GO:0050614 Delta24-sterol reductase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0050614 (Delta24-sterol reductase activity) catalyzes the NADPH-dependent reduction of the C-24 double bond in sterol precursors, converting 5-alpha-cholest-7-en-3-beta-ol to 5-alpha-cholesta-7,24-dien-3-beta-ol.
• The enzyme is a sterol:NADP+ delta24-oxidoreductase that participates in cholesterol and ergosterol biosynthesis pathways.
• In the bacterium Coxiella burnetii, a functional Delta24 sterol reductase is expressed and contributes to host-derived sterol modification.
• Inhibitors of Delta24-sterol reductase, such as azasteroids and related nitrogen-containing steroids, disrupt ergosterol biosynthesis and impair insect growth and development.
• The enzyme is a validated antifungal and insecticidal target because its inhibition blocks membrane sterol production.
• Research on GO:0050614 uses knockout, point-mutation, knock-in, and overexpression cell models combined with lipidomics and CRISPR screening.
Description
Delta24-sterol reductase activity (GO:0050614) is a molecular function defined by the catalysis of the reaction NADP+ + 5-alpha-cholest-7-en-3-beta-ol = NADPH + H+ + 5-alpha-cholesta-7,24-dien-3-beta-ol. This oxidoreductase removes the C-24 double bond from sterol intermediates, a step required for the production of mature sterols in eukaryotes and some bacteria. The enzyme is also known as D24-sterol reductase, lanosterol delta24-reductase, lanosterol Delta(24)-reductase, and sterol:NADP+ delta24-oxidoreductase. Because sterols are essential membrane components and signaling molecules, the activity of this enzyme influences membrane integrity, cell growth, and development. Researchers study GO:0050614 to understand sterol biosynthesis, to develop antifungal and insecticidal agents, and to model metabolic disorders linked to sterol imbalance. The availability of functional assays in Coxiella burnetii and inhibitor studies in fungi and insects has made this enzyme a tractable target for both basic and applied research.
Delta24-sterol reductase activity At A Glance
| GO ID | GO:0050614 |
|---|---|
| GO term | Delta24-sterol reductase activity |
| Ontology | molecular_function |
| Synonym | D24-sterol reductase activity; lanosterol delta24-reductase activity; lanosterol Delta(24)-reductase activity; sterol:NADP+ delta24-oxidoreductase activity |
| Major function | Catalyzes the NADPH-dependent reduction of the C-24 double bond in sterol precursors |
| Reaction | NADP+ + 5-alpha-cholest-7-en-3-beta-ol = NADPH + H+ + 5-alpha-cholesta-7,24-dien-3-beta-ol |
| Cofactor | NADPH/NADP+ |
| Pathway context | Sterol biosynthesis (cholesterol and ergosterol pathways) |
| Organisms | Bacteria (e.g., Coxiella burnetii), fungi, insects, and other eukaryotes |
What Is GO:0050614?
In simple terms, GO:0050614 describes an enzyme that uses NADPH to remove a double bond at the 24th carbon of a sterol molecule. The official definition is: Catalysis of the reaction: NADP+ + 5-alpha-cholest-7-en-3-beta-ol = NADPH + H+ + 5-alpha-cholesta-7,24-dien-3-beta-ol. This activity is a sterol:NADP+ delta24-oxidoreductase that participates in sterol biosynthesis, including cholesterol and ergosterol pathways.
Why Is Delta24-sterol reductase activity Important in Cell Biology?
Delta24-sterol reductase activity is important because it controls a committed step in sterol biosynthesis, and its inhibition leads to the accumulation of toxic sterol intermediates and loss of membrane function. In pathogenic fungi, blocking this activity compromises ergosterol production, which is the target of many antifungal drugs. In insects, azasteroid inhibitors of this enzyme disrupt growth and development, suggesting its potential as an insecticide target. In Coxiella burnetii, a functional Delta24 sterol reductase is expressed and may modify host sterols during infection. Thus, GO:0050614 is relevant to infectious disease, agriculture, and fundamental cell biology.
• Essential for cholesterol biosynthesis in eukaryotes.
• Required for ergosterol biosynthesis in fungi, a key antifungal target.
• Inhibition by azasteroids blocks insect growth and development.
• Expressed by Coxiella burnetii and potentially involved in host-pathogen interactions.
• Loss of activity causes accumulation of sterol intermediates that can be cytotoxic.
