GO:0009168 purine ribonucleoside monophosphate biosynthetic process: Nucleotide Synthesis Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0009168 describes the de novo and salvage routes that build purine ribonucleoside monophosphates such as AMP, GMP, IMP, and XMP, which are essential for RNA, DNA, and cofactor synthesis.
• The pathway is a core target of antimetabolite drugs including 6-thioguanine, 6-mercaptopurine, and 8-azaguanine, which are converted into fraudulent ribonucleoside monophosphates that inhibit downstream enzymes.
• Purine ribonucleoside monophosphates can directly inhibit viral DNA polymerases, as shown for herpes simplex virus DNA polymerase.
• Adenosine kinase regulates intracellular adenosine and AMP levels, making it a therapeutic target in neurological and inflammatory conditions.
• Inhibitors of AMP deaminase and adenosine deaminase are designed based on the mechanism and structure of these purine-metabolizing enzymes.
• Network and co-expression analyses link purine ribonucleoside monophosphate biosynthetic genes to hypertrophic cardiomyopathy and membranous glomerulonephritis.
Description
Purine ribonucleoside monophosphate biosynthetic process (GO:0009168) is the set of chemical reactions and pathways that produce purine ribonucleoside monophosphates, compounds composed of a purine base linked to a ribose sugar esterified with phosphate on the sugar. These molecules, including AMP, GMP, IMP, and XMP, are the activated precursors for RNA and DNA synthesis and are central to cellular energy metabolism and signaling. The pathway encompasses both de novo synthesis from simple precursors and salvage routes that recycle purine bases and nucleosides. Because purine ribonucleoside monophosphates are required for nucleic acid synthesis and because their analogues can act as antimetabolites, this process is a major focus in cancer, antiviral, and immunology research. Experimental evidence shows that purine ribonucleoside monophosphates can directly inhibit herpes simplex virus DNA polymerase, demonstrating their potential as antiviral agents. In addition, adenosine kinase, a key enzyme in purine ribonucleoside monophosphate metabolism, is being exploited for therapeutic gain in neurological and inflammatory diseases. Understanding GO:0009168 is therefore essential for researchers studying nucleotide metabolism, drug resistance, and metabolic disorders.
purine ribonucleoside monophosphate biosynthetic process At A Glance
| GO ID | GO:0009168 |
|---|---|
| GO term | purine ribonucleoside monophosphate biosynthetic process |
| Ontology | biological_process |
| Synonym | purine ribonucleoside monophosphate anabolism; purine ribonucleoside monophosphate biosynthesis; purine ribonucleoside monophosphate formation; purine ribonucleoside monophosphate synthesis |
| Major function | Production of purine ribonucleoside monophosphates (AMP, GMP, IMP, XMP) for nucleic acid synthesis and cellular metabolism |
| Key enzymes | Adenosine kinase, AMP deaminase, adenosine deaminase, hypoxanthine-guanine phosphoribosyltransferase, and other purine salvage and de novo enzymes |
| Disease relevance | Cancer, viral infections, neurological disorders, hypertrophic cardiomyopathy, membranous glomerulonephritis |
| Therapeutic targeting | Antimetabolites such as 6-thioguanine, 6-mercaptopurine, and 8-azaguanine are converted to purine ribonucleoside monophosphate analogues that inhibit downstream enzymes |
What Is GO:0009168?
GO:0009168, purine ribonucleoside monophosphate biosynthetic process, is defined as the chemical reactions and pathways resulting in the formation of purine ribonucleoside monophosphate, a compound consisting of a purine base linked to a ribose sugar esterified with phosphate on the sugar. This process includes both de novo synthesis and salvage pathways that generate AMP, GMP, IMP, and related nucleotides, which serve as building blocks for RNA and DNA and as regulators of enzyme activity.
Why Is purine ribonucleoside monophosphate biosynthetic process Important in Cell Biology?
