GO:0031372 UBC13-MMS2 complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0031372 describes the UBC13-MMS2 heterodimeric ubiquitin-conjugating enzyme complex that specifically assembles K63-linked polyubiquitin chains.
• The complex is conserved from yeast (Ubc13p-Mms2p) to humans (UBE2N-UBE2V1/UBE2V2) and plants (UBC35/UBC36-UEV1A/UEV1B/UEV1C/UEV1D).
• Its catalytic mechanism relies on a key residue insertion in Mms2 that positions the acceptor ubiquitin for K63-specific chain formation.
• The complex functions downstream of RING finger proteins such as hRNF8 and hRNF168 in DNA damage responses and PCNA polyubiquitination.
• Dysregulation of UBE2N/UBE2V1/UBE2V2 is linked to cancer, neurodegeneration, and impaired DNA repair.
• CRISPR knockout, point-mutation, knock-in, and overexpression models are essential to dissect the complex's roles in health and disease.
Description
The UBC13-MMS2 complex (GO:0031372) is a heterodimeric ubiquitin-conjugating enzyme (E2) complex that catalyzes the assembly of K63-linked polyubiquitin chains, a non-degradative ubiquitin linkage involved in DNA damage signaling, immune regulation, and protein trafficking. In Saccharomyces cerevisiae, the complex comprises Ubc13p and Mms2p; in humans, it comprises UBE2N (Ubc13) and UBE2V1 or UBE2V2 (Mms2 variants); and in plants, it comprises UBC35/UBC36 and UEV1A/UEV1B/UEV1C/UEV1D. This evolutionary conservation underscores its fundamental role in cellular physiology. Researchers study GO:0031372 to understand how K63-linked polyubiquitination is initiated and regulated, and how its dysfunction contributes to diseases such as cancer and neurodegeneration. The complex is a target for therapeutic intervention and a model system for dissecting E2-E3 interplay.
UBC13-MMS2 complex At A Glance
| GO ID | GO:0031372 |
|---|---|
| GO term | UBC13-MMS2 complex |
| Ontology | cellular_component |
| Synonym | BEN-UEV1A complex, ubc-13-uev-1 complex, UBE2N/UBE2NL complex, UBE2V1/UBE2V2 complex, Uev1A-ben complex |
| Major function | Catalyzes assembly of K63-linked polyubiquitin chains |
| Subunits (human) | UBE2N (catalytic) and UBE2V1 or UBE2V2 (variant) |
| Subunits (yeast) | Ubc13p and Mms2p |
| Subunits (plant) | UBC35/UBC36 and UEV1A/UEV1B/UEV1C/UEV1D |
| Cellular role | DNA damage response, PCNA polyubiquitination, NF-kB signaling |
What Is GO:0031372?
GO:0031372 is defined as a heterodimeric ubiquitin conjugating enzyme complex that catalyzes assembly of K63-linked polyubiquitin chains. In Saccharomyces cerevisiae, the complex comprises Ubc13p and Mms2p; in human it comprises UBE2N and UBE2V1/UBE2V2; and in plants UBC35/UBC36 and UEV1A/UEV1B/UEV1C/UEV1D-4. This complex is a cellular component that functions as a catalytic machine for non-degradative ubiquitination.
Why Is UBC13-MMS2 complex Important in Cell Biology?
The UBC13-MMS2 complex is essential for K63-linked polyubiquitination, a post-translational modification that regulates DNA repair, immune signaling, and protein trafficking without targeting substrates for degradation. Its dysfunction is implicated in cancer, neurodegeneration, and developmental disorders, making it a high-priority target for basic and translational research.
• Catalyzes K63-linked polyubiquitin chains, a non-degradative signal.
• Central to DNA damage response and PCNA polyubiquitination.
• Regulates NF-kB signaling and innate immunity.
• Implicated in cancer progression and chemoresistance.
• Linked to neurodegeneration and protein aggregation diseases.
• Conserved from yeast to plants to humans, enabling model organism studies.
• Target for small-molecule inhibitors and CRISPR-based screens.
• Provides a paradigm for E2-E3 RING finger interactions.
