GO:0000413 protein peptidyl-prolyl isomerization: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0000413 describes the cis-trans isomerization of proline residues in proteins, a conformational switch that regulates protein function, stability, and interactions.
• Peptidyl-prolyl isomerases (PPIases) such as Pin1, cyclophilins, and FK506-binding proteins catalyze this slow isomerization step.
• Proline isomerization acts as a molecular timer in signaling, affecting kinase activity, protein degradation, and gene expression.
• Dysregulation of PPIases is linked to cancer, neurodegeneration, and immune disorders, making them therapeutic targets.
• CRISPR-based knockout, point mutation, and knock-in models enable precise dissection of PPIase function in disease and development.
• Studying GO:0000413 requires integrated methods such as proteomics, isomer-specific antibodies, and CRISPR screening.
Description
Protein peptidyl-prolyl isomerization (GO:0000413) is a post-translational modification that catalyzes the slow cis-trans isomerization of proline imidic peptide bonds, a rate-limiting step in protein folding and conformational switching. This process is essential for many cellular functions, as proline isomerization can dramatically alter protein structure and activity, acting as a molecular switch in signal transduction. Peptidyl-prolyl isomerases (PPIases) are the enzymes responsible for this modification, and they are highly conserved across eukaryotes and prokaryotes. Researchers study GO:0000413 because it impacts diverse biological processes, from cell cycle regulation to immune response, and its dysregulation is implicated in cancer and neurodegenerative diseases. Understanding the mechanisms and regulation of protein peptidyl-prolyl isomerization provides insights into fundamental cell biology and offers potential therapeutic targets.
protein peptidyl-prolyl isomerization At A Glance
| GO ID | GO:0000413 |
|---|---|
| GO term | protein peptidyl-prolyl isomerization |
| Ontology | biological_process |
| Synonym | protein proline isomerization |
| Definition | The modification of a protein by cis-trans isomerization of a proline residue. |
| Major function | Catalysis of cis-trans isomerization of proline imidic peptide bonds, affecting protein conformation and function. |
| Enzymes involved | Peptidyl-prolyl isomerases (PPIases) including Pin1, cyclophilins, FKBP family members. |
| Subcellular location | Cytoplasm, nucleus, mitochondria, and other compartments depending on the PPIase. |
| Related diseases | Cancer, Alzheimer's disease, immune disorders. |
What Is GO:0000413?
GO:0000413, protein peptidyl-prolyl isomerization, is defined as the modification of a protein by cis-trans isomerization of a proline residue. This process involves the rotation of the peptide bond preceding a proline, which can exist in either cis or trans conformation. The isomerization is catalyzed by enzymes known as peptidyl-prolyl isomerases (PPIases), which accelerate the interconversion between these two states, thereby influencing protein folding, stability, and function.
Why Is protein peptidyl-prolyl isomerization Important in Cell Biology?
Protein peptidyl-prolyl isomerization is a critical regulatory mechanism because proline isomerization can act as a molecular switch that controls protein activity, interactions, and degradation. This process is involved in many cellular pathways, including cell cycle progression, signal transduction, and immune responses. Dysregulation of PPIases has been linked to various human diseases, such as cancer and neurodegeneration, making them attractive targets for therapeutic intervention. Therefore, understanding GO:0000413 is essential for both basic research and drug development.
• Regulates protein function by inducing conformational changes.
• Controls the stability and degradation of key regulatory proteins.
• Modulates kinase signaling pathways, including those driven by Pin1.
• Influences immune responses through cyclophilin and FKBP family members.
• Implicated in cancer progression and stem cell maintenance.
• Linked to neurodegenerative diseases such as Alzheimer's.
• Provides targets for immunosuppressive drugs like cyclosporine and FK506.
• Essential for plant development and hormone signaling.
• Plays a role in bacterial virulence and stress responses.
• Enables precise control of protein folding in biotechnology applications.
What Happens During protein peptidyl-prolyl isomerization?
Substrate recognition and binding
In simple terms: The enzyme grabs onto the target protein at a specific proline-containing sequence.
