ATP synthases: bioinformatic based insights into how their electrochemically driven motor comprised of subunits a and c might serve as a drug target

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 H⁺ transport, the surrounding residues differ among species. Such divergence could lead to different regulatory modes since pH-dependent H⁺ transport has been demonstrated in E. 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 which is determined by the higher ordered structure. Recently, it was 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.