Electrogenic Na+ transport by Enterococcus hirae Na+-ATPase

AbstractEnergy-dependent generation of a membrane potential (Δψ) (−45 mV, interior negative) was observed in the F0F1, H+-ATPase-defective mutant of Enterococcus hirae. The generation of Δψ was found at high pH (but not at low pH), for which intracellular Na+ was required but not extracellular K+. The Δψ-generating activity was induced in cells cultured in media containing high concentrations of Na+, and was not observed in the Na+-ATPase mutants. These results suggest that E. hirae Na+-ATPase is responsible for the electrogenic sodium pump