Iron-sulphur (FeS) clusters are important cofactors for numerous proteins involved in electron transfer, in redox and non-redox catalysis, in gene regulation, and as sensors of oxygen and iron. These functions depend on the various FeS cluster prosthetic groups, the most common being [2Fe-2S] and [4Fe-4S] [ PUBMED:16221578 … expand

Iron-sulphur (FeS) clusters are important cofactors for numerous proteins involved in electron transfer, in redox and non-redox catalysis, in gene regulation, and as sensors of oxygen and iron. These functions depend on the various FeS cluster prosthetic groups, the most common being [2Fe-2S] and [4Fe-4S] [ PUBMED:16221578 ]. FeS cluster assembly is a complex process involving the mobilisation of Fe and S atoms from storage sources, their assembly into [Fe-S] form, their transport to specific cellular locations, and their transfer to recipient apoproteins. So far, three FeS assembly machineries have been identified, which are capable of synthesising all types of [Fe-S] clusters: ISC (iron-sulphur cluster), SUF (sulphur assimilation), and NIF (nitrogen fixation) systems.

In the NIF system, NifS and NifU are required for the formation of metalloclusters of nitrogenase in Azotobacter vinelandii, and other organisms, as well as in the maturation of other FeS proteins. Nitrogenase catalyses the fixation of nitrogen. It contains a complex cluster, the FeMo cofactor, which contains molybdenum, Fe and S. NifS is a cysteine desulphurase. NifU binds one Fe atom at its N-terminal, assembling an FeS cluster that is transferred to nitrogenase apoproteins [ PUBMED:11498000 ]. Nif proteins involved in the formation of FeS clusters can also be found in organisms that do not fix nitrogen [ PUBMED:8875867 ].

This domain is found at the N terminus of NifU (from NIF system) and NifU related proteins, and in the human Nfu protein. Both of these proteins are thought to be involved in the assembly of iron-sulphur clusters, functioning as scaffolds [ PUBMED:12886008 PUBMED:14993221 ].