Staphylococcus aureus adenosine triphosphatase: inhibitor sensitivity and release from membrane

Abstract

Homogeneous preparations of cytoplasmic membrane isolated from S. aureus 6538P exhibited membrane-associated ATPase activity. Membrane ATPase activity was activated by divalent cations (4.0 mM: Mg2+ > Mn2+ > Co2+ > Zn2+), and ATP was hydrolyzed more readily than other nucleoside triphosphates and phosphorylated substrates. The pH optimum for the membrane ATPase was 6.5. The ATPase could not be released from the membrane by differential osmotic treatments, but detergent treatment effectively solubilized active enzyme. The nonionic detergent Triton X-100 (1%) released a protein with ATPase activity, after substrate-dependent staining in polyacrylamide gels, that differed slightly in electrophoretic migration when compared to the active enzyme solubilized with sodium dodecyl sulfate (0.1%). Membrane-associated ATPase activity was inhibited by N,N''-dicyclohexylcarbodiimide (0.001-1 mM) and NaF (50% inhibition at 5 mM NaF). Azide and trypsin inhibited activity; ouabain had a slight inhibitory effect. Diethylstilbestrol showed appreciable activation of the membrane ATPase over the range employed (0.001-1 mM).