GO:0008199 ferric iron binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0008199 ferric iron binding is a molecular function defined as binding to a ferric iron ion, Fe(III).
• Ferric iron binding proteins coordinate Fe(III) through oxygen and nitrogen ligands, often with anion-independent coordination.
• Key proteins include FbpA in Neisseria, KfuA in Klebsiella pneumoniae, and FecA in Escherichia coli.
• Ferric iron uptake systems are critical for virulence in pathogens such as Flavobacterium columnare and Vibrio vulnificus.
• Siderophore-dependent ferrichelatases and ferric iron-binding proteins are promising targets for antimicrobial development.
• Research methods include structural biology, mutagenesis, and CRISPR-based knockout models to study ferric iron binding.
Description
Ferric iron binding (GO:0008199) is a molecular function that enables a protein to selectively bind Fe(III), the oxidized form of iron that is abundant in aerobic environments but poorly soluble. This function is essential for iron acquisition, transport, and homeostasis across all domains of life, from bacteria to humans. In pathogens, ferric iron binding proteins are often virulence factors that scavenge iron from host proteins. Understanding the structural and mechanistic basis of ferric iron binding is therefore critical for developing new antibiotics and for understanding iron-related diseases.
ferric iron binding At A Glance
| GO ID | GO:0008199 |
|---|---|
| GO term | ferric iron binding |
| Ontology | molecular_function |
| Synonym | none |
| Definition | Binding to a ferric iron ion, Fe(III). |
| Major function | Selective binding of Fe(III) for transport, storage, or catalysis. |
| Representative proteins | FbpA, KfuA, FecA, ferrichelatases |
| Cellular context | Periplasm, outer membrane, secreted proteins |
| Disease relevance | Bacterial virulence, iron overload disorders |
What Is GO:0008199?
According to the Gene Ontology, GO:0008199 ferric iron binding is defined as the molecular function of binding to a ferric iron ion, Fe(III). This term describes the selective interaction between a protein and Fe(III), typically through coordination by amino acid side chains such as histidine, tyrosine, aspartate, and glutamate. The binding event can occur in various contexts, including transport, storage, and enzymatic catalysis.
Why Is ferric iron binding Important in Cell Biology?
Ferric iron binding is fundamental to iron homeostasis and host-pathogen interactions. In bacteria, ferric iron binding proteins are required for iron uptake and virulence, making them attractive drug targets. In humans, dysregulation of ferric iron binding can lead to iron overload and neurodegenerative diseases. The molecular details of Fe(III) coordination inform the design of inhibitors and therapeutic chelators.
• Essential for bacterial iron acquisition and virulence.
• Target for novel antibiotics and anti-virulence strategies.
• Involved in host iron transport and storage.
• Provides structural insights into anion-independent metal coordination.
• Relevant to iron overload disorders and neurodegeneration.
• Facilitates siderophore-mediated iron uptake.
• Key to understanding TonB-dependent transport.
• Enables survival in iron-limited environments.
• Model system for studying protein-metal interactions.
• Potential for bioremediation of iron-contaminated sites.
Molecular Mechanism of ferric iron binding
Fe(III) Coordination Chemistry
In simple terms: Ferric iron is bound by protein side chains that donate oxygen or nitrogen atoms.
Ferric iron binding proteins typically coordinate Fe(III) through oxygen atoms from tyrosinate, aspartate, or glutamate, and nitrogen atoms from histidine. The coordination geometry is often octahedral, with the metal ion chelated by multiple ligands. In Campylobacter jejuni FbpA, coordination is anion-independent, using only protein side chains. Similarly, Neisseria FbpA coordinates iron in a manner homologous to transferrins.
Structural Basis of Binding
In simple terms: The protein folds into a pocket that holds the iron ion tightly.
Structures of ferric iron binding proteins reveal a bilobed fold with a central iron-binding cleft. KfuA from Klebsiella pneumoniae shows a typical ferric-binding protein fold with conserved ligands. FecA, a TonB-dependent transporter, binds ferric citrate with a distinct mechanism involving extracellular loops. These structures explain how proteins achieve high affinity and selectivity for Fe(III).
Siderophore-Mediated Uptake
In simple terms: Some bacteria use small molecules called siderophores to capture iron and deliver it to binding proteins.
Siderophore-dependent ferrichelatases hydrolyze siderophores to release iron, which is then bound by ferric iron binding proteins. This system is critical for iron acquisition in pathogens like Vibrio vulnificus. The interplay between siderophores and binding proteins ensures efficient iron uptake under limiting conditions.
Regulation of Ferric Iron Binding
In simple terms: Cells control the production of iron-binding proteins based on iron availability.
In bacteria, ferric iron binding proteins are regulated by iron-responsive repressors such as Fur. When iron is scarce, these repressors are inactivated, allowing expression of iron uptake genes. In Flavobacterium columnare, iron uptake systems are required for virulence and are tightly regulated. This regulation ensures iron homeostasis and prevents toxicity.
