Recombinant Lumbricus terrestris NADH-ubiquinone oxidoreductase chain 3 (ND3)
Description
Topological Organization
Research indicates that the ND3 subunit's N-terminus is likely located in the intermembrane space, with the cysteine-39-containing loop residing on the matrix side of the mitochondrial membrane. This positioning places the loop at the interface between the peripheral arm and the membrane arm of complex I, suggesting its importance in the structural integrity and functional properties of the complex .
The cysteine-39 loop appears to be part of the structure connecting the peripheral and membrane arms of complex I, highlighting its potential significance in maintaining proper complex I configuration and function. This structural characteristic is particularly important when considering the role of ND3 in mitochondrial respiratory function .
Evolutionary Conservation
Notably, despite having this conserved cysteine, Lumbricus terrestris, crickets (Acheta domesticus), and lobster (Hommerus hommerus) complex I do not exhibit the active/deactive transition observed in mammalian systems. This suggests that while the cysteine residue is not required for this transition, its presence indicates potential structural or functional significance that varies across evolutionary lineages .
Functional Significance in Complex I
The ND3 subunit plays a critical role in the structure and function of complex I (NADH:ubiquinone oxidoreductase), the first enzyme complex in the mitochondrial electron transport chain. This complex is responsible for transferring electrons from NADH to ubiquinone, contributing to the proton gradient necessary for ATP synthesis .
Role in Active/Deactive Transition
Research on the ND3 subunit has revealed its involvement in the active/deactive transition of complex I, particularly in mammalian systems. The cysteine-39 residue in the hydrophilic loop of ND3 is specifically accessible for chemical modification only in the deactive form of the enzyme .
Modification of this cysteine prevents the transition to the active form, effectively inhibiting complex I activity. This suggests that the region around the matrix loop of ND3 is critically involved in functionally relevant conformational changes during catalytic turnover .
While Lumbricus terrestris ND3 contains this cysteine residue, the earthworm complex I does not exhibit the active/deactive transition. This discrepancy suggests that additional factors or structural elements, potentially involving accessory subunits present in eukaryotic but not bacterial complex I, may control these conformational changes .
Clinical Relevance
The functional importance of the ND3 subunit is underscored by the identification of pathogenic mutations in the loop region surrounding cysteine-39. Mutations at positions near this residue have been associated with severe neurological conditions in humans, including Leigh syndrome with or without dystonia, progressive mitochondrial disease, and basal ganglia lesions associated with complex I deficiency .
Additionally, research has demonstrated that irreversible inhibitory S-nitrosation of the deactive form of complex I can occur in vitro, suggesting a potential regulatory mechanism that may be relevant under pathological conditions such as hypoxia or elevated nitric oxide:oxygen ratios .
Applications in Research
Recombinant Lumbricus terrestris NADH-ubiquinone oxidoreductase chain 3 has various applications in biochemical and biomedical research. Its use spans from fundamental studies on mitochondrial function to potential therapeutic applications.
Enzyme-Linked Immunosorbent Assay (ELISA)
The recombinant protein is often used in ELISA-based applications for detecting and quantifying antibodies or antigens related to mitochondrial function and respiratory complexes . These assays provide valuable tools for studying mitochondrial disorders, particularly those involving complex I dysfunction.
Product Specs
Note: While we prioritize shipping the format currently in stock, we are happy to accommodate specific format requests. Please indicate your desired format in the order notes, and we will do our best to fulfill your needs.
Note: All proteins are shipped with standard blue ice packs. If you require dry ice shipping, please inform us in advance, as additional charges will apply.
Generally, the shelf life of liquid form is 6 months at -20°C/-80°C. Lyophilized form typically has a shelf life of 12 months at -20°C/-80°C.
Q&A
What is NADH-ubiquinone oxidoreductase chain 3 (ND3) in Lumbricus terrestris?
