GO:0051731 polynucleotide 5'-hydroxyl-kinase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0051731 (polynucleotide 5'-hydroxyl-kinase activity) catalyzes the transfer of a gamma-phosphate from an NTP to the 5'-hydroxyl terminus of DNA or RNA, producing an NDP and a 5'-phosphopolynucleotide.
• The best-characterized enzyme carrying this activity is T4 polynucleotide kinase (T4 PNK), which also possesses an intrinsic 3'-phosphatase activity that removes 3'-phosphate groups to generate ligatable ends.
• In eukaryotes, polynucleotide 5'-kinase activity is required for ribosomal RNA processing; the human protein Nol9 is a nuclear polynucleotide 5'-kinase involved in 5.8S and 28S rRNA maturation.
• A ligase-associated 5'-hydroxyl polynucleotide kinase activity was purified from wheat germ, indicating that this activity also participates in plant RNA ligation pathways.
• HeLa cell nuclei contain a 5'-hydroxyl polyribonucleotide kinase that phosphorylates the 5'-termini of RNA molecules, suggesting a role in nuclear RNA metabolism.
• Because the reaction generates a 5'-phosphate, this activity is essential for preparing RNA or DNA ends for downstream ligation, making it a key tool in molecular cloning and a target for biosensor development.
Description
Polynucleotide 5'-hydroxyl-kinase activity (GO:0051731) is a molecular function that enables the phosphorylation of the 5'-hydroxyl terminus of a polynucleotide chain, using an NTP as the phosphate donor and releasing an NDP. This activity is chemically distinct from protein kinases because its substrate is a nucleic acid polymer rather than a polypeptide, and it can act on both DNA and RNA molecules. The reaction is fundamental to nucleic acid end-joining and processing pathways, as it converts a 5'-OH end into a 5'-phosphate, which is a prerequisite for ligation by DNA or RNA ligases. The most extensively studied enzyme with this activity is T4 polynucleotide kinase (T4 PNK), a bifunctional enzyme that also carries a 3'-phosphatase domain capable of removing 3'-phosphate groups. In eukaryotes, a nuclear polynucleotide 5'-kinase named Nol9 was identified in humans and shown to be required for processing of ribosomal RNA precursors. A separate 5'-hydroxyl polyribonucleotide kinase was purified from HeLa cell nuclei, indicating that mammalian cells possess dedicated enzymes for RNA 5'-phosphorylation. In plants, a ligase-associated 5'-hydroxyl polynucleotide kinase activity was characterized from wheat germ, linking this activity to RNA ligation. Researchers study GO:0051731 because it sits at the interface of nucleic acid repair, RNA processing, and molecular tool development. The activity is routinely exploited in cloning workflows to phosphorylate synthetic oligonucleotides before ligation, and it is a target for sensitive electrochemical biosensors that detect kinase activity for diagnostic and drug-discovery applications. Understanding its enzymology, regulation, and cellular roles is therefore relevant to basic RNA biology, genome engineering, and assay development.
polynucleotide 5'-hydroxyl-kinase activity At A Glance
| GO ID | GO:0051731 |
|---|---|
| GO term | polynucleotide 5'-hydroxyl-kinase activity |
| Ontology | molecular_function |
| Synonym | 5'-dephosphopolynucleotide kinase activity; 5'-hydroxyl polynucleotide kinase activity; PNK; polynucleotide 5'-hydroxy-kinase activity; polynucleotide 5'-hydroxyl kinase (phosphorylating) activity; polynucleotide kinase activity |
| Major function | Phosphorylates the 5'-hydroxyl terminus of DNA or RNA using an NTP as phosphate donor, generating a 5'-phosphopolynucleotide and an NDP. |
| Reaction | NTP + 5'-dephosphopolynucleotide = NDP + 5'-phosphopolynucleotide |
| Substrate | Polynucleotide with a free 5'-hydroxyl group; can be DNA or RNA. |
| Representative enzyme | T4 polynucleotide kinase (T4 PNK), a bifunctional enzyme with 5'-kinase and 3'-phosphatase activities. |
| Eukaryotic example | Human Nol9, a nuclear polynucleotide 5'-kinase involved in rRNA processing. |
What Is GO:0051731?
Polynucleotide 5'-hydroxyl-kinase activity is defined as the catalysis of the reaction: NTP + 5'-dephosphopolynucleotide = NDP + 5'-phosphopolynucleotide. In this reaction, the enzyme transfers the terminal (gamma) phosphate of a nucleoside triphosphate to the 5'-hydroxyl group of a polynucleotide, which may be either DNA or RNA. The product is a polynucleotide bearing a 5'-phosphate and a nucleoside diphosphate byproduct. This activity is synonymous with 5'-dephosphopolynucleotide kinase activity, 5'-hydroxyl polynucleotide kinase activity, PNK, polynucleotide 5'-hydroxy-kinase activity, polynucleotide 5'-hydroxyl kinase (phosphorylating) activity, and polynucleotide kinase activity.
Why Is polynucleotide 5'-hydroxyl-kinase activity Important in Cell Biology?
Polynucleotide 5'-hydroxyl-kinase activity is important because it creates the 5'-phosphate ends that are required for nucleic acid ligation, a step that is central to DNA repair, RNA processing, and molecular cloning. In eukaryotes, the activity is linked to ribosome biogenesis through Nol9, which is required for processing of ribosomal RNA precursors. In mammalian nuclei, a 5'-hydroxyl polyribonucleotide kinase was purified from HeLa cells, indicating a role in RNA metabolism. The activity is also a practical target in biotechnology: it is used to label and phosphorylate oligonucleotides, and it is detected by electrochemical biosensors that exploit host-guest recognition for sensitive kinase assays. These features make GO:0051731 relevant to RNA biology, genome maintenance, and assay development.
• Provides 5'-phosphate ends required for DNA and RNA ligation reactions.
• Supports ribosomal RNA processing in eukaryotes through the Nol9 kinase.
• Contributes to nuclear RNA metabolism, as shown by a HeLa nuclear 5'-hydroxyl polyribonucleotide kinase.
• Enables end-labeling and phosphorylation of synthetic oligonucleotides in molecular biology workflows.
• Serves as a detection target for electrochemical biosensors based on host-guest recognition.
• Can be monitored using rolling circle amplification strategies coupled to magnetic nanoparticles.
• Links nucleic acid end chemistry to plant RNA ligation pathways via a wheat germ ligase-associated kinase.
• Represents a bifunctional enzyme model where 5'-kinase and 3'-phosphatase activities cooperate to prepare ligatable ends.
• Offers a molecular function node for annotating gene products involved in polynucleotide end processing.
• Is relevant to assay development for kinase inhibitors and nucleic acid modifying enzymes.
Molecular Mechanism of polynucleotide 5'-hydroxyl-kinase activity
Substrate recognition and binding
In simple terms: The enzyme first grabs the end of a DNA or RNA strand that has a free 5'-OH group.
Polynucleotide 5'-hydroxyl-kinase activity acts on polynucleotides that carry a 5'-hydroxyl terminus, and the substrate can be either DNA or RNA. The enzyme must recognize the terminal nucleotide and position the 5'-OH for attack on the gamma-phosphate of an NTP. T4 polynucleotide kinase is the classical enzyme used to study this step, and its ability to act on both DNA and RNA substrates has been documented. A 5'-hydroxyl polyribonucleotide kinase purified from HeLa cell nuclei also phosphorylates RNA 5'-termini, confirming that RNA is a bona fide substrate in mammalian cells.
Phosphoryl transfer from NTP to the 5'-hydroxyl
In simple terms: The enzyme moves a phosphate from an energy-rich NTP onto the end of the nucleic acid.
The catalytic step follows the reaction NTP + 5'-dephosphopolynucleotide = NDP + 5'-phosphopolynucleotide, in which the gamma-phosphate of the NTP is transferred to the 5'-OH of the polynucleotide. This produces a 5'-phosphopolynucleotide and an NDP byproduct. The reaction is chemically analogous to the phosphorylation step catalyzed by T4 polynucleotide kinase, which has been characterized in detail. The wheat germ ligase-associated 5'-hydroxyl polynucleotide kinase activity also catalyzes this type of phosphoryl transfer, linking it to RNA ligation.
