Thermostable homologues of the periplasmic siderophore-binding protein CeuE from Geobacillus stearothermophilus and Parageobacillus thermoglucosidasius

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Siderophore-binding proteins from two thermophilic bacteria, Geobacillus
stearothermophilus and Parageobacillus thermoglucosidasius, were identified
from a search of sequence databases, cloned and overexpressed. They are
homologues of the well characterized protein CjCeuE from Campylobacter
jejuni. The iron-binding histidine and tyrosine residues are conserved in both
thermophiles. Crystal structures were determined of the apo proteins and of
their complexes with iron(III)-azotochelin and its analogue iron(III)-5-LICAM.
The thermostability of both homologues was shown to be about 20C higher
than that of CjCeuE. Similarly, the tolerance of the homologues to the organic
solvent dimethylformamide (DMF) was enhanced, as reflected by the respective
binding constants for these ligands measured in aqueous buffer at pH 7.5 in the
absence and presence of 10% and 20% DMF. Consequently, these thermophilic
homologues offer advantages in the development of artificial metalloenzymes
using the CeuE family.
Original languageEnglish
Pages (from-to)694-705
Number of pages12
JournalActa Crystallographica Section D: Structural Biology
Early online date11 Jul 2023
Publication statusPublished - 28 Jul 2023


  • thermophilic proteins; siderophore binding; structure; biophysical characterization

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