GO:0004827 proline-tRNA ligase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004827 (proline-tRNA ligase activity) is the molecular function that attaches L-proline to tRNA(Pro), a critical step in protein synthesis.
• The enzyme, prolyl-tRNA synthetase (ProRS), is a dual-domain protein with a catalytic core and a separate editing domain that proofreads mischarged amino acids.
• ProRS is a validated drug target in pathogens: inhibitors show antimalarial, antiviral, and antibacterial activity.
• In humans, mutations in the mitochondrial ProRS gene PARS2 cause developmental delay and seizures linked to integrated stress response activation.
• Phosphorylation of ProRS regulates its activity and interactions, and can be studied with experimental methods for aminoacyl-tRNA synthetase phosphorylation.
• CRISPR-based knockout, point-mutation, and knock-in models are essential to dissect ProRS function in disease and to validate drug targets.
Description
Proline-tRNA ligase activity (GO:0004827) is a fundamental molecular function that ensures the correct incorporation of the amino acid L-proline into nascent polypeptides during translation. This activity is catalyzed by prolyl-tRNA synthetase (ProRS), an enzyme that charges tRNA(Pro) with L-proline in an ATP-dependent two-step reaction. Accurate proline incorporation is vital for protein structure and function, particularly for proteins rich in proline motifs that mediate protein-protein interactions and signaling. Beyond its housekeeping role, ProRS has emerged as a promising therapeutic target in infectious diseases and cancer, and its dysregulation is linked to human genetic disorders. Understanding the molecular mechanism, regulation, and disease relevance of GO:0004827 is therefore of broad interest to researchers in biochemistry, microbiology, and translational medicine.
proline-tRNA ligase activity At A Glance
| GO ID | GO:0004827 |
|---|---|
| GO term | proline-tRNA ligase activity |
| Ontology | molecular_function |
| Synonym | prolyl-tRNA synthetase activity; proline translase activity; prolinyl-tRNA ligase activity; L-proline:tRNAPro ligase (AMP-forming) |
| Major function | Catalyzes the attachment of L-proline to tRNA(Pro) for protein synthesis |
| Reaction | ATP + L-proline + tRNA(Pro) = AMP + diphosphate + L-prolyl-tRNA(Pro) |
| Enzyme class | Aminoacyl-tRNA synthetase (ligase) |
| Subcellular location | Cytoplasm and mitochondria (in eukaryotes) |
| Pathological relevance | Target for anti-infectives; mutations cause mitochondrial disease |
What Is GO:0004827?
According to the Gene Ontology, proline-tRNA ligase activity (GO:0004827) is defined as the catalysis of the reaction: ATP + L-proline + tRNA(Pro) = AMP + diphosphate + L-prolyl-tRNA(Pro). In other words, this activity uses the energy from ATP to covalently attach the amino acid L-proline to its corresponding transfer RNA, forming a charged tRNA that can deliver proline to the ribosome during protein synthesis.
Why Is proline-tRNA ligase activity Important in Cell Biology?
Proline-tRNA ligase activity is essential for translating the genetic code into functional proteins, and its fidelity is maintained by a dedicated editing domain that hydrolyzes mischarged tRNA species. Because proline is unique among amino acids, ProRS is structurally distinct and thus an attractive target for drugs against pathogens such as Plasmodium, mammarenaviruses, and multidrug-resistant bacteria. In humans, mutations in the mitochondrial ProRS (PARS2) cause severe neurodevelopmental disorders, and the enzyme is subject to regulation by phosphorylation and the integrated stress response. Consequently, studying GO:0004827 informs basic translation biology, antimicrobial drug discovery, and the molecular basis of rare diseases.
• Essential for protein synthesis: ProRS charges tRNA(Pro) with proline, a prerequisite for translation.
• Drug target in malaria: ProRS inhibitors are active against Plasmodium falciparum, and resistance mechanisms involve amino acid transporters.
• Antiviral target: ProRS is required for mammarenavirus multiplication, highlighting its potential for antiviral development.
• Antibacterial target: Inhibitors of bacterial ProRS show activity against multidrug-resistant strains and Mycobacterium tuberculosis.
• Human disease: Mutations in PARS2 cause developmental delay and seizures via integrated stress response activation.
• Regulation: ProRS activity is modulated by phosphorylation, affecting its function in translation and signaling.
• Editing function: The editing domain prevents misincorporation of similar amino acids, maintaining proteome integrity.
• Research tool: ProRS is a model for studying aminoacyl-tRNA synthetase mechanism and drug resistance.
Molecular Mechanism of proline-tRNA ligase activity
Substrate recognition and activation
In simple terms: The enzyme first grabs proline and ATP, then activates proline by attaching AMP to it.
