Matthies, Doreen; Zhou, Wenchang; Klyszejko, Adriana L.; Anselmi, Claudio; Yildiz, Oezkan; Brandt, Karsten; Mueller, Volker; Faraldo-Goemez, Jose D.; Meier, Thomas
High-resolution structure and mechanism of an F/V-hybrid rotor ring in a Na+-coupled ATP synthase
NATURE COMMUNICATIONS, 5 Art. No. 5286, NOV 2014

All rotary ATPases catalyse the interconversion of ATP and ADP-P-i 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 angstrom 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.

DOI:10.1038/ncomms6286

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