GO:0000255 allantoin metabolic process: Purine Catabolism Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0000255 allantoin metabolic process describes the chemical reactions and pathways involving allantoin, a key intermediate or end product of purine catabolism.
• Allantoin is produced from uric acid by urate oxidase and is further degraded to allantoate by allantoinase in organisms ranging from bacteria to plants.
• In enterobacteria, allantoin metabolism is tightly regulated and supports anaerobic growth by providing nitrogen and carbon sources.
• In legumes, allantoin serves as a major nitrogen transport and storage compound, and its degradation is essential for nitrogen remobilization.
• Allantoin is a widely used biomarker of oxidative stress in humans, reflecting free radical damage to purines.
• CRISPR-based knockout, knock-in, and overexpression models are powerful tools to dissect the genetic control of allantoin metabolic process.
Description
Allantoin metabolic process (GO:0000255) encompasses the chemical reactions and pathways involving allantoin, (2,5-dioxo-4-imidazolidinyl)urea, an intermediate or end product of purine catabolism. Allantoin is formed from uric acid by urate oxidase and is further degraded to allantoate by allantoinase in many organisms, including bacteria, fungi, and plants. In enterobacteria, allantoin can serve as a nitrogen and carbon source under anaerobic conditions, and its metabolism is tightly regulated. In legumes, allantoin is a major ureide transported in xylem and is critical for nitrogen remobilization during seed development. In humans, allantoin is a stable end product of purine oxidation and is excreted in urine, where it serves as a biomarker of oxidative stress. Understanding allantoin metabolic process is therefore relevant to microbial physiology, plant nitrogen metabolism, and human oxidative stress research.
allantoin metabolic process At A Glance
| GO ID | GO:0000255 |
|---|---|
| GO term | allantoin metabolic process |
| Ontology | biological_process |
| Synonym | allantoin metabolism |
| Major function | Purine catabolism; nitrogen utilization; oxidative stress biomarker production |
| Definition | The chemical reactions and pathways involving allantoin, (2,5-dioxo-4-imidazolidinyl)urea, an intermediate or end product of purine catabolism. |
| Related enzymes | Urate oxidase, allantoinase, allantoate amidohydrolase |
| Organisms | Bacteria, fungi, plants, and mammals (as end product) |
What Is GO:0000255?
GO:0000255 allantoin metabolic process is defined as the chemical reactions and pathways involving allantoin, (2,5-dioxo-4-imidazolidinyl)urea, an intermediate or end product of purine catabolism. This process includes the synthesis of allantoin from uric acid and its subsequent degradation to allantoate and other downstream metabolites, as well as the transport and utilization of allantoin as a nitrogen source in various organisms.
Why Is allantoin metabolic process Important in Cell Biology?
Allantoin metabolic process is important because it sits at the crossroads of purine catabolism and nitrogen metabolism across all domains of life. In enterobacteria, it enables the use of allantoin as a nitrogen source during anaerobic growth, which is critical for colonization and survival in host environments. In legumes, allantoin is a major transport form of fixed nitrogen, and its degradation is essential for seed development and nitrogen remobilization. In humans, allantoin is a stable product of free radical oxidation of uric acid and is widely used as a biomarker of oxidative stress, linking this pathway to aging, inflammation, and chronic diseases. Moreover, the enzymes involved in allantoin metabolism are potential targets for antimicrobial and herbicide development, and their study informs metabolic engineering for allantoin production.
• Allantoin is a key intermediate in purine catabolism, connecting nucleotide turnover to nitrogen excretion.
• In enterobacteria, allantoin metabolism supports anaerobic growth and host colonization.
• In legumes, allantoin is a major nitrogen transport compound essential for seed development.
• Allantoin is a widely used urinary biomarker of oxidative stress in humans.
• Dysregulated purine catabolism is linked to hyperuricemia, gout, and cardiovascular disease.
• Allantoin metabolism enzymes are potential targets for antimicrobials and herbicides.
• Microbial allantoin degradation is a model system for gene regulation and metabolic integration.
• Engineering allantoin biosynthesis in E. coli has biotechnological applications.
• Allantoin metabolism intersects with reactive oxygen species detoxification.
• CRISPR screens can identify novel regulators of allantoin metabolic process.
What Happens During allantoin metabolic process?
Formation of allantoin from uric acid
In simple terms: Uric acid is converted into allantoin by an enzyme called urate oxidase.
In many organisms, allantoin is synthesized from uric acid through the action of urate oxidase (also known as uricase). This enzyme catalyzes the oxidation of uric acid to 5-hydroxyisourate, which then spontaneously or enzymatically converts to allantoin. In Escherichia coli, heterologous expression of urate oxidase enables allantoin biosynthesis, and screening of highly effective urate oxidases has been used to enhance production. In humans, urate oxidase is non-functional, so uric acid is not converted to allantoin; instead, allantoin is formed non-enzymatically from uric acid oxidation by free radicals.
Degradation of allantoin to allantoate
In simple terms: Allantoin is broken down into allantoate by the enzyme allantoinase.
Allantoinase catalyzes the hydrolysis of allantoin to allantoate. In E. coli, allantoinase is activated by the downstream metabolic enzyme glycerate kinase, which also stabilizes the putative allantoin transporter by direct binding. This coordination ensures efficient allantoin utilization. In Saccharomyces cerevisiae, allantoin degradation is a model system for gene regulation and metabolic integration, where allantoinase and subsequent enzymes are induced by allantoin and regulated by nitrogen catabolite repression.
Further degradation to glyoxylate and urea
In simple terms: Allantoate is further broken down into simpler molecules that can be used by the cell.
Allantoate is subsequently degraded by allantoate amidohydrolase to ureidoglycolate and urea, and further to glyoxylate and ammonia. In legumes, this pathway is essential for the degradation of ureides (allantoin and allantoic acid) during nitrogen remobilization. In enterobacteria, the complete degradation of allantoin to ammonia and glyoxylate allows the use of allantoin as a nitrogen source under anaerobic conditions.
Transport and regulation of allantoin metabolism
In simple terms: Cells take up allantoin from the environment and regulate its metabolism based on need.
Allantoin transport is mediated by specific transporters, such as the putative allantoin transporter in E. coli, which is stabilized by direct binding to glycerate kinase. In enterobacteria, the expression of allantoin metabolism genes is regulated by the availability of nitrogen and the presence of allantoin, often through global regulators like the nitrogen regulatory protein C (NtrC). In yeast, allantoin degradation is subject to nitrogen catabolite repression, ensuring that allantoin is used only when preferred nitrogen sources are scarce.
Key Genes Involved in GO:0000255 allantoin metabolic process
The following genes and proteins are central to allantoin metabolic process across model organisms.
| Gene | Major Role | Research Relevance |
|---|---|---|
| allB (E. coli) | Allantoinase, hydrolyzes allantoin to allantoate | Model for enzyme activation and transporter stabilization |
| allA (E. coli) | Allantoate amidohydrolase, degrades allantoate | Nitrogen utilization under anaerobic conditions |
| allD (E. coli) | Ureidoglycolate dehydrogenase | Complete allantoin degradation pathway |
| allE (E. coli) | Ureidoglycolate lyase | Production of glyoxylate and ammonia |
| allC (E. coli) | Allantoin transporter | Uptake of allantoin; stabilized by glycerate kinase |
| garK (E. coli) | Glycerate kinase, activates allantoinase | Regulatory interaction with allantoinase |
| uaZ (E. coli) | Urate oxidase | Biosynthesis of allantoin from uric acid |
| DAL1 (S. cerevisiae) | Allantoinase | Model for gene regulation and metabolic integration |
| DAL2 (S. cerevisiae) | Allantoate amidohydrolase | Allantoin degradation pathway |
| DAL3 (S. cerevisiae) | Ureidoglycolate hydrolase | Downstream degradation |
| DAL4 (S. cerevisiae) | Allantoin permease | Transport of allantoin |
| DAL7 (S. cerevisiae) | Malate synthase | Glyoxylate cycle integration |
| DAL80 (S. cerevisiae) | Transcriptional repressor | Nitrogen catabolite repression |
| UOX (plants) | Urate oxidase | Allantoin biosynthesis in legumes |
| ALN (plants) | Allantoinase | Ureide degradation in legumes |
| AAH (plants) | Allantoate amidohydrolase | Nitrogen remobilization |
| UPS1 (plants) | Ureide permease | Transport of allantoin |
How Is allantoin metabolic process Regulated?
