All rotary ATPases catalyse the interconversion of ATP and ADP-Pi through a mechanism that is coupled to the transmembrane flow of H(+) or Na(+). Physiologically, however, F/A-type enzymes specialize in ATP synthesis driven by downhill ion diffusion, ...
All rotary ATPases catalyse the interconversion of ATP and ADP-Pi through a mechanism that is coupled to the transmembrane flow of H(+) or Na(+). Physiologically, however, F/A-type enzymes specialize in ATP synthesis driven by downhill ion diffusion, while eukaryotic V-type ATPases function as ion pumps. To begin to rationalize the molecular basis for this functional differentiation, we solved the crystal structure of the Na(+)-driven membrane rotor of the Acetobacterium woodii ATP synthase, at 2.1 Å resolution. Unlike known structures, this rotor ring is a 9:1 heteromer of F- and V-type c-subunits and therefore features a hybrid configuration of ion-binding sites along its circumference. Molecular and kinetic simulations are used to dissect the mechanisms of Na(+) recognition and rotation of this c-ring, and to explain the functional implications of the V-type c-subunit. These structural and mechanistic insights indicate an evolutionary path between synthases and pumps involving adaptations in the rotor ring.
Organizational Affiliation:
Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany.,1] Theoretical Molecular Biophysics Section, National Heart, Lung and Blood Institute, National Institutes of Health, Building 5635FL, Suite T-800, Bethesda, Maryland 20892, USA [2] Cluster of Excellence Macromolecular Complexes, Max-von-Laue-Str. 15, 60438 Frankfurt am Main, Germany.,1] Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany [2] Cluster of Excellence Macromolecular Complexes, Max-von-Laue-Str. 15, 60438 Frankfurt am Main, Germany.,Theoretical Molecular Biophysics Section, National Heart, Lung and Blood Institute, National Institutes of Health, Building 5635FL, Suite T-800, Bethesda, Maryland 20892, USA.,Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany.
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