Nitrogenase iron protein NifH (IPR005977)

Short name: Nitrogenase_Fe_NifH

Overlapping homologous superfamilies

Family relationships


The enzyme responsible for nitrogen fixation, the nitrogenase, shows a high degree of conservation of structure, function, and amino acid sequence across wide phylogenetic ranges. All known Mo-nitrogenases consist of two components, component I (also called dinitrogenase, or Fe-Mo protein), an alpha2beta2 tetramer encoded by the nifD and nifK genes, and component II (dinitrogenase reductase, or Fe protein) a homodimer encoded by the nifH gene [PMID: 10903367, PMID: 12823187] which has an Fe4S4 cluster bound between the subunits and two ATP-binding domains. The Fe protein supplies energy by ATP hydrolysis, and transfers electrons from reduced ferredoxin or flavodoxin to component 1 for the reduction of molecular nitrogen to ammonia [PMID: 11913144, PMID: 8286368]. Nitrogenase contains two unusual rare metal clusters; one of them is the iron molybdenum cofactor (FeMo-co), which is considered to be the site of dinitrogen reduction and whose biosynthesis requires the products of the nifNE operon and of some other nif genes [PMID: 8226614]. It has been proposed that nifNE might serve as a scaffold upon which FeMo-co is built and then inserted into component I [PMID: 7876209].

This entry represents the nitrogenase iron protein (component II), which is encoded by nifH.

GO terms

Biological Process

GO:0009399 nitrogen fixation
GO:0055114 oxidation-reduction process

Molecular Function

GO:0016163 nitrogenase activity

Cellular Component

GO:0016612 molybdenum-iron nitrogenase complex

Contributing signatures

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