GO:0030267 glyoxylate reductase (NADPH) activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0030267 defines glyoxylate reductase (NADPH) activity, the catalysis of glycolate + NADP+ = glyoxylate + NADPH + H+ [1,5].
• The enzyme is widely conserved from algae and plants to fungi and mammals, where it participates in photorespiration, glyoxylate detoxification, and hydroxypyruvate reduction [1,3,5,7].
• In humans, the enzyme is encoded by GRHPR (glyoxylate reductase/hydroxypyruvate reductase), and its dysfunction is linked to primary hyperoxaluria type 2 and altered d-aspartate metabolism [2,6].
• Plant and algal isoforms are dual-specificity NADPH(NADH)-dependent enzymes that are inhibited by acetohydroxamate, aminooxyacetate, and glycidate [1,4].
• Rice possesses two functionally redundant glyoxylate reductase isoforms that are required under high photorespiration conditions.
• CRISPR knockout, point-mutation, knock-in, and overexpression models are powerful tools to dissect the metabolic and disease roles of glyoxylate reductase (NADPH) activity [2,6,8].
Description
Glyoxylate reductase (NADPH) activity (GO:0030267) is a molecular function defined by the reversible conversion of glycolate and NADP+ to glyoxylate, NADPH, and H+ [1,5]. This activity sits at the intersection of photorespiration, one-carbon metabolism, and glyoxylate detoxification, and it has been characterized in organisms ranging from the green alga Chlamydomonas reinhardtii to spinach, rice, fungi, and humans [1,3,5,7,8]. Because glyoxylate is a reactive metabolite that can be converted to oxalate, the enzyme plays a protective role in preventing oxalate accumulation in mammals. In plants, NADPH-dependent glyoxylate reductase contributes to the photorespiratory cycle and is particularly important under conditions of high photorespiration [3,8]. Researchers study GO:0030267 to understand metabolic flux, redox balance, and the molecular basis of diseases such as primary hyperoxaluria and neurological conditions associated with d-aspartate dysregulation [2,6].
glyoxylate reductase (NADPH) activity At A Glance
| GO ID | GO:0030267 |
|---|---|
| GO term | glyoxylate reductase (NADPH) activity |
| Ontology | molecular_function |
| Synonym | glycolate:NADP+ oxidoreductase activity; glyoxylate reductase (NADP+); NADPH-glyoxylate reductase activity |
| Major function | Catalysis of glycolate + NADP+ = glyoxylate + NADPH + H+ |
| Reaction direction | Reversible; can reduce glyoxylate to glycolate or oxidize glycolate to glyoxylate |
| Cofactor | NADPH/NADP+ (some enzymes also use NADH/NAD+) |
| Subcellular location | Cytosol, chloroplast, and peroxisome (organism-dependent) |
| Representative genes | GRHPR (human), GLYR1/GLYR2 (rice), and homologs in algae, plants, and fungi |
What Is GO:0030267?
According to the QuickGO definition, glyoxylate reductase (NADPH) activity is the catalysis of the reaction: glycolate + NADP+ = glyoxylate + NADPH + H+. In other words, the enzyme uses NADPH as a cofactor to reduce glyoxylate to glycolate, or catalyzes the reverse oxidation of glycolate to glyoxylate while reducing NADP+ to NADPH. This activity is synonymous with glycolate:NADP+ oxidoreductase activity, glyoxylate reductase (NADP+), and NADPH-glyoxylate reductase activity. It belongs to the molecular_function ontology aspect and is distinct from NADH-dependent glyoxylate reductase activities, although some enzymes exhibit dual specificity for NADPH and NADH [1,5].
Why Is glyoxylate reductase (NADPH) activity Important in Cell Biology?
Glyoxylate reductase (NADPH) activity is important because it controls the cellular levels of glyoxylate, a metabolite that can be oxidized to oxalate and cause pathological calcium oxalate deposition in humans. In plants, the enzyme supports photorespiration and protects against metabolic stress under high photorespiration conditions [3,8]. In mammals, GRHPR deficiency causes primary hyperoxaluria type 2, and the enzyme also regulates free d-aspartate levels, linking it to neurological function [2,6]. Thus, GO:0030267 is relevant to metabolic disorders, plant productivity, and redox biology.
