GO:0070569 uridylyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0070569 (uridylyltransferase activity) describes enzymes that transfer a uridylyl group from a donor such as UTP to an acceptor molecule.
• The term covers both small-molecule sugar-1-phosphate uridylyltransferases, such as GalT and GlgC, and RNA uridylyltransferases that add uridine to RNA 3' ends.
• Galactose-1-phosphate uridylyltransferase (GALT) is the best-characterized human enzyme in this class and its deficiency causes classic galactosemia.
• Bacterial and plant sugar-1-phosphate uridylyltransferases are important for exopolysaccharide and starch/glycogen biosynthesis and are studied as antimicrobial or biotechnological targets.
• RNA uridylyltransferases such as CID1 and RET1/TRAMP components regulate RNA stability, mitochondrial RNA processing and small RNA pathways.
• CRISPR knockout, point-mutation, knock-in and overexpression models are widely used to dissect uridylyltransferase function in disease and metabolism.
Description
Uridylyltransferase activity (GO:0070569) is a molecular function defined as the catalysis of the transfer of a uridylyl group to an acceptor. The reaction is central to nucleotide sugar interconversion, RNA 3' end modification and several biosynthetic pathways in bacteria, plants and humans. Enzymes with this activity typically use UTP as the uridylyl donor and release pyrophosphate, generating a uridylylated product that can be a sugar-1-phosphate, a protein or an RNA molecule. Because the term is broad, it encompasses both metabolic enzymes such as glucose-1-phosphate uridylyltransferase and galactose-1-phosphate uridylyltransferase, and nucleic-acid-modifying enzymes such as RNA uridylyltransferases. Researchers care about GO:0070569 because defects in these enzymes cause human disease and because the activity is a validated target in microbial and plant systems. In humans, loss-of-function variants in GALT cause classic galactosemia, a disorder of galactose metabolism with severe neonatal and long-term complications. In bacteria, glucose-1-phosphate uridylyltransferase from Erwinia amylovora contributes to exopolysaccharide synthesis and is a potential target for fire blight control. In RNA biology, uridylyltransferases modify RNA ends and participate in mitochondrial RNA processing and small RNA pathways. This article summarizes the QuickGO definition, the catalytic and structural features of uridylyltransferases, the key genes and proteins, disease links and the experimental methods, including CRISPR-based models, used to study this activity.
uridylyltransferase activity At A Glance
| GO ID | GO:0070569 |
|---|---|
| GO term | uridylyltransferase activity |
| Ontology | molecular_function |
| Synonym | uridyl transferase activity; uridyltransferase activity |
| Definition | Catalysis of the transfer of an uridylyl group to an acceptor |
| Major function | Transfer of a uridylyl group from UTP or another donor to a sugar, protein or RNA acceptor |
| Representative enzymes | Galactose-1-phosphate uridylyltransferase (GALT), glucose-1-phosphate uridylyltransferase (GlgC), RNA uridylyltransferases such as CID1 and RET1 |
| Common donors | UTP, sometimes UDP-sugars |
| Common acceptors | Galactose-1-phosphate, glucose-1-phosphate, RNA 3' ends, protein substrates |
| Disease relevance | Classic galactosemia (GALT deficiency), bacterial virulence, RNA processing defects |
What Is GO:0070569?
In simple terms, uridylyltransferase activity means an enzyme takes a uridylyl group (UMP-like unit) from a donor molecule and attaches it to another molecule. The QuickGO definition states that GO:0070569 is the catalysis of the transfer of an uridylyl group to an acceptor. The donor is usually UTP, and the acceptor can be a sugar-1-phosphate, a protein or an RNA end. The reaction often releases pyrophosphate and is reversible in some metabolic contexts. Synonyms include uridyl transferase activity and uridyltransferase activity. The term is a molecular_function term and should not be confused with related activities such as nucleotidyltransferase activity in general, which transfers any nucleotide, or with uridylyl removal enzymes.
Why Is uridylyltransferase activity Important in Cell Biology?
