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Gene Review

blr2715  -  oxidase

Bradyrhizobium diazoefficiens USDA 110

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Disease relevance of blr2715


High impact information on blr2715

  • The tlpA mutant had a pleiotropic phenotype in that it was defective in the development of a nitrogen fixing endosymbiosis and exhibited a strongly decreased oxidase activity, as compared with the wild-type [5].
  • Holocytochrome aa3 was spectroscopically undetectable in the mutant, whereas the apoprotein of subunit one (CoxA) of this oxidase was still synthesized and incorporated into the cytoplasmic membrane [5].
  • Furthermore, fixN insertion and fixNO deletion mutants grown microaerobically or anaerobically (with nitrate) exhibited a strong decrease in whole-cell oxidase activity as compared with the wild type [1].
  • To analyze the contribution of these 12 invariant histidines of FixN in cofactor binding and function of the Bradyrhizobium japonicum cbb3-type oxidase, they were substituted by valine or alanine by site-directed mutagenesis [6].
  • All mutants, except the fixQ mutant, showed clearly altered absorption difference spectra of their membranes and decreased oxidase activities, and they were unable to fix nitrogen symbiotically [7].

Chemical compound and disease context of blr2715


Biological context of blr2715

  • The Bradyrhizobium japonicum cbb3-type cytochrome oxidase, which supports microaerobic respiration, is a multisubunit enzyme encoded by the genes of the fixNOQP operon [7].
  • The possible oxidase biogenesis pathway involves the formation of a primary core complex consisting of FixN and FixO, which allows the subsequent association with FixP to form the complete enzyme [7].
  • This 20K cytochrome c appeared to catalyse electron transport from the cytochrome bc1 complex to the aa3-type terminal oxidase and, unlike mitochondrial cytochrome c, was membrane-bound in B. japonicum [11].
  • Mutant analysis also showed that this oxidase has no influence on photosynthetic growth and nitrogen-fixation activity [2].
  • In this paper, we describe the cloning and sequencing of the coxX gene encoding the large catalytic subunit for a fourth terminal oxidase from B. japonicum [4].

Associations of blr2715 with chemical compounds

  • It has been a long-standing hypothesis that the endosymbiotic rhizobia (bacteroids) cope with a concentration of 10 to 20 nM free O2 in legume root nodules by the use of a specialized respiratory electron transport chain terminating with an oxidase that ought to have a high affinity for O2 [12].
  • The purified oxidase has TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine) oxidase activity as well as cytochrome c oxidase activity [12].
  • The oxidase complex was not able to oxidize a ubiquinol homolog possessing a single isoprenoid unit side chain [13].
  • Enzymological studies confirmed presence of Thiosulphate oxidase, sulphite oxidase and Rhodanese, all of which play role in sulfur metabolism pathway [14].

Other interactions of blr2715

  • A B. japonicum cycM insertion mutant (COX122) exhibited an oxidase-negative phenotype and apparently lacked cytochrome aa3 in addition to the CycM protein [15].
  • However, the S. meliloti ccdA mutant also lacked cytochrome oxidase aa(3), a defect that does not appear to have been reported for other bacteria [16].
  • A role for the flavoprotein as a terminal oxidase was implicated based on its high redox potential and its sensitivity to cyanide [17].

Analytical, diagnostic and therapeutic context of blr2715

  • Western blot analyses showed that an intact heme binding site in the FixO polypeptide is a prerequisite not only for the synthesis of holo-FixO protein but also for the formation of the entire cbb3-type oxidase complex [18].
  • Terminal oxidase cyanide inhibition titration pattern comparisons of the wild type with a coxWXYZ insertion mutant indicated the new oxidase is expressed microaerobically [19].


