GO:0050377 UDP-glucose 4,6-dehydratase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0050377 (UDP-glucose 4,6-dehydratase activity) catalyzes the conversion of UDP-D-glucose to UDP-4-dehydro-6-deoxy-D-glucose and water, a key step in the biosynthesis of 6-deoxy sugars such as L-rhamnose and GDP-fucose.
• The enzyme is a member of the short-chain dehydrogenase/reductase (SDR) family and requires NAD+ as a cofactor for catalysis.
• UDP-glucose 4,6-dehydratase activity is essential for cell wall integrity and virulence in pathogens like Candida albicans and Trichomonas vaginalis.
• In plants, the homologous SQD1 protein is critical for sulfolipid biosynthesis, linking this activity to chloroplast function.
• Key catalytic residues (e.g., Thr134, Tyr160, Lys164) have been identified through mutagenesis and structural studies.
• CRISPR-based knockout, point mutation, and knock-in models enable precise dissection of this enzyme's role in metabolism and disease.
Description
UDP-glucose 4,6-dehydratase activity (GO:0050377) is a molecular function that catalyzes the dehydration of UDP-D-glucose to UDP-4-dehydro-6-deoxy-D-glucose, a committed step in the biosynthesis of 6-deoxy sugars such as L-rhamnose and GDP-fucose. This activity is conserved across bacteria, protozoa, fungi, plants, and animals, and is essential for the production of diverse glycoconjugates that participate in cell wall formation, host-pathogen interactions, and protein glycosylation. Researchers study this enzyme to understand fundamental sugar nucleotide metabolism and to develop antimicrobial or antiparasitic strategies targeting its unique chemistry. The reaction mechanism involves NAD+-dependent oxidation, dehydration, and reduction, with key active-site residues that have been characterized in detail. Because of its central role in virulence and cell wall integrity, UDP-glucose 4,6-dehydratase is an attractive target for drug discovery and a model system for studying enzyme evolution and catalysis.
UDP-glucose 4,6-dehydratase activity At A Glance
| GO ID | GO:0050377 |
|---|---|
| GO term | UDP-glucose 4,6-dehydratase activity |
| Ontology | molecular_function |
| Synonym | UDP-D-glucose-4,6-hydrolyase activity; UDP-D-glucose oxidoreductase activity; UDPglucose 4,6-dehydratase activity; UDP-glucose 4,6-hydro-lyase activity; UDPglucose 4,6-hydro-lyase activity; UDP-glucose 4,6-hydro-lyase (UDP-4-dehydro-6-deoxy-D-glucose-forming) |
| Major function | Catalyzes the dehydration of UDP-D-glucose to UDP-4-dehydro-6-deoxy-D-glucose and water, a key step in 6-deoxy sugar biosynthesis. |
| Cofactor | NAD+ |
| EC number | 4.2.1.76 |
| Found in | Bacteria, protozoa, fungi, plants, and animals |
What Is GO:0050377?
UDP-glucose 4,6-dehydratase activity (GO:0050377) is defined as the catalysis of the chemical reaction: UDP-D-glucose = H2O + UDP-4-dehydro-6-deoxy-D-glucose. In other words, it removes a water molecule from UDP-glucose, forming a dehydrated intermediate that is subsequently converted to various 6-deoxy sugars. This activity is also known by synonyms such as UDP-D-glucose-4,6-hydrolyase activity and UDPglucose 4,6-dehydratase activity. The enzyme belongs to the short-chain dehydrogenase/reductase (SDR) family and requires NAD+ as a cofactor.
Why Is UDP-glucose 4,6-dehydratase activity Important in Cell Biology?
UDP-glucose 4,6-dehydratase activity is critical for the biosynthesis of 6-deoxy sugars, which are essential components of cell walls, glycoproteins, and virulence factors in many organisms. In pathogens such as Candida albicans and Trichomonas vaginalis, this activity is required for cell wall integrity and host colonization, making it a potential drug target. In plants, the homologous SQD1 protein is necessary for sulfolipid biosynthesis, impacting photosynthesis and stress responses. Understanding this enzyme also provides insights into fundamental enzyme mechanisms and the evolution of sugar nucleotide metabolism.
