GO:0009368 endopeptidase Clp complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0009368 (endopeptidase Clp complex) is a cellular_component term describing a protein complex built from ClpX, ClpC, ClpD, ClpP or ClpR family members, in which ClpP forms the proteolytic core and ClpA/ClpX act as regulatory subunits.
• Clp complexes are ATP-dependent proteases that unfold and degrade damaged or regulatory proteins, and both enzymatically active and inactive assemblies can form.
• In mitochondria, the CLPP/CLPX complex is a validated anticancer target, and small-molecule ClpP agonists such as TR-107 selectively kill cancer cells by disrupting mitochondrial metabolism.
• In bacteria, Clp complexes control dormancy depth, antibiotic tolerance and metal-stress adaptation, making them attractive antibacterial targets.
• The mitochondrial disaggregase CLPB cooperates with the Clp system to maintain mitochondrial calcium signalling and dynamics.
• CRISPR knockout, point-mutation, knock-in and overexpression models are essential to dissect Clp subunit function in cancer, infection and mitochondrial disease.
Description
The endopeptidase Clp complex (GO:0009368) is a conserved ATP-dependent protease machine found in bacteria, plants and mitochondria. According to the QuickGO definition, it is a protein complex comprised of members of the ClpX, ClpC, ClpD, ClpP or ClpR protein families, in which ClpPs are the proteolytic subunit of active complexes and ClpA and ClpX form the regulatory subunits; enzymatically active and inactive complexes can form. This architecture allows the complex to combine substrate recognition, ATP-driven unfolding and processive proteolysis within a single assembly. Researchers study GO:0009368 because it sits at the intersection of protein quality control, mitochondrial biology and microbial pathogenesis. In mitochondria, the CLPP/CLPX complex is required for the mitochondrial unfolded protein response and is a druggable vulnerability in acute myeloid leukaemia and other cancers. In bacteria, Clp complexes regulate dormancy depth and antibiotic tolerance, and they are activated by acyldepsipeptides that accelerate proteolysis. In Staphylococcus aureus, Clp activity is coordinated with metal sequestration during infection. Because Clp complexes can exist in active and inactive states, their composition and assembly state directly determine cellular outcomes. This makes GO:0009368 a high-value annotation for functional genomics, structural biology and drug discovery, and it explains why CRISPR-based models of Clp subunits are increasingly used to link genotype to proteolytic phenotype.
endopeptidase Clp complex At A Glance
| GO ID | GO:0009368 |
|---|---|
| GO term | endopeptidase Clp complex |
| Ontology | cellular_component |
| Synonym | none |
| Major function | ATP-dependent proteolysis of damaged or regulatory proteins |
| Subunit families | ClpX, ClpC, ClpD, ClpP, ClpR |
| Catalytic core | ClpP (and ClpR in plants) |
| Regulatory subunits | ClpA, ClpX |
| Activity states | Enzymatically active and inactive complexes can form |
What Is GO:0009368?
GO:0009368 describes a protein complex whose subunits belong to the ClpX, ClpC, ClpD, ClpP or ClpR families. ClpP proteins form the proteolytic core, while ClpA and ClpX function as regulatory subunits that recognize, unfold and translocate substrates into the core. The complex can assemble into enzymatically active or inactive forms, and its activity depends on ATP and on the specific subunit composition.
Why Is endopeptidase Clp complex Important in Cell Biology?
GO:0009368 is important because Clp complexes are central hubs of protein quality control and are directly linked to cancer cell lethality, bacterial dormancy and antibiotic tolerance, mitochondrial stress signalling and metal-stress adaptation. Understanding their composition and regulation provides a mechanistic basis for developing ClpP agonists, antibacterial acyldepsipeptides and mitochondrial-targeted therapeutics.
• Mitochondrial ClpP is a validated anticancer target; its activation induces selective cancer cell lethality.
• ClpP agonists such as TR-107 disrupt mitochondrial metabolism and inhibit colorectal cancer cell growth.
• Bacterial Clp complexes regulate dormancy depth and are critical for antibiotic tolerance.
• Acyldepsipeptides stimulate the Streptomyces Clp-ATPase/ClpP complex, providing a paradigm for antibiotic development.
• Staphylococcus aureus coordinates Clp activity with calprotectin-dependent metal sequestration during infection.
• The mitochondrial disaggregase CLPB functionally interacts with the Clp system to maintain calcium signalling and dynamics.
• ATF4 is a key regulator of the mitochondrial stress response that involves ClpP-dependent proteolysis.
• Clp complexes are conserved from bacteria to humans, enabling cross-species mechanistic studies.
• Both active and inactive Clp assemblies exist, making assembly state a key experimental variable.
What Happens During endopeptidase Clp complex?
Substrate recognition and ATP-dependent unfolding
In simple terms: The Clp machine first grabs a target protein and uses ATP energy to pull it apart.
Regulatory subunits such as ClpA and ClpX recognize specific substrate motifs and use ATP hydrolysis to unfold and translocate the substrate into the proteolytic chamber. In mitochondria, CLPX performs this function for the CLPP core.
Proteolysis inside the ClpP chamber
In simple terms: Once inside, the protein is chopped into small pieces by the ClpP core.
ClpP subunits form a barrel-shaped proteolytic chamber with active sites that degrade translocated polypeptides processively. ClpR proteins in plants are homologous but catalytically inactive subunits that can modulate complex activity.
Assembly of active and inactive complexes
In simple terms: The same parts can assemble into working or non-working versions of the machine.
The QuickGO definition states that enzymatically active and inactive complexes can form. This reflects the ability of ClpP to assemble with different regulatory subunits or in different oligomeric states, which determines whether proteolysis occurs.
Physiological outputs: stress response and dormancy
In simple terms: The Clp machine helps cells survive stress by cleaning up proteins and controlling dormancy.
In bacteria, Clp-dependent proteolysis regulates dormancy depth and antibiotic tolerance. In mitochondria, ClpP activation triggers the mitochondrial unfolded protein response and can induce selective cancer cell death.
Key Genes Involved in GO:0009368 endopeptidase Clp complex
The following genes encode the major subunits and regulators of the endopeptidase Clp complex across species.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CLPP | Proteolytic core subunit in mitochondria | Anticancer target; activated by ClpP agonists |
| CLPX | Mitochondrial regulatory ATPase subunit | Substrate recognition and unfolding |
| CLPC | Bacterial/plant regulatory ATPase | Stress response and proteolysis |
| CLPD | Plant chloroplast regulatory ATPase | Chloroplast protein quality control |
| CLPR | Plant catalytically inactive ClpP homolog | Modulates complex activity |
| CLPA | Bacterial regulatory ATPase | Substrate delivery to ClpP |
| CLPB | Mitochondrial disaggregase | Calcium signalling and dynamics |
| ATF4 | Transcription factor in mitochondrial stress response | Regulates ClpP-dependent stress signalling |
| clpP (bacterial) | Proteolytic core in bacteria | Dormancy and antibiotic tolerance |
| clpX (bacterial) | Regulatory ATPase in bacteria | Dormancy and antibiotic tolerance |
| clpC (S. aureus) | Regulatory ATPase | Metal sequestration adaptation |
| clpP (S. aureus) | Proteolytic core | Metal sequestration adaptation |
| clpA (Streptomyces) | Regulatory ATPase | Acyldepsipeptide activation |
| clpP (Streptomyces) | Proteolytic core | Acyldepsipeptide activation |
| CLPP (human) | Mitochondrial proteolytic core | Cancer cell lethality |
| CLPX (human) | Mitochondrial regulatory ATPase | Mitochondrial proteostasis |
| CLPB (human) | Mitochondrial disaggregase | Calcium signalling and dynamics |
How Is endopeptidase Clp complex Regulated?
