Membrane-bound ATPase of a Psychrophilic Marine Bacterium,Vibriosp. Strain ABE-1

Abstract

Several properties of ATPase bound to the inner membrane of a psychrophilic marine bacterium Vibrio sp. strain ABE-1 were examined. The membrane-bound ATPase had two optimal peaks of the activity at pH 5.8 and 7.3. The ATPase activity was strongly inhibited by N,N’- dicyclohexylcarbodiimide (DCCD) and NaN3 at pH 5.8 and 8.0, and stimulated by MgCl2 and CaCl2 at pH 8.0. At pH 8.0, the enzyme hydrolyzed GTP and ITP as well as ATP but not AMP or p-nitrophenylphosphate. CTP, UTP, and ADP were poor substrates. These characteristics indicate that there is a F0F1-type ATPase in the inner membrane of this bacterium. In addition, the ATPase activity was also significantly inhibited by Na3 Vo4, suggesting the coexistence of a P-type ATPase as a minor constituent. The membrane-bound ATPase activity was maximum at 50°C, but the strong DCCD-sensitivity observed at 20°C was greatly reduced at this temperature.