Uridylyltransferase activity is important because it sits at the intersection of carbohydrate metabolism, RNA processing and microbial pathogenesis. In humans, GALT is the second enzyme of the Leloir pathway and its deficiency causes classic galactosemia, a disease with life-threatening neonatal symptoms and long-term cognitive and reproductive complications. In bacteria, glucose-1-phosphate uridylyltransferase is required for exopolysaccharide biosynthesis and contributes to virulence of plant and animal pathogens. In RNA biology, uridylyltransferases add uridine to RNA 3' ends and regulate RNA stability, mitochondrial RNA maturation and small RNA pathways. Because the activity is chemically simple but biologically versatile, it is a useful model for studying enzyme mechanism, substrate specificity and the impact of point mutations on catalysis.
• Defines a core enzymatic step in galactose metabolism through GALT.
• Causes classic galactosemia when GALT is deficient, a disease with neonatal and long-term complications.
• Supports bacterial exopolysaccharide biosynthesis and virulence in pathogens such as Erwinia amylovora.
• Contributes to starch and glycogen biosynthesis in plants and bacteria through glucose-1-phosphate uridylyltransferases.
• Regulates RNA stability and processing through RNA uridylyltransferases.
• Provides a target for pharmacochaperone and small-molecule therapy in galactosemia.
• Offers a model system for studying enzyme mechanism, substrate specificity and point mutations.
• Enables CRISPR-based disease modeling of GALT and related genes.
• Connects metabolic flux to nucleotide sugar pools and glycosylation.
• Is relevant to antimicrobial and biotechnological strategies targeting bacterial uridylyltransferases.
What Happens During uridylyltransferase activity?
Substrate recognition and donor binding
In simple terms: The enzyme first grabs the uridylyl donor, usually UTP, and the acceptor molecule.
Uridylyltransferases bind UTP or a related UDP-sugar donor and the acceptor substrate in an ordered or random fashion depending on the enzyme. In galactose-1-phosphate uridylyltransferase, the donor is UDP-glucose and the acceptor is galactose-1-phosphate, and the enzyme uses a ping-pong or sequential mechanism depending on the organism. In glucose-1-phosphate uridylyltransferase from Erwinia amylovora, the enzyme uses UTP and glucose-1-phosphate and shows strict specificity for the sugar-1-phosphate acceptor. RNA uridylyltransferases instead bind UTP and an RNA 3' end, often without a separate sugar acceptor.
Uridylyl transfer and product formation
In simple terms: The uridylyl group is moved from the donor to the acceptor, forming a new product.
During catalysis, the uridylyl group is transferred to the acceptor, releasing pyrophosphate or UDP depending on the donor. For GALT, the reaction converts galactose-1-phosphate and UDP-glucose to glucose-1-phosphate and UDP-galactose, which then enters the Leloir pathway. For GlgC, the product is ADP-glucose or UDP-glucose, a precursor for starch or glycogen. For RNA uridylyltransferases, the product is an RNA with an added uridine at its 3' end, which can alter RNA stability or processing.
Structural basis of catalysis
In simple terms: The enzyme uses a specific pocket and conserved residues to position the donor and acceptor for reaction.
Crystal structures of sugar-1-phosphate uridylyltransferases show a conserved fold with a central beta-sheet and a nucleotide-binding pocket. In GALT, the active site contains a conserved histidine and other residues that coordinate the phosphate groups and stabilize the transition state. Human GALT functions as a homodimer or heterodimer, and dimer formation is required for activity. Mutations that disrupt the active site or dimer interface reduce catalytic efficiency and cause galactosemia.
Regulation and cellular context
In simple terms: The activity is controlled by substrate availability, protein interactions and cellular signals.
Uridylyltransferase activity is regulated by substrate availability, product inhibition and protein-protein interactions. In galactosemia, residual GALT activity and the availability of UDP-glucose influence metabolic flux. Pharmacochaperones can stabilize mutant GALT and improve its activity, showing that folding and stability regulate the enzyme in cells. In bacteria, expression of GlgC and related enzymes is controlled by carbon source and stress signals. RNA uridylyltransferases are regulated by their association with other proteins in RNA processing complexes.
Physiological consequences
In simple terms: The reaction affects sugar metabolism, RNA fate and cell function.
