Plays an essential role in iron intracellular trafficking to iron cofactor biogenesis systems including iron-sulfur cluster (Fe-S) or heme assembly (PubMed:21744456, PubMed:25826316). Promotes the biosynthesis of iron-sulfur clusters by delivering Fe to the complex composed of the cysteine desulfurase SufS and the zinc-dependent sulfurtransferase SufU (PubMed:27382962). Also plays a critical role in coproporphyrin-dependent heme b biogenesis and thus provides an essential function for the bacterial global metabolism. Binds 1.0 Fe(2+) (PubMed:20087498) to 1.5 to 3.2 Fe(2+) per monomer (PubMed:21744456). Homodimer, upon Fe(2+) binding (PubMed:20087498). Interacts with the SufS/SufU complex (PubMed:27382962). Interacts with CpfC (PubMed:25826316). Reduced growth in rich medium, unable to grow in minimal medium. Reduced activity of Fe-S-dependent aconitase (citB). Reactive oxygen species are drastically reduced. No bacillibactin (BB), an endogenous siderophore, produced. 20% higher intracellular iron concentrations. Extended N-terminus.