Prolyl-tRNA synthetase (ProRS) binds L-proline and ATP in its catalytic core, forming a prolyl-adenylate intermediate with the release of pyrophosphate. This step is highly specific for proline, and the enzyme discriminates against similar amino acids through shape and chemical complementarity.
tRNA charging and proofreading
In simple terms: The activated proline is transferred to tRNA, and a separate editing domain checks for mistakes.
The prolyl group is transferred to the 3'-end of tRNA(Pro), forming L-prolyl-tRNA(Pro). A distinct editing domain within ProRS hydrolyzes mischarged tRNA species, such as alanyl-tRNA(Pro), ensuring translational fidelity. This trans-acting editing domain is essential for accurate protein synthesis.
Catalytic cycle and energy consumption
In simple terms: The whole process uses ATP and releases AMP and pyrophosphate as byproducts.
The overall reaction consumes one ATP per proline charged, yielding AMP and diphosphate. This two-step mechanism is typical of class II aminoacyl-tRNA synthetases, to which ProRS belongs.
Regulation by phosphorylation
In simple terms: Adding phosphate groups to the enzyme can change how well it works.
ProRS is subject to phosphorylation, which can alter its catalytic activity, tRNA binding, or interactions with other proteins. Experimental approaches to study aminoacyl-tRNA synthetase phosphorylation include metabolic labeling and phosphoproteomics.
Inhibition and drug targeting
In simple terms: Small molecules can block the enzyme, killing pathogens or cancer cells.
ProRS is a validated target for anti-infective agents. Inhibitors such as 3-benzamidopyrazine-2-carboxamides and fluorine-tuned compounds bind the catalytic site and show activity against bacteria and parasites. Resistance can arise through mutations or metabolic bypass.
Key Genes Involved in GO:0004827 proline-tRNA ligase activity
The following genes encode prolyl-tRNA synthetases or related factors that directly influence proline-tRNA ligase activity across species.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PARS2 (human) | Mitochondrial prolyl-tRNA synthetase | Mutations cause developmental delay and seizures; ISR activation |
| PARS1 (human) | Cytoplasmic prolyl-tRNA synthetase | Target for anticancer and antiviral drugs; phosphorylation studies |
| PRS (P. falciparum) | Prolyl-tRNA synthetase | Target of antimalarial inhibitors; resistance via amino acid transporter |
| Prs (mammarenavirus host) | Prolyl-tRNA synthetase | Required for viral multiplication; antiviral target |
| ProRS (M. tuberculosis) | Prolyl-tRNA synthetase | Target for antimycobacterial inhibitors |
| ProRS (bacteria) | Prolyl-tRNA synthetase | Inhibitors show broad-spectrum antibacterial activity |
| AARS1 (human) | Alanyl-tRNA synthetase | Related synthetase; editing mechanisms comparable |
| EPRS1 (human) | Glutamyl-prolyl-tRNA synthetase | Bifunctional synthetase; links translation to signaling |
| IARS1 (human) | Isoleucyl-tRNA synthetase | Model for synthetase phosphorylation |
| LARS1 (human) | Leucyl-tRNA synthetase | mTOR regulation; related synthetase |
| MARS1 (human) | Methionyl-tRNA synthetase | Phosphorylation target |
| KARS1 (human) | Lysyl-tRNA synthetase | Disease-linked synthetase |
| GCN2 (human) | eIF2α kinase | Mediates ISR upon ProRS deficiency |
| ATF4 (human) | Transcription factor | ISR effector downstream of PARS2 deficiency |
| DDIT3 (CHOP) | Stress-induced transcription factor | ISR marker in ProRS-related stress |
| tRNA(Pro) genes | Transfer RNA for proline | Substrate for charging; mutations affect translation |
| ProRS editing domain | Proofreading domain | Ensures fidelity; target for mechanistic studies |
How Is proline-tRNA ligase activity Regulated?
