Recombinant Carassius auratus ATP synthase subunit a (mt-atp6)

What is Recombinant Carassius auratus ATP synthase subunit a (mt-atp6) and what is its role in cellular energy production?

ATP synthase subunit a (mt-atp6) in Carassius auratus is a critical component of the mitochondrial ATP synthase complex. This protein is part of the membrane-embedded F0 sector that forms the proton channel. Similar to its human counterpart ATP5F1B, mt-atp6 plays an essential role in proton translocation across the inner mitochondrial membrane during oxidative phosphorylation . The subunit forms part of the catalytic machinery where ATP is synthesized from ADP and inorganic phosphate by utilizing the electrochemical gradient of protons . Beyond ATP production, the ATP synthase complex also contributes significantly to the architecture of the mitochondrial inner membrane .

The recombinant form (product code CSB-YP015070DQG1) is produced in yeast expression systems to provide researchers with purified protein for experimental applications . This particular recombinant product is a partial protein, meaning it contains only a portion of the complete mt-atp6 sequence.

How does the structure of mt-atp6 in Carassius auratus compare to homologous proteins in other species?

While direct structural comparison data is limited in current literature, we can infer significant conservation based on the fundamental role of ATP synthase across species. In humans, pathogenic variants in MT-ATP6 affect specific functional domains that are likely conserved in Carassius auratus . For example, human MT-ATP6 variants at position m.8993T>G (p.Leu156Arg) are associated with Leigh syndrome and NARP, suggesting this region is critical for proper function .

The catalytic subunits of ATP synthase can adopt different conformations when binding to substrates, similar to what has been observed with human ATP5F1B binding to Mg-ADP (βDP), Mg-ATP (βTP), or remaining empty (βE) . This structural flexibility is likely conserved in Carassius auratus mt-atp6, particularly in regions interacting with other ATP synthase components.

What are the optimal storage and handling conditions for recombinant mt-atp6 protein in laboratory settings?

For optimal maintenance of protein integrity, the following conditions are recommended:

For proper handling, briefly centrifuge the vial before opening to bring contents to the bottom . Reconstitution should be performed according to manufacturer specifications, though complete reconstitution instructions were not provided in the available data . To maintain protein stability, it is critical to avoid repeated freezing and thawing cycles, which can lead to protein denaturation and loss of activity.

What expression systems are most effective for producing functional recombinant Carassius auratus mt-atp6?

Yeast expression systems have proven effective for producing recombinant Carassius auratus mt-atp6 with purity levels exceeding 85% as determined by SDS-PAGE . Yeast systems offer several advantages for expressing mitochondrial proteins:

• They provide a eukaryotic cellular environment that supports proper protein folding and some post-translational modifications.

• Yeast mitochondria share structural similarities with those of higher eukaryotes, facilitating proper expression of mitochondrial proteins.

• They allow for controlled induction conditions and relatively high protein yields.

When designing expression strategies, researchers should consider that mt-atp6 is naturally encoded in the mitochondrial genome, which uses a slightly different genetic code than nuclear genes. Codon optimization for the expression system may be necessary to achieve optimal expression levels. Additionally, the inclusion of appropriate affinity tags can facilitate purification while minimizing interference with protein function.

How can researchers effectively validate the functionality of purified recombinant mt-atp6?

Functional validation of purified mt-atp6 requires methodologies that assess its ability to participate in proton translocation and ATP synthesis. The following approaches are recommended:

• ATP synthesis assays: Measure ATP production in reconstituted proteoliposomes containing recombinant mt-atp6 alongside other necessary ATP synthase components. This can assess whether the recombinant protein can properly integrate into a functional complex.

• Proton translocation measurements: Use pH-sensitive fluorescent dyes to monitor proton movement across membranes containing the recombinant protein.

• Complex stability assessment: Blue Native PAGE analysis can determine whether mt-atp6 properly incorporates into the ATP synthase complex and maintains its structural integrity.

• Comparative functional analysis: Compare activity parameters between the recombinant protein and native ATP synthase from Carassius auratus mitochondria.

• Inhibitor binding studies: Assess the protein's interaction with known ATP synthase inhibitors as a measure of proper folding and functional conformation.

