GO:0050207 plasmanylethanolamine desaturase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0050207 plasmanylethanolamine desaturase activity catalyzes the introduction of the vinyl ether double bond into plasmalogens, converting a 1-O-alkyl-2-acyl-phosphoethanolamine to a 1-O-alk-1-enyl-2-acyl-phosphoethanolamine using cytochrome b5 and molecular oxygen.
• The enzyme is encoded by TMEM189 (also known as PEDS1) in humans and mice, and its loss abolishes plasmalogen synthesis, leading to severe metabolic and developmental consequences.
• A conserved aspartate residue is essential for catalysis, as mutation of this residue eliminates desaturase activity.
• Plasmanylethanolamine desaturase activity is critical for maintaining cellular ether lipid homeostasis, and its dysregulation is linked to altered lipid profiles and metabolic disorders [2,8].
• TMEM189 negatively regulates autophagy by promoting ULK1 degradation, connecting plasmalogen synthesis to cellular stress responses.
• Eukaryotic plasmalogen biosynthesis likely originated via horizontal gene transfer from myxobacteria, highlighting the evolutionary importance of this activity.
Description
Plasmanylethanolamine desaturase activity (GO:0050207) is a molecular function that catalyzes the final step in the biosynthesis of plasmalogens, a class of ether phospholipids characterized by a vinyl ether bond at the sn-1 position of the glycerol backbone. This activity is essential for the production of plasmenylethanolamine, a major plasmalogen species in mammalian membranes, and its disruption leads to profound changes in lipid metabolism and cellular physiology [2,3]. The reaction consumes molecular oxygen and reduced cytochrome b5 to introduce a double bond into the alkyl chain, converting a plasmanylethanolamine to a plasmenylethanolamine. The enzyme responsible for this activity was long considered an orphan until the identification of TMEM189 (PEDS1) as the plasmanylethanolamine desaturase [3,6]. Understanding this activity is crucial for researchers studying membrane biology, lipid signaling, and diseases linked to ether lipid dysfunction, such as metabolic disorders and neurodegeneration [2,8]. The availability of genetic tools and animal models now allows detailed investigation of its mechanism, regulation, and physiological roles [1,3,4].
plasmanylethanolamine desaturase activity At A Glance
| GO ID | GO:0050207 |
|---|---|
| GO term | plasmanylethanolamine desaturase activity |
| Ontology | molecular_function |
| Synonym | 2-acyl-1-alkyl-sn-glycero-3-phosphoethanolamine desaturase activity; alkylacylglycerophosphoethanolamine desaturase activity; alkylacylglycero-phosphorylethanolamine dehydrogenase activity; plasmenylethanolamine desaturase activity |
| Major function | Catalyzes the introduction of a vinyl ether double bond into plasmanylethanolamine to form plasmenylethanolamine, a key step in plasmalogen biosynthesis. |
| Cofactors | Cytochrome b5 (Fe(II)), molecular oxygen, protons. |
| Subcellular location | Endoplasmic reticulum membrane. |
| Enzyme class | Desaturase (oxidoreductase). |
| Key gene | TMEM189 (PEDS1) in humans and mice. |
What Is GO:0050207?
Plasmanylethanolamine desaturase activity is defined as the catalysis of the reaction: 1-(1,2-saturated alkyl)-2-acyl-sn-glycero-3-phosphoethanolamine + 2 Fe(II)-[cytochrome b5] + 2 H+ + O2 = 1-O-(1Z-alkenyl)-2-acyl-sn-glycero-3-phosphoethanolamine + 2 Fe(III)-[cytochrome b5] + 2 H2O. In simpler terms, it is the enzyme activity that introduces a double bond into the alkyl chain of a plasmanylethanolamine, creating the characteristic vinyl ether linkage of plasmalogens, using cytochrome b5 as an electron donor and oxygen as an acceptor.
Why Is plasmanylethanolamine desaturase activity Important in Cell Biology?
Plasmanylethanolamine desaturase activity is essential for the biosynthesis of plasmalogens, which are abundant ether phospholipids in mammalian cell membranes, particularly in the brain, heart, and immune cells [2,3]. Plasmalogens play critical roles in membrane structure, antioxidant defense, and signaling, and their deficiency has been linked to metabolic disorders, neurodegeneration, and impaired autophagy [2,7,8]. The identification of TMEM189 as the enzyme responsible for this activity has provided a molecular handle to study ether lipid metabolism and its impact on health and disease. Moreover, the evolutionary origin of this activity via horizontal gene transfer underscores its fundamental importance in eukaryotic lipid biology.