Bifunctional 3'-phosphatase cooperation in T4 PNK
In simple terms: Some enzymes also remove a phosphate from the other end so the nucleic acid can be joined.
T4 polynucleotide kinase is bifunctional: in addition to its 5'-kinase activity, it carries a 3'-phosphatase activity that removes 3'-phosphate groups. This combination is useful because ligases require a 5'-phosphate and a 3'-hydroxyl, so the 3'-phosphatase helps generate a ligatable 3'-OH while the 5'-kinase installs the 5'-phosphate. The 3'-phosphatase activity of T4 polynucleotide kinase was characterized biochemically, establishing the enzyme as a model for coupled end-processing reactions.
Eukaryotic polynucleotide 5'-kinases and rRNA processing
In simple terms: Human cells have their own version of this enzyme that helps build ribosomes.
Nol9 is a novel polynucleotide 5'-kinase involved in ribosomal RNA processing in human cells. It localizes to the nucleus and is required for the maturation of ribosomal RNA precursors, connecting GO:0051731 to ribosome biogenesis. Separately, a 5'-hydroxyl polyribonucleotide kinase was purified from HeLa cell nuclei, demonstrating that mammalian nuclei contain enzymes dedicated to RNA 5'-phosphorylation. Together, these findings show that polynucleotide 5'-kinase activity is not restricted to bacteriophage enzymes but is embedded in eukaryotic RNA metabolism.
Assay and detection chemistry
In simple terms: Scientists can measure this activity with electrochemical sensors that change signal when phosphate is added.
Electrochemical biosensors have been developed to detect T4 polynucleotide kinase activity based on host-guest recognition between phosphate pillararene and methylene blue. Related platforms use phosphate pillararene@MWCNTs and thionine, or phosphate pillararene@palladium nanoparticles@reduced graphene oxide with toluidine blue. A magnetic Fe3O4@TiO2 nanoparticle-triggered rolling circle amplification strategy has also been used for electrochemical detection of T4 polynucleotide kinase activity. These assays exploit the generation of 5'-phosphate products to produce measurable signals, providing practical readouts for GO:0051731.
Key Genes Involved in GO:0051731 polynucleotide 5'-hydroxyl-kinase activity
The following genes and proteins are experimentally linked to polynucleotide 5'-hydroxyl-kinase activity or its detection.
| Gene | Major Role | Research Relevance |
|---|---|---|
| T4 PNK (bacteriophage T4 polynucleotide kinase) | Bifunctional 5'-kinase and 3'-phosphatase that prepares DNA ends for ligation | Classical model enzyme for GO:0051731; widely used in cloning and biosensor assays |
| NOL9 (human Nol9) | Nuclear polynucleotide 5'-kinase involved in ribosomal RNA processing | Links GO:0051731 to eukaryotic ribosome biogenesis and rRNA maturation |
| HeLa nuclear 5'-hydroxyl polyribonucleotide kinase | Phosphorylates 5'-termini of RNA in HeLa cell nuclei | Provides evidence for a mammalian RNA-specific polynucleotide kinase |
| Wheat germ RNA ligase-associated 5'-hydroxyl polynucleotide kinase | Ligase-associated kinase activity that phosphorylates polynucleotide 5'-ends | Connects GO:0051731 to plant RNA ligation pathways |
| T4 PNK 3'-phosphatase domain | Removes 3'-phosphate groups to generate ligatable 3'-OH ends | Model for bifunctional end-processing enzymes |
| T4 PNK 5'-kinase domain | Transfers gamma-phosphate from NTP to 5'-OH of DNA or RNA | Core catalytic module for GO:0051731 |
| Nol9-associated rRNA precursors | Substrates of Nol9 5'-kinase during rRNA processing | Readout for Nol9 function in ribosome biogenesis |
| HeLa nuclear RNA substrates | RNA molecules with 5'-hydroxyl termini phosphorylated by nuclear kinase | Substrate context for mammalian RNA 5'-phosphorylation |
| Wheat germ RNA ligase | Ligase that partners with the associated 5'-kinase activity | Model for coupled kinase-ligase RNA processing |
| T4 PNK biosensor recognition element (phosphate pillararene) | Host-guest recognition component in electrochemical detection | Enables sensitive detection of T4 PNK activity |
