MOLECULAR-CLONING OF GENES ENCODING MAJOR 2 SUBUNITS OF A EUBACTERIAL V-TYPE ATPASE FROM THERMUS-THERMOPHILUS

The atpAB genes which encode the alpha and beta-subunits of membrane ATPase from a thermophilic eubacterium, Thermus thermophilus HB8, were cloned. The deduced amino-acid sequences of the alpha-subunit (583 amino acids) and the beta-subunit (478 amino acids) are only moderately similar to the alpha and beta-subunits of the F0F1-ATPases, while they are highly similar to the major two subunits of the V-type ATPases, a family of ATPases which have been so far found in eukaryotic endomembrane vacuolar vesicles and archaebacterial plasma membranes. Thus, T. thermophilus ATPase belongs to the V-type ATPase family, even though this bacterium is a eubacterium. The hypothesis that the differentiation of an ancestral ATPase into V-type and F0F1-ATPase occurred after the evolution of a primordial cell into archaebacteria and eubacteria should be modified accordingly.