Recombinant Lachesis muta muta NADH-ubiquinone oxidoreductase chain 4 (MT-ND4)
Description
Introduction to Recombinant Lachesis muta muta NADH-ubiquinone oxidoreductase chain 4 (MT-ND4)
Recombinant Lachesis muta muta NADH-ubiquinone oxidoreductase chain 4 (MT-ND4) is a protein derived from the bushmaster snake (Lachesis muta muta), one of the largest venomous snakes in the Americas. This protein is a recombinantly produced version of a mitochondrial protein that serves as a critical component of the respiratory chain Complex I. MT-ND4 belongs to a family of proteins encoded by the mitochondrial genome and represents one of the core subunits of NADH dehydrogenase (ubiquinone) . The gene is identified under several names including MT-ND4, MTND4, NADH4, and ND4, indicating its conservation and importance across different taxonomic classifications .
The recombinant production of this protein enables researchers to study its structure, function, and potential applications in various fields including biochemistry, molecular biology, and pharmaceutical development. The availability of purified recombinant MT-ND4 allows for detailed investigation of its properties without the need for direct extraction from animal tissues, which presents both ethical and practical advantages . Additionally, recombinant technology permits controlled modifications to the protein structure, facilitating studies on structure-function relationships.
MT-ND4's significance extends beyond basic research, as mutations in this gene have been associated with several human pathologies, making it a valuable target for understanding mitochondrial disease mechanisms and potentially developing therapeutic approaches . The protein's role in energy metabolism positions it at the center of cellular bioenergetics, a fundamental aspect of all living organisms.
Function in Mitochondrial Respiration
MT-ND4 serves as a critical subunit of respiratory chain Complex I (NADH dehydrogenase), which is the largest of the five complexes in the electron transport chain . Complex I initiates the electron transport process by accepting electrons from NADH and transferring them to ubiquinone (coenzyme Q10). This process is fundamental to cellular respiration and ATP production in eukaryotic cells.
The functional mechanism begins when NADH binds to Complex I and transfers two electrons to the flavin mononucleotide (FMN) prosthetic group, forming FMNH2 . These electrons are subsequently passed through a series of iron-sulfur (Fe-S) clusters within the complex, ultimately reaching coenzyme Q10, which is reduced to ubiquinol (CoQH2) . This electron transfer triggers conformational changes in the protein structure, resulting in the pumping of four hydrogen ions from the mitochondrial matrix to the intermembrane space, contributing to the proton gradient that drives ATP synthesis .
The MT-ND4 subunit is believed to be part of the minimal assembly of core proteins required for NADH dehydrogenation and electron transfer to ubiquinone . Its location within the transmembrane domain of Complex I positions it ideally to participate in the proton-pumping mechanism. The highly conserved nature of this protein across species underscores its essential role in mitochondrial function.
Production and Purification Methods
Recombinant Lachesis muta muta MT-ND4 is produced using various expression systems, each offering distinct advantages depending on the intended application. The primary expression hosts include Escherichia coli, yeast, baculovirus-infected insect cells, and mammalian cells . Each system has its own benefits: E. coli provides high yield and cost-effectiveness, yeast offers eukaryotic post-translational modifications, baculovirus systems provide high-level expression of complex proteins, and mammalian cells ensure the most native-like modifications.
The production process typically begins with the cloning of the MT-ND4 gene into an appropriate expression vector. For the recombinant Lachesis muta muta MT-ND4, the gene sequence is optimized for expression in the chosen host system while maintaining the functional regions of the protein. In some cases, affinity tags such as His-tags may be incorporated to facilitate purification, as seen in related recombinant proteins like the Canis lupus MT-ND4L .
Following expression, the protein undergoes a series of purification steps designed to achieve a purity of at least 85%, as determined by SDS-PAGE analysis . These steps may include various chromatographic techniques such as affinity chromatography, ion exchange chromatography, and size exclusion chromatography. The specific purification strategy depends on the expression system used and the presence of any affinity tags.
