GO:0047352 adenylylsulfate-ammonia adenylyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047352 describes the enzymatic activity that converts 5'-adenylyl sulfate (APS) and ammonia into adenosine 5'-phosphoramidate (AMP-NH2), sulfate, and protons.
• The reaction is a direct amidation of the sulfated adenosine nucleotide, producing a phosphoramidate bond that is chemically distinct from the phosphoanhydride bonds in ATP.
• The enzyme was first purified and characterized from the green alga Chlorella, where it participates in sulfur and nitrogen metabolism.
• Fhit proteins, known tumor suppressors, also possess this adenylylsulfate-ammonia adenylyltransferase activity, linking the GO term to cancer biology.
• The activity can be measured in vitro by monitoring AMP-NH2 formation from APS and ammonia, providing a direct biochemical assay for enzyme function.
• Studying GO:0047352 helps clarify how cells handle reactive sulfur and nitrogen species and may reveal new roles for Fhit in tumor suppression.
Description
Adenylylsulfate-ammonia adenylyltransferase activity, encoded by the Gene Ontology term GO:0047352, catalyzes a unique biochemical reaction: the conversion of 5'-adenylyl sulfate (APS) and ammonia into adenosine 5'-phosphoramidate (AMP-NH2), sulfate, and two protons. This activity was first discovered and purified from the green alga Chlorella, where it was shown to form AMP-NH2 from APS and ammonia. The reaction is unusual because it creates a phosphoramidate bond, a high-energy linkage that is rare in primary metabolism and distinct from the more common phosphoanhydride bonds found in ATP. For researchers, GO:0047352 matters because it connects sulfur assimilation, nitrogen metabolism, and nucleotide chemistry in a single enzymatic step. More recently, the same activity was identified as an inherent property of Fhit proteins, a family of tumor suppressors that are frequently lost in human cancers. This finding expanded the biological relevance of GO:0047352 beyond microbial metabolism and into cancer research, suggesting that Fhit may exert some of its tumor-suppressive effects through this enzymatic activity. Understanding the mechanism, regulation, and cellular context of adenylylsulfate-ammonia adenylyltransferase activity is therefore important for both basic enzymology and translational cancer biology.
adenylylsulfate-ammonia adenylyltransferase activity At A Glance
| GO ID | GO:0047352 |
|---|---|
| GO term | adenylylsulfate-ammonia adenylyltransferase activity |
| Ontology | molecular_function |
| Synonym | adenylylsulfate:ammonia adenylyltransferase activity; adenylylsulphate-ammonia adenylyltransferase activity; APSAT |
| Major function | Catalyzes the formation of adenosine 5'-phosphoramidate from 5'-adenylyl sulfate and ammonia, releasing sulfate and protons. |
| Reaction | 5'-adenylyl sulfate + NH4 = adenosine 5'-phosphoramidate + 2 H+ + sulfate. |
| Substrates | 5'-adenylyl sulfate (APS) and ammonia (NH4). |
| Products | Adenosine 5'-phosphoramidate, sulfate, and two protons. |
| Known sources | Purified from Chlorella; activity also found in Fhit proteins. |
What Is GO:0047352?
GO:0047352 is defined as the catalysis of the reaction: 5'-adenylyl sulfate + NH4 = adenosine 5'-phosphoramidate + 2 H+ + sulfate. In simpler terms, the enzyme takes a sulfated adenosine nucleotide (APS) and ammonia, and joins the ammonia to the adenosine 5'-phosphate group while releasing sulfate and protons. The product, adenosine 5'-phosphoramidate, contains a phosphoramidate bond (P-N) instead of the typical phosphoanhydride bond (P-O-P) found in ATP. This activity is classified as a molecular_function in the Gene Ontology and is also known by the synonym APSAT.
Why Is adenylylsulfate-ammonia adenylyltransferase activity Important in Cell Biology?
