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Coevolution of specificity determinants in eukaryotic glutamyl- and glutaminyl-tRNA synthetases
- Source :
- Journal of molecular biology. 426(21)
- Publication Year :
- 2014
-
Abstract
- The glutaminyl-tRNA synthetase (GlnRS) enzyme, which pairs glutamine with tRNA(Gln) for protein synthesis, evolved by gene duplication in early eukaryotes from a nondiscriminating glutamyl-tRNA synthetase (GluRS) that aminoacylates both tRNA(Gln) and tRNA(Glu) with glutamate. This ancient GluRS also separately differentiated to exclude tRNA(Gln) as a substrate, and the resulting discriminating GluRS and GlnRS further acquired additional protein domains assisting function in cis (the GlnRS N-terminal Yqey domain) or in trans (the Arc1p protein associating with GluRS). These added domains are absent in contemporary bacterial GlnRS and GluRS. Here, using Saccharomyces cerevisiae enzymes as models, we find that the eukaryote-specific protein domains substantially influence amino acid binding, tRNA binding and aminoacylation efficiency, but they play no role in either specific nucleotide readout or discrimination against noncognate tRNA. Eukaryotic tRNA(Gln) and tRNA(Glu) recognition determinants are found in equivalent positions and are mutually exclusive to a significant degree, with key nucleotides located adjacent to portions of the protein structure that differentiated during the evolution of archaeal nondiscriminating GluRS to GlnRS. These findings provide important corroboration for the evolutionary model and suggest that the added eukaryotic domains arose in response to distinctive selective pressures associated with the greater complexity of the eukaryotic translational apparatus. We also find that the affinity of GluRS for glutamate is significantly increased when Arc1p is not associated with the enzyme. This is consistent with the lower concentration of intracellular glutamate and the dissociation of the Arc1p:GluRS complex upon the diauxic shift to respiratory conditions.
- Subjects :
- Models, Molecular
Protein domain
Saccharomyces cerevisiae
Molecular Sequence Data
Aminoacylation
Biology
Amino Acyl-tRNA Synthetases
Evolution, Molecular
Protein structure
RNA, Transfer
Structural Biology
Sequence Homology, Nucleic Acid
Protein biosynthesis
Anticodon
Amino Acids
Molecular Biology
Phylogeny
Genetics
Base Sequence
Proteins
biology.organism_classification
TRNA binding
Protein Structure, Tertiary
Glutamate-tRNA Ligase
Biochemistry
Transfer RNA
Nucleic Acid Conformation
RNA
Amino acid binding
Allosteric Site
Subjects
Details
- ISSN :
- 10898638
- Volume :
- 426
- Issue :
- 21
- Database :
- OpenAIRE
- Journal :
- Journal of molecular biology
- Accession number :
- edsair.doi.dedup.....1dea771137c9d587f3cffb45a4a96154