Clp complex activity is regulated at multiple levels. In mitochondria, the transcription factor ATF4 controls a stress response that includes ClpP-dependent proteolysis. Small molecules such as acyldepsipeptides can directly bind and dysregulate ClpP, converting it into an uncontrolled protease. In bacteria, Clp activity is coordinated with metal availability during infection. The assembly state of the complex, including active versus inactive forms, is itself a regulatory mechanism.
endopeptidase Clp complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CLPP | Cancer (leukaemia, colorectal) | CLPP knockout and point-mutation cell lines |
| CLPX | Mitochondrial proteostasis | CLPX knockout and tagged knock-in |
| CLPB | Mitochondrial calcium signalling | CLPB knockout and overexpression |
| clpP (bacterial) | Antibiotic tolerance | Bacterial clpP deletion strains |
| clpC (S. aureus) | Metal sequestration adaptation | S. aureus clpC mutant |
Cancer
Mitochondrial ClpP is overexpressed in several cancers, and its activation by small molecules such as TR-107 induces selective cancer cell lethality by disrupting mitochondrial metabolism. This makes ClpP a promising anticancer target.
Bacterial infection and antibiotic tolerance
Bacterial Clp complexes regulate dormancy depth and antibiotic tolerance, and they are activated by acyldepsipeptides that accelerate proteolysis. Staphylococcus aureus coordinates Clp activity with metal sequestration during infection.
Mitochondrial stress and calcium signalling
The mitochondrial disaggregase CLPB functionally interacts with the Clp system to maintain calcium signalling and dynamics, linking Clp biology to mitochondrial physiology. ATF4 is a key regulator of the mitochondrial stress response that involves ClpP.
From endopeptidase Clp complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does CLPP loss affect cancer cell viability? | CLPP knockout cell lines |
| Does a specific CLPP mutation alter proteolytic activity? | CLPP point-mutation knock-in |
| Where does CLPX localize in mitochondria? | CLPX tagged knock-in |
| Does CLPP overexpression induce stress? | CLPP overexpression cell lines |
| Does CLPB regulate calcium signalling? | CLPB knockout and overexpression |
| Does bacterial clpP deletion alter dormancy? | Bacterial clpP deletion strains |
How to Study the endopeptidase Clp complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Affinity purification-MS | Subunit composition and interactors | Clp complex assembly |
| In vitro proteolysis assay | ATP-dependent degradation rate | ClpP activity |
| Fluorescence microscopy | Subcellular localization | Mitochondrial ClpP |
| RNA-seq | Transcriptional changes | ATF4 stress response |
| CRISPR knockout | Gene function loss | CLPP/CLPX dependency |
| CRISPR knock-in | Tagged or mutant protein expression | Localization and point mutations |
| Bacterial dormancy assay | Dormancy depth and antibiotic tolerance | clpP/clpX mutants |
| Metal sequestration assay | Adaptation to metal stress | S. aureus clpC/clpP |
Proteomics and interactomics
Affinity purification coupled to mass spectrometry can identify Clp complex subunits and substrates, revealing composition and assembly states.
Functional assays for proteolysis
Casein or peptide-based degradation assays measure ATP-dependent proteolytic activity of Clp complexes in vitro and in cell lysates.
Imaging and localization
Fluorescence microscopy of tagged Clp subunits reveals mitochondrial or bacterial localization and assembly dynamics.
Transcriptomics and stress response
RNA-seq and multi-omics can identify ATF4-dependent and ClpP-dependent transcriptional programs during mitochondrial stress.
How CRISPR Can Be Used to Study GO:0009368 endopeptidase Clp complex
Knockout
CRISPR knockout of CLPP or CLPX in cancer cell lines can test whether Clp complex activity is required for viability and mitochondrial function.
Point Mutation
Point mutations in the catalytic site of CLPP can dissect which residues are essential for proteolysis and for drug-induced lethality.
Knock-in
Tagged knock-in of CLPX or CLPP allows live-cell imaging and proteomic pull-down of the complex in its native context.
Overexpression
Overexpression of CLPP or CLPB can model stress conditions and test whether increased Clp activity is sufficient to trigger mitochondrial responses.
How EDITGENE Supports endopeptidase Clp complex Research
Researchers studying endopeptidase Clp complex-related genes often need to determine whether a candidate gene is causally involved in proteolysis, stress response or disease. EDITGENE provides the CRISPR tools and cell models required to move from correlation to causation.
