GO:0015675 nickel cation transport: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015675 nickel cation transport describes the directed movement of nickel (Ni) cations into, out of, or within a cell, or between cells, via transporters or pores [3,4].
• Nickel transport is essential for the function of nickel-dependent enzymes such as urease, hydrogenase, and carbon monoxide dehydrogenase, which are found in bacteria, archaea, and plants [1,2].
• Multiple transport systems exist, including secondary carriers like the NiCoT family, primary ATP-powered pumps (P1B-type ATPases), and TonB-dependent outer membrane transporters in Gram-negative bacteria [5,6].
• In plants, nickel detoxification involves vacuolar sequestration mediated by transporters such as AtIREG2, which couples iron and nickel transport.
• Dysregulation of nickel transport can lead to nickel toxicity or deficiency, impacting cellular metabolism and contributing to disease states such as cancer and neurodegeneration [4,7].
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) are powerful tools to dissect the molecular mechanisms and physiological roles of nickel transport genes [3,5].
Description
Nickel cation transport (GO:0015675) is a fundamental biological process that ensures the proper distribution of nickel ions within and between cells. Nickel is an essential micronutrient for many organisms, serving as a cofactor for enzymes involved in diverse metabolic pathways, including ureolysis, hydrogen metabolism, and carbon fixation [1,2]. The directed movement of Ni2+ across cellular membranes is mediated by specialized transport proteins that maintain nickel homeostasis and prevent toxicity. Understanding the mechanisms of nickel transport is crucial for elucidating how cells acquire this metal, how they respond to nickel limitation or excess, and how disruptions in transport contribute to disease. This article provides a comprehensive overview of nickel cation transport, integrating authoritative Gene Ontology annotations with published literature to highlight key genes, molecular mechanisms, and research methodologies. Researchers studying microbial physiology, plant nutrition, and human health will find this synthesis valuable for designing experiments and interpreting data related to nickel homeostasis [3,5,8].
nickel cation transport At A Glance
| GO ID | GO:0015675 |
|---|---|
| GO term | nickel cation transport |
| Ontology | biological_process |
| Synonym | none |
| Major function | Directed movement of nickel ions across membranes |
| Definition | The directed movement of nickel (Ni) cations into, out of or within a cell, or between cells, by means of some agent such as a transporter or pore. |
| Related transporters | NiCoT, P1B-type ATPases, TonB-dependent transporters, AtIREG2 |
| Organisms | Bacteria, archaea, plants, and potentially other eukaryotes |
What Is GO:0015675?
According to the Gene Ontology, nickel cation transport (GO:0015675) is defined as the directed movement of nickel (Ni) cations into, out of, or within a cell, or between cells, by means of some agent such as a transporter or pore. This process encompasses the translocation of Ni2+ across biological membranes, driven by various energy sources, and is essential for delivering nickel to metalloenzymes while avoiding toxic accumulation [3,4].
Why Is nickel cation transport Important in Cell Biology?
Nickel cation transport is vital for cellular physiology because nickel is a required cofactor for several key enzymes, yet free nickel ions are toxic at elevated concentrations. Transport systems tightly regulate intracellular nickel levels, ensuring adequate supply for metalloenzymes while preventing damage to proteins and DNA [1,4]. In pathogenic bacteria, nickel transport is linked to virulence factors such as urease, which is essential for survival in host environments. In plants, nickel transport affects iron homeostasis and detoxification. Moreover, disruptions in nickel transport have been implicated in human diseases, including cancer and neurodegenerative disorders, making this process a potential therapeutic target.
• Nickel is a cofactor for enzymes like urease, hydrogenase, and CO dehydrogenase, which are critical for microbial metabolism and pathogenesis [1,2].
• Transport systems prevent nickel toxicity by maintaining intracellular concentrations within a narrow range.
• Bacterial nickel transporters are essential for virulence; for example, urease-dependent pathogens require nickel uptake for survival in the host.
• In plants, nickel transport is intertwined with iron homeostasis and detoxification mechanisms.
• Dysregulated nickel transport can contribute to cancer progression and neurodegenerative diseases through metal imbalance.
• Understanding nickel transport informs biotechnology applications, such as bioremediation and bioenergy production.
• Nickel transport proteins are potential targets for antimicrobial drug development.
• Research on nickel transport sheds light on fundamental principles of metal homeostasis and membrane transport.
What Happens During nickel cation transport?
Substrate Recognition and Binding
In simple terms: The transporter first grabs nickel ions from the environment or cellular compartment.