| Magnetic Fe3O4@TiO2 nanoparticles | Capture and amplification platform for T4 PNK detection | Supports rolling circle amplification-based assays |
| Methylene blue | Electrochemical reporter in T4 PNK biosensor | Signal readout for kinase activity |
| Thionine | Electrochemical reporter in T4 PNK biosensor | Signal readout for kinase activity |
| Toluidine blue | Electrochemical reporter in T4 PNK biosensor | Signal readout for kinase activity |
| MWCNTs (multi-walled carbon nanotubes) | Electrode material enhancing biosensor performance | Improves sensitivity of T4 PNK detection |
| Palladium nanoparticles@reduced graphene oxide | Nanocomposite electrode material for T4 PNK biosensor | Enhances electrochemical signal |
| Rolling circle amplification products | Amplified DNA products triggered by T4 PNK activity | Amplification strategy for sensitive detection |
How Is polynucleotide 5'-hydroxyl-kinase activity Regulated?
Polynucleotide 5'-hydroxyl-kinase activity is regulated at the level of enzyme availability and substrate accessibility. In human cells, Nol9 is a nuclear polynucleotide 5'-kinase required for ribosomal RNA processing, so its function is tied to the transcriptional and assembly state of the ribosome biogenesis machinery. The presence of a distinct 5'-hydroxyl polyribonucleotide kinase in HeLa cell nuclei indicates that RNA 5'-phosphorylation is compartmentalized and likely coupled to nuclear RNA metabolism. In plants, the wheat germ 5'-hydroxyl polynucleotide kinase activity copurifies with RNA ligase, suggesting that it is regulated in the context of a ligase complex. For T4 polynucleotide kinase, the 5'-kinase and 3'-phosphatase activities are intrinsic to the same polypeptide, so the overall end-processing outcome depends on the balance of these two catalytic activities. No specific small-molecule or post-translational regulators of GO:0051731 were identified in the verified citations, so regulation is best described in terms of enzyme complex context and substrate availability.
polynucleotide 5'-hydroxyl-kinase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NOL9 | Ribosome biogenesis and rRNA processing defects | NOL9 knockout or point-mutation cell lines with rRNA processing readouts |
| T4 PNK (bacteriophage T4 polynucleotide kinase) | Nucleic acid end-processing model | Recombinant enzyme assays and biosensor validation |
| HeLa nuclear 5'-hydroxyl polyribonucleotide kinase | Nuclear RNA metabolism | Nuclear extract assays and RNA 5'-phosphorylation profiling |
| Wheat germ RNA ligase-associated kinase | Plant RNA ligation pathways | Plant ligase-kinase complex purification and activity assays |
| T4 PNK biosensor platforms | Kinase detection and inhibitor screening | Electrochemical assay development and validation |
Ribosomopathies and rRNA processing defects
Nol9 is a human polynucleotide 5'-kinase involved in ribosomal RNA processing, and its activity is required for normal maturation of rRNA precursors. Because ribosome biogenesis is essential for cell growth, defects in Nol9-dependent 5'-phosphorylation could contribute to ribosomopathy-like phenotypes characterized by impaired rRNA processing. The existence of a separate HeLa nuclear 5'-hydroxyl polyribonucleotide kinase further supports the idea that RNA 5'-phosphorylation is a dedicated step in nuclear RNA metabolism that, when perturbed, may affect ribosome production.
Nucleic acid end-processing and genome stability
The 5'-kinase reaction generates 5'-phosphate ends that are required for ligation, a chemical step shared with DNA repair and RNA joining pathways. T4 polynucleotide kinase is the archetypal enzyme for this activity and is used experimentally to prepare ligatable ends, illustrating how loss of 5'-phosphorylation would block downstream joining reactions. In plants, a ligase-associated 5'-hydroxyl polynucleotide kinase activity was purified from wheat germ, showing that coupling between 5'-phosphorylation and ligation is conserved in RNA processing. These observations imply that defects in polynucleotide 5'-kinase activity could impair nucleic acid end-joining and compromise genome or transcript stability.
Cancer and kinase-targeted assay development
Kinases are common targets in cancer research, and polynucleotide 5'-hydroxyl-kinase activity has attracted attention as an analyte for sensitive detection platforms. Electrochemical biosensors based on host-guest recognition have been developed to measure T4 polynucleotide kinase activity, providing tools that could be adapted to screen for inhibitors or to detect kinase activity in biological samples. A magnetic nanoparticle-triggered rolling circle amplification strategy further extends the sensitivity of such assays. Although the verified citations do not establish a direct causal role for GO:0051731 in a specific human cancer, these assay platforms support research into kinase activity as a biomarker or drug-discovery target.
From polynucleotide 5'-hydroxyl-kinase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of NOL9 abolish polynucleotide 5'-kinase-dependent rRNA processing? | NOL9 knockout human cell line with rRNA processing assays |
| Which residues are required for 5'-kinase catalysis? | Point-mutation knock-in of catalytic residues in T4 PNK or NOL9 |
| Can a tagged kinase be used to map substrate RNAs? | Tagged knock-in of NOL9 or nuclear RNA kinase for pulldown and sequencing |
| Does overexpression of a polynucleotide 5'-kinase alter RNA end profiles? | Overexpression cell model with RNA 5'-end sequencing |
| Can biosensors detect kinase activity in complex samples? | Electrochemical biosensor platforms using T4 PNK as analyte |
| Is the ligase-associated kinase activity required for RNA ligation? | Knockout or point-mutation of the wheat germ ligase-associated kinase |
How to Study the polynucleotide 5'-hydroxyl-kinase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Biochemical kinase assay | Transfer of gamma-phosphate from NTP to 5'-OH polynucleotide | Enzyme characterization and GO annotation |
| 3'-Phosphatase assay | Removal of 3'-phosphate groups by bifunctional enzymes | Analysis of T4 PNK end-processing |
| Electrochemical biosensor with methylene blue | T4 PNK activity via host-guest recognition | Sensitive kinase detection |
| Electrochemical biosensor with thionine | T4 PNK activity using MWCNT platform | Kinase assay development |
| Electrochemical biosensor with toluidine blue | T4 PNK activity using PdNP@rGO nanocomposite | Signal-enhanced detection |
| Rolling circle amplification assay | T4 PNK activity triggered by magnetic nanoparticles | Amplified electrochemical detection |
| rRNA processing assay | Maturation of rRNA precursors dependent on Nol9 | Ribosome biogenesis studies |
| RNA ligation assay | Ligase-associated 5'-kinase activity in wheat germ | Plant RNA processing research |
Biochemical kinase assays
Classical characterization of polynucleotide 5'-hydroxyl-kinase activity uses purified enzymes and defined polynucleotide substrates to measure phosphate transfer from NTP to 5'-OH ends. T4 polynucleotide kinase was characterized in this way, including its associated 3'-phosphatase activity. The HeLa nuclear 5'-hydroxyl polyribonucleotide kinase was purified and its properties determined using similar biochemical approaches. These assays remain the gold standard for assigning GO:0051731 to a gene product.
Electrochemical biosensor detection
Electrochemical biosensors provide sensitive readouts of T4 polynucleotide kinase activity based on host-guest recognition between phosphate pillararene and redox reporters such as methylene blue, thionine, or toluidine blue. A magnetic Fe3O4@TiO2 nanoparticle-triggered rolling circle amplification strategy has also been used for electrochemical detection of T4 polynucleotide kinase activity. These methods are useful for quantifying kinase activity in vitro and for developing inhibitor screening platforms.
Ribosomal RNA processing analysis
Because Nol9 is a polynucleotide 5'-kinase involved in ribosomal RNA processing, rRNA maturation assays such as northern blotting or RNA sequencing of rRNA precursors can be used to monitor its function. Loss-of-function studies of Nol9 reveal defects in rRNA processing, providing a direct readout for the biological role of GO:0051731 in ribosome biogenesis. These approaches connect the molecular function to a cellular process.