Allantoin metabolic process is regulated at multiple levels. In enterobacteria, the expression of allantoin utilization genes is controlled by nitrogen availability and induced by allantoin, often through the NtrC regulon. In Saccharomyces cerevisiae, allantoin degradation is subject to nitrogen catabolite repression, where DAL80 represses gene expression in the presence of preferred nitrogen sources. In E. coli, allantoinase activity is post-translationally activated by glycerate kinase, which also stabilizes the allantoin transporter, providing a direct link between allantoin degradation and downstream metabolism. In plants, ureide degradation is developmentally regulated and responds to nitrogen demand during seed filling.
allantoin metabolic process and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| UOX (human) | Hyperuricemia and gout due to urate oxidase deficiency | Uox knockout mouse; knock-in of functional UOX |
| allB (E. coli) | Bacterial nitrogen utilization and colonization | allB knockout in E. coli; anaerobic growth assays |
| DAL80 (S. cerevisiae) | Nitrogen catabolite repression and metabolic regulation | DAL80 deletion and overexpression in yeast |
| ALN (plants) | Nitrogen remobilization and seed development | ALN knockout in legumes; seed nitrogen content analysis |
| UA (uric acid) | Oxidative stress and inflammation | Cell models with urate oxidase overexpression; allantoin measurement |
Allantoin as a biomarker of oxidative stress in human disease
Allantoin is a stable end product of free radical oxidation of uric acid and is widely used as a urinary biomarker of oxidative stress. Elevated allantoin levels have been associated with conditions such as diabetes, cardiovascular disease, and aging, reflecting increased reactive oxygen species production. Because allantoin is not further metabolized in humans, its measurement provides an integrated index of oxidative damage to purines.
Disorders of purine catabolism and hyperuricemia
In humans, the absence of functional urate oxidase leads to the accumulation of uric acid, which can cause hyperuricemia and gout. Allantoin is not produced enzymatically in humans but is formed non-enzymatically from uric acid, and its levels can reflect purine catabolic flux. Understanding allantoin metabolism in model organisms informs the development of therapies for purine-related disorders.
Microbial allantoin metabolism and host colonization
Enterobacteria such as E. coli can utilize allantoin as a nitrogen source under anaerobic conditions, which may contribute to their survival in the host gut. The allantoin degradation pathway is therefore a potential target for antimicrobial strategies aimed at limiting bacterial growth in anaerobic niches. The regulation of allantoin metabolism in enterobacteria is a model for understanding metabolic adaptation during infection.
From allantoin metabolic process-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does allB (allantoinase) loss affect anaerobic growth? | allB knockout in E. coli |
| Can allantoin production be enhanced by urate oxidase engineering? | Overexpression of urate oxidase in E. coli |
| How does glycerate kinase regulate allantoinase activity? | Point mutations in garK; protein-protein interaction assays |
| What is the role of DAL80 in nitrogen catabolite repression? | DAL80 knockout and tagged knock-in in S. cerevisiae |
| Does allantoin transport affect nitrogen remobilization in legumes? | Knockout of ureide permease in legumes |
| Can allantoin be used as a biomarker for oxidative stress? | Human cell models with oxidative stress inducers; allantoin quantification |
How to Study the allantoin metabolic process Process
| Method | What It Measures | Typical Application |
|---|---|---|
| HPLC | Allantoin concentration | Quantification in urine or culture media |
| Enzyme activity assay | Allantoinase or urate oxidase activity | Characterization of purified enzymes |
| RNA-seq | Transcript levels of allantoin metabolism genes | Regulation studies in bacteria and yeast |
| Proteomics | Protein abundance and interactions | Identifying allantoinase-binding partners |
| Metabolomics (LC-MS/GC-MS) | Allantoin and downstream metabolites | Flux analysis in engineered strains |
| CRISPR knockout screen | Genes required for allantoin utilization | Functional genomics in E. coli |
| 15N-isotope tracing | Nitrogen flux from allantoin | Plant nitrogen remobilization studies |
| Reporter gene assay | Promoter activity of DAL genes | Nitrogen catabolite repression in yeast |
Genetic and biochemical assays for allantoin metabolism
Classical methods to study allantoin metabolic process include enzymatic assays measuring allantoinase and urate oxidase activities, high-performance liquid chromatography (HPLC) for allantoin quantification, and growth assays using allantoin as a sole nitrogen source. In E. coli, the activation of allantoinase by glycerate kinase can be assessed by in vitro reconstitution and binding assays. In yeast, reporter gene fusions to DAL promoters are used to study nitrogen catabolite repression.
Transcriptomics and proteomics
RNA-seq and proteomics can reveal global changes in gene expression when cells are grown on allantoin versus preferred nitrogen sources. In enterobacteria, transcriptomic profiling has identified the allantoin regulon and its regulation by NtrC. In plants, transcriptome analysis during seed development has highlighted ureide degradation genes.
Metabolomics and flux analysis
Metabolomics approaches, such as GC-MS and LC-MS, allow quantification of allantoin and its downstream metabolites (allantoate, ureidoglycolate, glyoxylate) to assess pathway flux. Isotope tracing with 15N-labeled allantoin can determine nitrogen utilization efficiency in bacteria and plants.