• Prevents glyoxylate accumulation and oxalate production in humans.
• Deficiency of GRHPR causes primary hyperoxaluria type 2, a rare metabolic disease.
• Regulates free d-aspartate levels in mammalian cells.
• Supports photorespiration in plants, especially under high photorespiration conditions [3,8].
• Provides a model for studying dual NADPH/NADH specificity and enzyme kinetics [1,5].
• Is inhibited by acetohydroxamate, aminooxyacetate, and glycidate, offering chemical tools for research.
• Occurs in diverse organisms, enabling comparative evolutionary studies [1,7].
• Serves as a target for metabolic engineering to improve plant stress tolerance.
• Contributes to redox balance by consuming NADPH [1,5].
• Can be studied with CRISPR models to dissect its role in disease and metabolism [2,6].
What Happens During glyoxylate reductase (NADPH) activity?
Substrate binding and cofactor interaction
In simple terms: The enzyme grabs glyoxylate and NADPH to start the reaction.
Glyoxylate reductase (NADPH) binds its substrates glyoxylate and NADPH in a sequential or random order, depending on the organism. The enzyme uses NADPH as an electron donor to reduce glyoxylate to glycolate, or in the reverse direction, oxidizes glycolate to glyoxylate while reducing NADP+ to NADPH [1,5]. Some isoforms, such as the spinach leaf enzyme, can use both NADPH and NADH, but the NADPH-dependent activity is the defining feature of GO:0030267.
Catalytic reduction of glyoxylate to glycolate
In simple terms: The enzyme converts glyoxylate into glycolate using NADPH.
In the forward direction, the enzyme catalyzes the transfer of a hydride from NADPH to glyoxylate, forming glycolate and NADP+. This reaction is part of the photorespiratory pathway in plants and algae, where it helps recycle glycolate and maintain metabolic flux [1,3]. In mammals, the same activity detoxifies glyoxylate by converting it to glycolate, preventing oxalate formation.
Reverse oxidation of glycolate to glyoxylate
In simple terms: The enzyme can also run backwards, making glyoxylate from glycolate.
The reaction is reversible, and the enzyme can oxidize glycolate to glyoxylate while reducing NADP+ to NADPH. This reverse activity may contribute to glyoxylate supply for anabolic pathways or to redox balancing. The equilibrium depends on substrate concentrations and cellular redox state.
Inhibition and regulation by small molecules
In simple terms: Certain chemicals can block the enzyme's activity.
Spinach leaf NADPH(NADH)-glyoxylate reductase is inhibited by acetohydroxamate, aminooxyacetate, and glycidate, which are structural analogs of the substrate or reaction intermediates. These inhibitors have been used to probe the enzyme's role in photorespiration and to distinguish it from other glyoxylate-metabolizing enzymes.
Physiological context in photorespiration and glyoxylate detoxification
In simple terms: The enzyme works in different pathways depending on the organism.
In plants, NADPH-dependent glyoxylate reductase is localized in leaf protoplasts and participates in photorespiratory metabolism. In rice, two isoforms are functionally redundant but required under high photorespiration conditions. In mammals, the enzyme is a major glyoxylate reductase that prevents oxalate accumulation and also regulates d-aspartate levels [2,6].
Key Genes Involved in GO:0030267 glyoxylate reductase (NADPH) activity
The following genes and proteins are directly associated with glyoxylate reductase (NADPH) activity across model organisms.
