GO:0004020 adenylylsulfate kinase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004020 adenylylsulfate kinase activity catalyzes the phosphorylation of adenosine 5'-phosphosulfate (APS) to 3'-phosphoadenylyl sulfate (PAPS), the universal sulfate donor for sulfotransferases.
• The enzyme is a member of the APS kinase family and is often fused to ATP-sulfurylase in bifunctional PAPS synthase enzymes in higher eukaryotes.
• Defects in adenylylsulfate kinase activity cause impaired PAPS formation, as seen in brachymorphic mice, leading to skeletal abnormalities.
• Human PAPS synthase 2 (PAPSS2) contains an APS kinase domain whose activity is regulated by redox switching, linking sulfate activation to cellular redox state.
• Structural studies of APS kinase from Archaeoglobus fulgidus reveal a conserved catalytic core with a P-loop ATP-binding motif and a flexible lid region.
• CRISPR-based knockout, point mutation, and knock-in models are essential to dissect the role of adenylylsulfate kinase in sulfation-related diseases and metabolic pathways.
Description
Adenylylsulfate kinase activity (GO:0004020) is a molecular function that catalyzes the transfer of a phosphate group from ATP to adenosine 5'-phosphosulfate (APS), yielding 3'-phosphoadenylyl sulfate (PAPS) and ADP. This reaction is the second step in the sulfate activation pathway, which is essential for the biosynthesis of PAPS, the primary sulfate donor for all sulfotransferase reactions in cells. The enzyme is widely distributed from bacteria to humans and is critical for the sulfation of glycoproteins, glycosaminoglycans, steroids, and xenobiotics. Researchers study adenylylsulfate kinase activity to understand sulfur metabolism, developmental processes, and diseases linked to defective sulfation, such as skeletal dysplasias and metabolic disorders. The enzyme has been purified from liver and characterized biochemically, and its bifunctional organization with ATP-sulfurylase in higher organisms has been extensively investigated. Recent structural and mechanistic studies have provided insights into its catalytic mechanism and regulation, including redox-dependent control of the human PAPS synthase 2 APS kinase domain.
adenylylsulfate kinase activity At A Glance
| GO ID | GO:0004020 |
|---|---|
| GO term | adenylylsulfate kinase activity |
| Ontology | molecular_function |
| Synonym | APS kinase activity; adenosine 5'-phosphosulfate kinase activity; adenylyl-sulfate kinase activity; ATP:adenylyl-sulfate 3'-phosphotransferase activity |
| Major function | Catalyzes the phosphorylation of APS to PAPS, the universal sulfate donor |
| Reaction | adenosine 5'-phosphosulfate + ATP = 3'-phosphoadenylyl sulfate + ADP + H+ |
| EC number | 2.7.1.25 |
| Pathway | Sulfate activation pathway (PAPS biosynthesis) |
| Cellular location | Cytosol; in higher eukaryotes, often part of bifunctional PAPS synthase enzymes |
What Is GO:0004020?
According to the Gene Ontology, adenylylsulfate kinase activity (GO:0004020) is defined as the catalysis of the reaction: adenosine 5'-phosphosulfate + ATP = 3'-phosphoadenylyl sulfate + ADP + H+. In other words, it is the enzyme activity that phosphorylates APS at the 3'-position to produce PAPS, consuming one molecule of ATP and releasing ADP and a proton. This activity is synonymous with APS kinase activity, adenylyl-sulfate kinase activity, and several other names listed in the GO synonyms.
Why Is adenylylsulfate kinase activity Important in Cell Biology?
Adenylylsulfate kinase activity is essential for the production of PAPS, which is required for all sulfation reactions in the body. Sulfation is critical for the detoxification of drugs and xenobiotics, the biosynthesis of glycosaminoglycans and sulfolipids, and the modulation of hormone activity. Defects in this activity lead to impaired sulfation, as demonstrated in brachymorphic mice, which have a defect in PAPS formation and exhibit skeletal abnormalities. In humans, mutations in the bifunctional PAPS synthase 2 (PAPSS2) gene, which contains the APS kinase domain, cause spondyloepimetaphyseal dysplasia and other skeletal disorders. Therefore, understanding adenylylsulfate kinase activity is crucial for developmental biology, pharmacology, and metabolic disease research.
• Provides PAPS for sulfotransferases, which modify hormones, neurotransmitters, and drugs.
• Essential for the biosynthesis of sulfated glycosaminoglycans in cartilage and connective tissue.
• Defects cause skeletal dysplasia in mice and humans.
• Involved in detoxification of xenobiotics and endogenous compounds.
• Regulated by redox state in human PAPS synthase 2, linking sulfate activation to cellular redox balance.
• Target for understanding sulfur metabolism disorders and potential therapeutic interventions.
• Bifunctional organization with ATP-sulfurylase in higher eukaryotes enables coordinated sulfate activation.
• Structural studies provide a basis for inhibitor design and mechanistic insights.
What Happens During adenylylsulfate kinase activity?
Substrate binding and catalysis
In simple terms: The enzyme grabs APS and ATP, then transfers a phosphate from ATP to APS.
Adenylylsulfate kinase binds adenosine 5'-phosphosulfate (APS) and ATP in a sequential manner. The enzyme catalyzes the transfer of the gamma-phosphate of ATP to the 3'-hydroxyl group of APS, forming 3'-phosphoadenylyl sulfate (PAPS) and ADP. This reaction is the second step in the sulfate activation pathway, following the formation of APS by ATP-sulfurylase. The catalytic mechanism involves a conserved P-loop motif for ATP binding and a flexible lid region that undergoes conformational changes upon substrate binding.
Structural basis of catalysis
In simple terms: The enzyme has a specific shape that holds the molecules in place for the reaction.
Crystal structures of APS kinase from Archaeoglobus fulgidus reveal a dimeric arrangement with each monomer containing a central beta-sheet flanked by alpha-helices. The active site includes a P-loop for ATP binding and a conserved arginine residue that stabilizes the transition state. In human PAPS synthase 2, the APS kinase domain (APSK2) undergoes a redox-dependent conformational switch that regulates its activity, involving a disulfide bond between cysteine residues.
Bifunctional enzyme organization
In simple terms: In higher organisms, the enzyme is often joined with another enzyme that makes APS, so the two steps happen together.
In higher eukaryotes, adenylylsulfate kinase activity is often part of a bifunctional enzyme, PAPS synthase, which also contains ATP-sulfurylase activity. This fusion allows channeling of APS from the sulfurylase domain to the kinase domain, enhancing the efficiency of PAPS production. Recombinant bifunctional and monofunctional domains have been studied to understand the kinetic advantages of this arrangement.
Role in PAPS biosynthesis and sulfation
In simple terms: The product PAPS is used by other enzymes to add sulfate groups to many molecules.
The PAPS produced by adenylylsulfate kinase is the universal sulfate donor for all sulfotransferase reactions. These reactions sulfate a wide range of substrates, including glycosaminoglycans, steroids, neurotransmitters, and xenobiotics. Defects in PAPS formation lead to impaired sulfation, as seen in brachymorphic mice, which have a mutation in the APS kinase domain of PAPS synthase 2 and exhibit skeletal abnormalities due to undersulfated cartilage proteoglycans.
