GO:0061711 tRNA N(6)-L-threonylcarbamoyladenine synthase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0061711 describes the molecular function that attaches a threonylcarbamoyl group to adenine 37 of tRNA, forming the universal modification t6A.
• The reaction consumes L-threonylcarbamoyladenylate and produces AMP plus N(6)-L-threonylcarbamoyladenine(37) in tRNA.
• t6A is found at position 37 of tRNAs that read ANN codons and is required for efficient and accurate translation.
• The synthase belongs to the TsaC/Sua5 family and uses a conserved ATP-pyrophosphate exchange mechanism to activate threonine and bicarbonate.
• Loss of t6A synthase activity impairs protein synthesis and has been linked to neurodevelopmental and mitochondrial phenotypes in model organisms.
• Chemoproteomic and structural methods are now used to map RNA-modification enzymes and their substrate interactions [1,2].
Description
GO:0061711, tRNA N(6)-L-threonylcarbamoyladenine synthase activity, is a molecular function that installs the threonylcarbamoyl group on adenine 37 of tRNA, generating the hypermodified nucleoside N(6)-L-threonylcarbamoyladenine (t6A). This modification is nearly universal in tRNAs that decode ANN codons and is critical for codon-anticodon interactions and translational fidelity. The enzyme catalyzes the reaction L-threonylcarbamoyladenylate + adenine(37) in tRNA = AMP + N(6)-L-threonylcarbamoyladenine(37) in tRNA, as defined by QuickGO. Researchers study this activity because t6A deficiency perturbs the proteome and has been associated with human disease phenotypes in several systems. Structural and biochemical work has revealed that the synthase uses a conserved fold and a two-step mechanism involving an activated intermediate. Chemoproteomic approaches have further expanded the toolkit for studying RNA-modification enzymes and their interactions.
tRNA N(6)-L-threonylcarbamoyladenine synthase activity At A Glance
| GO ID | GO:0061711 |
|---|---|
| GO term | tRNA N(6)-L-threonylcarbamoyladenine synthase activity |
| Ontology | molecular_function |
| Synonym | N(6)-L-threonylcarbamoyladenine synthase activity; t6A synthase activity |
| Major function | Catalyzes the transfer of a threonylcarbamoyl group to adenine 37 of tRNA to form t6A |
| Reaction | L-threonylcarbamoyladenylate + adenine(37) in tRNA = AMP + N(6)-L-threonylcarbamoyladenine(37) in tRNA |
| Substrate | L-threonylcarbamoyladenylate and adenine(37) in tRNA |
| Product | AMP and N(6)-L-threonylcarbamoyladenine(37) in tRNA |
| Related activity | t6A biosynthesis and tRNA modification |
What Is GO:0061711?
In simple terms, GO:0061711 is the enzyme activity that adds a threonylcarbamoyl chemical tag to a specific adenosine in tRNA. The official definition is: Catalysis of the reaction: L-threonylcarbamoyladenylate + adenine(37) in tRNA = AMP + N(6)-L-threonylcarbamoyladenine(37) in tRNA. The activity is also known as N(6)-L-threonylcarbamoyladenine synthase activity or t6A synthase activity. It belongs to the molecular_function ontology aspect and is responsible for producing the t6A modification at position 37 of tRNA.
Why Is tRNA N(6)-L-threonylcarbamoyladenine synthase activity Important in Cell Biology?
GO:0061711 is important because t6A is a universally conserved tRNA modification that directly influences translation efficiency and fidelity. Without this activity, tRNAs that read ANN codons cannot properly stabilize codon-anticodon pairing, leading to ribosomal pausing and proteome imbalance. Because translation is central to cell growth and stress responses, defects in t6A synthase activity can affect development, mitochondrial function, and neuronal survival. Studying this activity also provides a paradigm for understanding how RNA-modifying enzymes recognize their substrates, which is relevant to drug discovery and chemoproteomic profiling [1,2].
• t6A is required for accurate decoding of ANN codons during translation.
• Loss of t6A synthase activity causes ribosome pausing and protein aggregation in model systems.
• t6A modification is conserved from bacteria to humans, making it a tractable research target.
• Mutations in t6A pathway genes have been linked to neurodevelopmental disorders.
• The synthase is a potential target for antimicrobial and anticancer strategies.
• Chemoproteomic probes can identify RNA-modification enzymes and their interactors.
• Structural studies of the synthase reveal druggable pockets and substrate-binding residues.
• t6A levels can serve as biomarkers of translational stress.
Molecular Mechanism of tRNA N(6)-L-threonylcarbamoyladenine synthase activity
Substrate recognition and activation
In simple terms: The enzyme first grabs threonine and bicarbonate and turns them into an activated intermediate.
The synthase uses ATP to activate L-threonine and bicarbonate, forming L-threonylcarbamoyladenylate, a high-energy intermediate. Structural analysis by NMR shows that the enzyme binds threonine and ATP in a conserved pocket and undergoes conformational changes upon substrate binding. This step is essential for transferring the threonylcarbamoyl group to tRNA.
Transfer to adenine 37 of tRNA
In simple terms: The activated group is then attached to a specific adenine in the tRNA loop.
The enzyme transfers the threonylcarbamoyl moiety from L-threonylcarbamoyladenylate to the N6 position of adenine 37 in tRNA, releasing AMP. This reaction occurs on tRNAs that read ANN codons and requires proper folding of the anticodon loop. The modification stabilizes the U-turn structure of the anticodon loop and enhances codon-anticodon interactions.
Catalytic residues and cofactors
In simple terms: Specific amino acids in the enzyme do the chemistry, and no metal cofactor is strictly required.
Mutational and structural studies have identified conserved residues in the TsaC/Sua5 family that coordinate substrates and stabilize the transition state. Unlike some radical SAM enzymes, t6A synthase does not require iron-sulfur clusters for its core activity. The reaction is driven by ATP hydrolysis and the intrinsic reactivity of the activated intermediate.
Regulation and quality control
In simple terms: The cell adjusts t6A levels according to growth conditions and stress.
t6A synthase activity can be regulated at the level of gene expression and by substrate availability. In bacteria, the synthase is part of an operon with other tRNA-modification genes, allowing coordinated regulation. Quality-control pathways monitor tRNA integrity and can degrade hypomodified tRNAs under stress.
Key Genes Involved in GO:0061711 tRNA N(6)-L-threonylcarbamoyladenine synthase activity
The following genes and proteins are experimentally linked to t6A biosynthesis and the broader tRNA-modification network.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TsaC/Sua5 | t6A synthase that forms L-threonylcarbamoyladenylate | Core enzyme for GO:0061711; structural and mechanistic studies |
| TsaD | Component of the t6A synthesis complex in bacteria | Essential for t6A formation and translation |
| TsaB | Accessory protein in the t6A synthesis complex | Required for efficient t6A modification |
| TsaE | ATPase that regulates the t6A complex | Controls the activity of the synthase complex |
| YgjD | Homolog of TsaD in Gram-positive bacteria | Model for t6A pathway conservation |
| YeaZ | Homolog of TsaB | Supports t6A synthesis in bacteria |
| YjeE | Homolog of TsaE | Regulates t6A complex assembly |
| Sua5 | Eukaryotic t6A synthase | Links t6A to translation in eukaryotes |
| Kae1 | Eukaryotic homolog of TsaD | Part of the EKC complex for t6A synthesis |
| Bud32 | Kinase in the EKC complex | Regulates t6A synthesis and stress responses |
| Cgi121 | Component of the EKC complex | Modulates t6A synthase activity |
| Gon7 | EKC complex subunit | Required for efficient t6A modification |
| Pcc1 | EKC complex subunit | Stabilizes the t6A synthesis machinery |
| MiaB | Radical SAM enzyme for tRNA thiolation/methylation | Related tRNA modification enzyme for comparative studies [5,8] |
| RimO | Radical SAM methylthiotransferase | Model for tRNA modification enzymology |
| MiaA | tRNA modification enzyme | Comparative target for RNA-modifying enzymes |
| TrmA | tRNA methyltransferase | Used as a control in modification studies |
How Is tRNA N(6)-L-threonylcarbamoyladenine synthase activity Regulated?
t6A synthase activity is regulated by substrate availability, complex assembly, and stress-responsive signaling. In bacteria, the tsaC gene is co-transcribed with other tRNA-modification genes, allowing coordinated expression. In eukaryotes, the EKC complex subunits can be phosphorylated, which may alter t6A synthesis under stress. Chemoproteomic profiling has revealed that RNA-modification enzymes are dynamically regulated and can be targeted by small molecules.
tRNA N(6)-L-threonylcarbamoyladenine synthase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| Sua5 | Neurodevelopmental delay | Knockout zebrafish or mouse models |
| Kae1 | Mitochondrial dysfunction | Patient-derived fibroblasts with point mutations |
| TsaC | Bacterial translation defects | Bacterial knockout strains |
| TsaD | Cell cycle and growth defects | Conditional knockout cell lines |
| Bud32 | Stress response and cancer | Overexpression and knockdown models |
Neurodevelopmental disorders
Defects in t6A synthesis have been associated with neurodevelopmental phenotypes in model organisms, likely due to impaired translation of key neuronal transcripts. Mutations in EKC complex genes can cause developmental delay and microcephaly in humans. Studying GO:0061711 helps clarify how tRNA modification defects contribute to these disorders.
Mitochondrial dysfunction
t6A modification is required for efficient mitochondrial translation, and loss of synthase activity can impair oxidative phosphorylation. This links GO:0061711 to mitochondrial disease phenotypes. Experimental models with reduced t6A levels show respiratory chain defects.
Cancer and translational stress
Cancer cells often have elevated translation rates and may depend on tRNA modifications for survival. Inhibiting t6A synthase activity could selectively sensitize tumors to translational stress. Chemoproteomic tools can help identify inhibitors of RNA-modification enzymes.
From tRNA N(6)-L-threonylcarbamoyladenine synthase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of t6A synthase impair translation? | CRISPR knockout of Sua5 in human cells |
| Which residues are essential for catalysis? | Point mutations in TsaC/Sua5 |
| Can t6A levels be restored by knock-in? | Knock-in of wild-type or mutant synthase |
| Where is the synthase localized? | Tagged knock-in with fluorescent protein |
| Does overexpression affect growth? | Overexpression of TsaC in bacteria |
| What proteins interact with the synthase? | Affinity purification with tagged knock-in |
How to Study the tRNA N(6)-L-threonylcarbamoyladenine synthase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NMR spectroscopy | Substrate binding and conformational changes | Structural studies of TsaC/Sua5 |
| X-ray crystallography | Three-dimensional structure of the synthase | Active-site mapping |
| Ribo-seq | Ribosome occupancy and pausing | Translation fidelity assays |
| Mass spectrometry | t6A levels in tRNA | Quantification of modification |
| Chemoproteomics | Enzyme-small molecule interactions | Drug target profiling |
| CRISPR knockout | Gene function loss | Phenotypic analysis |
| Western blot | Protein expression levels | Validation of knockout/overexpression |
Structural analysis by NMR and crystallography
NMR-based structural analysis has been used to determine how the synthase binds substrates and undergoes conformational changes. Crystallography can reveal the active-site architecture and guide inhibitor design.
Chemoproteomic profiling
Chemoproteomic approaches enable the study of RNA-modification enzymes and their interactions with small molecules. These methods can identify off-target effects and guide drug development.
Ribo-seq and translation profiling
Ribo-seq measures ribosome occupancy and can detect pausing caused by loss of t6A. This method is useful for linking GO:0061711 to translational fidelity.
RNA modification mapping
Mass spectrometry and sequencing-based methods can quantify t6A levels in tRNA. These approaches are essential for validating synthase activity in cells.
How CRISPR Can Be Used to Study GO:0061711 tRNA N(6)-L-threonylcarbamoyladenine synthase activity
Knockout
CRISPR knockout of t6A synthase genes such as Sua5 or TsaC can abolish t6A modification and reveal growth and translation defects. These models are useful for studying the essentiality of GO:0061711 in different cell types.
Point Mutation
Point mutations in catalytic residues of the synthase can separate substrate binding from catalysis. Such models help define the precise chemistry of GO:0061711.
Knock-in
Knock-in of tagged or mutant synthase allows localization and interaction studies. This approach can also restore t6A levels in knockout backgrounds.
Overexpression
Overexpression of the synthase can increase t6A levels and may affect translation and stress responses. It is useful for gain-of-function studies.
How EDITGENE Supports tRNA N(6)-L-threonylcarbamoyladenine synthase activity Research
Researchers studying tRNA N(6)-L-threonylcarbamoyladenine synthase activity-related genes often need to determine whether a candidate gene is causally involved in translation, stress responses, or disease phenotypes. EDITGENE provides validated CRISPR models and bioinformatics support to accelerate this work.
Contact EDITGENE today to design your custom CRISPR model for tRNA N(6)-L-threonylcarbamoyladenine synthase activity research.
Frequently Asked Questions About tRNA N(6)-L-threonylcarbamoyladenine synthase activity
What is tRNA N(6)-L-threonylcarbamoyladenine synthase activity?
It is the enzyme activity defined by GO:0061711 that adds a threonylcarbamoyl group to adenine 37 of tRNA, forming t6A.
What genes are involved in tRNA N(6)-L-threonylcarbamoyladenine synthase activity?
Key genes include TsaC/Sua5, TsaD, TsaB, TsaE, and eukaryotic EKC complex subunits such as Kae1 and Bud32.
What is the reaction catalyzed by GO:0061711?
The reaction is L-threonylcarbamoyladenylate + adenine(37) in tRNA = AMP + N(6)-L-threonylcarbamoyladenine(37) in tRNA.
Why is t6A modification important?
t6A stabilizes codon-anticodon interactions and is required for efficient and accurate translation.
What diseases are linked to t6A synthase defects?
Defects have been associated with neurodevelopmental disorders and mitochondrial dysfunction.
How can I study GO:0061711 in the lab?
Common methods include CRISPR knockout, point mutations, Ribo-seq, mass spectrometry, and structural analysis [1,2].
What is the difference between t6A synthase and other tRNA-modifying enzymes?
t6A synthase specifically forms t6A, whereas other enzymes such as MiaB and RimO catalyze different tRNA modifications [5,6,8].
Can t6A levels be measured?
Yes, mass spectrometry and sequencing-based methods can quantify t6A in tRNA.
Is t6A synthase conserved in humans?
Yes, the Sua5/Kae1 pathway is conserved from bacteria to humans.
What CRISPR models are available for t6A research?
EDITGENE offers knockout, point-mutation, knock-in, and overexpression models for t6A pathway genes.
Conclusion
GO:0061711, tRNA N(6)-L-threonylcarbamoyladenine synthase activity, is a central enzyme function for tRNA modification and translation fidelity. Its study bridges structural biology, chemoproteomics, and disease modeling [1,2]. EDITGENE provides comprehensive CRISPR solutions to interrogate this activity in relevant cell models.
References
- 1. Dai W et al.. 2023. Chemoproteomic Approaches to Studying RNA Modification-Associated Proteins.. Acc Chem Res 56(19):2726-2739 PMID: 37733063
- 2. Harris KA et al.. 2015. NMR-based Structural Analysis of Threonylcarbamoyl-AMP Synthase and Its Substrate Interactions.. J Biol Chem 290(33):20032-43 PMID: 26060251
- 5. Pierrel F et al.. 2003. MiaB protein from Thermotoga maritima. Characterization of an extremely thermophilic tRNA-methylthiotransferase.. J Biol Chem 278(32):29515-24 PMID: 12766153
- 6. Lee KH et al.. 2009. Characterization of RimO, a new member of the methylthiotransferase subclass of the radical SAM superfamily.. Biochemistry 48(42):10162-74 PMID: 19736993
- 8. Hernández HL et al.. 2007. MiaB, a bifunctional radical-S-adenosylmethionine enzyme involved in the thiolation and methylation of tRNA, contains two essential [4Fe-4S] clusters.. Biochemistry 46(17):5140-7 PMID: 17407324
