Fig. 2

Complex structure of PfeA with Fe³⁺- enterobactin. a F_O–F_C electron density omit map at 3 σ around Fe³⁺-enterobactin complex. Enterobactin is shown as sticks with carbon atoms coloured in blue, nitrogen in dark blue and oxygen in red. The Fe³⁺ is represented as an orange sphere. b Fe³⁺-enterobactin binds to the extracellular loops. The N-terminal plug domain is coloured in blue, the β-barrel in yellow and the NL1 and NL3 loops in orange. Secondary structure elements involved in the binding site have been labelled. c Binding site of the siderophore. Residues within 4.0 Å of the siderophore are displayed and hydrogen bonds are shown as black broken lines. d Comparison of the apo (green) and complex (yellow) structures. Loops NL1, L4, and L11 which undergo a large change of conformation have been highlighted in magenta