Cytochrome bd Displays Significant Quinol Peroxidase Activity.
Cytochrome bd is a prokaryotic terminal oxidase that catalyses the electrogenic reduction of oxygen to water using ubiquinol as electron donor. Cytochrome bd is a tri-haem integral membrane enzyme carrying a low-spin haem b558, and two high-spin haems: b595 and d. Here we show that besides its oxidase activity, cytochrome bd from Escherichia coli is a genuine quinol peroxidase (QPO) that reduces hydrogen peroxide to water. The highly active and pure enzyme preparation used in this study did not display the catalase activity recently reported for E. coli cytochrome bd. To our knowledge, cytochrome bd is the first membrane-bound quinol peroxidase detected in E. coli. The observation that cytochrome bd is a quinol peroxidase, can provide a biochemical basis for its role in detoxification of hydrogen peroxide and may explain the frequent findings reported in the literature that indicate increased sensitivity to hydrogen peroxide and decreased virulence in mutants that lack the enzyme.
Department of Biotechnology, Delft University of Technology, The Netherlands.
Sinan
S
Al-Attar
Department of Biotechnology, Delft University of Technology, The Netherlands.
Yuanjie
Y
Yu
Department of Biotechnology, Delft University of Technology, The Netherlands.
Martijn
M
Pinkse
Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr 21, 79014 Freiburg i. Br., Germany.
Jo
J
Hoeser
Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr 21, 79014 Freiburg i. Br., Germany.
Thorsten
T
Friedrich
Department of Molecular Cell Biology, AIMMS, Faculty of Earth- and Life Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
Dirk
D
Bald
Department of Biotechnology, Delft University of Technology, The Netherlands.
Simon
S
de Vries
D003573:Cytochrome b Group; D003580:Cytochromes / Q000737:chemistry / Q000378:metabolism*; D045222:Electron Transport Chain Complex Proteins / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D006873:Hydroquinones / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
D003573:Cytochrome b Group; D003580:Cytochromes; D045222:Electron Transport Chain Complex Proteins; D029968:Escherichia coli Proteins; D006873:Hydroquinones; D010088:Oxidoreductases; C040077:cytochrome bd terminal oxidase complex, E coli