Recombinant Gorilla gorilla gorilla NADH dehydrogenase [ubiquinone] 1 subunit C2 (NDUFC2)

What is NDUFC2 and what are its alternative designations in scientific literature?

NDUFC2 (NADH dehydrogenase [ubiquinone] 1 subunit C2) is a protein component of mitochondrial complex I, part of the electron transport chain essential for cellular respiration. In scientific literature, this protein is alternatively known as Complex I-B14.5b (CI-B14.5b) or NADH-ubiquinone oxidoreductase subunit B14.5b . In Gorilla gorilla gorilla, the protein is associated with UniProt accession number Q0MQF8 and consists of 119 amino acids in its full-length form .

What is the role of NDUFC2 in mitochondrial complex I assembly?

NDUFC2 plays a critical role in the assembly and stability of mitochondrial complex I. Molecular studies indicate that NDUFC2 is essential for the assembly of the membrane arm of complex I, particularly involving the ND2 module and possibly the ND1 module . The protein is positioned within the proton pumping modules (specifically the ND2 module) of complex I and interfaces with multiple other subunits including NDUFA8, NDUFA10, NDUFA11, NDUFS5, NDUFC1, ND2, NDUFB1, NDUFB5, NDUFB10, NDUFB11, and ND4 .

Complexome profiling studies have demonstrated that loss of NDUFC2 causes concurrent loss of its associating subunits within the ND1 and ND2 modules, suggesting NDUFC2 may function as a scaffold for ND1 module formation . The absence of stable ND1 and ND2 modules indicates that these proximal P-modules do not pre-assemble independently without NDUFC2 .

How does NDUFC2 disruption affect mitochondrial function?

Disruption of NDUFC2 has profound effects on mitochondrial function. Research has demonstrated that NDUFC2 inhibition or deletion results in:

• Altered complex I assembly and reduced activity

• Decreased mitochondrial membrane potential

• Reduced ATP production

• Increased reactive oxygen species (ROS) generation

• Enhanced inflammatory responses both in vitro and in vivo

These functional perturbations highlight the essential nature of NDUFC2 in maintaining proper mitochondrial respiration and cellular energy metabolism. The cascade of effects resulting from NDUFC2 dysfunction ultimately leads to compromised cellular function and can contribute to pathological states, as observed in both animal models and human studies .

What are the recommended protocols for quantifying NDUFC2 expression levels?

For quantifying NDUFC2 expression in research settings, reverse transcription polymerase chain reaction (RT-PCR) has been successfully employed across various studies. Based on established methodologies, the following protocol is recommended:

• RNA Extraction: Extract total RNA from tissue or cellular samples using standard methods.

• cDNA Synthesis: Use 2 μg of total RNA for cDNA synthesis with Superscript III First-Strand (or equivalent) and random hexamer primers according to manufacturer's instructions.

• Primer Selection: The following oligonucleotides have been validated for rat Ndufc2:

  • Forward: 5′-GGCTTGTCTACATCGGCTTC-3′

  • Reverse: 5′-TGATGGTCCCTCACAGCATA-3′

• Real-time PCR Conditions: Perform RT-PCR using 2× SYBR Green PCR Master Mix with an initial denaturation step of 94°C for 10 minutes followed by 40 cycles of 94°C for 15 seconds and 60°C for 15 seconds.

• Normalization: Correct obtained values for β-actin mRNA levels, using primers:

  • Forward: 5′-AGATGACCCAGATCATGTTTGAGA-3′

  • Reverse: 5′-ATAGGGACATGCGGAGACCG-3′

Samples, standards, and negative controls should be analyzed in triplicate, with concentrations calculated from serially diluted standard curves .

What experimental approaches can be used to study the functional consequences of NDUFC2 manipulation?

Several complementary approaches have been validated for investigating the functional outcomes of NDUFC2 manipulation:

• Heterologous Complementation Assays: Using yeast strains deleted for homologous NADH dehydrogenase genes (e.g., Δndi1 in S. cerevisiae) to test NDUFC2 function through rescue experiments .

• Gene Silencing/Knockout Models:

  • In vitro: siRNA-mediated silencing in cell culture systems

  • In vivo: Heterozygous deletion models in rodents (e.g., SHRSR carrying heterozygous Ndufc2 deletion)

• Functional Assessment:

  • Complex I assembly: Assessed through complexome profiling and protein interaction studies

  • Mitochondrial membrane potential: Measured using fluorescent probes

  • ATP production: Quantified through luminescence-based assays

  • ROS generation: Detected using oxidation-sensitive fluorescent dyes

  • Inflammatory responses: Evaluated through cytokine profiling and gene expression analysis

• Genetic Sequence Analysis: Comparing NDUFC2 sequences across strains or species to identify potentially functional variants .

What is the evidence linking NDUFC2 dysfunction to mitochondrial diseases?

