IS ATP SYNTHESIZED BY A VACUOLAR-ATPASE IN THE EXTREMELY HALOPHILIC BACTERIA

The proton-dependent synthesis of ATP was demonstrated in representati ve members of the genera Halobacterium, Haloarcula, and Haloferax. In all cases, synthesis was not inhibited by nitrate or N-ethylmaleimide, inhibitors of the vacuolar-like ATPases found in Archaea, but was aff ected by azide, an inhibitor of F0F1-ATP synthases. These observations extend the earlier observations with Halobacterium saccharovorum and suggest that ATP synthesis in these organisms is brought about by an F 0F1-ATP synthase.