Structure and Composition of UBC13-MMS2 complex
Heterodimeric Core: UBE2N and UBE2V1/UBE2V2
In simple terms: The complex is made of two proteins: one that does the chemistry (UBE2N) and one that helps position the target (UBE2V1 or UBE2V2).
The human UBC13-MMS2 complex consists of the catalytic E2 enzyme UBE2N (Ubc13) and a catalytically inactive E2 variant, UBE2V1 or UBE2V2 (Mms2). The heterodimer is required for K63-linked chain formation; UBE2N alone cannot synthesize K63 chains efficiently.
Interface Specificity and Key Residue Insertion
In simple terms: A single amino acid in Mms2 acts like a key that fits into a pocket in Ubc13, ensuring the two proteins bind correctly.
A single Mms2 'key' residue insertion into a Ubc13 pocket determines the interface specificity of the human Lys63 ubiquitin conjugation complex. This structural feature is conserved and critical for complex assembly and function.
Ubiquitin Binding and Catalytic Site
In simple terms: The complex binds ubiquitin in a way that lines up the K63 residue for chain building.
NMR-based models of the ubiquitin-bound human Mms2-Ubc13 complex reveal the structural basis for lysine 63 chain catalysis, showing how the acceptor ubiquitin is positioned. Main chain and side chain dynamics of Mms2 in free and ubiquitin-bound states further elucidate the conformational changes required for catalysis.
Interaction with RING Finger E3 Ligases
In simple terms: The complex partners with RING finger proteins that bring in the substrate and activate ubiquitin transfer.
The UBC13-MMS2 complex interacts with RING finger proteins such as hRNF8 and hRNF168, which are critical for DNA damage signaling. Protein-protein interactions within an E2-RING finger complex have implications for ubiquitin-dependent DNA damage repair.
Conservation Across Species
In simple terms: The same complex exists in yeast, humans, and plants, with similar parts and jobs.
In Saccharomyces cerevisiae, the complex comprises Ubc13p and Mms2p; in plants, UBC35/UBC36 and UEV1A/UEV1B/UEV1C/UEV1D-4. This conservation allows researchers to use model organisms to study human disease mechanisms.
Key Genes Involved in GO:0031372 UBC13-MMS2 complex
The following genes and proteins are core components or regulators of the UBC13-MMS2 complex (GO:0031372).
| Gene | Major Role | Research Relevance |
|---|---|---|
| UBE2N | Catalytic E2 enzyme in the complex | Knockout reduces K63-linked polyubiquitination; target for cancer therapy |
| UBE2V1 | E2 variant, regulatory subunit | Modulates complex activity and substrate specificity |
| UBE2V2 | E2 variant, alternative to UBE2V1 | Redundant role in PCNA polyubiquitination |
| UBC13 (yeast) | Yeast ortholog of UBE2N | Model for DNA damage response |
| MMS2 (yeast) | Yeast ortholog of UBE2V1/2 | Model for K63 chain assembly |
| UBC35 (plant) | Plant ortholog of UBE2N | Plant development and stress responses |
| UBC36 (plant) | Plant ortholog of UBE2N | Plant development and stress responses |
| UEV1A (plant) | Plant E2 variant | Plant development and stress responses |
| UEV1B (plant) | Plant E2 variant | Plant development and stress responses |
| UEV1C (plant) | Plant E2 variant | Plant development and stress responses |
| UEV1D (plant) | Plant E2 variant | Plant development and stress responses |
| RNF8 | RING finger E3 ligase | Recruits UBC13-MMS2 to DNA damage sites |
| RNF168 | RING finger E3 ligase | Amplifies DNA damage signaling with UBC13-MMS2 |
| PCNA | Substrate for polyubiquitination | Readout of UBC13-MMS2 activity |
| hMMS2 | Human Mms2 variant | Redundant role in PCNA polyubiquitination |
How Is UBC13-MMS2 complex Regulated?
The UBC13-MMS2 complex is regulated at multiple levels. Its activity depends on interaction with RING finger E3 ligases such as hRNF8 and hRNF168, which recruit the complex to DNA damage sites and stimulate ubiquitin transfer. Post-translational modifications and subunit availability (e.g., UBE2V1 vs UBE2V2) further modulate its function. In yeast, the complex is regulated by the DNA damage checkpoint and ubiquitin-binding domains.
