SBIC ECR Symposium & Poster Presentation 21st International Conference on Biological Inorganic Chemistry 2025

Unveiling the coordination secrets of aryloxazoline and arylthiazoline siderophores (#416)

Klaudia Szczerba 1 , Andrzej Mular 1 , Karolina Piasta 1 , Karolina Kaminska 1 2 , Elzbieta Wojaczynska 2 , Henryk Kozlowski 1 3 , Oscar Palacios 4 , Merce Capdevila 4 , Elzbieta Gumienna-Kontecka 1
  1. Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland
  2. Faculty of Chemistry, Wroclaw University of Science and Technology, Wroclaw, Poland
  3. Institute of Health Sciences, University of Opole, Opole, Poland
  4. Departament de Química, Universitat Autònoma de Barcelona, Barcelona, Spain

Siderophores, which are low molecular weight molecules, are secreted by microorganisms to scavenge, uptake and control iron levels.1 Interestingly, they are also able to bind other metal ions.2 Siderophores are not recognized by animal organisms which predisposes them to be used in medicine as fluorescent probes or therapeutic substances to pathogenic cells.3,4

In this research we focus on the determination of the coordination properties of aryloxazoline and arylthiazoline siderophores, which comprise phenol/catechol and oxazoline/thiazoline heterocycle together with other binding units.5 The most known representative is Yersiniabactin, able to bind Cu(II) ions as a part of bacterial defense against host macrophages, while maintaining active transport of Fe(III) ions.6,7 We aim at understanding how structural changes affect the stability of the formed complexes with Fe(III) and other metal ions, and learn which siderophore binding groups are crucial for an efficient chelation.

For the determination of the physico-chemical properties of simplified analogs of siderophores such as Yersiniabactin or Pre-pseudomonine, and the stability constants of their complexes with Fe(III) and Cu(II) ions, potentiometry and UV-Vis spectroscopy were used. The environment of the Cu(II) ion changing with increasing pH during UV-Vis titration was analyzed simultaneously using EPR spectroscopy. The metal to ligand ratio was confirmed by mass spectrometry.

All studied chelators create stable complexes with both Fe(III) and Cu(II) ions. The details on coordination pattern and differences in stabilities will be discussed to revel which binding units are primary for an efficient chelation.

 

Acknowledgements

Financial support by the Polish National Science Centre (UMO-2017/26/A/ST5/00363 and UMO-2022/47/I/ST4/02354) is gratefully acknowledged.

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