title: Crystal structure of bovine mitochondrial factor B at 0.96-A resolution.
abstract: Coupling factor B (FB) is a mitochondrial inner membrane polypeptide that facilitates the energy-driven catalysis of ATP synthesis in animal mitochondria by blocking a proton leak across the membrane. Here, we report the crystal structure of the bovine mitochondrial FB mutant with Gly-3-Glu substitution determined at a resolution of 0.96 A and that of the WT polypeptide at a resolution of 2.9 A. The structure reveals an oblong, oval-shaped molecule with a unique globular N-terminal domain that is proposed to be the membrane anchor domain and the capping region to the C-terminal leucine-rich repeats domain. A short N-terminal alpha-helix, which extends away from the molecule's body, is suggestive of functioning as an anchor for FB to the matrix side of the mitochondrial inner membrane. Identification of a bound Mg(2+) ion reveals that FB is a metalloprotein. We also report the cocrystal structures of FB bound with phenylarsine oxide and Cd(2+), two known inhibitors of the FB coupling activity.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158-2517, USA.
authors.forename: John K
authors.initials: JK
authors.lastname: Lee
authors.forename: Grigory I
authors.initials: GI
authors.lastname: Belogrudov
authors.forename: Robert M
authors.initials: RM
authors.lastname: Stroud