Nitrogenase_nifN_2: A subgroup of the NifN subunit of the NifEN complex: NifN forms an alpha2beta2 tetramer with NifE. NifN and nifE are structurally homologous to nitrogenase MoFe protein beta and alpha subunits respectively. NifEN participates in the synthesis of the iron-molybdenum cofactor (FeMoco) of the MoFe protein. NifB-co (an iron and sulfur containing precursor of the FeMoco) from NifB is transferred to the NifEN complex where it is further processed to FeMoco. The nifEN bound precursor of FeMoco has been identified as a molybdenum-free, iron- and sulfur- containing analog of FeMoco. It has been suggested that this nifEN bound precursor also acts as a cofactor precursor in nitrogenase systems which require a cofactor other than FeMoco: i.e. iron-vanadium cofactor (FeVco) or iron only cofactor (FeFeco). This group also contains the Clostidium fused NifN-NifB protein.
Jiyao W et al.(2023). "The conserved domain database in 2023.",