The final product is typically available in different formulations, including lyophilized powder or protein in buffer solution, with recommendations for storage and handling to maintain protein stability and activity . For instance, it is generally advised to avoid repeated freeze-thaw cycles and to store working aliquots at appropriate temperatures, typically 4°C for short-term storage and -20°C/-80°C for long-term storage .
| Production Aspect | Details |
|---|---|
| Expression Systems | E. coli, Yeast, Baculovirus, Mammalian Cells |
| Purification Methods | Chromatography (affinity, ion exchange, size exclusion) |
| Final Purity | ≥85% by SDS-PAGE |
| Storage Recommendations | Short-term: 4°C; Long-term: -20°C/-80°C |
| Available Formulations | Lyophilized powder, buffer solution |
Clinical and Research Applications
Recombinant Lachesis muta muta MT-ND4 serves as a valuable tool for numerous clinical and research applications. As a component of the mitochondrial respiratory chain, it provides researchers with opportunities to study mitochondrial function, bioenergetics, and the molecular mechanisms underlying various mitochondrial disorders. The availability of purified recombinant protein facilitates in vitro studies that would otherwise be challenging due to the complexity of isolating native mitochondrial proteins.
In the field of biochemistry, this recombinant protein enables detailed investigations of electron transport mechanisms and structural studies of Complex I. Researchers can use it to examine protein-protein interactions within the respiratory complex, providing insights into how these large multiprotein assemblies function cohesively. Additionally, the protein serves as a substrate for developing and testing assays to measure Complex I activity, which is essential for diagnosing mitochondrial disorders .
For pharmaceutical research, recombinant MT-ND4 offers opportunities to screen potential drug compounds that might affect mitochondrial function. Since mitochondrial dysfunction is implicated in numerous diseases, including neurodegenerative disorders, diabetes, and cancer, compounds that modulate Complex I activity could have significant therapeutic potential. The availability of purified recombinant protein facilitates high-throughput screening approaches to identify such compounds .
In genetic research, the recombinant protein provides a reference for studying the effects of known disease-associated mutations. By comparing the activity and structure of wild-type MT-ND4 with mutated versions, researchers can better understand how genetic variations lead to functional impairments and clinical manifestations. This knowledge is crucial for developing targeted therapeutic approaches for mitochondrial disorders .
Associated Pathologies and Mutations
Mutations in the MT-ND4 gene have been associated with several significant human pathologies, highlighting the clinical importance of this protein. Leber's hereditary optic neuropathy (LHON) is strongly linked to MT-ND4 mutations, particularly a mutation at codon 340 that converts a highly conserved arginine to histidine . This mutation eliminates an Sfa NI restriction site, providing a diagnostic marker for the disease, which is characterized by optic nerve degeneration and cardiac dysrhythmia .
Age-related macular degeneration (AMD) has also been associated with MT-ND4 variations. Specifically, the mt12007 single-nucleotide polymorphism (SNP) in MT-ND4 is one of five mitochondrial SNPs linked to AMD in Mexican Americans . This connection underscores the potential role of mitochondrial dysfunction in the development of age-related diseases affecting the retina.
Research has revealed a significant correlation between MT-ND4 mutations and mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis. The 11994 C>T mutation in the MT-ND4 gene results in a threonine to isoleucine substitution at position 412, which appears to contribute to the pathogenesis of this form of epilepsy . This finding suggests potential diagnostic applications for MT-ND4 gene analysis in MTLE cases.
Additionally, MT-ND4 expression is downregulated in cystic fibrosis, a disease resulting from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) channel. Studies suggest that MT-ND4 expression is indirectly regulated by CFTR chloride transport activity, indicating a complex relationship between ion transport and mitochondrial function .
| Pathology | Associated MT-ND4 Mutation | Clinical Features |
|---|---|---|
| Leber's hereditary optic neuropathy (LHON) | Codon 340: Arg to His | Optic nerve degeneration, cardiac dysrhythmia |
| Age-related macular degeneration (AMD) | mt12007 SNP | Progressive retinal degeneration |
| Mesial temporal lobe epilepsy (MTLE) | 11994 C>T (Thr412Ile) | Seizures, hippocampal sclerosis |
| Cystic fibrosis | Downregulation (secondary effect) | Multiple system involvement due to CFTR dysfunction |
Future Research Directions
The field of mitochondrial research, particularly concerning MT-ND4 and Complex I, continues to evolve, presenting numerous opportunities for future investigations. One promising direction involves the development of more sophisticated recombinant expression systems to produce MT-ND4 with post-translational modifications that more closely resemble those found in the native protein. Such advances would enhance the utility of recombinant MT-ND4 for structural studies and functional assays.
