GO:0004657 proline dehydrogenase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004657 proline dehydrogenase activity catalyzes the oxidation of L-proline to (S)-1-pyrroline-5-carboxylate using a quinone electron acceptor.
• The enzyme is also known as proline oxidase (POX) and is encoded by PRODH in humans, with roles in mitochondrial redox balance and apoptosis.
• Proline dehydrogenase activity links proline catabolism to cancer, collagen metabolism, and autophagy regulation.
• In bacteria such as Escherichia coli, proline dehydrogenase activity of PutA is required for induction of the put operon.
• In Mycobacterium tuberculosis, proline dehydrogenase and pyrroline-5-carboxylate dehydrogenase exhibit substrate channeling.
• Accurate assays are essential to distinguish proline dehydrogenase from pyrroline-5-carboxylate reductase activities.
Description
Proline dehydrogenase activity (GO:0004657) is a molecular function that catalyzes the oxidation of L-proline to (S)-1-pyrroline-5-carboxylate, transferring electrons to a quinone acceptor and releasing a quinol and a proton. This reaction is the first and rate-limiting step in proline catabolism, connecting proline availability to mitochondrial energy production and redox signaling. In humans, the enzyme is often referred to as proline oxidase (POX) and is encoded by the PRODH gene, where it plays critical roles in apoptosis, autophagy, and cancer metabolism. Researchers study this activity to understand how proline metabolism contributes to diseases such as cancer, and to develop inhibitors or biosensors for therapeutic and diagnostic applications. The enzyme is also a target for suicide inhibitors like N-propargylglycine, which shows anticancer activity and mitohormetic properties. In bacteria, proline dehydrogenase activity is essential for proline utilization and gene regulation, as seen with the PutA repressor in Escherichia coli. Overall, GO:0004657 represents a key enzymatic activity at the interface of amino acid metabolism, cellular stress responses, and disease.
proline dehydrogenase activity At A Glance
| GO ID | GO:0004657 |
|---|---|
| GO term | proline dehydrogenase activity |
| Ontology | molecular_function |
| Synonym | L-proline dehydrogenase activity, proline oxidase activity |
| Major function | Catalyzes the oxidation of L-proline to (S)-1-pyrroline-5-carboxylate using a quinone electron acceptor |
| Reaction | L-proline + a quinone = (S)-1-pyrroline-5-carboxylate + a quinol + H+ |
| Cofactor | Quinone (e.g., ubiquinone or menaquinone depending on organism) |
| Localization | Mitochondrial inner membrane in eukaryotes; cytoplasmic in some bacteria |
| Related genes | PRODH (human), PUT1/PUTA (bacteria), SlPRODH (plants) |
What Is GO:0004657?
Proline dehydrogenase activity (GO:0004657) is defined as the catalysis of the reaction: L-proline + a quinone = (S)-1-pyrroline-5-carboxylate + a quinol + H+. This activity uses a quinone as an electron acceptor and is synonymous with L-proline dehydrogenase activity and proline oxidase activity. It is a molecular function that enables the oxidative deamination of proline, initiating proline degradation.
Why Is proline dehydrogenase activity Important in Cell Biology?
Proline dehydrogenase activity is important because it controls the first step of proline catabolism, influencing cellular redox balance, energy production, and stress responses. In humans, altered activity of this enzyme is linked to cancer progression, where it can promote apoptosis or autophagy depending on context. In bacteria, it regulates gene expression and proline utilization. The enzyme is also a target for anticancer drugs and a tool for biosensing L-proline in biological fluids.
• Regulates proline catabolism and mitochondrial redox homeostasis.
• Plays a dual role in cancer, promoting either apoptosis or autophagy.
• Required for induction of the put operon in Escherichia coli.
• Exhibits substrate channeling with pyrroline-5-carboxylate dehydrogenase in Mycobacterium tuberculosis.
• Targeted by suicide inhibitors like N-propargylglycine for anticancer therapy.
• Used in electrochemical biosensors for L-proline detection.
• Involved in collagen metabolism and apoptosis/autophagy interface.
• Essential for accurate assay development to distinguish from P5C reductase.
• Contributes to brain-enhancing mitohormesis properties.
• Serves as a model for studying quinone-dependent dehydrogenases.
Molecular Mechanism of proline dehydrogenase activity
Substrate Binding and Oxidation
In simple terms: The enzyme grabs proline and removes electrons from it.
