Iron (III) hydroxamate transport into Escherichia coli. Substrate binding to the periplasmic FhuD protein.

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Koster W, Braun V

Iron (III) hydroxamate transport into Escherichia coli. Substrate binding to the periplasmic FhuD protein.

J Biol Chem. 1990 Dec 15;265(35):21407-10.

PubMed ID

2254301 [ View in PubMed

]

Abstract

Due to its extreme insolubility, Fe3+ is not transported as a monoatomic ion. In microbes, iron is bound to low molecular weight carriers, designated siderophores. For uptake into cells of Escherichia coli Fe3+ siderophores have to be translocated across two membranes. Transport across the outer membrane is receptor-dependent and energy-coupled; transport across the cytoplasmic membrane seems to follow a periplasmic binding protein-dependent transport mechanism. In support of this notion we demonstrate specific binding of the Fe3+ hydroxamate compounds ferrichrome, aerobactin, and coprogen, which are transported via the Fhu system, to the periplasmic FhuD protein, and no binding of the transport inactive ferrichrome A, ferric citrate, and iron sulfate. About 10(4) ferrichrome molecules were bound to the FhuD protein of cells which overproduced plasmid-encoded FhuD. Binding depended on transport across the outer membrane mediated by the FhuA receptor and the TonB protein. Binding to FhuD was supported by the exclusive resistance of FhuD to proteinase K in the presence of the transport active hydroxamates. The overproduced precursor form of the FhuD protein was not protected by the Fe3+ hydroxamates indicating a conformation different to the mature form. The FhuD protein apparently serves as a periplasmic carrier for Fe3+ hydroxamates with widely different structures.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Ferric cation	Iron(3+)-hydroxamate-binding protein FhuD	Protein	Escherichia coli (strain K12)	Unknown	Binder	Details
Tetraferric tricitrate decahydrate	Iron(3+)-hydroxamate-binding protein FhuD	Protein	Escherichia coli (strain K12)	Unknown	Binder	Details