Iron-regulated synthesis and uptake of colicin V

Abstract Virulent strains of Escherichia coli frequently contain ColV plasmids. It is shown that synthesis of the marker protein, colicin V, is regulated by iron via the iron repressor encoded by the fur gene. Mutants in the Cir outer membrane protein, in tonB , as well as in the exbB gene are resistant to colicin V suggesting all three functions to be required for colicin V uptake.