MetaCyc Enzyme: ferredoxin--nitrite reductase

Gene: nirA Accession Number: SYNPCC7942_1240 (MetaCyc)

Species: Synechococcus elongatus PCC 7942

The gene encoding nitrite reductase from the cyanobacterium Synechococcus elongatus PCC 7942 has been identified and sequenced [Luque93]. This gene encodes a polypeptide that shows similarity to nitrite reductase from higher plants and to the sulfite reductase hemoprotein from enteric bacteria.

Identities with the above-mentioned proteins were found in the region that holds an Fe4S4-siroheme active center, suggesting that nitrite reductase from Synechococcus bears an active site similar to that present in those reductases.

In a mutant that was defficient in nitrate transport, growth on low amounts of nitrate resulted in a five-fold increase in the transcription of nirA [Suzuki96].

Addition of ammonium abolished the accumulation of the transcript, indicating that ammonium is an inhibitor of transcription. L-glutamine, the immediate product of ammonium fixation, also showed negative effect on the transcription of cbbL, encoding the large subunbit of RubisCO. In addition, the glutamine metabolites cyanate and carbamoyl-phosphate were shown to repress transcription of nirA [Johnson].

Map Position: [1,263,263 <- 1,264,801]

Molecular Weight of Polypeptide: 56.541 kD (from nucleotide sequence)

Unification Links: Entrez-gene:3773528 , InterPro:IPR006066 , NCBI Entrez Protein (GI):81168930 , Protein Model Portal:P39661 , String:1140.Synpcc7942_1240 , UniProt:P39661

Relationship Links: InterPro:IN-FAMILY:IPR005117 , InterPro:IN-FAMILY:IPR006066 , InterPro:IN-FAMILY:IPR006067 , InterPro:IN-FAMILY:IPR012798 , Pfam:IN-FAMILY:PF01077 , Pfam:IN-FAMILY:PF03460 , Prints:IN-FAMILY:PR00397 , Prosite:IN-FAMILY:PS00365

Gene-Reaction Schematic: ?

Gene-Reaction Schematic


Created 01-May-2008 by Caspi R , SRI International

Enzymatic reaction of: ferredoxin--nitrite reductase

EC Number:

ammonium + 6 an oxidized ferredoxin + 2 H2O <=> nitrite + 6 a reduced ferredoxin + 8 H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the opposite direction.

In Pathways: nitrate reduction VI (assimilatory)

Cofactors or Prosthetic Groups: siroheme [Luque93]

Inhibitors (Other): cyanate [Johnson] , carbamoyl-phosphate [Johnson]

Primary Physiological Regulators of Enzyme Activity: cyanate , carbamoyl-phosphate


Johnson: Johnson AK, Schwob JE "Cephalic angiotensin receptors mediating drinking to systemic angiotensin II." Pharmacol Biochem Behav 3(6);1077-84. PMID: 177996

Luque93: Luque I, Flores E, Herrero A (1993). "Nitrite reductase gene from Synechococcus sp. PCC 7942: homology between cyanobacterial and higher-plant nitrite reductases." Plant Mol Biol 21(6);1201-5. PMID: 8490140

Suzuki96: Suzuki I, Sugiyami T, Omata T (1996). "Regulation by cyanate of the genes involved in carbon and nitrogen assimilation in the cyanobacterium Synechococcus sp. strain PCC 7942." J Bacteriol 178(9);2688-94. PMID: 8626339

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Fri Oct 9, 2015, biocyc11.