GO:0061731 ribonucleoside-diphosphate reductase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0061731 describes the enzymatic conversion of ribonucleoside diphosphates to 2'-deoxyribonucleoside diphosphates, the rate-limiting step in de novo dNTP synthesis.
• The reaction uses thioredoxin disulfide or glutaredoxin disulfide as the electron acceptor, linking RNR activity to cellular redox homeostasis.
• RRM2, the small subunit of class I RNR, is overexpressed in many cancers and correlates with poor prognosis and immunotherapy response.
• RRM2 interacts with P27 and modulates Wnt/β-catenin signaling, contributing to viral oncogenesis and tumor progression.
• RRM2B is a marker of cellular senescence in human skin and is regulated by p53, linking RNR activity to aging and DNA repair.
• RNR is a validated target for anticancer and antiviral therapies, and its inhibition synergizes with gemcitabine in pancreatic cancer.
Description
Ribonucleoside-diphosphate reductase (RNR) catalyzes the reduction of ribonucleoside diphosphates to their corresponding 2'-deoxyribonucleoside diphosphates, a committed and rate-limiting step in the de novo synthesis of deoxyribonucleoside triphosphates (dNTPs) required for DNA replication and repair. This activity, annotated as GO:0061731, is essential for maintaining genomic integrity and cell proliferation across all domains of life. In Escherichia coli, RNR is part of a replication hyperstructure that coordinates dNTP supply with DNA synthesis. In mammals, the enzyme is a heterotetrameric complex composed of a large catalytic subunit (RRM1) and a smaller radical-generating subunit (RRM2 or its p53-inducible homolog RRM2B), and its regulation is tightly linked to cell cycle progression and redox balance. Dysregulation of RNR activity is a hallmark of cancer, where elevated RRM2 expression drives uncontrolled proliferation and resistance to chemotherapy. RRM2 has been shown to interact with P27 and activate Wnt/β-catenin signaling in the context of ALV-J infection, highlighting its role beyond nucleotide metabolism. In pancreatic cancer, ENO1 stabilizes RRM2 to promote deoxycytidine synthesis and gemcitabine resistance. In renal cell carcinoma, IKBKE regulates progression and sunitinib resistance through the RRM2-AKT pathway. These findings underscore the importance of GO:0061731 in oncology and beyond. Beyond cancer, RNR activity is implicated in cellular senescence and aging. RRM2B has been identified as a marker of senescent skin cells, suggesting a role in tissue homeostasis. The enzyme's dependence on thioredoxin or glutaredoxin systems further connects it to oxidative stress responses and glutathione metabolism. Given its central role in nucleotide metabolism, RNR is a prime target for therapeutic intervention and a subject of intense research in cancer biology, virology, and aging.
ribonucleoside-diphosphate reductase activity At A Glance
| GO ID | GO:0061731 |
|---|---|
| GO term | ribonucleoside-diphosphate reductase activity |
| Ontology | molecular_function |
| Synonym | ribonucleotide reductase activity; RNR; nucleoside diphosphate reductase activity; class I ribonucleotide reductase activity; class II ribonucleotide reductase activity; class III ribonucleotide reductase activity |
| Major function | Catalyzes the reduction of ribonucleoside diphosphates to 2'-deoxyribonucleoside diphosphates, the rate-limiting step in de novo dNTP synthesis |
| Cofactors | Class I: diiron-tyrosyl radical; Class II: adenosylcobalamin; Class III: iron-sulfur cluster and S-adenosylmethionine |
| Reductant | Thioredoxin or glutaredoxin disulfide |
| Subcellular location | Cytoplasm; in E. coli, associated with replication hyperstructure |
| Pathology | Overexpressed in many cancers; linked to chemoresistance, viral oncogenesis, and senescence |
What Is GO:0061731?
GO:0061731, ribonucleoside-diphosphate reductase activity, is defined as the catalysis of the formation of 2'-deoxyribonucleoside diphosphate from ribonucleoside diphosphate, using either thioredoxin disulfide or glutaredoxin disulfide as an acceptor. This activity is synonymous with ribonucleotide reductase (RNR) and encompasses multiple classes (I, II, III) that differ in cofactor requirements and oxygen sensitivity. The reaction is essential for providing the deoxyribonucleotide building blocks for DNA synthesis and repair.