• Provides a biochemical marker for sterol pathway flux in metabolic studies.
• Enables development of selective inhibitors for antifungal and insecticidal applications.
• Links sterol metabolism to membrane integrity and cell signaling.
• Serves as a model enzyme for studying NADPH-dependent oxidoreductases.
• Potential target for treating sterol-related disorders and infections.
What Happens During Delta24-sterol reductase activity?
Substrate binding and cofactor recruitment
In simple terms: The enzyme grabs a sterol molecule and an NADPH molecule to start the reaction.
Delta24-sterol reductase binds its sterol substrate, such as 5-alpha-cholest-7-en-3-beta-ol, and the cofactor NADPH. The enzyme is classified as a sterol:NADP+ delta24-oxidoreductase, indicating that it uses NADPH as the electron donor. This step is essential for positioning the C-24 double bond for reduction.
Hydride transfer and double bond reduction
In simple terms: The enzyme transfers a hydrogen from NADPH to the sterol, removing the double bond.
The catalytic mechanism involves hydride transfer from NADPH to the C-24 position of the sterol, reducing the double bond and producing 5-alpha-cholesta-7,24-dien-3-beta-ol. The reaction also releases NADP+ and H+. This reduction is a key step in converting sterol intermediates to their saturated forms.
Product release and pathway continuation
In simple terms: The modified sterol is released and moves on to the next step in sterol biosynthesis.
After reduction, the product 5-alpha-cholesta-7,24-dien-3-beta-ol is released and can enter subsequent enzymatic steps in cholesterol or ergosterol biosynthesis. The activity of Delta24-sterol reductase thus determines the flux of sterol intermediates toward mature sterols.
Inhibition by azasteroids and nitrogen-containing steroids
In simple terms: Certain drug-like molecules can block the enzyme, stopping sterol production.
Structurally modified azasteroids and related nitrogen-containing steroids inhibit Delta24-sterol reductase, leading to disrupted sterol biosynthesis. In insects, these inhibitors impair growth and development, demonstrating the physiological importance of the enzyme. In fungi, inhibition of ergosterol biosynthesis by targeting this activity is a validated antifungal strategy.
Key Genes Involved in GO:0050614 Delta24-sterol reductase activity
The following genes and proteins are directly or functionally linked to Delta24-sterol reductase activity (GO:0050614) based on published experimental evidence.
| Gene | Major Role | Research Relevance |
|---|---|---|
| Coxiella burnetii Delta24 sterol reductase | Functional Delta24 sterol reductase expressed by the bacterium | Studied for host sterol modification during infection |
| Fungal ergosterol biosynthesis genes (e.g., ERG4) | Encode enzymes in the ergosterol pathway including Delta24 reduction | Targets for antifungal inhibitors |
| Insect sterol reductase genes | Mediate sterol metabolism in insects | Targets for azasteroid insecticides |
| NADPH-cytochrome P450 reductase | Provides reducing equivalents for some sterol reductases | Potential redox partner in sterol biosynthesis |
| Sterol C-24 methyltransferase | Acts upstream of Delta24 reduction in sterol pathway | Context for pathway flux studies |
| Sterol C-14 reductase | Another sterol reductase in the pathway | Comparative studies of reductase mechanisms |
| Sterol C-8 isomerase | Works downstream of Delta24 reduction | Pathway ordering and regulation |
| Sterol C-5 desaturase | Introduces double bonds in sterols | Balances saturation/unsaturation |
| HMG-CoA reductase | Rate-limiting enzyme in sterol biosynthesis | Upstream regulator of pathway flux |
| Squalene monooxygenase | Early sterol biosynthesis enzyme | Provides substrates for Delta24 reductase |
| Lanosterol synthase | Cyclizes squalene to lanosterol | Substrate supply for Delta24 reduction |
| Cytochrome P450 sterol 14-alpha demethylase | Modifies sterol intermediates | Antifungal target in same pathway |
| Sterol O-acyltransferase | Esterifies sterols | Affects free sterol pools for reduction |
| ABC sterol transporters | Transport sterols across membranes | Link to membrane sterol homeostasis |
| Nuclear sterol receptors (e.g., SREBP) | Regulate sterol biosynthesis genes | Transcriptional control of pathway |
| Insect ecdysone synthesis enzymes | Use sterols for hormone production | Link to development and growth |
How Is Delta24-sterol reductase activity Regulated?
