Ferric citrate outer membrane transporter (FecA)

Ferric citrate outer membrane transporter (FecA) is an outer membrane protein found in Gram-negative bacteria such as *Escherichia coli*. FecA acts as both a transporter and a signal transducer: it selectively binds ferric citrate complexes at the cell surface and, via a TonB-dependent mechanism, actively imports iron into the periplasmic space[1][2][3][7]. The transported iron is crucial for bacterial survival and virulence, especially in iron-limited environments such as the mammalian host[1][2][7]. Concurrent with transport function, FecA also transduces a regulatory signal across the membrane, leading to induction of the fecABCDE operon for iron uptake components[1][3][5]. FecA's structure comprises a β-barrel with plug and globular domains responsible for ligand recognition, uptake, and signal initiation[1][4][6][7]. The FecA system is a classic model of TonB-dependent transmembrane importers and is crucial for bacterial adaptation to iron-restricted ecological niches.

Other names

Fe(3+) dicitrate transport protein FecAIron(III) dicitrate transport protein FecAfecA

Facilitates the high-affinity uptake of ferric citrate complexes through the outer membrane by binding substrate extracellularly, transmitting a conformational signal via TonB interactions, and activating inward translocation coupled to signal transduction for gene activation[1][2][3][7].