5. Conclusion

Pi homeostasis is essential for life's basic processes. Without the ability to control intracellular levels of Pi within optimal levels, cells would be unable to maintain energy stores, synthesize nucleic acids and phospholipids, or carry out central metabolic pathways. The molecular mechanisms by which E. coli cells maintain intracellular Pi levels include utilizing multiple importers with characteristic patterns of expression, affinities for Pi and rates of Pi import [4]. These cells also employ a highly characterized signal transduction system that monitors extracellular Pi levels through the conformational states of the high-affinity Pi importer to control gene expression for scavenging Pi and utilizing alternate phosphorous sources. In addition, polyphosphate plays an important role in fine-tuning the amounts of free intracellular Pi. Understanding these mechanisms is important because this knowledge can be used to design organisms and pathways for the remediation of phosphate pollution. Moreover, the expression of virulence genes in many organisms is controlled by the PhoBR signal transduction system.
