Article
- The EMBO Journal (2007) 26, 4302 - 4312
- doi:10.1038/sj.emboj.7601857
Published online: 13 September 2007
Subject Categories:
Elongation factor 1a mediates the specificity of mitochondrial tRNA import in T. brucei
Nabile Bouzaidi-Tiali1,a, Eric Aeby1,a, Fabien Charrière1,a, Mascha Pusnik1 and André Schneider1
- Department of Biology/Cell and Developmental Biology, University of Fribourg, Chemin du Musée 10, Fribourg, Switzerland
Correspondence to:
André Schneider, Department of Biology, University of Fribourg, Chemin du Musee 10, Fribourg 1700, Switzerland. Tel.: +41 26 300 8877; Fax: +41 26 300 9741; E-mail: andre.schneider@unifr.ch
aThese authors contributed equally to this work
Received 7 February 2007; Accepted 22 August 2007
Abstract
Mitochondrial tRNA import is widespread in eukaryotes. Yet, the mechanism that determines its specificity is unknown. Previous in vivo experiments using the tRNAsMet, tRNAIle and tRNALys have suggested that the T-stem nucleotide pair 51:63 is the main localization determinant of tRNAs in Trypanosoma brucei. In the cytosol-specific initiator tRNAMet, this nucleotide pair is identical to the main antideterminant that prevents interaction with cytosolic elongation factor (eEF1a). Here we show that ablation of cytosolic eEF1a, but not of initiation factor 2, inhibits mitochondrial import of newly synthesized tRNAs well before translation or growth is affected. tRNASec is the only other cytosol-specific tRNA in T. brucei. It has its own elongation factor and does not bind eEF1a. However, a mutant of the tRNASec expected to bind to eEF1a is imported into mitochondria. This import requires eEF1a and aminoacylation of the tRNA. Thus, for a tRNA to be imported into the mitochondrion of T. brucei, it needs to bind eEF1a, and it is this interaction that mediates the import specificity.
Keywords:
- elongation factor1a,
- mitochondrial biogenesis,
- selenocysteine tRNA,
- tRNA,
- trypanosomes
