THE ATP SYNTHASE OF STREPTOMYCES-LIVIDANS - CHARACTERIZATION AND PURIFICATION OF THE F1FO COMPLEX

Everted membrane vesicles of the Gram-positive eubacterium Streptomyce s lividans were prepared and the ATP synthase (F1F0) was characterized in its membrane-bound form. In addition, the F1F0 complex was solubil ized, purified, and functionally reconstituted into phospholipid vesic les. The enzyme complex is similar with respect to subunit composition to those of other eubacterial ATP synthases. Whereas the F-1 part onl y exhibits ATPase activity in the presence of CaCl2 (Hensel, M., Decke rs-Hebestreit, G. and Altendorf, K. (1991) fur. J. Biochem. 202, 1313- 1319), the membrane-bound ATPase is also moderately stimulated by high concentrations of Mg2+ ions (20 mM). In contrast, the physiological f unctions of the ATP synthase, i.e., ATP-driven H+ translocation and AT P synthesis are strictly dependent on Mg2+ ions. The biochemical prope rties of the ATP synthase of S. lividans show distinct similarity to t he enzyme complex of rhodobacteria and bacilli. The ATPase activity is inhibited by N,N'-dicyclohexylcarbodiimide, venturicidin, and tributy ltin, typical inhibitors of F1F0-ATPases, which react with the membran e-bound F-0 complex. In addition, the ATPase activity is highly sensit ive towards oligomycin, a feature which is only shared by the ATP synt hase of rhodobacteria and mitochondria.