Structure-function relationships of A-, F- and V-ATPases.

Ion-translocating ATPases, such as the F(1)F(o)-, V(1)V(o)- and archaeal A(1)A(o) enzymes, are essential cellular energy converters which transduce the chemical energy of ATP hydrolysis into transmembrane ionic electrochemical potential differences. Based on subunit composition and primary structures of the subunits, these types of ATPases are related through evolution; however, they differ with respect to function. Recent work has focused on the three-dimensional structural relationships of the major, nucleotide-binding subunits A and B of the A(1)/V(1)-ATPases and the corresponding beta and alpha subunits of the F(1)-ATPase, and the location of the coupling subunits within the stalk that provide the physical linkage between the regions of ATP hydrolysis and ion transduction. This review focuses on the structural homologies and diversities of A(1)-, F(1)- and V(1)-ATPases, in particular on significant differences between the stalk regions of these families of enzymes.