Abstract
ATP synthases, widely distributed in bacteria, eukaryotic mitochondria and chloroplasts, are highly conserved multi-subunit complexes. Although the conserved acidic residue in the transmembrane helix of the c subunit functions in proton transport, the surrounding residues differ among species. Such divergence could lead to different regulatory modes since pH-dependent proton transport has been demonstrated in Escherichia coli with a c subunit carrying an additional acidic residue in the helix. There is further divergence in the number of c subunits that form the ring structure in F0. Recently, it was also suggested that certain chemicals recognize the a and c subunits of pathogenic bacterial F0. Since there may be structural divergence even in well-conserved ATP synthases, the c subunit-ring as well as the a subunit in F0 could be targets for drugs for specific bacterial species.