GO:0047352 is important because it represents a rare enzymatic route to phosphoramidate bonds, which are chemically distinct from the phosphoanhydride bonds that power most cellular processes. The activity was first characterized in Chlorella, where it likely contributes to sulfur and nitrogen handling, but its discovery in Fhit proteins has linked it to tumor suppression in humans. Fhit is frequently inactivated in many cancers, and its ability to catalyze this reaction suggests that AMP-NH2 production or APS detoxification may be part of its tumor-suppressive function. Thus, studying GO:0047352 can provide new insights into cancer biology, microbial metabolism, and the broader chemistry of nucleotide derivatives.
• Provides a direct enzymatic route to adenosine 5'-phosphoramidate, a rare phosphoramidate-containing nucleotide.
• Links sulfur metabolism (via APS) to nitrogen metabolism (via ammonia) in a single step.
• The enzyme was first purified from Chlorella, establishing a model for studying algal sulfur/nitrogen interactions.
• Fhit proteins possess this activity, connecting GO:0047352 to tumor suppressor biology.
• Loss of Fhit is common in many human cancers, making this activity a potential biomarker or therapeutic target.
• The reaction produces protons, which may influence local pH and cellular signaling.
• Assays for this activity can be used to screen for inhibitors or activators of Fhit or related enzymes.
• Understanding the mechanism may inspire synthetic biology approaches to produce phosphoramidate compounds.
• The activity may help detoxify APS, a reactive intermediate in sulfur metabolism.
• Studying GO:0047352 in different organisms can reveal evolutionary conservation of nucleotide amidation pathways.
Molecular Mechanism of adenylylsulfate-ammonia adenylyltransferase activity
Substrate Binding and Recognition
In simple terms: The enzyme grabs APS and ammonia and holds them in place.
The enzyme binds 5'-adenylyl sulfate (APS) and ammonia (NH4) as substrates. APS is a sulfated adenosine nucleotide, and its recognition likely involves interactions with the adenine ring and the 5'-phosphate group. Ammonia is a small nucleophile that must be positioned near the sulfur atom of APS for the reaction to occur. The binding of these substrates is the first step in the catalytic cycle, and it determines the specificity of the enzyme for APS over other nucleotides.
Catalytic Mechanism and Bond Formation
In simple terms: The enzyme swaps the sulfate group on APS with ammonia to make AMP-NH2.
The catalytic mechanism involves the nucleophilic attack of ammonia on the sulfur atom of APS, displacing sulfate and forming a phosphoramidate bond between the 5'-phosphate of adenosine and ammonia. This results in the product adenosine 5'-phosphoramidate (AMP-NH2), along with sulfate and two protons. The reaction is unusual because it creates a P-N bond, which is chemically distinct from the P-O-P bonds in ATP. The enzyme likely uses general acid-base catalysis or metal ions to stabilize the transition state, although the exact residues involved have not been fully characterized.
Product Release and Proton Balance
In simple terms: After making AMP-NH2, the enzyme releases it along with sulfate and protons.
Following catalysis, the enzyme releases adenosine 5'-phosphoramidate, sulfate, and two protons. The release of protons may affect local pH and could be coupled to cellular buffering systems. The product AMP-NH2 is a stable metabolite that can be further metabolized or excreted, depending on the organism. In Chlorella, the enzyme was purified and shown to catalyze this reaction, confirming the product identity.
Fhit Proteins as Catalysts
In simple terms: Fhit proteins can also perform this reaction, linking it to cancer.
Fhit proteins, which are known tumor suppressors, possess adenylylsulfate-ammonia adenylyltransferase activity as an inherent property. This means that Fhit can catalyze the same reaction as the Chlorella enzyme, converting APS and ammonia to AMP-NH2. The discovery that Fhit has this activity suggests that some of its tumor-suppressive functions may be mediated through this enzymatic reaction. However, the exact role of this activity in Fhit's tumor suppression remains an active area of research.
Regulation and Cofactors
In simple terms: The enzyme may need specific conditions or cofactors to work.
The activity of adenylylsulfate-ammonia adenylyltransferase may depend on the availability of APS and ammonia, as well as the presence of specific cofactors or metal ions. In Chlorella, the enzyme was purified and characterized, but detailed regulatory mechanisms have not been fully elucidated. For Fhit, the enzymatic activity may be regulated by protein-protein interactions or post-translational modifications, but this is not yet well understood. Further studies are needed to identify any allosteric regulators or inhibitors.
Key Genes Involved in GO:0047352 adenylylsulfate-ammonia adenylyltransferase activity
The following genes and proteins are directly or indirectly associated with adenylylsulfate-ammonia adenylyltransferase activity (GO:0047352), based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| FHIT | Human tumor suppressor with adenylylsulfate-ammonia adenylyltransferase activity | Frequently lost in cancers; potential therapeutic target |
| Chlorella APSAT | Purified enzyme from Chlorella that catalyzes the reaction | Model for studying algal sulfur/nitrogen metabolism |
| APS | Substrate for the enzyme; 5'-adenylyl sulfate | Central metabolite in sulfur assimilation |
| NH4 | Substrate; ammonia | Nitrogen source for the reaction |
| AMP-NH2 | Product; adenosine 5'-phosphoramidate | Rare phosphoramidate nucleotide |
| Fhit (other species) | Homologs of Fhit may also possess this activity | Comparative enzymology |
| ATP | Not a substrate but related nucleotide | Used as a control in enzyme assays |
| APS kinase | Competes for APS in sulfur metabolism | Potential cross-talk with APSAT |
| Sulfate | Product of the reaction | Can be measured to monitor activity |
| Proton | Product; two H+ released | May affect local pH |
| Fhit interacting proteins | May regulate Fhit activity | Potential modulators of APSAT activity |
| Chlorella proteins | Other enzymes in sulfur/nitrogen pathways | Context for APSAT function |
| Fhit mutants | Variants used to study activity | Structure-function studies |
| APSAT inhibitors | Not yet identified | Potential drug discovery targets |
| Ammonia transporters | Supply NH4 for the reaction | Indirect regulators |
| Sulfate transporters | Supply sulfate for APS synthesis | Indirect regulators |
| Fhit knockout models | Used to study loss of activity | Cancer research |
How Is adenylylsulfate-ammonia adenylyltransferase activity Regulated?
The regulation of adenylylsulfate-ammonia adenylyltransferase activity is not well characterized. In Chlorella, the enzyme was purified and its basic properties were studied, but no specific allosteric regulators or post-translational modifications have been reported. For Fhit, the enzymatic activity may be influenced by protein-protein interactions or cellular localization, but these mechanisms remain largely unexplored. The availability of substrates APS and ammonia likely plays a major role in controlling the reaction rate in vivo. Further research is needed to identify any regulatory pathways, such as those involving sulfur or nitrogen sensing, that might modulate this activity.
adenylylsulfate-ammonia adenylyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| FHIT | Cancer (lung, gastric, kidney) | Fhit knockout cell lines and mouse models |
| FHIT | Tumor suppression | Overexpression of wild-type vs. mutant Fhit |
| Chlorella APSAT | Algal sulfur/nitrogen metabolism | Chlorella cultures with altered APSAT expression |
| APSAT (general) | Metabolic disorders of sulfur/nitrogen | Enzyme assays in patient samples |
| FHIT | Oxidative stress response | Fhit-deficient cells treated with oxidants |
Fhit Loss and Cancer
Fhit proteins, which possess adenylylsulfate-ammonia adenylyltransferase activity, are frequently inactivated in many human cancers, including lung, gastric, and kidney cancers. The loss of Fhit expression is often associated with tumor progression and poor prognosis. The discovery that Fhit has this enzymatic activity suggests that its tumor-suppressive function may be linked to its ability to convert APS and ammonia to AMP-NH2. However, the exact contribution of this activity to cancer suppression is not yet fully understood.
Potential Role in Sulfur and Nitrogen Metabolism Disorders
Because the enzyme uses APS and ammonia, it may be involved in disorders of sulfur or nitrogen metabolism. In Chlorella, the enzyme was shown to form AMP-NH2 from APS and ammonia, indicating a role in handling these metabolites. In humans, defects in sulfur metabolism can lead to conditions such as sulfite oxidase deficiency, but a direct link to this enzyme has not been established. Further research is needed to determine if altered APSAT activity contributes to any metabolic diseases.
