PMID:16987175

Citation	Grosse, C, Scherer, J, Koch, D, Otto, M, Taudte, N and Grass, G (2006) A new ferrous iron-uptake transporter, EfeU (YcdN), from Escherichia coli. Mol. Microbiol. 62:120-31
Abstract	Escherichia coli possesses multiple routes for iron uptake. Here we present EfeU (YcdN), a novel iron acquisition system of E. coli strain Nissle 1917. Laboratory strains of E. coli such as K12 lack a functional (efeU) ycdN gene caused by a frameshift mutation. EfeU, a member of the oxidase-dependent iron transporters (OFeT), is a homologue of the iron permease Ftr1p from yeast. The ycdN gene is part of the ycdNOB tricistronic operon which is expressed in response to iron deprivation in a Fur-dependent manner. Expression of efeU resulted in improved growth of an E. coli mutant lacking all known iron-uptake systems and mediated increased iron uptake into cells. Furthermore, the presence of other divalent metal cations did not impair growth of strains expressing efeU. The EfeU protein functioned as ferrous iron permease in proteoliposomes in vitro. Topology analysis indicated that EfeU is an integral cytoplasmic membrane protein exhibiting seven transmembrane helices. Two REXXE motifs within transmembrane helices of OFeT family members are implicated in iron translocation. Site-directed mutagenesis of each REGLE motif of EfeU diminished iron uptake in vivo and growth yield. In vitro the EfeU variant protein with an altered first REGLE motif was impaired in iron permeation, whereas activity of the EfeU variant with a mutation in the second motif was similar to the wild-type protein.
Links	PubMed Online version:10.1111/j.1365-2958.2006.05326.x
Keywords	Amino Acid Sequence; Biological Transport; Cation Transport Proteins/genetics; Cation Transport Proteins/metabolism; Cation Transport Proteins/physiology; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Escherichia coli Proteins/physiology; Gene Expression Regulation, Bacterial/genetics; Iron/metabolism; Iron/pharmacokinetics; Membrane Transport Proteins/genetics; Membrane Transport Proteins/metabolism; Membrane Transport Proteins/physiology; Molecular Sequence Data; Operon/genetics; Proteolipids/metabolism; Sequence Homology, Amino Acid
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ESCFE:A0A0W3CX36		GO:0034755: iron ion transmembrane transport	IDA: Inferred from Direct Assay:	P	Fig. 5 Fe56 uptake measured in E. coli K-12 GR536 [fecABCDE(del)::kan zupT(del)::cat mntH(del) feoABC(del) entC(del)] expressing a plasmid-borne copy of efeU gene from E. coli Nissle.	complete
ESCFE:A0A0W3CX36		GO:0098707: ferrous iron import across plasma membrane	IDA: Inferred from Direct Assay:	P	Fig. 6 purified protein reconstituted in proteoliposomes	complete
ESCFE:A0A0W3CX36		GO:0015639: ferrous iron uptake transmembrane transporter activity	IDA: Inferred from Direct Assay:	F	Fig.6	complete

References

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