Key Genes Involved in GO:0008199 ferric iron binding
The following genes encode proteins that directly bind ferric iron or are involved in ferric iron binding-related processes.
| Gene | Major Role | Research Relevance |
|---|---|---|
| fbpA | Periplasmic ferric iron-binding protein | Model for anion-independent Fe(III) coordination |
| kfuA | Ferric iron-binding protein in Klebsiella pneumoniae | Structural analysis of ferric-binding proteins |
| fecA | TonB-dependent ferric citrate transporter | Mechanism of ferric citrate binding |
| vvuA | Ferric iron uptake in Vibrio vulnificus | Virulence and iron utilization |
| fhuA | Ferric hydroxamate uptake | Siderophore transport |
| feoB | Ferrous iron transport | Iron uptake under anaerobic conditions |
| bfr | Bacterioferritin | Iron storage |
| ftnA | Ferritin | Iron storage in bacteria |
| dps | DNA protection during starvation | Iron sequestration |
| fur | Ferric uptake regulator | Regulation of iron uptake genes |
| tonB | Energy transduction for TonB-dependent transporters | Outer membrane transport |
| exbB | TonB accessory protein | Energy transduction |
| exbD | TonB accessory protein | Energy transduction |
| hasA | Heme-binding protein | Iron acquisition from heme |
| hemO | Heme oxygenase | Heme degradation and iron release |
| sodB | Iron superoxide dismutase | Oxidative stress defense |
| bfd | Bacterioferritin-associated ferredoxin | Iron storage regulation |
How Is ferric iron binding Regulated?
Ferric iron binding activity is regulated at multiple levels. In bacteria, the Fur repressor controls transcription of iron uptake genes in response to iron availability. Additionally, siderophore production and ferrichelatase activity are induced under iron limitation. Post-translational regulation may involve proteolysis or conformational changes. In Vibrio vulnificus, the iron-utilization system is tightly regulated to balance iron acquisition and toxicity.
ferric iron binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| fbpA | Neisseria infection | Knockout in Neisseria meningitidis |
| kfuA | Klebsiella pneumoniae virulence | Mouse pneumonia model |
| fecA | E. coli iron uptake | In vitro transport assays |
| vvuA | Vibrio vulnificus infection | Mouse sepsis model |
| fur | Regulation of virulence | Reporter gene fusions |
Bacterial Virulence and Infection
Ferric iron binding proteins are essential for the virulence of many pathogens. Flavobacterium columnare requires ferric iron uptake systems for virulence in fish. Vibrio vulnificus utilizes ferric iron binding proteins to acquire iron from the host, contributing to its pathogenicity. Targeting these proteins could reduce bacterial virulence without affecting host iron metabolism.
Iron Overload and Neurodegeneration
Dysregulation of ferric iron binding can lead to iron accumulation and oxidative stress, which are implicated in neurodegenerative diseases such as Alzheimer's and Parkinson's. Although direct evidence for GO:0008199 in these diseases is limited, the role of iron-binding proteins in iron homeostasis suggests a potential link.
Antibiotic Resistance and Novel Therapeutics
Ferric iron binding proteins are attractive targets for new antibiotics because they are often surface-exposed and essential for survival. Siderophore-dependent ferrichelatases are being explored as drug targets. Inhibitors of ferric iron binding could overcome resistance mechanisms associated with conventional antibiotics.
From ferric iron binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X bind ferric iron? | Recombinant protein binding assays |
| What is the role of gene X in virulence? | Knockout in bacterial pathogen |
| How does mutation affect iron binding affinity? | Point mutation followed by ITC or SPR |
| Can we visualize ferric iron binding in cells? | Tagged knock-in with fluorescent reporter |
| Does overexpression increase iron uptake? | Overexpression in E. coli |
| Which genes are regulated by iron? | RNA-seq after iron starvation |
How to Study the ferric iron binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| X-ray crystallography | 3D structure of protein-Fe(III) complex | Determine coordination geometry |
| ITC | Binding affinity and thermodynamics | Quantify Fe(III) binding |
| SPR | Binding kinetics | Real-time interaction analysis |
| CRISPR knockout | Gene function | Virulence studies |
| RNA-seq | Transcriptional changes | Iron regulon identification |
| Fluorescence microscopy | Protein localization | Cellular imaging |
| Mass spectrometry | Protein identification and modifications | Proteomics of iron-binding proteins |
Structural Biology
X-ray crystallography and cryo-EM can determine the atomic structure of ferric iron binding proteins, revealing coordination geometry and ligand identity. These methods are essential for understanding the molecular basis of Fe(III) binding.
Biophysical Binding Assays
Isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) measure binding affinity and kinetics. These techniques can quantify the interaction between ferric iron and proteins, and assess the impact of mutations.