UBC13-MMS2 complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| UBE2N | Cancer, chemoresistance | Knockout and point-mutation cell lines |
| UBE2V1 | Cancer, immune disorders | Overexpression and knockout models |
| UBE2V2 | PCNA polyubiquitination defects | Knockout and knock-in models |
| RNF8 | DNA repair deficiency, cancer | Knockout and tagged knock-in |
| RNF168 | DNA repair deficiency, cancer | Knockout and tagged knock-in |
Cancer
Dysregulation of UBE2N and its variants is associated with cancer progression, chemoresistance, and poor prognosis. The complex promotes K63-linked polyubiquitination of PCNA and other substrates, facilitating DNA damage tolerance and survival of cancer cells.
Neurodegeneration
Impaired K63-linked polyubiquitination by the UBC13-MMS2 complex contributes to protein aggregation and neuronal death in neurodegenerative diseases.
Immune Disorders
The complex regulates NF-kB signaling downstream of RING finger proteins, and its dysfunction can lead to immunodeficiency or autoimmunity.
From UBC13-MMS2 complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does UBE2N loss reduce K63-linked polyubiquitination? | UBE2N knockout cell line |
| How does the Mms2 key residue affect complex assembly? | Point-mutation knock-in of Mms2 |
| Can UBE2V1 substitute for UBE2V2 in PCNA polyubiquitination? | Knock-in of UBE2V1 into UBE2V2 locus |
| Where is the complex localized after DNA damage? | Tagged knock-in of UBE2N with fluorescent tag |
| Does overexpression of UBE2N drive chemoresistance? | Overexpression cell model |
| What genes synthetically interact with UBE2N? | CRISPR library screening |
How to Study the UBC13-MMS2 complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NMR spectroscopy | Protein structure and dynamics | Complex assembly and ubiquitin binding |
| X-ray crystallography | Atomic structure | Interface and catalytic site |
| Mass spectrometry | Ubiquitin chain linkage and interactome | K63 chain identification |
| In vitro ubiquitination assay | Enzymatic activity | Complex function and inhibition |
| Fluorescence microscopy | Subcellular localization | DNA damage foci |
| CRISPR knockout screen | Gene essentiality and synthetic lethality | Pathway discovery |
| RNA-seq | Transcriptional changes | Downstream effects of complex loss |
| Proximity ligation assay | Protein-protein interactions | Complex formation in cells |
Proteomics and Ubiquitin Chain Analysis
Mass spectrometry-based proteomics can identify K63-linked ubiquitin chains and interacting proteins. Purification of the UBC13-MMS2 complex and in vitro ubiquitination assays are standard.
Structural Biology (NMR, Crystallography)
NMR and crystallography reveal the structural basis of complex assembly and catalysis, including the ubiquitin-bound state.
Cell-Based Imaging
Fluorescent tagging of UBE2N or UBE2V1 allows live-cell imaging of complex localization to DNA damage foci.
CRISPR Screens
Genome-wide CRISPR knockout screens can identify synthetic lethal partners and pathways dependent on UBC13-MMS2.
How CRISPR Can Be Used to Study GO:0031372 UBC13-MMS2 complex
Knockout
CRISPR knockout of UBE2N, UBE2V1, or UBE2V2 abolishes K63-linked polyubiquitination, leading to defective DNA damage responses and PCNA polyubiquitination. These models are used to study cancer cell vulnerabilities and synthetic lethality.
Point Mutation
Point mutations in the Mms2 key residue or UBE2N catalytic cysteine can be introduced to dissect interface specificity and catalytic mechanism.
Knock-in
Knock-in of tagged UBE2N or UBE2V1 allows tracking of complex localization and interactions in live cells. Knock-in of UBE2V1 into the UBE2V2 locus tests functional redundancy.
Overexpression
Overexpression of UBE2N or UBE2V1 can drive chemoresistance and enhance DNA damage tolerance, providing models for cancer progression.
How EDITGENE Supports UBC13-MMS2 complex Research
Researchers studying UBC13-MMS2 complex-related genes often need to determine whether a candidate gene is causally involved in K63-linked ubiquitination, DNA repair, or disease progression. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for such studies.
Contact EDITGENE today to design your custom CRISPR model for UBC13-MMS2 complex research.