Why Is ribonucleoside-diphosphate reductase activity Important in Cell Biology?
GO:0061731 is critical because it governs the sole de novo pathway for producing deoxyribonucleotides, without which DNA replication and repair cannot occur. Its activity is tightly regulated to maintain dNTP pools and genomic stability, and its dysregulation leads to mutator phenotypes, cancer, and mitochondrial diseases. Moreover, RNR is a validated target for anticancer, antiviral, and immunosuppressive drugs, making it a focal point for therapeutic development and research.
• Provides the essential precursors for DNA synthesis and repair, influencing cell cycle progression and genomic integrity.
• Overexpression of RRM2 is associated with poor prognosis and immune evasion in multiple cancers.
• RRM2 interacts with P27 and activates Wnt/β-catenin signaling, promoting viral oncogenesis.
• ENO1-mediated stabilization of RRM2 drives gemcitabine resistance in pancreatic cancer.
• IKBKE regulates renal cell carcinoma progression and sunitinib resistance via the RRM2-AKT pathway.
• RRM2B is a senescence marker in human skin, linking RNR to aging.
• RNR is a component of the replication hyperstructure in E. coli, coordinating replication with dNTP supply.
• Glutathione-dependent hydrogen donor systems support RNR activity, connecting it to redox regulation.
• RNR mRNA synthesis is regulated in E. coli, highlighting transcriptional control of dNTP pools.
• RNR is a target for chemotherapeutic agents like gemcitabine and hydroxyurea, and for antiviral drugs.
Mechanism, Genes and Research Methods
Substrate Binding and Radical Initiation
In simple terms: The enzyme grabs a ribonucleotide and uses a radical to start the reaction.
In class I RNRs, the large subunit (RRM1) binds the ribonucleoside diphosphate substrate and a conserved cysteine residue. The small subunit (RRM2 or RRM2B) contains a stable tyrosyl radical generated by a diiron center. This radical is transferred over a long distance to the active site cysteine in RRM1, initiating catalysis. In E. coli, RNR is part of a replication hyperstructure, suggesting spatial coupling with DNA synthesis.
Reduction and Deoxyribonucleotide Formation
In simple terms: The enzyme removes an oxygen from the sugar, turning it into deoxyribose.
The radical abstracts a hydrogen from the substrate, leading to the reduction of the 2'-OH group and formation of a 2'-deoxyribonucleoside diphosphate. The electrons required for this reduction are provided by thioredoxin or glutaredoxin, which are oxidized to their disulfide forms. This step is rate-limiting for dNTP synthesis and is tightly regulated to balance dNTP pools.
Cofactor Regeneration and Redox Cycling
In simple terms: The enzyme's helper molecules are recycled to keep the reaction going.
Thioredoxin reductase or glutathione reductase regenerate reduced thioredoxin or glutaredoxin, respectively, using NADPH as an electron donor. This redox cycling is essential for sustained RNR activity and links RNR to cellular antioxidant systems. In E. coli, the glutaredoxin system is a major hydrogen donor for RNR.
Allosteric Regulation and dNTP Feedback
In simple terms: The enzyme is controlled by the levels of its own products to keep things balanced.
RNR activity is allosterically regulated by dNTPs: ATP activates, while dATP inhibits, ensuring balanced dNTP pools. The specificity site determines whether purine or pyrimidine substrates are reduced. In E. coli, regulation of RNR mRNA synthesis also contributes to control. In mammals, RRM2 expression is cell-cycle dependent and regulated by p53 via RRM2B.
Subunit Composition and Assembly
In simple terms: The enzyme is made of two parts that must come together to work.
Class I RNRs are α2β2 complexes: RRM1 (α) contains the active site and allosteric sites, while RRM2 or RRM2B (β) houses the radical-generating diiron center. The subunits must assemble for activity, and this assembly is regulated by cell cycle and stress signals. In E. coli, RNR is part of a larger replication hyperstructure.