NDUFC2 dysfunction has been directly implicated in mitochondrial diseases, most notably early-onset Leigh syndrome. The first documented cases of mitochondrial disease caused by pathogenic variants in the NDUFC2 gene were reported in 2020 . The evidence linking NDUFC2 to these disorders includes:

• Genetic Evidence: Novel homozygous NDUFC2 variants were identified in consanguineous families with children presenting with Leigh syndrome.

• Clinical Presentation: Affected individuals exhibited clinical presentations consistent with Leigh syndrome, including radiological lesions of the basal ganglia, thalami, and substantia nigra.

• Biochemical Confirmation: Biochemical and functional analysis demonstrated:

  • Isolated complex I enzyme deficiency

  • Confirmed defects in assembly of the complex I holoenzyme

  • Formation of complex I assembly intermediates

• Mechanistic Insights: Complexome profiling of patient cell lines revealed that NDUFC2 deficiency impairs assembly of the membrane arm of complex I, particularly involving the ND2 module and possibly the ND1 module .

These findings collectively establish NDUFC2 as a critical component in mitochondrial function and implicate its dysfunction in the pathogenesis of mitochondrial disorders.

How does NDUFC2 contribute to stroke susceptibility?

Research has established a significant link between NDUFC2 dysfunction and increased stroke susceptibility through several mechanisms:

• Genetic Association: A quantitative trait locus (STR1/QTL) identified on rat chromosome 1 of stroke-prone spontaneously hypertensive rat (SHRSP) contributes approximately 20% of the stroke phenotype variance. NDUFC2, mapping 8 Mb from this locus, was found significantly down-regulated under stroke-permissive diet conditions in stroke-prone models compared to stroke-resistant models .

• Functional Impact:

  • NDUFC2 disruption alters complex I assembly and activity

  • Reduces mitochondrial membrane potential and ATP levels

  • Increases reactive oxygen species production

  • Enhances inflammatory responses both in vitro and in vivo

• Animal Model Validation: Stroke-resistant rats (SHRSR) carrying heterozygous NDUFC2 deletion showed renal abnormalities and stroke occurrence under specific dietary conditions, mimicking stroke-prone phenotypes .

• Human Clinical Correlation: In humans, specific genetic variants have been associated with NDUFC2 dysfunction and stroke risk:

  • T allele variant at NDUFC2/rs11237379 associates with reduced gene expression and increased early-onset ischemic stroke risk (odds ratio = 1.39; CI, 1.07–1.80; P=0.012)

  • Combined presence of TT/rs11237379 and A allele variant at NDUFC2/rs641836 further increases stroke risk (OR=1.56; CI, 1.14–2.13; P=0.006)

This multifaceted evidence establishes NDUFC2 as a contributor to stroke pathophysiology through mechanisms involving mitochondrial dysfunction and subsequent cellular stress responses.

How does the structure-function relationship of NDUFC2 compare across different species?

The structure-function relationship of NDUFC2 exhibits both conservation and divergence across species, reflecting its fundamental role in mitochondrial respiration. While complete comparative structural data specific to Gorilla gorilla gorilla NDUFC2 is limited, insights can be drawn from studies of homologous proteins:

• Structural Conservation: NDUFC2 maintains key functional domains across species, particularly the FAD and NAD(P)H binding motifs essential for electron transfer in the respiratory chain .

• Functional Differentiation: While primarily involved in NADH oxidation, the specific interactions and assembly requirements may vary. For instance:

  • In Leishmania, NDH2 (type II NADH dehydrogenase) is essential even in the presence of complex I, suggesting unique functions beyond those overlapping with complex I activities .

  • In mammals, NDUFC2 functions primarily as a structural component of complex I, interfacing with multiple other subunits to facilitate proper assembly and stability of the holoenzyme .

• Evolutionary Implications: The persistence of type II NADH dehydrogenases across evolution, despite structural differences from type I NADH dehydrogenases (complex I), suggests metabolic advantages that remain to be fully characterized. The Leishmania model may provide insights into these evolutionary adaptations .

Understanding these comparative aspects is crucial for interpreting experimental results across different model systems and for translating findings to human health applications.

What is known about the post-translational modifications of NDUFC2 and their impact on protein function?

Post-translational modifications (PTMs) of NDUFC2 represent an emerging area of research that can significantly impact the protein's function, interaction capabilities, and stability. Current knowledge about NDUFC2 PTMs is still developing, but several aspects warrant consideration:

• Potential Modification Sites: Analysis of the NDUFC2 amino acid sequence reveals multiple residues susceptible to post-translational modifications, including:

  • Serine, threonine, and tyrosine residues as potential phosphorylation sites

  • Lysine residues that may undergo acetylation, ubiquitination, or SUMOylation

  • Cysteine residues potentially subject to oxidation or nitrosylation

• Functional Implications: While not extensively characterized for NDUFC2 specifically, PTMs of complex I subunits generally can affect:

  • Protein stability and turnover

  • Assembly efficiency of the complex

  • Enzyme activity and regulation

  • Protein-protein interactions

  • Subcellular localization

• Research Challenges: Investigating PTMs of NDUFC2 presents several methodological challenges:

  • The membrane-associated nature of the protein complicates isolation and analysis

  • Low abundance of specific modified forms requires sensitive detection methods

  • Temporal dynamics of modifications necessitate carefully timed experimental designs

Future research employing mass spectrometry-based proteomics, targeted mutagenesis of modification sites, and temporal monitoring of NDUFC2 status will be essential to fully characterize the PTM landscape of this protein and its functional significance.

