title: A conserved steroid binding site in cytochrome C oxidase.
abstract: Micromolar concentrations of the bile salt deoxycholate are shown to rescue the activity of an inactive mutant, E101A, in the K proton pathway of Rhodobacter sphaeroides cytochrome c oxidase. A crystal structure of the wild-type enzyme reveals, as predicted, deoxycholate bound with its carboxyl group at the entrance of the K path. Since cholate is a known potent inhibitor of bovine oxidase and is seen in a similar position in the bovine structure, the crystallographically defined, conserved steroid binding site could reveal a regulatory site for steroids or structurally related molecules that act on the essential K proton path.
authors.affiliation: Biochemistry and Molecular Biology Department, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Qin
authors.forename: Denise A
authors.initials: DA
authors.lastname: Mills
authors.forename: Leann
authors.initials: L
authors.lastname: Buhrow
authors.forename: Carrie
authors.initials: C
authors.lastname: Hiser
authors.forename: Shelagh
authors.initials: S
authors.lastname: Ferguson-Miller