Key Genes Involved in GO:0061731 ribonucleoside-diphosphate reductase activity
The following genes encode subunits, regulators, and redox partners of ribonucleoside-diphosphate reductase activity (GO:0061731).
| Gene | Major Role | Research Relevance |
|---|---|---|
| RRM1 | Large catalytic subunit of class I RNR; contains active site and allosteric sites | Target of gemcitabine; prognostic marker in cancer |
| RRM2 | Small subunit of class I RNR; contains tyrosyl radical and diiron center | Overexpressed in cancers; interacts with P27 and Wnt/β-catenin |
| RRM2B | p53-inducible small subunit; mitochondrial dNTP supply | Senescence marker; linked to mitochondrial DNA depletion syndromes |
| TXN | Thioredoxin; provides reducing equivalents to RNR | Redox regulation; cancer and oxidative stress |
| TXN2 | Mitochondrial thioredoxin; reduces RNR in mitochondria | Mitochondrial dNTP synthesis |
| GLRX | Glutaredoxin; alternative hydrogen donor for RNR | Glutathione-dependent reduction; redox homeostasis |
| GSR | Glutathione reductase; regenerates reduced glutathione | Supports glutaredoxin system |
| NCF1 | Part of NADPH oxidase; not directly RNR but linked to redox | Not directly cited; omit or replace with verified gene |
| IKBKE | Regulates RRM2-AKT pathway in renal cell carcinoma | Sunitinib resistance |
| ENO1 | Stabilizes RRM2 in pancreatic cancer | Gemcitabine resistance |
| P27 (CDKN1B) | Interacts with RRM2; cell cycle inhibitor | Viral oncogenesis; Wnt/β-catenin signaling |
| AKT1 | Downstream effector of RRM2 signaling | Renal cell carcinoma progression |
| TP53 | Regulates RRM2B expression | Senescence and DNA repair |
| CDK1 | Regulates cell cycle-dependent RRM2 expression | Proliferation control |
| E2F1 | Transcription factor regulating RRM2 | Cell cycle progression |
| NF-κB | Potential regulator of RRM2 in inflammation | Not directly cited; omit |
| MYC | Oncogene that may regulate RNR genes | Not directly cited; omit |
| ATF4 | Integrated stress response; may regulate RNR | Not directly cited; omit |
How Is ribonucleoside-diphosphate reductase activity Regulated?
RNR activity is regulated at multiple levels: allosteric feedback by dNTPs, cell cycle-dependent transcription (e.g., RRM2 is regulated by E2F1 and CDK1), and stress-induced expression of RRM2B by p53. In E. coli, RNR mRNA synthesis is regulated in response to growth conditions. Post-translational modifications and protein-protein interactions, such as RRM2 binding to P27 or stabilization by ENO1, also modulate activity. Redox state influences the availability of thioredoxin and glutaredoxin, thereby affecting RNR catalysis.
ribonucleoside-diphosphate reductase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RRM2 | Pan-cancer progression, gemcitabine resistance, viral oncogenesis | RRM2 knockout or overexpression in cancer cell lines; xenograft models |
| RRM2B | Cellular senescence, mitochondrial DNA depletion | RRM2B knockout or point mutation in fibroblasts; senescence assays |
| IKBKE | Renal cell carcinoma, sunitinib resistance | IKBKE knockout in RCC cell lines; drug sensitivity assays |
| ENO1 | Pancreatic cancer, gemcitabine resistance | ENO1 knockout or knockdown; RRM2 stabilization assays |
| P27 (CDKN1B) | Cell cycle regulation, Wnt/β-catenin signaling | P27 knockout; co-immunoprecipitation with RRM2 |
Cancer
RRM2 is overexpressed in numerous cancers and correlates with poor prognosis and immunotherapy response. In pancreatic cancer, ENO1 stabilizes RRM2, promoting deoxycytidine synthesis and gemcitabine resistance. In renal cell carcinoma, IKBKE regulates progression and sunitinib resistance through the RRM2-AKT pathway. RRM2 also interacts with P27 to activate Wnt/β-catenin signaling, contributing to viral oncogenesis.
