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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(More)
It is impossible to predict which pathway, direct glutaminylation of tRNA(Gln) or tRNA-dependent transamidation of glutamyl-tRNA(Gln), generates mitochondrial glutaminyl-tRNA(Gln) for protein synthesis in a given species. The report that yeast mitochondria import both cytosolic glutaminyl-tRNA synthetase and tRNA(Gln) has challenged the widespread use of(More)
In the course of a structural genomics program aiming at solving the structures of Escherichia coli open reading frame products of unknown function, we have determined the structure of YadB at 1.5A using molecular replacement. The YadB protein is 298 amino acid residues long and displays 34% sequence identity with E.coli glutamyl-tRNA synthetase (GluRS). It(More)
Analysis of the completed genome sequences revealed presence in various bacteria of an open reading frame (ORF) encoding a polypeptide chain presenting important similarities with the catalytic domain of glutamyl-tRNA synthetases but deprived of the C-terminal anticodon-binding domain. This paralog of glutamyl-tRNA synthetases, the YadB protein, activates(More)
Asparagine, one of the 22 genetically encoded amino acids, can be synthesized by a tRNA-dependent mechanism. So far, this type of pathway was believed to proceed via two independent steps. A nondiscriminating aspartyl-tRNA synthetase (ND-DRS) first generates a mischarged aspartyl-tRNAAsn that dissociates from the enzyme and binds to a tRNA-dependent(More)
Faithful protein synthesis relies on a family of essential enzymes called aminoacyl-tRNA synthetases, assembled in a piecewise fashion. Analysis of the completed archaeal genomes reveals that all archaea that possess asparaginyl-tRNA synthetase (AsnRS) also display a second ORF encoding an AsnRS truncated from its anticodon binding-domain (AsnRS2). We show(More)
In most prokaryotes Asn-tRNA(Asn) and Gln-tRNA(Gln) are formed by amidation of aspartate and glutamate mischarged onto tRNA(Asn) and tRNA(Gln), respectively. Coexistence in the organism of mischarged Asp-tRNA(Asn) and Glu-tRNA(Gln) and the homologous Asn-tRNA(Asn) and Gln-tRNA(Gln) does not, however, lead to erroneous incorporation of Asp and Glu into(More)
Dynamic light scattering (DLS) analyses are routinely used in biology laboratories to detect aggregates in macromolecular solutions, to determine the size of proteins, nucleic acids, and complexes or to monitor the binding of ligands. This article is written for graduate and undergraduate students with access to DLS and for faculty members who wish to(More)
In many prokaryotes and in organelles asparagine and glutamine are formed by a tRNA-dependent amidotransferase (AdT) that catalyzes amidation of aspartate and glutamate, respectively, mischarged on tRNAAsn and tRNAGln. These pathways supply the deficiency of the organism in asparaginyl- and glutaminyl-tRNA synthtetases and provide the translational(More)
In most organisms, tRNA aminoacylation is ensured by 20 aminoacyl-tRNA synthetases (aaRSs). In eubacteria, however, synthetases can be duplicated as in Thermus thermophilus, which contains two distinct AspRSs. While AspRS-1 is specific, AspRS-2 is non-discriminating and aspartylates tRNA(Asp) and tRNA(Asn). The structure at 2.3 A resolution of AspRS-2, the(More)