What experimental methods are most effective for studying NDUFC2 interactions with other complex I components?

Investigating NDUFC2 interactions with other complex I components requires sophisticated methodological approaches due to the membrane-embedded nature of these protein assemblies. The following methods have proven most effective:

• Complexome Profiling: This technique combines blue native gel electrophoresis with quantitative mass spectrometry to analyze the composition of protein complexes across the gel, allowing visualization of assembly intermediates and identification of interaction partners .

• Cryo-Electron Microscopy (Cryo-EM): High-resolution structural analysis has revolutionized our understanding of complex I architecture, revealing NDUFC2's position and interaction network within the holoenzyme. This approach has demonstrated that NDUFC2 has contact with 12 other subunits, including components of the ND1, ND2, and ND4 modules .

• Crosslinking Mass Spectrometry (XL-MS): This technique identifies protein-protein interaction interfaces by covalently linking proximal amino acid residues and subsequently identifying these linked peptides through mass spectrometry.

• Proximity-Based Labeling: Methods such as BioID or APEX2 proximity labeling allow for identification of proteins in close proximity to NDUFC2 within living cells.

• Heterologous Complementation Systems: Yeast models lacking endogenous NADH dehydrogenases provide a valuable system for functional assessment of NDUFC2 and its variants, as demonstrated in studies where Leishmania NDH2 expression rescued growth defects in Δndi1 S. cerevisiae strains .

• Split-GFP Analysis: This approach has been successfully employed to verify subcellular localization and protein-protein interactions, as demonstrated in research confirming that Leishmania NDH2 retained its endogenous location when expressed in yeast systems .

These complementary approaches provide a comprehensive toolkit for dissecting the complex interaction network of NDUFC2 and understanding its role in complex I assembly and function.

What are the potential therapeutic applications targeting NDUFC2 function in disease states?

Based on current understanding of NDUFC2's role in mitochondrial function and disease pathogenesis, several promising therapeutic directions warrant exploration:

• Mitochondrial Disorders: For conditions like Leigh syndrome associated with NDUFC2 mutations, potential approaches include:

  • Gene therapy strategies to deliver functional NDUFC2

  • Small molecule stabilizers of complex I assembly that might bypass NDUFC2 deficiency

  • Metabolic bypass strategies to support ATP production through alternative pathways

• Stroke Prevention and Treatment: Given NDUFC2's established role in stroke susceptibility:

  • Development of biomarkers based on NDUFC2 variants for stroke risk stratification

  • Targeted therapies to enhance NDUFC2 expression or activity in individuals with high-risk genetic variants

  • Mitochondrial-targeted antioxidants to mitigate downstream effects of NDUFC2 dysfunction

• Anti-parasitic Drug Development: The essential nature of NDH2 in Leishmania parasites, even in the presence of functional complex I, validates this enzyme as a promising drug target:

  • Selective inhibitors of parasite NDH2 that spare human complex I could provide effective anti-leishmanial therapies

  • Structural differences between human NDUFC2 and parasite NDH2 could be exploited for drug selectivity

Each of these therapeutic directions requires further research to develop effective interventions while minimizing off-target effects.

What technological advancements are needed to overcome current challenges in NDUFC2 research?

Advancing NDUFC2 research requires overcoming several technological limitations:

• Structural Biology Challenges:

  • Development of improved techniques for membrane protein crystallization

  • Advances in cryo-EM resolution for smaller protein subunits

  • Computational methods for predicting dynamic interactions within complex I

• Functional Assessment Tools:

  • Real-time monitoring of NDUFC2 incorporation into complex I during assembly

  • Development of specific antibodies or nanobodies for tracking NDUFC2 in living cells

  • Creation of conditional knockout models that allow temporal control of NDUFC2 expression

• Translational Research Needs:

  • High-throughput screening platforms for identifying compounds that modulate NDUFC2 expression or function

  • Development of humanized animal models that accurately recapitulate NDUFC2-related human diseases

  • Patient-derived cellular models (e.g., iPSCs) from individuals with NDUFC2 variants

• Systems Biology Approaches:

  • Integration of multi-omics data to understand NDUFC2 regulation in different physiological states

  • Network analysis tools to map the impact of NDUFC2 dysfunction across cellular pathways

  • Machine learning algorithms to predict phenotypic outcomes of specific NDUFC2 variants

Addressing these technological needs will accelerate progress in understanding NDUFC2 biology and developing therapeutic interventions for NDUFC2-related disorders.