Proline-tRNA ligase activity is regulated at multiple levels. Phosphorylation of ProRS can modulate its catalytic efficiency and interactions, and experimental methods such as metabolic labeling with 32P and phospho-specific antibodies are used to study this. In mitochondria, deficiency of PARS2 activates the integrated stress response (ISR) through GCN2-mediated phosphorylation of eIF2α, leading to ATF4 and CHOP induction. Additionally, in pathogens, resistance to ProRS inhibitors can arise from mutations in the enzyme or from metabolic changes, such as elevated intracellular proline due to transporter disruption. These regulatory mechanisms influence both normal physiology and disease states.
proline-tRNA ligase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PARS2 | Developmental delay and seizures (mitochondrial disease) | Patient fibroblasts, PARS2 KO mice, iPSC-derived neurons |
| PRS (P. falciparum) | Malaria; resistance to ProRS inhibitors | Parasite cultures with transporter KO, mouse infection models |
| ProRS (mammarenavirus) | Viral multiplication; antiviral target | Virus-infected cells with ProRS KO or inhibitors |
| ProRS (M. tuberculosis) | Tuberculosis; drug resistance | M. tuberculosis cultures, macrophage infection models |
| ProRS (bacteria) | Multidrug-resistant infections | Clinical isolates, efflux pump KO strains |
Mitochondrial prolyl-tRNA synthetase deficiency (PARS2)
Biallelic mutations in PARS2 cause a severe neurodevelopmental disorder characterized by developmental delay and seizures. Studies in patient cells and animal models show that loss of PARS2 function triggers the integrated stress response, contributing to neuronal dysfunction.
Infectious diseases: malaria, viral, and bacterial infections
ProRS is essential for the survival of Plasmodium falciparum, mammarenaviruses, and multidrug-resistant bacteria. Inhibitors of ProRS show efficacy in vitro and in animal models, and resistance mechanisms include amino acid transporter mutations that elevate proline levels.
Cancer and translational control
ProRS is overexpressed in some cancers and supports the high translational demand of tumor cells. Phosphorylation of ProRS may link translation to oncogenic signaling, making it a potential anticancer target.
From proline-tRNA ligase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of ProRS loss on translation and cell viability? | CRISPR knockout of PARS1 or PARS2 in human cell lines |
| How do disease-associated PARS2 mutations affect enzyme function? | Point-mutation knock-in of patient variants in cell lines or mice |
| Can ProRS inhibitors be tested for target engagement? | Tagged knock-in of ProRS with fluorescent or affinity tags |
| Does ProRS overexpression drive oncogenic translation? | Overexpression of wild-type or phospho-mimetic ProRS in cancer cells |
| What is the role of ProRS editing domain in vivo? | Editing-domain point mutants in bacterial or mammalian models |
| How does ProRS inhibition affect pathogen survival? | CRISPR KO of ProRS in P. falciparum or bacteria, followed by inhibitor treatment |
How to Study the proline-tRNA ligase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Aminoacylation assay | Enzyme activity (prolyl-tRNA formation) | Kinetic studies, inhibitor screening |
| Phosphoproteomics | Phosphorylation sites on ProRS | Regulation studies |
| Ribo-seq | Global translation efficiency | Effects of ProRS inhibition on protein synthesis |
| CRISPR knockout screens | Gene essentiality and resistance mechanisms | Identifying modifiers of ProRS inhibitor sensitivity |
| Western blot for ISR markers | ATF4, CHOP, p-eIF2α levels | Assessing stress response to ProRS deficiency |
| In vitro editing assay | Hydrolysis of mischarged tRNA | Fidelity studies of ProRS editing domain |
| Thermal shift assay | Protein-ligand binding | Target engagement of ProRS inhibitors |
| Viral plaque assay | Viral replication | Testing ProRS inhibitors against mammarenaviruses |
Biochemical assays for aminoacylation
Aminoacylation activity is measured by incubating purified ProRS with ATP, L-proline, and tRNA(Pro), then quantifying the formation of L-prolyl-tRNA(Pro) using radiolabeled proline or tRNA. These assays are used to determine kinetic parameters and to test inhibitors.
Phosphorylation analysis
Phosphorylation of ProRS can be studied by metabolic labeling with 32P-orthophosphate, immunoprecipitation with anti-ProRS antibodies, and mass spectrometry. These methods identify phosphorylation sites and their impact on activity.
Ribosome profiling (Ribo-seq)
Ribo-seq measures global translation and can reveal codon-specific effects when ProRS is inhibited or depleted. It is used to assess how reduced proline charging affects translation of proline-rich proteins.
CRISPR screens and drug resistance studies
Genome-wide CRISPR knockout screens can identify genes that mediate resistance or sensitivity to ProRS inhibitors. Such screens have revealed the role of amino acid transporters in proline homeostasis and drug resistance.
How CRISPR Can Be Used to Study GO:0004827 proline-tRNA ligase activity
Knockout
CRISPR knockout of PARS1 or PARS2 in human cell lines abolishes proline-tRNA ligase activity, leading to translation arrest and cell death. These models are used to study the essentiality of ProRS and to validate inhibitors.
Point Mutation
Point mutations identified in patients with PARS2 deficiency can be introduced into cell lines or animal models using CRISPR base editing or homology-directed repair. These models help determine whether specific mutations are loss-of-function or affect editing activity.
