NA+ AS COUPLING ION IN ENERGY TRANSDUCTION IN EXTREMOPHILIC BACTERIA AND ARCHAEA

For microoganisms to live under extreme physical conditions requires i mportant adaptations of the cells. In many organisms the use of Na+ in stead of protons as coupling ion in energy transduction is associated with such adaptation. This review focuses on the enzymes that are resp onsible for the generation and utilization of Na+ gradients in extremo philic microorganisms. Aspects that are dealt with include: bioenerget ics and ion homeostasis in extremophilic Bacteria and Archaea; the mol ecular mechanism of Na+ translocation; and (dis)advantages of Na+ as c oupling ion in energy transduction.