The noncatalytic site-deficient alpha(3)beta(3)gamma subcomplex and F0F1-ATP synthase can continuously catalyse ATP hydrolysis when P-i is present

We investigated ATP hydrolysis by a mutant (Delta NC) alpha(3)beta(3)gamma subcomplex of F0F1-ATP synthase from the thermophilic Bacillus PS3 that is defective in the noncatalytic nucleotide binding sites. This mutant subcomp lex was activated by inorganic phosphate ions (P-i) and did not show contin uous ATP hydrolysis activity in the absence of P-i. P-i also activated the wild-type alpha(3)beta(3)gamma subcomplex in a similar manner. Sulphate act ivated wild-type alpha(3)beta(3)gamma but not Delta NC alpha(3)beta(3)gamma , indicating that P-i activation did not involve noncatalytic sites but tha t sulphate activation did. P-i also activated ATP hydrolysis and coupled pr oton translocation by the wild-type and Delta NC F0F1-ATP synthases reconst ituted into vesicle membranes.