Involved in iron-sulfur cluster biogenesis. Binds a 4Fe-4S cluster, can transfer this cluster to apoproteins, and thereby intervenes in the maturation of Fe/S proteins. Could also act as a scaffold/chaperone for damaged Fe/S proteins. Binds 1 [4Fe-4S] cluster per subunit. The cluster is presumably bound at the interface of two monomers. Homodimer. Belongs to the NfuA family.