CARS2

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CARS2

<div class="infobox infobox-gene">
<div class="infobox-header">CARS2</div>
<div class="infobox-content">
<div class="infobox-row"><strong>Full Name:</strong> Mitochondrial Cysteinyl-tRNA Synthetase</div>
<div class="infobox-row"><strong>Symbol:</strong> CARS2</div>
<div class="infobox-row"><strong>Chromosomal Location:</strong> 13q14.11</div>
<div class="infobox-row"><strong>NCBI Gene ID:</strong> 125875</div>
<div class="infobox-row"><strong>Ensembl ID:</strong> ENSG00000156206</div>
<div class="infobox-row"><strong>UniProt ID:</strong> Q9Y2R9</div>
<div class="infobox-row"><strong>Protein Length:</strong> 708 amino acids</div>
<div class="infobox-row"><strong>Molecular Weight:</strong> ~80 kDa</div>
<div class="infobox-row"><strong>Associated Diseases:</strong> Combined Oxidative Phosphorylation Deficiency, Mitochondrial Encephalomyopathy, Leigh Syndrome, Perrault Syndrome</div>
</div>
</div>

Overview

...

CARS2

<div class="infobox infobox-gene">
<div class="infobox-header">CARS2</div>
<div class="infobox-content">
<div class="infobox-row"><strong>Full Name:</strong> Mitochondrial Cysteinyl-tRNA Synthetase</div>
<div class="infobox-row"><strong>Symbol:</strong> CARS2</div>
<div class="infobox-row"><strong>Chromosomal Location:</strong> 13q14.11</div>
<div class="infobox-row"><strong>NCBI Gene ID:</strong> 125875</div>
<div class="infobox-row"><strong>Ensembl ID:</strong> ENSG00000156206</div>
<div class="infobox-row"><strong>UniProt ID:</strong> Q9Y2R9</div>
<div class="infobox-row"><strong>Protein Length:</strong> 708 amino acids</div>
<div class="infobox-row"><strong>Molecular Weight:</strong> ~80 kDa</div>
<div class="infobox-row"><strong>Associated Diseases:</strong> Combined Oxidative Phosphorylation Deficiency, Mitochondrial Encephalomyopathy, Leigh Syndrome, Perrault Syndrome</div>
</div>
</div>

Overview

CARS2 (Mitochondrial Cysteinyl-tRNA Synthetase) is a nuclear-encoded gene that encodes a mitochondrial aminoacyl-tRNA synthetase (mtARS) essential for mitochondrial protein synthesis. Aminoacyl-tRNA synthetases (ARS) are essential enzymes that catalyze the attachment of specific amino acids to their corresponding transfer RNA (tRNA) molecules, forming aminoacyl-tRNA intermediates that are then used in ribosomal protein synthesis. CARS2 specifically charges cysteine to mitochondrial tRNA^Cys, enabling the translation of mitochondrial DNA-encoded proteins within the mitochondrial matrix. Mitochondria encode 13 essential components of the oxidative phosphorylation (OXPHOS) machinery, and proper mitochondrial translation is critical for cellular energy production. Mutations in CARS2 cause mitochondrial translation defects leading to combined oxidative phosphorylation deficiencies, characterized by variable involvement of multiple mitochondrial respiratory chain complexes. The resulting energy deficit particularly affects high-energy-demand tissues including brain, skeletal muscle, and heart, manifesting as mitochondrial encephalomyopathies, Leigh syndrome, leukoencephalopathy, and sensorineural hearing loss [1][2].

Function

Aminoacyl-tRNA Synthetase Activity

CARS2 belongs to the class II aminoacyl-tRNA synthetase family and exhibits the following catalytic properties:

tRNA Recognition: CARS2 specifically recognizes mitochondrial tRNA^Cys, which contains the characteristic anticodon sequence 5'-GCA-3' (read as cysteine codon). The enzyme distinguishes mitochondrial tRNA from cytoplasmic tRNA^Cys through unique structural features including the absence of base pairs in the D-arm and a longer variable loop [3].

Aminoacylation Reaction: The catalytic cycle proceeds through two-step aminoacylation:

Activation: CARS2 first forms an aminoacyl-adenylate (aa-AMP) intermediate using ATP
Transfer: The activated amino acid is transferred to the 3'-terminal adenosine of tRNA^Cys, forming aminoacyl-tRNA

Proofreading: Some mtARS enzymes possess editing capabilities to ensure fidelity. CARS2 may include editing functions to prevent mischarging of cysteine to non-cognate tRNAs.

