Involvement of Imported TRNA in Intramitochondrial Translation

摘要

These studies show that only 10 out of 36 mitochondrial tRNAs hybridize to mtDNA. Consistent with previous observations, Arg, Ile, Lys, Val tRNAs must be imported cytoplasmic tRNAs, since these tRNAs do not hybridize to mtDNA. The evident indicates that these imported tRNAs in Tetrahymena mitochondria are not contaminating cytoplasmic tRNAs in our mitochondrial preparations. The conclusion that they function in intramitochondrial translation is based on the demonstration that all the native and imported tRNAs are associated with the functinal mitochondrial 80S monosome as well as with carefully washed 55S subunits. As expected if they function in translation, all these tRNAs on the ribosomes should become acylated when mitochondria are engaged in protein synthesis. From the codon recognition patterns determined previously, it is quite probable that Tetrahymena mitochondrial translation system differs from mammalian and fungal mitochondrial systems. The mechanisms for transporting tRNA into mitochondria is not known. However, it was proposed earlier that the corresponding tRNA synthetase may act as transport protein. (ERA citation 07:048116)