Sodium. Its Role in Bacterial Metabolism
This chapter reviews the multiple roles of the sodium ion Na+ in the physiology of bacteria. Virtually all cells need to extrude Na+ in order to maintain a constant internal environment. In many bacteria, transport of Na+ out of the cell has an important additional role in harnessing energy and distributing it within the cell. In these cases, Na+ takes on the role otherwise played by H+ in chemiosmotic energetic functions. As a means of exploring these functions, we will examine a subset of Na+ transport enzymes that are prototypical of the various catalytic processes involved in Na+ homeostasis and Na+ chemiosmosis.