What techniques are most appropriate for investigating interactions between mt-atp6 and other ATP synthase subunits?

Understanding the interactions between mt-atp6 and other ATP synthase components is crucial for comprehending complex assembly and function. Several techniques can effectively investigate these interactions:

• Co-immunoprecipitation: Using antibodies against mt-atp6 or other subunits to pull down the entire complex and analyze its composition.

• Crosslinking mass spectrometry: This technique can identify specific amino acid residues involved in subunit interactions.

• Yeast two-hybrid or mammalian two-hybrid systems: These can detect direct protein-protein interactions, though may be challenging for membrane proteins.

• Bioluminescence resonance energy transfer (BRET) or Förster resonance energy transfer (FRET): These approaches can detect interactions in living cells when proteins are tagged with appropriate fluorophores.

• Cryo-electron microscopy: This can visualize the entire ATP synthase complex architecture and the position of mt-atp6 within it.

When studying a partial recombinant protein as described in the product information , researchers should be mindful that certain interaction domains may be absent, potentially affecting binding affinity and complex formation.

How can researchers investigate the impact of specific mutations in mt-atp6 on ATP synthase function?

Based on studies of human MT-ATP6 variants, several approaches can be applied to investigate mutations in Carassius auratus mt-atp6:

• Site-directed mutagenesis: Introduce specific mutations into the recombinant protein expression construct to create variants of interest. For example, mutations corresponding to human variants at positions analogous to m.8993T>G or m.9032T>C could be particularly informative .

• Enzymatic activity assays: Compare ATP synthesis rates and ATP hydrolysis activities between wild-type and mutant proteins. Human studies have shown that pathogenic variants can significantly reduce ATP synthase activity and increase reactive oxygen species (ROS) production .

• Structural analysis: Assess how mutations affect protein folding, stability, and complex assembly. Human studies indicate certain MT-ATP6 mutations can lead to increased formation of F1 subcomplexes .

• Proton translocation efficiency: Measure how mutations affect the protein's ability to translocate protons across membranes, a critical function for ATP synthesis.

• Heterologous expression in model systems: Express mutant variants in appropriate model systems to assess phenotypic effects.

The table below summarizes known effects of mutations in human MT-ATP6 that could guide investigations in Carassius auratus:

What insights can comparative studies of Carassius auratus mt-atp6 provide for understanding mitochondrial diseases in humans?

Comparative studies between Carassius auratus mt-atp6 and human MT-ATP6 can yield valuable insights into mitochondrial disease mechanisms:

• Conserved functional domains: Identifying evolutionarily conserved regions between fish and human mt-atp6 can highlight critical functional domains where mutations are likely to cause disease .

• Differential responses to mutations: Comparing the effects of equivalent mutations in fish and human proteins can reveal species-specific compensatory mechanisms or vulnerabilities.

• Environmental adaptations: Goldfish have evolved remarkable adaptations to survive in low-oxygen environments, potentially involving modifications to ATP synthase function. Understanding these adaptations may provide insights for therapeutic approaches to mitochondrial disorders.

• Structure-function relationships: The ability to produce recombinant Carassius auratus mt-atp6 in higher quantities than human protein may facilitate structural studies that inform understanding of human disease variants.

Human MT-ATP6 mutations are associated with diverse clinical phenotypes, including Leigh syndrome, neuropathy, ataxia, retinitis pigmentosa (NARP), and cardiomyopathy . Comparative studies could help elucidate why certain mutations specifically affect particular tissues despite mitochondria being present in almost all cell types.

How can metabolomic approaches enhance our understanding of mt-atp6 function and dysfunction?

Metabolomic analysis can provide comprehensive insights into the downstream effects of mt-atp6 function or dysfunction. While the search results don't specifically address metabolomics in relation to mt-atp6, search result describes metabolomic analysis in a different genetic modification study in Carassius auratus that can inform similar approaches:

• Pathway analysis: Metabolomic studies can identify affected biochemical pathways when mt-atp6 function is altered. For example, the study in search result identified enrichment in Thiamine metabolism and Nicotinate and Nicotinamide Metabolism pathways following genetic modification in Carassius auratus .