Proline dehydrogenase binds L-proline and catalyzes its oxidation to (S)-1-pyrroline-5-carboxylate. This step involves the transfer of electrons to a quinone acceptor, producing a quinol and a proton. The reaction is stereospecific and requires a flavin adenine dinucleotide (FAD) cofactor in many enzymes, although the quinone is the direct electron acceptor in the overall reaction.
Electron Transfer to Quinone
In simple terms: Electrons are passed to a quinone molecule.
The electrons removed from proline are transferred to a quinone (e.g., ubiquinone in eukaryotes or menaquinone in bacteria), reducing it to a quinol. This step links proline oxidation to the respiratory chain and maintains redox balance. In Mycobacterium tuberculosis, proline dehydrogenase and pyrroline-5-carboxylate dehydrogenase form a complex that enables substrate channeling, preventing release of the reactive intermediate.
Product Release and Channeling
In simple terms: The product is handed off to the next enzyme.
(S)-1-Pyrroline-5-carboxylate is the product of proline dehydrogenase activity. In some organisms, it is directly channeled to pyrroline-5-carboxylate dehydrogenase for further oxidation to glutamate, as shown in Mycobacterium tuberculosis. In plants, appropriate activity assays are crucial to distinguish proline dehydrogenase from pyrroline-5-carboxylate reductase, which catalyzes the reverse reaction.
Regulation by PutA in Bacteria
In simple terms: In bacteria, the enzyme also controls gene expression.
In Escherichia coli, proline dehydrogenase activity is carried out by the bifunctional PutA protein, which also acts as a transcriptional repressor. Proline dehydrogenase activity of PutA is required for induction of the put operon by proline, linking enzymatic activity to gene regulation.
Inhibition and Chemical Probes
In simple terms: Certain molecules can block the enzyme.
N-Propargylglycine acts as a suicide inhibitor of proline dehydrogenase, showing anticancer activity and brain-enhancing mitohormesis properties. Such inhibitors are valuable for probing the enzyme's role in disease and for developing therapeutics.
Key Genes Involved in GO:0004657 proline dehydrogenase activity
The following genes and proteins are directly associated with proline dehydrogenase activity (GO:0004657) based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PRODH (human) | Encodes proline dehydrogenase (proline oxidase) | Linked to cancer, apoptosis, autophagy, and mitochondrial redox |
| PUTA (E. coli) | Bifunctional proline dehydrogenase and transcriptional repressor | Required for put operon induction by proline |
| PUT1 (yeast) | Proline dehydrogenase | Model for proline catabolism and mitochondrial function |
| SlPRODH (tomato) | Proline dehydrogenase in plants | Assay development and stress responses |
| MtPRODH (M. tuberculosis) | Proline dehydrogenase | Substrate channeling with P5C dehydrogenase |
| P5CDH (M. tuberculosis) | Pyrroline-5-carboxylate dehydrogenase | Channeling partner for proline dehydrogenase |
| PRODH (mouse) | Proline dehydrogenase | Model for cancer and metabolism studies |
| POX (Drosophila) | Proline oxidase | Model for redox signaling |
| PRODH (Arabidopsis) | Proline dehydrogenase | Plant stress and proline metabolism |
| P5CR (plants) | Pyrroline-5-carboxylate reductase | Distinct from proline dehydrogenase in assays |
| PRODH (zebrafish) | Proline dehydrogenase | Developmental and metabolic studies |
| PRODH (rat) | Proline dehydrogenase | Biochemical characterization |
| PRODH (C. elegans) | Proline dehydrogenase | Aging and stress response |
| PRODH (bovine) | Proline dehydrogenase | Structural studies |
| PRODH (human) variants | Point mutations in PRODH | Associated with hyperprolinemia and schizophrenia |
How Is proline dehydrogenase activity Regulated?
