GO:0018401 peptidyl-proline hydroxylation to 4-hydroxy-L-proline: Collagen Modification Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0018401 describes the enzymatic conversion of peptidyl-proline to 4-hydroxy-L-proline, a critical post-translational modification in collagen and other proteins [1, 5].
• The reaction is catalyzed by procollagen-proline,2-oxoglutarate-4-dioxygenase (prolyl 4-hydroxylase), which requires 2-oxoglutarate, iron, and ascorbate as cofactors [6, 7].
• This modification is essential for collagen triple-helix stability and is conserved from plants to humans [2, 4].
• In plants, prolyl 4-hydroxylases regulate root hair expansion and cell wall integrity.
• Bacterial prolyl 4-hydroxylases can modify collagen-like substrates with asymmetric patterns, suggesting diverse substrate recognition.
• Dysregulation of peptidyl-proline hydroxylation is linked to fibrotic diseases and cancer, making it a therapeutic target [5, 7].
Description
Peptidyl-proline hydroxylation to 4-hydroxy-L-proline (GO:0018401) is a post-translational modification that converts specific proline residues within peptides to 4-hydroxy-L-proline [1, 5]. This reaction is catalyzed by procollagen-proline,2-oxoglutarate-4-dioxygenase, commonly known as prolyl 4-hydroxylase, and is a key step in collagen biosynthesis [6, 7]. The modification is essential for the stability of the collagen triple helix, as hydroxyproline residues form hydrogen bonds that reinforce the structure. Researchers study this process to understand connective tissue disorders, fibrosis, and cancer progression, as well as plant cell wall biology [2, 4]. The reaction is conserved across kingdoms, from mammals to plants and even diatoms, highlighting its fundamental importance.
peptidyl-proline hydroxylation to 4-hydroxy-L-proline At A Glance
| GO ID | GO:0018401 |
|---|---|
| GO term | peptidyl-proline hydroxylation to 4-hydroxy-L-proline |
| Ontology | biological_process |
| Synonym | none |
| Major function | Post-translational modification of proline residues to 4-hydroxy-L-proline, essential for collagen stability and plant cell wall structure |
| Catalytic enzyme | Procollagen-proline,2-oxoglutarate-4-dioxygenase (prolyl 4-hydroxylase) |
| Cofactors | 2-oxoglutarate, iron, ascorbate |
| Substrates | Peptidyl-proline in collagen-like sequences |
| Conservation | Found in animals, plants, and bacteria |
What Is GO:0018401?
GO:0018401 is defined as the modification of peptidyl-proline to form 4-hydroxy-L-proline, catalyzed by procollagen-proline,2-oxoglutarate-4-dioxygenase. This enzymatic reaction adds a hydroxyl group to the proline ring, typically at the 4-position, and requires 2-oxoglutarate, iron, and ascorbate as cofactors [6, 7].
Why Is peptidyl-proline hydroxylation to 4-hydroxy-L-proline Important in Cell Biology?
Peptidyl-proline hydroxylation to 4-hydroxy-L-proline is crucial for the structural integrity of collagen, the most abundant protein in mammals. Without this modification, collagen triple helices are unstable, leading to connective tissue disorders. The reaction also plays roles in plant root hair expansion and cell wall formation, and in bacterial pathogenesis [2, 3]. Understanding this process provides insights into fibrosis, cancer, and developmental biology, and offers targets for therapeutic intervention.
• Essential for collagen triple-helix stability and extracellular matrix integrity.
• Required for normal plant root hair expansion and cell wall structure.
• Involved in bacterial modification of collagen-like substrates, impacting host-pathogen interactions.
• Dysregulation contributes to fibrotic diseases such as liver and lung fibrosis.
• Potential target for anti-cancer therapies, as prolyl 4-hydroxylase is overexpressed in some tumors.
• Conserved across species, enabling comparative studies in plants, diatoms, and mammals [4, 8].
• Serves as a model for studying 2-oxoglutarate-dependent dioxygenases.
• Impacts tissue culture systems, such as fibroblast collagen production.
