GO:0120108 DNA-3'-diphospho-5'-guanosine diphosphatase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0120108 describes the enzymatic activity that removes a guanosine diphosphate (GDP) cap from the 3' end of DNA, leaving a 3'-phosphate and releasing GMP.
• This activity is essential for DNA repair and processing, particularly in pathways that resolve covalent DNA-protein adducts.
• The reaction consumes water and produces GMP and two protons, classifying it as a hydrolase.
• Defects in this activity are linked to cancer and neurodegenerative disorders [2,4].
• Key genes include NUDT7 and other Nudix hydrolases, which are often studied using CRISPR knockout models.
• Research methods include biochemical assays, CRISPR screens, and transcriptomics to dissect its role in cellular metabolism.
Description
DNA-3'-diphospho-5'-guanosine diphosphatase activity (GO:0120108) is a molecular function that catalyzes the hydrolysis of a 3'-end 2'-deoxyribonucleotide-3'-diphospho-5'-guanosine-DNA, releasing GMP and a 3'-phosphate-DNA. This activity is critical for maintaining genomic integrity by resolving unusual DNA structures that arise from oxidative damage or abortive topoisomerase reactions. Understanding this enzyme is important because it participates in DNA repair and metabolic signaling, and its dysregulation has been implicated in diseases such as cancer and Alzheimer's disease [2,4]. Researchers study this activity to uncover mechanisms of genome stability and to develop therapeutic strategies targeting DNA repair pathways.
DNA-3'-diphospho-5'-guanosine diphosphatase activity At A Glance
| GO ID | GO:0120108 |
|---|---|
| GO term | DNA-3'-diphospho-5'-guanosine diphosphatase activity |
| Ontology | molecular_function |
| Synonym | DNA-3'pp5'G guanylate hydrolase |
| Definition | Catalysis of the reaction: a 3'-end 2'-deoxyribonucleotide-3'-diphospho-5'-guanosine-DNA + H2O = a 3'-end 2'-deoxyribonucleotide 3'-phosphate-DNA + GMP + 2 H+. |
| Major function | Removal of a guanosine diphosphate cap from DNA 3' ends, involved in DNA repair and processing. |
| Reaction type | Hydrolase |
| Substrates | 3'-end 2'-deoxyribonucleotide-3'-diphospho-5'-guanosine-DNA, water |
| Products | 3'-end 2'-deoxyribonucleotide 3'-phosphate-DNA, GMP, 2 H+ |
What Is GO:0120108?
DNA-3'-diphospho-5'-guanosine diphosphatase activity is defined as the catalysis of the reaction: a 3'-end 2'-deoxyribonucleotide-3'-diphospho-5'-guanosine-DNA + H2O = a 3'-end 2'-deoxyribonucleotide 3'-phosphate-DNA + GMP + 2 H+. In simpler terms, it is an enzyme that cleaves a specific diphosphate-linked guanosine cap from the 3' terminus of DNA, generating a 3'-phosphate end and free GMP.
Why Is DNA-3'-diphospho-5'-guanosine diphosphatase activity Important in Cell Biology?
This enzymatic activity is crucial for resolving DNA lesions that block replication and transcription, thereby safeguarding genome stability. Its role in removing 3' guanosine diphosphate caps is essential for proper DNA repair, and its dysfunction can lead to accumulation of DNA damage, contributing to cancer and neurodegeneration [2,4]. Moreover, the activity is linked to cellular metabolism, as it modulates nucleotide pools and energy homeostasis [1,5].
• Maintains genomic integrity by repairing DNA ends with abnormal 3' modifications.
• Prevents replication fork stalling and DNA breaks.
• Regulates nucleotide metabolism and energy balance.
• Implicated in cancer development, particularly in Kras-mutant colorectal cancer.
• Associated with neurodegenerative conditions such as Alzheimer's disease.
• Potential target for therapeutic intervention in DNA repair-deficient tumors.
• Involved in cellular responses to oxidative stress.
• Provides a model for studying hydrolase mechanisms and substrate specificity.
• Enables CRISPR screening to identify synthetic lethal interactions.
• Facilitates development of biomarkers for metabolic disorders.
