GO:0015093 ferrous iron transmembrane transporter activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015093 describes the molecular function of moving ferrous iron (Fe2+) ions across a membrane, a process distinct from ferric iron transport.
• Bacteria use dedicated Fe2+ uptake systems such as EfeU (YcdN) and Feo to acquire iron under anaerobic or low-pH conditions.
• In humans, duodenal cytochrome b (DCYTB) reduces dietary Fe3+ to Fe2+ for transport, linking redox state to iron absorption.
• Cytokine-mediated regulation of iron transport in monocytic cells highlights the role of this activity in immunity and inflammation.
• Plant IRT1 is a well-studied Fe2+ transporter required for root-to-shoot iron partitioning, though its transport function can be uncoupled from certain developmental roles.
• CRISPR knockout, point-mutation, and knock-in models are essential to dissect the causal contribution of Fe2+ transporters to physiology and disease.
Description
Ferrous iron (Fe2+) is the reduced form of iron that is soluble and bioavailable under physiological conditions, and its movement across cellular membranes is a fundamental process in all kingdoms of life. The Gene Ontology term GO:0015093, ferrous iron transmembrane transporter activity, defines the molecular function that enables this transfer of Fe2+ ions from one side of a membrane to the other. This activity is distinct from the transport of ferric iron (Fe3+), which often requires reduction or siderophore-mediated uptake. Understanding GO:0015093 is critical because iron is both essential for processes such as respiration and DNA synthesis and toxic when in excess, so its uptake must be tightly regulated. Researchers study ferrous iron transporters to uncover how organisms acquire iron in diverse environments, from the anaerobic gut of bacteria to the duodenal mucosa of mammals. In bacteria, Fe2+ uptake systems like EfeU and Feo are often expressed when iron is scarce or when oxygen is limited, and their activities influence virulence and colonization. In fungi, contrasting strategies of internal versus external reduction precede Fe2+ transport, illustrating evolutionary diversity in this function. In plants, the IRON-REGULATED TRANSPORTER1 (IRT1) mediates Fe2+ uptake at the root surface, and its role in root-to-shoot partitioning has been genetically separated from its transport activity. In humans, cytokines modulate iron transport in monocytic cells, linking GO:0015093 to host defense and inflammation. Because ferrous iron transport is a point of vulnerability for pathogens and a critical control node in human iron homeostasis, it is a prime target for genetic and pharmacological interrogation. This article synthesizes authoritative QuickGO annotations and verified PubMed literature to provide a research-grade overview of GO:0015093, its mechanisms, key genes, and the CRISPR-based methods used to study it.
ferrous iron transmembrane transporter activity At A Glance
| GO ID | GO:0015093 |
|---|---|
| GO term | ferrous iron transmembrane transporter activity |
| Ontology | molecular_function |
| Synonym | ferrous iron uptake transmembrane transporter activity |
| Major function | Enables the transfer of ferrous iron (Fe2+) ions across a membrane. |
| Substrate | Ferrous iron (Fe(II) or Fe2+) |
| Directionality | Transmembrane transfer from one side of a membrane to the other. |
| Related activity | Iron ion transmembrane transporter activity (parent term). |
| Organisms | Bacteria, fungi, plants, and animals, including humans. |
What Is GO:0015093?
GO:0015093, ferrous iron transmembrane transporter activity, is a molecular function that enables the transfer of ferrous iron (Fe(II) or Fe2+) ions from one side of a membrane to the other. This activity is synonymous with ferrous iron uptake transmembrane transporter activity. It is a type of iron ion transmembrane transporter activity that specifically handles the reduced form of iron, as opposed to ferric iron (Fe3+) transport, which may involve different proteins and mechanisms.
Why Is ferrous iron transmembrane transporter activity Important in Cell Biology?
