Structural changes linked to proton translocation by subunit c of the ATP synthase

F1F0 ATP synthases use a transmembrane proton gradient to drive the synthesis of cellular ATP. The structure of the cytosolic F-1 portion of the enzyme and the basic mechanism of ATP hydrolysis by F-1 are now well established, but how proton translocation through the transmembrane F-0 portion drives these catalytic changes is less clear. Here we describe the structural changes in the proton-translocating F-0 subunit c that are induced by deprotonating the specific aspartic acid involved in proton transport. conformational changes between the protonated and deprotonated forms of subunit c provide the structural basis for an explicit mechanism to explain coupling of proton translocation by F-0 to the rotation of subunits within the core of F-1. Rotation of these subunits within F-1 causes the catalytic conformational changes in the active sites of F-1 that result in ATP synthesis.