Bafilomycin A1 inhibits <em>Helicobacter pylori</em>-induced vacuolization of HeLa cells.

Bafilomycin A1, a specific inhibitor of the vacuolar-type H⁺-ATPase, responsible for acidification of intracellular compartments, prevents the vacuolization of Hela cells induced by H. pylori, with an inhibitory concentration giving 50% of maximal (ID₅₀) 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. [ABSTRACT FROM AUTHOR]