GO:0061630 ubiquitin protein ligase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0061630 (ubiquitin protein ligase activity) describes the catalytic transfer of ubiquitin to a substrate protein, forming an isopeptide bond between the C-terminal glycine of ubiquitin and a lysine residue in the substrate.
• This activity is executed by E3 ubiquitin ligases, which include HECT-type, RING-type, and U-box families; HECT ligases form a thioester intermediate with ubiquitin before transferring it to the substrate.
• E3 ligases such as NEDD4, XIAP, and Nedd4-2 regulate diverse processes including proteasomal degradation, cell death, immunity, and stress granule dynamics.
• Dysregulation of ubiquitin protein ligase activity is linked to cancer, neurodegenerative diseases, and immune disorders, making these enzymes attractive therapeutic targets.
• Research methods to study GO:0061630 include activity-based probes, reconstitution assays, ubiquitination assays, and CRISPR-based knockout or knock-in models.
• EDITGENE provides CRISPR services including knockout, point mutation, knock-in, overexpression, and library screening to dissect ubiquitin ligase function in disease models.
Description
Ubiquitin protein ligase activity (GO:0061630) is a molecular function that catalyzes the covalent attachment of ubiquitin to substrate proteins, a key step in the ubiquitin-proteasome system. This modification, known as ubiquitination, regulates protein stability, localization, and interactions, and is essential for numerous cellular processes. The reaction involves the transfer of ubiquitin from an E2 enzyme to a substrate via an E3 ligase, forming an isopeptide bond between the C-terminal glycine of ubiquitin and the epsilon-amino group of a lysine residue in the substrate. E3 ligases are critical for substrate specificity and are implicated in a wide range of diseases, including cancer and neurodegeneration. Understanding the mechanisms and regulation of ubiquitin protein ligase activity is therefore of paramount importance for both basic research and therapeutic development.
ubiquitin protein ligase activity At A Glance
| GO ID | GO:0061630 |
|---|---|
| GO term | ubiquitin protein ligase activity |
| Ontology | molecular_function |
| Synonym | E3, ER-associated E3 ligase, protein ubiquitination activity, ubiquitin ligase activity |
| Major function | Catalysis of ubiquitin transfer to substrate proteins, forming isopeptide bonds |
| EC number | Not specified in QuickGO |
| Related activity | Ubiquitin-protein transferase activity (GO:0004842) |
| Substrates | Proteins with lysine residues, including caspases, ion channels, and signaling molecules |
| Cofactors | E1 ubiquitin-activating enzyme, E2 ubiquitin-conjugating enzyme, ATP, ubiquitin |
What Is GO:0061630?
Ubiquitin protein ligase activity (GO:0061630) is defined as the catalysis of ubiquitin transfer to a substrate protein via a reaction where X-ubiquitin (X being an E2 or E3 enzyme) reacts with a substrate (S) to form X and S-ubiquitin. The X-ubiquitin linkage is a thioester bond, while the S-ubiquitin linkage is an amide bond, typically an isopeptide bond between the C-terminal glycine of ubiquitin and the epsilon-amino group of a lysine residue in the substrate, or a peptide bond in linear ubiquitin chain extension.
Why Is ubiquitin protein ligase activity Important in Cell Biology?
Ubiquitin protein ligase activity is fundamental to cellular homeostasis, as it controls the degradation, trafficking, and activity of numerous proteins. Dysregulation of E3 ligases leads to the accumulation of damaged proteins or the inappropriate destruction of key regulators, contributing to diseases such as cancer, neurodegenerative disorders, and immune deficiencies. Moreover, E3 ligases are highly specific, making them promising drug targets. Understanding their activity is crucial for developing therapies that modulate ubiquitination pathways.
• Regulates protein degradation via the proteasome, affecting cell cycle, apoptosis, and signaling.
• Controls immune responses by targeting immune regulators for ubiquitination.
• Involved in DNA repair, transcription, and stress responses.
• Dysregulation linked to cancer: XIAP promotes caspase-3 degradation, enhancing anti-apoptotic effects.
• Implicated in neurodegeneration: impaired ubiquitination leads to protein aggregation.
• Plays a role in plant immunity through proteasome-associated HECT ligases.
• Modulates stress granule dynamics via Nedd4-2 under hyperosmotic stress.
• Therapeutic potential: E3 ligases as targets for small molecules and PROTACs.
• Essential for developmental processes and tissue homeostasis.
• Activity can be monitored using activity-based probes for drug discovery.
What Happens During ubiquitin protein ligase activity?