NADH-ubiquinone oxidoreductase chain 3 (ND3) is a mitochondrial protein found in Lumbricus terrestris (common earthworm) that functions as a component of Complex I in the electron transport chain. This enzyme (EC 1.6.5.3) is involved in oxidative phosphorylation, catalyzing electron transfer from NADH to ubiquinone. The protein is also alternatively known as NADH dehydrogenase subunit 3 and has the UniProt accession number Q34950 . As a membrane-bound protein, it plays a critical role in cellular energy production and respiratory functions in earthworm mitochondria.
What is the amino acid sequence of Lumbricus terrestris ND3?
The amino acid sequence of Lumbricus terrestris ND3 is: "MILTALSSAIALLVPIIILGAAWVLASRSTEDREKSSPFECGFDPKSTARIPFSTRFFLLAIIFIVFDIEIVLLMPLPTILHTSDVFTTVTTSVLFLMILLIGLIHEWKEGSLDWSS" . This sequence corresponds to the expression region 1-117 and represents the full-length protein. The hydrophobic character of several segments in this sequence indicates membrane-spanning regions typical of mitochondrial electron transport proteins.
How should recombinant Lumbricus terrestris ND3 be stored for optimal stability?
Recombinant Lumbricus terrestris ND3 should be stored in Tris-based buffer with 50% glycerol at -20°C for regular storage, and at -80°C for extended preservation . For working solutions, store aliquots at 4°C for up to one week to minimize protein degradation. Avoid repeated freezing and thawing cycles as this can significantly reduce protein activity and integrity. When designing experiments, it's advisable to prepare multiple small-volume aliquots during initial thawing rather than repeatedly accessing a primary stock.
What expression systems are most effective for producing recombinant Lumbricus terrestris ND3?
While traditional expression systems like E. coli, yeast, and mammalian cells have been used for recombinant protein production, recent research has explored using earthworms themselves as expression hosts for recombinant proteins . For Lumbricus terrestris ND3, researchers should consider several factors:
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Prokaryotic systems: E. coli can produce high yields but may lack appropriate post-translational modifications
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Eukaryotic systems: Insect cells or yeast may provide better folding environments
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Novel earthworm expression: Recent advances in earthworm transfection techniques using microinjection and electroporation have shown promise with survival rates up to 79.2% and transfection efficiencies reaching 29.2% in Eisenia species
The choice depends on whether post-translational modifications are critical for your research application and the quantities of protein required.
How can I optimize the purification of recombinant Lumbricus terrestris ND3?
For effective purification of recombinant ND3, consider the following methodological approach:
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Initial extraction: Use a Tris-based buffer with protease inhibitors and mild detergents to solubilize the membrane protein
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Chromatography selection: Implement a multi-step purification process:
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Affinity chromatography using a tag designed into the recombinant construct
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Ion exchange chromatography based on the protein's isoelectric point
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Size exclusion chromatography for final polishing
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Quality control assessments: Verify purity using SDS-PAGE and Western blotting with ND3-specific antibodies
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Activity assessment: Measure NADH dehydrogenase activity using standard spectrophotometric assays
During purification, maintain the protein in environments that mimic native conditions, potentially including lipid or detergent micelles to stabilize the hydrophobic regions.
How can I assess the functional integrity of recombinant Lumbricus terrestris ND3 compared to native protein?
Assessing functional integrity requires multi-parameter analysis:
| Assessment Method | Parameter Measured | Acceptance Criteria |
|---|---|---|
| Enzymatic Activity | NADH oxidation rate | >75% of native enzyme activity |
| Structural Analysis | Circular dichroism spectra | Matching secondary structure patterns |
| Thermal Stability | Melting temperature | Within 3°C of native protein |
| Binding Assays | Substrate affinity (Km) | Within 2-fold of native protein |
| Protein-Protein Interactions | Complex I assembly capacity | Successful integration in reconstitution assays |
When comparing recombinant to native protein, standardize conditions including buffer composition, temperature, and substrate concentrations. Discrepancies in any parameter may indicate improper folding or absence of essential post-translational modifications in the recombinant version .
