Iron Coordination Properties of Gramibactin as Model for the New Class of Diazeniumdiolate Based Siderophores.

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 pL_0.5 . 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.

SUBMITTER: Gama S 

PROVIDER: S-EPMC7898861 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature