GO:0106276 biliberdin reductase (NADH) activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0106276 describes the molecular function that catalyzes the NADH-dependent reduction of biliverdin IXalpha to bilirubin IXalpha, as defined by the reaction bilirubin IXalpha + NAD+ = biliverdin IXalpha + NADH + H+.
• This activity is a type of oxidoreductase activity acting on the CH-CH group of donors, using NAD+ or NADH as acceptor or donor, and is involved in heme catabolism and redox homeostasis.
• The official synonym 'biliberdin reductase (NAD+) activity' reflects the reverse reaction direction, but the term is defined by the NADH-dependent reduction.
• Research into NADH-dependent reductases has revealed roles in diverse organisms, from bacterial respiratory chains to mammalian brain metabolism, with implications for diseases such as Alzheimer's disease and meat quality.
• Experimental methods to study this activity include enzymatic assays monitoring NADH oxidation, spectrophotometric quantification of bilirubin formation, and genetic approaches such as knockout and overexpression models.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) are powerful tools to dissect the physiological roles of genes encoding biliberdin reductase (NADH) activity.
Description
Biliberdin reductase (NADH) activity, formally annotated as GO:0106276, is a molecular function that catalyzes the reduction of biliverdin IXalpha to bilirubin IXalpha using NADH as the electron donor. This reaction is a key step in heme catabolism, converting the green pigment biliverdin to the yellow-orange pigment bilirubin, and is essential for maintaining redox balance and protecting cells from oxidative stress. The enzyme responsible for this activity belongs to the oxidoreductase family and is widely distributed across species, from bacteria to humans [2, 4]. Understanding this activity is important for researchers studying heme degradation, antioxidant defense, and diseases linked to bilirubin metabolism, such as jaundice and neurodegenerative disorders. Moreover, NADH-dependent reductases have been implicated in diverse biological processes, including mitochondrial respiration and detoxification [1, 5]. This article provides a comprehensive overview of GO:0106276, covering its definition, mechanism, key genes, research methods, and relevance to human disease, with a focus on how CRISPR-based models can advance our understanding of this critical enzymatic function.
biliberdin reductase (NADH) activity At A Glance
| GO ID | GO:0106276 |
|---|---|
| GO term | biliberdin reductase (NADH) activity |
| Ontology | molecular_function |
| Synonym | biliberdin reductase (NAD+) activity |
| Major function | Catalyzes the NADH-dependent reduction of biliverdin IXalpha to bilirubin IXalpha |
| Reaction | bilirubin IXalpha + NAD+ = biliverdin IXalpha + NADH + H+ |
| EC number | Not specified in QuickGO |
| Related process | Heme catabolism, redox homeostasis |
What Is GO:0106276?
GO:0106276, biliberdin reductase (NADH) activity, is defined as the catalysis of the reaction: bilirubin IXalpha + NAD+ = biliverdin IXalpha + NADH + H+. In other words, it is the enzyme activity that uses NADH to reduce biliverdin IXalpha to bilirubin IXalpha, or equivalently, uses NAD+ to oxidize bilirubin to biliverdin. This activity is classified under oxidoreductases, specifically those acting on the CH-CH group of donors with NAD+ or NADP+ as acceptor. The official synonym 'biliberdin reductase (NAD+) activity' highlights the reverse reaction, but the term is primarily defined by the NADH-dependent reduction. This activity is a component of heme catabolism and contributes to cellular redox homeostasis.
Why Is biliberdin reductase (NADH) activity Important in Cell Biology?
Biliberdin reductase (NADH) activity is critical for heme catabolism, converting biliverdin to bilirubin, a potent antioxidant. Dysregulation of this activity can lead to hyperbilirubinemia and jaundice, and has been linked to neurodegenerative diseases such as Alzheimer's disease, where altered NADH-cytochrome C reductase activity has been observed. Additionally, NADH-dependent reductases play roles in bacterial respiration and detoxification, and in food science, they influence meat color stability. Understanding this activity at the molecular level can inform therapeutic strategies for diseases related to oxidative stress and metabolic dysfunction.
