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Báo cáo khoa học: A sodium ion-dependent A1AO ATP synthase from the hyperthermophilic archaeon Pyrococcus furiosus

The rotor subunitc of the A1AOATP synthase of the hyperthermophilic archaeon Pyrococcus furiosuscontains a conserved Na + -binding motif, indicating that Na + is a coupling ion. To experimentally address the nat-ure of the coupling ion, we isolated the enzyme by detergent solubilization from native membranes followed by chromatographic separation tech-niques. | ễFEBS Journal A sodium ion-dependent A1AO ATP synthase from the hyperthermophilic archaeon Pyrococcus furiosus Kim Y. Pisa1 Harald Huber2 Michael Thomm2 and Volker Muller1 1 Molecular Microbiology Bioenergetics Institute of Molecular Biosciences Johann Wolfgang Goethe Universitat Frankfurt Germany 2 Lehrstuhl fur Mikrobiologie Universitat Regensburg Germany Keywords A1AO ATP synthase Archaea hyperthermophile Na Pyrococcus Correspondence V. Muller Molecular Microbiology Bioenergetics Institute of Molecular Biosciences Johann Wolfgang Goethe Universitat Frankfurt Max-von-Laue-Str. 9 60438 Frankfurt Germany Fax 49 69 79829306 Tel 49 69 79829507 E-mail vmueller@bio.uni-frankfurt.de Received 30 April2007 revised 5 June 2007 accepted 8 June 2007 doi 10.1111 j.1742-4658.2007.05925.x The rotor subunit c of the AlAo ATP synthase of the hyperthermophilic archaeon Pyrococcus furiosus contains a conserved Na -binding motif indicating that Na is a coupling ion. To experimentally address the nature of the coupling ion we isolated the enzyme by detergent solubilization from native membranes followed by chromatographic separation techniques. The entire membrane-embedded motor domain was present in the preparation. The rotor subunit c was found to form an SDS-resistant oligomer. Under the conditions tested the enzyme had maximal activity at 100 C had a rather broad pH optimum between pH 5.5 and 8.0 and was inhibited by diethystilbestrol and derivatives thereof. ATP hydrolysis was strictly dependent on Na with a Km of 0.6 mM. Li but not K could substitute for Na . The Na dependence was less pronounced at higher proton concentrations indicating competition between Na and H for a common binding site. Moreover inhibition of the ATPase by N .N -di-cyclohexylcarbodiimide could be relieved by Na . Taken together these data demonstrate the use of Na as coupling ion for the A1Ao ATP synthase of Pyrococcus furiosus the first Na A1AO ATP synthase described. Membrane-bound multisubunit .