Dual-targeted tRNA-dependent amidotransferase ensures both mitochondrial and chloroplastic Gln-tRNAGln synthesis in plants.
Aminoacyl-tRNAs are generally formed by direct attachment of an amino acid to tRNAs by aminoacyl-tRNA synthetases, but Gln-tRNA is an exception to this rule. Gln-tRNA(Gln) is formed by this direct pathway in the eukaryotic cytosol and in protists or fungi mitochondria but is formed by an indirect transamidation pathway in most of bacteria, archaea, and chloroplasts. We show here that the formation of Gln-tRNA(Gln) is also achieved by the indirect pathway in plant mitochondria. The mitochondrial-encoded tRNA(Gln), which is the only tRNA(Gln) present in mitochondria, is first charged with glutamate by a nondiscriminating GluRS, then is converted into Gln-tRNA(Gln) by a tRNA-dependent amidotransferase (AdT). The three subunits GatA, GatB, and GatC are imported into mitochondria and assemble into a functional GatCAB AdT. Moreover, the mitochondrial pathway of Gln-tRNA(Gln) formation is shared with chloroplasts as both the GluRS, and the three AdT subunits are dual-imported into mitochondria and chloroplasts.
Pujol
Claire
C
Institut de Biologie Moléculaire des Plantes (Unité Propre de Recherche 2357 du Centre National de la Recherche Scientifique), Université Louis Pasteur-Strasbourg 1, Centre National de la Recherche Scientifique, Strasbourg, France.
Bailly
Marc
M
Kern
Daniel
D
Maréchal-Drouard
Laurence
L
Becker
Hubert
H
Duchêne
Anne-Marie
AM
D017360:Arabidopsis / Q000201:enzymology*; D002457:Cell Extracts; D002736:Chloroplasts / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D005975:Glutamate-tRNA Ligase / Q000378:metabolism; D005973:Glutamine / Q000096:biosynthesis*; D008928:Mitochondria / Q000201:enzymology*; D019884:Nitrogenous Group Transferases / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport; D012346:RNA, Transfer, Amino Acyl / Q000096:biosynthesis*; D011198:Solanum tuberosum / Q000201:enzymology*
D002457:Cell Extracts; D021122:Protein Subunits; D012346:RNA, Transfer, Amino Acyl; D005973:Glutamine; D019884:Nitrogenous Group Transferases; D005975:Glutamate-tRNA Ligase