SUBUNIT STRUCTURE AND ORGANIZATION OF THE GENES OF THE A(1)A(0) ATPASE FROM THE ARCHAEON METHANOSARCINA-MAZEI GO1

The proton-translocating A(1)A(0) ATP synthase/hydrolase of Methanosar cina mazei Go1 was purified and shown to consist of six subunits of mo lecular masses of 65, 49, 40, 36, 25, and 7 kDa. Electron microscopy r evealed that this enzyme is organized in two domains, the hydrophilic A(1) and the hydrophobic A(0) domain, which are connected by a stalk. Genes coding for seven hydrophilic subunits were cloned and sequenced. From these data it is evident that the 65-, 49-, 40- and 25-kDa subun its are encoded by ahaA, ahaB, ahaC, and ahaD, respectively; they are part of the A, domain or the stalk. In addition there are three more g enes, ahaE, ahaF, and ahaG, encoding hydrophilic subunits, which were apparently lost during the purification of the protein. The A(0) domai n consists of at least the 7-kDa proteolipid and the 36 kDa subunit fo r which the genes have not yet been found. In summary, it is proposed that the A(1)A(0) ATPase of Methanosarcina mazei Go1 contains at least nine subunits, of which seven are located in A(1) and/or the stalk an d two in A(0).