Activation of ubiquitin by E1
In simple terms: First, ubiquitin is activated by an E1 enzyme using ATP.
Ubiquitin is activated by the E1 ubiquitin-activating enzyme in an ATP-dependent manner, forming a thioester bond between the C-terminal glycine of ubiquitin and a cysteine residue in E1.
Transfer to E2 conjugating enzyme
In simple terms: The activated ubiquitin is then passed to an E2 enzyme.
The activated ubiquitin is transferred to an E2 ubiquitin-conjugating enzyme through a trans-thioesterification reaction, resulting in an E2-ubiquitin thioester intermediate.
Substrate recognition by E3 ligase
In simple terms: The E3 ligase recognizes and binds the target protein.
E3 ubiquitin ligases specifically bind to substrate proteins through protein-protein interaction domains, such as HECT, RING, or U-box domains, ensuring selective ubiquitination.
Transfer of ubiquitin to substrate
In simple terms: Ubiquitin is attached to the target protein, often at a lysine residue.
The E3 ligase catalyzes the transfer of ubiquitin from the E2 enzyme to the substrate, forming an isopeptide bond between the C-terminal glycine of ubiquitin and the epsilon-amino group of a lysine residue in the substrate. In HECT ligases, a thioester intermediate with ubiquitin is formed before transfer.
Formation of polyubiquitin chains
In simple terms: Multiple ubiquitin molecules can be linked to form chains.
Further ubiquitin molecules can be attached to the initial ubiquitin, forming polyubiquitin chains with different linkages (e.g., K48, K63) that dictate the fate of the substrate, such as proteasomal degradation or signaling.
Key Genes Involved in GO:0061630 ubiquitin protein ligase activity
The following genes encode E3 ubiquitin ligases or related proteins that exhibit ubiquitin protein ligase activity (GO:0061630) and are widely studied in biomedical research.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NEDD4 | HECT-type E3 ligase; regulates ion channels, receptors, and signaling proteins | Implicated in cancer, hypertension, and neurological disorders |
| XIAP | RING-type E3 ligase; inhibits apoptosis by targeting caspase-3 | Cancer therapy target; anti-apoptotic factor |
| Nedd4-2 | HECT-type E3 ligase; regulates ion channels and stress granule dynamics | Role in hyperosmotic stress and P-body localization |
| UBR5 | HECT-type E3 ligase; involved in DNA damage response | Potential tumor suppressor or oncogene |
| Parkin | RING-between-RING E3 ligase; mitophagy and mitochondrial quality control | Mutations cause Parkinson's disease |
| MDM2 | RING-type E3 ligase; targets p53 for degradation | Oncogene; target for cancer therapy |
| Cullin-RING ligases | Multisubunit E3 complexes; regulate cell cycle and signaling | Targets for anticancer drugs |
| ITCH | HECT-type E3 ligase; regulates immune signaling and differentiation | Involved in autoimmunity and cancer |
| SMURF1 | HECT-type E3 ligase; regulates TGF-beta signaling | Role in development and cancer |
| TRIM proteins | RING-type E3 ligases; diverse functions including antiviral immunity | Implicated in innate immunity and cancer |
| APC/C | Multisubunit E3 ligase; controls cell cycle progression | Dysregulated in cancer |
| SCF complex | Multisubunit E3 ligase; regulates cell cycle and transcription | Target for drug discovery |
| CHIP | U-box E3 ligase; protein quality control | Linked to neurodegeneration |
| HRD1 | ER-associated E3 ligase; ERAD pathway | Implicated in protein folding diseases |
| PARK2 | RING-type E3 ligase; mitophagy | Parkinson's disease |
| RNF43 | RING-type E3 ligase; regulates Wnt signaling | Colorectal cancer |
| ZNRF3 | RING-type E3 ligase; regulates Wnt signaling | Cancer and stem cell biology |
How Is ubiquitin protein ligase activity Regulated?
