Double mutagenesis of a positive charge cluster in the ligand-binding site of the ferric enterobactin receptor, FepA

摘要

Siderophores and colicins enter bacterial cells through TonB-dependent outer membrane proteins. Us- ing site-directed substitution mutagenesis, we studied ligand recognition by a prototypic Escherichia coli siderophore re- ceptor, FepA, that binds the iron chelate ferric enterobactin and colicins B and D. These genetic experiments identified a common binding site for two of the three ligands, containing multiple positive charges, within cell surface residues of FepA.