Iron(III)-siderophore coordination chemistry: Reactivity of marine siderophores

Two remarkable features of many siderophores produced by oceanic bacteria are the prevalence of an alpha-hydroxy-carboxylic acid functionality either in the form of the amino acid beta-hydroxy aspartic acid or in the form of citric acid, as well as the predominance of amphiphilic siderophores. This review will provide an overview of the photoreactivity that takes place when siderophores containing beta-hydroxy aspartic acid and citric acid are coordinated to iron(III). This photoreactivity raises questions about the role of this photochemistry in microbial iron acquisition as well as upper-ocean iron cycling. The self-assembly of amphiphilic siderophores and the coordination-induced phase-change of the micelle-to-vesicle transformation will also be reviewed. The distinctive photosensitive and self-assembly properties of marine siderophores hint at possibly new microbial iron acquisition mechanisms. (C) 2009 Published by Elsevier B.V.