Sequence dependence of tRNAGly import into tobacco mitochondria

Plant mitochondrial genomes lack a number of tRNA genes and the corresponding tRNAs, which are nuclear-encoded, are imported from the cytosol. We show that specific import of tRNAGly isoacceptors occurs in tobacco mitochondria: tRNAGly(UCC) and tRNAGly(CCC) are cytosolic and mitochondrial, while tRNAGly(GCC) is found only in the cytosol. Exchange of sequences between tRNAGly(UCC) and tRNAGly(GCC) shows that the anticodon and D-domain are essential for tRNAGly(UCC) import. However the reverse mutations in tRNAGly(GCC) are not sufficient to promote its import into tobacco mitochondria.