| Gene | Major Role | Research Relevance |
|---|---|---|
| GRHPR (human) | Primary glyoxylate reductase/hydroxypyruvate reductase in humans | Deficiency causes primary hyperoxaluria type 2; regulates d-aspartate [2,6] |
| GLYR1 (rice) | Glyoxylate reductase isoform 1 | Required under high photorespiration conditions |
| GLYR2 (rice) | Glyoxylate reductase isoform 2 | Functionally redundant with GLYR1 |
| HPR1 (spinach) | NADPH(NADH)-glyoxylate reductase | Model for enzyme purification and inhibition studies [4,5] |
| HPR (Chlamydomonas) | NADPH:glyoxylate reductase | Algal model for dual-specificity enzymes |
| GR (Paecilomyces thermophila) | Fungal glyoxylate reductase | First fungal enzyme with crystal structure |
| LDHA (human) | Lactate dehydrogenase A | Can metabolize glyoxylate; potential alternative route |
| LDHB (human) | Lactate dehydrogenase B | Can metabolize glyoxylate; potential alternative route |
| GRHPR homolog (plants) | Photorespiratory glyoxylate reductase | Studied in Pisum sativum protoplasts |
| NADPH-GR (spinach) | Leaf glyoxylate reductase | Immunological comparison with hydroxypyruvate reductase |
| GRHPR (mammalian cells) | Regulates d-aspartate | Knockdown alters d-aspartate levels |
| GLYR (rice) | Photorespiration | Double mutants show growth defects under high photorespiration |
| GRHPR (human) | Glyoxylate detoxification | Prevents oxalate accumulation |
| HPR (algae) | Hydroxypyruvate reductase | Partial purification and characterization |
| GR (fungi) | Glyoxylate reductase | Structural and kinetic studies |
| GRHPR (human) | NADPH-dependent reduction | Kinetic characterization with glyoxylate |
| GLYR1/2 (rice) | Redundant isoforms | Functional redundancy demonstrated by genetics |
| GRHPR (human) | d-aspartate metabolism | Links to neurological function |
How Is glyoxylate reductase (NADPH) activity Regulated?
The activity of glyoxylate reductase (NADPH) is regulated at multiple levels. In plants, expression and activity are influenced by photorespiratory conditions, with rice GLYR1 and GLYR2 being required under high photorespiration. The enzyme is also subject to feedback inhibition by metabolites such as acetohydroxamate, aminooxyacetate, and glycidate. In mammals, GRHPR activity is part of a metabolic network that includes lactate dehydrogenases, which can also metabolize glyoxylate. Additionally, GRHPR regulates free d-aspartate levels, suggesting a role in amino acid metabolism. However, specific transcriptional or post-translational regulators of GO:0030267 have not been fully defined in the cited literature.
glyoxylate reductase (NADPH) activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| GRHPR | Primary hyperoxaluria type 2 | Knockout human cell lines; point-mutation knock-in of patient variants |
| GRHPR | d-aspartate dysregulation | GRHPR knockdown/knockout in mammalian cells |
| GLYR1/GLYR2 | Photorespiration stress in rice | Double knockout rice lines |
| GRHPR | Oxalate accumulation | Overexpression and knockout in hepatocytes |
| LDHA/LDHB | Glyoxylate metabolism redundancy | Knockout and overexpression models |
Primary hyperoxaluria type 2
Mutations in GRHPR cause primary hyperoxaluria type 2, a rare autosomal recessive disorder characterized by excessive oxalate production and calcium oxalate kidney stones. The enzyme's glyoxylate reductase activity is critical for detoxifying glyoxylate; loss of function leads to glyoxylate accumulation and increased oxalate synthesis.
Neurological implications via d-aspartate regulation
GRHPR regulates the free d-aspartate level in mammalian cells. Knockdown of GRHPR alters d-aspartate concentrations, suggesting that glyoxylate reductase (NADPH) activity may influence neurological processes where d-aspartate acts as a signaling molecule.
Plant stress and photorespiration
In rice, loss of both GLYR1 and GLYR2 leads to growth defects under high photorespiration conditions, indicating that glyoxylate reductase (NADPH) activity is essential for plant stress tolerance and productivity.
