Persson Orjan, Valadi Asa, Nyström Thomas, Farewell Anne
Department of Cell and Molecular Biology-Microbiology, Göteborg University, Box 462, 405 30 Göteborg, Sweden.
Mol Microbiol. 2007 Aug;65(4):968-78. doi: 10.1111/j.1365-2958.2007.05838.x. Epub 2007 Jul 19.
The universal stress protein (Usp) superfamily encompasses a conserved group of proteins involved in stress resistance, adaptation to energy deficiency, cell motility and adhesion, and is found in all kingdoms of life. The paradigm usp gene, uspA, of Escherichia coli is transcriptionally activated by a large variety of stresses, and the alarmone ppGpp is required for this activation. Here, we show that the uspA gene is also regulated by an intermediate of the glycolytic/gluconeogenic pathways. Specifically, mutations and conditions resulting in fructose-6-phosphate (F-6-P) accumulation elicit superinduction of uspA upon carbon starvation, whereas genetic manipulations reducing the pool size of F-6-P have the opposite effect. This metabolic control of uspA does not act via ppGpp. Other, but not all, usp genes of the usp superfamily are similarly affected by alterations in F-6-P levels. We suggest that alterations in the pool size of phosphorylated sugars of the upper glycolytic pathway may ensure accumulation of required survival proteins preceding the complete depletion of the external carbon source. Indeed, we show that uspA is, in fact, induced before the carbon source is depleted from the medium.
通用应激蛋白（Usp）超家族包含一组保守的蛋白质，这些蛋白质参与抗逆性、对能量缺乏的适应、细胞运动和黏附，并且存在于所有生命王国中。大肠杆菌的典型usp基因uspA在多种应激条件下被转录激活，并且警报素ppGpp是这种激活所必需的。在这里，我们表明uspA基因也受糖酵解/糖异生途径的一种中间产物调控。具体而言，导致6-磷酸果糖（F-6-P）积累的突变和条件会在碳饥饿时引发uspA的超诱导，而降低F-6-P库大小的基因操作则有相反的效果。uspA的这种代谢调控不通过ppGpp起作用。usp超家族的其他（但并非全部）usp基因也受到F-6-P水平变化的类似影响。我们认为，糖酵解上游途径中磷酸化糖的库大小变化可能确保在外部碳源完全耗尽之前积累所需的生存蛋白。事实上，我们表明uspA实际上是在培养基中的碳源耗尽之前被诱导的。
