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Crochelins: Siderophores with an Unprecedented Iron‐Chelating Moiety from the Nitrogen‐Fixing Bacterium Azotobacter chroococcum
Author(s) -
Baars Oliver,
Zhang Xinning,
Gibson Marcus I.,
Stone Alan T.,
Morel François M. M.,
Seyedsayamdost Mohammad R.
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201709720
Subject(s) - siderophore , azotobacter chroococcum , chelation , chemistry , moiety , azotobacter vinelandii , bacteria , biochemistry , nitrogen fixation , stereochemistry , biology , nitrogenase , organic chemistry , nitrogen , genetics , gene
Microbes use siderophores to access essential iron resources in the environment. Over 500 siderophores are known, but they utilize a small set of common moieties to bind iron. Azotobacter chroococcum expresses iron‐rich nitrogenases, with which it reduces N 2 . Though an important agricultural inoculant, the structures of its iron‐binding molecules remain unknown. Here, the “chelome” of A. chroococcum is examined using small molecule discovery and bioinformatics. The bacterium produces vibrioferrin and amphibactins as well as a novel family of siderophores, the crochelins. Detailed characterization shows that the most abundant member, crochelin A, binds iron in a hexadentate fashion using a new iron‐chelating γ‐amino acid. Insights into the biosynthesis of crochelins and the mechanism by which iron may be removed upon import of the holo‐siderophore are presented. This work expands the repertoire of iron‐chelating moieties in microbial siderophores.