Contact EDITGENE today to design your custom CRISPR model for endopeptidase Clp complex research.
Frequently Asked Questions About endopeptidase Clp complex
What is the endopeptidase Clp complex?
It is a protein complex defined by GO:0009368, composed of ClpX, ClpC, ClpD, ClpP or ClpR family members, where ClpP is the proteolytic subunit and ClpA/ClpX are regulatory subunits.
What genes are involved in the endopeptidase Clp complex?
Key genes include CLPP, CLPX, CLPC, CLPD, CLPR, CLPA, CLPB and their bacterial homologs clpP, clpX and clpC.
What is the function of GO:0009368?
It mediates ATP-dependent proteolysis of damaged or regulatory proteins and can exist in active or inactive forms.
Is ClpP a cancer target?
Yes, mitochondrial ClpP activation induces selective cancer cell lethality, and ClpP agonists such as TR-107 inhibit colorectal cancer cell growth.
How do bacteria use Clp complexes?
Bacterial Clp complexes regulate dormancy depth and antibiotic tolerance, and they are activated by acyldepsipeptides.
What is the role of CLPB?
CLPB is a mitochondrial disaggregase that maintains calcium signalling and dynamics and functionally interacts with the Clp system.
How can I study Clp complex function?
CRISPR knockout, point-mutation, knock-in and overexpression models combined with proteomics and imaging are standard approaches.
What diseases are linked to Clp complex dysfunction?
Cancer, bacterial infection and mitochondrial stress-related conditions are linked to Clp complex activity.
What is the difference between ClpP and ClpX?
ClpP is the proteolytic core, while ClpX is a regulatory ATPase that unfolds and translocates substrates.
Can Clp complexes be targeted by antibiotics?
Yes, acyldepsipeptides stimulate the Clp-ATPase/ClpP complex and represent a potential antibacterial strategy.
Conclusion
GO:0009368 (endopeptidase Clp complex) is a conserved ATP-dependent protease machine with critical roles in mitochondrial proteostasis, cancer cell survival, bacterial dormancy and antibiotic tolerance. Its subunit composition and assembly state determine whether it is active or inactive, making it a rich target for mechanistic and therapeutic research. CRISPR-based knockout, point-mutation, knock-in and overexpression models are essential to dissect Clp subunit function and to translate these findings into new anticancer and antibacterial strategies.
References
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- 2. Pu Y et al.. 2019. ATP-Dependent Dynamic Protein Aggregation Regulates Bacterial Dormancy Depth Critical for Antibiotic Tolerance.. Mol Cell 73(1):143-156.e4 PMID: 30472191
- 3. Quirós PM et al.. 2017. Multi-omics analysis identifies ATF4 as a key regulator of the mitochondrial stress response in mammals.. J Cell Biol 216(7):2027-2045 PMID: 28566324
- 4. Currie SQW et al.. 2026. Molecular mechanisms of mitochondrial AAA+ proteases.. J Biol Chem 302(3):111264 PMID: 41655698
- 5. Giarrizzo M et al.. 2024. TR-107, an Agonist of Caseinolytic Peptidase Proteolytic Subunit, Disrupts Mitochondrial Metabolism and Inhibits the Growth of Human Colorectal Cancer Cells.. Mol Cancer Ther 23(12):1761-1778 PMID: 39233476
- 6. Reinhardt L et al.. 2022. Antibiotic Acyldepsipeptides Stimulate the Streptomyces Clp-ATPase/ClpP Complex for Accelerated Proteolysis.. mBio 13(6):e0141322 PMID: 36286522
- 7. Reyes Ruiz VM et al.. 2024. Coordinated adaptation of Staphylococcus aureus to calprotectin-dependent metal sequestration.. mBio 15(7):e0138924 PMID: 38920392
- 8. D'Angelo D et al.. 2025. Dependence of mitochondrial calcium signalling and dynamics on the disaggregase, CLPB.. Nat Commun 16(1):2810 PMID: 40118824