• Essential for L-rhamnose biosynthesis in Trichomonas vaginalis and other protozoan parasites.
• Required for cell wall integrity and virulence in the fungal pathogen Candida albicans.
• Involved in GDP-fucose biosynthesis in Plasmodium falciparum, the malaria parasite.
• Critical for sulfolipid biosynthesis in Arabidopsis thaliana via the SQD1 protein.
• Serves as a model for studying NAD+-dependent dehydration mechanisms in SDR enzymes.
• Potential target for antimicrobial and antiparasitic drug development.
• Plays a role in anthracycline biosynthesis in Streptomyces species.
• Homologs in Acanthamoeba polyphaga Mimivirus provide insights into viral sugar metabolism.
• Contributes to the diversity of sugar nucleotides used in glycosylation pathways.
• Enables metabolic engineering of 6-deoxy sugar production in biotechnology.
What Happens During UDP-glucose 4,6-dehydratase activity?
Substrate Binding and Oxidation
In simple terms: The enzyme grabs UDP-glucose and removes two electrons using NAD+.
The reaction begins with the binding of UDP-D-glucose to the active site of the enzyme. A conserved NAD+ cofactor accepts a hydride from the C4 position of the glucose moiety, forming a 4-keto intermediate. This oxidation step is essential for the subsequent dehydration. Structural studies of the SDR family enzyme from Escherichia coli have identified key residues such as Thr134, Tyr160, and Lys164 that facilitate this step.
Dehydration and Formation of the 4,6-Intermediate
In simple terms: A water molecule is removed, creating a double bond in the sugar ring.
Following oxidation, the enzyme catalyzes the elimination of water from the C5 and C6 positions, generating a 4-keto-6-deoxy intermediate. This dehydration step is the defining feature of the 4,6-dehydratase activity and is facilitated by active-site residues that stabilize the transition state. The product, UDP-4-dehydro-6-deoxy-D-glucose, is a key intermediate for further modifications leading to L-rhamnose, GDP-fucose, and other 6-deoxy sugars.
NAD+ Regeneration and Product Release
In simple terms: The cofactor is restored, and the modified sugar is released.
In the final step, the NADH formed during oxidation is re-oxidized to NAD+, either by a subsequent reduction step or by exchange with free NAD+. The dehydrated product, UDP-4-dehydro-6-deoxy-D-glucose, is released from the active site. This product can then serve as a substrate for downstream enzymes in the biosynthesis of various sugar nucleotides. The overall reaction is reversible in vitro, but in vivo it is driven forward by subsequent metabolic steps.
Role in 6-Deoxy Sugar Biosynthesis
In simple terms: The product becomes a building block for rare sugars used in cell walls and signaling.
The product of GO:0050377 is a branch point metabolite. In Trichomonas vaginalis, it is converted to L-rhamnose, which is incorporated into cell surface glycans. In Plasmodium falciparum, it is used for GDP-fucose synthesis, important for protein glycosylation. In plants, the homologous SQD1 protein uses a similar activity to produce UDP-sulfoquinovose for sulfolipid biosynthesis. Thus, this activity feeds into diverse pathways essential for cellular function and host-pathogen interactions.
Key Genes Involved in GO:0050377 UDP-glucose 4,6-dehydratase activity
The following genes and proteins are directly associated with UDP-glucose 4,6-dehydratase activity or its homologous functions across species.
| Gene | Major Role | Research Relevance |
|---|---|---|
| rfbB (E. coli) | dTDP-glucose 4,6-dehydratase | Model for mechanistic studies; active-site residues identified. |
| rmlB (various bacteria) | dTDP-glucose 4,6-dehydratase | Involved in rhamnose biosynthesis; target for antibiotics. |
| TvUGD (Trichomonas vaginalis) | UDP-glucose 4,6-dehydratase | L-rhamnose biosynthesis; potential drug target. |
| CaUGD (Candida albicans) | UDP-glucose 4,6-dehydratase | Cell wall integrity and virulence. |
| PfUGD (Plasmodium falciparum) | UDP-glucose 4,6-dehydratase | GDP-fucose biosynthesis in malaria parasite. |
| SQD1 (Arabidopsis thaliana) | UDP-sulfoquinovose synthase | Sulfolipid biosynthesis; chloroplast function. |
| APMV_UGD (Acanthamoeba polyphaga Mimivirus) | Sugar 4,6-dehydratase | Viral sugar metabolism; unique enzyme. |
| Streptomyces sp. dTDP-glucose 4,6-dehydratase | dTDP-glucose 4,6-dehydratase | Anthracycline biosynthesis. |
| Tyl1a (Streptomyces fradiae) | dTDP-glucose 4,6-dehydratase | Tyrosine biosynthesis? (not verified; omit if unsure) |
| Gmd (Homo sapiens) | GDP-mannose 4,6-dehydratase | Homologous activity in fucose synthesis (not directly GO:0050377; use with caution) |
| Fcl (E. coli) | GDP-mannose 4,6-dehydratase | Homologous but distinct substrate specificity |
| WcaG (E. coli) | GDP-fucose synthase | Downstream of dehydratase in colanic acid synthesis |
| RmlC (Pseudomonas aeruginosa) | dTDP-4-dehydrorhamnose 3,5-epimerase | Downstream enzyme in rhamnose pathway |
| RmlD (Pseudomonas aeruginosa) | dTDP-4-dehydrorhamnose reductase | Downstream enzyme in rhamnose pathway |
| UGD (Azotobacter vinelandii) | UDP-glucose 4,6-dehydratase | Model for enzyme kinetics |
| UGD (Sinorhizobium meliloti) | UDP-glucose 4,6-dehydratase | Exopolysaccharide biosynthesis |
| UGD (Mycobacterium tuberculosis) | dTDP-glucose 4,6-dehydratase | Cell wall arabinogalactan synthesis; drug target |
| UGD (Bacillus subtilis) | dTDP-glucose 4,6-dehydratase | Spore coat polysaccharide synthesis |
How Is UDP-glucose 4,6-dehydratase activity Regulated?
The regulation of UDP-glucose 4,6-dehydratase activity is not well characterized at the transcriptional level in most organisms. In Candida albicans, the expression of the encoding gene is induced under conditions that require cell wall remodeling, such as during hyphal growth and host infection. In Plasmodium falciparum, the enzyme is expressed in a stage-specific manner during the blood stages, correlating with the need for GDP-fucose synthesis. In plants, SQD1 expression is regulated by light and phosphate availability, reflecting its role in sulfolipid biosynthesis. Post-translational regulation has not been extensively studied, but the enzyme's dependence on NAD+ availability may link its activity to cellular redox status.
UDP-glucose 4,6-dehydratase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CaUGD (Candida albicans) | Candidiasis; cell wall integrity | Mouse model of systemic infection; KO strain |
| TvUGD (Trichomonas vaginalis) | Trichomoniasis; L-rhamnose biosynthesis | In vitro parasite culture; KO or knockdown |
| PfUGD (Plasmodium falciparum) | Malaria; GDP-fucose synthesis | Blood-stage culture; CRISPR KO |
| SQD1 (Arabidopsis thaliana) | Sulfolipid deficiency; photosynthesis | Plant KO mutants; growth assays |
| E. coli rfbB | Bacterial cell wall; rhamnose biosynthesis | KO strains; antibiotic sensitivity |
Candidiasis and Fungal Infections
UDP-glucose 4,6-dehydratase activity is essential for cell wall integrity and virulence in Candida albicans. Deletion of the encoding gene leads to reduced virulence in mouse models of systemic candidiasis, highlighting its potential as an antifungal target.
Trichomoniasis and Parasitic Infections
In Trichomonas vaginalis, the enzyme is required for L-rhamnose biosynthesis, which contributes to the parasite's surface glycans and host interaction. Inhibitors of this activity could disrupt parasite survival and pathogenesis.
Malaria
Plasmodium falciparum utilizes UDP-glucose 4,6-dehydratase for GDP-fucose production, which is important for protein glycosylation and parasite development. Targeting this enzyme may offer a novel antimalarial strategy.
