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A sodium ion‐dependent A 1 A O ATP synthase from the hyperthermophilic archaeon Pyrococcus furiosus
Author(s) -
Pisa Kim Y.,
Huber Harald,
Thomm Michael,
Müller Volker
Publication year - 2007
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2007.05925.x
Subject(s) - pyrococcus furiosus , atp synthase , atp hydrolysis , atpase , chemistry , pyrococcus horikoshii , enzyme , crystallography , sodium , membrane , atp synthase gamma subunit , ion , protein subunit , hydrolysis , biochemistry , biophysics , biology , archaea , organic chemistry , gene
The rotor subunit c of the A 1 A O 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 K m of 0.6 m m . 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 ′‐dicyclohexylcarbodiimide could be relieved by Na + . Taken together, these data demonstrate the use of Na + as coupling ion for the A 1 A O ATP synthase of Pyrococcus furiosus , the first Na + A 1 A O ATP synthase described.