We have cloned and sequenced the genes for the subunits of the proton-translocating ATP synthase of Bacillus megaterium QM B1551. The arrangement of the genes is identical to the arrangement of the same genes (the unc operon) in Escherichia coli. The genes for the Fo subunits immediately precede the genes for the F1 subunits and are themselves preceded by an open reading frame which codes for a protein similar to the E. coli i protein. In contrast to the E. coli ATPase genes, the transcript for these ATPase genes does not include this open reading frame.