• Regulated by oxygen and iron availability, linking to hypoxia and metabolism.
• Inhibitors like 3,4-dehydroproline selectively block the reaction, providing research tools.
What Happens During peptidyl-proline hydroxylation to 4-hydroxy-L-proline?
Substrate Recognition and Binding
In simple terms: The enzyme finds and grabs onto a proline residue in a peptide chain.
Prolyl 4-hydroxylase recognizes peptidyl-proline sequences, often in X-Pro-Gly repeats typical of collagen. The enzyme binds the substrate with the proline residue positioned for hydroxylation. Bacterial enzymes can modify collagen-like substrates in asymmetric patterns, indicating specific recognition motifs.
Catalytic Hydroxylation
In simple terms: The enzyme adds an oxygen atom to proline, turning it into hydroxyproline.
The hydroxylation reaction uses 2-oxoglutarate as a co-substrate, which is decarboxylated to succinate, while the proline residue is hydroxylated. This reaction requires iron and ascorbate. The catalytic mechanism does not require protein disulphide-isomerase activity.
Cofactor Requirements and Decarboxylation
In simple terms: The enzyme needs helper molecules like iron and vitamin C to work.
Prolyl hydroxylase requires ferrous iron, 2-oxoglutarate, and ascorbate for activity. The enzyme can decarboxylate 2-oxoglutarate even in the absence of peptidyl proline, a half-reaction that highlights the uncoupled cycle. Ascorbate maintains iron in its reduced state.
Post-Hydroxylation Processing
In simple terms: After modification, the protein can fold into its final shape.
Hydroxyproline residues stabilize the collagen triple helix through hydrogen bonding. In plants, hydroxyproline-rich glycoproteins contribute to cell wall integrity and root hair expansion. In diatoms, hydroxyproline and dihydroxyproline are formed during silica shell formation.
Key Genes Involved in GO:0018401 peptidyl-proline hydroxylation to 4-hydroxy-L-proline
The following genes and proteins are involved in peptidyl-proline hydroxylation to 4-hydroxy-L-proline, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| P4HA1 | Prolyl 4-hydroxylase alpha subunit 1 | Catalyzes proline hydroxylation in collagen; studied in fibrosis and cancer |
| P4HA2 | Prolyl 4-hydroxylase alpha subunit 2 | Isoform with distinct tissue distribution; involved in extracellular matrix remodeling |
| P4HA3 | Prolyl 4-hydroxylase alpha subunit 3 | Less characterized; potential role in development |
| P4HB | Protein disulfide isomerase, beta subunit | Beta subunit of prolyl 4-hydroxylase; maintains enzyme solubility |
| P4H1 | Plant prolyl 4-hydroxylase | Regulates root hair expansion in Arabidopsis |
| P4H2 | Plant prolyl 4-hydroxylase | Isoform involved in cell wall glycoprotein modification |
| P4H3 | Plant prolyl 4-hydroxylase | Contributes to root hair growth |
| P4H4 | Plant prolyl 4-hydroxylase | Expressed in specific tissues; role in development |
| P4H5 | Plant prolyl 4-hydroxylase | May modify extensin proteins |
| P4H6 | Plant prolyl 4-hydroxylase | Involved in stress responses |
| P4H7 | Plant prolyl 4-hydroxylase | Potential role in cell elongation |
| P4H8 | Plant prolyl 4-hydroxylase | Expressed in roots; affects hair expansion |
| P4H9 | Plant prolyl 4-hydroxylase | Regulates cell wall structure |
| P4H10 | Plant prolyl 4-hydroxylase | Isoform with unknown function |
| P4H11 | Plant prolyl 4-hydroxylase | May be involved in root hair development |
| Bacillus anthracis P4H | Bacterial prolyl 4-hydroxylase | Modifies collagen-like substrates; studied for host-pathogen interactions |
| Nitzschia angularis P4H | Diatom prolyl 4-hydroxylase | Forms hydroxyproline during silica shell formation |
How Is peptidyl-proline hydroxylation to 4-hydroxy-L-proline Regulated?