Gene therapy approaches targeting MT-ND4 mutations represent another exciting frontier in research. Given the established connection between MT-ND4 mutations and conditions like LHON, developing methods to deliver functional copies of the gene to affected tissues could provide therapeutic benefits. This approach is particularly relevant for mitochondrial diseases, which currently have limited treatment options .
Cross-species comparative studies of MT-ND4 from various organisms, including Lachesis muta muta, could yield insights into the evolutionary conservation of this protein and identify species-specific adaptations that might inform our understanding of human mitochondrial function. Such studies might reveal structural features that contribute to resistance to certain pathological conditions or enhanced efficiency in electron transport.
Lastly, the development of animal models with specific MT-ND4 mutations would greatly facilitate in vivo studies of mitochondrial dysfunction. While work has been done with related proteins like NDUFS4, creating models specifically targeting MT-ND4 would provide valuable tools for testing potential therapeutics and understanding disease progression .
Product Specs
Note: While we prioritize shipping the format currently in stock, we can accommodate specific format requirements. Please indicate your preference in the order notes, and we will fulfill your request whenever possible.
Note: All proteins are shipped with standard blue ice packs. If dry ice shipment is required, please inform us in advance, as additional fees 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.
Target Background
Q&A
What is the mitochondrial genomic organization of Lachesis muta muta MT-ND4?
The MT-ND4 gene in Lachesis muta muta is encoded on the heavy strand of the mitochondrial genome. According to mitogenome analysis, the ND4 gene in Lachesis has a length of 1,114 bp, uses ATG as a start codon, and is positioned between tRNA-His and tRNA-Ser in the mitochondrial genome. The complete mitogenome organization shows unique structural characteristics compared to other snake families, with control regions positioned differently than in other vertebrates .
How does the MT-ND4 protein function within mitochondrial complex I?
MT-ND4 serves as an essential subunit of NADH-ubiquinone oxidoreductase (complex I) in the mitochondrial respiratory chain. It plays a crucial role in the electron transport chain and oxidative phosphorylation processes. The protein participates in proton pumping across the inner mitochondrial membrane, contributing to ATP production. Functional studies show that proper MT-ND4 expression and localization to mitochondria are critical for maintaining ATP production through oxidative phosphorylation and for preserving cellular respiratory capacity .
What expression systems are most effective for producing recombinant MT-ND4?
For expression of recombinant MT-ND4, AAV2-based vector systems have demonstrated significant efficacy. Specifically, constructing a recombinant AAV2-based therapeutic vector with a codon-optimized human ND4 protein incorporating a mitochondrial targeting sequence has shown promising results. Following transduction, proper cellular localization can be verified through mitochondria/cytosol fractionation and western blot analysis. Expression efficiency can be evaluated by measuring ATP production and oxygen consumption rates in target cells .
How can researchers evaluate the mitochondrial localization and functional integration of recombinant MT-ND4?
A multi-step verification process is recommended:
-
Subcellular fractionation: Perform mitochondria/cytosol fractionation following transduction with the recombinant construct.
-
Western blot analysis: Confirm protein expression and localization using MT-ND4-specific antibodies that target different epitopes of the protein. Available antibodies include polyclonal rabbit and mouse antibodies validated for Western blot, ELISA, and immunofluorescence applications .
-
Functional assays:
-
Mitochondrial membrane potential: Monitor changes using flow cytometry with appropriate fluorescent dyes .
What are the optimal methods for studying MT-ND4 mutations and their functional consequences?
To study MT-ND4 mutations:
-
Cell model generation: Develop LHON patient-derived hybrid cells (such as BLT2 cells) harboring specific MT-ND4 mutations.
-
Complementation assays: Transduce mutant cells with wild-type recombinant MT-ND4 and measure functional rescue.
-
Comparative analysis: Assess differences in:
-
ATP production through oxidative phosphorylation
-
Oxygen consumption rates
-
Respiratory chain complex assembly using blue native PAGE
-
Cell viability and susceptibility to oxidative stress
-
-
In vivo models: Test expression, tissue distribution, and functional effects through intravitreal injection in animal models (rabbits and macaques have been used successfully) .