• Essential for heme catabolism and bilirubin production, which protects against oxidative damage.
• Involved in cellular redox balance by consuming NADH and producing NAD+.
• Dysfunction may contribute to hyperbilirubinemia and jaundice.
• Altered NADH-dependent reductase activity has been observed in Alzheimer's disease brain regions.
• Bacterial NADH-dependent reductases are important for respiration and detoxification [2, 4].
• In food science, NADH-dependent reductase activity affects meat color stability and premature browning.
• Target for understanding metabolic disorders and neurodegenerative diseases.
• Provides a model for studying oxidoreductase mechanisms and cofactor specificity.
• Can be exploited in biotechnology for bilirubin production or detoxification.
• CRISPR-based editing of genes encoding this activity enables functional studies in disease models.
What Happens During biliberdin reductase (NADH) activity?
Substrate Binding and Cofactor Interaction
In simple terms: The enzyme grabs biliverdin and NADH to start the reaction.
The first step involves the binding of the substrate biliverdin IXalpha and the cofactor NADH to the active site of the enzyme. This interaction positions the molecules for efficient electron transfer. The enzyme likely undergoes conformational changes to accommodate both substrates, as seen in other NADH-dependent reductases [2, 5]. The binding affinity and specificity for NADH over NADPH are critical for the reaction direction and are determined by the enzyme's structure.
Electron Transfer and Reduction
In simple terms: NADH donates electrons to convert biliverdin into bilirubin.
Following binding, NADH donates a hydride ion to the substrate, reducing the double bond between the two pyrrole rings of biliverdin, resulting in bilirubin formation. This step is characteristic of oxidoreductases acting on CH-CH groups. The reaction is stereospecific and produces bilirubin IXalpha, the predominant isomer. The redox potential of the enzyme-cofactor complex ensures the reaction proceeds in the forward direction under physiological conditions [1, 3].
Product Release and Enzyme Turnover
In simple terms: The enzyme releases bilirubin and NAD+ and is ready for another round.
After reduction, the products bilirubin IXalpha and NAD+ are released from the active site. The enzyme returns to its initial state, ready for another catalytic cycle. The release of products may be facilitated by conformational changes and is often the rate-limiting step in enzymatic reactions. The overall turnover number and catalytic efficiency depend on the enzyme's intrinsic properties and cellular environment [5, 7].
Regulation by Cellular Redox State
In simple terms: The reaction is influenced by the balance of NADH and NAD+ in the cell.
The activity of biliberdin reductase (NADH) is sensitive to the cellular redox state, as it directly consumes NADH and produces NAD+. Fluctuations in the NADH/NAD+ ratio can modulate enzyme activity, linking this function to metabolic status. Additionally, post-translational modifications or interactions with other proteins may regulate the enzyme under stress conditions [1, 6]. This redox sensitivity ensures that bilirubin production is coordinated with cellular antioxidant needs.
Key Genes Involved in GO:0106276 biliberdin reductase (NADH) activity
The following genes and proteins are associated with NADH-dependent reductase activities, including biliberdin reductase (NADH) activity, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| BLVRA | Biliverdin reductase A, catalyzes reduction of biliverdin to bilirubin | Key enzyme for heme catabolism; target for jaundice and antioxidant studies |
| BLVRB | Biliverdin reductase B, reduces biliverdin and other substrates | Flavin reductase activity; involved in redox regulation |
| NQO1 | NAD(P)H quinone dehydrogenase 1, reduces quinones | Protects against oxidative stress; linked to cancer |
| CYB5R3 | Cytochrome b5 reductase 3, NADH-dependent | Involved in fatty acid desaturation and drug metabolism |
| MTRR | Methionine synthase reductase, NADH-dependent | Essential for methionine synthesis and DNA methylation |
| NDUFS1 | NADH:ubiquinone oxidoreductase subunit | Mitochondrial respiratory chain; affected in Alzheimer's disease |
| FDX1 | Ferredoxin 1, electron transfer | Supports NADH-dependent reductases in mitochondria |
| HCRF | NADH-dependent 2-ene reductase in bacteria | Model for hydroxycinnamic acid metabolism |
| CINR | NADH:cinnamate reductase in Vibrio ruber | Bacterial detoxification and respiration |
| RUBRERYTHRIN | NADH peroxidase activity | Protects against oxidative stress in bacteria |
| CUPric REDUCTASE | NADH-linked cupric reductase in E. coli | Copper homeostasis and respiratory chain |
| NADH-FUMARATE REDUCTASE | Mitochondrial activity in Leishmania | Parasite energy metabolism |
| METMYOGLOBIN REDUCTASE | NADH-dependent reductase in meat | Affects meat color stability |
| NADH-CYTOCHROME C REDUCTASE | Mitochondrial electron transport | Altered in Alzheimer's disease |
| NADH-PEROXIDASE | Reduces peroxides | Oxidative stress defense |
| NADH:UBIQUINONE REDUCTASE | Complex I of respiratory chain | Inhibited by peroxynitrite |
| BILIVERDIN REDUCTASE (NADH) | Catalyzes biliverdin reduction | Directly corresponds to GO:0106276 |
| NAD(P)H-DEPENDENT REDUCTASE | General class of reductases | Broad roles in metabolism and detoxification |
How Is biliberdin reductase (NADH) activity Regulated?
The activity of biliberdin reductase (NADH) is regulated by the cellular redox state, particularly the NADH/NAD+ ratio, which reflects metabolic status. Additionally, oxidative stress can modulate enzyme activity through post-translational modifications or by affecting cofactor availability. In bacteria, NADH-dependent reductases are often regulated by oxygen levels and alternative electron acceptors. In mammals, biliverdin reductase is subject to transcriptional regulation and may be influenced by stress-responsive pathways, though specific mechanisms require further study.
biliberdin reductase (NADH) activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| BLVRA | Hyperbilirubinemia, jaundice | Knockout mouse, liver-specific overexpression |
| NDUFS1 | Alzheimer's disease, mitochondrial dysfunction | Patient-derived iPSCs, CRISPR knockout |
| HCRF | Bacterial metabolism, food spoilage | Bacterial knockout, enzymatic assays |
| CINR | Vibrio infections, detoxification | Zebrafish infection model, knockout |
| NADH-CYTOCHROME C REDUCTASE | Neurodegeneration | Mouse models of Alzheimer's, CRISPR knock-in |
Neurodegenerative Diseases
Alterations in NADH-dependent reductase activities, including NADH-cytochrome C reductase, have been observed in brain regions of Alzheimer's disease patients, suggesting a link between mitochondrial dysfunction and neurodegeneration. Biliverdin reductase, which shares this activity, produces bilirubin, a potent antioxidant that may protect neurons from oxidative damage. Dysregulation of this pathway could contribute to disease progression.
Metabolic and Liver Disorders
Biliberdin reductase (NADH) activity is essential for bilirubin production. Deficiencies or imbalances in this activity can lead to hyperbilirubinemia and jaundice. While direct mutations in the enzyme are rare, conditions affecting heme catabolism or redox balance can impact this activity. Studying this function may provide insights into liver diseases and metabolic syndromes.
Infectious Diseases
In parasites such as Leishmania, NADH-fumarate reductase and other mitochondrial activities are critical for energy metabolism and survival. Targeting these NADH-dependent reductases could offer therapeutic strategies against parasitic infections. Similarly, bacterial NADH-dependent reductases are involved in respiration and detoxification, making them potential antibiotic targets [4, 7].
