YARS2 (Tyrosyl-tRNA Synthetase 2, Mitochondrial) encodes a mitochondrial aminoacyl-tRNA synthetase (mtaaRS) that catalyzes the attachment of tyrosine to its cognate mitochondrial tRNA during mitochondrial translation. This enzyme is essential for the proper synthesis of mitochondrial-encoded proteins, which are critical components of the oxidative phosphorylation (OXPHOS) system. Mutations in YARS2 cause Myopathy, Lactic Acidosis, and Sideroblastic Anemia (MLASA) syndrome, a rare autosomal recessive mitochondrial disorder characterized by exercise intolerance, muscle weakness, and sideroblastic anemia[1]. Beyond its role in MLASA, emerging evidence suggests that YARS2 and other mitochondrial aminoacyl-tRNA synthetases may contribute to the pathogenesis of common neurodegenerative diseases including Alzheimer's disease and Parkinson's disease through their effects on mitochondrial protein synthesis and cellular energy metabolism[2].
Mitochondrial dysfunction is a hallmark of neurodegeneration, with defects in mitochondrial translation increasingly recognized as important contributors to disease progression. YARS2, as a key component of the mitochondrial translation machinery, represents a potential link between mitochondrial dysfunction and neurodegenerative processes.
The YARS2 gene is located on chromosome 12p11.21 and spans approximately 12 kilobases. The gene consists of 13 exons that encode a 495-amino acid protein. The genomic structure is relatively conserved among mammalian species, with the coding sequence distributed across multiple exons.
YARS2 belongs to the class II aminoacyl-tRNA synthetase family and shows high evolutionary conservation:
The mitochondrial targeting sequence at the N-terminus (approximately 30-40 amino acids) directs the protein to the mitochondrial matrix, where it is processed to the mature form.
Multiple splice variants of YARS2 have been identified, though their functional significance varies. Some variants may produce proteins with altered subcellular localization or stability.
YARS2 is a monomeric mitochondrial enzyme that performs the following functions:
YARS2 catalyzes a two-step aminoacylation reaction:
This reaction requires:
YARS2 contains several important structural features:
YARS2, like other mtaaRSs, has quality control mechanisms:
Mitochondrial translation is essential for producing the 13 oxidative phosphorylation (OXPHOS) complex subunits encoded by mitochondrial DNA. YARS2 plays a critical role in this process:
Proper mitochondrial translation produces:
Defects in any of these complexes can impair energy production.
MLASA is a rare autosomal recessive mitochondrial disorder caused by YARS2 mutations[1:1][3]:
Emerging evidence links YARS2 dysfunction to Alzheimer's disease pathogenesis[4][5]:
YARS2 may also be relevant to Parkinson's disease[6]:
YARS2 and mitochondrial translation have been implicated in ALS[7]:
YARS2 exhibits tissue-specific expression:
| Tissue | Expression Level |
|---|---|
| Skeletal muscle | Highest |
| Heart | High |
| Brain | Moderate |
| Liver | Moderate |
| Kidney | Lower |
In the brain, YARS2 is expressed in:
The high expression in muscle and heart reflects the high mitochondrial content in these tissues.
YARS2 supports OXPHOS through mitochondrial translation:
Mitochondrial function affects ROS production:
Mitochondria buffer cytosolic calcium:
Mitochondria are central to apoptosis:
YARS2 is an essential mitochondrial aminoacyl-tRNA synthetase that charges mitochondrial tRNA^Tyr with tyrosine, enabling proper mitochondrial translation. Mutations in YARS2 cause MLASA syndrome, a mitochondrial disorder with myopathy, lactic acidosis, and sideroblastic anemia. Beyond this rare disease, YARS2 dysfunction may contribute to common neurodegenerative diseases through its effects on mitochondrial protein synthesis and oxidative phosphorylation. The growing understanding of YARS2's role in mitochondrial function suggests that targeting this enzyme and related mitochondrial translation pathways may have therapeutic potential for Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions.
MLASA syndrome: Clinical features and molecular basis (Orphanet Journal of Rare Diseases, 2019). 2019. ↩︎ ↩︎
Mitochondrial translation and neurodegenerative disease (Nature Reviews Neuroscience, 2021). 2021. ↩︎
YARS2 mutations in mitochondrial disease (Brain, 2018). 2018. ↩︎
Mitochondrial dysfunction in Alzheimer's disease (Progress in Lipid Research, 2021). 2021. ↩︎
Aminoacyl-tRNA synthetases in neurodegeneration (Cell, 2020). 2020. ↩︎
Oxidative stress and mitochondrial dysfunction in Parkinson's disease (Antioxidants & Redox Signaling, 2022). 2022. ↩︎
Mitochondrial translation defects in ALS (Acta Neuropathologica, 2023). 2023. ↩︎