Ferric citrate transport system (Fec system)

The ferric citrate transport system (Fec system) is a multi-component, membrane-associated transporter complex found in Gram-negative bacteria (most notably E. coli) that mediates the uptake of iron in the form of ferric-citrate. It consists of an outer membrane TonB-dependent transporter (FecA), a periplasmic binding protein (FecB), inner membrane permease proteins (FecC/FecD), and a cytoplasmic ATPase (FecE). The system is tightly regulated by FecR, an inner membrane signal transducer, and FecI, a sigma factor controlling operon expression. The Fec system is essential for bacterial survival in iron-limited environments, is induced by ferric-citrate, and is a potential target for antibacterial strategies that disrupt bacterial iron acquisition. In summary, "Membrane-associated iron/citrate transport sites" refers most directly to the ferric citrate transport system (Fec system) found in bacteria, whose canonical molecular targets are well-defined proteins such as FecA, FecB, and associated ABC transporters, rather than a single receptor or transporter. The generic phrase is not the preferred canonical name for molecular targeting.

Other names

Fec systemFerric citrate uptake systemFecA (outer membrane transporter)FecB (periplasmic binding protein)FecC/FecD (membrane permease)FecE (ATPase)FecR (regulator)FecI (sigma factor)

Transport inhibition: Blocking the binding or translocation of ferric-citrate (e.g., iron chelators competitively inhibit the uptake of iron-citrate complexes) TonB/FecA disruption: Small molecules or antibodies interfering with TonB or FecA function inhibit energy transduction or substrate uptake