Phosphorylation and phosphate-ATP exchange catalyzed by the ATP synthase isolated from Wolinella succinogenes

The ATP synthase, isolated from Wolinella (formerly Vibrio) succinogenes could be fully incorporated into liposomes without significant cleavage of the enzyme or loss of activity. These proteoliposomes, but not the isolated enzyme, catalyzed phosphate-ATP exchange and the phosphorylation of ADP which was driven by an artificially imposed across the liposomal membrane. Phosphorylation driven by light was catalyzed by proteoliposomes containing also bacteriorhodopsin. The three activities were similarly sensitive to protonophores or dicyclohexylcarbodiimide. This sensitivity was similar to that of the electron-transport-driven phosphorylation catalyzed by bacterial membrane vesicles. With a value of 280 mV to drive phosphorylation the turnover number of the enzyme was in the same order of magnitude as that measured in the electron-transport-driven phosphorylation catalyzed by the bacterial membrane. When the was below 150 mV, the phosphorylation activity of the incorporated enzyme was two orders of magnitude slower, and was about as fast as light-driven phosphorylation or as the exchange reaction.