Transcriptional regulation from the cell surface: conformational changes in the transmembrane protein FecR lead to altered transcription of the ferric citrate transport genes in Escherichia coli

Ferric citrate induces the ferric citrate transport system in Escherichia coli without being taken up into cells. The cytoplasmic transmembrane protein FecR, required for the response to ferric citrate, was found to be cleaved by a cellular protease. FecR protein produced by fecR mutants impaired or constitutive in fecA transcription was protease resistant, indicating that conformational changes affect proper functioning of FecR.