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

F1F0 ATP synthases use a transmembrane proton gradient to drive the synthes is of cellular ATP. The structure of the cytosolic F-1 portion of the enzym e 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 cha nges in the proton-translocating F-0 subunit c that are induced by deproton ating the specific aspartic acid involved in proton transport. conformation al changes between the protonated and deprotonated forms of subunit c provi de the structural basis for an explicit mechanism to explain coupling of pr oton 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 conformationa l changes in the active sites of F-1 that result in ATP synthesis.