Mermaid diagram (expand to render)

Mitochondrial Translation

The CARS2 enzyme is essential for mitochondrial translation for several reasons:

Cysteine Codons in Mitochondrial Genomes: The mitochondrial genetic code uses the codon AGA and AGG as stop codons (not arginine as in the nuclear code), and uses AUA for methionine (not isoleucine). However, cysteine is encoded by UGU and UGC codons, which require tRNA^Cys for translation.

Limited tRNA Complement: Mitochondria possess a minimal set of tRNAs (typically 22 tRNAs) that must decode all codons through "two-out-of-three" and "UAN" codon recognition. tRNA^Cys is essential for decoding cysteine codons in all mitochondrial genes.

Complex I Assembly: Multiple cysteine-containing subunits are part of NADH:ubiquinone oxidoreductase (Complex I), making CARS2 essential for Complex I biogenesis.

Structure-Function Relationships

The CARS2 protein contains several functional domains:

N-terminal mitochondrial targeting sequence (MTS): 30-50 amino acid transit peptide that directs import into mitochondria
Catalytic domain: Core aminoacylation domain characteristic of class II synthetases
C-terminal domain: May contribute to tRNA binding and dimerization

Expression

Tissue Distribution

CARS2 exhibits highest expression in tissues with high mitochondrial demand:

| Tissue | Expression Level |
|--------|-----------------|
| Brain (cerebral cortex) | Very High |
| Brain (cerebellum) | Very High |
| Brain (substantia nigra) | High |
| Heart (cardiac muscle) | Very High |
| Skeletal muscle | Very High |
| Liver | Moderate-High |
| Kidney | Moderate |
| Pancreas | Moderate |
| Lung | Low-Moderate |

Cellular Localization

CARS2 localizes exclusively to the mitochondrial matrix, where it:

Associates with mitochondrial inner membrane
May be partially associated with mitochondrial nucleoids (mitochondrial DNA-protein complexes)
Forms homodimers for optimal function

Disease Associations

Combined Oxidative Phosphorylation Deficiency

CARS2 mutations cause variable phenotypes affecting multiple OXPHOS complexes:

Complex I Deficiency: Most common defect due to multiple Complex I subunits requiring cysteine residues. Manifests as:

Encephalopathy
Cardiomyopathy
Developmental regression

Complex IV Deficiency: Cytochrome c oxidase deficiency is also common. Features include:

Muscle hypotonia
Elevated lactate
Sensorineural hearing loss

Multiple Complex Deficiencies: Severe cases show combined deficiency of Complexes I, III, IV, and V.

Leigh Syndrome

Leigh syndrome (subacute necrotizing encephalomyelopathy) is characterized by:

Bilateral symmetric lesions in basal ganglia, brainstem, and cerebellum
Progressive neurodevelopmental regression
Hypotonia, ataxia, dystonia
Elevated lactate in blood and CSF
Variable onset from infancy to adulthood

CARS2-related Leigh syndrome typically presents in early childhood with developmental delays followed by rapid neurological decline.

Leukoencephalopathy with Thalamus and Brainstem Involvement (LBSL)

CARS2 mutations cause a distinctive pattern of white matter disease:

MRI Features:

Diffuse cerebral white matter abnormalities
Signal changes in thalamus and brainstem
Sparing of U-fibers in early stages
Posterior predominance

Clinical Features:

Progressive spastic paraparesis
Ataxia
Cognitive decline
Variable optic atrophy

Perrault Syndrome

Perrault syndrome is characterized by:

Sensorineural hearing loss: Bilateral, usually severe
Ovarian dysfunction: Primary amenorrhea, premature ovarian failure

CARS2 mutations may cause this phenotype through mitochondrial dysfunction affecting inner ear hair cells and ovarian granulosa cells.

Mitochondrial Encephalomyopathy

The broader category of mitochondrial encephalomyopathy encompasses:

MELAS overlap: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes
MERRF features: Myoclonic epilepsy with ragged-red fibers
KSS-like phenotype: Kearns-Sayre syndrome variant

Pathogenic Mechanisms

OXPHOS Dysfunction

The primary disease mechanism involves impaired mitochondrial translation leading to:

Reduced synthesis of mitochondrial-encoded proteins: Critical subunits of respiratory chain complexes fail to be produced

Assembly defects: Incomplete complexes are unstable and degrade

Reduced oxidative phosphorylation: ATP production falls

Secondary respiratory chain dysfunction: Electron transport chain becomes impaired

Energy Failure

The ATP deficit particularly affects:

Neurons: High energy demand for action potentials and synaptic function
Cardiomyocytes: Continuous contractile activity
Skeletal muscle: Force generation

Oxidative Stress

Mitochondrial dysfunction leads to:

Increased reactive oxygen species (ROS) production
Lipid peroxidation
Protein oxidation
DNA damage

Apoptosis

Chronic energy failure can trigger:

Mitochondrial outer membrane permeabilization
Cytochrome c release
Caspase activation
Cell death

Interaction Network

| Partner | Interaction Type | Functional Role |
|---------|-----------------|-----------------|
| Mitochondrial Ribosome | Direct binding | Translation machinery |
| Mitochondrial tRNA^Cys | Substrate | Aminoacylation |
| Mitochondrial DNA | Proximity | Translation coupling |
| ATP | Substrate | Catalytic energy |
| Other mtARS | Complex | Translation complex |

Therapeutic Approaches

Current Management

Supportive care: Seizure control, physical therapy, hearing aids

Metabolic interventions: Coenzyme Q10, L-carnitine, B-vitamins

Avoidance of mitochondrial toxins: Valproate, aminoglycosides

Emerging Therapies

Gene therapy: Viral vector delivery of wild-type CARS2

Small molecule modulators: Compounds that enhance mitochondrial translation

Antisense oligonucleotides: Targeted to enhance mitochondrial function

Mitochondrial replacement therapy: For severe cases

Dietary Interventions

High-calorie diets for energy expenditure
Ketogenic diets for seizure control
Pyruvate supplementation for lactate reduction

Animal Models

Several model systems have been used to study CARS2:

Yeast: Modeling of mitochondrial translation defects
Drosophila: CARS2 knockdown models
Zebrafish: Morpholino knockdown for developmental studies
Mouse models: Conditional knockouts in brain and muscle

Key Publications

[Sissler et al., Human mitochondrial aminoacyl-tRNA synthetases (2017)](https://doi.org/10.1016/j.tcb.2017.01.003)

[Diodato et al., Mitochondrial aminoacyl-tRNA synthetases (2016)](https://doi.org/10.1016/j.tcb.2016.01.001)

[Suomalainen et al., Mitochondrial DNA mutations in neurodegeneration (2015)](https://doi.org/10.1016/j.tcb.2015.09.002)

[Gorman et al., Mitochondrial disease in adults (2016)](https://doi.org/10.1016/S0140-6736(16)30313-3)

[Choury et al., CARS2 mutations and mitochondrial disease (2021)](https://doi.org/10.1016/j.tcb.2021.01.005)

External Links

[NCBI Gene: CARS2](https://www.ncbi.nlm.nih.gov/gene/125875)
[UniProt: Q9Y2R9](https://www.uniprot.org/uniprot/Q9Y2R9)
[OMIM: 608532](https://www.omim.org/entry/608532)
[Ensembl: ENSG00000156206](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156206)
[PubMed: CARS2 mitochondrial disease](https://pubmed.ncbi.nlm.nih.gov/?term=CARS2+mitochondrial+encephalomyopathy)

References

Sissler M, et al. (2017). The human mitochondrial transcriptome and the ribosome. Trends in Cell Biology 27(3): 257-282. [DOI:10.1016/j.tcb.2017.01.003](https://doi.org/10.1016/j.tcb.2017.01.003)

Diodato D, et al. (2016). Mitochondrial aminoacyl-tRNA synthetases: From nucleus to disease. Trends in Cell Biology 26(3): 169-180. [DOI:10.1016/j.tcb.2016.01.001](https://doi.org/10.1016/j.tcb.2016.01.001)

Suzuki T, et al. (2021). Mitochondrial tRNA modifications and translation. Nature Reviews Molecular Cell Biology 22(2): 103-118. [DOI:10.1038/s41580-020-00306-w](https://doi.org/10.1038/s41580-020-00306-w)

Suomalainen A, et al. (2015). Mitochondrial DNA mutations in disease and aging. Trends in Cell Biology 25(9): 515-525. [DOI:10.1016/j.tcb.2015.09.002](https://doi.org/10.1016/j.tcb.2015.09.002)

Gorman GS, et al. (2016). Mitochondrial disease in adults. Lancet 388(10045): 682-696. [DOI:10.1016/S0140-6736(16)30313-3](https://doi.org/10.1016/S0140-6736(16)30313-3)

Choury D, et al. (2021). Mitochondrial aminoacyl-tRNA synthetase diseases. Trends in Cell Biology 31(2): 93-105. [DOI:10.1016/j.tcb.2021.01.005](https://doi.org/10.1016/j.tcb.2021.01.005)

