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Saccharomyces cerevisiae imports the cytosolic pathway for Gln‐tRNA synthesis into the mitochondrion
Author(s) -
Krett Bethany Ann,
Rinehart Jesse,
Rubio Mary Anne T.,
Alfonzo Juan D.,
Söll Dieter
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a500-b
Subject(s) - transfer rna , mitochondrion , biochemistry , biology , translation (biology) , saccharomyces cerevisiae , protein biosynthesis , aminoacyl trna , cytosol , aminoacyl trna synthetase , amino acid , cytoplasm , yeast , enzyme , rna , gene , messenger rna
Aminoacyl‐tRNA formation, an essential process in protein biosynthesis, is generally achieved by direct attachment of an amino acid to tRNA by the aminoacyl‐tRNA synthetases. An exception is Gln‐tRNA synthesis, which in eukaryotes is catalyzed by glutaminyl‐tRNA synthetase (GlnRS), while most bacteria, archaea and chloroplasts employ the transamidation pathway, in which a tRNA‐dependent glutamate modification generates Gln‐tRNA. It is known that a complete set of tRNAs is encoded in yeast mitochondrial DNA. Early work suggested that mitochondria employ transamidation for Gln‐tRNA formation. However, we showed in vivo mitochondrial localization of the nuclear encoded tRNA Gln as well as of the cytoplasmic GlnRS. We also demonstrated that the imported tRNA Gln can be used in mitochondrial translation. In addition, in vitro reconstitution of the cytoplasmic tRNA Gln import into mitochondria reveals a novel import mechanism. We are currently investigating the roles played by the imported and mitochondrial encoded tRNA Gln species in mitochondrial translation. Import of both cytoplasmic components for Gln‐tRNA suggests that the transamidation pathway, whose enzymes are encoded in the genome, may be conserved for an alternate function. These findings thus change our view of the evolution of organellar protein synthesis. This work was supported by a grant from NIGMS, National Institutes of Health.