GO:0004363 glutathione synthase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004363 (glutathione synthase activity) catalyzes the ATP-dependent ligation of L-gamma-glutamyl-L-cysteine and glycine to form glutathione (GSH), releasing ADP, phosphate, and two protons.
• Glutathione synthesis is a two-step process: the first, rate-limiting step is catalyzed by glutamate-cysteine ligase (GCL), and the second, final step is catalyzed by glutathione synthase (GSS).
• GSS is the only enzyme that performs the terminal step of glutathione biosynthesis, making it essential for maintaining cellular redox homeostasis.
• Deficiency or dysregulation of glutathione synthase activity is linked to oxidative stress, ferroptosis, and several human pathologies including neurodegeneration and metabolic disorders.
• Glutathione synthase activity can be regulated at the transcriptional level and by substrate availability, and its expression is induced under conditions of folate, vitamin E, and apolipoprotein E deficiency.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) are powerful tools to dissect the causal role of GSS and related genes in disease and to screen for modulators of glutathione synthase activity.
Description
Glutathione (GSH) is the most abundant non-protein thiol in mammalian cells and plays a central role in antioxidant defense, detoxification, and redox signaling. The final step in glutathione biosynthesis is catalyzed by glutathione synthase (GSS; EC 6.3.2.3), which ligates gamma-glutamylcysteine to glycine in an ATP-dependent manner. This enzymatic activity is annotated in the Gene Ontology as GO:0004363, glutathione synthase activity. Understanding this activity is fundamental for researchers studying oxidative stress, drug metabolism, and cellular responses to injury. Glutathione synthase activity is not only critical for maintaining intracellular GSH levels but also for regulating the balance between pro-oxidant and antioxidant environments. Dysregulation of GSH synthesis has been implicated in a wide range of diseases, including cancer, neurodegeneration, and metabolic disorders. Therefore, precise investigation of glutathione synthase activity and its regulatory network is essential for both basic biology and translational research.
glutathione synthase activity At A Glance
| GO ID | GO:0004363 |
|---|---|
| GO term | glutathione synthase activity |
| Ontology | molecular_function |
| Synonym | gamma-L-glutamyl-L-cysteine:glycine ligase (ADP-forming); glutathione synthetase activity; GSH synthetase activity |
| Definition | Catalysis of the reaction: L-gamma-glutamyl-L-cysteine + ATP + glycine = ADP + glutathione + 2 H+ + phosphate. |
| Major function | Final step of glutathione biosynthesis; ATP-dependent ligation of gamma-glutamylcysteine and glycine. |
| EC number | 6.3.2.3 |
| Cofactors | ATP, Mg2+ (or other divalent cations) |
| Substrates | L-gamma-glutamyl-L-cysteine, glycine, ATP |
| Products | Glutathione (GSH), ADP, phosphate, H+ |
What Is GO:0004363?
Glutathione synthase activity (GO:0004363) is defined as the catalysis of the reaction: L-gamma-glutamyl-L-cysteine + ATP + glycine = ADP + glutathione + 2 H+ + phosphate. In other words, it is the enzymatic activity that joins two amino acid precursors, gamma-glutamylcysteine and glycine, using the energy from ATP hydrolysis to form the tripeptide glutathione (GSH), releasing ADP, inorganic phosphate, and protons.
Why Is glutathione synthase activity Important in Cell Biology?
Glutathione synthase activity is indispensable for the production of glutathione, the principal intracellular antioxidant and redox buffer. Because GSH is involved in detoxification of reactive oxygen species, xenobiotics, and heavy metals, the enzyme that catalyzes its final synthesis step is a key node in cellular stress responses. Moreover, glutathione synthase activity influences diverse physiological processes such as cell proliferation, apoptosis, and immune function, and its impairment has been associated with oxidative stress-related diseases including neurodegeneration and ferroptosis. Thus, measuring and manipulating this activity is crucial for understanding disease mechanisms and for developing therapeutic strategies.
• Maintains cellular redox homeostasis by enabling glutathione synthesis.
• Protects against oxidative stress and ferroptosis in various cell types.
• Supports detoxification of xenobiotics and heavy metals.
• Plays a role in neuronal survival and function, with implications for neurodegenerative diseases.
• Is essential for efficient nodulation in certain bacteria, linking to symbiotic processes.
• Its expression is induced under nutritional deficiencies (folate, vitamin E, apolipoprotein E).
• Contributes to anti-glycation defenses in yeast.
• Serves as a potential therapeutic target for diseases characterized by glutathione depletion.
• Can be studied using CRISPR-based genetic models to establish causality.
• Its activity is a biomarker for oxidative stress and antioxidant capacity.
What Happens During glutathione synthase activity?
Substrate Binding and Activation
In simple terms: The enzyme grabs its two building blocks and an energy molecule to start the reaction.
Glutathione synthase binds its substrates L-gamma-glutamyl-L-cysteine and glycine, along with ATP, in a sequential ordered mechanism. The enzyme first binds gamma-glutamylcysteine and ATP, forming an acylphosphate intermediate, then glycine binds and the reaction proceeds.
Catalytic Ligation and Product Release
In simple terms: The enzyme links the two pieces together to make glutathione and releases the byproducts.
The gamma-carboxyl group of gamma-glutamylcysteine is activated by ATP to form a gamma-glutamyl phosphate intermediate, which is then attacked by the amino group of glycine, forming a peptide bond. This yields glutathione, ADP, and inorganic phosphate. The reaction also releases two protons.
Role in the Gamma-Glutamyl Cycle
In simple terms: This reaction is the last step in a cycle that recycles and produces glutathione.
Glutathione synthase activity is the final step of the gamma-glutamyl cycle, which also involves gamma-glutamyl transpeptidase, gamma-glutamyl cyclotransferase, and 5-oxoprolinase. This cycle is important for amino acid transport and glutathione turnover.
Tissue-Specific Expression and Isoforms
In simple terms: Different tissues may have different amounts of this enzyme.
Glutathione synthase is expressed in most tissues, with highest levels in liver, kidney, and erythrocytes. The enzyme is encoded by the GSS gene in humans. Alternative splicing may produce isoforms, but their functional significance is not fully understood.
Key Genes Involved in GO:0004363 glutathione synthase activity
The following genes and proteins are directly or indirectly involved in glutathione synthase activity and its regulation.
| Gene | Major Role | Research Relevance |
|---|---|---|
| GSS | Encodes glutathione synthase, the enzyme catalyzing the final step of GSH synthesis | Mutations cause glutathione synthetase deficiency; target for knockout/knock-in studies |
| GCLC | Encodes the catalytic subunit of glutamate-cysteine ligase, the rate-limiting enzyme in GSH synthesis | Regulates substrate supply for GSS; often co-studied |
| GCLM | Encodes the modifier subunit of glutamate-cysteine ligase, modulates GCL activity | Affects overall GSH synthesis capacity |
| GGT1 | Gamma-glutamyl transpeptidase, involved in GSH breakdown and recycling | Links GSS activity to the gamma-glutamyl cycle |
| GGCT | Gamma-glutamyl cyclotransferase, degrades gamma-glutamylcysteine | Competes with GSS for substrate |
| OPLAH | 5-oxoprolinase, part of the gamma-glutamyl cycle | Recycles 5-oxoproline to glutamate |
| Nrf2 (NFE2L2) | Transcription factor regulating antioxidant response genes including GSS | Modulates GSS expression under oxidative stress |
| KEAP1 | Negative regulator of Nrf2 | Mutations affect Nrf2-driven GSS expression |
| NF-κB | Transcription factor that can regulate GSS expression | Inflammatory signaling influences GSH synthesis |
| APOE | Apolipoprotein E, involved in lipid transport and antioxidant defense | Deficiency increases GSS transcription |
| MTHFR | Methylenetetrahydrofolate reductase, affects folate metabolism | Folate deficiency alters GSS expression |
| SLC7A11 | Cystine/glutamate antiporter, supplies cysteine for GSH synthesis | Regulates substrate availability for GCL and GSS |
| G6PD | Glucose-6-phosphate dehydrogenase, generates NADPH for GSH recycling | Supports redox balance |
| GPX4 | Glutathione peroxidase 4, uses GSH to detoxify lipid peroxides | Links GSH synthesis to ferroptosis prevention |
| P2X7R | Purine receptor involved in oxidative stress and ferroptosis | Modulates GSH levels via Akt/GSK3β/Nrf2 axis |
| LKB1/AMPK | Energy sensor pathway that can influence Nrf2 and GSH synthesis | Implicated in Friedreich ataxia models |
| GSK3β | Kinase that regulates Nrf2 stability | Affects GSS expression and GSH levels |
How Is glutathione synthase activity Regulated?
