Bafilomycin A1 inhibits Helicobacter pylori ‐induced vacuolization of HeLa cells

Summary Bafilomycin A1, a specific inhibitor of the vacuolar‐type H + ‐ATPase, responsible for acidification of intra‐cellular compartments, prevents the vacuolization of Hela cells induced by H. pylori , with an inhibitory concentration giving 50% of maximal (ID 50 ) of 4 nM. Bafilomycin A1 is also very efficient in restoring vacuolated cells to a normal appearance. The vacuolating activity of Helicobacter pylori is not inhibited by a series of specific inhibitors of vacuolar H + ‐ATPases. These findings indicate that a transmembrane pH gradient is needed for the formation and growth of vacuoles caused by the bacterium and that this pH gradient is due to the activity of a vacuolar ATPase proton pump of HeLa cells.