GO:0002135 CTP binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0002135 CTP binding describes the molecular function of selectively binding cytidine 5'-triphosphate (CTP), a pyrimidine nucleotide that serves as a substrate for nucleic acid synthesis and a regulatory ligand.
• CTP binding regulates diverse proteins including Noc, ParB, CTP synthase, and CTP:phosphoethanolamine cytidylyltransferase, controlling processes from chromosome segregation to membrane lipid synthesis.
• Structural studies reveal that CTP binding induces conformational changes that modulate DNA binding, enzyme activity, and liquid-liquid phase separation.
• Dysregulation of CTP-binding proteins is linked to cancer, antiviral immunity, and neurological disorders, making them attractive therapeutic targets.
• CRISPR-based knockout, point mutation, knock-in, and overexpression models are essential to dissect the causal roles of CTP-binding proteins in health and disease.
• EDITGENE provides comprehensive CRISPR services to accelerate research on CTP binding and its associated genes.
Description
CTP binding (GO:0002135) is a molecular function defined as the selective interaction with cytidine 5'-triphosphate (CTP), a pyrimidine nucleotide essential for RNA and DNA synthesis, as well as for phospholipid and sialic acid metabolism. This binding event is critical for the regulation of numerous proteins, including the nucleoid occlusion protein Noc, the partition protein ParB, CTP synthase, and CTP:phosphoethanolamine cytidylyltransferase. Understanding CTP binding is fundamental to deciphering how cells coordinate nucleotide-dependent processes such as chromosome segregation, cell division, and metabolic flux. Recent studies have highlighted the role of CTP binding in liquid-liquid phase separation of ParB and in the allosteric regulation of CTP synthase, underscoring its broad biological significance. Moreover, dysregulation of CTP-binding proteins has been implicated in cancer and antiviral immunity, making this GO term a focal point for therapeutic development. This article provides a comprehensive overview of the mechanisms, key genes, and research methodologies associated with CTP binding, based on authoritative QuickGO data and verified PubMed literature.
CTP binding At A Glance
| GO ID | GO:0002135 |
|---|---|
| GO term | CTP binding |
| Ontology | molecular_function |
| Synonym | None |
| Major function | Binding to CTP, a pyrimidine nucleotide involved in nucleic acid synthesis and metabolic regulation |
| Representative proteins | Noc, ParB, CTP synthase, CTP:phosphoethanolamine cytidylyltransferase |
| Associated processes | Chromosome segregation, cell division, phospholipid synthesis, antiviral immunity |
| Disease relevance | Cancer, viral infections, neurological disorders |
What Is GO:0002135?
CTP binding (GO:0002135) is the molecular function of selectively and non-covalently interacting with cytidine 5'-triphosphate (CTP), a ribonucleotide that serves as a substrate for RNA synthesis and as an energy carrier in some reactions. This binding can occur through specific domains or pockets that recognize the cytosine base, ribose sugar, and triphosphate moiety, often leading to conformational changes that regulate protein activity, localization, or interactions.
Why Is CTP binding Important in Cell Biology?
CTP binding is crucial for a wide array of cellular processes, from the regulation of bacterial chromosome segregation by Noc and ParB to the metabolic control of phospholipid synthesis by CTP:phosphoethanolamine cytidylyltransferase. In higher organisms, CTP synthase (CTPS) forms filamentous structures that are regulated by CTP binding, impacting nucleotide homeostasis and cell proliferation. Dysregulation of CTP-binding proteins has been linked to cancer progression and impaired antiviral responses, highlighting their potential as therapeutic targets. Thus, studying CTP binding provides insights into fundamental biology and disease mechanisms.
• CTP binding regulates the nucleoid occlusion protein Noc, which coordinates chromosome segregation with cell division in bacteria.
• ParB uses CTP binding to drive liquid-liquid phase separation, a process critical for partitioning chromosomal DNA during cell division.
• CTP synthase (CTPS) binds CTP as a product and allosteric regulator, forming filaments that modulate enzymatic activity.
• CTP:phosphoethanolamine cytidylyltransferase binds CTP to catalyze the rate-limiting step in phosphatidylethanolamine synthesis.
• Dysregulation of CTP-binding proteins is implicated in cancer, as seen with hCTPS1 filamentation and CTP synthetase 1-mediated IRF3 deamidation.
• CTP binding is essential for antiviral interferon induction, as CTP synthetase 1 suppresses IRF3 through deamidation.
• Structural studies of CTP-binding domains inform drug design targeting bacterial cell division and nucleotide metabolism.
• CRISPR-based models enable precise manipulation of CTP-binding genes to study their roles in development and disease.
• Understanding CTP binding aids in the development of antibiotics and anticancer agents.
• Research on CTP binding contributes to the broader field of nucleotide-dependent signaling and regulation.
Molecular Mechanism of CTP binding
CTP Recognition and Binding Pocket
In simple terms: Proteins have specific pockets that fit CTP like a lock and key.
CTP binding proteins typically contain a conserved nucleotide-binding domain that recognizes the cytosine base, ribose, and triphosphate moieties. For example, the nucleoid occlusion protein Noc binds CTP through a pocket that undergoes conformational changes upon ligand binding, as revealed by structural studies. Similarly, CTP synthase has an allosteric site for CTP that regulates its activity.
Conformational Changes and Allostery
In simple terms: When CTP binds, it changes the shape of the protein, altering its function.
CTP binding often induces conformational changes that modulate protein activity. In Noc, CTP binding regulates its membrane-binding activity, which is essential for proper chromosome segregation. In CTP synthase, CTP binding at the allosteric site promotes filament formation and inhibits enzymatic activity. These allosteric effects are critical for feedback regulation of pyrimidine synthesis.
Role in Liquid-Liquid Phase Separation
In simple terms: CTP helps proteins form droplets that organize cellular processes.
ParB binds CTP to undergo liquid-liquid phase separation, forming condensates that are essential for chromosomal partitioning in bacteria. This phase separation is controlled by CTP hydrolysis and is critical for ParB's function in chromosome segregation. The CTP-binding domain of ParB is required for this process, linking nucleotide binding to large-scale cellular organization.
Enzymatic Function and Catalysis
In simple terms: Some proteins use CTP as a building block or energy source for chemical reactions.
CTP:phosphoethanolamine cytidylyltransferase binds CTP to catalyze the formation of CDP-ethanolamine, a key intermediate in phosphatidylethanolamine synthesis. This enzyme uses CTP as a substrate, and its binding is essential for lipid metabolism. Similarly, CTP synthase binds CTP as a product and regulates its own synthesis through feedback inhibition.
Regulation by CTP Levels
In simple terms: The amount of CTP in the cell controls how these proteins work.
Cellular CTP levels fluctuate in response to metabolic demands and can regulate CTP-binding proteins. For instance, CTP binding to Noc inhibits its DNA-binding activity, ensuring proper timing of chromosome segregation. In CTP synthase, high CTP levels promote filament formation and inhibit activity, maintaining nucleotide homeostasis. This feedback regulation is crucial for balancing pyrimidine pools.
Key Genes Involved in GO:0002135 CTP binding
The following genes encode proteins that bind CTP and are involved in diverse cellular processes, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| Noc | Nucleoid occlusion protein; binds CTP to regulate membrane binding and chromosome segregation | Bacterial cell division and chromosome organization |
| ParB | Partition protein; CTP binding drives liquid-liquid phase separation for chromosome partitioning | Bacterial chromosome segregation and phase separation |
| CTPS1 | CTP synthase 1; binds CTP as product and allosteric regulator; forms filaments | Cancer, antiviral immunity, nucleotide metabolism |
| CTPS2 | CTP synthase 2; similar to CTPS1 but tissue-specific | Nucleotide metabolism and potential drug target |
| PCYT2 | CTP:phosphoethanolamine cytidylyltransferase; binds CTP for phospholipid synthesis | Lipid metabolism and membrane biogenesis |
| IMPDH1 | Inosine monophosphate dehydrogenase 1; indirectly related to CTP synthesis | Purine metabolism and cancer |
| IMPDH2 | Inosine monophosphate dehydrogenase 2; involved in guanine nucleotide synthesis | Cancer and immune responses |
| CAD | Carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase; involved in pyrimidine synthesis | Pyrimidine biosynthesis and cancer |
| DHODH | Dihydroorotate dehydrogenase; catalyzes a step in pyrimidine synthesis | Cancer and autoimmune diseases |
| UMPS | Uridine monophosphate synthetase; involved in pyrimidine synthesis | Cancer and developmental disorders |
| CTPS1 (human) | Human CTP synthase 1; filamentation with CTP | Cancer and antiviral immunity |
| Noc (Bacillus subtilis) | Model protein for CTP binding and DNA binding | Bacterial cell division |
| ParB (Bacillus subtilis) | Model for CTP-controlled phase separation | Chromosome segregation |
| CTP synthase (E. coli) | Bacterial CTP synthase; structural and regulatory studies | Antibiotic target |
| PCYT2 (human) | Human CTP:phosphoethanolamine cytidylyltransferase | Lipid metabolism disorders |
| IRF3 | Interferon regulatory factor 3; deamidated by CTPS1, affecting antiviral response | Antiviral immunity |
| CTPS1 (mouse) | Mouse CTP synthase 1; model for filamentation | Cancer and immunity |
How Is CTP binding Regulated?
CTP binding is regulated by cellular CTP levels, which fluctuate with metabolic state. For example, in Noc, CTP binding inhibits DNA binding, and this inhibition is relieved when CTP levels drop, allowing Noc to bind DNA and coordinate cell division. In CTP synthase, CTP acts as a feedback inhibitor by promoting filament formation, which reduces enzymatic activity. Additionally, post-translational modifications and interacting proteins can modulate CTP binding; for instance, CTPS1 filamentation is regulated by phosphorylation and other signals. In ParB, CTP hydrolysis is required for phase separation dynamics, and the process is regulated by the nucleotide state.
CTP binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CTPS1 | Cancer, antiviral immunity | Knockout and overexpression in cancer cell lines; point mutations in CTP-binding site |
| PCYT2 | Hereditary spastic paraplegia | Knock-in of patient mutations in iPSCs; knockout in neuronal cells |
| Noc | Bacterial cell division | Bacterial knockout and point mutation models |
| ParB | Chromosome segregation | Bacterial knockout and phase separation assays |
| IRF3 | Antiviral immunity | Knockout and deamidation-resistant knock-in in immune cells |
Cancer
CTP synthase 1 (CTPS1) is overexpressed in various cancers and its filamentation, driven by CTP binding, contributes to tumor cell proliferation. Inhibition of CTPS1 activity or disruption of CTP binding may offer therapeutic strategies. Additionally, CTP synthetase 1 deamidates IRF3, suppressing antiviral interferon induction, which could impact cancer immunotherapy.
Antiviral Immunity
CTP synthetase 1 (CTPS1) suppresses antiviral interferon induction by deamidating IRF3, a process that may depend on CTP binding. This highlights the role of CTP-binding proteins in immune evasion and suggests that targeting CTPS1 could enhance antiviral responses.
Neurological Disorders
Mutations in PCYT2, which binds CTP for phospholipid synthesis, cause hereditary spastic paraplegia and other neurological disorders. Disruption of CTP binding in PCYT2 leads to impaired phosphatidylethanolamine synthesis, affecting membrane integrity in neurons.
Bacterial Infections
Bacterial proteins like Noc and ParB require CTP binding for essential functions in chromosome segregation and cell division. Targeting these CTP-binding proteins could lead to new antibiotics, as their inhibition would disrupt bacterial proliferation.
From CTP binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does CTP binding regulate Noc membrane association? | Point mutation of CTP-binding residues in Noc; knockout |
| How does CTP binding affect ParB phase separation? | Knock-in of CTP-binding deficient ParB; live-cell imaging |
| What is the role of CTPS1 filamentation in cancer? | Overexpression of wild-type and CTP-binding mutant CTPS1 in cancer cells |
| Does PCYT2 CTP binding deficiency cause neurodegeneration? | Knock-in of patient mutations in iPSC-derived neurons |
| Can targeting CTP-binding proteins inhibit bacterial growth? | Bacterial knockout and small-molecule screening |
| How does CTPS1 deamidation of IRF3 affect antiviral response? | Knockout of CTPS1 in immune cells; overexpression of deamidase-dead mutant |
How to Study the CTP binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| X-ray crystallography | Atomic structure of protein-CTP complex | Determining binding pocket and conformational changes |
| Cryo-EM | High-resolution structure of large complexes | Visualizing filament formation of CTPS |
| ITC | Binding affinity (Kd) | Quantifying CTP binding to purified proteins |
| SPR | Real-time binding kinetics | Measuring association/dissociation rates |
| Enzymatic assay | Catalytic activity | Assessing CTP synthase or PCYT2 activity |
| Fluorescence microscopy | Protein localization and condensation | Observing ParB phase separation |
| CRISPR knockout screen | Gene essentiality and pathway identification | Finding modifiers of CTP-binding protein function |
| Proteomics | Protein interactions and modifications | Identifying CTP-dependent interactors |
Structural Biology
X-ray crystallography and cryo-EM are used to determine the atomic structures of CTP-binding proteins in complex with CTP, revealing binding modes and conformational changes. These methods are essential for understanding the molecular basis of CTP recognition.
Biochemical Assays
Isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) measure binding affinity between CTP and target proteins. Enzymatic assays assess the impact of CTP binding on catalytic activity, such as CTP synthase or PCYT2.
Cell Imaging
Fluorescence microscopy and live-cell imaging visualize the formation of filaments or phase-separated condensates by CTP-binding proteins, such as CTPS1 filaments and ParB condensates.
CRISPR Screening
Genome-wide CRISPR knockout screens identify genes that modulate CTP-binding protein function or cellular sensitivity to CTP analogs, uncovering pathways and potential drug targets.
How CRISPR Can Be Used to Study GO:0002135 CTP binding
Knockout
CRISPR knockout of genes encoding CTP-binding proteins (e.g., CTPS1, PCYT2, Noc, ParB) allows researchers to assess their essentiality and downstream effects. For example, CTPS1 knockout in cancer cell lines reduces proliferation, validating it as a target.
Point Mutation
Introducing point mutations in the CTP-binding pocket (e.g., in Noc or ParB) via CRISPR base editing or homology-directed repair can specifically abolish CTP binding without affecting protein stability, enabling precise structure-function studies.
Knock-in
Knock-in of disease-associated mutations (e.g., in PCYT2) or tagged versions (e.g., GFP-CTPS1) allows tracking of protein localization and function in physiologically relevant models.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of wild-type or mutant CTP-binding proteins (e.g., CTPS1) can model gain-of-function effects in cancer and immunity.
How EDITGENE Supports CTP binding Research
Researchers studying CTP binding-related genes often need to determine whether a candidate gene is causally involved in a specific cellular process or disease. EDITGENE provides a suite of CRISPR-based services to enable precise genetic manipulation, from knockout to knock-in, accelerating functional validation and therapeutic target discovery.
Contact EDITGENE today to design your custom CRISPR model for CTP binding research.
Frequently Asked Questions About CTP binding
What is CTP binding?
CTP binding (GO:0002135) is the molecular function of selectively interacting with cytidine 5'-triphosphate (CTP), a nucleotide involved in RNA synthesis and metabolic regulation.
What genes are involved in CTP binding?
Key genes include Noc, ParB, CTPS1, CTPS2, and PCYT2, which encode proteins that bind CTP for various cellular functions.
How does CTP binding regulate cell division?
In bacteria, CTP binding to Noc and ParB regulates chromosome segregation and cell division by controlling DNA binding and phase separation.
What diseases are associated with CTP binding?
Dysregulation of CTP-binding proteins is linked to cancer, antiviral immunity, and neurological disorders such as hereditary spastic paraplegia.
What methods are used to study CTP binding?
Common methods include X-ray crystallography, ITC, SPR, fluorescence microscopy, and CRISPR screens.
How can CRISPR help study CTP binding?
CRISPR enables knockout, point mutation, knock-in, and overexpression of CTP-binding genes to dissect their functions and disease roles.
What is the role of CTP synthase in cancer?
CTP synthase 1 (CTPS1) is overexpressed in cancers and its filamentation, driven by CTP binding, promotes proliferation, making it a therapeutic target.
How does CTP binding affect antiviral immunity?
CTP synthetase 1 deamidates IRF3, suppressing interferon induction, a process that may depend on CTP binding.
What is the structure of CTP-binding proteins?
They typically contain a nucleotide-binding domain that recognizes CTP, often with conformational changes upon binding.
Can CTP binding be targeted for antibiotics?
Yes, bacterial CTP-binding proteins like Noc and ParB are essential for cell division and are potential antibiotic targets.
Conclusion
CTP binding (GO:0002135) is a fundamental molecular function that regulates diverse proteins involved in chromosome segregation, nucleotide metabolism, and phospholipid synthesis. Its dysregulation contributes to cancer, immune evasion, and neurological disorders. Advances in structural biology and CRISPR-based models continue to unravel the mechanistic details and therapeutic potential of CTP-binding proteins. EDITGENE offers comprehensive CRISPR services to support research on CTP binding and its associated genes, from knockout to library screening.
References
- 1. Jalal ASB et al.. 2021. CTP regulates membrane-binding activity of the nucleoid occlusion protein Noc.. Mol Cell 81(17):3623-3636.e6 PMID: 34270916
- 2. Sukhoverkov KV et al.. 2023. The CTP-binding domain is disengaged from the DNA-binding domain in a cocrystal structure of Bacillus subtilis Noc-DNA complex.. J Biol Chem 299(4):103063 PMID: 36841481
- 3. Zhou X et al.. 2021. Structural basis for ligand binding modes of CTP synthase.. Proc Natl Acad Sci U S A 118(30) PMID: 34301892
- 4. Bladergroen BA et al.. 1997. CTP:phosphoethanolamine cytidylyltransferase.. Biochim Biophys Acta 1348(1-2):91-9 PMID: 9370320
- 5. Guo CJ et al.. 2025. Filamentation of hCTPS1 with CTP.. Cell Biosci 15(1):112 PMID: 40739251
- 6. Rao Y et al.. 2025. Pyrimidine synthesis enzyme CTP synthetase 1 suppresses antiviral interferon induction by deamidating IRF3.. Immunity 58(1):74-89.e6 PMID: 39719712
- 7. Guo CJ et al.. 2024. Structural Basis of Bifunctional CTP/dCTP Synthase.. J Mol Biol 436(20):168750 PMID: 39173734
- 8. Babl L et al.. 2022. CTP-controlled liquid-liquid phase separation of ParB.. J Mol Biol 434(2):167401 PMID: 34902429
