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，可引起多种肠道和肠外疾病。EHEC从动物到人的主要传播途径之一是通过食物摄取生的或未煮熟的食物。不同的环境(食物)和宿主(人类胃肠道)营养供应可能会在EHEC中诱导特定的代谢和毒力相关调节。然而，这些机制在很大程度上是不被描述的。在这个项目中，我们将研究EHEC菌株对宿主和环境特定生长条件的差异蛋白质组和代谢反应，例如与食物相关的生长介质、模拟回肠(SIEM)和结肠(SCEM)、好氧/厌氧生长条件和水分活度。将分析EHEC的基本代谢系统(如碳营养)如何对特定环境做出反应，以及这如何与致病性和毒力因子的表达联系起来。对促进感染第一步的决定因素(例如菌毛的表达、膜运输系统、转移到厌氧呼吸)的调控将是我们工作的重点。EHEC菌株在特定环境和宿主生长条件下的蛋白质组的定性和定量差异分析将在荧光二维凝胶电泳法(2-DGE)分离后进行。代谢途径，即碳代谢，将通过使用(U-13C6)葡萄糖的同位素图谱进行研究。差异表达的蛋白质组和代谢组对EHEC致病性的影响将主要在肠道细胞培养模型和体外器官培养(IVOC)项目的后期阶段建立。这些实验有助于更好地了解EHEC在肠道中的生存和竞争机制，以及代谢系统对EHEC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.