Loss of GALT activity leads to accumulation of galactose-1-phosphate and galactitol, which are toxic to cells and cause the clinical features of classic galactosemia. In bacteria, loss of glucose-1-phosphate uridylyltransferase reduces exopolysaccharide production and virulence. In RNA metabolism, loss of uridylyltransferase activity alters RNA stability and mitochondrial RNA processing. These consequences make the activity a focal point for disease modeling and drug development.
Key Genes Involved in GO:0070569 uridylyltransferase activity
The following genes and proteins represent the main uridylyltransferases and related factors discussed in the literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| GALT | Galactose-1-phosphate uridylyltransferase; converts galactose-1-phosphate to glucose-1-phosphate | Causes classic galactosemia; target of pharmacochaperones and gene editing |
| GlgC | Glucose-1-phosphate uridylyltransferase; produces ADP-glucose for glycogen/starch | Bacterial and plant starch/glycogen biosynthesis; antimicrobial target |
| CID1 | RNA uridylyltransferase; adds uridine to RNA 3' ends | Regulates RNA stability and small RNA pathways |
| RET1 | RNA uridylyltransferase involved in mitochondrial RNA processing | Mitochondrial RNA metabolism and disease models |
| UAP1 | UDP-N-acetylglucosamine pyrophosphorylase; related uridylyltransferase | Glycosylation and metabolic studies |
| UGP2 | UDP-glucose pyrophosphorylase; produces UDP-glucose | Glycogen and glycosylation research |
| GALE | UDP-galactose-4-epimerase; works with GALT in Leloir pathway | Galactosemia and metabolic disease models |
| GALK1 | Galactokinase; upstream of GALT | Galactosemia and cataract research |
| PAPSS1 | Sulfate adenylyltransferase; related nucleotide transfer | Comparative enzymology |
| TUT1 | Terminal uridylyltransferase; RNA uridylation | RNA stability and cancer biology |
| TUT4 | Terminal uridylyltransferase; RNA uridylation | Let-7 and stem cell regulation |
| TUT7 | Terminal uridylyltransferase; RNA uridylation | RNA decay and development |
| ZCCHC11 | RNA uridylyltransferase | Small RNA regulation |
| MTPAP | Mitochondrial poly(A) polymerase; related nucleotidyl transfer | Mitochondrial RNA processing |
| PAPD5 | Non-canonical poly(A) polymerase; related activity | RNA processing and disease |
| GALT2 | Plant galactose-1-phosphate uridylyltransferase | Plant cell wall and galactose metabolism |
| GlgA | Glycogen synthase; downstream of GlgC | Glycogen biosynthesis studies |
| GlgP | Glycogen phosphorylase; glycogen metabolism | Metabolic flux studies |
How Is uridylyltransferase activity Regulated?
Uridylyltransferase activity is regulated at multiple levels. Substrate availability, especially UTP and sugar-1-phosphate pools, directly controls flux through these enzymes. In galactosemia, residual GALT activity and UDP-glucose levels influence the severity of metabolic dysfunction. Protein folding and stability regulate GALT, and pharmacochaperones can improve mutant enzyme activity by stabilizing the protein. In bacteria, expression of glucose-1-phosphate uridylyltransferase is controlled by carbon source and stress signals. RNA uridylyltransferases are regulated by their association with RNA processing complexes and by post-translational modifications. These layers of regulation make the activity responsive to cellular metabolic state and stress.
uridylyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| GALT | Classic galactosemia | GALT knockout or point-mutation cell models; patient-derived fibroblasts |
| GlgC | Bacterial exopolysaccharide synthesis and virulence | Bacterial knockout and complementation models |
| CID1 | RNA stability and small RNA pathways | RNA uridylyltransferase knockout cells with RNA-seq |
| RET1 | Mitochondrial RNA processing | Knockout cells with mitochondrial RNA analysis |
| GALE | Galactosemia and metabolic disease | Knockout and knock-in models for Leloir pathway studies |
Classic galactosemia
Classic galactosemia is an autosomal recessive disorder caused by loss-of-function variants in GALT, which encodes galactose-1-phosphate uridylyltransferase. Affected infants present with jaundice, vomiting, hepatomegaly and failure to thrive after galactose ingestion, and long-term complications include cognitive impairment, speech deficits and premature ovarian insufficiency. The disease is diagnosed by newborn screening and confirmed by enzyme activity assays and genetic testing. Current treatment is a galactose-restricted diet, but it does not prevent all long-term complications, motivating research into pharmacochaperones and gene-based therapies.