Knock-in
Knock-in of tagged ProRS (e.g., GFP or HA) allows visualization and immunoprecipitation of the enzyme. This is useful for studying its subcellular localization, interactions, and phosphorylation status.
Overexpression
Overexpression of wild-type or mutant ProRS in cancer cells can reveal its role in oncogenic translation and drug resistance. Such models are used to test whether ProRS inhibitors overcome resistance.
How EDITGENE Supports proline-tRNA ligase activity Research
Researchers studying proline-tRNA ligase activity-related genes often need to determine whether a candidate gene is causally involved in a specific phenotype, such as drug resistance, developmental defects, or altered translation. EDITGENE provides a comprehensive suite of CRISPR services to generate precisely engineered cell and animal models, enabling rigorous functional validation of GO:0004827-related genes.
Contact EDITGENE today to design your custom CRISPR model for proline-tRNA ligase activity research.
Frequently Asked Questions About proline-tRNA ligase activity
What is proline-tRNA ligase activity?
Proline-tRNA ligase activity (GO:0004827) is the enzyme function that attaches the amino acid L-proline to its transfer RNA, a key step in protein synthesis.
What genes are involved in proline-tRNA ligase activity?
The main genes are PARS1 (cytoplasmic) and PARS2 (mitochondrial) in humans, and PRS in pathogens such as Plasmodium and bacteria.
What diseases are associated with proline-tRNA ligase activity?
Mutations in PARS2 cause developmental delay and seizures; ProRS is also a target for malaria, viral, and bacterial infections.
How is proline-tRNA ligase activity regulated?
It is regulated by phosphorylation and by the integrated stress response, which is activated when mitochondrial ProRS is deficient.
What is the reaction catalyzed by proline-tRNA ligase?
ATP + L-proline + tRNA(Pro) = AMP + diphosphate + L-prolyl-tRNA(Pro).
Why is proline-tRNA synthetase a drug target?
It is essential for pathogen survival and has a distinct active site, allowing selective inhibition of malaria, viruses, and bacteria.
What is the editing domain of prolyl-tRNA synthetase?
It is a separate domain that proofreads and hydrolyzes mischarged tRNA, ensuring accurate translation.
How can I study proline-tRNA ligase activity in the lab?
Common methods include aminoacylation assays, Ribo-seq, phosphoproteomics, and CRISPR knockout models.
What CRISPR models are available for ProRS research?
Knockout, point mutation, knock-in, and overexpression models can be generated in cell lines and animals to study ProRS function.
Is proline-tRNA ligase activity involved in cancer?
ProRS is overexpressed in some cancers and supports high translation rates; phosphorylation may link it to oncogenic signaling.
Conclusion
Proline-tRNA ligase activity (GO:0004827) is a central molecular function in translation, with critical roles in protein synthesis, drug resistance, and human disease. The enzyme ProRS is a validated target for anti-infective therapies and its mutations cause severe neurodevelopmental disorders. Continued research using CRISPR models and advanced omics will further illuminate its regulation and therapeutic potential.
References
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- 2. Witwit H et al.. 2026. Prolyl tRNA Synthetase Is Required for Mammarenavirus Multiplication.. Viruses 18(2) PMID: 41754545
- 3. Arif A et al.. 2017. Experimental approaches for investigation of aminoacyl tRNA synthetase phosphorylation.. Methods 113:72-82 PMID: 27729295
- 4. Tambascia C et al.. 2026. Inhibition of prolyl-tRNA synthetase and efflux pumps as a dual-targeting strategy against multidrug-resistant bacteria.. J Enzyme Inhib Med Chem 41(1):2640718 PMID: 41848420
- 5. Xu M et al.. 2026. Activation of the integrated stress response contributes to developmental delay and seizures caused by mitochondrial prolyl-tRNA synthetase (PARS2) deficiency.. Redox Biol 89:103966 PMID: 41380592
- 6. Pallabothula VSK et al.. 2024. A hit expansion of 3-benzamidopyrazine-2-carboxamide: Toward inhibitors of prolyl-tRNA synthetase with antimycobacterial activity.. Arch Pharm (Weinheim) 357(8):e2400171 PMID: 38710636
- 7. Luo Z et al.. 2025. Development of potent inhibitors targeting bacterial prolyl-tRNA synthetase through fluorine scanning-directed activity tuning.. Eur J Med Chem 291:117647 PMID: 40253792
- 8. Danhart EM et al.. 2017. Conformational and chemical selection by a trans-acting editing domain.. Proc Natl Acad Sci U S A 114(33):E6774-E6783 PMID: 28768811