Delta24-sterol reductase activity is regulated at multiple levels. In sterol biosynthesis pathways, the expression of enzymes is often controlled by feedback mechanisms responsive to sterol levels, such as SREBP in mammals. In fungi, ergosterol depletion can upregulate pathway genes, including those encoding Delta24 reductases. In insects, developmental signals and hormonal cues may influence sterol reductase activity to meet changing membrane and hormone demands. Additionally, the availability of NADPH and the redox state of the cell can affect enzymatic activity. Inhibitors such as azasteroids can directly block the enzyme, providing a pharmacological means of regulation.
Delta24-sterol reductase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| Coxiella burnetii Delta24 sterol reductase | Q fever and intracellular survival | Knockout of bacterial gene in cell infection models |
| Fungal ERG4 (Delta24 reductase) | Fungal infections and antifungal resistance | Point mutations in fungal strains for resistance studies |
| Insect sterol reductase | Insect growth and development | Knockdown or inhibitor treatment in insect cell lines |
| Human sterol reductase (DHCR24) | Sterol metabolism disorders | Knockout and overexpression in human cell lines |
| NADPH-cytochrome P450 reductase | Redox imbalance in sterol pathways | Knock-in of tagged enzyme for interaction studies |
Fungal infections and antifungal resistance
Delta24-sterol reductase is part of the ergosterol biosynthesis pathway in fungi. Inhibition of this activity by azasteroids and related compounds disrupts ergosterol production, leading to antifungal effects. Resistance to antifungal drugs can arise through mutations or overexpression of sterol pathway enzymes, making Delta24-sterol reductase a relevant target for new antifungal development.
Insect-borne diseases and pest control
Azasteroid inhibitors of Delta24-sterol reductase impair insect growth and development, suggesting that this enzyme is a potential target for insecticides. Controlling insect populations is important for reducing the spread of vector-borne diseases and agricultural pests.
Bacterial pathogenesis and host sterol manipulation
Coxiella burnetii expresses a functional Delta24 sterol reductase, which may modify host-derived sterols during infection. This activity could contribute to the pathogen's ability to survive within host cells and cause Q fever. Understanding this enzyme may reveal new therapeutic strategies against intracellular bacteria.
From Delta24-sterol reductase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of Delta24-sterol reductase affect sterol composition? | CRISPR knockout cell lines followed by lipidomics |
| Which point mutations alter enzyme activity? | Point-mutation knock-in cell lines |
| Can a tagged enzyme be used for localization studies? | Knock-in of fluorescent or affinity tags |
| Does overexpression increase sterol flux? | Overexpression cell models |
| Which genes interact with Delta24 reductase? | CRISPR library screening and bioinformatics |
| Can inhibitors block enzyme activity in living cells? | Inhibitor treatment in wild-type and knockout cells |
How to Study the Delta24-sterol reductase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Lipidomics (LC-MS) | Sterol intermediate and product levels | Quantify enzyme activity in cells |
| Enzymatic assay | NADPH consumption or product formation | In vitro inhibitor testing |
| CRISPR knockout screening | Gene essentiality and pathway interactions | Identify modifiers of sterol metabolism |
| RNA-seq | Gene expression changes | Regulatory studies of sterol pathway |
| Proteomics | Protein abundance and modifications | Post-translational regulation |
| Fluorescence microscopy | Subcellular localization of tagged enzyme | Knock-in cell lines |
| Insect growth assays | Developmental toxicity of inhibitors | Insecticide discovery |
| Antifungal susceptibility testing | Fungal growth inhibition | Antifungal drug development |
Lipidomics and sterol profiling
Mass spectrometry-based lipidomics can quantify sterol intermediates and products to measure Delta24-sterol reductase activity in cells and tissues. This method is essential for confirming changes in 5-alpha-cholest-7-en-3-beta-ol and 5-alpha-cholesta-7,24-dien-3-beta-ol levels.
Enzymatic assays with NADPH
In vitro enzymatic assays using purified or recombinant enzyme, sterol substrate, and NADPH can directly measure the oxidoreductase activity by monitoring NADPH consumption or product formation. Such assays are used to test inhibitors and determine kinetic parameters.
CRISPR screening and functional genomics
Genome-wide CRISPR knockout or activation screens can identify genes that modify Delta24-sterol reductase activity or sterol pathway flux. These screens link the enzyme to broader cellular networks and potential drug targets.
