Iron coordination properties of gramibactin as model for the new class of diazeniumdiolate based siderophores.

Gama S, Hermenau R, Frontauria M, Milea D, Sammartano S, Hertweck C, Plass W (2020) Iron coordination properties of gramibactin as model for the new class of diazeniumdiolate based siderophores. Chemistry , PubMed

Abstract

Gramibactin (GBT) is an archetype for the new class of diazeniumdiolate siderophores, produced by Paraburkholderia graminis , a cereal-associated rhizosphere bacterium, for which a detailed solution thermodynamic study exploring the iron coordination properties is reported. The acid-base behavior of gramibactin as well as its complexing ability toward Fe 3+ was studied over a wide range of pH values (2 ≤ pH ≤ 11). For the latter the ligand-competition method employing EDTA was used. Only two species are formed: [Fe(GBT)] - (pH 2 to 9) and [Fe(GBT)(OH) 2 ] 3- (pH ≥ 9). The formation of [Fe(GBT)] - and its occurrence in real systems was confirmed by LC-HRESIMS analysis of the bacteria culture broth extract. The sequestering ability of gramibactin was also evaluated in terms of the parameters pFe and pL 0.5 . Gramibactin exhibits a higher sequestering ability toward Fe 3+ than EDTA and of the same order of magnitude as hydroxamate-type microbial siderophores, but smaller than most of the catecholate-type siderophores and much higher than the most known phytosiderophores.

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doi: 10.1002/chem.202003842 PMID: 33006390