Peptidyl-prolyl isomerases (PPIases) recognize substrate proteins through specific binding pockets that accommodate proline residues in the context of a peptide bond. For example, Pin1 binds to phosphorylated Ser/Thr-Pro motifs, ensuring specificity for its substrates. Cyclophilins and FKBPs also exhibit distinct substrate preferences, often mediated by additional domains that confer target selectivity. This recognition step is crucial for the subsequent isomerization reaction.
Catalysis of cis-trans isomerization
In simple terms: The enzyme twists the proline bond, flipping it between two shapes.
Once bound, the PPIase catalyzes the rotation of the peptide bond preceding the proline, facilitating the interconversion between cis and trans conformations. This process involves a conserved catalytic mechanism that lowers the energy barrier for isomerization. The reaction is reversible, and the equilibrium can be shifted depending on the enzyme and substrate. For instance, SlyD, a bacterial PPIase, accelerates trans-to-cis isomerization under mechanical load.
Conformational change and functional consequences
In simple terms: The shape change alters how the protein behaves, like a switch turning on or off.
The isomerization event induces a conformational change in the substrate protein, which can affect its activity, interactions, or stability. For example, Pin1-mediated isomerization of phosphorylated proteins can regulate their phosphorylation status, ubiquitination, and degradation. In rice, peptidyl-prolyl isomerization targets Aux/IAA proteins for proteasomal degradation during auxin signaling. Thus, this step translates the isomerization into diverse cellular outcomes.
Regulation and feedback
In simple terms: The process is controlled by other molecules and can be adjusted as needed.
PPIase activity is regulated at multiple levels, including post-translational modifications, subcellular localization, and interaction with inhibitors. For instance, Pin1 is stabilized by USP34, which promotes its function in glioma stem cells. Additionally, natural inhibitors such as cyclosporine and FK506 can block specific PPIases, providing a means for pharmacological intervention. This regulation ensures that isomerization is tightly controlled in response to cellular signals.
Key Genes Involved in GO:0000413 protein peptidyl-prolyl isomerization
The following genes encode key peptidyl-prolyl isomerases and related proteins that catalyze or regulate protein peptidyl-prolyl isomerization (GO:0000413).
| Gene | Major Role | Research Relevance |
|---|---|---|
| PIN1 | Phospho-Ser/Thr-Pro isomerase | Regulates cell cycle, cancer, neurodegeneration |
| PPIA | Cyclophilin A, isomerase | Immune suppression, viral infection |
| PPIB | Cyclophilin B, isomerase | Collagen folding, ER function |
| PPIC | Cyclophilin C, isomerase | Unknown, potential role in stress |
| PPID | Cyclophilin D, isomerase | Mitochondrial permeability transition |
| PPIE | Cyclophilin E, isomerase | RNA splicing regulation |
| PPIF | Cyclophilin F, isomerase | Mitochondrial function |
| PPIG | Cyclophilin G, isomerase | Pre-mRNA splicing |
| PPIH | Cyclophilin H, isomerase | Spliceosome component |
| PPIL1 | Cyclophilin-like, isomerase | Spliceosome, cancer |
| FKBP1A | FK506-binding protein 1A | Immunosuppression, TGF-beta signaling |
| FKBP5 | FK506-binding protein 5 | Stress response, psychiatric disorders |
| FKBP12 | FK506-binding protein 12 | mTOR regulation, immunosuppression |
| SlyD | Bacterial PPIase | Mechanosignaling, virulence |
| CYP1 | Cyclophilin from Pyropia yezoensis | Recombinant protein activity |
| USP34 | Deubiquitinase stabilizing Pin1 | Glioma stem cells |
| UBC9 | SUMO-conjugating enzyme | Isomerization target of Pin1 |
How Is protein peptidyl-prolyl isomerization Regulated?