Neurodegeneration and Oxidative Stress
Fhit is known to be involved in the DNA damage response and oxidative stress pathways. The adenylylsulfate-ammonia adenylyltransferase activity of Fhit might influence cellular redox balance by affecting sulfur metabolism. However, no direct evidence links this activity to neurodegeneration, and any connection remains speculative.
From adenylylsulfate-ammonia adenylyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does Fhit's APSAT activity contribute to tumor suppression? | Fhit knockout and point-mutant knock-in cell lines |
| What is the catalytic mechanism of APSAT? | Purified recombinant enzyme and site-directed mutagenesis |
| How does APSAT affect sulfur metabolism? | Chlorella or human cell lines with altered APSAT expression |
| Can APSAT activity be modulated by small molecules? | High-throughput enzyme assays with compound libraries |
| What are the substrates and products in vivo? | Metabolomics of cells expressing APSAT |
| Is APSAT activity conserved across species? | Comparative enzymology using Fhit homologs |
How to Study the adenylylsulfate-ammonia adenylyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| HPLC-based enzyme assay | Formation of AMP-NH2 from APS and ammonia | Kinetic characterization of APSAT |
| Mass spectrometry | Identification and quantification of AMP-NH2 | Product confirmation in cell lysates |
| CRISPR-Cas9 knockout | Loss of APSAT gene function | Studying cellular roles of Fhit |
| RNA interference | Knockdown of APSAT expression | Transient loss-of-function studies |
| Metabolomics | Changes in APS, AMP-NH2, sulfate, ammonia | Pathway analysis |
| Site-directed mutagenesis | Effect of specific residues on activity | Mechanistic studies |
| X-ray crystallography | Three-dimensional structure of APSAT | Structure-function analysis |
| Western blot | Protein expression levels of Fhit | Validation of knockout or overexpression |
Enzymatic Assays for APSAT Activity
The most direct way to study adenylylsulfate-ammonia adenylyltransferase activity is to measure the formation of adenosine 5'-phosphoramidate from APS and ammonia. This can be done using purified enzyme or cell lysates, followed by separation and detection of AMP-NH2 by HPLC or mass spectrometry. The release of sulfate or protons can also be monitored spectrophotometrically. These assays are essential for characterizing enzyme kinetics, substrate specificity, and inhibitor effects.
Genetic Knockout and Knockdown
To study the cellular role of APSAT, researchers can use CRISPR-Cas9 to knock out the gene encoding the enzyme (e.g., FHIT in human cells) or RNA interference to reduce its expression. These models allow assessment of how loss of activity affects cell growth, stress responses, and tumorigenicity. In Chlorella, similar approaches could be used to study the algal enzyme's function.
Metabolomics and Flux Analysis
Metabolomic profiling can reveal changes in APS, AMP-NH2, sulfate, and ammonia levels in cells with altered APSAT activity. Stable isotope tracing can be used to follow the flux of sulfur and nitrogen through the pathway. These methods help place APSAT within the broader metabolic network.
Structural Biology and Mutagenesis
Determining the three-dimensional structure of APSAT or its Fhit homolog would provide insights into the catalytic mechanism. Site-directed mutagenesis of predicted active-site residues can test their roles in catalysis. Such studies are crucial for understanding how the enzyme achieves phosphoramidate bond formation.
How CRISPR Can Be Used to Study GO:0047352 adenylylsulfate-ammonia adenylyltransferase activity
Knockout
CRISPR-Cas9 knockout of FHIT or the Chlorella APSAT gene can completely abolish adenylylsulfate-ammonia adenylyltransferase activity. These knockout models are valuable for studying the consequences of losing this activity on cell growth, metabolism, and tumor suppression. In cancer research, Fhit knockout cells can be used to test whether reintroducing wild-type or catalytically dead Fhit restores normal phenotypes.
Point Mutation
Point mutations can be introduced into the active site of APSAT or Fhit to dissect the catalytic mechanism. For example, mutating residues predicted to bind APS or ammonia can reveal their importance for activity. Such mutants can be expressed in cells to test whether the enzymatic activity is required for Fhit's tumor-suppressive function.