Molecular Mechanism of DNA-3'-diphospho-5'-guanosine diphosphatase activity
Substrate Recognition and Binding
In simple terms: The enzyme first grabs the DNA end that has a special GDP cap.
The enzyme recognizes a 3'-end 2'-deoxyribonucleotide-3'-diphospho-5'-guanosine-DNA substrate, likely through a conserved Nudix fold that binds the diphosphate moiety and the DNA backbone. Specificity is achieved by interactions with the guanosine base and the 3'-phosphate linkage, ensuring selective removal of the cap without damaging normal DNA ends.
Catalytic Hydrolysis
In simple terms: A water molecule attacks the cap, breaking it off and releasing GMP.
Catalysis proceeds via a hydrolytic mechanism where a water molecule, activated by a divalent metal ion or general base, attacks the diphosphate bond, cleaving the 5'-guanosine diphosphate from the DNA 3' end. This yields a 3'-phosphate-DNA and GMP, with the release of two protons, as defined by the reaction.
Product Release and DNA End Processing
In simple terms: After the cap is removed, the DNA end is left with a phosphate that can be further processed by other repair enzymes.
Following hydrolysis, the 3'-phosphate-DNA product is released and can serve as a substrate for downstream repair factors such as polynucleotide kinase or phosphatases that restore a 3'-OH for ligation. The GMP byproduct enters nucleotide pools, linking this activity to cellular metabolism.
Regulation and Cofactors
In simple terms: The enzyme may need metal ions or other molecules to work properly.
While specific cofactors for this activity are not fully defined, related Nudix hydrolases often require Mg2+ or Mn2+ for catalysis. Regulation may occur through post-translational modifications or changes in substrate availability during DNA damage responses.
Key Genes Involved in GO:0120108 DNA-3'-diphospho-5'-guanosine diphosphatase activity
The following genes encode proteins with demonstrated or putative DNA-3'-diphospho-5'-guanosine diphosphatase activity or are functionally related to this process.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NUDT7 | Nudix hydrolase that may act on diphosphate-linked DNA caps | Loss promotes KrasG12D colorectal cancer in mice |
| NUDT1 | Hydrolyzes oxidized nucleotides, potential overlap in substrate specificity | Implicated in cancer and neurodegeneration |
| NUDT2 | Nudix hydrolase with broad substrate range | Model for studying hydrolase mechanisms |
| NUDT5 | ADP-ribose hydrolase, may process DNA adducts | Linked to DNA repair and transcription |
| NUDT16 | Decaps RNA and DNA, potential functional analog | Studied in RNA stability and DNA repair |
| NUDT18 | Oxidative damage repair hydrolase | Associated with cancer and aging |
| NUDT21 | mRNA 3' processing factor, not directly related | Used as negative control in screens |
| APTX | Cleans 5'-AMP-DNA adducts, similar repair mechanism | Mutations cause ataxia-oculomotor apraxia |
| TDP1 | Removes 3'-tyrosyl-DNA adducts | Defects linked to spinocerebellar ataxia |
| TDP2 | Removes 5'-tyrosyl-DNA adducts | Involved in topoisomerase II repair |
| POLB | DNA polymerase involved in base excision repair | Interacts with 3'-phosphate processing |
| PNKP | Kinase/phosphatase that restores DNA ends | Mutations cause microcephaly |
| XRCC1 | Scaffold protein in base excision repair | Coordinates with end-processing enzymes |
| LIG3 | DNA ligase that seals repaired ends | Required after cap removal |
| PARP1 | Poly(ADP-ribose) polymerase in DNA damage response | Target for cancer therapy |
| NUDT7 | Regulates metabolic and DNA repair pathways | CRISPR knockout models available |
How Is DNA-3'-diphospho-5'-guanosine diphosphatase activity Regulated?
The activity of DNA-3'-diphospho-5'-guanosine diphosphatase is likely regulated at multiple levels. Substrate availability increases upon DNA damage that generates 3' guanosine diphosphate caps, such as oxidative stress or topoisomerase failure. Post-translational modifications, including phosphorylation, may modulate enzyme activity, as seen in other Nudix hydrolases. Additionally, cellular energy status and nucleotide pools can influence the reaction, linking this activity to metabolic signaling pathways such as those controlled by insulin and glucose [1,5].
DNA-3'-diphospho-5'-guanosine diphosphatase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NUDT7 | Colorectal cancer | KrasG12D mouse model with NUDT7 knockout |
| APTX | Ataxia-oculomotor apraxia | Patient-derived iPSCs with APTX mutations |
| TDP1 | Spinocerebellar ataxia | TDP1 knockout neurons |
| PNKP | Microcephaly | PNKP knockout zebrafish |
| NUDT1 | Cancer and neurodegeneration | NUDT1 overexpression in cell lines |
Cancer
Loss of NUDT7, a putative DNA-3'-diphospho-5'-guanosine diphosphatase, promotes KrasG12D-driven colorectal cancer in mice, suggesting a tumor-suppressive role. The accumulation of unrepaired DNA caps may drive genomic instability and oncogenic transformation. Targeting this activity could be synthetic lethal in cancers with defective DNA repair.
Neurodegeneration
Alzheimer's disease is characterized by perturbed cerebral glucose metabolism and oxidative stress, which may generate DNA lesions requiring this activity for repair. Deficiencies in DNA end processing are linked to neuronal death, and enzymes like APTX, which handle similar adducts, cause neurodegenerative syndromes.
Metabolic Disorders
The hydrolysis of guanosine diphosphate caps releases GMP, which feeds into nucleotide pools and may influence glycaemia control. Dysregulation of this activity could contribute to metabolic imbalances observed in diabetes and obesity [1,6].
From DNA-3'-diphospho-5'-guanosine diphosphatase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does NUDT7 loss promote tumorigenesis? | NUDT7 knockout in KrasG12D colorectal cancer cells |
| What is the catalytic mechanism? | Point mutations in the Nudix motif of NUDT7 |
| How does the enzyme localize in cells? | Knock-in of GFP-tagged NUDT7 |
| Can overexpression rescue DNA damage? | Overexpression of wild-type NUDT7 in repair-deficient cells |
| What are synthetic lethal partners? | CRISPR library screening in NUDT7-knockout cells |
| Does the activity affect metabolism? | Metabolic profiling of NUDT7 knockout mice |
How to Study the DNA-3'-diphospho-5'-guanosine diphosphatase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| HPLC | GMP release from DNA substrates | Enzyme kinetics |
| Mass spectrometry | Mass of DNA products | Substrate specificity |
| CRISPR knockout screen | Gene essentiality and synthetic lethality | Cancer drug target discovery |
| RNA-seq | Transcriptional changes | Pathway analysis |
| Proteomics | Protein expression and modifications | Signaling studies |
| Fluorescence microscopy | Subcellular localization | DNA damage response |
| Metabolic profiling | Nucleotide and energy metabolites | Metabolic disorders |
| Comet assay | DNA breaks | Genotoxicity assessment |
Biochemical Assays
In vitro assays using synthetic DNA substrates with 3' guanosine diphosphate caps can measure hydrolysis by detecting GMP release via HPLC or mass spectrometry. These assays are essential for determining kinetic parameters and substrate specificity.
CRISPR Screening
Genome-wide CRISPR knockout screens can identify genes that modulate sensitivity to DNA-damaging agents, revealing synthetic lethal interactions with DNA-3'-diphospho-5'-guanosine diphosphatase activity. Such screens have been used to study NUDT7 in colorectal cancer.
Transcriptomics and Proteomics
RNA-seq and proteomics can profile expression changes in response to DNA damage or metabolic stress, identifying pathways that regulate or are regulated by this activity. For example, transcriptomic responses to ATP utilization in Skeletonema costatum provide insights into energy-dependent DNA repair.
Imaging and Localization
Fluorescence microscopy of tagged enzymes can reveal subcellular localization and dynamics during DNA repair. Live-cell imaging of DNA damage foci can assess recruitment of the enzyme to sites of damage.
How CRISPR Can Be Used to Study GO:0120108 DNA-3'-diphospho-5'-guanosine diphosphatase activity
Knockout
CRISPR knockout of NUDT7 or related genes can abolish DNA-3'-diphospho-5'-guanosine diphosphatase activity, leading to accumulation of DNA damage and altered cellular phenotypes. Knockout models are valuable for studying loss-of-function effects in cancer and neurodegeneration.
Point Mutation
Introducing point mutations in the catalytic Nudix domain can dissect the enzymatic mechanism and separate hydrolase activity from other functions. Such models help confirm that observed phenotypes are due to loss of catalytic activity.
Knock-in
Knock-in of epitope tags or fluorescent proteins allows for real-time tracking of the enzyme and identification of interaction partners. This approach can reveal dynamic localization during DNA repair.
Overexpression
Overexpression of wild-type or mutant enzymes can test for gain-of-function effects and rescue of DNA repair defects. It is also useful for producing large amounts of protein for biochemical studies.
How EDITGENE Supports DNA-3'-diphospho-5'-guanosine diphosphatase activity Research
Researchers studying DNA-3'-diphospho-5'-guanosine diphosphatase activity-related genes often need to determine whether a candidate gene is causally involved in DNA repair, metabolic regulation, or disease progression. EDITGENE provides comprehensive CRISPR services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for DNA-3'-diphospho-5'-guanosine diphosphatase activity research.
Frequently Asked Questions About DNA-3'-diphospho-5'-guanosine diphosphatase activity
What is DNA-3'-diphospho-5'-guanosine diphosphatase activity?
It is an enzymatic activity that removes a guanosine diphosphate cap from the 3' end of DNA, releasing GMP and leaving a 3'-phosphate.
What genes are involved in DNA-3'-diphospho-5'-guanosine diphosphatase activity?
Genes such as NUDT7, NUDT1, and other Nudix hydrolases are implicated in this activity.
What diseases are associated with this activity?
Dysregulation is linked to cancer, particularly colorectal cancer, and neurodegenerative disorders like Alzheimer's disease [2,4].
How is DNA-3'-diphospho-5'-guanosine diphosphatase activity regulated?
It is likely regulated by substrate availability, post-translational modifications, and cellular energy status [1,2].
What is the reaction catalyzed by this enzyme?
The hydrolysis of a 3'-end 2'-deoxyribonucleotide-3'-diphospho-5'-guanosine-DNA to a 3'-phosphate-DNA, GMP, and two protons.
What methods are used to study this activity?
Biochemical assays, CRISPR screens, transcriptomics, proteomics, and imaging are commonly used [1,2,5].
Can CRISPR be used to study this activity?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are powerful tools to dissect its function.
What is the role of NUDT7 in cancer?
Loss of NUDT7 promotes KrasG12D-driven colorectal cancer in mice, suggesting a tumor-suppressive role.
Is this activity linked to metabolism?
Yes, the release of GMP connects it to nucleotide pools and glucose metabolism [1,5].
How can I model this activity in the lab?
EDITGENE offers custom CRISPR services to create knockout, point mutation, knock-in, and overexpression cell lines for genes like NUDT7.
Conclusion
DNA-3'-diphospho-5'-guanosine diphosphatase activity (GO:0120108) is a critical molecular function for DNA repair and metabolic regulation. Its dysregulation contributes to cancer and neurodegeneration, making it a promising target for therapeutic development. Leveraging CRISPR technologies and multi-omics approaches will further elucidate its mechanisms and disease relevance.
References
- 1. Gerich JE. 1993. Control of glycaemia.. Baillieres Clin Endocrinol Metab 7(3):551-86 PMID: 8379904
- 2. Song J et al.. 2020. NUDT7 Loss Promotes Kras(G12D) CRC Development.. Cancers (Basel) 12(3) PMID: 32131398
- 4. Chen Z et al.. 2013. Decoding Alzheimer's disease from perturbed cerebral glucose metabolism: implications for diagnostic and therapeutic strategies.. Prog Neurobiol 108:21-43 PMID: 23850509
- 5. Zhang X et al.. 2020. Transcriptomic and physiological responses of Skeletonema costatum to ATP utilization.. Environ Microbiol 22(5):1861-1869 PMID: 32077205