Purine ribonucleoside monophosphate biosynthetic process is fundamental to all living cells because it supplies the activated nucleotide precursors required for RNA and DNA synthesis, energy transfer, and signal transduction. Dysregulation of this pathway is associated with cancer, viral infections, and metabolic disorders, and the enzymes involved are validated targets for antimetabolite and antiviral drugs. For example, 6-thioguanine, 6-mercaptopurine, and 8-azaguanine require conversion to their respective ribonucleoside monophosphates to exert cytotoxicity, and resistance to these drugs often involves alterations in this pathway. Moreover, purine ribonucleoside monophosphates can directly inhibit viral DNA polymerases, providing a mechanism for antiviral activity. In neurological and inflammatory diseases, adenosine kinase, which regulates adenosine and AMP levels, is a promising therapeutic target. Thus, understanding GO:0009168 is critical for drug development, biomarker discovery, and mechanistic studies of metabolic diseases.
• Provides the essential building blocks for RNA and DNA synthesis, linking directly to cell proliferation and growth.
• Serves as the activation step for antimetabolite drugs such as 6-thioguanine, 6-mercaptopurine, and 8-azaguanine, which are used in cancer and autoimmune diseases.
• Generates purine ribonucleoside monophosphates that can inhibit viral DNA polymerases, offering a target for antiviral therapy.
• Adenosine kinase, a key enzyme in the pathway, is a therapeutic target for neurological and inflammatory conditions.
• Inhibitors of AMP deaminase and adenosine deaminase are designed based on the mechanism and structure of purine-metabolizing enzymes.
• Alterations in purine metabolism are linked to hypertrophic cardiomyopathy through gene co-expression network analysis.
• Metabolomic network analysis of membranous glomerulonephritis implicates purine ribonucleoside monophosphate pathways.
• The pathway is relevant to host-pathogen interactions, as shown by studies on adenosine analogue metabolism in Schistosoma mansoni.
• Understanding the pathway aids in predicting drug resistance mechanisms in cancer and infectious diseases.
• It is a model system for studying enzyme kinetics, allosteric regulation, and metabolic flux.
What Happens During purine ribonucleoside monophosphate biosynthetic process?
De Novo Synthesis of IMP
In simple terms: The cell builds a purine ring from scratch on a ribose phosphate scaffold to make inosine monophosphate (IMP).
The de novo pathway starts with 5-phosphoribosyl-1-pyrophosphate (PRPP) and proceeds through ten enzymatic steps to form IMP, the first purine ribonucleoside monophosphate. This pathway consumes ATP and glutamine and is regulated by feedback inhibition. IMP serves as the branch point for AMP and GMP synthesis.
Conversion of IMP to AMP and GMP
In simple terms: IMP is converted into either AMP or GMP, the two major purine ribonucleoside monophosphates.
IMP is converted to AMP via the sequential action of adenylosuccinate synthetase and adenylosuccinate lyase, and to GMP via IMP dehydrogenase and GMP synthase. These reactions require GTP and ATP, respectively, and are subject to feedback regulation by downstream nucleotides.
Salvage Pathways
In simple terms: The cell recycles purine bases and nucleosides to make nucleotides, saving energy.
Salvage pathways convert free purine bases (hypoxanthine, guanine, adenine) and nucleosides (adenosine, guanosine, inosine) into their corresponding ribonucleoside monophosphates. Key enzymes include hypoxanthine-guanine phosphoribosyltransferase (HGPRT), adenine phosphoribosyltransferase (APRT), and adenosine kinase. These pathways are critical in tissues with high nucleotide demand, such as brain and immune cells.
Phosphorylation of Purine Nucleosides
In simple terms: Nucleosides are phosphorylated by kinases to become monophosphates.
Adenosine kinase phosphorylates adenosine to AMP, and other nucleoside kinases act on guanosine and inosine. This step is a key activation mechanism for nucleoside analogue drugs, such as 6-thioguanine and 6-mercaptopurine, which are converted to their monophosphate forms.
Regulation by Feedback Inhibition
In simple terms: The end products of the pathway inhibit the enzymes that make them, preventing overproduction.
Purine ribonucleoside monophosphates, especially AMP, GMP, and IMP, feedback-inhibit early enzymes of the de novo pathway, such as PRPP amidotransferase. This ensures balanced nucleotide pools and prevents wasteful synthesis.