Glutathione synthase activity is regulated at multiple levels. Transcriptionally, the GSS gene is induced by oxidative stress via the Nrf2/ARE pathway, and its expression is increased in response to deficiencies in folate, vitamin E, and apolipoprotein E. The KEAP1/Nrf2 axis is a major regulator, with KEAP1 mutations leading to constitutive Nrf2 activation and elevated GSS expression. Additionally, the LKB1/AMPK pathway can modulate Nrf2 activity and thus influence GSH synthesis. Post-translationally, GSS activity may be affected by feedback inhibition by glutathione and by the availability of substrates gamma-glutamylcysteine and glycine. Hormonal and inflammatory signals, such as NF-κB, can also impact GSS expression.
glutathione synthase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| GSS | Glutathione synthetase deficiency; hemolytic anemia; neurological dysfunction | Knockout mice, patient-derived iPSCs, point-mutation knock-in |
| GSS | Cancer chemoresistance | Cancer cell lines with GSS overexpression or knockout |
| GSS | Ferroptosis in neurodegeneration | Neuronal cell models with GSS knockout or knockdown |
| NFE2L2 (Nrf2) | Oxidative stress-related diseases | Nrf2 knockout or constitutively active knock-in models |
| P2X7R | Diabetic neuropathy; ferroptosis | Satellite glial cell cultures with P2X7R modulation |
Glutathione Synthetase Deficiency
Mutations in the GSS gene cause glutathione synthetase deficiency, a rare autosomal recessive disorder characterized by hemolytic anemia, metabolic acidosis, and neurological symptoms. The deficiency leads to low glutathione levels, resulting in oxidative damage to red blood cells and neurons.
Neurodegeneration and Ferroptosis
Impaired glutathione synthesis contributes to ferroptosis, an iron-dependent form of cell death, in neurodegenerative conditions. In Friedreich ataxia models, dysregulation of the NRF2 response and GSH synthesis leads to ferroptosis in dorsal root ganglia. Similarly, in diabetic neuropathy models, high glucose-induced ferroptosis in satellite glial cells is linked to GSH depletion and can be alleviated by targeting P2X7R to activate the Akt/GSK3β/Nrf2 axis.
Cancer and Chemoresistance
Elevated glutathione synthase activity and GSH levels are often observed in cancer cells, contributing to resistance to chemotherapy and radiotherapy by detoxifying reactive oxygen species and drugs. Targeting GSH synthesis is a potential therapeutic strategy.
Metabolic and Nutritional Disorders
Nutritional deficiencies in folate, vitamin E, and apolipoprotein E can upregulate glutathione synthase transcription and activity as a compensatory mechanism, but chronic imbalance may lead to oxidative stress-related pathologies.
From glutathione synthase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of GSS cause glutathione depletion and oxidative stress? | GSS knockout cell lines or mice |
| Does a specific GSS mutation affect enzyme activity? | Point-mutation knock-in via CRISPR |
| Can tagged GSS be used to study localization and interactions? | Knock-in of FLAG/HA-tagged GSS |
| Does overexpression of GSS protect against ferroptosis? | GSS overexpression cell lines |
| What genes modulate glutathione synthase activity? | CRISPR library screening |
| How does GSS expression change under nutritional deficiency? | Wild-type and GSS reporter models |
How to Study the glutathione synthase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzymatic assay | Glutathione synthase activity | Kinetic studies, inhibitor screening |
| RNA-seq | GSS mRNA expression | Transcriptional regulation studies |
| Western blot | GSS protein levels | Protein expression analysis |
| Mass spectrometry | Glutathione and metabolites | Metabolic profiling |
| CRISPR knockout | Loss-of-function phenotypes | Causal gene identification |
| CRISPR activation | Gain-of-function phenotypes | Gene overexpression studies |
| Fluorescent biosensors | Intracellular GSH levels | Live-cell imaging of redox status |
Enzymatic Activity Assays
Glutathione synthase activity can be measured spectrophotometrically by coupling the reaction to the consumption of ATP or by detecting glutathione formation using Ellman's reagent. These assays are used to quantify enzyme kinetics and inhibitor effects.
Gene Expression Analysis
RNA-seq and qPCR can measure GSS mRNA levels under various conditions. Studies have shown increased GSS transcription in response to folate, vitamin E, and apolipoprotein E deficiencies.
Proteomics and Metabolomics
Mass spectrometry-based proteomics can quantify GSS protein levels, while metabolomics can measure glutathione and related metabolites to assess pathway flux.
CRISPR-Based Genetic Screens
Genome-wide CRISPR knockout or activation screens can identify genes that regulate glutathione synthase activity or glutathione levels, revealing novel modulators and potential drug targets.
How CRISPR Can Be Used to Study GO:0004363 glutathione synthase activity
Knockout
CRISPR knockout of GSS or related genes (e.g., GCLC, GCLM) can abolish glutathione synthase activity, leading to glutathione depletion and increased sensitivity to oxidative stress. These models are used to study the consequences of GSH deficiency and to validate drug targets.
Point Mutation
Introducing specific point mutations in GSS via CRISPR base editing or homology-directed repair can mimic human disease alleles, allowing researchers to study the impact on enzyme activity, stability, and cellular redox balance.