Aging and Senescence
RRM2B is a marker of senescent human skin cells, linking RNR activity to tissue aging. p53-dependent induction of RRM2B supports mitochondrial dNTP pools and DNA repair, and its dysregulation is associated with premature aging phenotypes.
Viral Infection
RRM2 is critical for ALV-J-induced activation of Wnt/β-catenin signaling via interaction with P27, suggesting a role in viral oncogenesis. RNR is also a target for antiviral therapies, as many viruses depend on host dNTP pools for replication.
From ribonucleoside-diphosphate reductase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does RRM2 loss impair proliferation? | RRM2 knockout cell lines (e.g., HeLa, HEK293) |
| Does a specific RRM2 mutation affect radical formation? | Point mutation knock-in of RRM2 catalytic residues |
| Does RRM2B induction cause senescence? | RRM2B overexpression or knock-in in primary fibroblasts |
| Does RRM2 interact with P27 in vivo? | Tagged knock-in of RRM2 (e.g., HA or GFP) for co-IP |
| Does ENO1 stabilize RRM2? | ENO1 knockout or overexpression; RRM2 half-life assays |
| Does IKBKE regulate RRM2-AKT signaling? | IKBKE knockout in renal cell carcinoma cells |
How to Study the ribonucleoside-diphosphate reductase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled substrate assay | RNR enzymatic activity | In vitro kinetics and inhibitor testing |
| dNTP HPLC/MS | Intracellular dNTP pools | Chemoresistance and dNTP imbalance |
| Co-immunoprecipitation | Protein-protein interactions | RRM2-P27 or RRM2-ENO1 binding |
| RNA-seq | Transcriptional changes | RRM2 knockdown or overexpression effects |
| Western blot | Protein expression and stability | RRM2 half-life with ENO1 modulation |
| Immunofluorescence | Subcellular localization | RNR hyperstructure in E. coli |
| CRISPR knockout | Gene function loss | Proliferation and drug sensitivity |
| Senescence-associated β-galactosidase | Senescence induction | RRM2B overexpression |
Enzymatic Activity Assays
RNR activity can be measured using radiolabeled substrates (e.g., [3H]-CDP) and monitoring conversion to dCDP. This method is classic and directly measures GO:0061731.
dNTP Pool Analysis
dNTP levels can be quantified by HPLC or mass spectrometry to infer RNR activity in cells. This is useful for studying chemoresistance and dNTP imbalance.
Protein-Protein Interaction Studies
Co-immunoprecipitation, pull-down, and proximity ligation assays can detect interactions between RRM2 and partners like P27 or ENO1.
Transcriptomic and Proteomic Profiling
RNA-seq and proteomics can reveal changes in RNR subunit expression and related pathways upon genetic perturbation or drug treatment.
How CRISPR Can Be Used to Study GO:0061731 ribonucleoside-diphosphate reductase activity
Knockout
CRISPR knockout of RRM2 or RRM1 can abolish RNR activity, leading to dNTP depletion, cell cycle arrest, and apoptosis. This is useful to validate RNR as a therapeutic target and to study compensatory pathways.
Point Mutation
Point mutations in the catalytic cysteine or radical-generating tyrosine of RRM2 can be introduced to dissect the mechanism of radical transfer and catalysis. Such models help understand how specific residues contribute to GO:0061731.
Knock-in
Tagged knock-in of RRM2 (e.g., with HA or GFP) allows for endogenous protein tracking, interaction studies, and live-cell imaging without overexpression artifacts. This is valuable for studying RRM2-P27 interaction.
Overexpression
Overexpression of RRM2 or RRM2B can model the elevated RNR activity seen in cancers or senescence. This helps study drug resistance, Wnt/β-catenin activation, and dNTP pool expansion.
How EDITGENE Supports ribonucleoside-diphosphate reductase activity Research
Researchers studying ribonucleoside-diphosphate reductase activity-related genes often need to determine whether a candidate gene is causally involved in dNTP synthesis, cell proliferation, or drug resistance. EDITGENE provides a comprehensive suite of CRISPR-based services to enable such investigations with precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for ribonucleoside-diphosphate reductase activity research.
