Redox-dependent conformational changes in cytochrome C oxidase suggest a gating mechanism for proton uptake.

ABSTRACT: A role for conformational change in the coupling mechanism of cytochrome c oxidase is the subject of controversy. Relatively small conformational changes have been reported in comparisons of reduced and oxidized crystal structures of bovine oxidase but none in bacterial oxidases. Comparing the X-ray crystal structures of the reduced (at 2.15 A resolution) and oxidized forms of cytochrome c oxidase from Rhodobacter sphaeroides, we observe a displacement of heme a(3) involving both the porphyrin ring and the hydroxyl farnesyl tail, accompanied by protein movements in nearby regions, including the mid part of helix VIII of subunit I which harbors key residues of the K proton uptake path, K362 and T359. The conformational changes in the reduced form are reversible upon reoxidation. They result

SUBMITTER: Qin L 

PROVIDER: S-EPMC2720787 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature