GO:0006189 'de novo' IMP biosynthetic process: Purine Biosynthesis Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0006189 describes the stepwise assembly of the purine ring on ribose 5-phosphate to form inosine monophosphate (IMP), the first fully formed purine nucleotide.
• The pathway consumes ATP and requires a coordinated set of enzymes including PPAT, GART, PFAS, PAICS, ADSL, and ATIC.
• Disorders of de novo purine biosynthesis cause a spectrum of neurological and systemic diseases, including AICA-ribosiduria, Lesch-Nyhan syndrome, and adenylosuccinate lyase deficiency.
• Cancer cells frequently upregulate de novo purine biosynthesis to sustain proliferation, and IMPDH2 is a validated target in glioblastoma.
• Nuclear IMPDH2 controls the DNA damage response by modulating PARP1 activity, linking purine biosynthesis to genome stability.
• CRISPR knockout, point mutation, knock-in, and overexpression models enable causal dissection of each enzymatic step in the pathway.
Description
The 'de novo' IMP biosynthetic process (GO:0006189) is the metabolic route by which cells build inosine monophosphate from simple precursors, rather than salvaging preformed purine bases. This pathway is essential for supplying the purine nucleotides required for DNA and RNA synthesis, energy metabolism, and signaling. Because rapidly dividing cells depend heavily on de novo purine synthesis, the pathway is a focal point in cancer biology, immunology, and neurodevelopment. At the molecular level, the pathway proceeds through a series of enzymatic reactions that assemble the purine ring atom by atom on ribose 5-phosphate, consuming ATP and other cofactors. The enzymes involved are organized in a multi-enzyme complex called the purinosome, which facilitates substrate channeling and pathway efficiency. Genetic defects in these enzymes cause severe metabolic and neurological disorders, underscoring the pathway's physiological importance. For researchers, GO:0006189 provides a structured framework to study metabolic reprogramming, drug resistance, and inherited metabolic disease. Recent work has also revealed non-canonical roles for pathway enzymes, such as IMPDH2 in the DNA damage response and nucleolar function, expanding the biological scope of this GO term.
'de novo' IMP biosynthetic process At A Glance
| GO ID | GO:0006189 |
|---|---|
| GO term | 'de novo' IMP biosynthetic process |
| Ontology | biological_process |
| Synonym | 'de novo' IMP anabolism; 'de novo' IMP biosynthesis; 'de novo' IMP formation; 'de novo' IMP synthesis; 'de novo' purine biosynthesis; 'de novo' purine biosynthetic process |
| Major function | Stepwise assembly of the purine ring on ribose 5-phosphate to form IMP, the first fully formed purine nucleotide |
| Key enzymes | PPAT, GART, PFAS, PAICS, ADSL, ATIC |
| Subcellular location | Cytosol; enzymes can assemble into purinosomes |
| Pathway end product | Inosine monophosphate (IMP), which is further converted to AMP and GMP |
What Is GO:0006189?
GO:0006189, 'de novo' IMP biosynthetic process, is defined as the chemical reactions and pathways resulting in the formation of IMP (inosine monophosphate) by the stepwise assembly of a purine ring on ribose 5-phosphate. In other words, it is the biosynthetic route that builds the purine nucleotide IMP from scratch, starting from 5-phosphoribosyl-1-pyrophosphate (PRPP) and simple molecules like glycine, glutamine, aspartate, and formate, rather than recycling preformed purine bases.
Why Is 'de novo' IMP biosynthetic process Important in Cell Biology?
The de novo IMP biosynthetic process is essential for cellular proliferation and survival because it provides the purine nucleotides needed for DNA replication, RNA transcription, and energy metabolism. Its dysregulation is implicated in cancer, where tumor cells often upregulate purine synthesis to meet biosynthetic demands. Inherited defects in pathway enzymes cause severe neurological and systemic disorders, making the pathway clinically relevant. Additionally, the pathway intersects with immune cell function, as classically activated macrophages undergo nucleotide metabolism remodeling driven by nitric oxide.
• Supplies purine nucleotides for DNA and RNA synthesis in proliferating cells.
• Upregulated in many cancers, including glioblastoma, where IMPDH2 drives tumorigenesis.
• Genetic defects cause disorders such as AICA-ribosiduria and adenylosuccinate lyase deficiency.
• Nuclear IMPDH2 modulates PARP1 activity and the DNA damage response.
• Purinosome assembly is regulated by metabolic cues and is a target of drugs like metformin.
• Macrophage activation remodels nucleotide metabolism, linking purine synthesis to inflammation.
• Provides metabolic intermediates for signaling and post-translational modifications.
• Serves as a model system for studying multi-enzyme complex assembly and substrate channeling.
• Relevant to antimetabolite drug development, including methotrexate and mycophenolate.
• Enables CRISPR-based dissection of metabolic gene function in disease models.
What Happens During 'de novo' IMP biosynthetic process?
Activation of ribose 5-phosphate to PRPP
In simple terms: The cell first activates a sugar phosphate so it can accept the building blocks of the purine ring.
The pathway begins with the conversion of ribose 5-phosphate to 5-phosphoribosyl-1-pyrophosphate (PRPP) by PRPS1/2, consuming ATP. PRPP is the activated sugar moiety on which the purine ring is assembled. This step links the pentose phosphate pathway to purine biosynthesis and is a key regulatory node.
Early steps: formation of formylglycinamide ribonucleotide
In simple terms: The first few reactions attach nitrogen and carbon atoms to the sugar, building the initial scaffold.
PPAT transfers the pyrophosphate group of PRPP to glutamine, releasing glutamate and forming 5-phosphoribosylamine (PRA). GART then catalyzes three sequential reactions: glycinamide ribonucleotide (GAR) synthesis, formylation to formylglycinamide ribonucleotide (FGAR), and amidation to formylglycinamidine ribonucleotide (FGAM). These steps consume ATP and glutamine and are essential for ring assembly.
Ring closure and imidazole formation
In simple terms: The growing molecule folds into a five-membered ring, creating the core of the purine structure.
PFAS (also known as FGAM synthetase) catalyzes the ATP-dependent conversion of FGAM to aminoimidazole ribonucleotide (AIR), closing the imidazole ring. This step is a critical checkpoint and is targeted by antifolate drugs that deplete tetrahydrofolate cofactors.
Carboxylation and succinylaminoimidazole carboxamide ribotide formation
In simple terms: The ring is decorated with additional atoms that will become part of the final purine.
PAICS is a bifunctional enzyme that first carboxylates AIR to carboxyaminoimidazole ribonucleotide (CAIR) and then converts CAIR to succinylaminoimidazole carboxamide ribotide (SAICAR) using aspartate and ATP. This step introduces the atoms that will form the six-membered ring of the purine.
Final steps: formation of IMP
In simple terms: The last reactions remove extra groups and close the second ring to produce the finished nucleotide.
ADSL cleaves SAICAR to aminoimidazole carboxamide ribotide (AICAR) and fumarate. ATIC then formylates AICAR to formylaminoimidazole carboxamide ribotide (FAICAR) and catalyzes the final cyclization to IMP. IMP is the first fully formed purine nucleotide and serves as the branch point for AMP and GMP synthesis.
Key Genes Involved in GO:0006189 'de novo' IMP biosynthetic process
The following genes encode enzymes and regulators that carry out or control the 'de novo' IMP biosynthetic process.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PRPS1 | Converts ribose 5-phosphate to PRPP | Mutations cause PRPS1 superactivity and Arts syndrome |
| PPAT | Catalyzes formation of 5-phosphoribosylamine | First committed step of purine biosynthesis |
| GART | Trifunctional enzyme in early purine synthesis | Target of antifolates; mutations cause neurological disease |
| PFAS | Closes imidazole ring to form AIR | Regulated by purinosome assembly |
| PAICS | Bifunctional enzyme producing SAICAR | Overexpressed in multiple cancers |
| ADSL | Cleaves SAICAR to AICAR and fumarate | Deficiency causes adenylosuccinate lyase deficiency |
| ATIC | Final two steps to IMP | Bifunctional enzyme; mutations cause AICA-ribosiduria |
| IMPDH1 | Converts IMP to XMP | Retinal degeneration in IMPDH1 mutations |
| IMPDH2 | Converts IMP to XMP; nuclear role in DNA damage response | Drives glioblastoma tumorigenesis |
| GMPS | Converts XMP to GMP | Links purine synthesis to GMP pools |
| ADSS1 | Converts IMP to adenylosuccinate | Muscle-specific isoform; relevant to myopathy |
| ADSS2 | Converts IMP to adenylosuccinate | Ubiquitous isoform |
| PPAT | Purinosome component | Forms complex with GART and PFAS |
| GART | Purinosome component | Assembles with PPAT and PFAS |
| PFAS | Purinosome component | Assembles with PPAT and GART |
| MYC | Transcriptionally activates purine synthesis genes | Drives metabolic reprogramming in cancer |
| BRD4 | Regulates MYC expression | Target of BET inhibitors affecting purine synthesis |
How Is 'de novo' IMP biosynthetic process Regulated?
The 'de novo' IMP biosynthetic process is regulated at multiple levels. Transcriptionally, the MYC oncogene activates expression of multiple purine synthesis genes, and BRD4 regulates MYC expression, linking chromatin signaling to metabolic flux. Post-translationally, the pathway enzymes can assemble into a multi-enzyme complex called the purinosome, which enhances substrate channeling and is dynamically regulated by metabolic demand. Metformin has been shown to modulate purinosome assembly and purine pathway flux in rats. Additionally, nitric oxide drives nucleotide metabolism remodeling in classically activated macrophages, altering purine synthesis. Nuclear IMPDH2 is regulated by PARP1 activity and influences the DNA damage response.
'de novo' IMP biosynthetic process and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ADSL | Adenylosuccinate lyase deficiency with psychomotor retardation | Knockout or point-mutation iPSC-derived neurons |
| ATIC | AICA-ribosiduria with severe neurological impairment | Knock-in mouse models of patient mutations |
| IMPDH2 | Glioblastoma tumorigenesis and DNA damage response | Knockout or overexpression in glioblastoma cell lines |
| PRPS1 | Arts syndrome and PRPS1 superactivity | Point-mutation knock-in in HEK293 or iPSCs |
| MYC | Metabolic reprogramming in cancer | CRISPR knockout or inducible overexpression in cancer cells |
Inherited disorders of purine biosynthesis
Biallelic mutations in enzymes of the de novo IMP biosynthetic process cause severe metabolic disorders. ADSL deficiency leads to accumulation of succinylpurines and presents with psychomotor retardation, epilepsy, and autistic features. ATIC mutations cause AICA-ribosiduria, characterized by severe neurological impairment and dysmorphic features. PRPS1 superactivity causes hyperuricemia and gout, while PRPS1 loss-of-function causes Arts syndrome with sensorineural deafness and intellectual disability.
Cancer metabolism and glioblastoma
Many cancers upregulate de novo purine biosynthesis to support rapid proliferation. In glioblastoma, IMPDH2 drives aberrant nucleolar activity and promotes tumorigenesis, and its inhibition reduces tumor growth. Nuclear IMPDH2 also controls the DNA damage response by modulating PARP1 activity, suggesting that targeting this enzyme may sensitize tumors to DNA-damaging agents. MYC-driven cancers depend on purine synthesis, and BET inhibitors that downregulate MYC reduce pathway flux.
Neurological and developmental disorders
Disorders of purine biosynthesis metabolism frequently present with neurological symptoms, including intellectual disability, seizures, and cerebellar hypoplasia. Mutations in MAST1, a gene not directly in the pathway but linked to purine-related metabolic stress, cause mega-corpus-callosum syndrome with cerebellar hypoplasia and cortical malformations. These findings highlight the importance of purine homeostasis for brain development.
Inflammation and macrophage function
Classically activated macrophages undergo functionally significant nucleotide metabolism remodeling driven by nitric oxide, which affects purine synthesis and downstream inflammatory responses. This links the de novo IMP biosynthetic process to immune regulation and suggests that targeting purine metabolism could modulate inflammation.
From 'de novo' IMP biosynthetic process-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of ADSL impair neuronal differentiation? | ADSL knockout iPSC-derived neurons |
| Does a patient-specific ATIC mutation alter IMP levels? | ATIC point-mutation knock-in HEK293 cells |
| Does IMPDH2 nuclear localization affect PARP1 activity? | IMPDH2 tagged knock-in with localization tag |
| Does MYC overexpression increase purine flux? | MYC overexpression in cancer cell lines |
| Does metformin alter purinosome assembly? | Purinosome reporter knock-in in hepatocytes |
| Does nitric oxide remodel macrophage purine metabolism? | Macrophage-specific knockout of pathway enzymes |
How to Study the 'de novo' IMP biosynthetic process Process
| Method | What It Measures | Typical Application |
|---|---|---|
| LC-MS metabolomics | Levels of IMP and intermediates | Quantify pathway activity in cells |
| Stable isotope tracing | Flux through de novo purine synthesis | Assess metabolic reprogramming |
| CRISPR knockout screens | Gene essentiality for pathway function | Identify novel regulators |
| SLAM-seq | Direct transcriptional changes | Measure MYC target gene expression |
| Fluorescence microscopy | Purinosome assembly and localization | Study enzyme complex dynamics |
| Co-immunoprecipitation | Protein-protein interactions | Validate purinosome components |
| Immunofluorescence | Nuclear IMPDH2 localization | Link to DNA damage response |
| Animal phenotyping | Neurological and metabolic traits | Model inherited disorders |
Metabolomics and flux analysis
Liquid chromatography-mass spectrometry (LC-MS) can quantify IMP and intermediate metabolites to assess pathway activity. Stable isotope tracing with 13C-glycine or 15N-glutamine enables flux analysis through the de novo pathway. These methods are essential for validating genetic models of purine biosynthesis.
CRISPR screening and functional genomics
Genome-wide CRISPR knockout screens can identify genes required for de novo IMP biosynthesis under specific growth conditions. SLAM-seq can measure direct transcriptional effects of pathway regulators like MYC. These approaches link genotype to metabolic phenotype.
Imaging and protein interaction studies
Fluorescence microscopy of tagged pathway enzymes reveals purinosome assembly and dynamics. Proximity ligation assays and co-immunoprecipitation can confirm interactions among PPAT, GART, and PFAS. Nuclear IMPDH2 localization can be visualized by immunofluorescence.
Animal models and disease phenotyping
Knockout and knock-in mouse models of pathway enzymes recapitulate neurological and metabolic phenotypes. Metformin-treated rats have been used to study purine pathway modulation and purinosome assembly. These models are critical for preclinical drug testing.
How CRISPR Can Be Used to Study GO:0006189 'de novo' IMP biosynthetic process
Knockout
CRISPR knockout of genes such as ADSL, ATIC, or IMPDH2 can abolish specific steps in the de novo IMP biosynthetic process, allowing researchers to assess metabolic dependencies and compensatory pathways. Knockout cell lines are valuable for drug sensitivity screens and for modeling inherited enzyme deficiencies.
Point Mutation
Point mutations identified in patients with purine biosynthesis disorders can be introduced into cell lines using CRISPR base editing or homology-directed repair. These models help distinguish loss-of-function from gain-of-function effects and reveal structure-function relationships in pathway enzymes.
Knock-in
Knock-in of epitope tags or fluorescent reporters into endogenous loci enables real-time tracking of enzyme localization and purinosome assembly. Tagged IMPDH2 knock-in cells have been used to study nuclear localization and PARP1 interaction.
Overexpression
CRISPR activation or lentiviral overexpression of MYC or IMPDH2 can drive pathway upregulation, mimicking cancer-associated metabolic reprogramming. Overexpression models are useful for testing inhibitors and for studying pathway flux under saturating conditions.
How EDITGENE Supports 'de novo' IMP biosynthetic process Research
Researchers studying 'de novo' IMP biosynthetic process-related genes often need to determine whether a candidate gene is causally involved in pathway regulation, disease progression, or drug response. Rigorous genetic models are essential to move from correlation to causation.
Contact EDITGENE today to design your custom CRISPR model for 'de novo' IMP biosynthetic process research.
Frequently Asked Questions About 'de novo' IMP biosynthetic process
What is the 'de novo' IMP biosynthetic process?
It is the metabolic pathway that builds inosine monophosphate (IMP) from simple precursors by stepwise assembly of a purine ring on ribose 5-phosphate, as defined by GO:0006189.
What genes are involved in 'de novo' IMP biosynthetic process?
Key genes include PRPS1, PPAT, GART, PFAS, PAICS, ADSL, and ATIC, which encode the enzymes that catalyze each step.
Why is de novo purine biosynthesis important in cancer?
Many cancer cells upregulate this pathway to support rapid proliferation, and enzymes like IMPDH2 are validated oncogenic targets.
What diseases are linked to defects in de novo IMP biosynthesis?
Inherited disorders include adenylosuccinate lyase deficiency, AICA-ribosiduria, and Arts syndrome, often presenting with neurological symptoms.
How is the 'de novo' IMP biosynthetic process regulated?
It is regulated transcriptionally by MYC and BRD4, and post-translationally by purinosome assembly and metabolic cues.
What is a purinosome?
A purinosome is a multi-enzyme complex of de novo purine biosynthesis enzymes that forms to enhance substrate channeling and pathway efficiency.
How can CRISPR be used to study de novo IMP biosynthesis?
CRISPR knockout, point mutation, knock-in, and overexpression models allow causal testing of each pathway gene in disease-relevant cells.
What methods measure de novo IMP biosynthesis flux?
LC-MS metabolomics and stable isotope tracing with 13C-glycine or 15N-glutamine are standard methods.
Is IMPDH2 involved in DNA damage response?
Yes, nuclear IMPDH2 modulates PARP1 activity and influences the DNA damage response.
What model systems are available for studying purine biosynthesis disorders?
iPSC-derived neurons, knockout mice, and patient-specific knock-in cell lines are commonly used.
Conclusion
The 'de novo' IMP biosynthetic process (GO:0006189) is a central metabolic pathway that supplies purine nucleotides for cell growth and function. Its dysregulation underlies cancer, inherited metabolic disorders, and immune dysfunction. Advances in CRISPR modeling and metabolomics now enable precise dissection of each enzymatic step and its regulatory network. Continued research into this pathway will inform new therapeutic strategies for metabolic and proliferative diseases.
References
- 2. John SV et al.. 2025. Classically activated macrophages undergo functionally significant nucleotide metabolism remodelling driven by nitric oxide.. Nat Metab 7(8):1681-1702 PMID: 40759751
- 3. Espinar L et al.. 2024. Nuclear IMPDH2 controls the DNA damage response by modulating PARP1 activity.. Nat Commun 15(1):9515 PMID: 39532854
- 4. Muhar M et al.. 2018. SLAM-seq defines direct gene-regulatory functions of the BRD4-MYC axis.. Science 360(6390):800-805 PMID: 29622725
- 5. Yu Q et al.. 2025. Mechanistic insights into metformin's anti-hyperuricemic effect: Targeting PPP/DNPB/XOD-mediated purine pathway, purinosome assembly, and gut microbiota homostasis in rats.. Chem Biol Interact 421:111783 PMID: 41109441
- 6. Dewulf JP et al.. 2022. Disorders of purine biosynthesis metabolism.. Mol Genet Metab 136(3):190-198 PMID: 34998670
- 7. Tripathy R et al.. 2018. Mutations in MAST1 Cause Mega-Corpus-Callosum Syndrome with Cerebellar Hypoplasia and Cortical Malformations.. Neuron 100(6):1354-1368.e5 PMID: 30449657
- 8. Kofuji S et al.. 2019. IMP dehydrogenase-2 drives aberrant nucleolar activity and promotes tumorigenesis in glioblastoma.. Nat Cell Biol 21(8):1003-1014 PMID: 31371825
