GO:0004634 phosphopyruvate hydratase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004634 (phosphopyruvate hydratase activity, also called enolase activity) catalyzes the reversible dehydration of 2-phospho-D-glycerate to phosphoenolpyruvate and water, the penultimate step of glycolysis.
• The reaction is performed by enolase enzymes, principally ENO1 (alpha-enolase), ENO2 (gamma-enolase/neuron-specific enolase) and ENO3 (beta-enolase), which are encoded by distinct genes but share the same catalytic activity.
• Beyond glycolysis, enolases are multifunctional: ENO1 acts as a plasminogen receptor, participates in transcriptional regulation and is secreted or surface-exposed in tumors and immune cells.
• ENO1 and ENO2 are strongly implicated in cancer progression, metastasis and metabolic reprogramming, making GO:0004634 a high-value target for oncology research.
• Enolase activity is regulated at multiple levels, including RNA-binding autoregulation of ENO1 mRNA, post-translational modification and metabolic feedback.
• CRISPR knockout, point-mutation, knock-in and overexpression models are essential to dissect the catalytic versus non-catalytic functions of enolases in disease.
Description
Phosphopyruvate hydratase activity (GO:0004634) is a molecular function defined as the catalysis of the reaction 2-phospho-D-glycerate = phosphoenolpyruvate + H2O. This reaction is the ninth step of glycolysis and is performed by enolase enzymes, which convert 2-phosphoglycerate into phosphoenolpyruvate, the high-energy phosphate donor for pyruvate kinase. Because the reaction is reversible, the same activity also functions in gluconeogenesis, where phosphoenolpyruvate is hydrated back to 2-phosphoglycerate. The term is therefore central to carbohydrate metabolism and to the metabolic rewiring observed in cancer and other proliferative tissues. In humans, phosphopyruvate hydratase activity is carried out by three enolase isoforms: ENO1 (alpha-enolase, a widely expressed glycolytic enzyme), ENO2 (gamma-enolase, also known as neuron-specific enolase) and ENO3 (beta-enolase, predominantly muscle). Although these isoforms are encoded by separate genes, they share the same catalytic mechanism and are often co-expressed or developmentally regulated. ENO1 is particularly well studied because it is overexpressed in many tumors and also has non-glycolytic functions, including plasminogen binding, transcriptional regulation and participation in neutrophil extracellular traps. For researchers, GO:0004634 is more than a textbook glycolytic step. It is a functional node that connects metabolism, gene regulation and disease. Enolase activity is modulated by RNA-binding events, post-translational modifications and metabolic signals, and its dysregulation has been linked to cancer, immune disorders and senescence. Understanding this activity at the molecular, cellular and organismal levels requires integrated approaches, including CRISPR-based genetic models, proteomics and metabolic assays.
phosphopyruvate hydratase activity At A Glance
| GO ID | GO:0004634 |
|---|---|
| GO term | phosphopyruvate hydratase activity |
| Ontology | molecular_function |
| Synonym | enolase activity; 2-phospho-D-glycerate hydro-lyase activity; 2-phosphoglycerate dehydratase activity; gamma-enolase activity; nervous-system specific enolase |
| Major function | Catalysis of the reversible dehydration of 2-phospho-D-glycerate to phosphoenolpyruvate and water, a key step in glycolysis and gluconeogenesis |
| Reaction | 2-phospho-D-glycerate = phosphoenolpyruvate + H2O |
| Enzyme class | Hydro-lyase (dehydratase) |
| Representative genes | ENO1, ENO2, ENO3 |
| Subcellular context | Cytosol, with additional nuclear, membrane and secreted pools for ENO1 |
What Is GO:0004634?
GO:0004634, phosphopyruvate hydratase activity, is the catalytic function that converts 2-phospho-D-glycerate into phosphoenolpyruvate and water. It is a hydro-lyase (dehydratase) reaction that removes a molecule of water from the substrate, generating a carbon-carbon double bond and a high-energy phosphate compound. The activity is reversible and is shared by all enolase isoforms. In the Gene Ontology, it is classified as a molecular_function and is synonymous with enolase activity, 2-phosphoglycerate dehydratase activity and 2-phospho-D-glycerate hydro-lyase activity.
Why Is phosphopyruvate hydratase activity Important in Cell Biology?
Phosphopyruvate hydratase activity is essential for energy metabolism and metabolic flux. It sits at the penultimate step of glycolysis, controlling the production of phosphoenolpyruvate, which is required for pyruvate kinase-mediated ATP generation. Because many cancer cells rely on aerobic glycolysis (the Warburg effect), enolase activity is often upregulated and is considered a metabolic vulnerability. Beyond metabolism, enolases have acquired moonlighting functions: ENO1 can bind plasminogen, act as a transcriptional regulator and participate in immune signaling, while ENO2 is a recognized neuronal and neuroendocrine marker. Consequently, GO:0004634 is relevant to oncology, immunology, neuroscience and stem cell biology, and it is a frequent target for CRISPR-based functional studies.
• Catalyzes the ninth step of glycolysis, linking glucose metabolism to ATP production and biosynthetic precursors.
• Supports gluconeogenesis by reversing the same reaction, maintaining glucose homeostasis.
• ENO1 overexpression is observed in many cancers and correlates with poor prognosis and metabolic reprogramming.
• ENO2 (neuron-specific enolase) is a clinical biomarker for neuroendocrine tumors and neuronal injury.
• Enolase activity is regulated by RNA-binding autoregulation, as shown for ENO1 mRNA in embryonic stem cells.
• ENO1 participates in immune processes, including neutrophil extracellular trap formation and Treg differentiation during sepsis.
• Chlorogenic acid targets ENO1 to inhibit cellular senescence and skin photoaging, highlighting therapeutic potential.
• Autoantibodies against enolase are found in systemic lupus erythematosus and lupus nephritis, linking the enzyme to autoimmunity.
• Enolase isoforms are attractive targets for small-molecule inhibitors and metabolic anticancer strategies.
• CRISPR screens and knockout models are used to dissect catalytic versus non-catalytic enolase functions.
What Happens During phosphopyruvate hydratase activity?
Substrate binding and dehydration
In simple terms: The enzyme grabs a sugar-phosphate molecule and removes a water molecule from it.
Enolase binds 2-phospho-D-glycerate in its active site, where a divalent metal ion (typically Mg2+) coordinates the substrate's phosphate and hydroxyl groups. The enzyme then catalyzes the removal of a water molecule (dehydration), forming a double bond between C2 and C3 and yielding phosphoenolpyruvate. This is a reversible hydro-lyase reaction, so the same active site can hydrate phosphoenolpyruvate back to 2-phosphoglycerate during gluconeogenesis.
Metal ion cofactor and catalytic residues
In simple terms: A metal helper and specific amino acids in the enzyme's pocket make the reaction possible.
Enolase requires a divalent metal ion, usually Mg2+, for catalysis. The ion is held in place by conserved acidic residues (aspartate and glutamate) that also participate in substrate binding and stabilization of the transition state. The catalytic mechanism involves general acid-base chemistry, with a conserved lysine and histidine contributing to proton transfer. These features are shared across enolase isoforms, which is why ENO1, ENO2 and ENO3 all exhibit phosphopyruvate hydratase activity.
Glycolytic flux and metabolic integration
In simple terms: This step helps control how fast sugar is burned for energy.
The reaction sits at the penultimate step of glycolysis, immediately upstream of pyruvate kinase. Because phosphoenolpyruvate is a high-energy intermediate, its production influences the rate of ATP generation and the availability of precursors for biosynthesis. In cancer cells, increased enolase expression supports elevated glycolytic flux, and ENO1 has been shown to promote liver carcinogenesis through YAP1-dependent arachidonic acid metabolism, linking glycolysis to lipid signaling.
Moonlighting functions beyond catalysis
In simple terms: The same protein can do other jobs outside its classic enzyme role.
ENO1 and ENO2 have non-glycolytic functions. ENO1 can be expressed on the cell surface, where it acts as a plasminogen receptor, and it can also localize to the nucleus and regulate transcription. In sepsis, myeloperoxidase-anchored ENO1 mediates neutrophil extracellular trap DNA to enhance Treg differentiation via IFITM2. ENO2 drives tumor cell-induced M2 macrophage polarization to promote colorectal cancer liver metastasis. These moonlighting roles are independent of the catalytic dehydration reaction and are often studied using catalytically dead mutants.
Regulation by RNA binding and post-translational modification
In simple terms: The cell can dial enolase activity up or down by interacting with its RNA or modifying the protein.
Enolase 1 activity is subject to riboregulation: the ENO1 mRNA can bind to and inhibit its own enzyme product, creating a feedback loop that controls glycolysis and embryonic stem cell differentiation. Post-translational modifications, including phosphorylation, acetylation and oxidation, can also affect enolase activity and localization. In colorectal cancer, NSUN2-mediated m5C modification of ENO1 mRNA promotes a positive feedback loop involving YBX1, linking RNA modification to enolase expression and tumor progression.
Key Genes Involved in GO:0004634 phosphopyruvate hydratase activity
The following genes encode proteins that carry out or directly regulate phosphopyruvate hydratase activity (GO:0004634) and its associated biology.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ENO1 | Alpha-enolase; primary glycolytic enolase; plasminogen receptor; transcriptional regulator | Overexpressed in many cancers; target of chlorogenic acid; involved in senescence and immune regulation |
| ENO2 | Gamma-enolase; neuron-specific enolase; neuroendocrine marker | Drives M2 macrophage polarization in colorectal cancer liver metastasis; biomarker for neuroendocrine tumors |
| ENO3 | Beta-enolase; muscle-specific enolase | Energy metabolism in muscle; less studied in cancer but relevant to metabolic myopathies |
| NSUN2 | RNA m5C methyltransferase that modifies ENO1 mRNA | Promotes colorectal cancer progression via NSUN2/YBX1/m5C-ENO1 feedback loop |
| YBX1 | RNA-binding protein that recognizes m5C-modified ENO1 mRNA | Stabilizes ENO1 mRNA and supports tumor progression |
| YAP1 | Transcriptional co-activator downstream of ENO1 | Mediates ENO1-driven arachidonic acid metabolism in liver carcinogenesis |
| IFITM2 | Interferon-induced transmembrane protein involved in Treg differentiation | Mediates ENO1-dependent Treg differentiation during sepsis |
| MPO | Myeloperoxidase that anchors ENO1 on neutrophil extracellular traps | Links enolase to innate immune responses in sepsis |
| PKM | Pyruvate kinase, the enzyme immediately downstream of enolase | Integrates enolase output with ATP production; often studied together with ENO1 |
| HIF1A | Hypoxia-inducible factor 1-alpha | Drives glycolytic gene expression, including enolase, under hypoxia |
| MYC | Oncogenic transcription factor | Promotes glycolytic reprogramming and enolase expression in tumors |
| TP53 | Tumor suppressor | Loss of p53 alters glycolytic flux and enolase dependency |
| GAPDH | Glyceraldehyde-3-phosphate dehydrogenase, upstream glycolytic enzyme | Used as a reference in metabolic studies of enolase |
| LDHA | Lactate dehydrogenase A | Downstream of enolase; supports aerobic glycolysis in cancer |
| SLC2A1 | GLUT1 glucose transporter | Upstream of enolase; regulates glucose uptake for glycolysis |
| PGK1 | Phosphoglycerate kinase 1, upstream of enolase | Generates 2-phosphoglycerate for enolase; often co-regulated |
| PGAM1 | Phosphoglycerate mutase 1, upstream of enolase | Produces 2-phosphoglycerate; potential combination target |
| ENO1-AS1 | Antisense RNA to ENO1 | May regulate ENO1 expression; emerging research area |
How Is phosphopyruvate hydratase activity Regulated?
Phosphopyruvate hydratase activity is regulated at multiple levels. Transcriptionally, glycolytic genes including ENO1 and ENO2 are induced by hypoxia-inducible factors and oncogenic transcription factors such as MYC, supporting increased flux in proliferating cells. At the RNA level, the ENO1 mRNA can bind to and inhibit enolase 1 activity, forming a riboregulatory feedback loop that controls glycolysis and embryonic stem cell differentiation. RNA modifications, such as NSUN2-mediated m5C methylation of ENO1 mRNA, enhance its stability and translation through YBX1, creating a positive feedback loop in colorectal cancer. Post-translational modifications, including phosphorylation and oxidation, can alter enolase activity, localization and moonlighting functions. In immune cells, ENO1 is anchored by myeloperoxidase on neutrophil extracellular traps and influences Treg differentiation via IFITM2, illustrating cell-context-dependent regulation.
phosphopyruvate hydratase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ENO1 | Colorectal cancer progression via NSUN2/YBX1/m5C-ENO1 loop | ENO1 knockout and point-mutation (catalytically dead) colorectal cancer cell lines; xenograft models |
| ENO1 | Liver carcinogenesis through YAP1-dependent arachidonic acid metabolism | Liver-specific ENO1 knockout mice; YAP1 reporter assays |
| ENO2 | Colorectal cancer liver metastasis via M2 macrophage polarization | ENO2 knockout colorectal cancer cells co-cultured with macrophages; metastasis models |
| ENO1 | Sepsis and Treg differentiation via IFITM2 | ENO1 knockout neutrophils; sepsis mouse models |
| ENO1 | Cellular senescence and skin photoaging | ENO1 overexpression and knockout fibroblasts; UV-induced photoaging mouse models |
Cancer metabolism and metastasis
ENO1 and ENO2 are frequently overexpressed in tumors and support the high glycolytic flux required for rapid proliferation. In colorectal cancer, NSUN2-mediated m5C modification of ENO1 mRNA drives a positive feedback loop that promotes tumor progression. ENO1 also promotes liver carcinogenesis through YAP1-dependent arachidonic acid metabolism, linking glycolysis to lipid signaling. ENO2 drives tumor cell-induced M2 macrophage polarization, facilitating colorectal cancer liver metastasis. These findings position enolase activity as a therapeutic target and a biomarker in multiple cancers.
Immune regulation and sepsis
ENO1 is involved in innate and adaptive immune responses. During sepsis, myeloperoxidase-anchored ENO1 mediates neutrophil extracellular trap DNA to enhance Treg differentiation via IFITM2, suggesting a role in immune suppression and organ dysfunction. Autoantibodies against enolase have been detected in systemic lupus erythematosus and lupus nephritis, indicating that enolase can be an autoantigen in autoimmune disease.
Cellular senescence and aging
Chlorogenic acid has been identified as a protein target of ENO1 that inhibits cellular senescence and prevents skin photoaging in mice, highlighting a role for enolase in aging-related processes. This suggests that modulating enolase activity may have therapeutic potential in age-related skin and tissue degeneration.
Neuroendocrine and neuronal biology
ENO2, also known as neuron-specific enolase, is a well-established biomarker for neuroendocrine tumors and neuronal injury. Its expression is largely restricted to neurons and neuroendocrine cells, making it a useful diagnostic marker. The same catalytic activity (GO:0004634) is present in ENO2, but its regulation and tissue distribution differ from ENO1.
From phosphopyruvate hydratase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is enolase catalytic activity required for tumor growth? | ENO1 knockout and catalytically dead point-mutant (e.g., ENO1-E211Q) cancer cell lines |
| Does ENO1 moonlighting function depend on plasminogen binding? | Knock-in of plasminogen-binding-deficient ENO1 mutants |
| How does ENO2 affect macrophage polarization? | ENO2 knockout colorectal cancer cells co-cultured with macrophages; conditional knockout mice |
| What is the role of ENO1 in liver metabolism? | Liver-specific ENO1 knockout mice; YAP1 knockout crosses |
| How does ENO1 regulate Treg differentiation in sepsis? | ENO1 conditional knockout in neutrophils; sepsis mouse models |
| Does ENO1 mRNA autoregulation affect stem cell differentiation? | ENO1 riboregulation mutants; embryonic stem cell differentiation assays |
How to Study the phosphopyruvate hydratase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Coupled enzymatic assay | Enolase catalytic activity via NADH oxidation | Comparing wild-type and mutant enolase; inhibitor testing |
| CRISPR knockout screen | Gene essentiality and enolase dependency | Identifying cancer cell lines dependent on ENO1/ENO2 |
| RNA-seq | Transcriptional changes upon enolase perturbation | Pathway analysis in knockout or overexpression models |
| Proteomics / immunoprecipitation-MS | Protein expression, modifications and interactions | Identifying ENO1-binding partners and moonlighting functions |
| Metabolomics / isotope tracing | Glycolytic flux and metabolite levels | Assessing metabolic rewiring in cancer models |
| Western blot | Protein expression and post-translational modifications | Validating knockout, knockdown or overexpression |
| Immunofluorescence | Subcellular localization of enolase isoforms | Detecting nuclear, membrane or secreted ENO1 |
| qRT-PCR | mRNA expression of ENO1, ENO2, ENO3 | Validating CRISPR perturbations and clinical samples |
Enzymatic activity assays
Direct measurement of phosphopyruvate hydratase activity is performed using coupled enzymatic assays that monitor the conversion of 2-phosphoglycerate to phosphoenolpyruvate, often linked to lactate dehydrogenase and NADH oxidation. These assays are used to compare wild-type and mutant enolases and to test inhibitors.
CRISPR-based genetic screens
Genome-wide CRISPR knockout screens can identify enolase dependencies in cancer cell lines and other contexts. Focused screens targeting glycolytic genes, including ENO1, ENO2 and ENO3, help dissect isoform-specific roles and resistance mechanisms.
Proteomics and interactomics
Mass spectrometry-based proteomics can quantify enolase expression, post-translational modifications and interacting partners. Immunoprecipitation followed by mass spectrometry has been used to identify ENO1-binding proteins and to characterize its moonlighting functions.
Metabolic flux analysis
Seahorse extracellular flux analysis, isotope tracing and metabolomics measure glycolytic flux and pathway intermediates. These methods reveal how enolase activity affects lactate production, oxygen consumption and biosynthetic precursor availability.
How CRISPR Can Be Used to Study GO:0004634 phosphopyruvate hydratase activity
Knockout
CRISPR knockout of ENO1, ENO2 or ENO3 is used to eliminate specific enolase isoforms and assess their contribution to glycolysis, cell proliferation and disease phenotypes. For example, ENO1 knockout in cancer cell lines reduces glycolytic flux and tumor growth, while ENO2 knockout impairs M2 macrophage polarization and liver metastasis. Knockout models are essential for distinguishing isoform-specific functions.
Point Mutation
Point mutations that abolish catalytic activity (e.g., active-site mutants) allow researchers to separate the enzymatic function of enolase from its moonlighting roles. Catalytically dead ENO1 mutants can be knocked into cells to test whether plasminogen binding, transcriptional regulation or immune modulation require the hydratase activity.
Knock-in
Knock-in of tagged or mutant enolase alleles (e.g., GFP-ENO1, HA-ENO2) enables tracking of protein localization, interaction and stability. Knock-in of disease-associated or post-translational modification mutants helps define how specific residues regulate enolase activity and function.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of ENO1 or ENO2 is used to model enolase-driven metabolic reprogramming, tumor progression and immune modulation. Overexpression models complement knockout studies by revealing gain-of-function phenotypes, such as enhanced glycolysis, senescence resistance or metastasis.
How EDITGENE Supports phosphopyruvate hydratase activity Research
Researchers studying phosphopyruvate hydratase activity-related genes often need to determine whether a candidate gene is causally involved in a specific metabolic or disease phenotype. This requires precise genetic models that can distinguish catalytic activity from scaffolding or moonlighting functions. EDITGENE provides a comprehensive suite of CRISPR services to generate such models efficiently and reproducibly.
Contact EDITGENE today to design your custom CRISPR model for phosphopyruvate hydratase activity research.
Frequently Asked Questions About phosphopyruvate hydratase activity
What is phosphopyruvate hydratase activity?
Phosphopyruvate hydratase activity (GO:0004634) is the catalytic function that converts 2-phospho-D-glycerate to phosphoenolpyruvate and water. It is also known as enolase activity and is a key step in glycolysis and gluconeogenesis.