Proline dehydrogenase activity is regulated at multiple levels. In Escherichia coli, the bifunctional PutA protein represses the put operon in the absence of proline, and its proline dehydrogenase activity is required for induction. In humans, PRODH expression is regulated by p53 and PPARγ, and its activity is influenced by mitochondrial redox state and substrate availability. Collagen metabolism can regulate proline dehydrogenase/proline oxidase-dependent apoptosis and autophagy, suggesting crosstalk with extracellular matrix remodeling. The enzyme is also subject to inhibition by N-propargylglycine, which irreversibly inactivates it.
proline dehydrogenase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PRODH | Cancer (apoptosis/autophagy) | PRODH knockout or overexpression in cancer cell lines |
| PRODH | Hyperprolinemia/schizophrenia | Point mutation knock-in in mice |
| PUTA | Bacterial proline utilization | E. coli putA mutants |
| MtPRODH | Tuberculosis | M. tuberculosis knockout or channeling assays |
| PRODH | Collagen metabolism disorders | Fibroblast models with PRODH modulation |
Cancer
Proline dehydrogenase (proline oxidase) has context-dependent roles in cancer. It can promote apoptosis and inhibit tumor growth in some settings, while in others it supports autophagy and cancer cell survival. N-Propargylglycine, a suicide inhibitor, shows anticancer activity, highlighting the enzyme as a therapeutic target.
Metabolic and Collagen Disorders
The prolidase-proline dehydrogenase/proline oxidase-collagen biosynthesis axis is a potential interface of apoptosis and autophagy, linking proline metabolism to collagen disorders and tissue remodeling.
Hyperprolinemia and Neurological Disorders
Mutations in PRODH can lead to hyperprolinemia, which is associated with neurological phenotypes such as schizophrenia, although the exact mechanisms remain under investigation.
Infectious Diseases
In Mycobacterium tuberculosis, proline dehydrogenase and pyrroline-5-carboxylate dehydrogenase exhibit substrate channeling, which may be important for pathogenesis and is a potential drug target.
From proline dehydrogenase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does PRODH loss affect tumor growth? | PRODH knockout cancer cell lines and xenografts |
| How does a specific PRODH mutation affect activity? | Point mutation knock-in in cell lines |
| Can PRODH be targeted for anticancer therapy? | Overexpression and inhibitor studies |
| What is the role of proline dehydrogenase in bacterial gene regulation? | PUTA knockout in E. coli |
| Does substrate channeling occur in M. tuberculosis? | Knockout of MtPRODH and P5CDH |
| How is proline dehydrogenase activity regulated by collagen? | Collagen matrix models with PRODH modulation |
How to Study the proline dehydrogenase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzymatic assay | Proline dehydrogenase activity | Distinguishing from P5C reductase |
| Electrochemical biosensor | L-proline concentration | Detection in biological fluids |
| CRISPR knockout | Loss of gene function | Cancer and bacterial studies |
| CRISPR knock-in | Specific mutations | Hyperprolinemia models |
| Overexpression | Gain of function | Apoptosis/autophagy studies |
| Inhibitor treatment | Enzyme inhibition | Anticancer drug development |
| Substrate channeling assay | Protein-protein interaction | M. tuberculosis studies |
Enzymatic Activity Assays
Appropriate activity assays are crucial for the specific determination of proline dehydrogenase and pyrroline-5-carboxylate reductase activities. These assays typically measure the reduction of a quinone acceptor or the formation of (S)-1-pyrroline-5-carboxylate.
Electrochemical Biosensing
Proline dehydrogenase-entrapped mesoporous magnetic silica nanomaterials have been used for electrochemical biosensing of L-proline in biological fluids, offering a sensitive detection method.
Genetic Knockout and Knock-in Models
CRISPR-Cas9 knockout and knock-in models are used to study the loss- or gain-of-function of PRODH and its homologs in cancer, metabolism, and bacterial pathogenesis.
Inhibitor Studies
Suicide inhibitors like N-propargylglycine are used to probe the enzyme's role in cancer and mitohormesis, providing insights into therapeutic potential.
How CRISPR Can Be Used to Study GO:0004657 proline dehydrogenase activity
Knockout
CRISPR knockout of PRODH or its homologs is used to eliminate proline dehydrogenase activity, enabling studies of its role in cancer, metabolism, and bacterial gene regulation.
Point Mutation
Point mutation knock-in models can mimic naturally occurring PRODH variants, such as those associated with hyperprolinemia, to study their impact on enzyme activity and disease.
Knock-in
Knock-in of tagged PRODH allows for localization and interaction studies, while knock-in of disease-associated mutations provides mechanistic insights.
Overexpression
Overexpression of PRODH is used to study its pro-apoptotic and autophagy-inducing effects, as well as its impact on mitochondrial redox.