• Biomarker identification: Specific metabolites may serve as biomarkers for ATP synthase dysfunction. The study in search result found upregulation of beneficial metabolites like β-Nicotinamide mononucleotide, DL-Glutamine, and Thiamine pyrophosphate .

• Integration with other omics data: Combining metabolomics with transcriptomics and proteomics can provide a comprehensive understanding of how mt-atp6 modifications affect cellular function.

• Comparative metabolomics: Comparing metabolic profiles between wild-type and mt-atp6 modified systems could reveal compensatory mechanisms that cells employ to maintain energy homeostasis despite ATP synthase alterations.

A comprehensive metabolomic analysis would typically include:

• Principal Component Analysis (PCA) for quality control and sample clustering

• Partial Least Squares Discriminant Analysis (PLS-DA) for identifying differentially abundant metabolites

• Pathway enrichment analysis to identify affected biochemical pathways

• Targeted validation of key metabolites using standards

What are the current limitations in studying mitochondrial membrane proteins like mt-atp6, and how can researchers overcome them?

Studying mitochondrial membrane proteins presents several significant challenges:

• Heteroplasmy assessment: In human studies, determining the true level of mutational load can be complex as heteroplasmy levels vary between tissues . Even apparently homoplasmic variants in one analysis may prove heteroplasmic with more sensitive techniques or extended culture, as shown with the m.9205delTA variant . Researchers should employ multiple techniques to accurately assess heteroplasmy levels and analyze multiple tissue types when possible.

• Protein solubility: As a highly hydrophobic membrane protein, mt-atp6 presents challenges for expression, purification, and structural studies. This can be addressed through:

  • Optimized detergent selection for extraction and purification

  • Nanodiscs or amphipol systems for maintaining native-like membrane environments

  • Lipid reconstitution approaches for functional studies

• Complex assembly: Studying mt-atp6 in isolation provides limited functional insights since it operates within the larger ATP synthase complex. Researchers should consider:

  • Co-expression strategies for multiple ATP synthase subunits

  • In vitro reconstitution of partial or complete complexes

  • Careful selection of experimental conditions that preserve native interactions

• Mitochondrial targeting: When expressing recombinant mt-atp6 in heterologous systems, ensuring proper targeting to mitochondria can be challenging. Potential solutions include:

  • Inclusion of appropriate mitochondrial targeting sequences

  • Verification of localization using fluorescent tags or subcellular fractionation

  • Development of mitochondria-specific expression systems

How does the variability in recombinant protein expression systems affect mt-atp6 research outcomes?

Expression system selection significantly impacts recombinant mt-atp6 research:

• Post-translational modifications: Different expression systems (bacterial, yeast, insect, mammalian) provide varying capabilities for post-translational modifications. While yeast systems (as used for the product in search result ) offer some eukaryotic modifications, they may not perfectly replicate modifications specific to fish mitochondria.

• Protein folding: The hydrophobic nature of mt-atp6 presents folding challenges in heterologous systems. Yeast expression systems generally provide better membrane protein folding machinery than bacterial systems but may still not perfectly replicate the native mitochondrial environment.

• Codon usage: Mitochondrial genes use a slightly different genetic code than nuclear genes. When expressing mt-atp6 in heterologous systems, codon optimization may be necessary for efficient translation.

• Yield versus authenticity trade-offs: Higher-yielding systems (like bacteria) often produce less authentically folded protein, while systems producing more native-like protein (mammalian cells) typically provide lower yields.

• Purity considerations: The product in search result indicates a purity of >85% as determined by SDS-PAGE. Researchers should consider whether this purity level is sufficient for their specific applications, particularly for structural studies that may require higher purity.

What strategies can researchers employ to investigate tissue-specific effects of mt-atp6 function or dysfunction?

To effectively study tissue-specific aspects of mt-atp6 function, researchers can employ several strategies:

• Tissue-specific expression studies: Analyze expression levels of mt-atp6 across different tissues in Carassius auratus to identify potential tissue-specific regulation.

• Cell-type specific analyses: Isolate specific cell types from different tissues to examine whether mt-atp6 function varies between cell types within the same tissue.