Key Genes Involved in GO:0009168 purine ribonucleoside monophosphate biosynthetic process
The following genes and proteins are central to purine ribonucleoside monophosphate biosynthetic process, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ADK | Adenosine kinase; phosphorylates adenosine to AMP | Therapeutic target in neurological and inflammatory diseases |
| AMPD | AMP deaminase; converts AMP to IMP | Target for inhibitors designed based on enzyme mechanism |
| ADA | Adenosine deaminase; converts adenosine to inosine | Target for inhibitors; involved in purine metabolism |
| HPRT1 | Hypoxanthine-guanine phosphoribosyltransferase; salvage of hypoxanthine and guanine | Deficiency causes Lesch-Nyhan syndrome; model for purine salvage |
| APRT | Adenine phosphoribosyltransferase; salvage of adenine | Deficiency causes 2,8-dihydroxyadenine urolithiasis |
| IMPDH | Inosine monophosphate dehydrogenase; converts IMP to XMP | Target for immunosuppressive and antiviral drugs |
| GMPS | GMP synthase; converts XMP to GMP | Potential target in cancer and viral infections |
| ADSS | Adenylosuccinate synthetase; converts IMP to adenylosuccinate | Involved in AMP synthesis; potential drug target |
| ADSL | Adenylosuccinate lyase; converts adenylosuccinate to AMP | Deficiency causes adenylosuccinate lyase deficiency |
| PRPS1 | Phosphoribosyl pyrophosphate synthetase 1; produces PRPP | Mutations cause PRPS1 superactivity and gout |
| PPAT | Phosphoribosyl pyrophosphate amidotransferase; first step of de novo pathway | Feedback regulated by purine nucleotides |
| ATIC | AICAR transformylase/IMP cyclohydrolase; final steps of de novo IMP synthesis | Target in cancer chemotherapy |
| GART | Glycinamide ribonucleotide transformylase; de novo pathway | Target in cancer chemotherapy |
| PAICS | Phosphoribosylaminoimidazole carboxylase; de novo pathway | Potential biomarker in cancer |
| PFAS | Phosphoribosylformylglycinamidine synthase; de novo pathway | Target in cancer metabolism |
| NT5C2 | Cytosolic 5'-nucleotidase; dephosphorylates purine ribonucleoside monophosphates | Mutations associated with drug resistance in leukemia |
| SLC29A1 | Equilibrative nucleoside transporter 1; transports nucleosides | Influences drug uptake and metabolism |
How Is purine ribonucleoside monophosphate biosynthetic process Regulated?
Purine ribonucleoside monophosphate biosynthetic process is regulated at multiple levels. Feedback inhibition by end products (AMP, GMP, IMP) controls the committed step of de novo synthesis, catalyzed by PRPP amidotransferase. Enzyme expression is regulated in response to cellular nucleotide demand, and salvage pathways are modulated by substrate availability and nucleoside transporters. Adenosine kinase activity is regulated by phosphorylation and by cellular energy status, influencing adenosine and AMP levels. Inhibitors of AMP deaminase and adenosine deaminase are designed to modulate flux through the pathway. Additionally, antimetabolite drugs such as 6-thioguanine and 6-mercaptopurine are activated by the pathway and can feedback-inhibit enzymes, leading to growth arrest.
purine ribonucleoside monophosphate biosynthetic process and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ADK | Epilepsy, pain, inflammation | Adk knockout mice; point mutation models |
| HPRT1 | Lesch-Nyhan syndrome | HPRT1 knockout cell lines and mice |
| IMPDH | Cancer, viral infections | IMPDH knockout or knockdown cells; inhibitor studies |
| NT5C2 | Drug resistance in leukemia | NT5C2 mutant knock-in cell lines |
| PRPS1 | Gout, PRPS1 superactivity | PRPS1 overexpression or point mutation models |
Cancer and Antimetabolite Therapy
Purine ribonucleoside monophosphate biosynthetic process is essential for cancer cell proliferation because it supplies nucleotides for DNA and RNA synthesis. Antimetabolites such as 6-thioguanine, 6-mercaptopurine, and 8-azaguanine are prodrugs that require conversion to their ribonucleoside monophosphate forms to inhibit downstream enzymes and incorporate into nucleic acids, causing cytotoxicity. Resistance to these drugs often involves alterations in the pathway, such as decreased enzyme activity or increased nucleotide degradation.
