title: The X-ray crystal structures of wild-type and EQ(I-286) mutant cytochrome c oxidases from Rhodobacter sphaeroides.
abstract: The structure of cytochrome c oxidase from Rhodobacter sphaeroides has been solved at 2.3/2.8A (anisotropic resolution). This high-resolution structure revealed atomic details of a bacterial terminal oxidase including water molecule positions and a potential oxygen pathway, which has not been reported in other oxidase structures. A comparative study of the wild-type and the EQ(I-286) mutant enzyme revealed structural rearrangements around E(I-286) that could be crucial for proton transfer in this enzyme. In the structure of the mutant enzyme, EQ(I-286), which cannot transfer protons during oxygen reduction, the side-chain of Q(I-286) does not have the hydrogen bond to the carbonyl oxygen of M(I-107) that is seen in the wild-type structure. Furthermore, the Q(I-286) mutant has a different arrangement of water molecules and residues in the vicinity of the Q side-chain. These differences between the structures could reflect conformational changes that take place upon deprotonation of E(I-286) during turnover of the wild-type enzyme, which could be part of the proton-pumping machinery of the enzyme.
authors.affiliation: Department of Biochemistry, Biomedical Center, Uppsala University, Box 576, Uppsala, Sweden. margareta.e.ek@astrazeneca.com
authors.forename: Margareta
authors.initials: M
authors.lastname: Svensson-Ek
authors.forename: Jeff
authors.initials: J
authors.lastname: Abramson
authors.forename: Gisela
authors.initials: G
authors.lastname: Larsson
authors.forename: Susanna
authors.initials: S
authors.lastname: Törnroth
authors.forename: Peter
authors.initials: P
authors.lastname: Brzezinski
authors.forename: So
authors.initials: S
authors.lastname: Iwata
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D003300:Copper / Q000378:metabolism; D018360:Crystallography, X-Ray; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D006860:Hydrogen Bonding; D008024:Ligands; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D011487:Protein Conformation; D021122:Protein Subunits; D011522:Protons; D012242:Rhodobacter sphaeroides / Q000201:enzymology* / Q000235:genetics; D014867:Water / Q000378:metabolism; D014978:Xenon / Q000378:metabolism
chemical_list: D008024:Ligands; D021122:Protein Subunits; D011522:Protons; D014867:Water; D014978:Xenon; D003300:Copper; D003576:Electron Transport Complex IV; D010100:Oxygen