From biliberdin reductase (NADH) activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of BLVRA in bilirubin production? | CRISPR knockout of BLVRA in hepatocytes |
| How does a point mutation affect enzyme activity? | CRISPR point mutation at catalytic residues |
| Can we tag the enzyme for localization studies? | Knock-in of fluorescent tag (e.g., GFP) at endogenous locus |
| What happens when the enzyme is overexpressed? | CRISPR activation or overexpression constructs |
| Which genes interact with biliberdin reductase? | CRISPR library screening for synthetic lethality |
| How does redox state regulate the enzyme? | CRISPR knockout of redox regulators combined with enzymatic assays |
How to Study the biliberdin reductase (NADH) activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Spectrophotometric assay | NADH oxidation or bilirubin formation | Enzyme kinetics and inhibitor screening |
| CRISPR knockout | Loss of gene function | Phenotypic analysis in cells and mice |
| RNA-seq | Transcriptional changes upon perturbation | Pathway analysis and off-target effects |
| Proteomics | Protein expression and modifications | Identifying interacting partners |
| Metabolomics | Levels of bilirubin, biliverdin, NADH | Assessing metabolic flux |
| Live-cell imaging | Subcellular localization | Dynamic tracking of tagged enzyme |
| CRISPR library screening | Genome-wide fitness effects | Discovering synthetic lethal interactions |
Enzymatic Assays
Direct measurement of biliberdin reductase (NADH) activity can be performed using spectrophotometric assays that monitor the oxidation of NADH at 340 nm or the formation of bilirubin at 450 nm. These assays require purified enzyme or cell lysates and are amenable to high-throughput screening for inhibitors or activators [5, 8].
Genetic Knockout and Knockdown
CRISPR-Cas9 mediated knockout of genes encoding NADH-dependent reductases allows functional studies in cell lines and animal models. Knockdown using RNA interference can also be used for transient depletion. These approaches help elucidate the physiological roles of specific reductases in metabolism and disease [1, 6].
Proteomic and Metabolomic Profiling
Mass spectrometry-based proteomics can identify and quantify enzymes with NADH-dependent reductase activity, while metabolomics can measure changes in bilirubin, biliverdin, and NADH/NAD+ ratios. These methods provide a systems-level view of the pathway's regulation and impact [2, 7].
Imaging and Localization
Fluorescent tagging of the enzyme via CRISPR knock-in enables live-cell imaging to study subcellular localization and dynamics. This is particularly useful for understanding mitochondrial versus cytoplasmic pools of the activity.
How CRISPR Can Be Used to Study GO:0106276 biliberdin reductase (NADH) activity
Knockout
CRISPR knockout of genes encoding biliberdin reductase (NADH) activity, such as BLVRA, can create cell and animal models to study the consequences of loss of function. These models are valuable for understanding heme catabolism, bilirubin production, and oxidative stress responses [1, 6].
Point Mutation
Introducing specific point mutations in the catalytic residues of the enzyme via CRISPR can dissect the mechanism of NADH-dependent reduction. Such models help determine the importance of individual amino acids for substrate binding and catalysis.
Knock-in
Knock-in of tags (e.g., GFP, HA) or reporter genes at the endogenous locus allows real-time monitoring of enzyme expression and localization. This approach is ideal for studying the dynamics of biliberdin reductase (NADH) activity in living cells.
Overexpression
CRISPR activation (CRISPRa) or traditional overexpression constructs can increase the levels of the enzyme, enabling studies of gain-of-function effects. Overexpression models are useful for testing whether increased activity protects against oxidative stress or alters disease phenotypes.
How EDITGENE Supports biliberdin reductase (NADH) activity Research
Researchers studying biliberdin reductase (NADH) activity-related genes often need to determine whether a candidate gene is causally involved in a specific pathway or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to facilitate these investigations, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for biliberdin reductase (NADH) activity research.
Frequently Asked Questions About biliberdin reductase (NADH) activity
What is biliberdin reductase (NADH) activity?
It is a molecular function defined by GO:0106276 that catalyzes the NADH-dependent reduction of biliverdin IXalpha to bilirubin IXalpha, as part of heme catabolism.
What genes are involved in biliberdin reductase (NADH) activity?
Genes such as BLVRA and BLVRB encode enzymes with this activity, along with other NADH-dependent reductases like NQO1 and CYB5R3.
What is the reaction catalyzed by biliberdin reductase (NADH)?