Nickel transporters exhibit high specificity for Ni2+ over other divalent cations. For instance, the NiCoT family of secondary carriers binds nickel with high affinity, and structural studies of CorA family proteins reveal cation permeability mechanisms that discriminate among metal ions. In Gram-negative bacteria, TonB-dependent transporters at the outer membrane recognize nickel complexes and actively transport them into the periplasm using energy from the proton motive force. Plant transporters such as AtIREG2 also show specificity for nickel, although they may also transport iron.
Translocation Across the Membrane
In simple terms: The transporter moves the nickel ion across the cell membrane.
Once bound, nickel ions are translocated across the lipid bilayer through conformational changes in the transporter. Secondary carriers like NiCoT utilize the proton gradient to drive nickel uptake. Primary active transporters, such as P1B-type ATPases, hydrolyze ATP to pump nickel against its concentration gradient. In bacteria, the TonB/ExbB/ExbD complex energizes transport across the outer membrane. The CorA family proteins form pores that allow nickel permeation down electrochemical gradients.
Intracellular Distribution and Delivery
In simple terms: After entering the cell, nickel is routed to where it is needed.
Inside the cell, nickel ions are delivered to metalloenzymes or sequestered into storage compartments. In plants, AtIREG2 transports nickel into the vacuole for detoxification, a process that is iron-dependent. In bacteria, nickel is often trafficked to urease or hydrogenase via accessory proteins. The precise mechanisms of intracellular nickel trafficking are still being elucidated, but they involve metallochaperones and small molecule ligands.
Regulation of Transport Activity
In simple terms: The cell controls when and how much nickel is transported.
Nickel transport is tightly regulated at the transcriptional and post-translational levels. In bacteria, nickel-responsive regulators such as NikR control the expression of transport genes in response to nickel availability. In plants, iron deficiency can induce AtIREG2 expression, linking nickel detoxification to iron status. Post-translational regulation may involve phosphorylation or other modifications of transporters, though specific mechanisms vary by organism.
Key Genes Involved in GO:0015675 nickel cation transport
The following genes and proteins are key players in nickel cation transport across different organisms, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NiCoT | Secondary nickel transporter in bacteria | Model for proton-coupled metal transport |
| CorA | Magnesium and nickel transporter in bacteria | Studied for cation selectivity and permeability |
| TonB | Energizes outer membrane transport in Gram-negative bacteria | Essential for nickel uptake and virulence |
| ExbB | Component of TonB complex | Assists in energy transduction for nickel transport |
| ExbD | Component of TonB complex | Assists in energy transduction for nickel transport |
| P1B-type ATPases | ATP-powered nickel efflux pumps | Involved in nickel resistance and homeostasis |
| AtIREG2 | Tonoplast nickel transporter in Arabidopsis | Links iron and nickel detoxification |
| NikR | Nickel-responsive transcriptional regulator | Controls nickel transport gene expression |
| Urease | Nickel-dependent enzyme | Requires nickel transport for activity and virulence |
| Hydrogenase | Nickel-dependent enzyme | Requires nickel for hydrogen metabolism |
| CO dehydrogenase | Nickel-dependent enzyme | Requires nickel for carbon monoxide oxidation |
| CbiN | Cobalt/nickel transport protein | Involved in metal uptake for coenzyme B12 synthesis |
| CbiM | Cobalt/nickel transport protein | Involved in metal uptake for coenzyme B12 synthesis |
| CbiQ | Cobalt/nickel transport protein | Involved in metal uptake for coenzyme B12 synthesis |
| NixA | High-affinity nickel transporter in Helicobacter pylori | Critical for urease activity and colonization |
| HoxN | Nickel transporter in bacteria | Studied for nickel uptake in hydrogenase maturation |
| Nic1 | Nickel transporter in fungi | Potential model for eukaryotic nickel transport |
How Is nickel cation transport Regulated?
Nickel cation transport is regulated at multiple levels to maintain metal homeostasis. In bacteria, the NikR regulator senses intracellular nickel and modulates the expression of nickel uptake and efflux genes. In plants, iron deficiency induces the expression of AtIREG2, which transports nickel into vacuoles, indicating cross-talk between iron and nickel homeostasis. Additionally, the activity of P1B-type ATPases can be regulated by metal-responsive transcription factors and post-translational modifications. These regulatory mechanisms ensure that nickel levels are sufficient for metalloenzyme function without reaching toxic concentrations.
nickel cation transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NixA | Helicobacter pylori infection | Knockout in H. pylori; mouse colonization model |
| Urease | Gastric ulcer and cancer | Point mutation to abolish nickel binding; infection studies |
| AtIREG2 | Nickel toxicity in plants | Knockout in Arabidopsis; growth on nickel-amended media |
| P1B-type ATPases | Nickel resistance in bacteria | Overexpression and knockout in E. coli; metal sensitivity assays |
| NiCoT | Nickel homeostasis in bacteria | Knockout and complementation; transport assays |
Nickel Transport in Bacterial Pathogenesis
In pathogenic bacteria such as Helicobacter pylori, nickel transport is essential for the activity of urease, which neutralizes stomach acid and enables colonization. Disruption of nickel transporters like NixA reduces urease activity and attenuates virulence, making these proteins attractive antimicrobial targets. Similarly, in other pathogens, nickel uptake systems are required for the maturation of hydrogenases and other virulence-associated enzymes.