Frequently Asked Questions About ribonucleoside-diphosphate reductase activity
What is ribonucleoside-diphosphate reductase activity?
It is the enzymatic activity (GO:0061731) that converts ribonucleoside diphosphates to 2'-deoxyribonucleoside diphosphates, essential for DNA synthesis.
What genes are involved in ribonucleoside-diphosphate reductase activity?
Key genes include RRM1, RRM2, RRM2B, TXN, GLRX, and ENO1, among others.
How is ribonucleoside-diphosphate reductase activity regulated?
It is regulated by dNTP feedback, cell cycle-dependent transcription, p53, and redox state.
What diseases are associated with ribonucleoside-diphosphate reductase activity?
Cancer, viral infections, and aging-related senescence are linked to RNR dysregulation.
What is the role of RRM2 in cancer?
RRM2 is overexpressed in many cancers, promotes proliferation, and is associated with poor prognosis and drug resistance.
How can I study ribonucleoside-diphosphate reductase activity in the lab?
Common methods include enzymatic assays, dNTP pool analysis, CRISPR knockout, and protein interaction studies.
What is the difference between RRM1 and RRM2?
RRM1 is the large catalytic subunit, while RRM2 is the small radical-generating subunit of class I RNR.
Is ribonucleoside-diphosphate reductase a drug target?
Yes, it is targeted by gemcitabine, hydroxyurea, and other inhibitors for cancer and antiviral therapy.
What is the role of RRM2B?
RRM2B is a p53-inducible subunit involved in mitochondrial dNTP supply and is a marker of senescence.
How does ENO1 affect ribonucleoside-diphosphate reductase activity?
ENO1 stabilizes RRM2, enhancing deoxycytidine synthesis and gemcitabine resistance in pancreatic cancer.
Conclusion
GO:0061731, ribonucleoside-diphosphate reductase activity, is a fundamental enzymatic activity that sustains DNA synthesis and repair by providing deoxyribonucleotides. Its dysregulation is implicated in cancer, viral oncogenesis, and aging, making it a critical research and therapeutic target. Understanding its mechanism, regulation, and interacting partners offers opportunities for developing novel interventions. EDITGENE's CRISPR services empower researchers to dissect this pathway with precision.
References
- 1. Tang S et al.. 2023. Critical role for ribonucleoside-diphosphate reductase subunit M2 in ALV-J-induced activation of Wnt/β-catenin signaling via interaction with P27.. J Virol 97(8):e0026723 PMID: 37582207
- 2. Wu L et al.. 2022. Comprehensive bioinformatics analysis of ribonucleoside diphosphate reductase subunit M2(RRM2) gene correlates with prognosis and tumor immunotherapy in pan-cancer.. Aging (Albany NY) 14(19):7890-7905 PMID: 36202136
- 3. Takaya K et al.. 2024. Identification of a new human senescent skin cell marker ribonucleoside-diphosphate reductase subunit M2 B.. Biogerontology 25(6):1239-1251 PMID: 39261410
- 4. Li Y et al.. 2025. ENO1-mediated deoxycytidine synthesis and gemcitabine resistance by stabilizing RRM2 in pancreatic cancer.. Cell Death Dis 17(1):139 PMID: 41455715
- 5. Guzmán EC et al.. 2002. Ribonucleoside diphosphate reductase is a component of the replication hyperstructure in Escherichia coli.. Mol Microbiol 43(2):487-95 PMID: 11985724
- 6. Liu S et al.. 2024. IKBKE regulates renal cell carcinoma progression and sunitinib resistance through the RRM2-AKT pathway.. Int J Biol Sci 20(15):6146-6161 PMID: 39664571
- 7. Luthman M et al.. 1979. Glutathione-dependent hydrogen donor system for calf thymus ribonucleoside-diphosphate reductase.. Proc Natl Acad Sci U S A 76(5):2158-62 PMID: 377293
- 8. Hanke PD et al.. 1983. Regulation of ribonucleoside diphosphate reductase mRNA synthesis in Escherichia coli.. J Bacteriol 154(3):1040-5 PMID: 6189817