Key Genes Involved in GO:0004020 adenylylsulfate kinase activity
The following genes and proteins are directly involved in adenylylsulfate kinase activity or its regulation.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PAPSS1 | Bifunctional enzyme with ATP-sulfurylase and APS kinase domains; produces PAPS | Studied for PAPS synthesis in various tissues; knockout models show impaired sulfation |
| PAPSS2 | Bifunctional enzyme; APS kinase domain (APSK2) regulated by redox | Mutations cause skeletal dysplasia; redox regulation studied |
| PAPSS2 (APSK2 domain) | Isolated APS kinase domain of human PAPSS2 | Used to study redox switching and catalytic mechanism |
| ATP6V1A | Vacuolar ATPase subunit; indirectly affects sulfate transport | Potential modifier of sulfate activation |
| SLC26A1 | Sulfate transporter | Involved in sulfate uptake for PAPS synthesis |
| SLC26A2 | Sulfate transporter | Mutations cause diastrophic dysplasia; affects sulfate supply |
| SULT1A1 | Sulfotransferase using PAPS | Downstream consumer of PAPS; studied in detoxification |
| SULT2A1 | Sulfotransferase using PAPS | Involved in steroid sulfation |
| CHST3 | Chondroitin 6-sulfotransferase | Uses PAPS for glycosaminoglycan sulfation |
| CHST14 | Dermatan 4-sulfotransferase | Uses PAPS; mutations cause Ehlers-Danlos syndrome |
| UST | Uronyl 2-sulfotransferase | Uses PAPS in glycosaminoglycan biosynthesis |
| HS6ST1 | Heparan sulfate 6-sulfotransferase | Uses PAPS; involved in development |
| NDST1 | N-deacetylase/N-sulfotransferase | Uses PAPS for heparan sulfate modification |
| TPST1 | Tyrosylprotein sulfotransferase | Uses PAPS for protein tyrosine sulfation |
| TPST2 | Tyrosylprotein sulfotransferase | Uses PAPS for protein tyrosine sulfation |
| GAL3ST1 | Galactose-3-O-sulfotransferase | Uses PAPS for sulfolipid synthesis |
| PAPSS2 (mouse) | Mouse ortholog of PAPSS2 | Brachymorphic mice have a mutation in this gene |
| APS kinase (A. fulgidus) | Archaeal APS kinase | Used for structural studies |
How Is adenylylsulfate kinase activity Regulated?
Adenylylsulfate kinase activity is regulated at multiple levels. In human PAPS synthase 2, the APS kinase domain (APSK2) undergoes a redox-dependent conformational switch: under oxidizing conditions, a disulfide bond forms that inhibits activity, while reducing conditions activate the enzyme. This redox regulation links sulfate activation to the cellular redox state. Additionally, the bifunctional organization with ATP-sulfurylase allows channeling of the intermediate APS, which may regulate flux through the pathway. Expression of PAPSS1 and PAPSS2 is tissue-specific and developmentally regulated, influencing PAPS availability for sulfation reactions.
adenylylsulfate kinase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PAPSS2 | Spondyloepimetaphyseal dysplasia; skeletal abnormalities | Knockout or point-mutation mouse models; patient-derived iPSCs |
| PAPSS1 | Potential role in sulfate homeostasis; not directly linked to disease | Knockout cell lines; overexpression studies |
| SLC26A2 | Diastrophic dysplasia; sulfate transport defect | Knockout mice; transport assays |
| SULT2A1 | Steroid sulfation disorders | Knockout models; enzyme activity assays |
| CHST3 | Chondrodysplasia with joint dislocations | Knockout mice; chondrocyte cultures |
Skeletal dysplasia and brachymorphic mice
Mutations in the APS kinase domain of PAPS synthase 2 cause impaired PAPS formation, leading to undersulfated cartilage proteoglycans and skeletal abnormalities. The brachymorphic mouse, which has a defect in PAPS formation, exhibits a short-limbed dwarfism phenotype. In humans, mutations in PAPSS2 cause spondyloepimetaphyseal dysplasia, a skeletal disorder characterized by short stature and joint abnormalities.
Metabolic and detoxification disorders
Adenylylsulfate kinase activity is essential for PAPS production, which is required for the sulfation and detoxification of drugs, hormones, and xenobiotics. Impaired PAPS synthesis can lead to altered drug metabolism and increased toxicity. Conditions affecting sulfate transport or activation may exacerbate these effects.
Cancer and sulfation
Altered sulfation patterns are observed in various cancers, affecting cell signaling and extracellular matrix remodeling. PAPS levels, controlled by adenylylsulfate kinase activity, can influence the sulfation of growth factors and receptors, thereby impacting tumor progression. However, direct evidence linking APS kinase mutations to cancer is limited and requires further research.
