GO:0019787 ubiquitin-like protein transferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0019787 (ubiquitin-like protein transferase activity) describes the catalysis of transferring a ubiquitin-like protein (ULP) from one protein to another, forming a covalent linkage.
• This activity is carried out by E2 conjugating enzymes and E3 ligases, which together attach UBLs such as ubiquitin, SUMO, and Urm1 to substrates.
• Phosphorylation of ubiquitin at Ser65 by PINK1 activates Parkin E3 ligase, linking ubiquitin-like transfer to mitophagy and neurodegeneration.
• TRIM21-mediated ubiquitination of G3BP1 regulates stress granule homeostasis and autophagy, illustrating the role of UBL transfer in cellular stress responses.
• SUMO-2/3 modification of NSUN2 promotes gastric cancer progression and modulates mRNA m5C methylation, highlighting disease relevance.
• CRISPR-based knockout, point mutation, knock-in, and overexpression models enable precise dissection of UBL transferase functions in health and disease.
Description
Ubiquitin-like protein transferase activity (GO:0019787) is a molecular function that catalyzes the transfer of a ubiquitin-like protein (ULP) from one protein to another via a covalent linkage. This activity is fundamental to post-translational modification systems that regulate protein stability, localization, and interactions. The ULP family includes ubiquitin, SUMO, NEDD8, ISG15, and Urm1, each conjugated to targets by dedicated enzymatic cascades. The transfer reaction typically involves E1 activating enzymes, E2 conjugating enzymes, and E3 ligases, which together ensure substrate specificity. Researchers study GO:0019787 because dysregulation of UBL transfer is implicated in cancer, neurodegeneration, and immune disorders. For example, PINK1 phosphorylates ubiquitin to activate Parkin E3 ligase, a key step in mitophagy, and mutations in this pathway cause early-onset Parkinson's disease. Similarly, TRIM21-mediated ubiquitination of G3BP1 controls stress granule dynamics and autophagy, linking UBL transfer to cellular stress responses. Understanding the molecular mechanisms and regulatory networks of UBL transferases is therefore essential for developing targeted therapies. This article provides a comprehensive overview of GO:0019787, covering its definition, biological significance, key genes, regulatory mechanisms, disease associations, and experimental models. It is designed for researchers seeking to investigate UBL transferases using CRISPR-based approaches and other advanced methodologies.
ubiquitin-like protein transferase activity At A Glance
| GO ID | GO:0019787 |
|---|---|
| GO term | ubiquitin-like protein transferase activity |
| Ontology | molecular_function |
| Synonym | E2, E3, small conjugating protein ligase activity, small conjugating protein transferase activity, small protein conjugating enzyme activity, ubiquitin-like conjugating enzyme activity, ubiquitin-like-protein ligase activity |
| Major function | Catalyzes the covalent attachment of ubiquitin-like proteins to target proteins |
| Reaction | X-ULP + Y = Y-ULP + X, where ULP is a ubiquitin-like protein |
| Related enzymes | E1 activating enzymes, E2 conjugating enzymes, E3 ligases |
| Substrates | Ubiquitin, SUMO, NEDD8, ISG15, Urm1, and other UBLs |
What Is GO:0019787?
GO:0019787, ubiquitin-like protein transferase activity, is defined as the catalysis of the transfer of a ubiquitin-like protein (ULP) from one protein to another via the reaction X-ULP + Y = Y-ULP + X, where both X-ULP and Y-ULP are covalent linkages. In simpler terms, it is the enzymatic activity that attaches a small protein tag (like ubiquitin or SUMO) onto a target protein. This activity is mediated by E2 conjugating enzymes and E3 ligases, which work together to recognize substrates and facilitate the covalent attachment of ULP molecules.
Why Is ubiquitin-like protein transferase activity Important in Cell Biology?