Genetic and Genomic Approaches
CRISPR-Cas9 knockout and knockdown can elucidate gene function in iron uptake. RNA-seq and transcriptomics reveal global regulatory networks controlled by iron availability.
Imaging and Localization
Fluorescence microscopy with tagged proteins can visualize ferric iron binding proteins in live cells. This helps determine subcellular localization and dynamics during infection.
How CRISPR Can Be Used to Study GO:0008199 ferric iron binding
Knockout
CRISPR-Cas9 knockout of ferric iron binding genes can abolish iron uptake and reduce virulence in bacterial pathogens. For example, knocking out fbpA in Neisseria or kfuA in Klebsiella pneumoniae can be used to study their roles in infection.
Point Mutation
Introducing point mutations in the iron-coordinating residues of ferric iron binding proteins can reveal their contribution to binding affinity and specificity. This approach is useful for dissecting the coordination chemistry.
Knock-in
Knock-in of tagged versions of ferric iron binding proteins (e.g., GFP or FLAG) allows visualization and purification. This can be used to study protein localization and interactions in native contexts.
Overexpression
Overexpression of ferric iron binding proteins can increase iron uptake and accumulation, which is useful for biochemical assays and for studying iron toxicity. It can also be used to produce recombinant protein for structural studies.
How EDITGENE Supports ferric iron binding Research
Researchers studying ferric iron binding-related genes often need to determine whether a candidate gene is causally involved in iron acquisition, virulence, or disease. EDITGENE provides comprehensive CRISPR services to create precise cellular and animal models for functional studies.
Contact EDITGENE today to design your custom CRISPR model for ferric iron binding research.
Frequently Asked Questions About ferric iron binding
What is ferric iron binding?
Ferric iron binding is a molecular function (GO:0008199) that enables a protein to selectively bind Fe(III), the oxidized form of iron.
What genes are involved in ferric iron binding?
Key genes include fbpA, kfuA, fecA, vvuA, and fur, which encode proteins that bind or regulate ferric iron.
How does ferric iron binding work?
Proteins coordinate Fe(III) through oxygen and nitrogen ligands, often with octahedral geometry, to achieve high affinity and specificity.
Why is ferric iron binding important for bacteria?
It is essential for iron acquisition and virulence, allowing pathogens to survive in iron-limited host environments.
What diseases are associated with ferric iron binding?
Bacterial infections and iron overload disorders; ferric iron binding proteins are virulence factors in pathogens like Vibrio vulnificus.
How can I study ferric iron binding?
Use structural biology, biophysical assays, and CRISPR knockout models to investigate protein function and regulation.
What are siderophore-dependent ferrichelatases?
Enzymes that hydrolyze siderophores to release iron for binding by ferric iron binding proteins.
Can CRISPR be used to study ferric iron binding?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models enable precise functional studies.
What is the GO term for ferric iron binding?
GO:0008199, defined as binding to a ferric iron ion, Fe(III).
How does EDITGENE support ferric iron binding research?
EDITGENE provides CRISPR cell models, library screening, and bioinformatics to study ferric iron binding genes.
Conclusion
Ferric iron binding (GO:0008199) is a fundamental molecular function with broad implications for microbial pathogenesis, iron homeostasis, and disease. Understanding its mechanisms through structural and genetic approaches can lead to new therapeutics. EDITGENE offers comprehensive CRISPR solutions to accelerate research on ferric iron binding genes.
References
- 1. Wu R et al.. 2024. The binding pattern of ferric iron and iron-binding protein in Botrytis cinerea.. Comput Biol Med 178:108686 PMID: 38850956
- 2. Merrick CE et al.. 2024. Siderophore-dependent ferrichelatases.. Methods Enzymol 702:281-315 PMID: 39155116
- 3. Tom-Yew SA et al.. 2005. Anion-independent iron coordination by the Campylobacter jejuni ferric binding protein.. J Biol Chem 280(10):9283-90 PMID: 15613474
- 4. Zhao Q et al.. 2023. Structural analysis of the ferric-binding protein KfuA from Klebsiella pneumoniae.. Biochem Biophys Res Commun 679:52-57 PMID: 37669596
- 5. Conrad RA et al.. 2022. Flavobacterium columnare ferric iron uptake systems are required for virulence.. Front Cell Infect Microbiol 12:1029833 PMID: 36325469
- 6. Nowalk AJ et al.. 1994. Coordination of iron by the ferric iron-binding protein of pathogenic Neisseria is homologous to the transferrins.. Biochemistry 33(43):12769-75 PMID: 7947682
- 7. Yue WW et al.. 2003. Structural evidence for iron-free citrate and ferric citrate binding to the TonB-dependent outer membrane transporter FecA.. J Mol Biol 332(2):353-68 PMID: 12948487
- 8. Miyamoto K et al.. 2021. Iron-Utilization System in Vibrio vulnificus M2799.. Mar Drugs 19(12) PMID: 34940709