Ferrous iron transmembrane transporter activity is essential for iron acquisition in nearly all organisms, and its dysregulation contributes to infectious disease, anemia, and iron overload disorders. Because Fe2+ is the soluble, reduced form of iron, its transport is often the rate-limiting step in cellular iron uptake, particularly in anaerobic or acidic environments where Fe3+ is poorly soluble. In bacterial pathogens, Fe2+ transporters such as Feo and EfeU are critical for colonization and virulence, making them attractive targets for new antibiotics. In humans, the reduction of dietary Fe3+ to Fe2+ by DCYTB is a prerequisite for intestinal absorption, and cytokine-mediated changes in iron transport in monocytes affect both host defense and anemia of inflammation. In plants, IRT1-mediated Fe2+ uptake is required for proper iron distribution, and its loss causes severe growth defects. Thus, GO:0015093 sits at the intersection of microbiology, immunology, plant nutrition, and human medicine.
• Enables iron acquisition in bacteria, fungi, plants, and animals, supporting respiration and DNA synthesis.
• Critical for virulence of bacterial pathogens such as Escherichia coli and Vibrio cholerae.
• Required for dietary iron absorption in mammals via reduction of Fe3+ to Fe2+ by DCYTB.
• Modulated by cytokines in human monocytic cells, linking iron transport to inflammation and immunity.
• Involved in root-to-shoot iron partitioning in plants, affecting crop yield and nutritional quality.
• Represents a potential drug target for antimicrobials and for modulating iron homeostasis in disease.
• Its dysfunction may contribute to iron deficiency or overload, though direct human mutations are less characterized.
• Provides a model for studying membrane protein evolution and metal selectivity.
What Happens During ferrous iron transmembrane transporter activity?
Substrate recognition and binding
In simple terms: The transporter first grabs a ferrous iron ion from one side of the membrane.
Ferrous iron transporters must selectively recognize Fe2+ in the presence of other divalent cations. In Escherichia coli, the EfeU (YcdN) protein is a newly identified ferrous iron-uptake transporter that likely binds Fe2+ with high affinity under low-iron conditions. Similarly, the Feo system is a major ferrous iron transport system in bacteria, and its evolutionary history suggests ancient origins and diverse substrate-binding strategies. In fungi, both internal and external reduction mechanisms precede Fe2+ binding, ensuring that the transporter encounters the reduced form.
Membrane translocation
In simple terms: The transporter moves the iron ion across the membrane barrier.
Once bound, the transporter undergoes conformational changes to shuttle Fe2+ across the lipid bilayer. This step is energy-dependent in many systems, often coupling to proton motive force or ATP hydrolysis, though the exact mechanism varies. In Vibrio cholerae, the VciB protein mediates iron reduction, which may be a prerequisite for subsequent Fe2+ transport. The translocation process is tightly controlled to avoid uncontrolled iron influx, which could be toxic.
Iron reduction and redox coupling
In simple terms: Sometimes iron must be converted from its oxidized form to the reduced form before transport.
Many organisms reduce Fe3+ to Fe2+ before transport. In mammals, duodenal cytochrome b (DCYTB) performs this reduction at the intestinal brush border, enabling subsequent Fe2+ uptake. In Vibrio cholerae, VciB mediates iron reduction, likely facilitating Fe2+ availability for transport. Fungi can use either internal or external reduction strategies, depending on the species and environmental conditions. This redox coupling ensures that the substrate for GO:0015093 is available.
Regulation of transport activity
In simple terms: The cell adjusts how much iron it takes up based on need and stress.
Ferrous iron transport is regulated at multiple levels. In human monocytic cells, cytokines such as interferon-gamma and tumor necrosis factor-alpha modulate iron transport, linking immune signals to iron homeostasis. In bacteria, iron-responsive regulators control the expression of Feo and EfeU systems in response to iron availability. In plants, IRT1 expression is induced under iron deficiency, but its transport function can be uncoupled from certain developmental roles, indicating post-translational regulation.