Viral Infections
Purine ribonucleoside monophosphates can directly inhibit viral DNA polymerases. For example, purine ribonucleoside monophosphates inhibit herpes simplex virus DNA polymerase, suggesting a mechanism for antiviral activity. Additionally, nucleoside analogues used as antivirals are phosphorylated by cellular kinases to their monophosphate forms, which then inhibit viral replication.
Neurological and Inflammatory Disorders
Adenosine kinase regulates adenosine and AMP levels, which modulate neurotransmission and inflammation. Inhibition of adenosine kinase is being explored for therapeutic gain in epilepsy, pain, and inflammatory diseases. Dysregulation of purine metabolism has also been linked to neurodegenerative conditions through altered adenosine signaling.
Cardiovascular and Renal Diseases
Gene co-expression network analysis identified purine ribonucleoside monophosphate biosynthetic pathways as associated with hypertrophic cardiomyopathy. Metabolomic network analysis of membranous glomerulonephritis also implicated purine metabolism, suggesting a role in renal disease.
From purine ribonucleoside monophosphate biosynthetic process-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of ADK alter adenosine and AMP levels? | ADK knockout cell line or mouse model |
| How do point mutations in HPRT1 affect salvage pathway flux? | HPRT1 point mutation knock-in cells |
| Can overexpression of IMPDH increase resistance to antimetabolites? | IMPDH overexpression cell line |
| What is the effect of NT5C2 mutations on drug sensitivity? | NT5C2 mutant knock-in leukemia cells |
| Does tagging of AMPD reveal its subcellular localization? | AMPD tagged knock-in cells |
| Can CRISPR library screening identify genes required for purine ribonucleoside monophosphate synthesis? | Genome-wide CRISPR knockout library in cancer cell lines |
How to Study the purine ribonucleoside monophosphate biosynthetic process Process
| Method | What It Measures | Typical Application |
|---|---|---|
| LC-MS metabolomics | Levels of purine ribonucleoside monophosphates and intermediates | Quantifying pathway flux in cells and tissues |
| Stable isotope tracing | Flux through de novo and salvage pathways | Determining pathway activity in cancer cells |
| Enzyme activity assay | Kinetic parameters and inhibition of pathway enzymes | Drug screening and mutant characterization |
| CRISPR knockout screen | Genes required for pathway function or drug resistance | Identifying therapeutic targets |
| RNA-seq | Gene expression changes in pathway enzymes | Transcriptomic profiling of disease models |
| Co-expression network analysis | Functional relationships between pathway genes and disease | Identifying disease-associated pathways |
| Nucleoside transport assay | Uptake of nucleosides and analogues | Studying drug transport and resistance |
| Western blot | Protein expression of pathway enzymes | Validating knockout or overexpression models |
Metabolomics and Flux Analysis
Liquid chromatography-mass spectrometry (LC-MS) can quantify purine ribonucleoside monophosphates and their intermediates. Stable isotope tracing with 13C-glucose or 15N-glutamine allows flux analysis through the pathway.
Enzyme Activity Assays
Enzymatic assays measure the activity of adenosine kinase, AMP deaminase, and other enzymes using radiolabeled or fluorescent substrates. These assays are used to evaluate inhibitors and to characterize mutant enzymes.
CRISPR-Cas9 Knockout Screening
Genome-wide CRISPR knockout screens can identify genes essential for purine ribonucleoside monophosphate biosynthesis and for resistance to antimetabolites. This approach has been used to uncover drug resistance mechanisms.
RNA-seq and Co-expression Network Analysis
RNA sequencing followed by co-expression network analysis can reveal pathways associated with disease. For example, co-expression analysis linked purine metabolism to hypertrophic cardiomyopathy.
How CRISPR Can Be Used to Study GO:0009168 purine ribonucleoside monophosphate biosynthetic process
Knockout
CRISPR-Cas9 knockout of genes such as ADK, HPRT1, or IMPDH can abolish specific steps in purine ribonucleoside monophosphate biosynthesis, allowing researchers to study pathway dependencies and compensatory mechanisms.
