The colicin G, H and X determinants encode microcins M and H47, which might utilize the catecholate siderophore receptors FepA, Cir, Fiu and IroN.
Patzer SI, Baquero MR, Bravo D, Moreno F, Hantke K. Microbiology (Reading). 2003 Sep; 149(Pt 9):2557-2570.