• Plasmalogens are major components of cell membranes, and their synthesis depends on plasmanylethanolamine desaturase activity.
• Defects in plasmalogen biosynthesis cause severe neurological and metabolic disorders.
• The enzyme TMEM189 regulates autophagy by modulating ULK1 stability, linking lipid metabolism to cellular stress responses.
• Alterations in ether lipid metabolism affect the mouse lipidome and systemic lipid homeostasis.
• PEDS1 and AGMO orchestrate ether lipid homeostasis in human adipocytes and are associated with blood lipid profiles.
• The activity is a potential therapeutic target for conditions involving plasmalogen deficiency.
• Conserved aspartate residues are critical for catalysis, providing insights into the enzyme mechanism.
• Evolutionary analysis suggests that eukaryotic plasmalogen biosynthesis originated from myxobacteria via horizontal gene transfer.
• Mutant cell lines defective in plasmanylethanolamine desaturase activity have been instrumental in studying fatty acid desaturation.
• Orphan enzymes in ether lipid metabolism, including this activity, have been a focus of biochemical characterization.
What Happens During plasmanylethanolamine desaturase activity?
Substrate Recognition and Binding
In simple terms: The enzyme grabs a plasmanylethanolamine molecule and prepares it for modification.
The enzyme recognizes and binds its substrate, 1-(1,2-saturated alkyl)-2-acyl-sn-glycero-3-phosphoethanolamine, within the endoplasmic reticulum membrane. This binding is facilitated by the enzyme's active site, which positions the alkyl chain for desaturation. The conserved aspartate residue plays a crucial role in substrate binding and catalysis.
Electron Transfer from Cytochrome b5
In simple terms: The enzyme receives electrons from cytochrome b5 to power the reaction.
The desaturation reaction requires reducing equivalents, which are provided by cytochrome b5. Two molecules of reduced cytochrome b5 (Fe(II)) donate electrons to the enzyme, enabling the activation of molecular oxygen. This electron transfer is essential for the catalytic cycle, and the enzyme's interaction with cytochrome b5 is a key step in plasmalogen synthesis.
Oxygen Activation and Hydrogen Abstraction
In simple terms: Oxygen is used to remove hydrogen atoms from the alkyl chain, creating a double bond.
Molecular oxygen is activated at the enzyme's active site, likely forming a reactive iron-oxo species. This species abstracts hydrogen atoms from the alkyl chain, leading to the formation of a double bond between the alpha and beta carbons. The reaction consumes two protons and produces two water molecules. The precise mechanism involves the conserved aspartate, which may act as a base or stabilize the transition state.
Product Formation and Release
In simple terms: The modified lipid, now a plasmenylethanolamine, is released for use in the cell.
Following desaturation, the product 1-O-(1Z-alkenyl)-2-acyl-sn-glycero-3-phosphoethanolamine (plasmenylethanolamine) is released from the enzyme. This plasmalogen is then transported to various cellular membranes or further remodeled. The enzyme itself remains in the endoplasmic reticulum membrane, ready for another catalytic cycle.
Key Genes Involved in GO:0050207 plasmanylethanolamine desaturase activity
The following genes and proteins are directly involved in plasmanylethanolamine desaturase activity or its regulation.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TMEM189 (PEDS1) | Encodes the plasmanylethanolamine desaturase enzyme that catalyzes the vinyl ether bond formation. | Knockout leads to loss of plasmalogens; key target for studying ether lipid metabolism. |
| CYB5A | Cytochrome b5, provides electrons for the desaturation reaction. | Essential cofactor; knockdown reduces desaturase activity. |
| AGMO | Alkylglycerol monooxygenase, involved in ether lipid degradation. | Works with PEDS1 to maintain ether lipid homeostasis; associated with blood lipid profiles. |
| ULK1 | Autophagy initiator kinase, negatively regulated by TMEM189. | Links plasmalogen synthesis to autophagy regulation. |
| FAR1 | Fatty acyl-CoA reductase, involved in fatty alcohol synthesis for ether lipids. | Provides precursors for plasmalogen biosynthesis. |
| FAR2 | Fatty acyl-CoA reductase, involved in fatty alcohol synthesis. | Contributes to ether lipid precursor supply. |
| GNPAT | Dihydroxyacetone phosphate acyltransferase, peroxisomal enzyme in ether lipid synthesis. | Mutations cause rhizomelic chondrodysplasia punctata. |
| AGPS | Alkylglycerone phosphate synthase, peroxisomal enzyme. | Defects lead to plasmalogen deficiency. |
| PEX7 | Peroxisomal targeting signal 2 receptor, required for import of ether lipid enzymes. | Mutations cause peroxisome biogenesis disorders. |
| PEX5 | Peroxisomal targeting signal 1 receptor. | Required for peroxisomal import of ether lipid enzymes. |
| CHPT1 | Choline phosphotransferase, involved in phosphatidylcholine synthesis. | May influence plasmalogen remodeling. |
| CEPT1 | Choline/ethanolamine phosphotransferase, involved in phospholipid synthesis. | Affects plasmalogen precursor availability. |
| PLA2G6 | Phospholipase A2, involved in phospholipid remodeling. | Mutations cause neurodegeneration with brain iron accumulation. |
| MBOAT1 | Membrane-bound O-acyltransferase, may acylate plasmalogens. | Potential role in plasmalogen maturation. |
| MBOAT2 | Membrane-bound O-acyltransferase. | Potential role in plasmalogen remodeling. |
| LPCAT3 | Lysophosphatidylcholine acyltransferase 3, involved in phospholipid remodeling. | May affect plasmalogen fatty acid composition. |
| SCD1 | Stearoyl-CoA desaturase 1, introduces double bonds in fatty acids. | Mutant studies link fatty acid desaturation to plasmanylethanolamine desaturase. |
| TMEM189-AS1 | Antisense RNA to TMEM189, may regulate its expression. | Potential regulatory role in plasmalogen synthesis. |
How Is plasmanylethanolamine desaturase activity Regulated?
Plasmanylethanolamine desaturase activity is regulated at multiple levels. The expression of TMEM189 (PEDS1) is subject to transcriptional control, and its activity depends on the availability of cytochrome b5 and oxygen. Additionally, TMEM189 negatively regulates the stability of ULK1 protein, thereby influencing autophagy, which in turn can affect lipid metabolism. Ether lipid homeostasis is also maintained through the coordinated action of PEDS1 and AGMO, and alterations in this balance are associated with changes in blood lipid profiles. Furthermore, the enzyme's activity may be influenced by the availability of substrates and the redox state of the cell, as it requires reduced cytochrome b5.
plasmanylethanolamine desaturase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| TMEM189 (PEDS1) | Plasmalogen deficiency, metabolic disorders, altered autophagy [3,7,8] | Knockout mouse, human adipocyte cell lines [3,8] |
| AGMO | Ether lipid imbalance, dyslipidemia | Knockout mouse, adipocyte models |
| GNPAT | Rhizomelic chondrodysplasia punctata | Patient fibroblasts, knockout cell lines |
| AGPS | Plasmalogen deficiency, peroxisomal disorders | Knockout mouse, patient cells |
| PEX7 | Peroxisome biogenesis disorders | Patient fibroblasts, knockout models |
Metabolic Disorders and Lipid Homeostasis
Alterations in plasmanylethanolamine desaturase activity lead to changes in ether lipid metabolism, which can affect systemic lipid profiles. Studies in human adipocytes show that PEDS1 and AGMO orchestrate ether lipid homeostasis and are associated with blood lipid profiles, suggesting a role in metabolic disorders such as dyslipidemia and obesity. Mouse models with altered ether lipid metabolism exhibit significant changes in the lipidome, further supporting the link between this activity and metabolic health.
Neurodegeneration and Brain Function
Plasmalogens are highly enriched in the brain, and their deficiency has been implicated in neurodegenerative diseases. Mutations in genes required for plasmalogen biosynthesis, including those upstream of plasmanylethanolamine desaturase, cause peroxisomal disorders with severe neurological symptoms. The loss of plasmalogens can lead to membrane dysfunction and increased oxidative stress, contributing to neuronal damage.
Autophagy and Cellular Stress
TMEM189, the enzyme responsible for plasmanylethanolamine desaturase activity, negatively regulates the stability of ULK1 protein, a key initiator of autophagy. This links plasmalogen synthesis to the regulation of autophagy, a process critical for cellular homeostasis and survival under stress. Dysregulation of this pathway may contribute to diseases characterized by impaired autophagy, such as cancer and neurodegeneration.
