Novel features in the structure of bovine ATP synthase

The F1F0-ATP synthase from bovine heart mitochondria catalyses the synthesi s of ATP from ADP and inorganic phosphate by using the energy of an electro chemical proton gradient derived from electron transport. The enzyme consis ts of three major domains: the globular F-1 catalytic domain of known atomi c structure lies outside the lipid bilayer and is attached by a central sta lk to the intrinsic membrane domain, F-0, which transports protons through the membrane. Proton transport through F-0 evokes structural changes that a re probably transmitted by rotation of the stalk to the catalytic sites in F-1. In an alpha(3)beta(3)gamma(1) subcomplex, the rotation of the central gamma subunit driven by ATP hydrolysis has been visualised by optical micro scopy. Ln order to prevent the alpha(3)beta(3) structure from following the rotation of the central gamma subunit, it has been proposed that the enzym e might have a stator connecting static parts in F-0 to alpha(3)beta(3), th ereby keeping it fixed relative to the rotating parts. Here we present elec tron microscopy images that reveal three new features in bovine F1F0-ATPase , one of which could be a stator. The second feature is a collar structure above the membrane domain and the third feature is some additional density on top of the F-1 domain. (C) 1999 Academic Press.