Defined subcomplexes of the A1 ATPase from the archaeon Methanosarcina mazei Go¨1: biochemical properties and redox regulation

The potential A1 ATPase genes ahaA, ahaB, ahaC, ahaD, ahaE, ahaF, and ahaG from the anaerobic archaeon Methanosarcina mazei Go¨1 were overexpressed in Escherichia coli DK8 (pTL2). An A1 complex was purified to apparent homogeneity and shown by Western blot and N-terminal sequence analyses to contain subunits A, B, C, D, and F but to be devoid of subunits E and G. Further removal of subunit C was without effect on ATPase activity. The enzyme was most active at pH 5.2 and required bisulfite and acetate for maximal activity. Kinetic studies confirmed three new inhibitors for A1 ATPases (diethylstilbestrol and its derivatives hexestrol and dienestrol) and identified redox modulation as a new type of regulation of archaeal A1 ATPases. [Copyright &y& Elsevier]