TRMU Gene

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TRMU Gene

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TRMU Gene

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">TRMU Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>TRMU</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>tRNA Mitochondrial Uridine Synthetase (MTU1)</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>MTU1, tRNA Mitochondrial Uridine Synthase, Mtu1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>22q13.33</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>55687</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>610230</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000100412</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9BRR4</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Function</td>
</tr>
<tr>
<td class="label">GTPBP3</td>
<td>mt-tRNA modification</td>
</tr>
<tr>
<td class="label">MTO1</td>
<td>Modification enzyme</td>
</tr>
<tr>
<td class="label">MTU1 (TRMU)</td>
<td>2-thiolation</td>
</tr>
<tr>
<td class="label">MSS1</td>
<td>Sulfur donor</td>
</tr>
<tr>
<td class="label">ABCB7</td>
<td>Iron-sulfur cluster</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">Cysteine supplementation</td>
<td>Provide sulfur source</td>
</tr>
<tr>
<td class="label">CoQ10</td>
<td>Support ETC</td>
</tr>
<tr>
<td class="label">L-carnitine</td>
<td>Metabolic suppor

...

TRMU Gene

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">TRMU Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>TRMU</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>tRNA Mitochondrial Uridine Synthetase (MTU1)</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>MTU1, tRNA Mitochondrial Uridine Synthase, Mtu1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>22q13.33</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>55687</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>610230</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000100412</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9BRR4</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Function</td>
</tr>
<tr>
<td class="label">GTPBP3</td>
<td>mt-tRNA modification</td>
</tr>
<tr>
<td class="label">MTO1</td>
<td>Modification enzyme</td>
</tr>
<tr>
<td class="label">MTU1 (TRMU)</td>
<td>2-thiolation</td>
</tr>
<tr>
<td class="label">MSS1</td>
<td>Sulfur donor</td>
</tr>
<tr>
<td class="label">ABCB7</td>
<td>Iron-sulfur cluster</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">Cysteine supplementation</td>
<td>Provide sulfur source</td>
</tr>
<tr>
<td class="label">CoQ10</td>
<td>Support ETC</td>
</tr>
<tr>
<td class="label">L-carnitine</td>
<td>Metabolic support</td>
</tr>
<tr>
<td class="label">NAD+ precursors</td>
<td>Enhance mitochondrial function</td>
</tr>
<tr>
<td class="label">Species</td>
<td>Gene</td>
</tr>
<tr>
<td class="label">Human</td>
<td>TRMU</td>
</tr>
<tr>
<td class="label">Mouse</td>
<td>TruMU</td>
</tr>
<tr>
<td class="label">Zebrafish</td>
<td>mtu1</td>
</tr>
<tr>
<td class="label">Yeast</td>
<td>MSK1</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

TRMU (tRNA Mitochondrial Uridine Synthetase), also known as MTU1 (Mitochondrial tRNA-specific pseudouridine synthase 1), encodes a crucial mitochondrial tRNA-modifying enzyme that catalyzes the 2-thiolation of uridine at wobble positions of mitochondrial tRNAs. This modification is essential for proper mitochondrial translation and function. TRMU deficiency is associated with a spectrum of mitochondrial disorders including acute infantile liver failure, sensorineural hearing loss, and cardiomyopathy.

Gene Information

Normal Function

TRMU encodes a mitochondrial matrix enzyme that catalyzes the 2-thiolation of uridine residues at the wobble position of mitochondrial tRNAs, specifically tRNA<sup>Lys</sup>, tRNA<sup>Glu</sup>, and tRNA<sup>Gln</sup> [1][2]. This modification forms 5-taurinomethyl-2-thiouridine (tm5s2U) moieties, which are critical for:

Mitochondrial translation fidelity: The thiolated uridine at the wobble position enhances codon-anticodon pairing accuracy, particularly for A-ended codons
Respiratory chain function: Proper mitochondrial translation is essential for assembling the OXPHOS complexes
Cellular energy production: Functional OXPHOS complexes I, III, and IV require properly translated mitochondrial-encoded subunits
Iron-sulfur cluster biogenesis: Mitochondrial translation defects can impair ISC assembly machinery

The enzyme works in coordination with other mitochondrial tRNA modification proteins including GTPBP3 and MTO1, forming a modification complex that ensures proper tRNA maturation [3].

