The structure of cbb3 cytochrome oxidase provides insights into proton pumping.
The heme-copper oxidases (HCOs) accomplish the key event of aerobic respiration; they couple O2 reduction and transmembrane proton pumping. To gain new insights into the still enigmatic process, we structurally characterized a C-family HCO--essential for the pathogenicity of many bacteria--that differs from the two other HCO families, A and B, that have been structurally analyzed. The x-ray structure of the C-family cbb3 oxidase from Pseudomonas stutzeri at 3.2 angstrom resolution shows an electron supply system different from families A and B. Like family-B HCOs, C HCOs have only one pathway, which conducts protons via an alternative tyrosine-histidine cross-link. Structural differences around hemes b and b3 suggest a different redox-driven proton-pumping mechanism and provide clues to explain the higher activity of family-C HCOs at low oxygen concentrations.
Buschmann
Sabine
S
Max-Planck-Institut für Biophysik, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany.
Warkentin
Eberhard
E
Xie
Hao
H
Langer
Julian D
JD
Ermler
Ulrich
U
Michel
Hartmut
H
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000378:metabolism; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism*; D006418:Heme / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D019897:Periplasm / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017494:Proton Pumps / Q000737:chemistry* / Q000378:metabolism*; D011522:Protons; D044223:Pseudomonas stutzeri / Q000201:enzymology*; D014443:Tyrosine / Q000737:chemistry
D017494:Proton Pumps; D011522:Protons; D014443:Tyrosine; D006418:Heme; D006639:Histidine; C414443:cbb3 oxidase; D003576:Electron Transport Complex IV; D010100:Oxygen