Recombinant Salmo salar NADH-ubiquinone oxidoreductase chain 3 (MT-ND3)
Description
Introduction to MT-ND3
NADH-ubiquinone oxidoreductase chain 3, commonly abbreviated as MT-ND3, is a mitochondrially encoded protein that functions as a subunit of Complex I in the electron transport chain. As one of seven mitochondrial genes encoding subunits of the NADH dehydrogenase (ubiquinone) enzyme, MT-ND3 plays a fundamental role in cellular energy production through oxidative phosphorylation. In Salmo salar (Atlantic salmon), this protein represents a vital component of mitochondrial metabolism, facilitating electron transfer from NADH to ubiquinone (coenzyme Q) .
Complex I, also known as NADH dehydrogenase, is the largest of the five complexes in the respiratory chain. It possesses a distinctive L-shaped structure consisting of a hydrophobic transmembrane domain and a hydrophilic peripheral arm. The MT-ND3 protein, along with other mitochondrially encoded subunits, forms the core of the transmembrane region and is characterized by its highly hydrophobic nature . This structural organization is essential for maintaining the protein's functional integrity and its role in the electron transport process.
Physical and Chemical Properties
The recombinant Salmo salar MT-ND3 protein is typically produced with an N-terminal 10xHis tag to facilitate purification and detection . The molecular weight of the protein is approximately 13 kDa, consistent with the typical size range for mitochondrially encoded subunits of Complex I . Commercial preparations of this recombinant protein exhibit high purity levels, generally exceeding 90% as determined by SDS-PAGE analysis .
Expression Systems
The recombinant Salmo salar MT-ND3 protein is typically produced using in vitro E. coli expression systems . This bacterial expression platform offers several advantages for the production of mitochondrial proteins, including high yield, cost-effectiveness, and the ability to incorporate specific modifications such as affinity tags. The choice of E. coli as an expression host allows for efficient production of functional MT-ND3 protein while maintaining its structural integrity.
During the recombinant expression process, the MT-ND3 gene is optimized for bacterial codon usage and cloned into appropriate expression vectors. The resulting constructs are then transformed into E. coli strains specifically designed for protein production. Following induction and expression, the recombinant protein is extracted and purified using affinity chromatography, leveraging the incorporated His-tag for selective isolation .
Purification and Quality Control
Purification of recombinant Salmo salar MT-ND3 typically involves multi-step chromatographic techniques. The initial capture is facilitated by immobilized metal affinity chromatography (IMAC), taking advantage of the N-terminal His-tag's affinity for metal ions. Subsequent purification steps may include ion exchange chromatography and size exclusion chromatography to achieve high purity.
Quality control measures commonly employed for recombinant MT-ND3 include SDS-PAGE analysis to confirm protein size and purity, western blotting for identity verification, and mass spectrometry for sequence confirmation. These analytical techniques ensure that the final product meets stringent quality standards for research applications. Commercial preparations typically achieve purity levels exceeding 90%, making them suitable for a wide range of biochemical and structural studies .
Role in Electron Transport Chain
The MT-ND3 protein serves as an integral component of Complex I (NADH:ubiquinone oxidoreductase), which catalyzes the first step in the mitochondrial electron transport chain. Complex I accepts electrons from NADH and transfers them to ubiquinone (coenzyme Q), coupled with the translocation of protons across the inner mitochondrial membrane. This process contributes to the establishment of the proton gradient that drives ATP synthesis through oxidative phosphorylation .
As one of the core subunits of Complex I, MT-ND3 is believed to participate in the formation of the ubiquinone binding site and play a role in the conformational changes associated with electron transfer. The protein's hydrophobic nature facilitates its integration into the membrane domain of Complex I, where it interacts with other subunits to maintain the structural and functional integrity of the complex .
Evolutionary Conservation
The MT-ND3 gene exhibits significant evolutionary conservation across vertebrate species, reflecting its fundamental importance in mitochondrial function. Comparative analyses of MT-ND3 sequences from different species provide valuable insights into the evolutionary relationships and functional constraints of this mitochondrial protein. The high degree of sequence similarity between the MT-ND3 proteins of Salmo salar (Atlantic salmon) and Salmo trutta (Brown trout) illustrates the conservation within closely related species .