Ubiquitin-like protein transferase activity is essential for virtually all cellular processes, including protein degradation, DNA repair, cell cycle progression, and immune signaling. Dysregulation of this activity leads to a wide range of diseases, from cancer to neurodegeneration. For instance, PINK1-mediated phosphorylation of ubiquitin activates Parkin, a process critical for mitochondrial quality control; defects in this pathway are linked to Parkinson's disease. Moreover, SUMOylation of NSUN2 by SUMO-2/3 promotes gastric cancer progression, demonstrating the oncogenic potential of UBL transfer. Understanding the mechanisms and regulation of UBL transferases is therefore crucial for identifying therapeutic targets and developing precision medicine strategies.
• Regulates protein stability and degradation via the ubiquitin-proteasome system.
• Controls subcellular localization and activity of key signaling proteins.
• Mediates stress granule dynamics and autophagy through TRIM21-mediated ubiquitination of G3BP1.
• Activates Parkin E3 ligase via PINK1-dependent ubiquitin phosphorylation, impacting mitophagy.
• Modulates NF-kB signaling through phosphorylation and ubiquitination events.
• Promotes cancer progression via SUMOylation of NSUN2 and mRNA m5C methylation.
• Involved in the regulation of autophagy by reactive oxygen species.
• Urm1, a non-canonical UBL, plays roles in oxidative stress response and tRNA modification.
• Dysregulation is associated with neurodegenerative diseases, including Parkinson's disease.
• Provides targets for CRISPR-based functional studies and drug discovery.
What Happens During ubiquitin-like protein transferase activity?
Activation of Ubiquitin-Like Proteins
In simple terms: First, the small tag protein is activated by an E1 enzyme using energy from ATP.
The transfer of ubiquitin-like proteins (ULPs) begins with the ATP-dependent activation of the ULP by an E1 activating enzyme. This step forms a thioester bond between the C-terminus of the ULP and a cysteine residue in the E1 enzyme. For ubiquitin, this activation is a prerequisite for subsequent conjugation steps. In the case of Urm1, a non-canonical UBL, activation also involves E1-like enzymes, although the machinery is distinct from canonical ubiquitin.
Conjugation by E2 Enzymes
In simple terms: The activated tag is then passed to an E2 enzyme, which acts as a carrier.
The activated ULP is transferred from the E1 enzyme to an E2 conjugating enzyme through a trans-thioesterification reaction. The E2 enzyme forms a thioester bond with the ULP and serves as the central hub for the transferase activity. E2 enzymes are characterized by a conserved catalytic core domain and determine the type of ULP and the linkage specificity. For example, PINK1 phosphorylates ubiquitin at Ser65, which is required for efficient transfer to Parkin, an E3 ligase, by the E2 enzyme UBE2L3.
Substrate Recognition and Ligation by E3 Ligases
In simple terms: Finally, an E3 ligase helps attach the tag to the correct target protein.
E3 ligases bind both the E2-ULP complex and the target substrate, facilitating the transfer of the ULP to a lysine residue on the substrate. This step confers substrate specificity and is tightly regulated. For instance, Parkin, an E3 ligase, is activated by PINK1-mediated phosphorylation of ubiquitin and subsequently ubiquitinates outer mitochondrial membrane proteins to trigger mitophagy. Similarly, TRIM21 acts as an E3 ligase for G3BP1, promoting its ubiquitination and autophagic degradation.
Regulation by Phosphorylation and Other Modifications
In simple terms: The activity of these enzymes can be turned on or off by adding phosphate groups or other modifications.
Phosphorylation plays a critical role in regulating UBL transferase activity. PINK1 phosphorylates ubiquitin at Ser65, which enhances Parkin E3 ligase activity and promotes mitophagy. Additionally, SUMOylation of NSUN2 by SUMO-2/3 modulates its function in mRNA m5C methylation and gastric cancer progression. Reactive oxygen species (ROS) also regulate autophagy through modulation of UBL transfer systems.
Deconjugation and Recycling
In simple terms: Tags can be removed by specific enzymes to reverse the modification.