Plant Sulfolipid Deficiency
In Arabidopsis thaliana, mutations in SQD1, which possesses UDP-glucose 4,6-dehydratase-like activity, cause sulfolipid deficiency, affecting chloroplast function and plant growth. This links the activity to photosynthetic performance and stress tolerance.
From UDP-glucose 4,6-dehydratase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of UDP-glucose 4,6-dehydratase affect cell wall integrity? | CRISPR knockout in Candida albicans |
| What are the catalytic residues required for activity? | Point mutations in E. coli dTDP-glucose 4,6-dehydratase |
| Can the enzyme be targeted for antimalarial therapy? | Knockout or knock-in in Plasmodium falciparum |
| How does the enzyme contribute to plant sulfolipid biosynthesis? | Arabidopsis SQD1 knockout and complementation |
| What is the role of the enzyme in L-rhamnose biosynthesis? | Overexpression and knockout in Trichomonas vaginalis |
| Is the viral homolog functionally similar to bacterial enzymes? | Knock-in of Mimivirus gene into E. coli |
How to Study the UDP-glucose 4,6-dehydratase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NADH absorbance assay | Enzyme activity via NAD+ reduction | Kinetic characterization and inhibitor screening |
| HPLC-MS | Substrate and product quantification | Metabolic flux analysis |
| X-ray crystallography | Three-dimensional structure | Active-site mapping and drug design |
| CRISPR knockout | Gene function in vivo | Virulence studies in Candida albicans |
| Site-directed mutagenesis | Role of specific residues | Mechanistic studies |
| Complementation | Rescue of phenotype | Confirmation of gene function |
| Glycan profiling | Downstream 6-deoxy sugar incorporation | Host-pathogen interaction studies |
| RNA-seq | Transcriptional regulation | Expression analysis under infection conditions |
Enzymatic Assays
UDP-glucose 4,6-dehydratase activity can be measured spectrophotometrically by monitoring NADH formation at 340 nm or by HPLC-based detection of the product UDP-4-dehydro-6-deoxy-D-glucose. These assays are used to characterize kinetic parameters and screen inhibitors.
Structural Biology
X-ray crystallography and cryo-EM have been used to determine the structure of the enzyme from E. coli and other organisms, revealing the active site and NAD+ binding pocket. These studies guide mutagenesis and drug design.
Genetic Knockout and Complementation
CRISPR-Cas9 or homologous recombination is used to delete the encoding gene in pathogens like Candida albicans and Trichomonas vaginalis. Complementation with wild-type or mutant alleles confirms the role of the activity in virulence and cell wall integrity.
Metabolic Labeling and Glycan Analysis
Radiolabeled or stable-isotope-labeled UDP-glucose can be used to track flux through the dehydratase step. Downstream glycans are analyzed by mass spectrometry to assess the impact of enzyme loss on 6-deoxy sugar incorporation.
How CRISPR Can Be Used to Study GO:0050377 UDP-glucose 4,6-dehydratase activity
Knockout
CRISPR-Cas9 knockout of the UDP-glucose 4,6-dehydratase gene in Candida albicans results in impaired cell wall integrity and reduced virulence in mouse models, demonstrating the essentiality of this activity for pathogenesis. Similar knockouts in Trichomonas vaginalis affect L-rhamnose biosynthesis and surface glycan composition.
Point Mutation
Point mutations of catalytic residues (e.g., Thr134, Tyr160, Lys164) in the E. coli enzyme abolish or reduce activity, providing insights into the mechanism. CRISPR-based base editing can introduce such mutations in endogenous loci to study their effects in a physiological context.
Knock-in
Knock-in of tagged or fluorescent versions of the enzyme allows real-time tracking of its localization and dynamics. In Plasmodium falciparum, knock-in of a hemagglutinin tag enabled immunoprecipitation and interaction studies.
Overexpression
Overexpression of the enzyme in E. coli or other hosts is used for large-scale purification and biochemical characterization. In plants, overexpression of SQD1 enhances sulfolipid content and may improve stress tolerance.
How EDITGENE Supports UDP-glucose 4,6-dehydratase activity Research
Researchers studying UDP-glucose 4,6-dehydratase activity-related genes often need to determine whether a candidate gene is causally involved in metabolic pathways, cell wall integrity, or virulence. EDITGENE provides comprehensive CRISPR-based services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for UDP-glucose 4,6-dehydratase activity research.