  1. Genes for a microaerobically induced oxidase complex in Bradyrhizobium japonicum are essential for a nitrogen-fixing endosymbiosis. Preisig, O., Anthamatten, D., Hennecke, H. Proc. Natl. Acad. Sci. U.S.A. (1993) [Pubmed]
  2. The ccoNOQP gene cluster codes for a cb-type cytochrome oxidase that functions in aerobic respiration of Rhodobacter capsulatus. Thöny-Meyer, L., Beck, C., Preisig, O., Hennecke, H. Mol. Microbiol. (1994) [Pubmed]
  3. Functional analysis of the fixNOQP region of Azorhizobium caulinodans. Mandon, K., Kaminski, P.A., Elmerich, C. J. Bacteriol. (1994) [Pubmed]
  4. Genetic evidence for a fourth terminal oxidase in Bradyrhizobium japonicum. Surpin, M.A., Moshiri, F., Murphy, A.M., Maier, R.J. Gene (1994) [Pubmed]
  5. Bradyrhizobium japonicum TlpA, a novel membrane-anchored thioredoxin-like protein involved in the biogenesis of cytochrome aa3 and development of symbiosis. Loferer, H., Bott, M., Hennecke, H. EMBO J. (1993) [Pubmed]
  6. How replacements of the 12 conserved histidines of subunit I affect assembly, cofactor binding, and enzymatic activity of the Bradyrhizobium japonicum cbb3-type oxidase. Zufferey, R., Arslan, E., Thöny-Meyer, L., Hennecke, H. J. Biol. Chem. (1998) [Pubmed]
  7. Assembly and function of the cytochrome cbb3 oxidase subunits in Bradyrhizobium japonicum. Zufferey, R., Preisig, O., Hennecke, H., Thöny-Meyer, L. J. Biol. Chem. (1996) [Pubmed]
  8. Cytochrome aa3 gene regulation in members of the family Rhizobiaceae: comparison of copper and oxygen effects in Bradyrhizobium japonicum and Rhizobium tropici. Gabel, C., Bittinger, M.A., Maier, R.J. Appl. Environ. Microbiol. (1994) [Pubmed]
  9. Histidine 131, not histidine 43, of the Bradyrhizobium japonicum FixN protein is exposed towards the periplasm and essential for the function of the cbb3-type cytochrome oxidase. Zufferey, R., Thöny-Meyer, L., Hennecke, H. FEBS Lett. (1996) [Pubmed]
  10. Genetic evidence for 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) as a negative effector of cytochrome terminal oxidase cbb3 production in Rhizobium etli. Soberón, M., Lopez, O., Miranda, J., Tabche, M.L., Morera, C. Mol. Gen. Genet. (1997) [Pubmed]
  11. Genetic analysis of the cytochrome c-aa3 branch of the Bradyrhizobium japonicum respiratory chain. Bott, M., Bolliger, M., Hennecke, H. Mol. Microbiol. (1990) [Pubmed]
  12. A high-affinity cbb3-type cytochrome oxidase terminates the symbiosis-specific respiratory chain of Bradyrhizobium japonicum. Preisig, O., Zufferey, R., Thöny-Meyer, L., Appleby, C.A., Hennecke, H. J. Bacteriol. (1996) [Pubmed]
  13. Purification and characterization of an O2-utilizing cytochrome-c oxidase complex from Bradyrhizobium japonicum bacteroid membranes. Keefe, R.G., Maier, R.J. Biochim. Biophys. Acta (1993) [Pubmed]
  14. Molecular dissection of diheme cytochrome C gene from soil isolate of a gram negative, facultative chemolithotrophic sulfur oxidizer. Banerjee, I., Nagee, A., Mukhopadhyaya, P.N., Kothari, I.L. Roumanian archives of microbiology and immunology (2004) [Pubmed]
  15. The Bradyrhizobium japonicum cycM gene encodes a membrane-anchored homolog of mitochondrial cytochrome c. Bott, M., Ritz, D., Hennecke, H. J. Bacteriol. (1991) [Pubmed]
  16. Pleiotropic effects of mutations that alter the Sinorhizobium meliloti cytochrome c respiratory system. Yurgel, S.N., Berrocal, J., Wilson, C., Kahn, M.L. Microbiology (Reading, Engl.) (2007) [Pubmed]
  17. Involvement of cytochromes and a flavoprotein in hydrogen oxidation in Rhizobium japonicum bacteroids. O'Brian, M.R., Maier, R.J. J. Bacteriol. (1983) [Pubmed]
  18. Heme C incorporation into the c-type cytochromes FixO and FixP is essential for assembly of the Bradyrhizobium japonicum cbb3-type oxidase. Zufferey, R., Hennecke, H., Thöny-Meyer, L. FEBS Lett. (1997) [Pubmed]
  19. The Bradyrhizobium japonicum coxWXYZ gene cluster encodes a bb3-type ubiquinol oxidase. Surpin, M.A., Lübben, M., Maier, R.J. Gene (1996) [Pubmed]
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