Deubiquitinating enzymes (DUBs) and UBL-specific proteases remove UBLs from substrates, ensuring reversibility and dynamic regulation. This step is essential for maintaining free ULP pools and preventing aberrant accumulation. For example, the removal of ubiquitin from G3BP1 by DUBs may affect stress granule disassembly.
Key Genes Involved in GO:0019787 ubiquitin-like protein transferase activity
The following genes encode key enzymes and substrates involved in ubiquitin-like protein transferase activity, including E1, E2, E3 enzymes, and UBLs themselves.
| Gene | Major Role | Research Relevance |
|---|---|---|
| UBE2L3 | E2 conjugating enzyme | Works with Parkin in mitophagy; implicated in Parkinson's disease |
| PINK1 | Ser/Thr kinase that phosphorylates ubiquitin | Activates Parkin; mutations cause early-onset Parkinson's disease |
| PRKN (Parkin) | E3 ubiquitin ligase | Mediates mitophagy; mutations linked to Parkinson's disease |
| TRIM21 | E3 ubiquitin ligase | Ubiquitinates G3BP1 to regulate stress granules and autophagy |
| G3BP1 | Substrate of TRIM21 | Stress granule assembly; ubiquitination affects autophagy |
| NSUN2 | RNA methyltransferase | SUMOylated by SUMO-2/3; promotes gastric cancer progression |
| SUMO2 | Ubiquitin-like protein | Modifies NSUN2 and other substrates |
| SUMO3 | Ubiquitin-like protein | Modifies NSUN2 and other substrates |
| URM1 | Non-canonical UBL | Involved in oxidative stress response and tRNA modification |
| UBA1 | E1 activating enzyme for ubiquitin | Initiates ubiquitin activation |
| UBA2 | E1 activating enzyme for SUMO | Activates SUMO for conjugation |
| UBE2I (UBC9) | E2 conjugating enzyme for SUMO | Conjugates SUMO to targets |
| NEDD8 | Ubiquitin-like protein | Modifies cullin proteins to regulate CRLs |
| ISG15 | Ubiquitin-like protein | Plays roles in antiviral immunity |
| ATG7 | E1-like enzyme for ATG8/LC3 | Essential for autophagy |
| ATG3 | E2-like enzyme for ATG8/LC3 | Conjugates LC3 to phosphatidylethanolamine |
| NFKB1 | Transcription factor | Regulated by ubiquitination and phosphorylation |
How Is ubiquitin-like protein transferase activity Regulated?
Ubiquitin-like protein transferase activity is regulated at multiple levels, including enzyme expression, post-translational modifications, and availability of substrates. Phosphorylation of ubiquitin by PINK1 is a key regulatory event that activates Parkin E3 ligase and promotes mitophagy. SUMOylation of NSUN2 by SUMO-2/3 modulates its function in mRNA methylation and cancer progression. Reactive oxygen species (ROS) regulate autophagy by influencing UBL transfer systems, including ATG7 and ATG3. Additionally, NF-kB signaling is controlled by phosphorylation and ubiquitination events that involve UBL transferases. These regulatory mechanisms ensure precise spatiotemporal control of UBL conjugation.
ubiquitin-like protein transferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PINK1 | Parkinson's disease | Knockout and point-mutation knock-in in neuronal cells |
| PRKN | Parkinson's disease | Knockout and overexpression in SH-SY5Y cells |
| NSUN2 | Gastric cancer | Knockout and SUMOylation-site point mutant in gastric cancer cell lines |
| TRIM21 | Stress granule regulation, autoimmunity | Knockout and tagged knock-in in HeLa cells |
| G3BP1 | Stress granule dynamics, cancer | Knockout and ubiquitination-site mutant in cancer cells |
Neurodegeneration: Parkinson's Disease
Mutations in PINK1 and PRKN (Parkin) cause early-onset Parkinson's disease. PINK1 phosphorylates ubiquitin at Ser65, which activates Parkin's E3 ligase activity, leading to mitophagy. Defects in this pathway result in mitochondrial dysfunction and neuronal death. Small molecules that act as molecular glues to activate Parkin are being explored as therapeutic strategies.
