GO:0051734 ATP-dependent polynucleotide 5'-hydroxyl-kinase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0051734 describes an enzymatic activity that transfers the gamma-phosphate of ATP to the 5'-hydroxyl terminus of a polynucleotide (DNA or RNA), producing ADP and a 5'-phosphopolynucleotide.
• This end-healing activity is essential for tRNA splicing in yeast and fungi, where it generates the 5'-phosphate required for subsequent ligation steps.
• In bacteria such as Clostridium thermocellum and Deinococcus radiodurans, the kinase domain is often fused to a phosphatase domain, forming a bifunctional end-healing enzyme.
• The catalytic mechanism typically involves two metal ions that activate the 5'-OH for nucleophilic attack on ATP.
• Defects in 5'-kinase activity can impair tRNA maturation and RNA repair, with potential links to human diseases such as cancer and neurodegeneration.
• CRISPR-based knockout, point-mutation, and knock-in models are powerful tools to dissect the physiological roles of this activity in diverse organisms.
Description
ATP-dependent polynucleotide 5'-hydroxyl-kinase activity (GO:0051734) is a molecular function that catalyzes the transfer of the gamma-phosphate from ATP to the 5'-hydroxyl group of a polynucleotide, yielding ADP and a 5'-phosphopolynucleotide. This reaction is a critical step in nucleic acid end-healing and RNA repair pathways, where it prepares broken or immature RNA termini for downstream processing such as ligation. The activity is found in diverse organisms, from bacteriophages to humans, and is often associated with multifunctional enzymes that also possess phosphatase or ligase domains. Researchers study this activity to understand fundamental mechanisms of RNA metabolism, tRNA splicing, and DNA repair, as well as to explore its potential as a target for antifungal or antibacterial therapies.
ATP-dependent polynucleotide 5'-hydroxyl-kinase activity At A Glance
| GO ID | GO:0051734 |
|---|---|
| GO term | ATP-dependent polynucleotide 5'-hydroxyl-kinase activity |
| Ontology | molecular_function |
| Synonym | ATP-dependent polynucleotide kinase activity; polynucleotide kinase activity |
| Definition | Catalysis of the reaction: ATP + 5'-dephosphopolynucleotide = ADP + 5'-phosphopolynucleotide. The polynucleotide may be DNA or RNA. |
| Major function | Phosphorylates the 5'-hydroxyl terminus of DNA or RNA, preparing it for ligation or other processing steps. |
| EC number | 2.7.1.78 (polynucleotide 5'-hydroxyl-kinase) |
| Cofactors | Divalent metal ions (e.g., Mg2+ or Mn2+) are typically required for catalysis. |
| Subcellular location | Nucleus, cytoplasm, or mitochondria depending on the organism and enzyme context. |
What Is GO:0051734?
According to the Gene Ontology, GO:0051734 is defined as the catalysis of the reaction: ATP + 5'-dephosphopolynucleotide = ADP + 5'-phosphopolynucleotide. The polynucleotide substrate may be either DNA or RNA. In other words, this activity adds a phosphate group to the 5'-end of a nucleic acid chain that lacks a 5'-phosphate, using ATP as the phosphate donor. This is a key end-healing modification that can restore the ability of a polynucleotide to participate in ligation or other downstream reactions.
Why Is ATP-dependent polynucleotide 5'-hydroxyl-kinase activity Important in Cell Biology?
ATP-dependent polynucleotide 5'-hydroxyl-kinase activity is essential for maintaining nucleic acid integrity and function. It plays a central role in tRNA splicing, where the 5'-OH generated by endonucleolytic cleavage must be phosphorylated before the two tRNA halves can be ligated. In bacteria, this activity is part of end-healing pathways that repair damaged DNA and RNA, contributing to radioresistance and stress survival. In fungi, the kinase is a component of the tRNA ligase complex, and its inhibition could serve as a target for antifungal drugs. Moreover, defects in RNA repair and processing are increasingly linked to human diseases, including cancer and neurodegenerative disorders, making this activity a subject of intense research.
• Essential for tRNA splicing in yeast and fungi, where it generates the 5'-phosphate required for ligation.
• Involved in DNA and RNA end-healing and repair in bacteria, contributing to radioresistance.
• Catalytic mechanism involves two metal ions, providing a paradigm for phosphoryl transfer.
• Potential antifungal target due to its essential role in pathogenic fungi.
• Links to human diseases such as cancer and neurodegeneration through RNA processing defects.
