Structure of the mitochondrial ATP synthase by electron cryomicroscopy

We have determined the structure of intact ATP synthase from bovine heart mitochondria by electron cryomicroscopy of single particles. Docking of an atomic model of the F-1-c(10) subcomplex into a major segment of the map has allowed the 32 Angstrom resolution density to be interpreted as the F-1-ATPase, a central and a peripheral stalk and an F-O membrane region that is composed of two domains. One domain of F-O corresponds to the ring of c-subunits, and the other probably contains the a-subunit, the transmembrane portion of the b-subunit and the remaining integral membrane proteins of F-O. The peripheral stalk wraps around the molecule and connects the apex of F-1 to the second domain of F-O. The interaction of the peripheral stalk with F-1-c(10) implies that it binds to a non-catalytic alpha-beta interface in F-1 and its inclination where it is not attached to F-1 suggests that it has a flexible region that can serve as a stator during both ATP synthesis and ATP hydrolysis.