From glyoxylate reductase (NADPH) activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does GRHPR loss cause oxalate accumulation? | GRHPR knockout human cell lines |
| Do patient mutations affect enzyme kinetics? | Point-mutation knock-in of GRHPR variants |
| Can wild-type GRHPR rescue the phenotype? | Knock-in of tagged GRHPR for rescue studies |
| Is GRHPR involved in d-aspartate regulation? | GRHPR overexpression and knockdown in mammalian cells |
| Are GLYR1 and GLYR2 functionally redundant? | Double knockout rice lines |
| What is the subcellular localization of the enzyme? | Tagged knock-in with fluorescent reporters |
How to Study the glyoxylate reductase (NADPH) activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NADPH oxidation assay | Enzyme activity | Kinetic characterization of purified enzyme [1,5] |
| CRISPR knockout screening | Gene essentiality and redundancy | Identifying modifiers of glyoxylate metabolism [6,8] |
| Metabolomics (LC-MS) | Glyoxylate, glycolate, oxalate, d-aspartate | Linking enzyme activity to metabolite levels [2,6] |
| X-ray crystallography | Protein structure | Understanding catalytic mechanism |
| Western blot | Protein expression | Validating knockout or overexpression |
| qRT-PCR | mRNA levels | Assessing transcriptional regulation |
| Immunolocalization | Subcellular localization | Determining organelle targeting |
| Enzyme inhibition assays | Inhibitor sensitivity | Probing active site and pathway |
Enzymatic activity assays
Direct measurement of glyoxylate reductase (NADPH) activity using spectrophotometric assays that monitor NADPH oxidation or formation at 340 nm. These assays are used to characterize purified enzymes from algae, plants, and mammals [1,5,6].
CRISPR-based genetic screens
Genome-wide knockout screens can identify genes that modulate glyoxylate reductase (NADPH) activity or its metabolic consequences. Such screens are useful for uncovering redundant pathways and synthetic lethal interactions [6,8].
Metabolomics and flux analysis
Mass spectrometry-based metabolomics can quantify glyoxylate, glycolate, oxalate, and d-aspartate levels in cells with altered glyoxylate reductase activity. This approach links enzyme activity to metabolic phenotypes [2,6].
Structural biology and crystallography
Crystal structures of glyoxylate reductases, such as the fungal enzyme from Paecilomyces thermophila, provide insights into substrate binding and catalytic mechanism.
How CRISPR Can Be Used to Study GO:0030267 glyoxylate reductase (NADPH) activity
Knockout
CRISPR knockout of GRHPR or plant GLYR genes can abolish glyoxylate reductase (NADPH) activity, leading to glyoxylate accumulation and oxalate overproduction in human cells or photorespiratory defects in rice [6,8]. Knockout models are essential for establishing causality between the enzyme and metabolic phenotypes.
Point Mutation
Point-mutation knock-in can replicate patient-specific missense mutations in GRHPR, allowing researchers to study how these variants affect enzyme kinetics, stability, and subcellular localization. Such models are valuable for understanding primary hyperoxaluria type 2.
Knock-in
Knock-in of tagged GRHPR (e.g., GFP or FLAG) enables visualization and immunoprecipitation of the enzyme in its native context. This approach helps determine subcellular localization and interaction partners.
Overexpression
Overexpression of GRHPR or plant GLYR genes can increase glyoxylate reductase (NADPH) activity, potentially reducing oxalate levels or enhancing photorespiration. Overexpression models are useful for gain-of-function studies and for testing therapeutic strategies [2,6].
How EDITGENE Supports glyoxylate reductase (NADPH) activity Research
Researchers studying glyoxylate reductase (NADPH) activity-related genes often need to determine whether a candidate gene is causally involved in metabolic pathways or disease phenotypes. CRISPR-based models provide a precise way to manipulate these genes and dissect their functions.
Contact EDITGENE today to design your custom CRISPR model for glyoxylate reductase (NADPH) activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| GRHPR Knockout HEK293 Cell Line | EDJ-KQ6568 | Human | 9380 | Details Get a Quote |
| GRHPR Knockout A-549 Cell Line | EDJ-KQ30773 | Human | 9380 | Details Get a Quote |
| GRHPR Knockout HCT 116 Cell Line | EDJ-KQ30774 | Human | 9380 | Details Get a Quote |
| GRHPR Knockout HeLa Cell Line | EDJ-KQ30775 | Human | 9380 | Details Get a Quote |
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Frequently Asked Questions About glyoxylate reductase (NADPH) activity
What is glyoxylate reductase (NADPH) activity?
It is the enzyme activity defined by GO:0030267 that catalyzes the reversible conversion of glycolate and NADP+ to glyoxylate, NADPH, and H+ [1,5].