Nickel Toxicity and Cancer
Excessive nickel exposure is associated with increased risk of lung and nasal cancers. Nickel ions can interfere with DNA repair and induce oxidative stress. Dysregulated nickel transport may contribute to cellular nickel accumulation and carcinogenesis. Understanding how nickel transporters are altered in cancer cells could reveal new therapeutic strategies.
Neurodegeneration and Metal Imbalance
Nickel has been implicated in neurodegenerative processes, although its role is less understood than that of copper or iron. Disruption of metal transport, including nickel, may contribute to protein aggregation and neuronal death. Further research is needed to clarify the specific contributions of nickel transport to diseases like Alzheimer's and Parkinson's.
Plant Nickel Detoxification and Agriculture
In plants, nickel toxicity can occur in serpentine soils, and transporters like AtIREG2 mediate vacuolar sequestration to mitigate damage. Crops engineered for improved nickel tolerance could benefit from modulating such transporters, linking nickel transport research to agricultural biotechnology.
From nickel cation transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of nickel transporter knockout on bacterial virulence? | Knockout of NixA in H. pylori; mouse infection model |
| How does a point mutation in the nickel-binding site affect transport activity? | Point mutation in NiCoT or CorA; in vitro transport assays |
| Can a tagged nickel transporter be used to study localization? | Knock-in of GFP tag into endogenous locus; fluorescence microscopy |
| What is the impact of nickel transporter overexpression on metal tolerance? | Overexpression of P1B-type ATPase in E. coli; MIC assays |
| How does nickel transport affect plant growth under iron deficiency? | Knockout of AtIREG2 in Arabidopsis; growth on iron-deficient media |
| What are the transcriptional changes upon nickel exposure? | RNA-seq of wild-type and transporter mutants |
How to Study the nickel cation transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| 63Ni uptake assay | Transport activity and kinetics | Characterizing nickel transporters in bacteria |
| Knockout and complementation | Gene essentiality and function | Determining roles of NiCoT, CorA, AtIREG2 [3,8] |
| RNA-seq | Transcriptional response to nickel | Identifying nickel-regulated genes |
| Proteomics | Protein expression changes | Assessing nickel-dependent enzyme levels |
| Fluorescence microscopy | Subcellular localization | Tagged transporters in live cells |
| ATPase assay | ATP hydrolysis by P1B-type ATPases | Measuring pump activity |
| Metal sensitivity assays | Growth inhibition by nickel | Testing transporter mutants |
| Isothermal titration calorimetry | Binding affinity for nickel | Studying metal-protein interactions |
Transport Assays with Radioactive Nickel
Radioactive nickel (63Ni) uptake assays are a classic method to measure transport activity in bacteria, plants, and cell lines. Cells are incubated with 63NiCl2, and intracellular accumulation is quantified by scintillation counting. This method can determine kinetic parameters (Km, Vmax) and specificity of transporters.
Genetic Knockouts and Complementation
Knockout mutants of nickel transporter genes are generated to assess their physiological roles. Complementation with wild-type or mutant alleles restores function and allows structure-function studies. This approach has been used to characterize NiCoT, CorA, and AtIREG2 [3,8].
Transcriptomics and Proteomics
RNA-seq and proteomics can reveal global changes in gene expression in response to nickel availability or transporter mutations. For example, nickel-responsive regulons can be identified by comparing wild-type and mutant strains under nickel-replete and nickel-limited conditions.
Structural Biology and Imaging
Crystal structures of nickel transporters such as CorA provide insights into cation selectivity and gating mechanisms. Fluorescently tagged transporters enable live-cell imaging of localization and dynamics, often using knock-in approaches.
How CRISPR Can Be Used to Study GO:0015675 nickel cation transport
Knockout
CRISPR-Cas9 knockout of nickel transporter genes (e.g., NixA, NiCoT, AtIREG2) enables loss-of-function studies to determine their roles in nickel uptake, virulence, and metal tolerance. Knockout cell lines or organisms can be generated by inducing frameshift mutations in early exons, followed by validation of protein absence and phenotypic analysis [3,6,8].
