Fig. 4. Exogenous (Glc)Ent compete with (Glc)Ent–Amp conjugates for FepA and IroN recognition. (a)–(c) Growth of E. coli CFT073 in the presence of 100 nM (Glc)Ent–Amp 5/7/9 and mixtures of 100 nM (Glc)Ent–Amp 5/7/9 and 1, 5, 20, or 100 equiv of exogenous (a) Ent 1, (b) MGE 2, or (c) DGE 3 in the presence of 200 μM DP. (d)–(f) Growth of E. coli UTI89 in the presence of 100 nM (Glc)Ent–Amp 5/7/9 and mixtures of 100 nM (Glc)Ent–Amp 5/7/9 and 1, 5, 20, or 100 equiv of exogenous (d) Ent 1, (e) MGE 2, or (f) DGE 3 in the presence of 200 μM DP. All assays were performed in 50% MHB medium (t = 19 h, T = 30 °C) (mean ± standard deviation, n = 3). An asterisk indicates OD₆₀₀ < 0.01. The data for (Glc)Ent–Amx 6/8/10 are presented in Fig. S15.† .