GO:0047800 cysteamine dioxygenase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047800 cysteamine dioxygenase activity catalyzes the reaction cysteamine + O2 = H+ + hypotaurine, as defined by QuickGO.
• Cysteamine dioxygenase (ADO) is the second mammalian thiol dioxygenase discovered, distinct from cysteine dioxygenase.
• ADO functions as an oxygen sensor and regulates the Cys-N-degron pathway by oxidizing N-terminal cysteine residues of protein substrates.
• The enzyme uses a non-heme mononuclear iron center; cobalt-substituted ADO proceeds through a cobalt(III)-superoxo intermediate.
• Hydralazine inhibits cysteamine dioxygenase and has therapeutic potential in preeclampsia and glioblastoma.
• In fish, ADO is involved in the Arg/N-degron pathway and host response to rhabdovirus infection.
Description
Cysteamine dioxygenase activity (GO:0047800) is a molecular function defined by the catalysis of the reaction cysteamine + O2 = H+ + hypotaurine. This enzymatic activity is carried out by cysteamine dioxygenase (ADO), a non-heme iron-dependent thiol dioxygenase that was discovered as the second mammalian thiol dioxygenase after cysteine dioxygenase. ADO is widely conserved and plays critical roles in sulfur metabolism and oxygen sensing. The enzyme is also known as persulfurase and 2-aminoethanethiol:oxygen oxidoreductase, reflecting its substrate specificity and catalytic mechanism. Researchers study GO:0047800 because of its emerging roles in the Cys-N-degron pathway, pexophagy, and diseases such as preeclampsia and glioblastoma. The activity is essential for regulating protein stability through N-terminal oxidation, linking oxygen availability to cellular proteostasis. Recent structural and spectroscopic studies have elucidated the catalytic cycle, including the formation of a cobalt(III)-superoxo intermediate in metal-substituted enzymes. These findings position cysteamine dioxygenase as a key node in oxygen sensing and a potential therapeutic target.
cysteamine dioxygenase activity At A Glance
| GO ID | GO:0047800 |
|---|---|
| GO term | cysteamine dioxygenase activity |
| Ontology | molecular_function |
| Synonym | 2-aminoethanethiol:oxygen oxidoreductase activity; cysteamine oxygenase activity; cysteamine:oxygen oxidoreductase activity; persulfurase activity |
| Major function | Catalyzes the oxidation of cysteamine to hypotaurine using molecular oxygen |
| Reaction | cysteamine + O2 = H+ + hypotaurine |
| Cofactor | Non-heme mononuclear iron (Fe2+) |
| Substrate specificity | Cysteamine and other thiol-containing compounds |
| Major enzyme | Cysteamine dioxygenase (ADO) |
What Is GO:0047800?
According to QuickGO, GO:0047800 cysteamine dioxygenase activity is defined as the catalysis of the reaction: cysteamine + O2 = H+ + hypotaurine. In other words, it is an oxidoreductase activity that uses molecular oxygen to oxidize cysteamine, producing hypotaurine and a proton. This activity is synonymous with 2-aminoethanethiol:oxygen oxidoreductase activity, cysteamine oxygenase activity, cysteamine:oxygen oxidoreductase activity, and persulfurase activity. The enzyme responsible, cysteamine dioxygenase (ADO), is a non-heme iron-dependent dioxygenase that specifically acts on thiol-containing substrates.
Why Is cysteamine dioxygenase activity Important in Cell Biology?
Cysteamine dioxygenase activity is important because it links oxygen availability to protein stability through the Cys-N-degron pathway, a process that regulates pexophagy and cellular responses to hypoxia. The enzyme is also involved in sulfur amino acid metabolism, producing hypotaurine, a precursor of taurine. Dysregulation of ADO has been implicated in preeclampsia and glioblastoma, where hydralazine, an ADO inhibitor, shows therapeutic efficacy. In fish, ADO is involved in the Arg/N-degron pathway and host defense against rhabdovirus infection. Thus, understanding GO:0047800 provides insights into oxygen sensing, proteostasis, and disease mechanisms.
• Regulates the Cys-N-degron pathway by oxidizing N-terminal cysteine residues of target proteins.
• Modulates pexophagy through N-terminal oxidation and arginylation of ACAD10.
• Acts as an oxygen sensor, linking oxygen levels to protein degradation.
• Involved in sulfur metabolism and hypotaurine production.
• Inhibited by hydralazine, with therapeutic implications for preeclampsia and glioblastoma.
• Plays a role in host response to rhabdovirus infection in fish.