Point Mutation
Introducing point mutations that mimic human disease variants, such as in HPRT1 or NT5C2, enables functional studies of enzyme activity and drug resistance in isogenic cell lines.
Knock-in
Knock-in of tagged versions of enzymes like AMPD or ADK allows for localization and interaction studies using fluorescence or affinity purification.
Overexpression
Overexpression of rate-limiting enzymes such as IMPDH or PRPS1 can increase flux through the pathway and model conditions of nucleotide overproduction, such as gout or cancer.
How EDITGENE Supports purine ribonucleoside monophosphate biosynthetic process Research
Researchers studying purine ribonucleoside monophosphate biosynthetic process-related genes often need to determine whether a candidate gene is causally involved in pathway regulation, drug response, or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to enable these investigations with high precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for purine ribonucleoside monophosphate biosynthetic process research.
Frequently Asked Questions About purine ribonucleoside monophosphate biosynthetic process
What is GO:0009168?
GO:0009168 is the Gene Ontology term for purine ribonucleoside monophosphate biosynthetic process, the set of reactions that produce purine ribonucleoside monophosphates such as AMP, GMP, and IMP.
What genes are involved in purine ribonucleoside monophosphate biosynthetic process?
Key genes include ADK, AMPD, ADA, HPRT1, APRT, IMPDH, GMPS, ADSS, ADSL, PRPS1, PPAT, ATIC, GART, PAICS, PFAS, and NT5C2.
How is purine ribonucleoside monophosphate biosynthetic process regulated?
It is regulated by feedback inhibition of early enzymes by end products like AMP and GMP, and by enzyme expression and substrate availability.
What diseases are associated with purine ribonucleoside monophosphate biosynthetic process?
It is linked to cancer, viral infections, neurological disorders, hypertrophic cardiomyopathy, and membranous glomerulonephritis.
What drugs target purine ribonucleoside monophosphate biosynthetic process?
Antimetabolites such as 6-thioguanine, 6-mercaptopurine, and 8-azaguanine are prodrugs activated by this pathway.
How can I study purine ribonucleoside monophosphate biosynthetic process in the lab?
Common methods include LC-MS metabolomics, enzyme activity assays, CRISPR knockout screens, and RNA-seq.
What is the role of adenosine kinase in this pathway?
Adenosine kinase phosphorylates adenosine to AMP and is a therapeutic target in neurological and inflammatory diseases.
Can purine ribonucleoside monophosphates inhibit viral polymerases?
Yes, purine ribonucleoside monophosphates have been shown to inhibit herpes simplex virus DNA polymerase.
What CRISPR models are available for studying this pathway?
Knockout, point mutation, knock-in, and overexpression models can be generated for genes like ADK, HPRT1, and IMPDH.
Why is purine ribonucleoside monophosphate biosynthesis important for cancer research?
Cancer cells require high nucleotide levels for proliferation, and antimetabolite drugs target this pathway.
Conclusion
Purine ribonucleoside monophosphate biosynthetic process (GO:0009168) is a central metabolic pathway that supplies the nucleotide building blocks for nucleic acid synthesis and serves as the activation route for important antimetabolite and antiviral drugs. Its dysregulation is implicated in cancer, viral infections, neurological disorders, and cardiovascular and renal diseases. Understanding the genes, enzymes, and regulatory mechanisms of this pathway is essential for developing new therapeutic strategies. EDITGENE provides advanced CRISPR tools to facilitate functional studies of this pathway in relevant disease models.
References
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- 4. Frank KB et al.. 1986. Inhibition of herpes simplex virus DNA polymerase by purine ribonucleoside monophosphates.. J Biol Chem 261(4):1510-3 PMID: 3003073
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- 7. el Kouni MH et al.. 1987. Metabolism of adenosine analogues by Schistosoma mansoni and the effect of nucleoside transport inhibitors.. Biochem Pharmacol 36(7):1099-106 PMID: 3566804
- 8. Chen XM et al.. 2017. A novel approach to select differential pathways associated with hypertrophic cardiomyopathy based on gene co‑expression analysis.. Mol Med Rep 16(1):773-777 PMID: 28586052