Bacterial virulence and exopolysaccharide biosynthesis
Glucose-1-phosphate uridylyltransferase from Erwinia amylovora is required for exopolysaccharide synthesis, which contributes to biofilm formation and fire blight disease in plants. The enzyme uses UTP and glucose-1-phosphate and shows strict substrate specificity, making it a potential target for antimicrobial or anti-virulence strategies. Structural studies of this enzyme provide a basis for inhibitor design.
RNA uridylylation and RNA processing disorders
RNA uridylyltransferases add uridine to RNA 3' ends and regulate RNA stability, mitochondrial RNA processing and small RNA pathways. Dysregulation of these enzymes has been linked to altered RNA metabolism in cancer and developmental disorders, although the precise disease mechanisms remain under investigation. Model systems such as knockout cells and RNA sequencing are used to study these effects.
From uridylyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of GALT cause metabolic dysfunction? | GALT knockout cell line or organoid |
| Can a point mutation in GALT be rescued by pharmacochaperones? | GALT point-mutation knock-in cells |
| What is the effect of uridylyltransferase overexpression on RNA stability? | Overexpression cell line with RNA-seq |
| How does GlgC contribute to bacterial virulence? | Bacterial knockout and plant infection model |
| What proteins interact with GALT? | Tagged knock-in with affinity purification and proteomics |
| How does GALT deficiency affect glycosylation? | Knockout cells with glycomics and metabolomics |
How to Study the uridylyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Coupled enzyme assay | Uridylyltransferase activity and kinetics | GALT and GlgC characterization |
| X-ray crystallography | Three-dimensional structure of enzyme-substrate complexes | Active-site and substrate specificity studies |
| RNA-seq | Transcript abundance and 3' end modifications | RNA uridylyltransferase function |
| Ribo-seq | Translation efficiency and ribosome occupancy | Effects of RNA uridylylation on translation |
| Affinity purification-mass spectrometry | Protein-protein interactions | GALT dimer and complex analysis |
| Metabolomics | Sugar-1-phosphate and nucleotide sugar levels | Galactosemia and metabolic flux studies |
| Site-directed mutagenesis | Effect of point mutations on activity | Structure-function analysis |
| CRISPR screening | Genes required for uridylyltransferase-dependent phenotypes | Pathway discovery and drug target identification |
Enzyme activity assays
Uridylyltransferase activity is measured using coupled enzyme assays that monitor the formation of UDP-sugars or the release of pyrophosphate. For GALT, assays use galactose-1-phosphate and UDP-glucose and detect glucose-1-phosphate or UDP-galactose. For GlgC, assays use UTP and glucose-1-phosphate and measure UDP-glucose formation. These assays are used to determine kinetic parameters and to test the effect of mutations or inhibitors.
Structural biology
X-ray crystallography and cryo-electron microscopy provide atomic models of uridylyltransferases bound to substrates or inhibitors. Structures of GALT and GlgC reveal conserved folds and active-site residues that are important for catalysis and substrate specificity. These structures guide the design of point mutations and small-molecule modulators.
RNA sequencing and Ribo-seq
RNA-seq and Ribo-seq are used to study the impact of RNA uridylyltransferases on transcript stability and translation. Knockout or knockdown of enzymes such as CID1 or RET1 followed by RNA-seq reveals changes in RNA abundance and 3' end modification. These methods are also used to study how uridylylation affects small RNA pathways.
Proteomics and interactomics
Affinity purification coupled to mass spectrometry identifies proteins that interact with uridylyltransferases and their complexes. For GALT, interactomics can reveal dimer partners and chaperones that regulate activity. For RNA uridylyltransferases, proteomics identifies components of RNA processing complexes.
How CRISPR Can Be Used to Study GO:0070569 uridylyltransferase activity
Knockout
CRISPR knockout of GALT or other uridylyltransferase genes creates cell models that lack the activity and mimic disease states. These models are used to study metabolic consequences, such as galactose-1-phosphate accumulation, and to test rescue strategies. Knockout of bacterial GlgC is used to study exopolysaccharide production and virulence.