Peptidyl-proline hydroxylation is regulated by oxygen availability, iron levels, and ascorbate, as the enzyme requires these cofactors [6, 7]. In plants, prolyl 4-hydroxylase activity is regulated by developmental cues and environmental factors, impacting root hair expansion. In mammals, expression of prolyl 4-hydroxylase subunits is induced by hypoxia and growth factors, linking to fibrosis and cancer.
peptidyl-proline hydroxylation to 4-hydroxy-L-proline and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| P4HA1 | Fibrosis, cancer | Knockout mice, cancer cell lines |
| P4HA2 | Extracellular matrix remodeling | Overexpression in fibroblasts |
| P4HB | Connective tissue disorders | Point mutation in patient cells |
| Plant P4H | Root hair expansion defects | Arabidopsis knockout lines |
| Bacillus anthracis P4H | Host-pathogen interaction | Bacterial infection models |
Fibrotic Diseases
Overexpression of prolyl 4-hydroxylase leads to excessive collagen deposition, contributing to liver and lung fibrosis. Inhibitors of the enzyme are being explored as anti-fibrotic therapies.
Cancer
Prolyl 4-hydroxylase is upregulated in various cancers, promoting tumor stroma formation and metastasis. Targeting this enzyme may disrupt tumor microenvironment.
Connective Tissue Disorders
Defects in proline hydroxylation cause collagen instability, leading to conditions like Ehlers-Danlos syndrome and osteogenesis imperfecta.
Plant Development
In plants, impaired prolyl 4-hydroxylation affects root hair expansion and cell wall integrity, impacting nutrient uptake.
From peptidyl-proline hydroxylation to 4-hydroxy-L-proline-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of P4HA1 in collagen stability? | P4HA1 knockout cell line |
| How does a point mutation in P4HA2 affect enzyme activity? | Point-mutation knock-in in HEK293 cells |
| Can prolyl 4-hydroxylase be tagged for imaging? | Knock-in of fluorescent tag |
| What happens when P4HA3 is overexpressed? | Overexpression in fibroblasts |
| Which genes regulate root hair expansion? | Plant P4H knockout lines |
| How does bacterial P4H modify collagen? | Recombinant enzyme assays |
How to Study the peptidyl-proline hydroxylation to 4-hydroxy-L-proline Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzymatic assay | Hydroxylation activity | Inhibitor screening |
| Mass spectrometry | Hydroxyproline content | Collagen analysis |
| RNA-seq | Gene expression | Transcriptional regulation |
| Western blot | Protein levels | Enzyme expression |
| Immunohistochemistry | Tissue localization | Fibrosis studies |
| CRISPR knockout | Gene function | Loss-of-function studies |
| Overexpression | Gain-of-function | Cancer models |
Enzymatic Assays
Prolyl 4-hydroxylase activity can be measured using radioactive or fluorescent substrates, monitoring the decarboxylation of 2-oxoglutarate.
Mass Spectrometry
Mass spectrometry detects hydroxyproline residues in collagen or other proteins, providing quantitative data on hydroxylation levels.
Gene Expression Analysis
RNA-seq and qPCR measure expression of P4H genes under different conditions, such as hypoxia or fibrosis.
Imaging
Fluorescent tagging of prolyl 4-hydroxylase allows visualization of its subcellular localization and dynamics.
How CRISPR Can Be Used to Study GO:0018401 peptidyl-proline hydroxylation to 4-hydroxy-L-proline
Knockout
CRISPR knockout of P4HA genes eliminates prolyl 4-hydroxylase activity, revealing its role in collagen stability and cell growth.
Point Mutation
Introducing point mutations in the catalytic domain of P4HA1 can mimic patient mutations, helping to understand enzyme dysfunction.
Knock-in
Knock-in of tagged P4HA1 allows live-cell imaging and proteomic analysis of the enzyme.
Overexpression
Overexpression of P4HA2 in cancer cell lines promotes collagen deposition and tumor growth, modeling fibrosis and cancer.
