Inhibition of vacuolar H⁺-ATPases by fusidic acid and suramin

The vacuolar system of eukaryotic cells is energized by a few ATP-driven ion pumps. One of these, the H⁺-ATPase, plays a major role in providing the protonmotive force for several organelles, as well as maintaining the proper pH inside the organelles. Formation of the protonmotive force in organelles isolated from the vacuolar system was inhibited by fusidic acid. The inhibition results from a combination of uncoupling the proton pumping and inhibition of the H⁺-ATPase activity. Suramin is also a potent inhibitor of the H⁺-ATPase from chromaffin granules. A possible connection between these activities and inhibition of HIV infection is pointed out.