Overlapping destinations for two dual targeted Glycyl-tRNA synthetases in Arabidopsis thaliana and Phaseolus vulgaris
Résumé
In plant mitochondria, some of the tRNAs are encoded by the mitochondrial genome and resemble their prokaryotic counterparts, whereas the remaining tRNAs are encoded by the nuclear genome and imported from the cytosol. Generally, mitochondrial isoacceptor tRNAs all have the same genetic origin. One known exception to this rule is the group of tRNAGly isoacceptors in dicotyledonous plants. A mitochondrion-encoded tRNAGly and at least one nucleus-encoded tRNAGly coexist in the mitochondria of these plants, and both are required to allow translation of all four GGN glycine codons. We have taken advantage of this atypical situation to address the problem of tRNA/aminoacyl-tRNA synthetase coevolution in plants. In this work, we show that two different nucleus-encoded glycyl-tRNA synthetases (GlyRSs) are imported into Arabidopsis thalianaand Phaseolus vulgaris mitochondria. The first one, GlyRS-1, is similar to human or yeast glycyl-tRNA synthetase, whereas the second, GlyRS-2, is similar to Escherichia coliglycyl-tRNA synthetase. Both enzymes are dual targeted, GlyRS-1 to mitochondria and to the cytosol and GlyRS-2 to mitochondria and chloroplasts. Unexpectedly, GlyRS-1 seems to be active in the cytosol but inactive in mitochondrial fractions, whereas GlyRS-2 is likely to glycylate both the organelle-encoded tRNAGly and the imported tRNAGly present in mitochondria.
Domaines
Biochimie [q-bio.BM]
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...