Interestingly, in many species of birds and turtles, the MT-ND3 gene contains an extra nucleotide that is not translated into protein. This peculiarity has been attributed to translational frameshifting or RNA editing mechanisms that maintain the functionality of the reading frame. This feature has been used in phylogenetic studies to suggest evolutionary relationships between turtles and Archosauria .
Mitochondrial Function Studies
Recombinant Salmo salar MT-ND3 protein serves as a valuable tool for investigating mitochondrial function, particularly in the context of fish physiology and adaptation. The protein enables researchers to study the structural and functional characteristics of Complex I, including its assembly, electron transfer mechanisms, and interactions with inhibitors and substrates. Such studies contribute to our understanding of mitochondrial bioenergetics and the evolutionary adaptations of mitochondrial proteins in different species .
Research applications of recombinant MT-ND3 include in vitro reconstitution experiments, binding assays, and structural studies. By examining the interactions between MT-ND3 and other components of Complex I, researchers can gain insights into the molecular mechanisms underlying electron transport and proton translocation. Additionally, comparative studies using MT-ND3 from different species can reveal evolutionary adaptations in mitochondrial function .
Biomedical Implications
Although the search results focus primarily on MT-ND3 from Salmo salar, it is worth noting that variants in the human MT-ND3 gene have been associated with several mitochondrial disorders, including Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), Leigh's syndrome (LS), and Leber's hereditary optic neuropathy (LHON) . Recombinant MT-ND3 proteins from various species, including Salmo salar, can serve as models for investigating the structural and functional consequences of these pathogenic mutations.
By studying the effects of specific mutations on the stability, assembly, and function of MT-ND3, researchers can gain insights into the molecular mechanisms underlying mitochondrial disorders. Such investigations contribute to our understanding of mitochondrial dysfunction in human diseases and may facilitate the development of targeted therapeutic approaches.
Reconstitution and Handling
For optimal results, it is recommended to reconstitute the lyophilized MT-ND3 protein in deionized sterile water to a concentration of 0.1-1.0 mg/mL. The addition of glycerol to a final concentration of 5-50% is advisable for long-term storage, with 50% being the commonly used concentration in commercial preparations .
Working aliquots of the reconstituted protein can be stored at 4°C for up to one week, but repeated freezing and thawing should be avoided to prevent protein degradation and loss of activity. Before opening the vial, brief centrifugation is recommended to bring the contents to the bottom and ensure accurate handling .
Product Specs
Note: We will prioritize shipping the format we have in stock. However, if you have a specific format preference, please indicate your requirement when placing the order. We will prepare the product according to your request.
Note: All our proteins are shipped with standard blue ice packs by default. If you require dry ice shipping, please contact us in advance, and additional fees will apply.
Generally, the shelf life of the liquid form is 6 months at -20°C/-80°C. The shelf life of the lyophilized form is 12 months at -20°C/-80°C.
Target Background
KEGG: sasa:808308
Q&A
What is the biological role of MT-ND3 in Salmo salar?
MT-ND3 is a subunit of NADH-ubiquinone oxidoreductase, commonly known as Complex I, which is the first enzyme in the mitochondrial electron transport chain. This protein plays a critical role in oxidative phosphorylation by facilitating the transfer of electrons from NADH to ubiquinone, coupled with proton translocation across the mitochondrial inner membrane. This process generates an electrochemical gradient essential for ATP synthesis. In Salmo salar, MT-ND3 is encoded by mitochondrial DNA and forms part of the hydrophobic core of Complex I, which anchors the enzyme to the membrane and contributes to its structural stability .
How is recombinant MT-ND3 expressed and purified for research purposes?
Recombinant expression of MT-ND3 typically involves cloning the gene into an appropriate expression vector, followed by transformation into a host organism such as Escherichia coli. The choice of vector often includes features like strong promoters, affinity tags (e.g., His-tag), and codon optimization for efficient expression. Purification involves cell lysis, affinity chromatography (e.g., nickel-nitrilotriacetic acid columns), and further polishing steps like size-exclusion chromatography to ensure homogeneity. For membrane proteins like MT-ND3, detergents or lipid mimetics are used to maintain solubility and functionality during purification .
