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

点击翻译按钮获取中文摘要

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.