Key Genes Involved in GO:0015093 ferrous iron transmembrane transporter activity
The following genes and proteins are experimentally validated players in ferrous iron transmembrane transporter activity or its regulation, based on the cited literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| efeU (ycdN) | Ferrous iron uptake transporter in Escherichia coli | Model for bacterial Fe2+ acquisition under low iron |
| feoB | Major ferrous iron transport system in bacteria | Evolutionary and mechanistic studies of Fe2+ uptake |
| DCYTB (CYBRD1) | Duodenal cytochrome b, reduces Fe3+ to Fe2+ for absorption | Human iron absorption and redox coupling |
| VciB | Mediates iron reduction in Vibrio cholerae | Links reduction to Fe2+ transport in pathogens |
| IRT1 | Root Fe2+ transporter in Arabidopsis | Plant iron uptake and root-to-shoot partitioning |
| FTR1 | High-affinity Fe2+ permease in fungi | Fungal iron uptake with internal or external reduction |
| FET3 | Ferroxidase involved in high-affinity iron uptake in yeast | Coupled to Fe2+ transport after reduction |
| SLC11A1 (NRAMP1) | Natural resistance-associated macrophage protein 1 | Macrophage iron transport and immunity |
| SLC11A2 (DMT1) | Divalent metal transporter 1 | Intestinal Fe2+ uptake and endosomal transport |
| Ferroportin (SLC40A1) | Iron exporter | Basolateral iron transfer after uptake |
| Hephaestin | Ferroxidase aiding iron export | Coupled to Fe2+ oxidation after transport |
| Ferritin | Iron storage protein | Buffers intracellular Fe2+ after transport |
| Transferrin receptor 1 (TFRC) | Mediates transferrin-bound iron uptake | Alternative iron uptake pathway |
| IRP1/IRP2 | Iron regulatory proteins | Post-transcriptional regulation of iron transport genes |
| HIF-2α | Hypoxia-inducible factor | Regulates iron transport genes in hypoxia |
| Nramp1 (Slc11a1) | Macrophage Fe2+ transporter | Host defense against intracellular pathogens |
| ZIP8 (SLC39A8) | Zinc/iron transporter | Overlapping metal transport functions |
| ZIP14 (SLC39A14) | Zinc/iron transporter | Iron handling in hepatocytes |
How Is ferrous iron transmembrane transporter activity Regulated?
Ferrous iron transmembrane transporter activity is regulated at transcriptional, post-transcriptional, and post-translational levels. In bacteria, iron-responsive repressors such as Fur control the expression of Feo and EfeU systems in response to iron availability. In mammals, the iron regulatory proteins IRP1 and IRP2 bind to iron-responsive elements in mRNAs of transport proteins like DMT1 and ferroportin, adjusting their translation according to cellular iron levels. Cytokines such as interferon-gamma and tumor necrosis factor-alpha can modulate iron transport in monocytic cells, linking immune signaling to GO:0015093. In plants, IRT1 is induced under iron deficiency, but its transport function can be uncoupled from certain developmental roles, suggesting additional layers of regulation.
ferrous iron transmembrane transporter activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| DCYTB (CYBRD1) | Iron deficiency anemia | Intestinal epithelial cell knockout |
| SLC11A1 (NRAMP1) | Susceptibility to intracellular pathogens | Macrophage knockout |
| feoB | Bacterial virulence | E. coli knockout |
| efeU (ycdN) | Bacterial iron acquisition | E. coli knockout |
| IRT1 | Plant iron deficiency chlorosis | Arabidopsis knockout |
Iron deficiency and anemia
Impaired ferrous iron transport can lead to reduced iron absorption and anemia. DCYTB is required for the reduction of dietary Fe3+ to Fe2+, a prerequisite for intestinal Fe2+ uptake, and its dysfunction may contribute to iron deficiency. Cytokine-mediated regulation of iron transport in monocytic cells is also linked to anemia of inflammation, where inflammatory signals reduce iron availability.
Bacterial infections and virulence
Ferrous iron transporters are critical for bacterial pathogens to acquire iron from the host. Escherichia coli EfeU and Feo systems enable iron uptake under low-iron conditions, supporting colonization and virulence. Vibrio cholerae VciB mediates iron reduction, which may facilitate Fe2+ transport and contribute to pathogenesis. Targeting these transporters could provide new antibacterial strategies.
Iron overload and neurodegeneration
Excessive ferrous iron transport can contribute to iron overload and oxidative stress. In humans, dysregulated iron transport in macrophages and other cells may exacerbate conditions such as hemochromatosis and neurodegenerative diseases, though direct evidence for GO:0015093 mutations in these diseases is still emerging. Plant IRT1 studies show that misregulated Fe2+ uptake causes growth defects, highlighting the importance of tight control.
From ferrous iron transmembrane transporter activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a ferrous iron transporter reduce iron uptake? | CRISPR knockout in cell lines or bacteria |
| Does a point mutation alter substrate specificity? | CRISPR point mutation knock-in |
| Can a tagged transporter be used for localization studies? | Knock-in of fluorescent or epitope tag |
| Does overexpression increase iron accumulation? | CRISPR overexpression or cDNA overexpression |
| Which genes regulate ferrous iron transport? | CRISPR library screening |
| How does cytokine signaling affect iron transport? | Knockout of cytokine receptors in monocytes |
How to Study the ferrous iron transmembrane transporter activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| CRISPR knockout | Loss of gene function | Testing necessity of transporter |
| CRISPR point mutation | Effect of specific amino acid changes | Dissecting mechanism |
| Knock-in tagging | Protein localization and interactions | Visualizing transporter |
| RNA-seq | Transcriptional changes | Identifying regulated transporters |
| Proteomics | Protein abundance and modifications | Validating expression changes |
| Iron uptake assays | Direct Fe2+ transport activity | Functional validation |
| CRISPR library screening | Genome-wide identification of regulators | Discovering new players |
Genetic knockout and knockdown
CRISPR-Cas9 knockout of candidate ferrous iron transporter genes in bacterial, plant, or mammalian cells allows direct assessment of their contribution to iron uptake. For example, deletion of efeU in Escherichia coli reduces ferrous iron uptake under low-iron conditions. Similarly, feoB mutants are defective in ferrous iron transport, confirming its role.
Point mutation and knock-in
Introducing specific point mutations in transporter genes can dissect residues critical for Fe2+ binding or translocation. In Arabidopsis, separation of IRT1 transport function from developmental roles was achieved using genetic mutants. Knock-in of tagged versions enables localization and interaction studies.
Transcriptomics and proteomics
RNA-seq and proteomics can reveal changes in expression of ferrous iron transporters under different iron conditions or cytokine treatments. Cytokine-mediated regulation of iron transport in monocytic cells was studied using such approaches. In bacteria, iron-responsive regulons can be mapped by transcriptomics.
Functional transport assays
Direct measurement of Fe2+ transport using radioactive or fluorescent iron probes is essential to confirm GO:0015093 activity. Such assays have been used to characterize EfeU and Feo systems. In plants, iron uptake assays in roots demonstrate IRT1 activity.
How CRISPR Can Be Used to Study GO:0015093 ferrous iron transmembrane transporter activity
Knockout
CRISPR knockout of ferrous iron transporter genes such as efeU or feoB in bacteria, or IRT1 in plants, provides definitive evidence of their role in Fe2+ uptake. In mammalian cells, knockout of DCYTB or SLC11A1 can reveal effects on iron homeostasis and immune function.
Point Mutation
Point mutations introduced by CRISPR base editing or homology-directed repair can test the importance of specific residues in Fe2+ binding or translocation. For example, mutations in IRT1 have been used to separate its transport function from developmental roles. Such models are valuable for structure-function studies.
Knock-in
Knock-in of epitope tags or fluorescent proteins allows real-time tracking of ferrous iron transporters in live cells. This approach has been used to localize DCYTB and other iron-related proteins. Tagged knock-ins also facilitate co-immunoprecipitation to identify interaction partners.
Overexpression
CRISPR activation or cDNA overexpression of ferrous iron transporters can increase iron uptake and reveal downstream effects. Overexpression of fungal FTR1 or plant IRT1 enhances Fe2+ transport, providing gain-of-function models. These models are useful for testing inhibitors or studying iron overload.
How EDITGENE Supports ferrous iron transmembrane transporter activity Research
Researchers studying ferrous iron transmembrane transporter activity-related genes often need to determine whether a candidate gene is causally involved in iron uptake, how specific mutations affect transport, and which regulatory networks control its expression. EDITGENE provides end-to-end CRISPR solutions to answer these questions with precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for ferrous iron transmembrane transporter activity research.
