Impact of pseudouridylation on mitochondrial tRNA recognition by cognate synthetase and charging

Mitochondrial tRNAs (mt-tRNAs) undergo an extensive post-transcriptional modification. One such common modification is pseudouridylation, the 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. Recent studies have shown that pseudouridine in cytosolic tRNAs affect regulation of translation. Yet no studies have been conducted to test this on mitochondrial tRNAs (mt-tRNAs). Here we analyzed the impact by removal of specific pseudouridines from several mt-tRNAs (tRNAArg, tRNALys, tRNASer, tRNATrp). We generated yeast strains deleted of their corresponding mitochondrial tRNA synthetase: Pus2, Pus4, Pus6 or Pus9 and tested the in vivo impact on binding of each tRNAs to its cognate aminoacyl tRNA synthetase (aaRS). Moreover, aminoacylation status of each tRNA upon Pus deletion was determined.

This study presents the first in vivo characterization of pseudouridylation impact on tRNA binding to cognate aaRS and thus it`s charging, providing important insights for its contribution to the mitochondrial translation process.