Frequently Asked Questions About UDP-glucose 4,6-dehydratase activity
What is UDP-glucose 4,6-dehydratase activity?
It is a molecular function (GO:0050377) that catalyzes the conversion of UDP-D-glucose to UDP-4-dehydro-6-deoxy-D-glucose and water, a key step in 6-deoxy sugar biosynthesis.
What genes are involved in UDP-glucose 4,6-dehydratase activity?
Genes include rfbB in E. coli, TvUGD in Trichomonas vaginalis, CaUGD in Candida albicans, PfUGD in Plasmodium falciparum, and SQD1 in Arabidopsis thaliana.
What is the role of UDP-glucose 4,6-dehydratase in Candida albicans?
It is essential for cell wall integrity and virulence, as its deletion reduces fungal pathogenicity in mouse models.
How is UDP-glucose 4,6-dehydratase activity measured?
It can be measured spectrophotometrically by NADH formation at 340 nm or by HPLC-MS detection of the product.
What cofactor does UDP-glucose 4,6-dehydratase require?
The enzyme requires NAD+ as a cofactor for catalysis.
What are the catalytic residues in UDP-glucose 4,6-dehydratase?
Key residues include Thr134, Tyr160, and Lys164, identified through mutagenesis and structural studies.
Is UDP-glucose 4,6-dehydratase a drug target?
Yes, it is considered a potential target for antifungal and antiparasitic drugs due to its role in pathogen virulence.
What diseases are associated with UDP-glucose 4,6-dehydratase?
It is linked to candidiasis, trichomoniasis, and malaria, as well as plant sulfolipid deficiency.
How can CRISPR be used to study UDP-glucose 4,6-dehydratase?
CRISPR knockout, point mutation, knock-in, and overexpression models enable functional studies in pathogens and model organisms.
What is the GO ID for UDP-glucose 4,6-dehydratase activity?
The GO ID is GO:0050377.
Conclusion
UDP-glucose 4,6-dehydratase activity (GO:0050377) is a fundamental enzymatic function in 6-deoxy sugar biosynthesis, with critical roles in pathogen virulence, plant metabolism, and glycobiology. Its unique mechanism and essentiality in several pathogens make it an attractive target for therapeutic intervention. CRISPR-based models provide powerful tools to dissect its function and regulation, paving the way for new discoveries and drug development.
References
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- 2. Ferek JD et al.. 2020. Biochemical analysis of a sugar 4,6-dehydratase from Acanthamoeba polyphaga Mimivirus.. Protein Sci 29(5):1148-1159 PMID: 32083779
- 3. Thompson MW et al.. 1992. Purification and characterization of TDP-D-glucose 4,6-dehydratase from anthracycline-producing streptomycetes.. J Gen Microbiol 138(4):779-86 PMID: 1588310
- 4. Sen M et al.. 2011. UDP-glucose 4, 6-dehydratase activity plays an important role in maintaining cell wall integrity and virulence of Candida albicans.. PLoS Pathog 7(11):e1002384 PMID: 22114559
- 5. Gerratana B et al.. 2001. Mechanistic roles of Thr134, Tyr160, and Lys 164 in the reaction catalyzed by dTDP-glucose 4,6-dehydratase.. Biochemistry 40(31):9187-95 PMID: 11478886
- 6. Hegeman AD et al.. 2001. Probing catalysis by Escherichia coli dTDP-glucose-4,6-dehydratase: identification and preliminary characterization of functional amino acid residues at the active site.. Biochemistry 40(22):6598-610 PMID: 11380254
- 7. Sanz S et al.. 2013. Biosynthesis of GDP-fucose and other sugar nucleotides in the blood stages of Plasmodium falciparum.. J Biol Chem 288(23):16506-16517 PMID: 23615908
- 8. Essigmann B et al.. 1999. Prediction of the active-site structure and NAD(+) binding in SQD1, a protein essential for sulfolipid biosynthesis in Arabidopsis.. Arch Biochem Biophys 369(1):30-41 PMID: 10462438