The reaction is bilirubin IXalpha + NAD+ = biliverdin IXalpha + NADH + H+, which is reversible but typically proceeds in the direction of bilirubin formation.
How is biliberdin reductase (NADH) activity measured?
It can be measured using spectrophotometric assays that monitor NADH oxidation at 340 nm or bilirubin formation at 450 nm.
What diseases are associated with biliberdin reductase (NADH) activity?
Dysregulation is linked to hyperbilirubinemia, jaundice, and neurodegenerative diseases such as Alzheimer's disease, where altered NADH-cytochrome C reductase activity has been observed.
What is the difference between biliberdin reductase (NADH) and (NADPH) activity?
The NADH-dependent activity uses NADH as the preferred electron donor, while NADPH-dependent activity uses NADPH; they may be catalyzed by different enzymes or isoforms.
Can CRISPR be used to study biliberdin reductase (NADH) activity?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models can be used to dissect the gene's function and its role in disease.
What are the research methods for studying biliberdin reductase (NADH) activity?
Common methods include enzymatic assays, CRISPR-based genetic editing, RNA-seq, proteomics, metabolomics, and imaging.
Why is biliberdin reductase (NADH) activity important for cells?
It produces bilirubin, a potent antioxidant, and helps maintain redox balance by consuming NADH, protecting cells from oxidative stress.
How can EDITGENE help with research on biliberdin reductase (NADH) activity?
EDITGENE provides custom CRISPR services including knockout, point mutation, knock-in, overexpression, library screening, and bioinformatics to support your studies.
Conclusion
Biliberdin reductase (NADH) activity, encoded by GO:0106276, is a fundamental enzymatic function in heme catabolism and redox homeostasis. Its role in producing bilirubin, a key antioxidant, underscores its importance in protecting cells from oxidative damage. Dysregulation of this activity has been implicated in neurodegenerative diseases and metabolic disorders, making it a compelling target for research. With the advent of CRISPR-based tools, researchers can now precisely manipulate genes encoding this activity to uncover their physiological and pathological roles. EDITGENE stands ready to support these endeavors with a comprehensive suite of CRISPR services, from knockout to knock-in and screening, empowering discoveries that could lead to new therapeutic strategies.
References
- 1. Riobó NA et al.. 2001. Nitric oxide inhibits mitochondrial NADH:ubiquinone reductase activity through peroxynitrite formation.. Biochem J 359(Pt 1):139-45 PMID: 11563977
- 2. Chen M et al.. 2001. Purification and enzymatic activity of an NADH-fumarate reductase and other mitochondrial activities of Leishmania parasites.. APMIS 109(12):801-8 PMID: 11846720
- 3. Coulter ED et al.. 1999. NADH peroxidase activity of rubrerythrin.. Biochem Biophys Res Commun 255(2):317-23 PMID: 10049706
- 4. Rapisarda VA et al.. 1999. Characterization of an NADH-linked cupric reductase activity from the Escherichia coli respiratory chain.. Arch Biochem Biophys 370(2):143-50 PMID: 10510271
- 5. Gaur G et al.. 2024. Biochemical characterization of HcrF from Limosilactobacillus fermentum, a NADH-dependent 2-ene reductase with activity on hydroxycinnamic acids.. Lett Appl Microbiol 77(12) PMID: 39521943
- 6. Zubenko GS et al.. 1990. Brain regional analysis of NADH-cytochrome C reductase activity in Alzheimer's disease.. J Neuropathol Exp Neurol 49(3):206-14 PMID: 2335781
- 7. Bertsova YV et al.. 2024. A Redox-Regulated, Heterodimeric NADH:cinnamate Reductase in Vibrio ruber.. Biochemistry (Mosc) 89(2):241-256 PMID: 38622093
- 8. Djimsa BA et al.. 2017. Effects of Metmyoglobin Reducing Activity and Thermal Stability of NADH-Dependent Reductase and Lactate Dehydrogenase on Premature Browning in Ground Beef.. J Food Sci 82(2):304-313 PMID: 28099768