RNA 5'-end mapping and ligation assays
The 5'-phosphate generated by polynucleotide 5'-kinase activity is required for ligation, so ligation-based assays can be used to detect the reaction product. In plants, the wheat germ RNA ligase-associated 5'-hydroxyl polynucleotide kinase activity was characterized in the context of RNA ligation, providing a model for coupled kinase-ligase assays. In mammalian nuclei, the HeLa 5'-hydroxyl polyribonucleotide kinase provides a system for studying RNA 5'-phosphorylation and downstream joining.
How CRISPR Can Be Used to Study GO:0051731 polynucleotide 5'-hydroxyl-kinase activity
Knockout
CRISPR knockout of NOL9 can be used to test whether loss of the polynucleotide 5'-kinase abolishes ribosomal RNA processing, providing causal evidence for GO:0051731 in ribosome biogenesis. Knockout of the wheat germ ligase-associated kinase or its homologs can similarly test the role of 5'-phosphorylation in RNA ligation pathways. In general, knockout models are the first step to determine whether a candidate gene is required for polynucleotide 5'-kinase-dependent processes.
Point Mutation
Point mutations in the catalytic domain of T4 polynucleotide kinase or NOL9 can separate 5'-kinase activity from 3'-phosphatase activity or from other functions. Such mutants allow researchers to test which residues are essential for phosphoryl transfer from NTP to the 5'-OH terminus. Point-mutation models are especially useful when a gene has multiple domains, as is the case for bifunctional T4 PNK.
Knock-in
Knock-in of epitope tags or fluorescent tags into NOL9 or other polynucleotide 5'-kinase genes enables localization and interactome studies. Tagged knock-in models can be used to purify the kinase and identify its RNA substrates, linking GO:0051731 to specific RNA processing events. Knock-in of disease-associated or catalytic variants can also be used to model functional consequences in a physiological context.
Overexpression
Overexpression of a polynucleotide 5'-kinase can be used to amplify its activity for biochemical assays or to test whether excess 5'-phosphorylation alters RNA end profiles. Overexpression models are also useful for producing recombinant enzyme for biosensor development and inhibitor screening. In mammalian cells, overexpression of a nuclear RNA kinase can reveal effects on RNA metabolism that are masked at endogenous levels.
How EDITGENE Supports polynucleotide 5'-hydroxyl-kinase activity Research
Researchers studying polynucleotide 5'-hydroxyl-kinase activity-related genes often need to determine whether a candidate gene is causally involved in nucleic acid end processing, rRNA maturation, or RNA ligation. Establishing causality requires precise genetic models that can remove, modify, or tag the enzyme without confounding off-target effects. EDITGENE provides CRISPR-based cell model services tailored to these needs, from knockout to knock-in and overexpression, supported by library screening and bioinformatics.
Contact EDITGENE today to design your custom CRISPR model for polynucleotide 5'-hydroxyl-kinase activity research.
Frequently Asked Questions About polynucleotide 5'-hydroxyl-kinase activity
What is polynucleotide 5'-hydroxyl-kinase activity?
It is a molecular function (GO:0051731) that catalyzes the transfer of a phosphate from an NTP to the 5'-hydroxyl end of DNA or RNA, producing a 5'-phosphopolynucleotide and an NDP.
What is the reaction catalyzed by GO:0051731?
The reaction is NTP + 5'-dephosphopolynucleotide = NDP + 5'-phosphopolynucleotide, and the polynucleotide can be DNA or RNA.
What genes are involved in polynucleotide 5'-hydroxyl-kinase activity?
Key examples include bacteriophage T4 polynucleotide kinase (T4 PNK), human NOL9, a HeLa nuclear 5'-hydroxyl polyribonucleotide kinase, and a wheat germ ligase-associated 5'-hydroxyl polynucleotide kinase.
What is T4 polynucleotide kinase?
T4 polynucleotide kinase is a bifunctional enzyme with 5'-kinase and 3'-phosphatase activities that prepares DNA or RNA ends for ligation.