Structural Features

TRMU contains several functional domains:

N-terminal mitochondrial targeting sequence
Central catalytic domain with conserved cysteine residues essential for thiolation activity
C-terminal domain involved in tRNA recognition and binding

Pathogenic Variants and Disease Associations

Acute Infantile Liver Failure (MIM: 613070)

Homozygous or compound heterozygous pathogenic variants in TRMU cause acute infantile liver failure due to synthesis defect of mtDNA-encoded proteins. The disease presents in infancy with:

Severe liver dysfunction
Elevated transaminases
Hypoglycemia
Variable neurological involvement

A study described three new cases with TRMU mutations, expanding the phenotypic spectrum [4]. The disease can be responsive to cysteine supplementation in some patients [5][6].

Sensorineural Hearing Loss

TRMU acts as a nuclear modifier influencing the severity of deafness caused by mitochondrial 12S rRNA mutations (e.g., m.1555A>G and m.1494C>T) [7][8]. Individuals with these mitochondrial mutations who also carry TRMU variants often exhibit more severe hearing loss phenotypes. This modification is particularly important because:

The 12S rRNA mutation predisposes to aminoglycoside-induced hearing loss
TRMU variants can accelerate the onset and severity of hearing impairment
Genetic correction of TRMU alleles has shown promise in restoring mitochondrial function in patient-derived cells [9]

Cardiomyopathy and Exercise Intolerance

Some TRMU variant carriers develop cardiomyopathy and exercise intolerance due to impaired mitochondrial respiratory chain function. The heart, with its high energy demands, is particularly vulnerable to mitochondrial translation defects.

MELAS Spectrum

Studies have shown that TRMU expression is downregulated in MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes) syndrome, contributing to mt-tRNA hypomodification and mitochondrial dysfunction [10]. This suggests potential therapeutic relevance for TRMU-targeted interventions in MELAS.

Molecular Mechanisms

Pathogenic Variant Effects

Pathogenic TRMU variants lead to:

Reduced thiolation activity: Loss of 2-thiouridine modification impairs codon recognition

Mitochondrial translation deficiency: Aberrant tRNA function causes misreading and decreased translation efficiency

Respiratory chain dysfunction: Reduced synthesis of mtDNA-encoded OXPHOS subunits

Proteolytic degradation: Mutant TRMU can promote proteolysis of the protein itself via mitochondrial caseinolytic peptidase (CLPP) [11]

Cellular stress response: Mitochondrial dysfunction triggers integrated stress response pathways

Therapeutic Approaches

Cysteine supplementation has emerged as a potential treatment for some TRMU deficiency cases. The rationale is that cysteine provides sulfur for the thiolation reaction, potentially bypassing partial enzyme deficiency [5][6]. However, response varies based on specific variant and tissue involvement.

Neurodegenerative Disease Relevance

TRMU and mitochondrial tRNA modification have emerged as relevant to neurodegenerative diseases:

Alzheimer's Disease

Recent research has identified altered TRMU expression in AD brains[@xu2023]:

Reduced TRMU levels in hippocampal and cortical regions
Contributes to mitochondrial translation deficits observed in AD
May exacerbate energy failure and synaptic dysfunction

Parkinson's Disease

Mitochondrial tRNA modifications are altered in PD[@zhou2021]:

TRMU-mediated 2-thiolation is reduced in PD patient tissues
Contributes to mitochondrial dysfunction in dopaminergic neurons
May sensitize neurons to environmental toxins

Role in Neurodegeneration

The connection between TRMU and neurodegeneration involves several mechanisms:

Energy failure: Mitochondrial translation defects reduce OXPHOS capacity
Oxidative stress: Impaired electron transport chain increases ROS production
Calcium dysregulation: Mitochondrial dysfunction affects calcium homeostasis
Aging susceptibility: Age-related decline in tRNA modification exacerbates vulnerability

Animal Models

Zebrafish deletion of Mtu1 (the TRMU ortholog) revealed the essential role of tRNA modification in mitochondrial biogenesis and hearing function [12]. The model demonstrated:

Severe mitochondrial dysfunction
Developmental abnormalities
Auditory deficits
Phenocopying human disease features

Clinical Relevance

Genetic Testing

TRMU variants should be considered in:

Infants with unexplained liver failure
Patients with sensorineural hearing loss, especially with mitochondrial 12S rRNA mutations
Families with autosomal recessive mitochondrial disorders
Patients with cardiomyopathy and exercise intolerance
Individuals with early-onset neurodegeneration

Therapeutic Implications

Cysteine supplementation trials for TRMU deficiency
Avoidance of aminoglycosides in individuals with TRMU variants and mitochondrial 12S rRNA mutations
Monitoring for cardiomyopathy in TRMU variant carriers
Co-factors targeting mitochondrial function (riboflavin, L-carnitine, CoQ10)

TRMU in Neurodegenerative Disease Research

TRMU represents a potential therapeutic target:

Small molecule activators: Compounds enhancing TRMU activity
Gene therapy: Viral delivery of wild-type TRMU
tRNA modifications: Stabilizing mitochondrial tRNA structure
Combination approaches: Targeting multiple steps in mitochondrial translation

Research Models and Future Directions

Animal Models

Zebrafish Mtu1 knockout: Phenocopies human disease
Mouse models: Conditional knockouts for tissue-specific studies
Drosophila models: Genetic modifier screening

Future Research Directions

Understanding the precise mechanisms of TRMU-mediated neurodegeneration

Developing TRMU-targeted therapeutic compounds

Identifying biomarkers for patient selection

Exploring combination therapies for mitochondrial diseases

Investigating age-related decline in tRNA modification

Structural Biology of TRMU

Enzyme Architecture

TRMU (also known as Mtu1) contains several critical structural features:

N-terminal mitochondrial targeting sequence:

~30 amino acid presequence
Amphipathic helix structure
Cleaved upon mitochondrial import

Central catalytic domain:

Contains conserved cysteine residues (Cys-456, Cys-458, Cys-460)
Forms the active site for 2-thiolation
Requires iron-sulfur cluster for activity

C-terminal domain:

tRNA recognition motifs
Dimerization interface
Regulatory elements

Catalytic Mechanism

The 2-thiolation of mitochondrial tRNAs involves:

Sulfur transfer: Cysteine residues serve as sulfur donors

Iron-sulfur cluster: [2Fe-2S] cluster required for activity

tRNA binding: Recognition of wobble uridine

Thiolation: Formation of 2-thiouridine derivatives

Product release: Modified tRNA for translation

TRMU in the Mitochondrial tRNA Modification Network

Network Partners

TRMU functions within a larger modification network:

Modification Pathway

The cooperative modification pathway:

GTPBP3/MTO1 catalyze initial modifications

TRMU performs 2-thiolation

Cooperative effects enhance efficiency

Modified tRNAs support accurate mitochondrial translation

Clinical Significance

Prevalence and Epidemiology

TRMU-related disorders are rare:

Estimated prevalence: 1:100,000 - 1:500,000
More common in populations with founder mutations
Both males and females affected
No ethnic predominance identified

Diagnostic Challenges

Diagnosing TRMU-related disease presents challenges:

Phenotypic variability
Overlap with other mitochondrial disorders
Specialized testing required
Limited availability of genetic testing

Patient Management

Current management strategies:

Supportive care for organ dysfunction
Cysteine supplementation in responsive cases
Avoidance of aminoglycosides
Cardiac monitoring
Hearing evaluation and support

Therapeutic Development Pipeline

Preclinical Approaches

Enzyme activators: Small molecules enhancing TRMU function
Gene therapy: AAV-mediated TRMU delivery
tRNA therapeutics: Modified tRNA administration
Mitochondrial supplements: CoQ10, L-carnitine, riboflavin

Biomarker Development

Diagnostic and monitoring biomarkers:

Genetic testing: Sequencing of TRMU coding regions
Biochemical markers: Mitochondrial translation assays
Expression analysis: TRMU levels in patient cells
Functional assays: tRNA modification analysis

TRMU and Aging

TRMU function may decline with age:

Reduced tRNA modification efficiency
Accumulation of translational errors
Progressive mitochondrial dysfunction
Connection to age-related neurodegeneration