• Tissue-specific metabolomics: Compare metabolic profiles across tissues when mt-atp6 function is altered to identify tissue-specific metabolic adaptations.

• Ex vivo tissue studies: Examine ATP synthesis rates and oxygen consumption in isolated tissue samples to assess tissue-specific bioenergetic parameters.

• Tissue culture models: Develop primary culture models from different Carassius auratus tissues to study mt-atp6 function under controlled conditions.

Human studies have demonstrated that MT-ATP6 mutations can have remarkably tissue-specific effects. For example, the m.8528T>C variant primarily affects cardiac tissue, causing hypertrophic cardiomyopathy, while other variants predominantly affect the nervous system . Understanding the molecular basis for these tissue specificities in fish models could provide valuable insights applicable to human mitochondrial diseases.

How might gene editing approaches be applied to study mt-atp6 function in vivo in Carassius auratus?

Based on the gene editing study described in search result , which successfully created a new crucian carp strain by knocking out bmp6, similar approaches could be applied to study mt-atp6:

• Challenges of mitochondrial genome editing: Unlike nuclear genes, mitochondrial genes present unique challenges for gene editing due to the difficulty of delivering editing machinery to mitochondria and the multicopy nature of the mitochondrial genome.

• Potential approaches:

  • Import of pre-formed ribonucleoprotein complexes into mitochondria

  • Development of mitochondrially-targeted CRISPR systems

  • Base editing approaches that have shown promise for mitochondrial DNA

  • TALENs with mitochondrial targeting sequences, which have been more successful than CRISPR for mtDNA editing

• Phenotypic analysis: Following successful editing, comprehensive phenotypic analysis would be required, similar to the approach in the bmp6 study that examined growth, reproduction, nutrient components, muscle texture, and metabolites .

• Tissue-specific effects: Special attention should be paid to tissues with high energy demands, such as muscle, brain, and heart, where mt-atp6 modifications would likely have the most pronounced effects.

What emerging technologies might advance our understanding of ATP synthase structure and function in Carassius auratus?

Several cutting-edge technologies hold promise for advancing mt-atp6 research:

• Cryo-electron microscopy advancements: Recent advances in cryo-EM have revolutionized membrane protein structural biology, potentially enabling high-resolution structures of Carassius auratus ATP synthase with and without mutations.

• Single-molecule techniques: Methods such as single-molecule FRET and high-speed atomic force microscopy could provide insights into the dynamics of ATP synthase function, particularly the conformational changes during the catalytic cycle.

• In-cell NMR: This emerging technique could potentially provide structural and dynamic information about mt-atp6 in its native cellular environment.

• Organoid technology: Development of fish-derived organoid systems could provide more physiologically relevant models for studying mt-atp6 function in different tissue contexts.

• Mitochondrial proteomics: Advanced proteomics approaches can identify the complete interactome of mt-atp6, revealing previously unknown protein-protein interactions that influence function.

How can comparative evolutionary studies of mt-atp6 contribute to our understanding of mitochondrial function adaptation?

Evolutionary studies of mt-atp6 across species can provide valuable insights:

• Adaptation to environmental conditions: Carassius auratus has evolved remarkable tolerance to low-oxygen conditions, potentially involving adaptations in ATP synthase function. Comparative studies with less tolerant species could reveal adaptive mechanisms.

• Conservation analysis: Identifying highly conserved residues across evolutionarily distant species can highlight functionally critical regions of mt-atp6 that might be intolerant to mutation.

• Positive selection analysis: Detecting residues under positive selection pressure could identify regions that have adapted to specific environmental conditions or metabolic demands.

• Interspecies hybrid analysis: Examining the compatibility of mt-atp6 with nuclear-encoded ATP synthase components from different species could reveal constraints on mito-nuclear co-evolution.

• Environmental adaptation signatures: Comparing mt-atp6 sequences from fish species in different environments (varying temperatures, oxygen levels, pH, etc.) could reveal how environmental pressures shape ATP synthase evolution.

The understanding gained from evolutionary studies could inform both basic science questions about energy metabolism adaptation and potential therapeutic approaches for human mitochondrial diseases involving ATP synthase dysfunction.