From adenylylsulfate kinase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of PAPSS2 knockout on sulfation and development? | Knockout mouse or cell line |
| How does redox regulation of APSK2 affect enzyme activity? | Point mutations in cysteine residues; redox assays |
| Can wild-type APS kinase rescue brachymorphic phenotype? | Knock-in of wild-type PAPSS2 in mutant mice |
| Where is APS kinase localized in cells? | Tagged knock-in with fluorescent protein |
| What is the effect of APS kinase overexpression on PAPS levels? | Overexpression cell lines; metabolomics |
| How do disease-associated mutations affect catalysis? | Point mutations in APS kinase domain; kinetic assays |
How to Study the adenylylsulfate kinase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Coupled enzyme assay | ADP or PAPS formation | Kinetic characterization of purified enzyme |
| Radioactive kinase assay | Incorporation of 32P into PAPS | Enzyme activity in tissue extracts |
| X-ray crystallography | Three-dimensional structure | Substrate binding and catalytic mechanism |
| Site-directed mutagenesis | Effect of specific residues on activity | Identification of catalytic residues |
| CRISPR knockout | Loss of gene function | Phenotypic analysis in cells and mice |
| Metabolomics (LC-MS) | PAPS and APS levels | Quantification of pathway flux |
| Redox titration | Enzyme activity under varying redox conditions | Study of redox regulation |
| Recombinant expression | Production of wild-type and mutant enzymes | Biochemical and structural studies |
Enzymatic activity assays
Adenylylsulfate kinase activity can be measured using coupled enzyme assays that monitor the formation of ADP or PAPS. Radioactive or fluorescent substrates are often used. Purified enzyme preparations from liver or recombinant sources are standard. These assays are essential for kinetic characterization and inhibitor testing.
Structural biology
X-ray crystallography and cryo-EM have been used to determine the structure of APS kinase from Archaeoglobus fulgidus and human PAPS synthase 2. These studies reveal substrate binding sites, catalytic residues, and conformational changes. Structural data guide mutational analysis and drug design.
Genetic and CRISPR models
CRISPR/Cas9 genome editing enables the creation of knockout, point-mutation, and knock-in models to study adenylylsulfate kinase function in vivo. Brachymorphic mice and patient-derived cells with PAPSS2 mutations are valuable models. These models help link enzyme activity to physiological outcomes.
Metabolomics and flux analysis
Mass spectrometry-based metabolomics can quantify PAPS and APS levels in cells and tissues, providing a readout of adenylylsulfate kinase activity. Stable isotope tracing can measure flux through the sulfate activation pathway. These methods are powerful for studying metabolic regulation.
How CRISPR Can Be Used to Study GO:0004020 adenylylsulfate kinase activity
Knockout
CRISPR/Cas9-mediated knockout of PAPSS1 or PAPSS2 eliminates adenylylsulfate kinase activity, leading to reduced PAPS levels and impaired sulfation. Knockout cell lines and mouse models are used to study the consequences of loss of function, such as skeletal defects and metabolic changes. These models are essential for validating the role of the enzyme in specific pathways.
Point Mutation
Point mutations can be introduced into the APS kinase domain to mimic disease-associated mutations or to probe catalytic residues. For example, mutations in the redox-sensitive cysteines of PAPSS2 APSK2 alter enzyme regulation. Such models help dissect the molecular basis of disease and enzyme mechanism.
Knock-in
Knock-in of wild-type or tagged versions of PAPSS2 allows rescue experiments and localization studies. Tagged knock-in (e.g., GFP or FLAG) enables visualization of the enzyme in live cells and tissues. Knock-in of human disease mutations into mouse models recapitulates human phenotypes.
Overexpression
Overexpression of PAPSS1 or PAPSS2 in cell lines increases adenylylsulfate kinase activity and PAPS production, which can enhance sulfation of substrates. This approach is used to study the effects of increased sulfate activation on cellular processes and to produce PAPS for in vitro assays.