Frequently Asked Questions About ferrous iron transmembrane transporter activity
What is GO:0015093?
GO:0015093 is the Gene Ontology term for ferrous iron transmembrane transporter activity, the molecular function that enables the transfer of Fe2+ ions across a membrane.
What genes are involved in ferrous iron transmembrane transporter activity?
Key genes include efeU (ycdN) and feoB in bacteria, DCYTB and SLC11A1 in humans, IRT1 in plants, and FTR1 in fungi.
How is ferrous iron transported across membranes?
Ferrous iron transporters bind Fe2+ and undergo conformational changes to move the ion across the lipid bilayer, often coupled to reduction of Fe3+ to Fe2+.
Why is ferrous iron transport important for bacteria?
It allows bacteria to acquire iron for essential processes and contributes to virulence, making it a potential drug target.
What is the role of DCYTB in iron metabolism?
DCYTB reduces dietary Fe3+ to Fe2+ at the intestinal brush border, enabling subsequent ferrous iron transport.
How do cytokines affect ferrous iron transport?
Cytokines such as interferon-gamma modulate iron transport in monocytic cells, linking immune signaling to iron homeostasis.
Can CRISPR be used to study ferrous iron transporters?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are powerful tools to dissect transporter function.
What diseases are linked to ferrous iron transport?
Iron deficiency anemia, bacterial infections, and iron overload disorders are associated with altered ferrous iron transport.
How is ferrous iron transport regulated in plants?
IRT1 expression is induced under iron deficiency, and its transport function can be uncoupled from developmental roles.
What methods measure ferrous iron transport activity?
Functional assays using radioactive or fluorescent iron, combined with genetic and omics approaches, are commonly used.
Conclusion
GO:0015093, ferrous iron transmembrane transporter activity, is a fundamental molecular function that underpins iron acquisition across all domains of life. From bacterial pathogens using EfeU and Feo systems to human intestinal absorption via DCYTB and plant root uptake by IRT1, this activity is tightly regulated and essential for health and disease. Dysregulation contributes to anemia, infections, and iron overload, making it a compelling target for research and therapeutic intervention. CRISPR-based models are indispensable for dissecting the causal roles of ferrous iron transporters and their regulators. EDITGENE offers comprehensive services to generate knockout, point-mutation, knock-in, and overexpression models, as well as library screening and bioinformatics support, empowering researchers to advance the field of iron biology.
References
- 1. Grosse C et al.. 2006. A new ferrous iron-uptake transporter, EfeU (YcdN), from Escherichia coli.. Mol Microbiol 62(1):120-31 PMID: 16987175
- 2. Lane DJ et al.. 2015. Duodenal cytochrome b (DCYTB) in iron metabolism: an update on function and regulation.. Nutrients 7(4):2274-96 PMID: 25835049
- 3. Braun V. 2003. Iron uptake by Escherichia coli.. Front Biosci 8:s1409-21 PMID: 12957834
- 4. Peng ED et al.. 2017. Vibrio cholerae VciB Mediates Iron Reduction.. J Bacteriol 199(12) PMID: 28348025
- 5. Gómez-Garzón C et al.. 2022. Disentangling the Evolutionary History of Feo, the Major Ferrous Iron Transport System in Bacteria.. mBio 13(1):e0351221 PMID: 35012344
- 6. De Luca NG et al.. 2000. Iron uptake by fungi: contrasted mechanisms with internal or external reduction.. Adv Microb Physiol 43:39-74 PMID: 10907554
- 7. Quintana J et al.. 2022. Root-to-shoot iron partitioning in Arabidopsis requires IRON-REGULATED TRANSPORTER1 (IRT1) protein but not its iron(II) transport function.. Plant J 109(4):992-1013 PMID: 34839543
- 8. Ludwiczek S et al.. 2003. Cytokine-mediated regulation of iron transport in human monocytic cells.. Blood 101(10):4148-54 PMID: 12522003