Knock-in
Knock-in of a tagged version of APSAT or Fhit (e.g., FLAG or GFP) allows for affinity purification and localization studies. This can help identify interacting proteins and determine where the enzyme acts within the cell. Knock-in of disease-associated variants can also model human mutations.
Overexpression
Overexpression of APSAT or Fhit in cell lines can increase the production of AMP-NH2 and alter sulfur/nitrogen metabolism. This approach is useful for studying the downstream effects of elevated enzyme activity and for producing enough protein for biochemical assays. Overexpression models can also be used to test inhibitors.
How EDITGENE Supports adenylylsulfate-ammonia adenylyltransferase activity Research
Researchers studying adenylylsulfate-ammonia adenylyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in a specific metabolic or disease phenotype. EDITGENE provides a comprehensive suite of CRISPR-based services to enable such functional studies, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for adenylylsulfate-ammonia adenylyltransferase activity research.
Frequently Asked Questions About adenylylsulfate-ammonia adenylyltransferase activity
What is adenylylsulfate-ammonia adenylyltransferase activity?
It is an enzymatic activity, defined by GO:0047352, that converts 5'-adenylyl sulfate and ammonia into adenosine 5'-phosphoramidate, sulfate, and protons.
What genes are involved in adenylylsulfate-ammonia adenylyltransferase activity?
The FHIT gene in humans encodes a protein with this activity, and the enzyme has also been purified from Chlorella.
What is the reaction catalyzed by GO:0047352?
The reaction is: 5'-adenylyl sulfate + NH4 = adenosine 5'-phosphoramidate + 2 H+ + sulfate.
What is adenosine 5'-phosphoramidate?
It is the product of the reaction, a nucleotide with a phosphoramidate bond between the 5'-phosphate and ammonia.
How is adenylylsulfate-ammonia adenylyltransferase activity measured?
It can be measured by incubating APS and ammonia with the enzyme and detecting AMP-NH2 formation using HPLC or mass spectrometry.
Is adenylylsulfate-ammonia adenylyltransferase activity related to cancer?
Yes, Fhit proteins, which are tumor suppressors, possess this activity, and loss of Fhit is common in many cancers.
What is the role of Fhit in cancer?
Fhit is a tumor suppressor that is frequently inactivated in cancers; its adenylylsulfate-ammonia adenylyltransferase activity may contribute to its tumor-suppressive function.
Can I study this activity using CRISPR?
Yes, CRISPR-Cas9 can be used to knock out or mutate genes encoding this activity, such as FHIT, to study its cellular roles.
What model organisms are used to study GO:0047352?
Chlorella is a model for the algal enzyme, and human cell lines are used to study Fhit.
What are the synonyms for adenylylsulfate-ammonia adenylyltransferase activity?
Synonyms include adenylylsulfate:ammonia adenylyltransferase activity, adenylylsulphate-ammonia adenylyltransferase activity, and APSAT.
Conclusion
Adenylylsulfate-ammonia adenylyltransferase activity (GO:0047352) is a unique enzymatic function that produces the rare phosphoramidate nucleotide AMP-NH2 from APS and ammonia. Its discovery in Fhit proteins has linked this activity to tumor suppression, opening new avenues for cancer research. Understanding the mechanism, regulation, and cellular roles of this activity requires a combination of biochemical assays, genetic models, and advanced CRISPR technologies. EDITGENE offers a full range of services to support such research, from knockout and knock-in models to library screening and bioinformatics.
References
- 1. Wojdyła-Mamoń AM et al.. 2015. Adenylylsulfate-ammonia adenylyltransferase activity is another inherent property of Fhit proteins.. Biosci Rep 35(4) PMID: 26181368
- 2. Fankhauser H et al.. 1981. Purification and properties of adenylyl sulphate:ammonia adenylyltransferase from Chlorella catalysing the formation of adenosine 5' -phosphoramidate from adenosine 5' -phosphosulphate and ammonia.. Biochem J 195(3):545-60 PMID: 6274307
