Impact of pseudouridylation on mitochondrial tRNA recognition by cognate synthetase
Mitochondrial tRNAs (mt-tRNAs) undergo an extensive post-transcriptional modification. One such common modification is pseudouridylation, the conversion of uridine to a 5’-ribosyl isomer of uridine. Although it is the most abundant modified nucleoside to be known in RNA, in most cases the contribution of this modification to the translation process is not clear. Previous research conducted, by Levi O and Arava YS, in our lab has shown that pseudouridine in cytosolic tRNA affects the regulation of translation. Specifically, the deletion of Pus6 resulted in a reduction of MetRS binding to tRNAMet. Yet no studies have been conducted to test this on mt-tRNAs. Here we analyzed this impact by removal of specific pseudouridine enzymes that worked on several mt-tRNAs (tRNAArg, tRNALys, tRNASer). We generated yeast strains deleted of these enzymes: Pus2, Pus4, Pus6, or Pus9. We tested the in vivo impact on the binding of each tRNA to its cognate aminoacyl tRNA synthetase (aaRS). Our results show that Pus4 plays a role in the SerRS binding tRNASer and tRNALys, Pus6 deletion impacts the LysRS binding to tRNASer, and Pus4 deletion impacts the binding of ArgRS to non-cognate tRNAs. This study presents the first in vivo characterization of pseudouridylation impact on mt-tRNA binding to cognate mt-aaRS, shedding new light on the role of this modification in mitochondrial translation regulation.