What are the structural characteristics of MT-ND3?
MT-ND3 is a small protein (~13 kDa) composed of approximately 115 amino acids. It is highly hydrophobic due to its role in forming part of the transmembrane region of Complex I. The protein's structure includes several transmembrane helices that interact with other subunits to stabilize the enzyme complex. In some species, untranslated nucleotides in the MT-ND3 gene have been observed, suggesting potential regulatory roles at the RNA level .
Why is Salmo salar used as a model organism for studying MT-ND3?
Salmo salar (Atlantic salmon) serves as a valuable model due to its ecological and economic importance, as well as its well-characterized mitochondrial genome. Studying MT-ND3 in this species provides insights into mitochondrial function and adaptation in aquatic environments. Additionally, salmonids exhibit unique mitochondrial DNA features, such as introgression and recombination events, which can inform broader evolutionary and functional studies .
What experimental techniques are used to study MT-ND3 activity?
The activity of MT-ND3 within Complex I can be assessed using spectrophotometric assays that measure NADH oxidation or ubiquinone reduction rates. Enzyme kinetics can be further analyzed under varying substrate concentrations to determine parameters like and . High-resolution respirometry allows researchers to evaluate Complex I function in isolated mitochondria or permeabilized cells by measuring oxygen consumption rates .
How do mutations in MT-ND3 affect Complex I function?
Mutations in MT-ND3 can disrupt electron transfer or proton pumping activities of Complex I, leading to reduced ATP production and increased reactive oxygen species (ROS) generation. For example, the m.10134C>A mutation has been shown to impair respiratory chain activity while maintaining protein stability . Tissue-specific effects have been observed, likely due to differential compensatory mechanisms or mitochondrial biogenesis across tissues .
What methods are used to identify mutations in MT-ND3?
Mutations in MT-ND3 can be identified using next-generation sequencing (NGS) techniques such as whole-genome sequencing or targeted mitochondrial DNA sequencing. Sanger sequencing remains a gold standard for validation due to its high accuracy. Quantitative PCR can be employed to assess heteroplasmy levels, providing insights into mutation distribution across tissues .
How does introgression influence MT-ND3 evolution in salmonids?
Introgression refers to the transfer of genetic material between species through hybridization and backcrossing. In salmonids, introgression events have been detected in mitochondrial genes like ND3 and ND6, resulting in phylogenetic inconsistencies that complicate species identification. These events highlight the dynamic nature of mitochondrial genomes and their potential role in adaptive evolution .
What challenges arise when studying recombinant membrane proteins like MT-ND3?
Studying recombinant membrane proteins poses challenges related to solubility, stability, and functional reconstitution. Detergents or lipid nanodiscs are required to mimic the native lipid environment during purification and biochemical assays. Additionally, achieving correct folding and post-translational modifications in heterologous systems can be difficult .
How can computational modeling aid in understanding MT-ND3 function?
Computational tools such as molecular dynamics simulations and homology modeling can provide insights into the structural dynamics of MT-ND3 within Complex I. These approaches allow researchers to predict mutation impacts on protein stability or interactions with other subunits. Docking studies can also explore potential inhibitors targeting specific sites on MT-ND3 .
How should controls be selected for experiments involving recombinant MT-ND3?
Experimental controls should include wild-type proteins expressed under identical conditions to account for background effects from host systems or purification steps. Negative controls lacking the target protein help identify non-specific activities or artifacts in assays .
What factors influence the reproducibility of MT-ND3 functional assays?
Reproducibility depends on consistent preparation of reagents (e.g., substrates, cofactors), standardized assay conditions (e.g., temperature, pH), and proper calibration of instruments like spectrophotometers or respirometers. Batch-to-batch variability in recombinant protein expression should also be minimized through rigorous quality control measures .
Data Tables
Below is an example table summarizing key mutations in MT-ND3 and their functional impacts:
