Kammler M, Schön C, Hantke K.. Characterization of the ferrous iron uptake system of Escherichia coli. J Bacteriol 175: 6212-6219

Lehrstuhl für Mikrobiologie II, Universität Tübingen, Germany.
Journal of Bacteriology (Impact Factor: 2.81). 11/1993; 175(19):6212-9.
Source: PubMed


Escherichia coli has an iron(II) transport system (feo) which may make an important contribution to the iron supply of the cell under anaerobic conditions. Cloning and sequencing of the iron(II) transport genes revealed an open reading frame (feoA) possibly coding for a small protein with 75 amino acids and a membrane protein with 773 amino acids (feoB). The upstream region of feoAB contained a binding site for the regulatory protein Fur, which acts with iron(II) as a corepressor in all known iron transport systems of E. coli. In addition, a Fnr binding site was identified in the promoter region. The FeoB protein had an apparent molecular mass of 70 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was localized in the cytoplasmic membrane. The sequence revealed regions of homology to ATPases, which indicates that ferrous iron uptake may be ATP driven. FeoA or FeoB mutants could be complemented by clones with the feoA or feoB gene, respectively.

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Available from: Klaus Hantke, Dec 08, 2014
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    • "For Cu 2+ transport, the E. hirae membrane P-type ATPases (CopA and CopB) are responsible. Fe 2+ uptake is an ATP-driven process and the appropriate transport system is encoded by three feoABC genes (Kammler et al., 1993), while Fe 3+ is taken up together with siderophores (Ouyang and Isaacson, 2006). The Fe 3+ -siderophore complex passes through the plasma membrane together with specific proteins that are components of ABC transporters (Ouyang and Isaacson, 2006). "
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    ABSTRACT: Pollution by various heavy metals as environmental stress factors might affect bacteria. It was established that iron (Fe(III)), manganese (Mn(II)) and copper (Cu(II)) ion combinations caused effects on Enterococcus hirae that differed from the sum of the effects when the metals were added separately. It was shown that the Cu2 +–Fe3 + combination decreased the growth and ATPase activity of membrane vesicles of wild-type E. hirae ATCC9790 and atpD mutant (with defective FoF1-ATPase) MS116. Addition of Mn2 +–Fe3 + combinations within the same concentration range had no effects on growth compared to control (without heavy metals). ATPase activity was increased in the presence of Mn2 +–Fe3 +, while together with 0.2 mmol/L N,N′-dicyclohexylcarbodiimide (DCCD), ATPase activity was decreased compared to control (when only 0.2 mmol/L DCCD was present). These results indicate that heavy metals ion combinations probably affect the FOF1-ATPase, leading to conformational changes. Moreover the action may be direct or be mediated by environment redox potential. The effects observed when Fe3 + was added separately disappeared in both cases, which might be a result of competing processes between Fe3 + and other heavy metals. These findings are novel and improve the understanding of heavy metals ions effects on bacteria, and could be applied for regulation of stress response patterns in the environment.
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    • "These results suggested that the observed growth delay of the ΔfeoB′ mutant on agar was likely due to a deficiency in iron acquisition. Small colony morphology associated with reduced iron acquisition has been previously reported in LVS as well as in E. coli feo mutants [39], [26]. The discrepancy in liquid and agar growth phenotypes may be explained by the fact that the iron is likely in the oxidized ferric form during growth with shaking in liquid, while the agar medium with a high concentration of cysteine (required supplement since F. tularensis is a cysteine auxotroph) would maintain much of the iron in the reduced ferrous form. "
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    ABSTRACT: Bacterial pathogens require multiple iron-specific acquisition systems for survival within the iron-limiting environment of the host. Francisella tularensis is a virulent intracellular pathogen that can replicate in multiple cell-types. To study the interrelationship of iron acquisition capability and virulence potential of this organism, we generated single and double deletion mutants within the ferrous iron (feo) and ferric-siderophore (fsl) uptake systems of the live vaccine strain (LVS). The Feo system was disrupted by a partial deletion of the feoB gene (ΔfeoB'), which led to a growth defect on iron-limited modified Muller Hinton agar plates. 55Fe uptake assays verified that the ΔfeoB' mutant had lost the capacity for ferrous iron uptake but was still competent for 55Fe-siderophore-mediated ferric iron acquisition. Neither the ΔfeoB' nor the siderophore-deficient ΔfslA mutant was defective for replication within J774A.1 murine macrophage-like cells, thus demonstrating the ability of LVS to survive using either ferrous or ferric sources of intracellular iron. A LVS ΔfslA ΔfeoB' mutant defective for both ferrous iron uptake and siderophore production was isolated in the presence of exogenous F. tularensis siderophore. In contrast to the single deletion mutants, the ΔfslA ΔfeoB' mutant was unable to replicate within J774A.1 cells and was attenuated in virulence following intraperitoneal infection of C57BL/6 mice. These studies demonstrate that the siderophore and feoB-mediated ferrous uptake systems are the only significant iron acquisition systems in LVS and that they operate independently. While one system can compensate for loss of the other, both are required for optimal growth and virulence.
    Full-text · Article · Apr 2014 · PLoS ONE
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    • "Two FutA homologs, FutA1 and FutA2, were identified and shown to bind Fe(III) (Katoh et al., 2001; Badarau et al., 2008). In addition, a protein homologous to the Escherichia coli Fe(II) transporter, FeoB (Kammler et al., 1993), was shown to be involved in Fe(II) acquisition (Table 1, Katoh et al., 2001). "
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