CRISPR screening and functional genomics
CRISPR knockout libraries can be used to identify genes required for allantoin utilization in bacteria or for allantoin production in engineered strains. In human cells, CRISPR screens can uncover regulators of oxidative stress that influence allantoin levels. These functional genomics approaches accelerate the discovery of novel components in allantoin metabolic process.
How CRISPR Can Be Used to Study GO:0000255 allantoin metabolic process
Knockout
CRISPR knockout of allantoin metabolism genes, such as allB in E. coli or DAL1 in S. cerevisiae, enables the study of pathway necessity and the accumulation of intermediates. In human cell models, knockout of urate oxidase (though non-functional) or other purine catabolic genes can help dissect oxidative stress pathways.
Point Mutation
Point mutations can be introduced into catalytic residues of allantoinase or urate oxidase to study enzyme mechanism and substrate specificity. For example, mutating the active-site residues of E. coli allantoinase can reveal their role in catalysis and activation by glycerate kinase.
Knock-in
Knock-in of tagged versions of allantoin metabolism enzymes (e.g., GFP or FLAG tags) allows visualization and immunoprecipitation to study localization and interactions. In plants, knock-in of ureide permease with a fluorescent tag can track allantoin transport in vivo.
Overexpression
Overexpression of urate oxidase in E. coli or other hosts can enhance allantoin biosynthesis for biotechnological production. Overexpression of allantoinase or downstream enzymes can increase allantoin degradation flux and nitrogen release. In human cells, overexpression of antioxidant enzymes can modulate allantoin levels under oxidative stress.
How EDITGENE Supports allantoin metabolic process Research
Researchers studying allantoin metabolic process-related genes often need to determine whether a candidate gene is causally involved in pathway regulation, metabolite production, or disease-associated oxidative stress. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for functional validation.
Contact EDITGENE today to design your custom CRISPR model for allantoin metabolic process research.
Frequently Asked Questions About allantoin metabolic process
What is allantoin metabolic process?
Allantoin metabolic process (GO:0000255) is the set of chemical reactions and pathways involving allantoin, an intermediate or end product of purine catabolism.
What genes are involved in allantoin metabolic process?
Key genes include allB (allantoinase), allA, allD, allE, and allC in E. coli; DAL1-DAL4 and DAL80 in yeast; and UOX, ALN, AAH, and UPS1 in plants.
What is the function of allantoinase?
Allantoinase catalyzes the hydrolysis of allantoin to allantoate, a key step in allantoin degradation.
How is allantoin produced?
Allantoin is produced from uric acid by urate oxidase in many organisms, or non-enzymatically from uric acid oxidation by free radicals in humans.
Why is allantoin a biomarker of oxidative stress?
Allantoin is a stable end product of free radical oxidation of uric acid and is excreted in urine, reflecting oxidative damage.
What diseases are associated with allantoin metabolism?
Dysregulated purine catabolism is linked to hyperuricemia, gout, and cardiovascular disease; allantoin levels are associated with oxidative stress-related conditions.
How can CRISPR be used to study allantoin metabolism?
CRISPR knockout, knock-in, and overexpression can create isogenic cell models to test the function of allantoin metabolism genes in bacteria, yeast, plants, and human cells.
What model organisms are used to study allantoin metabolic process?
Escherichia coli, Saccharomyces cerevisiae, legumes, and mammalian cell lines are commonly used.
What is the role of glycerate kinase in allantoin metabolism?
Glycerate kinase activates allantoinase and stabilizes the allantoin transporter by direct binding in E. coli.
Can allantoin be used as a nitrogen source?
Yes, many bacteria and plants can utilize allantoin as a nitrogen source through its degradation to ammonia and glyoxylate.
Conclusion
Allantoin metabolic process (GO:0000255) is a conserved pathway at the interface of purine catabolism and nitrogen utilization, with critical roles in microbial physiology, plant nitrogen remobilization, and human oxidative stress biology. The enzymes and transporters involved, such as allantoinase, urate oxidase, and glycerate kinase, are attractive targets for functional studies and biotechnological applications. CRISPR-based genome editing provides a robust toolkit to dissect the genetic control of this pathway and to develop models for drug discovery and metabolic engineering.
References
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- 6. Rodionova IA et al.. 2023. E. coli allantoinase is activated by the downstream metabolic enzyme, glycerate kinase, and stabilizes the putative allantoin transporter by direct binding.. Sci Rep 13(1):7345 PMID: 37147430
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