Ubiquitin protein ligase activity is tightly regulated at multiple levels. E3 ligases can be controlled by post-translational modifications, such as phosphorylation, which can alter their activity or substrate specificity. For example, the NEDD4 ligase is regulated by autoinhibition and intramolecular interactions that are relieved upon substrate binding or phosphorylation. Adaptor proteins, such as arrestin domain-containing proteins, can modulate E3 ligase activity through disordered insertions. Additionally, the availability of E2 enzymes and ubiquitin can influence ligase activity. Under stress conditions, such as hyperosmotic stress, Nedd4-2 promotes localization of DNMBP/Tuba to P-bodies, indicating regulation of ligase function in response to environmental cues.
ubiquitin protein ligase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| XIAP | Cancer (apoptosis resistance) | Knockout in cancer cell lines; xenograft models |
| Parkin (PARK2) | Parkinson's disease | Patient-derived iPSCs; knockout mice |
| MDM2 | Cancer (p53 inactivation) | Knock-in mice; organoids |
| Nedd4-2 | Hypertension, stress response | Knockout zebrafish; cell-based assays |
| NEDD4 | Cancer, neurological disorders | Conditional knockout mice; CRISPR screens |
Ubiquitin ligases in cancer
Dysregulation of E3 ubiquitin ligases is frequently observed in cancer. XIAP, a potent inhibitor of apoptosis, promotes the degradation of caspase-3, thereby enhancing cell survival and contributing to tumorigenesis. Overexpression of MDM2 leads to p53 degradation, impairing tumor suppression. Targeting E3 ligases with small molecules or PROTACs is a promising therapeutic strategy.
Neurodegenerative disorders
Impaired ubiquitin protein ligase activity contributes to the accumulation of toxic proteins in neurodegenerative diseases. Mutations in Parkin, an E3 ligase involved in mitophagy, cause early-onset Parkinson's disease. Similarly, dysfunction of CHIP and other quality-control ligases is linked to Alzheimer's and amyotrophic lateral sclerosis.
Immune and inflammatory diseases
E3 ligases regulate immune signaling pathways. The proteasome-associated HECT-type ligase is required for plant immunity, and its counterparts in mammals modulate NF-kB and interferon responses. Dysregulation can lead to autoimmunity or immunodeficiency.
From ubiquitin protein ligase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of E3 ligase affect substrate stability? | CRISPR knockout cell lines followed by western blot |
| How does a point mutation in the catalytic domain affect ligase activity? | Point mutation knock-in via CRISPR |
| Can a tagged ligase be used to identify substrates? | Knock-in of epitope tag (e.g., HA, FLAG) |
| What is the effect of ligase overexpression on signaling? | Overexpression via lentiviral transduction |
| Which genes modulate ligase activity in a genome-wide screen? | CRISPR library screening |
| Does a disease-associated mutation alter ligase function? | Patient-derived iPSCs with isogenic controls |
How to Study the ubiquitin protein ligase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Activity-based probe labeling | Active E3 ligase enzymes | Drug discovery, enzyme profiling |
| In vitro ubiquitination assay | Ubiquitin transfer to substrate | Substrate identification, kinetic analysis |
| CRISPR knockout screen | Genes affecting ligase activity or pathway | Functional genomics |
| Di-glycine remnant proteomics | Global ubiquitination sites | Mapping signaling networks |
| Western blot with ubiquitin antibodies | Substrate ubiquitination levels | Validation of ligase-substrate relationships |
| Immunoprecipitation-mass spectrometry | Ligase interaction partners | Substrate discovery |
| Fluorescence microscopy | Subcellular localization of ligases | Stress granule dynamics |
| RNA-seq | Transcriptional changes upon ligase perturbation | Pathway analysis |
Activity-based probes for E3 ligases
Activity-based probes (ABPs) are chemical tools that covalently label active E3 ligases, allowing detection and quantification of ligase activity in complex lysates. For example, a HECT ligase-ubiquitin complex can be reconstituted and analyzed using ABPs.
In vitro ubiquitination assays
Reconstituted ubiquitination assays with purified E1, E2, E3, ubiquitin, and substrate are used to measure ligase activity and identify specific substrates. These assays can be coupled with western blotting or mass spectrometry.
CRISPR-based screens
Genome-wide CRISPR knockout or activation screens can identify genes that regulate ubiquitin ligase activity or that are essential for ligase-mediated processes. Such screens have revealed modulators of drug response and disease pathways.
Proteomics and ubiquitin remnant profiling
Mass spectrometry-based proteomics, including di-glycine remnant profiling, enables global mapping of ubiquitination sites and quantification of changes in ubiquitin ligase activity upon genetic or pharmacological perturbations.
How CRISPR Can Be Used to Study GO:0061630 ubiquitin protein ligase activity
Knockout
CRISPR knockout of an E3 ligase gene (e.g., NEDD4, XIAP) abolishes its activity, allowing researchers to study loss-of-function phenotypes, such as substrate accumulation or altered signaling. Knockout cell lines are valuable for validating ligase-substrate relationships and drug sensitivity.
