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Figure 4
Mutagenesis of the FhuE substrate-binding site reveals residues that are key for receptor function and selectivity. (a) A cross-eyed stereo representation of the FhuE substrate-binding site containing Fe-coprogen. Residues involved in coprogen coordination that were subjected to mutagenesis are shown as blue sticks, coprogen is shown as a red wire and Fe is shown as an orange sphere. Interactions between FhuE and coprogen of <3.5 Å are labelled. (b) The effect of mutations of FhuE on its ability to utilize the siderophores as an iron source to support the growth of E. coli ΔTBDT on solid agar. Growth differences were scored by observing the size of growth around a spot of siderophore compared with that of wild-type FhuE. The growth of the N373A mutant with ferrioxamine B as a substrate is highlighted; using this substrate, the growth of the N373A mutant exceeded that of wild-type FhuE.

IUCrJ
Volume 6| Part 3| May 2019| Pages 401-411
ISSN: 2052-2525
https://doi.org/10.1107/S2052252519002926