Cancer: Gastric Cancer and Beyond
SUMOylation of NSUN2 by SUMO-2/3 promotes gastric cancer progression by regulating mRNA m5C methylation. TRIM21-mediated ubiquitination of G3BP1 affects stress granule dynamics and autophagy, which can influence cancer cell survival under stress. Dysregulation of UBL transferases is increasingly recognized as a hallmark of various cancers.
Inflammation and Immune Signaling
NF-kB activation requires phosphorylation and ubiquitination of IkB and other signaling components. UBL transferases, including E3 ligases, are critical for the degradation of IkB and the nuclear translocation of NF-kB, thereby controlling inflammatory responses.
Autophagy and Stress Responses
ROS regulate autophagy through UBL transfer systems, including the ATG7-ATG3 conjugation cascade that lipidates LC3. TRIM21-mediated ubiquitination of G3BP1 links stress granule homeostasis to autophagy, impacting cell survival under stress.
From ubiquitin-like protein transferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of PINK1 affect mitophagy? | PINK1 knockout cell lines (e.g., HeLa, SH-SY5Y) |
| How does Ser65 phosphorylation of ubiquitin regulate Parkin? | Point mutation (S65A) knock-in of ubiquitin in cells |
| What is the role of TRIM21 in stress granule clearance? | TRIM21 knockout and overexpression models |
| Does SUMOylation of NSUN2 promote cancer? | NSUN2 SUMOylation-site mutant knock-in in gastric cancer cells |
| Can a molecular glue activate Parkin? | Parkin knock-in with tagged ubiquitin and small molecule treatment |
| What is the interactome of UBE2L3? | Tagged knock-in of UBE2L3 followed by AP-MS |
How to Study the ubiquitin-like protein transferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| DiGly proteomics | Ubiquitinated peptides | Global profiling of ubiquitination sites |
| Phosphoproteomics | Phosphorylated peptides | Identifying PINK1 substrates and signaling |
| Live-cell imaging | Fluorescently tagged proteins | Monitoring stress granule and autophagosome dynamics |
| CRISPR knockout screens | Gene essentiality and pathway regulators | Discovering novel UBL transfer components |
| Co-immunoprecipitation | Protein-protein interactions | Identifying E3-substrate complexes |
| In vitro ubiquitination assays | Enzymatic activity | Measuring E2/E3 activity with recombinant proteins |
| SUMOylation assays | SUMO conjugation | Detecting SUMO-modified substrates like NSUN2 |
Proteomics and Ubiquitinome Analysis
Mass spectrometry-based proteomics can identify ubiquitinated substrates and map ubiquitination sites. Techniques such as diGly enrichment followed by LC-MS/MS enable global profiling of ubiquitin-like modifications. This is useful for studying the substrates of specific E3 ligases like Parkin and TRIM21.
Phosphoproteomics
Phosphoproteomics can reveal signaling events that regulate UBL transferase activity, such as PINK1-mediated phosphorylation of ubiquitin at Ser65. This approach helps identify kinase-substrate relationships and crosstalk between phosphorylation and ubiquitination.
Live-Cell Imaging
Fluorescently tagged UBLs and substrates allow real-time visualization of conjugation and deconjugation. For example, GFP-tagged LC3 is used to monitor autophagosome formation, while mCherry-G3BP1 can track stress granule dynamics upon TRIM21-mediated ubiquitination.
CRISPR Screens
Genome-wide CRISPR knockout screens can identify genes required for UBL transfer pathways. For instance, screens for regulators of mitophagy have uncovered components of the PINK1-Parkin pathway.
