MetaCyc Enzyme: nitric oxide reductase

Species: Pseudomonas stutzeri

Subunit composition of nitric oxide reductase = [NorB][NorC]
         nitric oxide reductase large subunit = NorB (summary available)
         nitric-oxide reductase small subunit = NorC (summary available)

Nitric oxide reductase is an integral membrane component of the anaerobic respiratory chain of Pseudomonas stutzeri, which results in denitrification. The enzyme catalyzes the reduction of nitric oxide to nitrous oxide, a reaction that involves the formation of an N-N bond, in essence a reversal of nitrogen fixation. NO reduction is coupled to electron transport phosphorylation [Zumft94, Heiss89, Braun91, Kastrau94, Zumft97, Watmough99].

The enzyme consists of a cytochrome c and cytochrome b subunits [Kastrau94], encoded by the norC and norB, respectively. The two genes are contiguous and transcribed as a single 2.0-kb transcript [Zumft94].

The cytochrome b subunit is highly hydrophobic. Purified enzyme contained a cardiolipin, an L-1-phosphatidyl-glycerol, and an L-1-phosphatidylethanolamine, the latter being the major component. An activity of 60 μmol nitric oxide/min/mg protein was obtained after electrophoresis in the presence of laurylpropanediol-3-phosphorylcholine ether [Kastrau94]

The cytochrome c subunit is membrane-anchored, while the cytochrome b subunit has 12 transmembrane regions [Philippot02]. Spectroelectrochemical oxidoreductive titrations gave E'o (versus standard hydrogen electrode) of +322 mV for the cytochrome b and +280 mV for the cytochrome c components [Kastrau94].

Locations: periplasm

Molecular Weight: 45.0 kD (experimental) [Kastrau94]

Gene-Reaction Schematic

Gene-Reaction Schematic

GO Terms:
Cellular Component:
GO:0030288 - outer membrane-bounded periplasmic space []

Created 13-Jan-2000 by Pellegrini-Toole A, Marine Biological Laboratory
Revised 15-Oct-2007 by Caspi R, SRI International

Enzymatic reaction of: nitric oxide reductase

Inferred from experiment

Synonyms: NO reductase, nitrous oxide:(acceptor) oxidoreductase (NO-forming)

EC Number:

Transport reaction diagram for nitric oxide reductase

In Pathways: nitrate reduction I (denitrification)

Inhibitors (Unknown Mechanism): free fatty acids [Kastrau94] Regulators of Unknown Type: an L-1-phosphatidyl-glycerol [Kastrau94], a cardiolipin [Kastrau94]

Subunit of nitric oxide reductase: nitric oxide reductase large subunit

Synonyms: NorB

Gene: norB Accession Number: G-253 (MetaCyc)

Locations: membrane

Molecular Weight: 53.006 kD (from nucleotide sequence)

Molecular Weight: 38.0 kD (experimental) [Kastrau94]

GO Terms:
Cellular Component:
GO:0016020 - membrane []

Unification Links: Protein Model Portal:P98008, UniProt:P98008

Relationship Links: InterPro:IN-FAMILY:IPR000883, InterPro:IN-FAMILY:IPR023615, InterPro:IN-FAMILY:IPR023616, Panther:IN-FAMILY:PTHR10422, Pfam:IN-FAMILY:PF00115, Prosite:IN-FAMILY:PS00077, Prosite:IN-FAMILY:PS50855

This subunit binds a heme b-type cytochrome.

Subunit of nitric oxide reductase: nitric-oxide reductase small subunit

Synonyms: NorC

Gene: norC Accession Number: G-254 (MetaCyc)

Locations: membrane

Molecular Weight: 16.508 kD (from nucleotide sequence)

Molecular Weight: 17.0 kD (experimental) [Kastrau94]

GO Terms:
Cellular Component:
GO:0016020 - membrane []

Unification Links: Protein Model Portal:Q52527, UniProt:Q52527

Relationship Links: InterPro:IN-FAMILY:IPR009056, Pfam:IN-FAMILY:PF00034, Prosite:IN-FAMILY:PS51007

This subunit binds a mono-heme c-type cytochrome.


Braun91: Braun C, Zumft WG (1991). "Marker exchange of the structural genes for nitric oxide reductase blocks the denitrification pathway of Pseudomonas stutzeri at nitric oxide." J Biol Chem 1991;266(34);22785-8. PMID: 1744072

Heiss89: Heiss B, Frunzke K, Zumft WG (1989). "Formation of the N-N bond from nitric oxide by a membrane-bound cytochrome bc complex of nitrate-respiring (denitrifying) Pseudomonas stutzeri." J Bacteriol 1989;171(6);3288-97. PMID: 2542222

Kastrau94: Kastrau DH, Heiss B, Kroneck PM, Zumft WG (1994). "Nitric oxide reductase from Pseudomonas stutzeri, a novel cytochrome bc complex. Phospholipid requirement, electron paramagnetic resonance and redox properties." Eur J Biochem 1994;222(2);293-303. PMID: 8020468

Philippot02: Philippot L (2002). "Denitrifying genes in bacterial and Archaeal genomes." Biochim Biophys Acta 1577(3);355-76. PMID: 12359326

Watmough99: Watmough NJ, Butland G, Cheesman MR, Moir JW, Richardson DJ, Spiro S (1999). "Nitric oxide in bacteria: synthesis and consumption." Biochim Biophys Acta 1999;1411(2-3);456-74. PMID: 10320675

Zumft94: Zumft WG, Braun C, Cuypers H (1994). "Nitric oxide reductase from Pseudomonas stutzeri. Primary structure and gene organization of a novel bacterial cytochrome bc complex." Eur J Biochem 1994;219(1-2);481-90. PMID: 7508388

Zumft97: Zumft WG (1997). "Cell biology and molecular basis of denitrification." Microbiol Mol Biol Rev 61(4);533-616. PMID: 9409151

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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