title: Structure of the c(10) ring of the yeast mitochondrial ATP synthase in the open conformation.
abstract: The proton pore of the F(1)F(o) ATP synthase consists of a ring of c subunits, which rotates, driven by downhill proton diffusion across the membrane. An essential carboxylate side chain in each subunit provides a proton-binding site. In all the structures of c-rings reported to date, these sites are in a closed, ion-locked state. Structures are here presented of the c(10) ring from Saccharomyces cerevisiae determined at pH 8.3, 6.1 and 5.5, at resolutions of 2.0 Å, 2.5 Å and 2.0 Å, respectively. The overall structure of this mitochondrial c-ring is similar to known homologs, except that the essential carboxylate, Glu59, adopts an open extended conformation. Molecular dynamics simulations reveal that opening of the essential carboxylate is a consequence of the amphiphilic nature of the crystallization buffer. We propose that this new structure represents the functionally open form of the c subunit, which facilitates proton loading and release.
authors.affiliation: Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, The Chicago Medical School, Chicago, Illinois, USA.
authors.forename: Jindrich
authors.initials: J
authors.lastname: Symersky
authors.forename: Vijayakanth
authors.initials: V
authors.lastname: Pagadala
authors.forename: Daniel
authors.initials: D
authors.lastname: Osowski
authors.forename: Alexander
authors.initials: A
authors.lastname: Krah
authors.forename: Thomas
authors.initials: T
authors.lastname: Meier
authors.forename: José D
authors.initials: JD
authors.lastname: Faraldo-Gómez
authors.forename: David M
authors.initials: DM
authors.lastname: Mueller
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D025261:Mitochondrial Proton-Translocating ATPases / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry; D011522:Protons; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000201:enzymology*
chemical_list: D021122:Protein Subunits; D011522:Protons; C474451:F1F0-ATP synthase; D025261:Mitochondrial Proton-Translocating ATPases