Nitrogen fixation by aerobic prokaryotes appears paradoxical: the nitrogen-fixing enzymes—nitrogenases—are notoriously oxygen-labile, yet many bacteria fix nitrogen aerobically. This review summarises the evidence that cytochrome bd, a terminal oxidase unrelated to the mitochondrial and many other bacterial oxidases, plays a crucial role in aerotolerant nitrogen fixation in Azotobacter vinelandii and other bacteria by rapidly consuming oxygen during uncoupled respiration. We review the pertinent properties of this oxidase, particularly its complement of redox centres, the catalytic cycle of oxygen reduction, the affinity of the oxidase for oxygen, and the regulation of cytochrome bd gene expression. The roles of other oxidases and other mechanisms for limiting damage to nitrogenase are assessed.
Review Article| June 01 1997
Respiratory Protection of Nitrogenase Activity in Azotobacter vinelandii—Roles of the Terminal Oxidases
Robert K. Poole;
Robert K. Poole
1Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN
2Nitrogen Fixation Laboratory, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
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Biosci Rep (1997) 17 (3): 303–317.
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Robert K. Poole, Susan Hill; Respiratory Protection of Nitrogenase Activity in Azotobacter vinelandii—Roles of the Terminal Oxidases. Biosci Rep 1 June 1997; 17 (3): 303–317. doi: https://doi.org/10.1023/A:1027336712748
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