Point Mutation
CRISPR point-mutation knock-in introduces disease-associated variants, such as GALT mutations found in galactosemia patients, into cell lines. These models allow researchers to test the effect of specific mutations on enzyme activity and stability and to evaluate pharmacochaperones that may restore function.
Knock-in
Knock-in of tagged versions of uridylyltransferases, such as GFP- or FLAG-tagged GALT, enables imaging and interactomics studies. Knock-in of reporter cassettes can also be used to monitor enzyme expression and localization in live cells.
Overexpression
Overexpression of uridylyltransferases is used to study gain-of-function effects, substrate channeling and RNA modification. Overexpression models help determine whether increased activity alters metabolic flux or RNA stability and can be combined with RNA-seq or metabolomics.
How EDITGENE Supports uridylyltransferase activity Research
Researchers studying uridylyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in a metabolic or RNA-processing phenotype. This requires precise, reproducible cell models that can isolate the contribution of a single gene or mutation. EDITGENE provides a suite of CRISPR-based services designed to support such studies, from knockout to knock-in and library screening.
Contact EDITGENE today to design your custom CRISPR model for uridylyltransferase activity research.
Frequently Asked Questions About uridylyltransferase activity
What is uridylyltransferase activity?
Uridylyltransferase activity (GO:0070569) is the catalysis of the transfer of a uridylyl group to an acceptor, typically using UTP as the donor.
What genes are involved in uridylyltransferase activity?
Key genes include GALT, GlgC, CID1, RET1, UAP1, UGP2 and TUT1, among others.
What diseases are linked to uridylyltransferase activity?
Classic galactosemia is caused by GALT deficiency, and bacterial GlgC contributes to virulence; RNA uridylyltransferases are linked to RNA processing disorders.
What is the GO ID for uridylyltransferase activity?
The GO ID is GO:0070569.
What is the difference between uridylyltransferase and nucleotidyltransferase?
Uridylyltransferase specifically transfers a uridylyl group, whereas nucleotidyltransferase can transfer any nucleotide.
How is uridylyltransferase activity measured?
It is measured using coupled enzyme assays that detect UDP-sugar formation or pyrophosphate release.
What is the role of GALT in galactosemia?
GALT converts galactose-1-phosphate to glucose-1-phosphate, and its deficiency causes classic galactosemia.
Can CRISPR be used to study uridylyltransferase genes?
Yes, CRISPR knockout, point-mutation, knock-in and overexpression models are widely used to study these genes.
What are RNA uridylyltransferases?
They are enzymes that add uridine to RNA 3' ends and regulate RNA stability and processing.
What model systems are used for uridylyltransferase research?
Common models include knockout cell lines, patient-derived fibroblasts, bacterial strains and CRISPR knock-in cells.
Conclusion
Uridylyltransferase activity (GO:0070569) is a fundamental molecular function that connects nucleotide sugar metabolism, RNA modification and microbial pathogenesis. The best-characterized human enzyme, GALT, is directly linked to classic galactosemia, while bacterial and RNA uridylyltransferases are important for virulence and RNA processing. Understanding the mechanism, regulation and disease relevance of these enzymes requires precise experimental models, and CRISPR-based approaches are now central to this effort. Continued research into uridylyltransferases promises new insights into metabolic disease and RNA biology.
References
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- 2. Scafuri B et al.. 2025. Improvement of Mutant Galactose-1-Phosphate Uridylyltransferase (GALT) Activity by FDA-Approved Pharmacochaperones: A Preliminary Study.. Int J Mol Sci 26(3) PMID: 39940658
- 3. Aphasizhev R. 2005. RNA uridylyltransferases.. Cell Mol Life Sci 62(19-20):2194-203 PMID: 16158189
- 4. McCorvie TJ et al.. 2011. The structural and molecular biology of type I galactosemia: Enzymology of galactose 1-phosphate uridylyltransferase.. IUBMB Life 63(9):694-700 PMID: 21793161
- 5. Delnoy B et al.. 2021. Current and Future Treatments for Classic Galactosemia.. J Pers Med 11(2) PMID: 33525536
- 6. Timson DJ. 2020. Therapies for galactosemia: a patent landscape.. Pharm Pat Anal 9(2):45-51 PMID: 32314655
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