How can researchers effectively clone and express the MT-ND4 gene from Lachesis muta muta?
A systematic approach includes:
-
RNA isolation: Extract total RNA from Lachesis muta muta tissue samples.
-
RT-PCR: Utilize specific primers designed based on conserved regions of MT-ND4 genes from related species.
-
Vector construction: Insert the amplified DNA product into an appropriate vector (pGEM has been used successfully for other Lachesis genes).
-
Sequencing and verification: Confirm the sequence integrity and identify the open reading frame.
-
Bioinformatic analysis: Determine molecular weight, isoelectric point, and key functional residues.
-
Recombinant expression: Transfer to an expression vector with a mitochondrial targeting sequence for proper subcellular localization .
How does the MT-ND4 gene sequence vary between Lachesis muta subspecies and other Viperidae?
MT-ND4 exhibits varying degrees of conservation across Viperidae species. Comparative analysis of Lachesis muta subspecies shows:
-
The Brazilian Atlantic bushmaster (Lachesis muta) MT-ND4 gene maintains structural similarities with other Viperidae but displays subspecies-specific nucleotide variations.
-
Phylogenetic analysis using complete mitochondrial genomes, including MT-ND4, provides stronger evolutionary relationship resolution than using limited gene sets.
-
The mitochondrial gene arrangement in Lachesis differs from other snake families but is consistent within Viperidae, with specific positioning of control regions and tRNA genes flanking protein-coding genes .
Understanding these variations is crucial for designing subspecies-specific primers and expression constructs.
What are the key considerations for codon optimization when expressing recombinant MT-ND4?
When designing codon-optimized MT-ND4 constructs:
-
Host-specific codon usage: Adapt the sequence to the intended expression system, considering the significant differences between snake and human/mammalian preferred codons.
-
Mitochondrial targeting: Include an efficient mitochondrial targeting sequence to ensure proper subcellular localization.
-
Structural elements preservation: Maintain critical functional domains while optimizing codons.
-
Expression verification: Confirm proper expression through RT-PCR, western blot, and functional assays.
-
Comparison with native expression: Establish baseline data on natural expression levels to calibrate recombinant expression .
How do mutations in MT-ND4 affect respiratory chain complex I assembly and function?
MT-ND4 mutations can significantly impair mitochondrial function through multiple mechanisms:
-
Complex I assembly disruption: Mutations can prevent proper incorporation of MT-ND4 into the respiratory chain complex I, leading to incomplete complex formation.
-
ATP production reduction: Studies with LHON-associated mutations show significantly decreased oxidative phosphorylation and ATP production.
-
Respiratory capacity impairment: Mutations reduce spare respiratory capacity, limiting cellular energy production under stress conditions.
-
Cellular consequences: These deficits lead to increased susceptibility to apoptosis and progressive cellular dysfunction, particularly in high-energy demanding tissues like retinal ganglion cells .
Gene therapy approaches using recombinant wild-type MT-ND4 have demonstrated the ability to rescue these defects, restoring ATP production and respiratory capacity in affected cells.
What techniques are most effective for studying the protein-protein interactions of MT-ND4 within complex I?
For investigating MT-ND4 interactions:
-
Blue native PAGE: To analyze intact respiratory complexes and identify assembled vs. unassembled MT-ND4.
-
Co-immunoprecipitation: Using antibodies against MT-ND4 or other complex I components to pull down interaction partners.
-
Proximity labeling techniques: BioID or APEX2 fusions to identify proteins in close proximity to MT-ND4 within the mitochondrial membrane.
-
Crosslinking mass spectrometry: To capture and identify direct interaction interfaces between MT-ND4 and other subunits.
-
Cryo-EM structural analysis: For high-resolution structural determination of MT-ND4 positioning within complex I .
These approaches can reveal how recombinant MT-ND4 integrates into existing complexes and how mutations disrupt critical interactions.
How can recombinant MT-ND4 be utilized as a therapeutic tool for mitochondrial disorders?