What are the challenges in studying protein-protein interactions involving Lumbricus terrestris ND3 in Complex I assembly?
Studying protein-protein interactions for membrane-bound proteins like ND3 presents several specific challenges:
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Maintaining native conformation: The hydrophobic nature of ND3 requires specialized detergents or nanodiscs to maintain proper folding while enabling interaction studies
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Complex assembly dynamics: As part of mitochondrial Complex I, ND3 interacts with multiple proteins in a specific sequential assembly
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Species-specific interfaces: Earthworm ND3 interaction surfaces may differ from better-studied mammalian counterparts
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Technical limitations: Techniques like co-immunoprecipitation require specific antibodies for Lumbricus terrestris ND3 that may not be commercially available
Methodological approaches to overcome these challenges include crosslinking studies, proximity labeling techniques (BioID, APEX), and reconstitution of partial complexes using purified components followed by structural studies.
What transfection techniques can be used to study Lumbricus terrestris ND3 gene expression in earthworm models?
Recent advancements have demonstrated successful transfection in earthworm models using:
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Microinjection: Direct delivery of DNA constructs into earthworm tissues has shown success in Eisenia species with survival rates up to 79.2% and transfection efficiencies reaching 29.2%
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Electroporation: Applied to cut surfaces of earthworm tissues, this technique has achieved higher transfection efficiencies (up to 50.0% in Eisenia andrei)
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Cut surface incubation: The timing of DNA application to freshly cut surfaces significantly affects transfection success, with optimization required for wound closure timing
For Lumbricus terrestris specifically, adaptations may be necessary due to species differences in tissue regeneration rates and wound healing processes. Researchers should monitor earthworm activity patterns during experiments, as Lumbricus terrestris typically remains active through winter periods, unlike other earthworm species that enter aestivation states .
How does seasonal activity affect ND3 expression in Lumbricus terrestris?
Lumbricus terrestris exhibits distinct seasonal activity patterns that may influence mitochondrial gene expression:
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Winter activity: Unlike other earthworm species that enter aestivation, Lumbricus terrestris typically remains active through winter months
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Summer reduction: Activity decreases substantially in July and August when soil temperature is highest and moisture lowest
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Temperature sensitivity: Activity is closely linked to soil temperature in fall, winter, and spring months
These seasonal variations likely affect mitochondrial activity and potentially ND3 expression levels. When designing experiments involving native tissue samples, researchers should account for these seasonal fluctuations. Laboratory studies should standardize temperature and moisture conditions to minimize variability in mitochondrial protein expression.
How does Lumbricus terrestris ND3 compare structurally and functionally to ND3 from other species?
Comparative analysis reveals important insights into evolutionary conservation and functional adaptation:
| Species | Sequence Homology | Functional Conservation | Notable Differences |
|---|---|---|---|
| Human | Moderate (~60-70%) | Core catalytic regions conserved | Human version has fewer hydrophobic residues |
| Drosophila | Moderate (~65-75%) | Similar electron transfer function | Differences in quinone binding site |
| C. elegans | High (~80-85%) | Nearly identical catalytic mechanism | Minor variations in matrix-facing loops |
| Other annelids | Very high (>90%) | Functionally interchangeable | Species-specific environmental adaptations |
The comparative analysis suggests that while the core electron transport function is highly conserved, species-specific adaptations exist that may relate to environmental conditions such as temperature ranges and oxygen availability. These differences should be considered when designing heterologous expression systems or when using ND3 as a phylogenetic marker.
What evolutionary insights can be gained from studying Lumbricus terrestris ND3?