How EDITGENE Supports proline dehydrogenase activity Research
Researchers studying proline dehydrogenase activity-related genes often need to determine whether a candidate gene is causally involved in a specific phenotype, such as cancer cell survival or bacterial pathogenesis. This requires precise genetic models that can knockout, mutate, or overexpress the gene of interest.
Contact EDITGENE today to design your custom CRISPR model for proline dehydrogenase activity research.
Frequently Asked Questions About proline dehydrogenase activity
What is proline dehydrogenase activity?
Proline dehydrogenase activity (GO:0004657) is the catalysis of L-proline oxidation to (S)-1-pyrroline-5-carboxylate using a quinone acceptor.
What genes are involved in proline dehydrogenase activity?
Key genes include PRODH in humans, PUTA in E. coli, PUT1 in yeast, and MtPRODH in Mycobacterium tuberculosis.
What is the role of proline dehydrogenase in cancer?
It can promote apoptosis or autophagy depending on context, and inhibitors like N-propargylglycine show anticancer activity.
How is proline dehydrogenase activity measured?
It is measured by enzymatic assays monitoring quinone reduction or P5C formation, and by electrochemical biosensors.
What is the difference between proline dehydrogenase and proline oxidase?
They are synonyms for the same activity, encoded by PRODH in humans.
What diseases are associated with proline dehydrogenase mutations?
Mutations in PRODH are linked to hyperprolinemia and schizophrenia, and altered activity is implicated in cancer.
How does proline dehydrogenase regulate bacterial gene expression?
In E. coli, the proline dehydrogenase activity of PutA is required for induction of the put operon by proline.
What is substrate channeling in proline dehydrogenase?
In M. tuberculosis, proline dehydrogenase and P5C dehydrogenase form a complex that channels the intermediate, preventing its release.
Can proline dehydrogenase be targeted for therapy?
Yes, suicide inhibitors like N-propargylglycine are being explored for anticancer therapy.
What model systems are used to study proline dehydrogenase activity?
Common models include CRISPR knockout/knock-in cell lines, E. coli, M. tuberculosis, and mouse models.
Conclusion
Proline dehydrogenase activity (GO:0004657) is a fundamental enzymatic function that bridges proline metabolism with cellular redox, apoptosis, and autophagy. Its roles in cancer, bacterial pathogenesis, and metabolic disorders make it a compelling target for research and therapeutic development. Understanding its mechanism and regulation requires precise genetic models and activity assays, which are essential for advancing the field.
References
- 1. Liu W et al.. 2012. Proline dehydrogenase (oxidase) in cancer.. Biofactors 38(6):398-406 PMID: 22886911
- 2. Zareba I et al.. 2016. Prolidase-proline dehydrogenase/proline oxidase-collagen biosynthesis axis as a potential interface of apoptosis/autophagy.. Biofactors 42(4):341-8 PMID: 27040799
- 3. Muro-Pastor AM et al.. 1995. Proline dehydrogenase activity of the transcriptional repressor PutA is required for induction of the put operon by proline.. J Biol Chem 270(17):9819-27 PMID: 7730362
- 4. Palka J et al.. 2021. Collagen metabolism as a regulator of proline dehydrogenase/proline oxidase-dependent apoptosis/autophagy.. Amino Acids 53(12):1917-1925 PMID: 33818628
- 5. Scott GK et al.. 2021. N-Propargylglycine: a unique suicide inhibitor of proline dehydrogenase with anticancer activity and brain-enhancing mitohormesis properties.. Amino Acids 53(12):1927-1939 PMID: 34089390
- 6. Kumar S et al.. 2023. Proline Dehydrogenase and Pyrroline 5 Carboxylate Dehydrogenase from Mycobacterium tuberculosis: Evidence for Substrate Channeling.. Pathogens 12(9) PMID: 37764979
- 7. Lebreton S et al.. 2020. Appropriate Activity Assays Are Crucial for the Specific Determination of Proline Dehydrogenase and Pyrroline-5-Carboxylate Reductase Activities.. Front Plant Sci 11:602939 PMID: 33424902
- 8. Hasanzadeh M et al.. 2017. Proline dehydrogenase-entrapped mesoporous magnetic silica nanomaterial for electrochemical biosensing of L-proline in biological fluids.. Enzyme Microb Technol 105:64-76 PMID: 28756863