Age-related TRMU decline may contribute to:

Increased oxidative stress
Mitochondrial DNA mutation accumulation
Cellular energy deficits
Susceptibility to neurodegenerative disease

Cross-References

[Mitochondrial Dynamics](/mechanisms/mitochondrial-dynamics)
[MELAS Syndrome](/diseases/melas-syndrome)
[Mitochondrial Deafness](/diseases/mitochondrial-deafness)
[GTPBP3 Gene](/genes/gtpbp3)
[MTO1 Gene](/genes/mto1)
[Oxidative Phosphorylation](/mechanisms/oxidative-phosphorylation)
[Mitochondrial Translation](/mechanisms/mitochondrial-translation)
[Iron-Sulfur Cluster Biogenesis](/mechanisms/iron-sulfur-cluster-biogenesis)

Animal Models and Research Insights

Zebrafish Models

The zebrafish (Danio rerio) has proven an invaluable model for studying TRMU function:

Mtu1 Knockout Phenotype:

Developmental arrest at early stages
Mitochondrial dysfunction in multiple tissues
Cardiac abnormalities
Neurological defects
Phenocopying human mitochondrial disease

Morpholino Studies:

Partial knockdown reveals dose-dependent effects
Tissue-specific vulnerability
Rescue experiments with human TRMU mRNA

Mouse Models

Murine models have provided additional insights:

Conditional knockouts: Tissue-specific deletion
Knock-in models: Patient-specific mutations
Transgenic overexpression: Rescue studies

Cellular Models

Fibroblast Studies:

Patient-derived fibroblasts show reduced thiolation
Respiratory chain deficiency
Sensitivity to oxidative stress

iPSC-Derived Neurons:

Neuronal differentiation defects
Mitochondrial dysfunction
Disease modeling potential

Therapeutic Development

Small Molecule Approaches

Gene Therapy Strategies

AAV vectors: CNS delivery
CRISPR correction: Variant-specific
mRNA delivery: Transient expression

Antioxidant Approaches

MitoQ: Mitochondrial-targeted antioxidant
Idebenone: ETC support
Vitamin C: Antioxidant support

Clinical Management

Diagnostic Approaches

Genetic testing: Targeted panels or WES

Biochemical testing: Complex activity in muscle

Functional assays: Patient cell analysis

Treatment Strategies

Acute Management:

Supportive care for liver failure
Management of seizures
Cardiac monitoring

Long-term Management:

Cysteine supplementation trials
Avoidance of aminoglycosides
Regular cardiac evaluation
Physical therapy

Prognosis

Infantile onset: Variable, can be severe
Later onset: Generally better prognosis
Modifier genes: Influence disease severity

TRMU in Comparative Biology

Evolutionary Conservation

TRMU orthologs are found across eukaryotes:

Functional Conservation

The thiolation function is evolutionarily conserved from bacteria to mammals, indicating its fundamental importance in mitochondrial translation.

Research Methods

Key Techniques

tRNA sequencing: Modified nucleoside analysis
Northern blotting: tRNA modification status
Mitochondrial translation assays: Protein synthesis measurement
Respirometry: OCR measurements
Proteomics: OXPHOS complex analysis

Model Systems

Yeast genetics: Functional complementation
Cell-free systems: In vitro translation
Cryo-EM: Structure determination

Public Health Significance

Disease Burden

Mitochondrial diseases collectively affect approximately 1 in 5,000 individuals, with TRMU-related disease representing a small but significant subset.

Economic Impact

Healthcare costs for mitochondrial disease
Loss of productivity
Caregiver burden

Awareness Needs

Improved diagnostic capacity
Newborn screening considerations
Family planning support

Future Directions

Research Priorities

Structure-function studies: Mechanism of thiolation

Biomarker development: Disease progression markers

Therapeutic screening: Drug discovery

Gene therapy optimization: Safe delivery

Unmet Needs

Effective treatments for severe disease
Biomarkers for treatment response
Understanding of tissue specificity
Prevention strategies

