Solution Structure of Escherichia coli FeoA and Its Potential Role in Bacterial Ferrous Iron Transport

Lau, Cecilia; Ishida, Hiroaki; Liu, Zhihong; Vogel, Hans J.

doi:10.1128/jb.01121-12

Cited by 52 publications

(65 citation statements)

References 77 publications

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“…The role of FeoA is not well defined, even though it is present in the majority of organisms that contain a Feo system (31). We investigated the role of FeoA in FeoB complex formation by mutational analysis.…”

Section: Discussionmentioning

confidence: 99%

“…FeoA is a small hydrophilic protein whose role is unknown, but it has been shown to be required for Feo function in several bacterial species (27)(28)(29). FeoA shows structural similarity to an Src-homology-3 (SH3) domain fold, suggesting that FeoA may mediate proteinprotein interactions (26,(30)(31)(32). FeoA was shown to interact with FeoB in a bacterial two-hybrid (BACTH) assay in Salmonella enterica (29).…”

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Vibrio cholerae FeoA, FeoB, and FeoC Interact To Form a Complex

2016

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Feo is the major ferrous iron transport system in prokaryotes. Despite having been discovered over 25 years ago and found to be widely distributed among bacteria, Feo is poorly understood, as its structure and mechanism of iron transport have not been determined. The feo operon in Vibrio cholerae is made up of three genes, encoding the FeoA, FeoB, and FeoC proteins, which are all required for Feo system function. FeoA and FeoC are both small cytoplasmic proteins, and their function remains unclear. FeoB, which is thought to function as a ferrous iron permease, is a large integral membrane protein made up of an N-terminal GTPase domain and a C-terminal membrane-spanning region. To date, structural studies of FeoB have been carried out using a truncated form of the protein encompassing only the N-terminal GTPase region. In this report, we show that full-length FeoB forms higher-order complexes when cross-linked in vivo in V. cholerae. Our analysis of these complexes revealed that FeoB can simultaneously associate with both FeoA and FeoC to form a large complex, an observation that has not been reported previously. We demonstrate that interactions between FeoB and FeoA, but not between FeoB and FeoC, are required for complex formation. Additionally, we identify amino acid residues in the GTPase region of FeoB that are required for function of the Feo system and for complex formation. These observations suggest that this large Feo complex may be the active form of Feo that is used for ferrous iron transport. IMPORTANCEThe Feo system is the major route for ferrous iron transport in bacteria. In this work, the Vibrio cholerae Feo proteins, FeoA, FeoB, and FeoC, are shown to interact to form a large inner membrane complex in vivo. This is the first report showing an interaction among all three Feo proteins. It is also determined that FeoA, but not FeoC, is required for Feo complex assembly. Iron is an indispensable component of enzymes involved in a wide range of biological processes and, as a result, is essential for life in almost all organisms (1). Notwithstanding the fact that iron is abundant in nature, aerobic, neutral-pH environments favor the formation of Fe(OH) 3 , a highly insoluble ferric iron (Fe 3ϩ ) complex. In contrast, in anoxic environments, free ferrous iron (Fe 2ϩ ) is more readily available (2). In order to meet their iron requirement, bacteria have multiple iron transport systems that allow use of the various forms of iron present in their environment, and Vibrio cholerae is no exception (3).V. cholerae is a human pathogen that causes cholera, a severe diarrheal disease resulting from the ingestion of contaminated food or water (4). V. cholerae must acquire iron from different environments, such as the gut of its human host or the fresh, brackish, and ocean waters that make up its natural habitat. This need to acquire the various forms of iron is reflected in the observation that approximately 1% of its genome is devoted to the acquisition of iron (3). In V. cholerae, ferric iron is commo...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Vibrio cholerae FeoA, FeoB, and FeoC Interact To Form a Complex

