The regulation of metabolic pathways by polyphosphate accumulation and its application to fermentation technology

无机聚磷酸盐（polyP）是由数百个磷酸盐通过高能磷酸酐键连接而成的线性聚合物。由于聚P是由聚P激酶（polyP kinase，PPK）从ATP合成的，因此聚P合成的调节被认为与细胞代谢和能量状态密切相关。以前，我们发现，在大肠杆菌中，phoU突变刺激polyP积累导致参与几种代谢途径的基因表达的变化。在这项研究中，我们分析了聚磷积累和硝酸盐呼吸（NR）之间的关系，这是在由phoU破坏引起的基因表达改变中发现的途径之一。杆菌利用△phoU菌株进行的分析表明，除了Phoregulon之外，PhoU还具有调节NR途径的新的阻遏功能。PPK与TCA循环和NADH产生相关蛋白的相互作用通过PPK的pull-down分析揭示。这些结果表明polyP的合成与中枢代谢途径的调节有直接关系。

Inorganic polyphosphate (polyP) is a linear polymer of hundreds of phosphates linked by high-energy phosphoanhydride bonds. Since polyP is synthesized from ATP by polyP kinase (PPK), the regulation of polyP synthesis is thought to be closely related to the cellular metabolism and the energy status. Previously, we found that polyP accumulation stimulated by phoU mutation in Escherichia coli results in the changes in the expression of the genes involved in the several metabolic pathways. In this study, we analyzed the relationship between polyP accumulation and nitrate respiration (NR), one of the pathways found in the altered gene expression caused by phoU disruption in E. coli. The presence of a novel repression function of PhoU that regulates NR pathway besides Phoregulon was suggested from the analysis using a △phoU strain. The interaction of PPK to the proteins involved in TCA cycle and NADH production was revealed by pull-down analysis using PPK. These results suggest the direct relationship between polyP synthesis and the regulation of central metabolic pathway.