Transcriptomics and proteomics
RNA-seq and proteomics can measure expression levels of Delta24-sterol reductase and related pathway genes under different conditions, revealing regulatory mechanisms. These methods help identify feedback loops and stress responses affecting sterol biosynthesis.
How CRISPR Can Be Used to Study GO:0050614 Delta24-sterol reductase activity
Knockout
CRISPR knockout of Delta24-sterol reductase genes can abolish enzyme activity, leading to accumulation of sterol intermediates and altered membrane properties. Knockout cell lines are used to study the consequences of loss of function and to validate inhibitor specificity.
Point Mutation
Point mutations can be introduced into the catalytic domain of Delta24-sterol reductase to dissect residues required for substrate binding or NADPH interaction. Such models help understand enzyme mechanism and resistance to inhibitors.
Knock-in
Knock-in of tagged versions of the enzyme (e.g., GFP or FLAG) allows visualization and immunoprecipitation studies to determine localization and interacting partners. Knock-in of disease-associated mutations can model altered sterol metabolism.
Overexpression
Overexpression of Delta24-sterol reductase can increase sterol pathway flux and alter cellular sterol composition. This approach is useful for producing recombinant enzyme for biochemical assays and for studying pathway regulation.
How EDITGENE Supports Delta24-sterol reductase activity Research
Researchers studying Delta24-sterol reductase activity-related genes often need to determine whether a candidate gene is causally involved in sterol metabolism, membrane integrity, or disease. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for Delta24-sterol reductase activity research.
Frequently Asked Questions About Delta24-sterol reductase activity
What is Delta24-sterol reductase activity?
It is a molecular function (GO:0050614) that catalyzes the NADPH-dependent reduction of the C-24 double bond in sterol precursors, converting 5-alpha-cholest-7-en-3-beta-ol to 5-alpha-cholesta-7,24-dien-3-beta-ol.
What genes are involved in Delta24-sterol reductase activity?
Genes include the Coxiella burnetii Delta24 sterol reductase, fungal ERG4, insect sterol reductases, and related sterol pathway genes such as HMG-CoA reductase and lanosterol synthase.
What is the reaction catalyzed by GO:0050614?
The reaction is NADP+ + 5-alpha-cholest-7-en-3-beta-ol = NADPH + H+ + 5-alpha-cholesta-7,24-dien-3-beta-ol.
Which organisms express Delta24-sterol reductase?
It is expressed in bacteria such as Coxiella burnetii, fungi, insects, and other eukaryotes.
How is Delta24-sterol reductase activity regulated?
It is regulated by sterol feedback mechanisms, NADPH availability, and developmental signals, and can be inhibited by azasteroids.
What diseases are linked to Delta24-sterol reductase?
It is linked to fungal infections, insect development, and bacterial pathogenesis such as Q fever.
Can CRISPR be used to study Delta24-sterol reductase?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are used to study its function and regulation.
What methods measure Delta24-sterol reductase activity?
Lipidomics, enzymatic assays with NADPH, CRISPR screening, RNA-seq, and proteomics are commonly used.
Why is Delta24-sterol reductase a drug target?
Because its inhibition blocks ergosterol biosynthesis in fungi and impairs insect growth, making it a target for antifungals and insecticides.
What are the synonyms for GO:0050614?
Synonyms include D24-sterol reductase activity, lanosterol delta24-reductase activity, lanosterol Delta(24)-reductase activity, and sterol:NADP+ delta24-oxidoreductase activity.
Conclusion
Delta24-sterol reductase activity (GO:0050614) is a critical enzymatic function in sterol biosynthesis, with roles in cholesterol and ergosterol production, membrane integrity, and host-pathogen interactions. Its inhibition by azasteroids and related compounds has validated it as a target for antifungal and insecticidal development. Continued research using CRISPR models and advanced omics will further elucidate its regulation and therapeutic potential.
References
- 1. Gilk SD et al.. 2010. Coxiella burnetii expresses a functional Δ24 sterol reductase.. J Bacteriol 192(23):6154-9 PMID: 20870767
- 2. Chung SK et al.. 2000. Design and synthesis of potential inhibitors of the ergosterol biosynthesis as antifungal agents.. Bioorg Med Chem 8(10):2475-86 PMID: 11058043
- 3. Thompson MJ et al.. 1975. Inhibitive effects of structurally modified azasteroids and related nitrogen containing steroids on insect growth and development.. Lipids 10(10):615-22 PMID: 1186447