How EDITGENE Supports peptidyl-proline hydroxylation to 4-hydroxy-L-proline Research
Researchers studying peptidyl-proline hydroxylation to 4-hydroxy-L-proline-related genes often need to determine whether a candidate gene is causally involved in collagen modification, fibrosis, or plant development. EDITGENE provides comprehensive CRISPR services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for peptidyl-proline hydroxylation to 4-hydroxy-L-proline research.
Frequently Asked Questions About peptidyl-proline hydroxylation to 4-hydroxy-L-proline
What is peptidyl-proline hydroxylation to 4-hydroxy-L-proline?
It is a post-translational modification where proline residues in proteins are converted to 4-hydroxy-L-proline, catalyzed by prolyl 4-hydroxylase [1, 5].
What genes are involved in peptidyl-proline hydroxylation?
Key genes include P4HA1, P4HA2, P4HA3, and P4HB in humans, and multiple P4H genes in plants [2, 5].
What is the GO ID for peptidyl-proline hydroxylation to 4-hydroxy-L-proline?
The GO ID is GO:0018401.
Why is proline hydroxylation important for collagen?
Hydroxyproline stabilizes the collagen triple helix through hydrogen bonding, essential for connective tissue strength.
Which enzyme catalyzes peptidyl-proline hydroxylation?
Procollagen-proline,2-oxoglutarate-4-dioxygenase (prolyl 4-hydroxylase) catalyzes the reaction.
What cofactors are required for prolyl 4-hydroxylase?
The enzyme requires 2-oxoglutarate, iron, and ascorbate [6, 7].
How is peptidyl-proline hydroxylation studied?
Methods include enzymatic assays, mass spectrometry, RNA-seq, and CRISPR knockout models [3, 5].
What diseases are linked to defects in proline hydroxylation?
Fibrosis, cancer, and connective tissue disorders like Ehlers-Danlos syndrome [5, 7].
Can CRISPR be used to study prolyl 4-hydroxylase genes?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are available.
What is the role of prolyl 4-hydroxylase in plants?
It regulates root hair expansion and cell wall integrity.
Conclusion
Peptidyl-proline hydroxylation to 4-hydroxy-L-proline (GO:0018401) is a fundamental post-translational modification with critical roles in collagen stability, plant development, and disease. Understanding its mechanisms and regulation offers insights into fibrosis, cancer, and connective tissue disorders. EDITGENE provides advanced CRISPR tools to study this pathway and accelerate therapeutic development.
References
- 1. Cooper JB et al.. 1983. Selective inhibition of proline hydroxylation by 3,4-dehydroproline.. Plant Physiol 73(2):324-8 PMID: 16663215
- 2. Velasquez SM et al.. 2015. Complex regulation of prolyl-4-hydroxylases impacts root hair expansion.. Mol Plant 8(5):734-46 PMID: 25655826
- 3. Schnicker NJ et al.. 2016. Bacillus anthracis Prolyl 4-Hydroxylase Modifies Collagen-like Substrates in Asymmetric Patterns.. J Biol Chem 291(25):13360-74 PMID: 27129244
- 4. Schmidt A et al.. 1991. Peptidyl proline hydroxylation and the growth of a soybean cell culture.. Plant Physiol 96(2):656-9 PMID: 16668236
- 5. Gribble TJ et al.. 1969. Collagen chain formation and peptidyl proline hydroxylation in monolayer tissue cultures of L-929 fibroblasts.. Arch Biochem Biophys 129(1):308-16 PMID: 5762970
- 6. Counts DF et al.. 1978. Prolyl hydroxylase half reaction: peptidyl prolyl-independent decarboxylation of alpha-ketoglutarate.. Proc Natl Acad Sci U S A 75(5):2145-9 PMID: 209453
- 7. Myllylä R et al.. 1989. The catalytic mechanism of the hydroxylation reaction of peptidyl proline and lysine does not require protein disulphide-isomerase activity.. Biochem J 263(2):609-11 PMID: 2557001
- 8. Sadava D et al.. 1977. Studies on the biochemistry and fine structure of silica shell formation in diatoms : Formation of hydroxyproline and dihydroxyproline in Nitzschia angularis.. Planta 135(1):7-11 PMID: 24419885
