5.B.10 The VciB Ferric Iron Reductase (VciB) Family
VciB catalyzes the reduction of Fe3+ to Fe2+ which can be subsequently transported into the cell with the ferrous iron transporter, Feo (Peng and Payne 2017). Iron reduction is independent of functional iron transport, but is associated with the electron transport chain. Comparative analysis of VciB orthologs (e.g., those from Burkholderia and Aeromonas species) suggested a similar role for other proteins in the VciB family. VciB is a dimer located in the inner membrane with three transmembrane segments and a large periplasmic loop. Directed mutagenesis of the protein revealed that two highly-conserved histidine residues are required for function (Peng and Payne 2017). The results support a model whereby VciB reduces ferric iron using energy from the electron transport chain.