Point Mutation
Introducing point mutations in the catalytic domain (e.g., cysteine to alanine in HECT ligases) via CRISPR can specifically inactivate ligase activity without affecting protein stability or interactions. This helps distinguish catalytic activity from scaffolding functions.
Knock-in
Knock-in of epitope tags (e.g., HA, FLAG) or fluorescent proteins at the endogenous locus enables tracking of ligase expression, localization, and interaction partners under physiological conditions. Knock-in of disease-associated mutations can model human pathologies.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of an E3 ligase can amplify its activity, useful for studying gain-of-function effects, identifying downstream targets, and screening for inhibitors. Overexpression models are particularly relevant for oncogenes like MDM2.
How EDITGENE Supports ubiquitin protein ligase activity Research
Researchers studying ubiquitin protein ligase activity-related genes often need to determine whether a candidate gene is causally involved in a specific cellular process or disease. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models, enabling functional validation of E3 ligases and their substrates.
Contact EDITGENE today to design your custom CRISPR model for ubiquitin protein ligase activity research.
Frequently Asked Questions About ubiquitin protein ligase activity
What is ubiquitin protein ligase activity?
Ubiquitin protein ligase activity (GO:0061630) is the catalytic transfer of ubiquitin to a substrate protein, forming an isopeptide bond between the C-terminal glycine of ubiquitin and a lysine residue in the substrate.
What genes are involved in ubiquitin protein ligase activity?
Genes encoding E3 ligases such as NEDD4, XIAP, Nedd4-2, Parkin, MDM2, and many others exhibit this activity.
What is the difference between E3 ligase and ubiquitin protein ligase activity?
E3 ligase is the enzyme that carries out ubiquitin protein ligase activity; the activity is the function, while E3 ligase is the protein.
How is ubiquitin protein ligase activity regulated?
It is regulated by post-translational modifications, autoinhibition, adaptor proteins, and substrate availability.
What diseases are associated with ubiquitin protein ligase activity?
Cancer, neurodegenerative diseases, and immune disorders are linked to dysregulated E3 ligase activity.
What methods are used to study ubiquitin protein ligase activity?
Activity-based probes, in vitro ubiquitination assays, CRISPR screens, and proteomics are common methods.
Can CRISPR be used to study ubiquitin protein ligase activity?
Yes, CRISPR knockout, knock-in, and overexpression models enable functional dissection of E3 ligases.
What is the role of NEDD4 in ubiquitin protein ligase activity?
NEDD4 is a HECT-type E3 ligase that regulates ion channels, receptors, and signaling proteins, and is implicated in cancer and neurological disorders.
How does XIAP ubiquitin ligase activity affect apoptosis?
XIAP promotes proteasomal degradation of caspase-3, enhancing its anti-apoptotic effect in Fas-induced cell death.
What is the clinical relevance of ubiquitin protein ligase activity?
E3 ligases are promising drug targets for cancer, neurodegeneration, and immune diseases, with several inhibitors in clinical trials.
Conclusion
Ubiquitin protein ligase activity (GO:0061630) is a central molecular function that governs protein fate and cellular signaling. Its dysregulation underlies numerous human diseases, making it a prime target for therapeutic intervention. Advances in CRISPR-based models and chemical probes continue to illuminate the mechanisms and regulation of E3 ligases, offering new opportunities for drug discovery. EDITGENE's comprehensive services support researchers in dissecting this critical activity with precision and scale.
References
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- 3. Robinson PA et al.. 2004. Ubiquitin-protein ligases--novel therapeutic targets?. Curr Protein Pept Sci 5(3):163-76 PMID: 15180521
- 4. Nair RM et al.. 2021. Reconstitution and Structural Analysis of a HECT Ligase-Ubiquitin Complex via an Activity-Based Probe.. ACS Chem Biol 16(9):1615-1621 PMID: 34403242
- 5. Suzuki Y et al.. 2001. Ubiquitin-protein ligase activity of X-linked inhibitor of apoptosis protein promotes proteasomal degradation of caspase-3 and enhances its anti-apoptotic effect in Fas-induced cell death.. Proc Natl Acad Sci U S A 98(15):8662-7 PMID: 11447297
- 6. Furniss JJ et al.. 2018. Proteasome-associated HECT-type ubiquitin ligase activity is required for plant immunity.. PLoS Pathog 14(11):e1007447 PMID: 30458055
- 7. Lee PL et al.. 1986. Multiple forms of ubiquitin-protein ligase. Binding of activated ubiquitin to protein substrates.. Biochemistry 25(11):3134-8 PMID: 3015198
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