From plasmanylethanolamine desaturase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of TMEM189 loss on plasmalogen levels? | TMEM189 knockout cell lines and mice |
| How does the conserved aspartate mutation affect enzyme activity? | Point mutation (D→N) knock-in cell lines |
| Does TMEM189 regulate autophagy through ULK1? | TMEM189 knockout with ULK1 overexpression or knockdown |
| How does PEDS1 overexpression affect lipid profiles? | PEDS1 overexpression in adipocytes or hepatocytes |
| What is the role of TMEM189 in metabolic tissues? | Tissue-specific knockout mice (adipose, liver) |
| Can plasmalogen synthesis be restored by PEDS1 knock-in? | Knock-in of wild-type PEDS1 in knockout cells |
How to Study the plasmanylethanolamine desaturase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Lipidomics (LC-MS/MS) | Plasmalogen and ether lipid species | Quantifying plasmenylethanolamine levels in cells/tissues [2,8] |
| Enzyme activity assay | Desaturase activity using radiolabeled substrate | Characterizing wild-type and mutant enzymes [1,3] |
| CRISPR-Cas9 knockout | Loss of gene function | Creating TMEM189 knockout cells to study plasmalogen loss |
| CRISPR point mutation | Specific amino acid substitution | Testing the role of conserved aspartate |
| Western blot | Protein expression and stability | Assessing ULK1 levels and autophagy markers |
| qRT-PCR | mRNA expression levels | Measuring TMEM189 and related gene expression |
| Immunofluorescence | Subcellular localization | Visualizing TMEM189 in the endoplasmic reticulum |
| Cycloheximide chase | Protein half-life | Determining ULK1 stability regulated by TMEM189 |
Lipidomics and Mass Spectrometry
Mass spectrometry-based lipidomics is the primary method to measure plasmalogen levels and assess plasmanylethanolamine desaturase activity. By quantifying plasmenylethanolamine and its precursor, researchers can determine enzyme activity in cells and tissues [2,8]. This approach is essential for studying the impact of genetic manipulations on ether lipid metabolism.
Enzyme Activity Assays
In vitro enzyme assays using radiolabeled substrates or fluorescent probes can directly measure plasmanylethanolamine desaturase activity. These assays typically use microsomal fractions and require cytochrome b5 and NADH or NADPH as electron donors [3,4]. Such assays are valuable for characterizing mutant enzymes and testing inhibitors.
CRISPR-Cas9 Genome Editing
CRISPR-Cas9 knockout, point mutation, and knock-in strategies are used to create isogenic cell lines with defined alterations in TMEM189 or related genes. These models allow precise dissection of the enzyme's role in plasmalogen synthesis and cellular physiology [3,7].
Autophagy and Protein Stability Assays
Western blotting for ULK1, LC3, and p62, along with cycloheximide chase assays, can assess how TMEM189 modulates ULK1 stability and autophagy. These methods link plasmanylethanolamine desaturase activity to cellular stress responses.
How CRISPR Can Be Used to Study GO:0050207 plasmanylethanolamine desaturase activity
Knockout
CRISPR-Cas9 knockout of TMEM189 (PEDS1) completely abolishes plasmanylethanolamine desaturase activity, leading to the loss of plasmalogens and accumulation of plasmanylethanolamine precursors. These knockout models are invaluable for studying the physiological consequences of plasmalogen deficiency, including changes in lipidome, autophagy, and metabolic profiles [3,7].
Point Mutation
Point mutations in the catalytic domain of TMEM189, such as the conserved aspartate residue, can be introduced using CRISPR-Cas9 homology-directed repair. These models allow researchers to dissect the enzymatic mechanism and confirm the essential role of specific residues in catalysis.
Knock-in
Knock-in of tagged or wild-type TMEM189 into a safe harbor locus or the endogenous locus enables controlled expression and functional rescue experiments. Tagged knock-in (e.g., FLAG or GFP) facilitates protein localization and interaction studies, while wild-type knock-in can restore plasmalogen synthesis in knockout cells.
Overexpression
Overexpression of TMEM189 using CRISPR activation or lentiviral vectors can increase plasmanylethanolamine desaturase activity, leading to elevated plasmalogen levels. This approach is useful for studying the effects of enhanced ether lipid synthesis on cellular functions and for producing plasmalogen-rich membranes.
How EDITGENE Supports plasmanylethanolamine desaturase activity Research
Researchers studying plasmanylethanolamine desaturase activity-related genes often need to determine whether a candidate gene is causally involved in plasmalogen synthesis, metabolic regulation, or autophagy. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell models, enabling rigorous functional studies of TMEM189 and its network.
Contact EDITGENE today to design your custom CRISPR model for plasmanylethanolamine desaturase activity research.
Frequently Asked Questions About plasmanylethanolamine desaturase activity
What is plasmanylethanolamine desaturase activity?
It is the enzyme activity that introduces a vinyl ether double bond into plasmanylethanolamine, forming plasmenylethanolamine, a key plasmalogen. The reaction uses cytochrome b5 and oxygen.
What genes are involved in plasmanylethanolamine desaturase activity?
The primary gene is TMEM189 (also known as PEDS1), which encodes the enzyme. Cytochrome b5 (CYB5A) provides electrons, and other ether lipid genes like AGMO, FAR1, and GNPAT are involved in related pathways [3,6,8].
What is the function of TMEM189?
TMEM189 encodes plasmanylethanolamine desaturase, which catalyzes the final step in plasmalogen biosynthesis. It also negatively regulates ULK1 stability and autophagy [3,7].
How is plasmanylethanolamine desaturase activity measured?
It is typically measured using mass spectrometry-based lipidomics to quantify plasmenylethanolamine, or by in vitro enzyme assays with radiolabeled substrates [2,3].
What diseases are associated with plasmanylethanolamine desaturase deficiency?
Deficiency leads to plasmalogen loss, which is linked to metabolic disorders, dyslipidemia, and neurodegeneration. Mutations in upstream ether lipid genes cause peroxisomal disorders [2,6,8].
What is the role of the conserved aspartate in plasmanylethanolamine desaturase?
The conserved aspartate residue is essential for catalytic activity; mutation to asparagine abolishes enzyme function.
How does TMEM189 regulate autophagy?
TMEM189 negatively regulates the stability of ULK1 protein, thereby inhibiting autophagy initiation.
Can plasmanylethanolamine desaturase activity be targeted for therapy?
Modulating this activity could potentially treat plasmalogen deficiency disorders, but further research is needed to develop safe therapeutic strategies.
What model systems are used to study plasmanylethanolamine desaturase?
Common models include TMEM189 knockout mice, human cell lines (e.g., adipocytes, fibroblasts), and mutant cell lines defective in desaturase activity [2,3,4].
What is the evolutionary origin of plasmanylethanolamine desaturase?
Eukaryotic plasmalogen biosynthesis likely originated via horizontal gene transfer from myxobacteria, as suggested by phylogenetic analysis.
Conclusion
Plasmanylethanolamine desaturase activity (GO:0050207) is a critical enzymatic function in ether lipid metabolism, responsible for the synthesis of plasmalogens. The identification of TMEM189 as the responsible gene has opened new avenues for understanding plasmalogen biology and its links to metabolic disorders, neurodegeneration, and autophagy. Continued research using advanced CRISPR models and lipidomics will further elucidate the regulation and therapeutic potential of this activity.
References
- 1. Werner ER et al.. 2022. Essential role of a conserved aspartate for the enzymatic activity of plasmanylethanolamine desaturase.. Cell Mol Life Sci 79(4):214 PMID: 35347434
- 2. Lackner K et al.. 2023. Alterations in ether lipid metabolism and the consequences for the mouse lipidome.. Biochim Biophys Acta Mol Cell Biol Lipids 1868(4):159285 PMID: 36690320
- 3. Werner ER et al.. 2020. The TMEM189 gene encodes plasmanylethanolamine desaturase which introduces the characteristic vinyl ether double bond into plasmalogens.. Proc Natl Acad Sci U S A 117(14):7792-7798 PMID: 32209662
- 4. Rangaswamy S et al.. 1994. Fatty acid desaturation in an animal cell mutant defective in plasmanylethanolamine desaturase.. Biochim Biophys Acta 1211(1):79-84 PMID: 8123685
- 5. Trinidad-Barnech JM et al.. 2026. Origin of eukaryotic plasmalogen biosynthesis by horizontal gene transfer from myxobacteria.. Proc Natl Acad Sci U S A 123(12):e2529738123 PMID: 41843685
- 6. Watschinger K et al.. 2013. Orphan enzymes in ether lipid metabolism.. Biochimie 95(1):59-65 PMID: 22771767
- 7. Yu J et al.. 2022. TMEM189 negatively regulates the stability of ULK1 protein and cell autophagy.. Cell Death Dis 13(4):316 PMID: 35393404
- 8. Sailer S et al.. 2026. Make or break - PEDS1 and AGMO orchestrate ether lipid homeostasis in human adipocytes and are associated with blood lipid profiles.. J Transl Med 24(1):262 PMID: 41580817