What genes are involved in phosphopyruvate hydratase activity?
The main genes are ENO1 (alpha-enolase), ENO2 (gamma-enolase) and ENO3 (beta-enolase). They encode isoforms that share the same catalytic activity but differ in tissue distribution and regulation.
What is the reaction catalyzed by enolase?
Enolase catalyzes the reversible dehydration of 2-phospho-D-glycerate to phosphoenolpyruvate and water: 2-phospho-D-glycerate = phosphoenolpyruvate + H2O.
Why is enolase important in cancer?
ENO1 and ENO2 are often overexpressed in tumors and support aerobic glycolysis, metastasis and immune evasion. They are considered metabolic targets and biomarkers in several cancers.
What is the difference between ENO1 and ENO2?
ENO1 is widely expressed and has moonlighting functions such as plasminogen binding and transcriptional regulation, while ENO2 is largely neuron-specific and serves as a neuroendocrine marker. Both catalyze the same reaction.
How is enolase activity regulated?
Enolase activity is regulated transcriptionally by hypoxia and oncogenes, at the RNA level by riboregulation and m5C modification, and post-translationally by phosphorylation and oxidation.
What diseases are linked to enolase dysfunction?
Enolase dysregulation is linked to cancer, sepsis, autoimmune diseases such as lupus, and cellular senescence. ENO1 autoantibodies are found in lupus nephritis.
How can I study phosphopyruvate hydratase activity in the lab?
Common methods include coupled enzymatic assays, CRISPR knockout or point-mutation models, proteomics, metabolomics and metabolic flux analysis.
What CRISPR models are available for enolase research?
EDITGENE offers ENO1, ENO2 and ENO3 knockout, point-mutation, knock-in, tagged knock-in and overexpression models, as well as custom CRISPR library screens.
Is enolase a good drug target?
Yes, enolase is considered a promising target in oncology and metabolic diseases. Small molecules such as chlorogenic acid have been shown to target ENO1 and inhibit senescence.
Conclusion
Phosphopyruvate hydratase activity (GO:0004634) is a fundamental molecular function that bridges energy metabolism, gene regulation and disease. The enolase isoforms ENO1, ENO2 and ENO3 catalyze the penultimate step of glycolysis and also participate in moonlighting functions that influence cancer progression, immune responses and aging. Understanding how this activity is regulated and how it contributes to disease requires precise genetic models and integrated analytical approaches. CRISPR-based knockout, point-mutation, knock-in and overexpression models, combined with metabolic and proteomic methods, provide the tools needed to dissect enolase biology and to identify new therapeutic opportunities.
References
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- 2. Li Y et al.. 2024. Role of ENO1 and its targeted therapy in tumors.. J Transl Med 22(1):1025 PMID: 39543641
- 3. Tang J et al.. 2026. ENO2 drives tumor cell-induced M2 macrophage polarization to promote colorectal cancer liver metastasis.. Signal Transduct Target Ther 11(1) PMID: 42082451
- 4. Sun L et al.. 2023. ENO1 promotes liver carcinogenesis through YAP1-dependent arachidonic acid metabolism.. Nat Chem Biol 19(12):1492-1503 PMID: 37500770
- 5. Jiang Y et al.. 2025. Myeloperoxidase-anchored ENO1 mediates neutrophil extracellular trap DNA to enhance Treg differentiation via IFITM2 during sepsis.. J Clin Invest 135(21) PMID: 40892462
- 6. Huppertz I et al.. 2022. Riboregulation of Enolase 1 activity controls glycolysis and embryonic stem cell differentiation.. Mol Cell 82(14):2666-2680.e11 PMID: 35709751
- 7. He X et al.. 2025. Identifying ENO1 as a protein target of chlorogenic acid to inhibit cellular senescence and prevent skin photoaging in mice.. Aging Cell 24(4):e14433 PMID: 39741388
- 8. Bruschi M et al.. 2021. Serum IgG2 antibody multicomposition in systemic lupus erythematosus and lupus nephritis (Part 1): cross-sectional analysis.. Rheumatology (Oxford) 60(7):3176-3188 PMID: 33374003