How EDITGENE Supports adenylylsulfate kinase activity Research
Researchers studying adenylylsulfate kinase activity-related genes often need to determine whether a candidate gene is causally involved in sulfation-related phenotypes, metabolic disorders, or skeletal development. EDITGENE provides comprehensive CRISPR-based services to create precise cellular and animal models, enabling functional validation and mechanistic studies.
Contact EDITGENE today to design your custom CRISPR model for adenylylsulfate kinase activity research.
Frequently Asked Questions About adenylylsulfate kinase activity
What is adenylylsulfate kinase activity?
Adenylylsulfate kinase activity (GO:0004020) is the enzyme activity that catalyzes the phosphorylation of adenosine 5'-phosphosulfate (APS) to 3'-phosphoadenylyl sulfate (PAPS), using ATP as a phosphate donor.
What genes are involved in adenylylsulfate kinase activity?
The main genes are PAPSS1 and PAPSS2, which encode bifunctional enzymes with ATP-sulfurylase and APS kinase domains. In bacteria and archaea, separate APS kinase genes exist.
What is the reaction catalyzed by adenylylsulfate kinase?
The reaction is: adenosine 5'-phosphosulfate + ATP = 3'-phosphoadenylyl sulfate + ADP + H+.
Why is adenylylsulfate kinase important for health?
It produces PAPS, the universal sulfate donor required for sulfation of hormones, drugs, and glycosaminoglycans. Defects cause skeletal dysplasia and metabolic issues.
What diseases are associated with adenylylsulfate kinase mutations?
Mutations in PAPSS2 cause spondyloepimetaphyseal dysplasia and brachymorphic phenotype in mice. Impaired PAPS synthesis affects skeletal development.
How is adenylylsulfate kinase activity regulated?
In human PAPSS2, the APS kinase domain is regulated by redox state via a disulfide switch. Expression is tissue-specific and developmentally controlled.
What are the research methods to study adenylylsulfate kinase?
Common methods include enzymatic assays, X-ray crystallography, CRISPR knockout/knock-in models, and metabolomics to measure PAPS levels.
Can CRISPR be used to study adenylylsulfate kinase?
Yes, CRISPR knockout, point mutation, and knock-in models are widely used to study the function of PAPSS1/2 and their role in sulfation.
What is the structure of adenylylsulfate kinase?
The enzyme has a P-loop ATP-binding motif and a flexible lid. Crystal structures from Archaeoglobus fulgidus and human PAPSS2 reveal dimeric organization.
Where is adenylylsulfate kinase located in the cell?
It is a cytosolic enzyme. In higher eukaryotes, it is part of bifunctional PAPS synthase, which is also cytosolic.
Conclusion
Adenylylsulfate kinase activity (GO:0004020) is a critical molecular function in sulfur metabolism, responsible for producing PAPS, the universal sulfate donor. Its role in skeletal development, detoxification, and hormone regulation makes it a key research target. Defects in this activity lead to skeletal dysplasia and metabolic disorders, as demonstrated in animal models and human patients. Advances in structural biology and CRISPR genome editing continue to unravel its mechanism and regulation, offering potential for therapeutic intervention. Researchers can leverage EDITGENE's services to create precise models and accelerate discoveries in this field.
References
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- 4. Kawakami T et al.. 2023. Crystal structure of adenosine 5'-phosphosulfate kinase isolated from Archaeoglobus fulgidus.. Biochem Biophys Res Commun 643:105-110 PMID: 36592583
- 5. Sugahara K et al.. 1979. Defect in 3'-phosphoadenosine 5'-phosphosulfate formation in brachymorphic mice.. Proc Natl Acad Sci U S A 76(12):6615-8 PMID: 230515
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- 7. Zhang L et al.. 2023. Redox switching mechanism of the adenosine 5'-phosphosulfate kinase domain (APSK2) of human PAPS synthase 2.. Structure 31(7):826-835.e3 PMID: 37207644
- 8. Deyrup AT et al.. 1999. Activity and stability of recombinant bifunctional rearranged and monofunctional domains of ATP-sulfurylase and adenosine 5'-phosphosulfate kinase.. J Biol Chem 274(16):10751-7 PMID: 10196147