Protein peptidyl-prolyl isomerization is regulated by various mechanisms, including the expression levels and post-translational modifications of PPIases. For example, Pin1 is stabilized by the deubiquitinase USP34, which promotes Ubc9 isomerization and protein sumoylation in glioma stem cells. Additionally, PPIase activity can be modulated by phosphorylation, subcellular localization, and interaction with inhibitors such as cyclosporine and FK506. The process is also influenced by cellular stress and signaling pathways, ensuring dynamic control of protein function.
protein peptidyl-prolyl isomerization and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PIN1 | Cancer, Alzheimer's disease | Knockout mice, patient-derived organoids |
| PPIA | Immune disorders, viral infection | CRISPR knockout cell lines |
| FKBP5 | Psychiatric disorders, stress response | Point mutation knock-in mice |
| USP34 | Glioma | Overexpression in glioma stem cells |
| UBC9 | Cancer, sumoylation defects | Knock-in of isomerization-deficient mutant |
Cancer
Dysregulation of peptidyl-prolyl isomerization is implicated in multiple cancers. Pin1 is often overexpressed in breast, prostate, and brain tumors, where it promotes oncogenic signaling by isomerizing phosphorylated proteins. In glioma stem cells, USP34-mediated stabilization of Pin1 enhances Ubc9 isomerization and sumoylation, supporting tumor growth. Targeting PPIases with inhibitors has shown promise in preclinical studies, making them attractive therapeutic targets.
Neurodegenerative diseases
Pin1 plays a protective role in neurons by isomerizing phosphorylated tau and amyloid precursor protein, and its dysfunction is linked to Alzheimer's disease. Loss of Pin1 activity leads to tau hyperphosphorylation and aggregation, contributing to neurodegeneration. Modulating PPIase activity could offer therapeutic strategies for such diseases.
Immune disorders
Cyclophilins and FKBPs are targets of immunosuppressive drugs like cyclosporine and FK506, which inhibit their isomerase activity to suppress T-cell activation. This highlights the critical role of peptidyl-prolyl isomerization in immune regulation and transplantation medicine.
From protein peptidyl-prolyl isomerization-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of PIN1 affect tumor growth? | PIN1 knockout cell lines and mouse xenografts |
| How does a specific proline mutation alter protein function? | Point mutation knock-in via CRISPR |
| Can PPIase inhibitors block cancer stem cell self-renewal? | Overexpression of PPIase in stem cells with inhibitor treatment |
| What is the role of Pin1 in neurodegeneration? | Knock-in of phospho-deficient tau mutants |
| How does SlyD contribute to bacterial virulence? | SlyD knockout bacteria and infection models |
| Does cyclophilin A isomerization regulate immune response? | PPIA knockout mice and T-cell assays |
How to Study the protein peptidyl-prolyl isomerization Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Mass spectrometry | Cis-trans isomerization states | Proteome-wide identification of isomerization targets |
| Isomer-specific antibodies | Conformational change of specific proteins | Western blot, immunofluorescence |
| CRISPR knockout screens | Gene essentiality and drug sensitivity | Identifying regulators of isomerization |
| Enzyme activity assays | PPIase catalytic activity | Inhibitor screening, kinetic studies |
| NMR spectroscopy | Protein dynamics and isomerization | Structural characterization of PPIase-substrate complexes |
| X-ray crystallography | 3D structure of PPIases | Rational drug design |
| RNA-seq | Transcriptional changes upon PPIase modulation | Pathway analysis in knockout models |
Proteomics and isomer-specific detection
Mass spectrometry-based proteomics can identify proteins undergoing peptidyl-prolyl isomerization by detecting cis-trans conformational changes. Isomer-specific antibodies are also used to monitor the isomerization state of specific proteins in cells.
CRISPR screening
Genome-wide CRISPR knockout screens can identify genes that modulate sensitivity to PPIase inhibitors or regulate isomerization-dependent pathways. This approach helps uncover novel components of GO:0000413.
Biochemical assays
In vitro isomerase assays using synthetic peptides or recombinant proteins measure PPIase activity. These assays are essential for characterizing enzyme kinetics and testing inhibitors.
Structural biology
X-ray crystallography and NMR spectroscopy provide atomic-level insights into how PPIases catalyze isomerization and how substrates bind. Such studies inform drug design targeting PPIases.
How CRISPR Can Be Used to Study GO:0000413 protein peptidyl-prolyl isomerization
Knockout
CRISPR knockout of PPIase genes such as PIN1 or PPIA allows researchers to study loss-of-function phenotypes, including effects on cell cycle, apoptosis, and tumor growth. Knockout cell lines are valuable for validating drug targets and understanding disease mechanisms.
Point Mutation
Introducing point mutations in the catalytic domain of PPIases via CRISPR can dissect the importance of specific residues for isomerase activity. For example, mutating the catalytic cysteine in Pin1 abolishes its isomerase function, helping distinguish isomerase-dependent from independent roles.
