Impact of alanyl-tRNA synthetase editing deficiency in yeast

Aminoacyl-tRNA synthetases (aaRSs) are essential enzymes that provide the ribosome with aminoacyl-tRNA substrates for protein synthesis. Mutations in aaRSs lead to various neurological disorders in humans. Many aaRSs utilize editing to prevent error propagation during translation. Editing defects in alanyl-tRNA synthetase (AlaRS) cause neurodegeneration and cardioproteinopathy in mice and are associated with microcephaly in human patients. The cellular impact of AlaRS editing deficiency in eukaryotes remains unclear. Here we use yeast as a model organism to systematically investigate the physiological role of AlaRS editing. Our RNA sequencing and quantitative proteomics results reveal that AlaRS editing defects surprisingly activate the general amino acid control pathway and attenuate the heatshock response. We have confirmed these results with reporter and growth assays. In addition, AlaRS editing defects downregulate carbon metabolism and attenuate protein synthesis. Supplying yeast cells with extra carbon source partially rescues the heat sensitivity caused by AlaRS editing deficiency. These findings are in stark contrast with the cellular effects caused by editing deficiency in other aaRSs. Our study therefore highlights the idiosyncratic role of AlaRS editing compared with other aaRSs and provides a model for the physiological impact caused by the lack of AlaRS editing.

Automated summary

Aminoacyl-tRNA synthetases are crucial enzymes for protein synthesis, and mutations in these enzymes can lead to neurological disorders. Editing defects in alanyl-tRNA synthetase (AlaRS) cause neurodegeneration in mice and microcephaly in humans, but the cellular impact in eukaryotes is not well understood. This study reveals that AlaRS editing defects activate the general amino acid control pathway, attenuate the heatshock response, downregulate carbon metabolism, and inhibit protein synthesis in yeast cells, contrasting with effects seen in other aaRSs editing deficiencies. Supplying extra carbon source partially rescues the heat sensitivity caused by AlaRS editing deficiency.