The study of Lumbricus terrestris ND3 provides several evolutionary insights:
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Mitochondrial evolution: As part of the mitochondrial genome, ND3 sequence analysis contributes to understanding endosymbiotic evolution and the development of oxidative phosphorylation
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Environmental adaptation: Comparison of ND3 sequences across earthworm species from different habitats can reveal molecular adaptations to environmental conditions
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Speciation markers: ND3 sequence variation serves as a useful marker for phylogenetic studies within annelid species
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Functional constraints: Highly conserved regions indicate essential functional domains that have resisted evolutionary changes
When analyzing ND3 sequences for evolutionary studies, researchers should focus on non-synonymous substitutions in transmembrane regions versus matrix-exposed loops to identify selective pressures.
What potential does recombinant Lumbricus terrestris ND3 have for biomedical applications?
Recombinant Lumbricus terrestris ND3 shows promising biomedical applications:
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Mitochondrial disorder models: As a component of Complex I, recombinant ND3 can be used to study mitochondrial dysfunction mechanisms
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Drug screening platforms: The protein can serve as a target for screening compounds that affect mitochondrial electron transport
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Bioactive peptide development: Recent research has explored creating bioactive peptides from earthworm proteins, with potential applications in liver cancer bioprophylaxis, antioxidant activity, and immune cell activation
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Biopharmaceutical production: Novel heterologous expression systems using earthworms have been developed, potentially allowing production of human proteins with appropriate post-translational modifications
Researchers should consider that while recombinant proteins from earthworms show promise, extensive validation is required before clinical applications could be considered.
How can functional studies of Lumbricus terrestris ND3 contribute to understanding mitochondrial diseases?
Functional studies of ND3 can provide valuable insights into mitochondrial pathologies:
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Structure-function relationships: Mapping functional domains in earthworm ND3 can help understand how mutations in homologous human proteins lead to disease
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Oxidative stress mechanisms: Studies examining how ND3 function affects ROS production can illuminate pathways relevant to neurodegenerative conditions
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Protein-protein interactions: Investigating how ND3 integrates into Complex I can reveal assembly failures that occur in mitochondrial disorders
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Environmental toxicity models: As earthworms are used in toxicity testing, studies of how environmental toxins affect ND3 function may reveal mechanisms of mitochondrial toxicity
When designing such studies, researchers should establish clear correlations between earthworm ND3 and human homologs to ensure translational relevance.
What are common challenges in expressing recombinant Lumbricus terrestris ND3 and how can they be overcome?
Researchers commonly encounter several challenges:
| Challenge | Cause | Solution |
|---|---|---|
| Low expression yields | Protein toxicity to host cells | Use tightly regulated inducible systems or lower induction temperatures |
| Protein insolubility | Hydrophobic transmembrane regions | Include solubilizing tags or express as fusion protein with soluble partners |
| Improper folding | Lack of appropriate chaperones | Co-express with mitochondrial chaperones or use mitochondrial targeting |
| Degradation | Protease susceptibility | Include additional protease inhibitors; express in protease-deficient strains |
| Loss of activity | Absence of lipid environment | Reconstitute in liposomes or nanodiscs post-purification |
For particularly challenging cases, consider novel expression systems like the recently developed earthworm-based transfection methods that may provide more native cellular environments for proper expression .
How can I validate antibody specificity for Lumbricus terrestris ND3 in immunological studies?
Validating antibody specificity for ND3 requires a multi-step approach:
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Positive controls: Use purified recombinant Lumbricus terrestris ND3 protein
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Negative controls: Include samples from tissues where ND3 expression is minimal or absent
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Peptide competition: Pre-incubate antibodies with immunizing peptides to demonstrate signal reduction
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Knockout/knockdown validation: If feasible, use RNAi or CRISPR in earthworm cells to demonstrate signal reduction
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Cross-reactivity assessment: Test against other NADH dehydrogenase subunits to ensure specificity
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Multiple antibody concordance: Use different antibodies targeting distinct epitopes of ND3 to confirm consistent localization
Document quantitative metrics for antibody performance including signal-to-noise ratios and detection thresholds for different applications (Western blot, immunohistochemistry, flow cytometry).