Knock-in
Knock-in of disease-associated mutations, such as those in tau that affect Pin1 binding, can model neurodegenerative diseases. CRISPR knock-in mice or cell lines carrying these mutations provide insights into pathogenesis.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of PPIases like Pin1 can mimic overexpression observed in cancers. Such models are used to study oncogenic signaling and test targeted therapies.
How EDITGENE Supports protein peptidyl-prolyl isomerization Research
Researchers studying protein peptidyl-prolyl isomerization-related genes often need to determine whether a candidate gene is causally involved in a specific cellular process or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to enable precise genetic manipulation and functional interrogation of these genes.
Contact EDITGENE today to design your custom CRISPR model for protein peptidyl-prolyl isomerization research.
Frequently Asked Questions About protein peptidyl-prolyl isomerization
What is protein peptidyl-prolyl isomerization?
It is the cis-trans isomerization of proline residues in proteins, catalyzed by PPIases, which regulates protein conformation and function.
What genes are involved in protein peptidyl-prolyl isomerization?
Key genes include PIN1, PPIA, PPIB, FKBP1A, and others encoding peptidyl-prolyl isomerases.
How does Pin1 regulate protein function?
Pin1 binds to phosphorylated Ser/Thr-Pro motifs and catalyzes isomerization, altering protein stability, interactions, and activity.
What diseases are linked to peptidyl-prolyl isomerization?
Cancer, Alzheimer's disease, and immune disorders are associated with dysregulated PPIases.
Can CRISPR be used to study PPIases?
Yes, CRISPR knockout, point mutation, and knock-in models enable precise functional studies of PPIases.
What are PPIase inhibitors?
Compounds like cyclosporine and FK506 inhibit specific PPIases and are used as immunosuppressants.
How is peptidyl-prolyl isomerization detected?
Methods include mass spectrometry, isomer-specific antibodies, and enzyme activity assays.
What is the role of cyclophilins in immunity?
Cyclophilins regulate T-cell activation and are targets of immunosuppressive drugs.
Is peptidyl-prolyl isomerization reversible?
Yes, the isomerization is reversible, and the equilibrium can be shifted by PPIases.
What model systems are used to study GO:0000413?
Cell lines, knockout mice, and CRISPR-engineered models are commonly used.
Conclusion
Protein peptidyl-prolyl isomerization (GO:0000413) is a fundamental post-translational modification that controls protein conformation and function through the action of PPIases. Its dysregulation contributes to cancer, neurodegeneration, and immune disorders, making it a compelling area of research. Advances in CRISPR technology and biochemical assays continue to unravel the complexities of this process, offering new opportunities for therapeutic intervention.
References
- 1. Chen XR et al.. 2023. Regulation of eukaryotic protein kinases by Pin1, a peptidyl-prolyl isomerase.. Adv Biol Regul 87:100938 PMID: 36496344
- 2. Wang XJ et al.. 2006. Peptidyl-prolyl isomerase inhibitors.. Biopolymers 84(2):125-46 PMID: 16302169
- 3. Ulagesan S et al.. 2020. Peptidyl-prolyl isomerase and the biological activities of recombinant protein cyclophilin from Pyropia yezoensis (PyCyp).. Protein Expr Purif 172:105636 PMID: 32272150
- 4. Zhu Q et al.. 2024. Stabilization of Pin1 by USP34 promotes Ubc9 isomerization and protein sumoylation in glioma stem cells.. Nat Commun 15(1):40 PMID: 38167292
- 5. Schiene-Fischer C. 2015. Multidomain Peptidyl Prolyl cis/trans Isomerases.. Biochim Biophys Acta 1850(10):2005-16 PMID: 25445709
- 7. Sengupta A et al.. 2021. SlyD Accelerates trans-to-cis Prolyl Isomerization in a Mechanosignaling Protein under Load.. J Phys Chem B 125(31):8712-8721 PMID: 34279937
- 8. Jing H et al.. 2015. Peptidyl-prolyl isomerization targets rice Aux/IAAs for proteasomal degradation during auxin signalling.. Nat Commun 6:7395 PMID: 26096057
