The sodium ion cycle of extremely alkalophilic bacilli is a simple cycle of secondary porters: an electrogenic sodium ion/proton antiporter that catalyzes accumulation of protons (pH homeostasis) and extrusion of sodium ion, and functions secondary to the proton-pumping respiratory chain; and sodium ion/solute symporters that couple solute accumulation to sodium ion re-entry down its electrochemical gradient. The physiology of the cycle is well-characterized, but the molecular properties of the porters and their regulation are unexplored. This project develops genetic approaches that facilitates a molecular characterization. In addition, the gene encoding the antiporter will be cloned. This action funds a visit of an Israeli scientist to collaborate on the cloning of a gene for a transporter protein in bacteria capable of living at extreme pH levels. This transporter plays an integral role in regulating internal acid levels and controls the organism's ability to adapt to extreme environments.