What genes are involved in glyoxylate reductase (NADPH) activity?
Key genes include GRHPR in humans, GLYR1 and GLYR2 in rice, and homologs in spinach, algae, and fungi [1,3,5,7,8].
What is the role of GRHPR in human disease?
GRHPR deficiency causes primary hyperoxaluria type 2, and it also regulates d-aspartate levels [2,6].
How is glyoxylate reductase (NADPH) activity measured?
It is typically measured by spectrophotometric assays monitoring NADPH oxidation or formation at 340 nm [1,5].
What inhibitors target glyoxylate reductase (NADPH) activity?
Acetohydroxamate, aminooxyacetate, and glycidate inhibit the spinach leaf enzyme.
Is glyoxylate reductase (NADPH) activity present in plants?
Yes, it is found in plants such as spinach, pea, and rice, where it participates in photorespiration [3,4,5,8].
What is the difference between glyoxylate reductase and hydroxypyruvate reductase?
Some enzymes, like GRHPR, have both activities, but glyoxylate reductase (NADPH) specifically uses glyoxylate as a substrate [5,6].
Can CRISPR be used to study glyoxylate reductase (NADPH) activity?
Yes, CRISPR knockout, knock-in, and point-mutation models are powerful tools to dissect its function [2,6,8].
What are the symptoms of primary hyperoxaluria type 2?
It causes recurrent kidney stones and calcium oxalate deposition due to excessive oxalate production.
Where is glyoxylate reductase (NADPH) located in the cell?
It is found in the cytosol, chloroplast, and peroxisome depending on the organism [3,5].
Conclusion
Glyoxylate reductase (NADPH) activity (GO:0030267) is a conserved metabolic function with critical roles in glyoxylate detoxification, photorespiration, and d-aspartate regulation. Its dysfunction is linked to primary hyperoxaluria type 2 and plant stress susceptibility. By combining enzymatic assays, metabolomics, and CRISPR-based models, researchers can uncover new insights into this pathway and develop therapeutic or agricultural applications.
References
- 1. Husic DW et al.. 1987. NADH:hydroxypyruvate reductase and NADPH:glyoxylate reductase in algae: partial purification and characterization from Chlamydomonas reinhardtii.. Arch Biochem Biophys 252(2):396-408 PMID: 3545081
- 2. Katane M et al.. 2021. Glyoxylate reductase/hydroxypyruvate reductase regulates the free d-aspartate level in mammalian cells.. J Cell Biochem 122(11):1639-1652 PMID: 34289161
- 3. Kleczkowski LA et al.. 1988. Subcellular Location of NADPH-Dependent Hydroxypyruvate Reductase Activity in Leaf Protoplasts of Pisum sativum L. and Its Role in Photorespiratory Metabolism.. Plant Physiol 88(4):1182-5 PMID: 16666441
- 4. Kleczkowski LA et al.. 1987. Inhibition of Spinach Leaf NADPH(NADH)-Glyoxylate Reductase by Acetohydroxamate, Aminooxyacetate, and Glycidate.. Plant Physiol 84(3):619-23 PMID: 16665491
- 5. Kleczkowski LA et al.. 1986. Purification and characterization of a novel NADPH(NADH)-dependent glyoxylate reductase from spinach leaves. Comparison of immunological properties of leaf glyoxylate reductase and hydroxypyruvate reductase.. Biochem J 239(3):653-9 PMID: 3548703
- 6. Mdluli K et al.. 2005. A preliminary account of the properties of recombinant human Glyoxylate reductase (GRHPR), LDHA and LDHB with glyoxylate, and their potential roles in its metabolism.. Biochim Biophys Acta 1753(2):209-16 PMID: 16198644
- 7. Duan X et al.. 2014. Characterization and crystal structure of a first fungal glyoxylate reductase from Paecilomyes thermophila.. Enzyme Microb Technol 60:72-9 PMID: 24835102
- 8. Zhang Z et al.. 2020. Two glyoxylate reductase isoforms are functionally redundant but required under high photorespiration conditions in rice.. BMC Plant Biol 20(1):357 PMID: 32727356