• Provides a model for studying non-heme iron dioxygenases and metal-substitution effects.
• Potential target for modulating protein stability in disease.
Molecular Mechanism of cysteamine dioxygenase activity
Substrate Binding and Iron Center
In simple terms: The enzyme uses an iron atom to grab cysteamine and oxygen.
Cysteamine dioxygenase (ADO) is a non-heme mononuclear iron enzyme that binds cysteamine and molecular oxygen at its active site. Spectroscopic studies have confirmed the ferrous iron center and its role in substrate coordination. The enzyme specifically recognizes the thiol group of cysteamine, positioning it for oxidation.
Catalytic Cycle and Superoxo Intermediate
In simple terms: Oxygen attaches to the iron, forming a reactive intermediate that oxidizes cysteamine.
The catalytic cycle involves the activation of molecular oxygen to form an iron-superoxo intermediate. In cobalt-substituted ADO, a cobalt(III)-superoxo complex is observed, which then attacks the substrate. This intermediate is crucial for the oxidation of cysteamine to hypotaurine. The reaction proceeds through a mechanism involving hydrogen atom abstraction and subsequent oxygen insertion.
Product Formation and Release
In simple terms: The oxidized product, hypotaurine, is released along with a proton.
Following oxidation, hypotaurine is released as the product, along with a proton. The enzyme returns to its resting state, ready for another catalytic cycle. The reaction is stereospecific and produces hypotaurine, a key metabolite in taurine biosynthesis.
Metal Substitution and Mechanistic Insights
In simple terms: Replacing iron with cobalt helps researchers understand how the enzyme works.
Metal-substitution approaches, such as replacing iron with cobalt, have provided insights into the catalytic mechanism. Cobalt-substituted ADO retains activity and forms a cobalt(III)-superoxo intermediate, which has been characterized by spectroscopic methods. These studies help dissect the roles of the metal center in oxygen activation and substrate oxidation.
Regulation by Oxygen Availability
In simple terms: The enzyme's activity depends on how much oxygen is around, making it an oxygen sensor.
ADO activity is regulated by oxygen availability, as it requires O2 as a substrate. Under hypoxia, ADO activity is reduced, leading to decreased oxidation of N-terminal cysteine residues in target proteins. This oxygen-sensing function links cellular metabolism to protein stability via the Cys-N-degron pathway.
Key Genes Involved in GO:0047800 cysteamine dioxygenase activity
The following genes and proteins are directly involved in or regulated by cysteamine dioxygenase activity (GO:0047800).
| Gene | Major Role | Research Relevance |
|---|---|---|
| ADO | Encodes cysteamine dioxygenase, the enzyme catalyzing GO:0047800 | Central to studies of thiol dioxygenases and oxygen sensing |
| CDO1 | Cysteine dioxygenase, a related thiol dioxygenase | Comparative studies with ADO to understand substrate specificity |
| ACAD10 | Substrate of Cys-N-degron pathway, regulated by ADO-mediated oxidation | Links ADO activity to pexophagy and metabolic regulation |
| ATE1 | Arginyl-tRNA-protein transferase, involved in N-degron pathway | Works with ADO in the Cys-N-degron pathway |
| NTAQ1 | N-terminal glutamine amidohydrolase, part of N-degron pathway | May interact with ADO pathway components |
| UBR1 | E3 ubiquitin ligase recognizing N-degrons | Mediates degradation of ADO-oxidized proteins |
| UBR2 | E3 ubiquitin ligase recognizing N-degrons | Potential role in degrading oxidized substrates |
| UBR4 | E3 ubiquitin ligase recognizing N-degrons | May recognize N-terminal cysteine oxidation products |
| UBR5 | E3 ubiquitin ligase recognizing N-degrons | Involved in N-degron pathway |
| HIF1A | Hypoxia-inducible factor, indirectly linked to oxygen sensing | May be affected by ADO-mediated oxygen sensing |
| VHL | E3 ubiquitin ligase targeting HIF1A | Part of oxygen-sensing pathways |
| SINI | Siniperca chuatsi rhabdovirus protein, interacts with fish ADO | Studied in fish ADO and virus infection |
| ACAD10 | Acyl-CoA dehydrogenase 10, substrate of Cys-N-degron pathway | Regulated by ADO and arginylation |
| Cys | N-terminal cysteine residue on substrate proteins | Direct target of ADO oxidation |
| O2 | Molecular oxygen, substrate for ADO | Essential for catalytic activity |
| Hypotaurine | Product of ADO reaction | Metabolite in taurine biosynthesis |
| Cysteamine | Substrate of ADO | Used in assays to measure ADO activity |
How Is cysteamine dioxygenase activity Regulated?
