PDF(Pubmed)
Abstract：
In Escherichia coli, the disaccharide trehalose can be metabolized as a carbon source or be accumulated as an osmoprotectant under osmotic stress. In hypertonic environments, E. coli accumulates trehalose in the cell by synthesis from glucose mediated by the cytosolic enzymes OtsA and OtsB. Trehalose in the periplasm can be hydrolyzed into glucose by the periplasmic trehalase TreA. We have previously shown that a treA mutant of extraintestinal E. coli strain BEN2908 displayed increased resistance to osmotic stress by 0.6 M urea, and reduced production of type 1 fimbriae, reduced invasion of avian fibroblasts, and decreased bladder colonization in a murine model of urinary tract infection. Since loss of TreA likely results in higher periplasmic trehalose concentrations, we wondered if deletion of otsA and otsB genes, which would lead to decreased internal trehalose concentrations, would reduce resistance to stress by 0.6 M urea and promote type 1 fimbriae production. The BEN2908ΔotsBA mutant was sensitive to osmotic stress by urea, but displayed an even more pronounced reduction in production of type 1 fimbriae, with the consequent reduction in adhesion/invasion of avian fibroblasts and reduced bladder colonization in the murine urinary tract. The BEN2908ΔtreAotsBA mutant also showed a reduction in production of type 1 fimbriae, but in contrast to the ΔotsBA mutant, resisted better than the wild type in the presence of urea. We hypothesize that, in BEN2908, resistance to stress by urea would depend on the levels of periplasmic trehalose, but type 1 fimbriae production would be influenced by the levels of cytosolic trehalose.
摘要：
在大肠杆菌中，二糖海藻糖可以作为碳源代谢或在渗透胁迫下作为渗透保护剂积累。在高渗环境中，大肠杆菌通过由胞质酶OtsA和OtsB介导的葡萄糖合成在细胞中积累海藻糖。周质海藻糖酶TreA可以将周质中的海藻糖水解为葡萄糖。我们先前已经表明，肠外大肠杆菌菌株BEN2908的treA突变体显示出0.6M尿素对渗透胁迫的抗性增加，减少了1型菌毛的产量，减少禽成纤维细胞的侵袭，在小鼠尿路感染模型中膀胱定植减少。由于TreA的丢失可能导致更高的周质海藻糖浓度，我们想知道是否缺失了otsA和otsB基因，这将导致内部海藻糖浓度降低，会降低0.6M尿素对胁迫的抵抗力，并促进1型菌毛的产生。BEN2908ΔotsBA突变体对尿素的渗透胁迫敏感，但是显示出1型菌毛的产量更明显的减少，从而减少禽类成纤维细胞的粘附/侵袭，并减少小鼠泌尿道中的膀胱定植。BEN2908ΔtreAotsBA突变体还显示出1型菌毛的产量减少，但是与ΔotsBA突变体相反，在尿素存在下的抗性比野生型更好。我们假设，在BEN2908中，尿素对应激的抗性将取决于周质海藻糖的水平，但是1型菌毛的产生会受到胞浆海藻糖水平的影响。