What is the role of Nol9 in rRNA processing?
Nol9 is a human polynucleotide 5'-kinase involved in ribosomal RNA processing, and its activity is required for normal maturation of rRNA precursors.
How is polynucleotide 5'-hydroxyl-kinase activity detected?
It can be detected by biochemical kinase assays and by electrochemical biosensors using host-guest recognition with reporters such as methylene blue, thionine, or toluidine blue.
Why is 5'-phosphorylation important for ligation?
Ligases require a 5'-phosphate and a 3'-hydroxyl to join nucleic acids, so 5'-phosphorylation by GO:0051731 creates a ligatable end.
Is polynucleotide 5'-hydroxyl-kinase activity found in eukaryotes?
Yes, human Nol9 is a nuclear polynucleotide 5'-kinase involved in rRNA processing, and a 5'-hydroxyl polyribonucleotide kinase was purified from HeLa cell nuclei.
What is the difference between 5'-kinase and 3'-phosphatase activity?
5'-kinase adds a phosphate to a 5'-OH end, while 3'-phosphatase removes a phosphate from a 3'-phosphate end; T4 PNK has both activities.
How can CRISPR help study polynucleotide 5'-hydroxyl-kinase activity?
CRISPR knockout, point mutation, knock-in, and overexpression models can test the causal role of kinase genes in rRNA processing, RNA ligation, and nucleic acid end metabolism.
Conclusion
Polynucleotide 5'-hydroxyl-kinase activity (GO:0051731) is a molecular function that installs 5'-phosphate groups on DNA or RNA, creating ends that are essential for ligation and downstream processing. Its best-known enzyme, T4 polynucleotide kinase, is bifunctional and serves as a model for coupled 5'-kinase and 3'-phosphatase activities. In eukaryotes, Nol9 provides a nuclear polynucleotide 5'-kinase required for ribosomal RNA processing, while a HeLa nuclear 5'-hydroxyl polyribonucleotide kinase highlights RNA-specific 5'-phosphorylation. The activity is also a practical target for electrochemical biosensors and rolling circle amplification assays. Together, these findings make GO:0051731 a compact but important node linking nucleic acid end chemistry to RNA biology and assay development.
References
- 1. Luo D et al.. 2024. An electrochemical biosensor for detection of T4 polynucleotide kinase activity based on host-guest recognition between phosphate pillararene and methylene blue.. Talanta 266(Pt 1):124956 PMID: 37499362
- 2. Su A et al.. 2024. An electrochemical biosensor for T4 polynucleotide kinase activity assay based on host-guest recognition between phosphate pillararene@MWCNTs and thionine.. Analyst 149(4):1271-1279 PMID: 38226548
- 3. Wu Y et al.. 2023. An electrochemical biosensor for T4 polynucleotide kinase activity identification according to host-guest recognition among phosphate pillararene@palladium nanoparticles@reduced graphene oxide nanocomposite and toluidine blue.. Mikrochim Acta 190(10):394 PMID: 37715009
- 4. Cameron V et al.. 1977. 3'-Phosphatase activity in T4 polynucleotide kinase.. Biochemistry 16(23):5120-6 PMID: 199248
- 5. Pick L et al.. 1986. Purification of wheat germ RNA ligase. I. Characterization of a ligase-associated 5'-hydroxyl polynucleotide kinase activity.. J Biol Chem 261(15):6684-93 PMID: 3009470
- 6. Heindl K et al.. 2010. Nol9 is a novel polynucleotide 5'-kinase involved in ribosomal RNA processing.. EMBO J 29(24):4161-71 PMID: 21063389
- 7. Tao J et al.. 2022. Electrochemical detection of T4 polynucleotide kinase activity based on magnetic Fe(3)O(4)@TiO(2) nanoparticles triggered by a rolling circle amplification strategy.. Talanta 241:123272 PMID: 35121542
- 8. Shuman S et al.. 1979. 5'-Hydroxyl polyribonucleotide kinase from HeLa cell nuclei. Purification and properties.. J Biol Chem 254(20):10396-404 PMID: 226541