Knock-in
Knock-in of tagged GSS (e.g., FLAG, HA, or fluorescent protein) enables visualization, immunoprecipitation, and interaction studies. Knock-in of reporter genes under the GSS promoter can monitor expression dynamics.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of GSS can increase glutathione synthase activity and GSH levels, protecting cells from oxidative stress and ferroptosis. These models are useful for studying the protective effects of enhanced GSH synthesis.
How EDITGENE Supports glutathione synthase activity Research
Researchers studying glutathione synthase activity-related genes often need to determine whether a candidate gene is causally involved in glutathione homeostasis, oxidative stress responses, or disease phenotypes. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models, enabling rigorous functional studies.
Contact EDITGENE today to design your custom CRISPR model for glutathione synthase activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| GSS Knockout HEK293 Cell Line | EDJ-KQ2781 | Human | 2937 | Details Get a Quote |
| GSS Knockout HCT 116 Cell Line | EDJ-KQ22330 | Human | 2937 | Details Get a Quote |
| GSS Knockout A-549 Cell Line | EDJ-KQ23695 | Human | 2937 | Details Get a Quote |
| GSS Knockout HeLa Cell Line | EDJ-KQ23697 | Human | 2937 | Details Get a Quote |
Displaying Records 1 To 4 Of 4 Records
Frequently Asked Questions About glutathione synthase activity
What is glutathione synthase activity?
Glutathione synthase activity (GO:0004363) is the enzymatic activity that catalyzes the ATP-dependent formation of glutathione from gamma-glutamylcysteine and glycine.
What genes are involved in glutathione synthase activity?
The primary gene is GSS, which encodes glutathione synthase. Other genes such as GCLC, GCLM, and GGT1 are involved in related steps of glutathione metabolism.
What is the role of glutathione synthase in cells?
It performs the final step of glutathione synthesis, producing the major cellular antioxidant GSH, which protects against oxidative stress.
How is glutathione synthase activity regulated?
It is regulated transcriptionally by Nrf2 and other factors, and by substrate availability. Nutritional deficiencies can induce GSS expression.
What diseases are associated with glutathione synthase deficiency?
Glutathione synthetase deficiency causes hemolytic anemia, metabolic acidosis, and neurological symptoms.
Can CRISPR be used to study glutathione synthase activity?
Yes, CRISPR knockout, knock-in, and overexpression models allow precise manipulation of GSS and related genes to study their function.
What methods measure glutathione synthase activity?
Enzymatic assays, mass spectrometry, and fluorescent biosensors are commonly used.
Is glutathione synthase activity important in cancer?
Yes, elevated GSH synthesis can contribute to chemoresistance, making GSS a potential therapeutic target.
How does glutathione synthase relate to ferroptosis?
GSH depletion due to impaired synthase activity can lead to ferroptosis, an iron-dependent cell death.
What model organisms are used to study glutathione synthase?
Yeast, bacteria, mice, and human cell lines are used, each offering unique insights.
Conclusion
Glutathione synthase activity (GO:0004363) is a critical enzymatic function for glutathione biosynthesis and cellular redox balance. Its dysregulation is linked to a variety of human diseases, including glutathione synthetase deficiency, neurodegeneration, and cancer. Understanding its mechanism, regulation, and genetic control is essential for developing targeted therapies. CRISPR-based models provide powerful tools to dissect the causal roles of GSS and its regulators, and EDITGENE offers comprehensive services to support such research.
References
- 1. Lu SC. 2013. Glutathione synthesis.. Biochim Biophys Acta 1830(5):3143-53 PMID: 22995213
- 3. Sanz-Alcázar A et al.. 2024. Deciphering the ferroptosis pathways in dorsal root ganglia of Friedreich ataxia models. The role of LKB1/AMPK, KEAP1, and GSK3β in the impairment of the NRF2 response.. Redox Biol 76:103339 PMID: 39243573
- 4. Hu Q et al.. 2026. Hypericin alleviates high glucose-induced ferroptosis in cultured rat satellite glial cells via targeting P2X7R to activate the Akt/GSK3β/Nrf2 axis.. Neuropharmacology 298:111050 PMID: 42214457
- 5. Tchantchou F et al.. 2004. Increased transcription and activity of glutathione synthase in response to deficiencies in folate, vitamin E, and apolipoprotein E.. J Neurosci Res 75(4):508-15 PMID: 14743434
- 6. Ponces Freire A et al.. 2003. Anti-glycation defences in yeast.. Biochem Soc Trans 31(Pt 6):1409-12 PMID: 14641076
- 7. Lu SC. 2009. Regulation of glutathione synthesis.. Mol Aspects Med 30(1-2):42-59 PMID: 18601945
- 8. Cheng G et al.. 2017. Glutathione affects the transport activity of Rhizobium leguminosarum 3841 and is essential for efficient nodulation.. FEMS Microbiol Lett 364(8) PMID: 28333211