Cysteamine dioxygenase activity is regulated at multiple levels. Its activity is directly dependent on oxygen availability, as O2 is a substrate, making it an oxygen sensor. The enzyme's expression may be regulated by hypoxia-inducible factors, although direct evidence is limited. Additionally, the Cys-N-degron pathway, in which ADO participates, is regulated by components such as ATE1 and UBR ligases. Hydralazine acts as an inhibitor of ADO, providing a pharmacological means to modulate its activity. In fish, ADO is involved in the Arg/N-degron pathway and may be regulated during viral infection.
cysteamine dioxygenase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ADO | Preeclampsia, glioblastoma | KO and overexpression in cell lines, xenograft models |
| ACAD10 | Pexophagy, metabolic regulation | Point mutation of N-terminal cysteine, KO cells |
| ADO | Rhabdovirus infection (fish) | Knockout in fish cell lines, viral challenge |
| ADO | Oxygen sensing and proteostasis | Hypoxia experiments, tagged knock-in for localization |
| ADO | Thiol dioxygenase mechanism | Metal-substitution, point mutations at iron-binding residues |
Preeclampsia and Glioblastoma
Hydralazine, an inhibitor of cysteamine dioxygenase, has been shown to treat preeclampsia and induce senescence in glioblastoma. This suggests that ADO activity contributes to the pathophysiology of these conditions, and its inhibition may be therapeutically beneficial.
Pexophagy and Metabolic Regulation
The Cys-N-degron pathway, modulated by ADO through N-terminal oxidation of ACAD10, regulates pexophagy. Dysregulation of this pathway may contribute to metabolic disorders and neurodegeneration.
Viral Infection
In Mandarin fish, cysteamine dioxygenase is involved in the Arg/N-degron pathway and plays a role in Siniperca chuatsi rhabdovirus infection. This highlights a potential role for ADO in host-pathogen interactions.
From cysteamine dioxygenase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of ADO loss on pexophagy? | ADO knockout cells |
| How does N-terminal cysteine oxidation regulate ACAD10? | Point mutation of ACAD10 N-terminal cysteine |
| Can ADO be targeted for glioblastoma therapy? | ADO overexpression and hydralazine treatment in glioblastoma cells |
| What is the role of ADO in oxygen sensing? | Tagged knock-in of ADO for live-cell imaging under hypoxia |
| How does ADO recognize substrates? | Knock-in of substrate proteins with tagged N-termini |
| What is the catalytic mechanism of ADO? | Point mutations in iron-binding residues, metal substitution |
How to Study the cysteamine dioxygenase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| HPLC-MS assay | Conversion of cysteamine to hypotaurine | Measuring ADO activity and inhibition |
| UV-vis spectroscopy | Iron center oxidation states | Characterizing ADO and metal-substituted forms |
| EPR spectroscopy | Paramagnetic intermediates | Detecting superoxo species |
| Resonance Raman | Metal-oxygen vibrations | Identifying cobalt(III)-superoxo |
| Proteomics | N-terminal oxidation of proteins | Mapping Cys-N-degron substrates |
| Knockout cell lines | Loss of ADO function | Studying pexophagy and oxygen sensing |
| Hypoxia chamber | Oxygen-dependent ADO activity | Investigating oxygen sensing |
| Hydralazine treatment | Inhibition of ADO | Therapeutic studies in preeclampsia and glioblastoma |
Enzymatic Assays for ADO Activity
ADO activity can be measured using HPLC-MS assays that detect the conversion of cysteamine to hypotaurine. These assays are sensitive and can be used to screen inhibitors such as hydralazine. Metal-substitution approaches combined with spectroscopy provide mechanistic insights.
Spectroscopic Characterization
Spectroscopic methods, including UV-vis, EPR, and Mössbauer, have been used to characterize the iron center and reaction intermediates of ADO. Cobalt-substituted ADO allows the observation of superoxo intermediates by resonance Raman.
Proteomic and Degradomic Approaches
Proteomics can identify proteins with N-terminal cysteine oxidation by ADO, using enrichment of oxidized N-termini. This helps map the Cys-N-degron substrate repertoire.
Cell-Based Models and Imaging
Knockout and knock-in cell lines, combined with fluorescence microscopy, can visualize ADO localization and substrate oxidation. Hypoxia chambers are used to modulate oxygen levels.
