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 (2021) Iron coordination properties of gramibactin as model for the new class of diazeniumdiolate based siderophores. Chemistry 27(8), 2724-2733.

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 Fe3+ 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 pL0.5 . Gramibactin exhibits a higher sequestering ability toward Fe3+ 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.

Leibniz-HKI-Authors

Ron Hermenau
Christian Hertweck

Identifier

doi: 10.1002/chem.202003842

PMID: 33006390