Point Mutation
CRISPR-mediated point mutations can introduce specific amino acid substitutions in nickel transporters to dissect metal-binding sites, proton-coupled transport mechanisms, or regulatory phosphorylation sites. For example, mutating conserved residues in CorA or NiCoT can reveal their roles in cation selectivity and transport [3,5].
Knock-in
Knock-in of epitope tags (e.g., GFP, FLAG) or reporter genes into endogenous nickel transporter loci allows real-time visualization and quantification of protein expression and localization. This approach is valuable for studying transporter dynamics under different nickel conditions.
Overexpression
CRISPR activation (CRISPRa) or transgenic overexpression of nickel transporters can be used to study gain-of-function phenotypes, such as increased nickel uptake, enhanced metalloenzyme activity, or altered metal sensitivity. Overexpression models are also useful for structural and biochemical studies requiring large amounts of protein [5,8].
How EDITGENE Supports nickel cation transport Research
Researchers studying nickel cation transport-related genes often need to determine whether a candidate gene is causally involved in nickel homeostasis, metal tolerance, or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this research, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for nickel cation transport research.
Frequently Asked Questions About nickel cation transport
What is nickel cation transport?
Nickel cation transport (GO:0015675) is the directed movement of nickel ions into, out of, or within a cell, or between cells, mediated by transporters or pores [3,4].
What genes are involved in nickel cation transport?
Key genes include NiCoT, CorA, TonB, ExbB, ExbD, P1B-type ATPases, AtIREG2, NixA, and HoxN, among others [2,3,5,6,8].
Why is nickel transport important for bacteria?
Nickel transport is essential for supplying nickel to enzymes like urease and hydrogenase, which are critical for bacterial metabolism and virulence [1,6].
How is nickel transport regulated?
Nickel transport is regulated by metal-responsive transcription factors such as NikR in bacteria and by iron status in plants via AtIREG2 [4,8].
What diseases are associated with nickel transport?
Disruptions in nickel transport are linked to bacterial infections, nickel toxicity, cancer, and potentially neurodegenerative diseases [6,7].
What methods are used to study nickel transport?
Common methods include radioactive nickel uptake assays, knockout/complementation, RNA-seq, proteomics, and structural biology [2,3,4,5].
Can CRISPR be used to study nickel transport genes?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are powerful tools to dissect nickel transport mechanisms [3,5,8].
What is the role of AtIREG2 in nickel transport?
AtIREG2 is a tonoplast transporter in Arabidopsis that mediates iron-dependent nickel detoxification by sequestering nickel into vacuoles.
How does nickel enter Gram-negative bacteria?
Nickel is transported across the outer membrane by TonB-dependent transporters energized by the TonB/ExbB/ExbD complex.
What are P1B-type ATPases?
P1B-type ATPases are primary active transporters that pump nickel and other metals across membranes using ATP hydrolysis.
Conclusion
Nickel cation transport (GO:0015675) is a critical biological process that ensures the proper distribution of nickel for metalloenzyme function while preventing toxicity. Research across bacteria, plants, and human cells has revealed diverse transport systems and regulatory mechanisms. Understanding these processes has implications for infectious diseases, cancer, and biotechnology. With advanced CRISPR tools and multi-omics approaches, the field is well-positioned to uncover new therapeutic targets and biotechnological applications [1,3,4,5,6,7,8].
References
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- 3. Stetsenko A et al.. 2020. Cation permeability in CorA family of proteins.. Sci Rep 10(1):840 PMID: 31965019
- 4. Nies DH et al.. 2009. Transition Metal Homeostasis.. EcoSal Plus 3(2) PMID: 26443772
- 5. Smith AT et al.. 2014. Diversity of the metal-transporting P1B-type ATPases.. J Biol Inorg Chem 19(6):947-60 PMID: 24729073
- 6. Schauer K et al.. 2007. Novel nickel transport mechanism across the bacterial outer membrane energized by the TonB/ExbB/ExbD machinery.. Mol Microbiol 63(4):1054-68 PMID: 17238922
- 7. Nickel S et al.. 2016. Transport mechanisms at the pulmonary mucosa: implications for drug delivery.. Expert Opin Drug Deliv 13(5):667-90 PMID: 26909544
- 8. Schaaf G et al.. 2006. AtIREG2 encodes a tonoplast transport protein involved in iron-dependent nickel detoxification in Arabidopsis thaliana roots.. J Biol Chem 281(35):25532-40 PMID: 16790430