Frequently Asked Questions About UBC13-MMS2 complex
What is the UBC13-MMS2 complex?
The UBC13-MMS2 complex (GO:0031372) is a heterodimeric ubiquitin-conjugating enzyme complex that catalyzes K63-linked polyubiquitin chains, involved in DNA repair and signaling.
What genes are involved in the UBC13-MMS2 complex?
Key genes include UBE2N, UBE2V1, UBE2V2 in humans; UBC13 and MMS2 in yeast; and UBC35/UBC36 and UEV1A/UEV1B/UEV1C/UEV1D in plants.
What is the function of UBE2N in the UBC13-MMS2 complex?
UBE2N is the catalytic E2 enzyme that, together with UBE2V1/UBE2V2, assembles K63-linked polyubiquitin chains.
How does the UBC13-MMS2 complex assemble K63-linked chains?
Mms2 positions the acceptor ubiquitin via a key residue insertion, allowing Ubc13 to catalyze K63-specific chain formation.
What diseases are associated with UBC13-MMS2 complex dysfunction?
Dysfunction is linked to cancer, neurodegeneration, and immune disorders due to defective DNA repair and signaling.
What is the role of RNF8 and RNF168 in UBC13-MMS2 function?
RNF8 and RNF168 are RING finger E3 ligases that recruit and activate the UBC13-MMS2 complex at DNA damage sites.
How can CRISPR be used to study the UBC13-MMS2 complex?
CRISPR knockout, point mutation, knock-in, and overexpression models allow dissection of complex function in DNA repair and disease.
What model organisms are used to study the UBC13-MMS2 complex?
Saccharomyces cerevisiae, human cell lines, and plants are common models due to conservation of the complex.
What is the difference between UBE2V1 and UBE2V2?
UBE2V1 and UBE2V2 are alternative E2 variants that can partner with UBE2N; they show functional redundancy in PCNA polyubiquitination.
How is the UBC13-MMS2 complex regulated?
It is regulated by interaction with RING finger E3 ligases, post-translational modifications, and subunit availability.
Conclusion
The UBC13-MMS2 complex (GO:0031372) is a conserved heterodimeric E2 enzyme complex essential for K63-linked polyubiquitination, with critical roles in DNA damage response, immune signaling, and disease. Understanding its structure, regulation, and function requires precise genetic models. EDITGENE's CRISPR services empower researchers to generate knockout, point-mutation, knock-in, and overexpression models to accelerate discoveries in this field.
References
- 1. Pastushok L et al.. 2005. A single Mms2 "key" residue insertion into a Ubc13 pocket determines the interface specificity of a human Lys63 ubiquitin conjugation complex.. J Biol Chem 280(18):17891-900 PMID: 15749714
- 2. McKenna S et al.. 2003. An NMR-based model of the ubiquitin-bound human ubiquitin conjugation complex Mms2.Ubc13. The structural basis for lysine 63 chain catalysis.. J Biol Chem 278(15):13151-8 PMID: 12569095
- 3. Campbell SJ et al.. 2012. Molecular insights into the function of RING finger (RNF)-containing proteins hRNF8 and hRNF168 in Ubc13/Mms2-dependent ubiquitylation.. J Biol Chem 287(28):23900-10 PMID: 22589545
- 4. Ptak C et al.. 2005. Purification and properties of the ubiquitin-conjugating enzymes Cdc34 and Ubc13.Mms2.. Methods Enzymol 398:43-54 PMID: 16275318
- 5. Ulrich HD. 2003. Protein-protein interactions within an E2-RING finger complex. Implications for ubiquitin-dependent DNA damage repair.. J Biol Chem 278(9):7051-8 PMID: 12496280
- 6. Spyracopoulos L et al.. 2005. Main chain and side chain dynamics of the ubiquitin conjugating enzyme variant human Mms2 in the free and ubiquitin-bound States.. Biochemistry 44(24):8770-81 PMID: 15952783
- 7. Brun J et al.. 2008. hMMS2 serves a redundant role in human PCNA polyubiquitination.. BMC Mol Biol 9:24 PMID: 18284681
- 8. Lee KY et al.. 2008. PCNA modifications for regulation of post-replication repair pathways.. Mol Cells 26(1):5-11 PMID: 18525240