2016

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“…The feo operon from gammaproteobacteria encodes 3 proteins: FeoA, FeoB, and FeoC (11)(12)(13). FeoA, present in 90% of the feo operons, is a small Src homology 3 (SH3) domain protein necessary for ferrous iron transport (6,12,(14)(15)(16). Recent enzymatic assays have suggested that FeoA may not act as a GTPase-activating protein as originally proposed (14).…”

mentioning

confidence: 99%

“…FeoA, present in 90% of the feo operons, is a small Src homology 3 (SH3) domain protein necessary for ferrous iron transport (6,12,(14)(15)(16). Recent enzymatic assays have suggested that FeoA may not act as a GTPase-activating protein as originally proposed (14). FeoB, an indispensable component of the Feo system, is a large protein consisting of an intracellular amino-terminal domain (NFeoB) and a transmembrane carboxyl-terminal domain presumed to form the Fe 2ϩ pore function that functions as a permease.…”

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FeoC from Klebsiella pneumoniae Contains a [4Fe-4S] Cluster

Hsueh

Chen

et al. 2013

J Bacteriol

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Iron is essential for pathogen survival, virulence, and colonization. Feo is suggested to function as the ferrous iron (Fe 2؉ ) transporter. The enterobacterial Feo system is composed of 3 proteins: FeoB is the indispensable component and is a large membrane protein likely to function as a permease; FeoA is a small Src homology 3 (SH3) domain protein that interacts with FeoB; FeoC is a winged-helix protein containing 4 conserved Cys residues in a sequence suitable for harboring a putative iron-sulfur (Fe-S) cluster. The presence of an iron-sulfur cluster on FeoC has never been shown experimentally. We report that under anaerobic conditions, the recombinant Klebsiella pneumoniae FeoC (KpFeoC) exhibited hyperfine-shifted nuclear magnetic resonance (NMR) and a UV-visible (UV-Vis) absorbance spectrum characteristic of a paramagnetic center. The electron paramagnetic resonance (EPR) and extended X-ray absorption fine structure (EXAFS) results were consistent only with the [4Fe-4S] clusters. Substituting the cysteinyl sulfur with oxygen resulted in significantly reduced cluster stability, establishing the roles of these cysteines as the ligands for the Fe-S cluster. When exposed to oxygen, the [4Fe-4S] cluster degraded to [3Fe-4S] and eventually disappeared. We propose that KpFeoC may regulate the function of the Feo transporter through the oxygen-or iron-sensitive coordination of the Fe-S cluster.

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“…This gene is part of the Feo system, which has the function of transporting ferrous iron and has been associated with virulence in E. coli, Helicobacter pylori, Legionella pneumophila and Campylobacter jejuni [22]. Iron uptake appears to be one of the main virulence factors in strains of APEC.…”

Section: Discussionmentioning

confidence: 99%

Genes of Virulence and Phylogenetic Group in Isolates of Avian Pathogenic Escherichia coli

VHM¹,

IQ²,

PDPM³

et al. 2017

Arch Med

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Avian pathogenic Escherichia coli (APEC) shares some virulence attributes with strains of E. coli that cause extraintestinal infections in humans. The APEC is considered a possible cause for a zoonosis. The objective of this work was to determine the prevalence of twelve genes that are associated with virulence in a group of APEC isolates, as well as to identify the phylogenetic groups to which they belong. According to the results, one of these isolates harbors 91.6% of the virulence genes and most of the isolates have 7 or 8 of such twelve genes. The genes feoB and iss had the highest prevalence, with 95.6%. Genes associated to the acquisition of iron were present in more than 60% of the APEC isolates, while those of the ibeA invasin and vat toxin were detected with the lowest prevalence. A great genetic diversity was observed on the APEC isolates, which suggest that bacterial systems for iron acquisition, and those related to bacterial resistance to the host's defense mechanisms are fundamental virulence factors in these bacteria. On the other hand, the rest of the virulence genes provide valuable information for the development of vaccines against avian colibacillosis. It was also determined that a high percentage of APEC belongs to the phylogenetic group B1, from which mainly commensal and pathogenic E. coli strains derive.

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Solution Structure of Escherichia coli FeoA and Its Potential Role in Bacterial Ferrous Iron Transport

Cited by 52 publications

References 77 publications

Vibrio cholerae FeoA, FeoB, and FeoC Interact To Form a Complex

Vibrio cholerae FeoA, FeoB, and FeoC Interact To Form a Complex

FeoC from Klebsiella pneumoniae Contains a [4Fe-4S] Cluster

Genes of Virulence and Phylogenetic Group in Isolates of Avian Pathogenic Escherichia coli

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