Figure 2

Diagram showing best BLAST hit relationships between ATP synthases, subunit A (Figure 2A) and subunit B (Figure 2B) for two bacteria, Escherichia coli and Bacillus subtilis , and two archaea, Methanosarcina mazei and Sulfolobus solfataricus. Some confusion prevails in the annotation of ATP synthase subunits for bacteria and archaea: the beta chain in bacteria is the catalytic subunit and corresponds to subunit A in archaeal and eukaryotic vacuolar type ATPases; the alpha chain, or non-catalytic subunit, in bacteria corresponds to subunit B in archaea [46]. In addition, the archaeal A subunit is sometimes labelled as alpha subunit. To simplify our discussion and the diagrammatic representation we designate all catalytic subunits, either from bacteria or from archaea as ATP-A, and all non-catalytic subunits as ATP-B.