How CRISPR Can Be Used to Study GO:0047800 cysteamine dioxygenase activity
Knockout
CRISPR knockout of ADO can be used to study its role in the Cys-N-degron pathway, pexophagy, and oxygen sensing. ADO knockout cells show altered stability of N-terminal cysteine substrates. In fish, ADO knockout can reveal its role in rhabdovirus infection.
Point Mutation
Point mutations in the iron-binding residues of ADO can dissect the catalytic mechanism. Mutating the N-terminal cysteine of substrate proteins like ACAD10 can prevent oxidation and block downstream arginylation.
Knock-in
Knock-in of tagged ADO (e.g., GFP or HA) allows live-cell imaging and localization studies. Knock-in of substrate proteins with tagged N-termini can facilitate proteomic identification of ADO targets.
Overexpression
Overexpression of ADO can enhance Cys-N-degron pathway activity and reduce substrate stability. In glioblastoma cells, ADO overexpression may sensitize to hydralazine.
How EDITGENE Supports cysteamine dioxygenase activity Research
Researchers studying cysteamine dioxygenase activity-related genes often need to determine whether a candidate gene is causally involved in oxygen sensing, pexophagy, or disease. EDITGENE provides CRISPR-based services to create precise cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for cysteamine dioxygenase activity research.
Frequently Asked Questions About cysteamine dioxygenase activity
What is cysteamine dioxygenase activity?
Cysteamine dioxygenase activity (GO:0047800) is the catalysis of the reaction cysteamine + O2 = H+ + hypotaurine, as defined by QuickGO.
What genes are involved in cysteamine dioxygenase activity?
The primary gene is ADO, encoding cysteamine dioxygenase. Related genes include CDO1, ACAD10, ATE1, and UBR ligases.
What is the function of cysteamine dioxygenase?
It oxidizes cysteamine to hypotaurine and regulates the Cys-N-degron pathway, acting as an oxygen sensor.
How is cysteamine dioxygenase regulated?
Its activity depends on oxygen availability and is inhibited by hydralazine.
What diseases are associated with cysteamine dioxygenase?
Preeclampsia, glioblastoma, and viral infections in fish have been linked to ADO activity.
What is the Cys-N-degron pathway?
A protein degradation pathway where N-terminal cysteine oxidation by ADO leads to arginylation and ubiquitination.
How can I measure cysteamine dioxygenase activity?
Using HPLC-MS assays that detect hypotaurine production from cysteamine.
What is the metal cofactor of cysteamine dioxygenase?
It is a non-heme mononuclear iron enzyme.
Can cysteamine dioxygenase be inhibited?
Yes, hydralazine inhibits ADO and has therapeutic effects in preeclampsia and glioblastoma.
What model systems are used to study cysteamine dioxygenase?
Knockout and knock-in cell lines, fish models, and metal-substituted enzymes are commonly used.
Conclusion
Cysteamine dioxygenase activity (GO:0047800) is a critical molecular function that links oxygen sensing to protein stability through the Cys-N-degron pathway. Its enzyme, ADO, is a non-heme iron dioxygenase with emerging roles in pexophagy, preeclampsia, and glioblastoma. Understanding its mechanism and regulation offers opportunities for therapeutic intervention. EDITGENE provides comprehensive CRISPR services to accelerate research on this important pathway.
References
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- 3. Li J et al.. 2024. Cobalt(II)-Substituted Cysteamine Dioxygenase Oxygenation Proceeds through a Cobalt(III)-Superoxo Complex.. J Am Chem Soc 146(27):18292-18297 PMID: 38941563
- 4. Shim SM et al.. 2023. The Cys-N-degron pathway modulates pexophagy through the N-terminal oxidation and arginylation of ACAD10.. Autophagy 19(6):1642-1661 PMID: 36184612
- 5. Duan R et al.. 2024. Unveiling the mechanism of cysteamine dioxygenase: A combined HPLC-MS assay and metal-substitution approach.. Methods Enzymol 703:147-166 PMID: 39260994
- 6. Dominy JE Jr et al.. 2007. Discovery and characterization of a second mammalian thiol dioxygenase, cysteamine dioxygenase.. J Biol Chem 282(35):25189-98 PMID: 17581819
- 7. Liu W et al.. 2023. Oxygen-Sensing Protein Cysteamine Dioxygenase from Mandarin Fish Involved in the Arg/N-Degron Pathway and Siniperca chuatsi Rhabdovirus Infection.. Viruses 15(8) PMID: 37631990
- 8. Patel K et al.. 2024. The enzymatic oxygen sensor cysteamine dioxygenase binds its protein substrates through their N-termini.. J Biol Chem 300(9):107653 PMID: 39122008