How CRISPR Can Be Used to Study GO:0019787 ubiquitin-like protein transferase activity
Knockout
CRISPR knockout of genes encoding UBL transferases (e.g., PINK1, PRKN, TRIM21) allows researchers to assess loss-of-function phenotypes. For example, PINK1 knockout cells exhibit impaired mitophagy and accumulation of damaged mitochondria. Knockout of TRIM21 leads to altered stress granule clearance.
Point Mutation
Point mutations can be introduced to study specific residues critical for UBL transfer. For instance, mutating ubiquitin at Ser65 to alanine (S65A) prevents PINK1-mediated phosphorylation and blocks Parkin activation. Similarly, mutating the catalytic cysteine of an E2 enzyme abolishes its conjugating activity.
Knock-in
Knock-in of tagged UBLs (e.g., HA-ubiquitin) or substrates enables affinity purification and proteomic analysis. Knock-in of SUMOylation-site mutants of NSUN2 can reveal the functional impact of SUMO modification on mRNA methylation and cancer progression.
Overexpression
Overexpression of UBL transferases or their substrates can amplify signaling pathways. For example, overexpression of Parkin and PINK1 in cells enhances mitophagy and can be used to study activators or inhibitors. Overexpression of TRIM21 promotes G3BP1 ubiquitination and stress granule degradation.
How EDITGENE Supports ubiquitin-like protein transferase activity Research
Researchers studying ubiquitin-like protein transferase 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 enable precise genetic manipulation and functional interrogation of UBL transferases and their substrates.
Contact EDITGENE today to design your custom CRISPR model for ubiquitin-like protein transferase activity research.
Frequently Asked Questions About ubiquitin-like protein transferase activity
What is ubiquitin-like protein transferase activity?
It is the enzymatic activity that transfers a ubiquitin-like protein (ULP) from one protein to another via a covalent linkage, as defined by GO:0019787.
What genes are involved in ubiquitin-like protein transferase activity?
Key genes include E1 activating enzymes (UBA1, UBA2), E2 conjugating enzymes (UBE2L3, UBE2I), E3 ligases (PRKN, TRIM21), and UBLs (ubiquitin, SUMO2/3, URM1).
How is ubiquitin-like protein transferase activity regulated?
It is regulated by phosphorylation (e.g., PINK1-mediated ubiquitin phosphorylation), SUMOylation, and reactive oxygen species.
What diseases are associated with defects in ubiquitin-like protein transferase activity?
Parkinson's disease (PINK1/PRKN mutations), gastric cancer (NSUN2 SUMOylation), and inflammatory disorders (NF-kB signaling).
What is the role of PINK1 in ubiquitin-like protein transfer?
PINK1 phosphorylates ubiquitin at Ser65, which activates Parkin E3 ligase and promotes mitophagy.
How does TRIM21 regulate stress granules?
TRIM21 ubiquitinates G3BP1, leading to autophagic degradation of stress granules.
What is Urm1?
Urm1 is a non-canonical ubiquitin-like protein involved in oxidative stress response and tRNA modification.
Can CRISPR be used to study ubiquitin-like protein transferase activity?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models enable precise functional studies of UBL transferases.
What methods are used to measure ubiquitin-like protein transferase activity?
Methods include diGly proteomics, phosphoproteomics, live-cell imaging, and in vitro ubiquitination assays.
How does SUMOylation of NSUN2 affect cancer?
SUMO-2/3 modification of NSUN2 promotes gastric cancer progression and regulates mRNA m5C methylation.
Conclusion
Ubiquitin-like protein transferase activity (GO:0019787) is a central molecular function that governs protein modification by ubiquitin and UBLs, impacting nearly every cellular process. Its dysregulation is linked to major human diseases, including Parkinson's disease and cancer. Advances in CRISPR-based models and proteomic technologies are accelerating our understanding of these enzymes and their substrates. EDITGENE's comprehensive services empower researchers to dissect UBL transfer pathways with precision and translate findings into therapeutic strategies.
References
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