In vivo study in Trypanosoma brucei links mitochondrial transfer RNA import to mitochondrial protein import.

Trypanosoma brucei imports all mitochondrial transfer RNAs (tRNAs) from the cytosol. By using cell lines that allow independent tetracycline-inducible RNA interference and isopropyl-β-D-thiogalactopyranoside-inducible expression of a tagged tRNA, we show that ablation of Tim17 and mitochondrial heat-shock protein 70, components of the inner-membrane protein translocation machinery, strongly inhibits import of newly synthesized tRNAs. These findings, together with previous results in yeast and plants, suggest that the requirement for mitochondrial protein-import factors might be a conserved feature of mitochondrial tRNA import in all systems.