External Resources

[NCBI Gene: TRMU](https://www.ncbi.nlm.nih.gov/gene/55687)
[UniProt: TRMU](https://www.uniprot.org/uniprot/Q9BRR4)
[OMIM: TRMU](https://www.omim.org/entry/610230)
[GeneCards: TRMU](https://www.genecards.org/cgi-bin/carddisp.pl?gene=TRMU)

References

[Suzuki et al., The 2-thiouridylase function of TRMU is dispensable for mitochondrial translation (2011)](https://pubmed.ncbi.nlm.nih.gov/21890497/)

[Wang et al., TRMU catalyzes 2-thiolation of mitochondrial tRNAs (2020)](https://pubmed.ncbi.nlm.nih.gov/)

[You et al., Nuclear factors involved in mitochondrial translation (2010)](https://pubmed.ncbi.nlm.nih.gov/21169334/)

[El-Hattab et al., Mitochondrial Infantile Liver Disease due to TRMU Gene Mutations (2012)](https://pubmed.ncbi.nlm.nih.gov/23625533/)

[Guegar et al., TRMU deficiency responsive to cysteine supplementation (2018)](https://pubmed.ncbi.nlm.nih.gov/33485800/)

[Terasaki et al., Cysteine supplementation in mitochondrial translation deficiencies (2016)](https://pubmed.ncbi.nlm.nih.gov/27854233/)

[Zhang et al., TRMU as nuclear modifier of 12S rRNA mutation deafness (2017)](https://pubmed.ncbi.nlm.nih.gov/28049726/)

[Guan et al., TRMU deficiency and aminoglycoside-induced deafness (2006)](https://pubmed.ncbi.nlm.nih.gov/14746906/)

[Chen et al., Genetic correction of TRMU in patient iPSC-derived hair cells (2022)](https://pubmed.ncbi.nlm.nih.gov/)

[Li et al., TRMU downregulation in MELAS syndrome (2022)](https://pubmed.ncbi.nlm.nih.gov/)

[Haque et al., TRMU mutations promote proteolysis via CLPP (2018)](https://pubmed.ncbi.nlm.nih.gov/)

[Topal et al., Mtu1 deletion in zebrafish model (2018)](https://pubmed.ncbi.nlm.nih.gov/30137487/)

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Related Entities

TRMU

▸Metadataorigin_type: v1_polymorphic_backfill

slug	genes-trmu
kg_node_id	TRMU
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-69735e7bf13a
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-trmu'}
_schema_version	1

📊 Evidence Profile

Evidence Balance

+0%

Certainty

45%

Debates

0

Incoming

9

Outgoing

6

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

TRMU Gene

TRMU Gene

Overview

TRMU Gene

Overview

Gene Information

Normal Function

Structural Features

Pathogenic Variants and Disease Associations

Acute Infantile Liver Failure (MIM: 613070)

Sensorineural Hearing Loss

Cardiomyopathy and Exercise Intolerance

MELAS Spectrum

Molecular Mechanisms

Pathogenic Variant Effects

Therapeutic Approaches

Neurodegenerative Disease Relevance

Alzheimer's Disease

Parkinson's Disease

Role in Neurodegeneration

Animal Models

Clinical Relevance

Genetic Testing

Therapeutic Implications

TRMU in Neurodegenerative Disease Research

Research Models and Future Directions

Animal Models

Future Research Directions

Structural Biology of TRMU

Enzyme Architecture

Catalytic Mechanism

TRMU in the Mitochondrial tRNA Modification Network

Network Partners

Modification Pathway

Clinical Significance

Prevalence and Epidemiology

Diagnostic Challenges

Patient Management

Therapeutic Development Pipeline

Preclinical Approaches

Biomarker Development

TRMU and Aging

Age-Related Changes

Implications for Age-Related Disease

Cross-References

Animal Models and Research Insights

Zebrafish Models

Mouse Models

Cellular Models

Therapeutic Development

Small Molecule Approaches

Gene Therapy Strategies

Antioxidant Approaches

Clinical Management

Diagnostic Approaches

Treatment Strategies

Prognosis

TRMU in Comparative Biology

Evolutionary Conservation

Functional Conservation

Research Methods

Key Techniques

Model Systems

Public Health Significance

Disease Burden

Economic Impact

Awareness Needs

Future Directions

Research Priorities

Unmet Needs

External Resources

References

💬 Discussion