host-specific (human gastrointestinal tract) nutrient supply may induce specific metabolic and virulence-associated regulons in EHEC. However, these mechanisms are largely undescribed. In this project we will investigate the differential proteomic and metabolic responses of EHEC strains to host- and environment-specific growth conditions, such as food-related growth media, simulated ileal (SIEM) and colonic medium (SCEM), aerobic/anaerobic growth conditions, and water activity. It will be analyzed how essential metabolic systems (e.g. carbon nutrition) of EHEC react to specific environments and how this is linked to pathogenicity and the expression of virulence factors. The regulation of determinants that facilitates the first steps of infection (e.g. expression of fimbriae, membrane transport systems, shift to anaerobic respiration) will be in the focus of our work. Qualitative and quantitative differential analysis of the proteome of EHEC strains under particular environmental and host growth conditions will be performed following separation by fluorescence 2-dimensional-gelelectrophoresis (2-DIGE). Metabolic pathways, i.e. carbon metabolism, will be investigated by isotopologue profiling using (U-13C6) glucose. The influence of the differentially expressed proteome and metabolome on EHEC pathogenicity will primarily be established in intestinal cell culture models and in a later phase of the project with in vitro organ cultures (IVOC). These experiments lead to a better understanding of the mechanisms of survival and competition of EHEC in the gut and the influence of the metabolic system to EHEC-pathogenicity.