Recombinant MT-ND4 has shown promise as a therapeutic approach for mitochondrial disorders, particularly LHON:
-
Allotopic expression: Optimized nuclear expression of mitochondrial ND4 with appropriate targeting sequences allows the protein to be imported into mitochondria and assembled into complex I.
-
Delivery mechanisms: AAV2-based vectors have shown efficacy for ocular delivery, with the potential for targeted delivery to affected tissues.
-
Functional rescue: In LHON models, recombinant ND4 has demonstrated the ability to:
-
Prevent retinal ganglion cell degeneration
-
Preserve complex I function in optic nerves
-
Maintain visual function
-
-
Safety profile: Studies in animal models have shown sustained expression without harmful effects, supporting the therapeutic potential .
What are the key challenges in producing functional recombinant snake venom proteins compared to human mitochondrial proteins?
Producing functional recombinant proteins from snake venom sources presents unique challenges:
-
Structural complexity: Snake venom proteins often have complex disulfide bonding patterns that are difficult to reproduce in recombinant systems.
-
Post-translational modifications: Many venom proteins require specific modifications that may not occur correctly in heterologous expression systems.
-
Toxicity to expression hosts: Some venom components may be toxic to the cells producing them.
-
Conformational requirements: Proper folding may require specialized chaperones not present in standard expression systems.
-
Functional validation: Activity assays must be carefully designed to confirm biological function comparable to native proteins .
For MT-ND4 specifically, the challenge of proper mitochondrial targeting and membrane integration adds complexity to the recombinant production process.
How can researchers assess the potential cytotoxic effects of recombinant snake proteins compared to natural venom components?
A comprehensive cytotoxicity assessment approach includes:
| Assay Type | Methodology | Parameters Measured | Timeline |
|---|---|---|---|
| Cell Viability | Alamar Blue assay | Cellular metabolism | 24-72 hours |
| Cell Death Mechanism | Flow cytometry | Apoptosis and necrosis markers | 6, 12, 24 hours |
| Mitochondrial Function | JC-1 staining | Mitochondrial membrane potential | 6-24 hours |
| Autophagy Induction | GFP-LC3 expression | Autophagosome formation | 6 hours |
| Morphological Changes | Microscopy | Cell retraction, aggregation | 6-24 hours |
This sequential analysis allows researchers to determine:
-
The primary mechanisms of cytotoxicity
-
The timeline of cellular events following exposure
-
Differences between recombinant and native proteins
-
Concentration-dependent effects
These approaches provide critical data on the biological activity and potential therapeutic applications of recombinant proteins derived from Lachesis muta muta .
What are the optimal vector systems for expressing recombinant MT-ND4 for different research applications?
Selection of appropriate vector systems depends on the specific research goals:
-
For gene therapy applications: AAV2-based vectors have demonstrated efficacy in delivering ND4 with appropriate mitochondrial targeting sequences. These vectors allow for efficient transduction and sustained expression in target tissues, including retinal cells .
-
For protein characterization studies: Bacterial expression systems with fusion tags (His, GST, MBP) can facilitate purification, though mitochondrial membrane proteins often require specialized approaches to maintain proper folding.
-
For structural studies: Mammalian expression systems or insect cell systems may better preserve native conformation and post-translational modifications.
-
For functional studies: Lentiviral or retroviral vectors allow stable integration and long-term expression in cultured cells to study chronic effects on mitochondrial function .
Each system requires optimization of codon usage, signal sequences, and expression conditions specific to the protein's characteristics and experimental requirements.
How can researchers distinguish between endogenous and recombinant MT-ND4 in experimental systems?
Several approaches can effectively differentiate recombinant from endogenous MT-ND4:
-
Epitope tagging: Addition of small tags (FLAG, HA, myc) to the recombinant construct allows specific detection with tag antibodies.
-
Species-specific antibodies: When expressing human MT-ND4 in animal models or cell lines, species-specific antibodies can differentiate between the recombinant and endogenous proteins.
-
Codon-optimized sequence differences: Primers targeting unique nucleotide sequences in the codon-optimized recombinant gene allow selective PCR amplification or RNA detection.
-
Quantitative analysis: Western blot band intensity analysis can detect overexpression levels compared to baseline endogenous expression.
-
Subcellular fractionation: Assessment of mitochondrial vs. cytosolic distribution patterns during import processes .