• Enables reverse genetics studies using CRISPR to dissect its physiological roles.
• Provides a model for understanding bifunctional enzymes with kinase and phosphatase domains.
• Important for biotechnology applications requiring end-labeling or repair of nucleic acids.
What Happens During ATP-dependent polynucleotide 5'-hydroxyl-kinase activity?
Substrate recognition and binding
In simple terms: The enzyme first grabs the broken nucleic acid end and ATP.
The kinase domain recognizes a polynucleotide with a free 5'-hydroxyl group, often generated by endonucleolytic cleavage or damage. It binds the substrate in a cleft that positions the 5'-OH for attack and coordinates ATP via conserved residues. In tRNA splicing, the substrate is a tRNA half-molecule with a 5'-OH terminus.
Metal ion coordination and activation
In simple terms: Metal ions help the enzyme perform the chemical reaction.
Divalent metal ions, typically Mg2+ or Mn2+, are essential for catalysis. They activate the 5'-hydroxyl group for nucleophilic attack and stabilize the transition state. Structural studies of fungal tRNA ligase and bacterial Pnk reveal a two-metal-ion mechanism.
Phosphoryl transfer from ATP
In simple terms: The enzyme moves a phosphate from ATP onto the nucleic acid end.
The gamma-phosphate of ATP is transferred to the 5'-OH of the polynucleotide, forming a 5'-phosphopolynucleotide and ADP. This reaction is reversible in vitro but proceeds forward under cellular conditions. The kinase domain shares structural homology with other P-loop kinases.
Product release and downstream processing
In simple terms: After adding the phosphate, the enzyme lets go, and the nucleic acid is ready for the next step.
The phosphorylated polynucleotide is released and can then serve as a substrate for ligation or other processing enzymes. In tRNA splicing, the 5'-phosphate is required for the ligase step that joins the tRNA halves. In DNA repair, the 5'-phosphate can be sealed by DNA ligase.
Key Genes Involved in GO:0051734 ATP-dependent polynucleotide 5'-hydroxyl-kinase activity
The following genes and proteins are experimentally characterized to possess or regulate ATP-dependent polynucleotide 5'-hydroxyl-kinase activity.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TRL1 (yeast) | Bifunctional tRNA ligase with kinase and cyclic phosphodiesterase domains | Model for tRNA splicing and end-healing |
| TRI1 (Candida albicans) | tRNA ligase with kinase activity | Antifungal target |
| Pnk (Clostridium thermocellum) | Polynucleotide kinase-phosphatase | Bacterial RNA repair model |
| HD-Pnk (Runella slithyformis) | Bifunctional kinase-phosphatase | Structural and mechanistic studies |
| DraPnk (Deinococcus radiodurans) | Polynucleotide kinase involved in DNA repair | Radioresistance model |
| LIG1 (yeast) | tRNA ligase with GTP-dependent splicing | Alternative splicing mechanism |
| Mucorales tRNA ligase | RNA 5'-OH kinase and ligase | Pathogenic fungi target |
| Clp1 (human) | mRNA 3'-end processing and tRNA splicing | Potential disease link |
| RLIG1 (human) | tRNA ligase complex component | tRNA splicing and disease |
| PNKP (human) | Polynucleotide kinase 3'-phosphatase | DNA repair and neurodegeneration |
| TRL1 homologs in fungi | tRNA splicing | Antifungal development |
| Bacteriophage T4 Pnk | Classic polynucleotide kinase | Biochemical tool |
| Archaeal Pnk | RNA repair | Evolutionary studies |
| Plant tRNA ligase | tRNA splicing | Plant development |
| Drosophila tRNA ligase | tRNA splicing | Developmental genetics |
| C. elegans tRNA ligase | tRNA splicing | RNAi studies |
How Is ATP-dependent polynucleotide 5'-hydroxyl-kinase activity Regulated?
The activity of ATP-dependent polynucleotide 5'-hydroxyl-kinase is regulated at multiple levels. In yeast, the kinase domain of Trl1 is activated by autophosphorylation and by interaction with other tRNA splicing factors. In bacteria, expression of Pnk is induced under stress conditions such as DNA damage, and its activity is modulated by the associated phosphatase domain. In pathogenic fungi, the kinase is essential for tRNA splicing and its expression is tightly linked to growth and virulence. Additionally, post-translational modifications and subcellular localization may influence its function, though specific regulatory mechanisms remain to be fully elucidated.
ATP-dependent polynucleotide 5'-hydroxyl-kinase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| TRL1 (Candida albicans) | Fungal virulence | KO in C. albicans; mouse infection model |
| Mucorales tRNA ligase | Mucormycosis | KO in Mucorales; antifungal testing |
| PNKP (human) | Microcephaly, neurodegeneration | Patient iPSC-derived neurons; KO mice |
| CLP1 (human) | Neurodegeneration | Knock-in mice; patient cells |
| RLIG1 (human) | Cancer | Overexpression in cancer cell lines; xenografts |
Fungal infections
The tRNA splicing kinase is essential for the viability of pathogenic fungi such as Candida albicans and Mucorales species. Inhibition of this activity could provide a novel antifungal strategy, as human cells lack a direct ortholog of the fungal tRNA ligase.
Cancer
Dysregulation of tRNA splicing and RNA repair pathways has been implicated in cancer. Overexpression of tRNA ligase components, including the kinase, may contribute to tumorigenesis by altering the tRNA pool and translation.
Neurodegeneration
Mutations in human PNKP, which possesses a related 5'-kinase activity, cause microcephaly and neurodegeneration. This highlights the importance of end-healing enzymes in neuronal development and maintenance.
From ATP-dependent polynucleotide 5'-hydroxyl-kinase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is the kinase essential for tRNA splicing? | CRISPR KO of TRL1 in yeast |
| What is the catalytic mechanism? | Point mutations in catalytic residues; in vitro assays |
| Does the kinase affect virulence? | KO in Candida albicans; mouse infection |
| Can the kinase be targeted for antifungal therapy? | Knock-in of resistance mutations; drug screens |
| What is the role in DNA repair? | KO in Deinococcus radiodurans; radiation sensitivity |
| How is the kinase regulated? | Tagged knock-in for localization and interaction studies |
How to Study the ATP-dependent polynucleotide 5'-hydroxyl-kinase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Kinase assay with gamma-32P-ATP | Phosphorylation of 5'-OH polynucleotide | Enzyme kinetics and inhibitor testing |
| X-ray crystallography | Three-dimensional structure | Mechanistic studies and drug design |
| CRISPR knockout | Gene essentiality and phenotype | Functional genomics in yeast and fungi |
| tRNA sequencing | tRNA splicing efficiency | Analysis of tRNA processing defects |
| RNA-seq | Global gene expression changes | Transcriptome-wide effects of kinase loss |
| Western blot | Protein expression and modification | Validation of knock-in tags |
| Radiation sensitivity assay | DNA repair capacity | Bacterial end-healing studies |
| Fluorescence microscopy | Subcellular localization | Live-cell imaging of tagged kinase |
Biochemical kinase assays
In vitro kinase assays using synthetic polynucleotides with 5'-OH termini and gamma-32P-ATP are standard for measuring activity. These assays can be coupled with thin-layer chromatography or gel electrophoresis to detect the phosphorylated product.
Structural biology
X-ray crystallography and cryo-EM have revealed the atomic details of the kinase domain, including metal ion coordination and ATP binding. Such studies inform inhibitor design and mechanistic understanding.
Genetic knockout and knockdown
CRISPR-Cas9 knockout of the kinase gene in model organisms (yeast, fungi, bacteria) allows assessment of its essentiality and phenotypic consequences, such as tRNA splicing defects or radiation sensitivity.
RNA sequencing and tRNA profiling
RNA-seq and specialized tRNA sequencing can detect accumulation of unspliced tRNA precursors or changes in tRNA abundance upon loss of kinase activity, linking the enzyme to global RNA metabolism.
How CRISPR Can Be Used to Study GO:0051734 ATP-dependent polynucleotide 5'-hydroxyl-kinase activity
Knockout
CRISPR-Cas9 knockout of the gene encoding the 5'-kinase (e.g., TRL1 in yeast or Pnk in bacteria) can reveal its essentiality and role in tRNA splicing or DNA repair. Such models are valuable for identifying synthetic lethal interactions and potential drug targets.
Point Mutation
Introducing point mutations in catalytic residues (e.g., aspartates coordinating metal ions) via CRISPR can dissect the enzymatic mechanism and separate kinase activity from other domains. These models help confirm the two-metal-ion mechanism.
Knock-in
Knock-in of epitope tags (e.g., FLAG, GFP) at the endogenous locus allows for localization, interaction, and stability studies under native regulation. This is particularly useful for understanding the spatiotemporal dynamics of the kinase.
Overexpression
CRISPR activation or cDNA overexpression can be used to study gain-of-function phenotypes, such as increased tRNA splicing or enhanced DNA repair. Overexpression models are also useful for producing recombinant enzyme for structural studies.
How EDITGENE Supports ATP-dependent polynucleotide 5'-hydroxyl-kinase activity Research
Researchers studying ATP-dependent polynucleotide 5'-hydroxyl-kinase activity-related genes often need to determine whether a candidate gene is causally involved in tRNA splicing, RNA repair, or disease. EDITGENE provides a comprehensive suite of CRISPR services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for ATP-dependent polynucleotide 5'-hydroxyl-kinase activity research.
Frequently Asked Questions About ATP-dependent polynucleotide 5'-hydroxyl-kinase activity
What is ATP-dependent polynucleotide 5'-hydroxyl-kinase activity?
It is an enzymatic activity (GO:0051734) that transfers a phosphate from ATP to the 5'-hydroxyl end of DNA or RNA, preparing it for ligation or other processing.
What genes are involved in ATP-dependent polynucleotide 5'-hydroxyl-kinase activity?
Key genes include TRL1 in yeast, Pnk in bacteria, and PNKP in humans, among others.
What is the role of this kinase in tRNA splicing?
It phosphorylates the 5'-OH of tRNA halves generated by endonucleolytic cleavage, enabling their ligation by tRNA ligase.
Which diseases are linked to defects in this activity?
Defects in related enzymes are linked to fungal infections, cancer, and neurodegeneration.
How can I study this activity using CRISPR?
CRISPR knockout, point mutation, knock-in, and overexpression models allow functional dissection in various organisms.
What is the catalytic mechanism?
It involves two metal ions that activate the 5'-OH for attack on ATP's gamma-phosphate.
Is this activity found in humans?
Yes, human PNKP possesses a related 5'-kinase activity involved in DNA repair.
What are the synonyms for this GO term?
Synonyms include ATP-dependent polynucleotide kinase activity and polynucleotide kinase activity.
What model organisms are used to study it?
Yeast, fungi, bacteria, and human cell lines are commonly used.
What methods measure this activity?
In vitro kinase assays with gamma-32P-ATP, structural biology, and genetic knockouts are standard.
Conclusion
ATP-dependent polynucleotide 5'-hydroxyl-kinase activity (GO:0051734) is a fundamental enzymatic function that repairs and prepares nucleic acid ends for essential processes such as tRNA splicing and DNA repair. Its presence in diverse organisms, from bacteria to humans, underscores its biological importance. Continued research using CRISPR models and biochemical assays will further illuminate its mechanisms and potential as a therapeutic target.
References
- 1. Banerjee A et al.. 2019. Structure and two-metal mechanism of fungal tRNA ligase.. Nucleic Acids Res 47(3):1428-1439 PMID: 30590734
- 2. Sawaya R et al.. 2003. Genetic and biochemical analysis of the functional domains of yeast tRNA ligase.. J Biol Chem 278(45):43928-38 PMID: 12933796
- 3. Ghosh S et al.. 2024. Identification, characterization, and structure of a tRNA splicing enzyme RNA 5'-OH kinase from the pathogenic fungi Mucorales.. RNA 30(12):1674-1685 PMID: 39357987
- 4. Ghosh S et al.. 2024. Characterization of tRNA splicing enzymes RNA ligase and tRNA 2'-phosphotransferase from the pathogenic fungi Mucorales.. RNA 30(4):367-380 PMID: 38238085
- 5. Keppetipola N et al.. 2006. Mechanism of the phosphatase component of Clostridium thermocellum polynucleotide kinase-phosphatase.. RNA 12(1):73-82 PMID: 16301605
- 6. Munir A et al.. 2019. Structure-Function Analysis of the Phosphoesterase Component of the Nucleic Acid End-Healing Enzyme Runella slithyformis HD-Pnk.. J Bacteriol 201(16) PMID: 31160396
- 7. Blasius M et al.. 2007. Enzymes involved in DNA ligation and end-healing in the radioresistant bacterium Deinococcus radiodurans.. BMC Mol Biol 8:69 PMID: 17705817
- 8. Westaway SK et al.. 1993. Novel activity of a yeast ligase deletion polypeptide. Evidence for GTP-dependent tRNA splicing.. J Biol Chem 268(4):2435-43 PMID: 8428918
