Periplasmic nitrate reductase, large subunit (IPR010051)

Short name: Periplasm_NO3_reductase_lsu

Overlapping homologous superfamilies


Family relationships



This entry represents the large subunit of a family of nitrate reductases found in proteobacteria which are localised to the periplasm. This subunit binds molybdopterin and contains a twin-arginine motif at the N terminus. The protein associates with NapB, a soluble haem-containing protein and NapC, a membrane-bound cytochrome c. The periplasmic nitrate reductases are not involved in the assimilation of nitrogen, and are not directly involved in the formation of electrochemical gradients (i.e. respiration) either. Rather, the purpose of this enzyme is either dissimilatory (i.e. to dispose of excess reductive equivalents) or indirectly respiratory by virtue of the consumption of electrons derived from NADH via the proton translocating NADH dehydrogenase. The enzymes from Ralstonia eutropha (Alcaligenes eutrophus) [PMID: 8376334] and Paracoccus pantotrophus (Thiosphaera pantotropha) [PMID: 7639719] have been characterised. In Escherichia coli [PMID: 11844760] (as well as other organisms) this gene is part of a large nitrate reduction operon (napFDAGHBC).

GO terms

Biological Process

GO:0055114 oxidation-reduction process

Molecular Function

GO:0030151 molybdenum ion binding
GO:0008940 nitrate reductase activity

Cellular Component

GO:0042597 periplasmic space

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.