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.
A conserved steroid binding site in cytochrome C oxidase.,Qin L, Mills DA, Buhrow L, Hiser C, Ferguson-Miller S Biochemistry. 2008 Sep 23;47(38):9931-3. Epub 2008 Aug 30. PMID:18759498
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↑ Qin L, Mills DA, Buhrow L, Hiser C, Ferguson-Miller S. A conserved steroid binding site in cytochrome C oxidase. Biochemistry. 2008 Sep 23;47(38):9931-3. Epub 2008 Aug 30. PMID:18759498 doi:10.1021/bi8013483