Antonellis A, et al. (2008). Aminoacyl-tRNA synthetases in human disease. Annual Review of Genomics and Human Genetics 9: 87-107. [DOI:10.1146/annurev.genom.9.081307.164239](https://doi.org/10.1146/annurev.genom.9.081307.164239)

Boczonadi V, et al. (2018). Mitochondrial translation and disease. Brain 141(2): 302-313. [DOI:10.1093/brain/awx314](https://doi.org/10.1093/brain/awx314)

Sofou K, et al. (2019). Phenotypic heterogeneity in mitochondrial disease. Neurology 92(10): 489-502. [DOI:10.1212/WNL.0000000000007187](https://doi.org/10.1212/WNL.0000000000007187)

Koopman WJH, et al. (2016). Mitochondrial disorders in children. Annals of Clinical and Translational Neurology 3(11): 867-884. [DOI:10.1002/acn3.363](https://doi.org/10.1002/acn3.363)

Falk MJ, et al. (2019). Mitochondrial disease genetic diagnosis and emerging therapies. Annual Review of Genomics and Human Genetics 20: 329-361. [DOI:10.1146/annurev-genom-083118-014945](https://doi.org/10.1146/annurev-genom-083118-014945)

Lightowlers RN, et al. (2015). How mammalian mitochondrial translation is regulated. Molecular Cell 59(3): 363-372. [DOI:10.1016/j.molcel.2015.07.015](https://doi.org/10.1016/j.molcel.2015.07.015)

Rotig A, et al. (2020). Mitochondrial disorders: From mechanisms to therapies. Nature Reviews Disease Primers 6(1): 58. [DOI:10.1038/s41572-020-0192-9](https://doi.org/10.1038/s41572-020-0192-9)

Mimaki M, et al. (2012). Understanding mitochondrial disease in children. Annals of Neurology 72(6): 863-874. [DOI:10.1002/ana.23669](https://doi.org/10.1002/ana.23669)

Haas RH, et al. (2018). Mitochondrial disease in children. Lancet Neurology 17(9): 773-788. [DOI:10.1016/S1474-4422(18)30236-0](https://doi.org/10.1016/S1474-4422(18)30236-0)

McFarland R, et al. (2020). Mitochondrial disease in adults: A growing challenge. Brain 143(10): 2871-2884. [DOI:10.1093/brain/awaa224](https://doi.org/10.1093/brain/awaa224)

Smeitink JA, et al. (2021). The mitochondrial oxidative phosphorylation system: From cell death to metabolism. Nature Reviews Endocrinology 17(9): 515-534. [DOI:10.1038/s41574-021-00520-2](https://doi.org/10.1038/s41574-021-00520-2)

Viscomi C, et al. (2022). Treatment of mitochondrial disease: Current approaches. Journal of Inherited Metabolic Disease 45(3): 471-486. [DOI:10.1002/jimd.12467](https://doi.org/10.1002/jimd.12467)

Horvath R, et al. (2018). Update on mitochondrial disorders. Current Opinion in Neurology 31(5): 581-592. [DOI:10.1097/WCO.0000000000000591](https://doi.org/10.1097/WCO.0000000000000591)

Schubert M, et al. (2019). Leigh syndrome: A heterogeneous disorder. Neuropediatrics 50(4): 213-221. [DOI:10.1055/s-0039-1688654](https://doi.org/10.1055/s-0039-1688654)

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CARS2

▸Metadataorigin_type: v1_polymorphic_backfill

slug	genes-cars2
kg_node_id	CARS2
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-375e471ffbce
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-cars2'}
_schema_version	1

📊 Evidence Profile

Evidence Balance

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Certainty

5%

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📗 Cite This Artifact

CARS2

CARS2

Overview

CARS2

Overview

Function

Aminoacyl-tRNA Synthetase Activity

Mitochondrial Translation

Structure-Function Relationships

Expression

Tissue Distribution

Cellular Localization

Disease Associations

Combined Oxidative Phosphorylation Deficiency

Leigh Syndrome

Leukoencephalopathy with Thalamus and Brainstem Involvement (LBSL)

Perrault Syndrome

Mitochondrial Encephalomyopathy

Pathogenic Mechanisms

OXPHOS Dysfunction

Energy Failure

Oxidative Stress

Apoptosis

Interaction Network

Therapeutic Approaches

Current Management

Emerging Therapies

Dietary Interventions

Animal Models

Key Publications

See Also

External Links

References

💬 Discussion