A conserved steroid binding site in cytochrome C oxidase.
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.
Qin
Ling
L
Biochemistry and Molecular Biology Department, Michigan State University, East Lansing, Michigan 48824, USA.
Mills
Denise A
DA
Buhrow
Leann
L
Hiser
Carrie
C
Ferguson-Miller
Shelagh
S