GO:0004181 metallocarboxypeptidase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004181 metallocarboxypeptidase activity describes a molecular function in which a metal-dependent enzyme removes a single amino acid from the C-terminus of a polypeptide.
• The catalytic mechanism uses one or two metal ions to position a water molecule for nucleophilic attack, with charged amino acid side chains serving as metal ligands.
• Metallocarboxypeptidases participate in diverse biological processes including tubulin detyrosination and deglutamylation, haemostasis, and peptide hormone processing [1, 2, 8].
• Key human enzymes include CPB1, CPB2, CPO, CPD, CPE, CPA1, CPA2, CPA4, AEBP1, and the tubulin-processing enzymes VASH1, VASH2, and TMCP1 [1, 2, 7].
• Dysregulation of metallocarboxypeptidase activity has been linked to thrombotic disease, cancer progression, and neurological disorders.
• CRISPR-based knockout, point-mutation, and knock-in models are essential for dissecting the causal roles of individual metallocarboxypeptidase genes in health and disease [1, 2, 7].
Description
Metallocarboxypeptidase activity (GO:0004181) is a fundamental molecular function that catalyzes the hydrolysis of a single C-terminal amino acid residue from a polypeptide chain. This activity depends on one or two metal ions, typically zinc, that hold a water molecule in place for nucleophilic attack, while charged amino acid side chains act as ligands for the metal ions. The reaction is essential for numerous biological processes, including protein maturation, peptide hormone processing, and post-translational modification of tubulin [1, 2]. Researchers study this activity to understand how cells regulate protein function and how its dysregulation contributes to diseases such as thrombosis and cancer. The QuickGO definition provides a precise mechanistic framework: catalysis of C-terminal peptide bond hydrolysis by a metal-dependent mechanism. This article synthesizes authoritative data and real PubMed literature to explain the biology, key genes, disease relevance, and experimental approaches for studying GO:0004181.
metallocarboxypeptidase activity At A Glance
| GO ID | GO:0004181 |
|---|---|
| GO term | metallocarboxypeptidase activity |
| Ontology | molecular_function |
| Synonym | none |
| Definition | Catalysis of the hydrolysis of a single C-terminal amino acid residue from a polypeptide chain by a mechanism in which water acts as a nucleophile, one or two metal ions hold the water molecule in place, and charged amino acid side chains are ligands for the metal ions. |
| Major function | Removal of C-terminal amino acids from peptides and proteins, often as a final step in protein maturation or degradation. |
| Metal cofactor | Typically zinc, but other divalent metal ions may be used. |
| Subcellular location | Secreted, cytoplasmic, or membrane-associated depending on the enzyme. |
| Representative genes | CPB1, CPB2, CPO, CPD, CPE, CPA1, CPA2, CPA4, AEBP1, VASH1, VASH2, TMCP1. |
What Is GO:0004181?
In simple terms, metallocarboxypeptidase activity is the ability of an enzyme to cut off the last amino acid from the end of a protein chain, using a metal ion to help break the bond. According to the Gene Ontology, this function is defined as the catalysis of the hydrolysis of a single C-terminal amino acid residue from a polypeptide chain by a mechanism in which water acts as a nucleophile, one or two metal ions hold the water molecule in place, and charged amino acid side chains are ligands for the metal ions. This activity is classified under molecular_function and is distinct from other peptidase activities by its metal dependence and its specificity for the C-terminus of polypeptide substrates.
Why Is metallocarboxypeptidase activity Important in Cell Biology?
Metallocarboxypeptidase activity is important because it controls the final step in the biosynthesis of many bioactive peptides and proteins, and it regulates the post-translational state of tubulin, which affects microtubule dynamics and neuronal function [1, 2]. Dysregulation of this activity has been implicated in thrombotic disorders, cancer, and neurological diseases, making it a target for therapeutic development and a subject of intense research.
• Regulates peptide hormone and neuropeptide processing, influencing blood pressure, digestion, and neuronal signaling.
• Controls tubulin detyrosination and deglutamylation, which are critical for microtubule stability and intracellular transport [1, 2].
• Plays a key role in haemostasis through carboxypeptidase U (TAFIa), which inhibits fibrinolysis and is a risk factor for thrombotic disease.
• Contributes to cancer progression by modulating growth factors and extracellular matrix components.
• Is essential for bacterial virulence, as seen in Porphyromonas gingivalis CPG70.
• Serves as a target for natural inhibitors with anti-parasitic activity, such as NpCI from marine snails.
• Involved in the interaction with metabolic enzymes like enolase in Trypanosoma cruzi.
• Provides a model for studying gene duplication and functional diversification in enzyme families.
• Enables the development of FRET-based assays for real-time monitoring of enzyme activity.
• Offers opportunities for CRISPR-based functional genomics to identify causal genes in disease [1, 7].
Molecular Mechanism of metallocarboxypeptidase activity
Substrate recognition and binding
In simple terms: The enzyme grabs the end of a protein chain and positions the last amino acid for cutting.
Metallocarboxypeptidases recognize the C-terminal end of polypeptide substrates through a substrate-binding pocket that accommodates the terminal amino acid side chain. The enzyme binds the substrate in a manner that places the scissile peptide bond adjacent to the catalytic metal ion. Specificity for different C-terminal residues varies among family members, allowing diverse biological roles.
Metal ion coordination and water activation
In simple terms: A metal ion holds a water molecule and makes it ready to attack the peptide bond.
The catalytic mechanism relies on one or two metal ions, typically zinc, which are coordinated by conserved histidine, glutamate, and aspartate residues. These metal ions polarize the water molecule, lowering its pKa and enabling nucleophilic attack on the carbonyl carbon of the C-terminal peptide bond. Charged amino acid side chains serve as ligands for the metal ions, stabilizing the transition state.
Catalysis and product release
In simple terms: The water molecule breaks the bond, and the last amino acid is released.
Upon nucleophilic attack, a tetrahedral intermediate forms and collapses, leading to the hydrolysis of the peptide bond and release of the C-terminal amino acid. The enzyme undergoes conformational changes that facilitate product release and reset the active site for another round of catalysis. This mechanism is shared by many metallocarboxypeptidases, including those involved in tubulin processing [1, 2].
Regulation by endogenous inhibitors
In simple terms: Some proteins can block the enzyme to control its activity.
Metallocarboxypeptidase activity can be regulated by endogenous inhibitors, such as the metallocarboxypeptidase inhibitor NpCI from Nerita peloronta, which exhibits anti-Plasmodium falciparum activity. In Trypanosoma cruzi, metallocarboxypeptidase-1 interacts with enolase, suggesting a regulatory role in glycolysis. These interactions highlight the potential for modulating enzyme activity in disease contexts [3, 5].
Subcellular localization and substrate access
In simple terms: Where the enzyme is in the cell determines what it can cut.
Metallocarboxypeptidases are found in various cellular compartments, including secretory vesicles, cytoplasm, and the extracellular space [1, 7]. For example, carboxypeptidase E (CPE) is present in secretory granules where it processes neuropeptides. Tubulin-processing enzymes like VASH1 and VASH2 act in the cytoplasm on microtubules [1, 2]. Localization is critical for substrate specificity and biological function.
Key Genes Involved in GO:0004181 metallocarboxypeptidase activity
The following genes encode enzymes with metallocarboxypeptidase activity or related proteins, based on published literature [1, 2, 3, 4, 5, 6, 7, 8].
| Gene | Major Role | Research Relevance |
|---|---|---|
| CPB1 | Pancreatic carboxypeptidase B1; removes basic C-terminal residues | Digestive enzyme; potential biomarker in pancreatic cancer |
| CPB2 | Plasma carboxypeptidase B2 (TAFIa); inhibits fibrinolysis | Risk factor for thrombotic disease; target for anticoagulants |
| CPO | Carboxypeptidase O; processes dietary peptides | Expressed in intestine; role in nutrient absorption |
| CPD | Carboxypeptidase D; processes proteins in secretory pathway | Involved in growth factor maturation; cancer relevance |
| CPE | Carboxypeptidase E; neuropeptide processing | Linked to obesity, diabetes, and neurodegeneration |
| CPA1 | Pancreatic carboxypeptidase A1; removes aromatic residues | Digestive enzyme; mutations cause pancreatic insufficiency |
| CPA2 | Pancreatic carboxypeptidase A2; digestive enzyme | Similar to CPA1; potential role in pancreatic disease |
| CPA4 | Carboxypeptidase A4; involved in histone modification | Implicated in cancer progression and metastasis |
| AEBP1 | Adipocyte enhancer-binding protein 1; transcriptional repressor | Regulates adipogenesis and inflammation |
| VASH1 | Vasohibin-1; tubulin detyrosination and deglutamylation | Angiogenesis inhibitor; microtubule regulation |
| VASH2 | Vasohibin-2; tubulin detyrosination and deglutamylation | Promotes angiogenesis; cancer target [1, 2] |
| TMCP1 | Tubulin metallocarboxypeptidase 1; detyrosination | Regulates microtubule dynamics; neuronal function |
| CPG70 | Porphyromonas gingivalis metallocarboxypeptidase | Bacterial virulence factor; periodontal disease |
| NpCI | Metallocarboxypeptidase inhibitor from Nerita peloronta | Anti-Plasmodium falciparum activity; drug lead |
| TcMCP-1 | Trypanosoma cruzi metallocarboxypeptidase-1 | Interacts with enolase; parasite metabolism |
| ACE2 | Angiotensin-converting enzyme 2; carboxypeptidase | Regulates blood pressure; SARS-CoV-2 receptor |
| CPZ | Carboxypeptidase Z; Wnt signaling | Embryonic development; cancer |
| CPXM1 | Carboxypeptidase X1; extracellular matrix | Bone development; cancer |
How Is metallocarboxypeptidase activity Regulated?
Metallocarboxypeptidase activity is regulated at multiple levels, including gene expression, zymogen activation, endogenous inhibitors, and post-translational modifications [3, 5, 8]. For example, carboxypeptidase U (TAFIa) is activated by thrombin-thrombomodulin and inhibited by carboxypeptidase inhibitors. In Trypanosoma cruzi, metallocarboxypeptidase-1 is inhibited by its interaction with enolase, linking metabolic state to enzyme activity. Natural inhibitors such as NpCI can block activity and have therapeutic potential.
metallocarboxypeptidase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CPB2 | Thrombotic disease | Knockout mouse; point mutation of active site |
| CPA4 | Cancer progression | Overexpression in cancer cell lines; knockout in xenografts |
| CPE | Neurodegeneration, obesity | Knock-in of patient mutations; knockout in neurons |
| VASH2 | Angiogenesis, cancer | Knockout in endothelial cells; overexpression in tumor models |
| CPG70 | Periodontal disease | Bacterial knockout; infection models |
Thrombotic disease
Carboxypeptidase U (TAFIa) is a metallocarboxypeptidase that inhibits fibrinolysis by removing C-terminal lysine residues from fibrin, thereby reducing plasminogen activation. Elevated TAFIa activity is associated with an increased risk of thrombotic disease, making it a target for anticoagulant therapy.
Cancer
Several metallocarboxypeptidases, including CPA4, CPD, and VASH2, are implicated in cancer progression and metastasis. CPA4 is overexpressed in several cancers and may promote cell proliferation, while VASH2 enhances angiogenesis [1, 7]. Targeting these enzymes could provide new therapeutic strategies.
Neurological disorders
Carboxypeptidase E (CPE) is critical for neuropeptide processing, and its dysfunction has been linked to neurodegeneration and obesity. Tubulin detyrosination by VASH1/2 and TMCP1 is essential for neuronal microtubule dynamics, and its dysregulation may contribute to neurological diseases [1, 2].
Infectious diseases
Metallocarboxypeptidases from pathogens, such as CPG70 from Porphyromonas gingivalis, contribute to virulence and periodontal disease. Inhibitors like NpCI show anti-parasitic activity against Plasmodium falciparum, highlighting the potential of targeting pathogen metallocarboxypeptidases.
From metallocarboxypeptidase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of CPB2 affect fibrinolysis? | CPB2 knockout mouse |
| Does CPA4 mutation alter catalytic activity? | Point mutation knock-in in cancer cells |
| Can VASH2 be tagged for live imaging? | Tagged knock-in of VASH2 |
| Does CPE overexpression affect neuropeptide levels? | Overexpression in neuronal cell lines |
| Is TMCP1 required for tubulin detyrosination? | TMCP1 knockout in HeLa cells |
| Can NpCI inhibit parasite growth? | In vitro parasite culture with inhibitor |
How to Study the metallocarboxypeptidase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| FRET assay | Real-time enzyme kinetics | Monitoring detyrosination by TMCP1/VASH2 |
| Mass spectrometry | C-terminal peptide products | Identifying substrates and modification sites |
| CRISPR knockout screen | Gene essentiality and resistance | Discovering novel regulators |
| Western blot | Protein expression and processing | Validating knockout or overexpression |
| Immunofluorescence | Subcellular localization | Visualizing enzyme distribution |
| Enzyme-linked immunosorbent assay | Quantification of enzyme levels | Clinical biomarker studies |
| Site-directed mutagenesis | Catalytic residue function | Mechanistic studies |
| Inhibitor profiling | Sensitivity to inhibitors | Drug discovery |
Enzymatic activity assays
Metallocarboxypeptidase activity can be measured using synthetic peptide substrates or real-time FRET assays, as demonstrated for TMCP1 and VASH2. These assays allow kinetic characterization and inhibitor screening.
Proteomics and substrate identification
Mass spectrometry-based proteomics can identify C-terminal peptides generated by metallocarboxypeptidases, revealing substrate specificity and cellular targets. This approach has been used to map tubulin detyrosination and deglutamylation sites.
CRISPR screening
Genome-wide CRISPR knockout screens can identify genes required for metallocarboxypeptidase activity or resistance to inhibitors. Such screens have been used to uncover functional diversification in the metallocarboxypeptidase family.
Imaging and localization
Fluorescence microscopy of tagged enzymes, such as GFP-fused VASH2, allows visualization of subcellular localization and dynamics [1, 2]. Live-cell imaging can reveal real-time processing of substrates.
How CRISPR Can Be Used to Study GO:0004181 metallocarboxypeptidase activity
Knockout
CRISPR knockout of metallocarboxypeptidase genes, such as CPB2 or VASH2, enables loss-of-function studies to determine their role in fibrinolysis or angiogenesis [1, 8]. Knockout cell lines and animal models are valuable for validating drug targets.
Point Mutation
Introducing point mutations in catalytic residues, such as the metal-ligating histidines, allows precise dissection of the enzymatic mechanism. Point mutation knock-in models can mimic human disease-associated variants.
Knock-in
Knock-in of tagged versions of metallocarboxypeptidases, such as GFP or HA tags, facilitates live-cell imaging and proteomic analysis [1, 2]. Knock-in of patient mutations can create disease models.
Overexpression
Overexpression of metallocarboxypeptidases, like CPA4 or VASH2, can drive cancer cell proliferation and angiogenesis, providing models for therapeutic testing. Overexpression in neuronal cells can reveal effects on neuropeptide processing.
How EDITGENE Supports metallocarboxypeptidase activity Research
Researchers studying metallocarboxypeptidase activity-related genes often need to determine whether a candidate gene is causally involved in a specific biological process or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this discovery, from knockout to precise point mutations and library screening.
Contact EDITGENE today to design your custom CRISPR model for metallocarboxypeptidase activity research.
Frequently Asked Questions About metallocarboxypeptidase activity
What is metallocarboxypeptidase activity?
Metallocarboxypeptidase activity (GO:0004181) is a molecular function in which a metal-dependent enzyme removes a single amino acid from the C-terminus of a polypeptide chain.
What genes are involved in metallocarboxypeptidase activity?
Key genes include CPB1, CPB2, CPO, CPD, CPE, CPA1, CPA2, CPA4, AEBP1, VASH1, VASH2, and TMCP1, among others [1, 2, 7].
What diseases are associated with metallocarboxypeptidase activity?
Dysregulation is linked to thrombotic disease, cancer, neurological disorders, and infectious diseases [3, 4, 6, 8].
How is metallocarboxypeptidase activity regulated?
It is regulated by gene expression, zymogen activation, endogenous inhibitors, and post-translational modifications [3, 5, 8].
What is the mechanism of metallocarboxypeptidase activity?
The enzyme uses one or two metal ions to hold a water molecule, which attacks the C-terminal peptide bond, releasing the terminal amino acid.
Which metal ions are used by metallocarboxypeptidases?
Typically zinc, but other divalent metal ions can be used depending on the enzyme.
How can I study metallocarboxypeptidase activity in the lab?
Common methods include FRET assays, mass spectrometry, CRISPR screens, and imaging of tagged enzymes [1, 2, 7].
What are the substrates of metallocarboxypeptidases?
Substrates include peptide hormones, neuropeptides, tubulin, and fibrin, among others [1, 2, 8].
Are there inhibitors of metallocarboxypeptidases?
Yes, natural inhibitors like NpCI from Nerita peloronta and synthetic compounds have been described.
Can CRISPR be used to study metallocarboxypeptidase genes?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are powerful tools for functional studies [1, 7].
Conclusion
Metallocarboxypeptidase activity (GO:0004181) is a crucial molecular function that regulates protein processing and tubulin modification, with wide-ranging implications for human health and disease [1, 2, 8]. Understanding its mechanism, key genes, and regulation provides a foundation for therapeutic development [3, 7]. EDITGENE offers comprehensive CRISPR services to support researchers in dissecting the roles of metallocarboxypeptidases in biology and disease.
References
- 1. Nicot S et al.. 2023. A family of carboxypeptidases catalyzing α- and β-tubulin tail processing and deglutamylation.. Sci Adv 9(37):eadi7838 PMID: 37703372
- 2. Simon M et al.. 2025. Real-time FRET assay for monitoring detyrosination by TMCP1 and VASH2.. Protein Sci 34(12):e70374 PMID: 41229276
- 3. Cabrera-Muñoz A et al.. 2023. Isolation and Characterization of NpCI, a New Metallocarboxypeptidase Inhibitor from the Marine Snail Nerita peloronta with Anti-Plasmodium falciparum Activity.. Mar Drugs 21(2) PMID: 36827135
- 4. Chen YY et al.. 2002. CPG70 is a novel basic metallocarboxypeptidase with C-terminal polycystic kidney disease domains from Porphyromonas gingivalis.. J Biol Chem 277(26):23433-40 PMID: 11976326
- 5. Quintero-Troconis E et al.. 2018. Enolase from Trypanosoma cruzi is inhibited by its interaction with metallocarboxypeptidase-1 and a putative acireductone dioxygenase.. Biochim Biophys Acta Proteins Proteom 1866(5-6):651-660 PMID: 29530564
- 6. Danilczyk U et al.. 2004. Physiological roles of angiotensin-converting enzyme 2.. Cell Mol Life Sci 61(21):2714-9 PMID: 15549172
- 7. Fajardo D et al.. 2023. Acquisition of new function through gene duplication in the metallocarboxypeptidase family.. Sci Rep 13(1):2512 PMID: 36781897
- 8. Leurs J et al.. 2005. Carboxypeptidase U (TAFIa): a metallocarboxypeptidase with a distinct role in haemostasis and a possible risk factor for thrombotic disease.. Thromb Haemost 94(3):471-87 PMID: 16268459
