THE ALPHA-BETA-COMPLEXES OF ATP SYNTHASE - THE ALPHA-3-BETA-3 OLIGOMER AND ALPHA-1-BETA-1 PROTOMER

The basic structures of the catalytic portion (F1, alpha3beta3gammadeltaepsilon of ATP synthase are the alpha3beta3 hexamer (oligomer with cooperativity) and alpha1beta1 heterodimer (protomer). These were reconstituted from the alpha and beta subunits of thermophilic F1 (TF1), and the alpha3beta3 hexamer was crystallized. On electrophoresis, both the dimer and hexamer showed bands with ATPase activity. Using the dimer and hexamer, we studied the nucleotide-dependent rapid molecular dynamics. The formation of the hexamer required neither nucleotide nor Mg. The hexamer was dissociated into the dimer in the presence of MgADP, while the dimer was associated into the hexamer in the presence of MgATP. The hexamer, like mitochondrial F1 and TF1, showed two kinds of ATPase activity: one was cooperative and was inhibited by only one BzADP per hexamer. and the other was inhibited by three BzADP per hexamer.