In many bacteria and archaea, an ancestral pathway is used where asparagine and glutamine are formed from their acidic precursors while covalently linked to tRNA(Asn) and tRNA(Gln), respectively. Stable complexes formed by the enzymes of these indirect tRNA aminoacylation pathways are found in several thermophilic organisms, and are called transamidosomes. We describe here a transamidosome form...

The suppression of an amber mutation in a permissive strain of Escherichia coli can be achieved by a new tRNA species, a suppressor tRNA (for a review, see Reference 1). The tyrosine amber suppressor tRNA arises from a redundant tRNA species in the Sustrain by a single base change in the anticodon (2). However, this may not be the only mechanism to generate suppressor tRNA species, as suggested...

Understanding the mechanistic basis of the disruption of tRNA genes, as manifested in the intron-containing and split tRNAs found in Archaea, will provide considerable insight into the evolution of the tRNA molecule. However, the evolutionary processes underlying these disruptions have not yet been identified. Previously, a composite genome of the deep-branching archaeon Caldiarchaeum subterran...

The suppression of an amber mutation in a permissive strain of Escherichia coli can be achieved by a new tRNA species, a suppressor tRNA (for a review, see Reference 1). The tyrosine amber suppressor tRNA arises from a redundant tRNA species in the Sustrain by a single base change in the anticodon (2). However, this may not be the only mechanism to generate suppressor tRNA species, as suggested...

Pyrrolysine, the 22nd cotranslationally inserted amino acid, was found in the Methanosarcina barkeri monomethylamine methyltransferase protein in a position that is encoded by an in-frame UAG stop codon in the mRNA. M. barkeri encodes a special amber suppressor tRNA (tRNA(Pyl)) that presumably recognizes this UAG codon. It was reported that Lys-tRNA(Pyl) can be formed by the aminoacyl-tRNA synt...

Three tRNA genes have been isolated from a genomic library of Arabidopsis thaliana: a tRNA (GCU), a tRNA (GUA) and a tRNA (UUC) genes. These genes are located closely on the same DNA fragment. The tRNA and the tRNA genes have both 99% sequence similarity with their mitochondrial counterparts from higher plants indicating that these three tRNA genes are mitochondrial. The tRNAv gene shows a part...

Accurate aminoacylation of tRNAs by the aminoacyl-tRNA synthetases (aaRSs) plays a critical role in protein translation. However, some of the aaRSs are missing in many microorganisms. Helicobacter pylori does not have a glutaminyl-tRNA synthetase (GlnRS) but has two divergent glutamyl-tRNA synthetases: GluRS1 and GluRS2. Like a canonical GluRS, GluRS1 aminoacylates tRNA(Glu1) and tRNA(Glu2). In...

The mammalian mitochondrial genome contains a single tRNA(Met) gene that gives rise to the initiator and elongator tRNA(Met). It is generally believed that mitochondrial protein synthesis begins with formylmethionyl-tRNA, which indicates that the formylation of mitochondrial Met-tRNA specifies its participation in initiation through its interaction with initiation factor 2 (IF-2). However, rece...

We compare the diversity of chromosomal-encoded transfer RNA (tRNA) genes from 11 eukaryotes as identified by tRNAScan-SE of their respective genomes. They include the budding and fission yeast, worm, fruit fly, fugu, chicken, dog, rat, mouse, chimp and human. The number of tRNA genes are between 170 and 570 and the number of tRNA isoacceptors range from 41 to 55. Unexpectedly, the number of tR...

Mitochondrial DNA (mtDNA) regions corresponding to two major tRNA gene clusters were amplified and sequenced for the Japanese pit viper, himehabu. In one of these clusters, which in most vertebrates characterized to date contains three tightly connected genes for tRNA(Ile), and tRNA(Gln), and tRNA(Met), a sequence of approximately 1.3 kb was found to be inserted between the genes for tRNA(Ile) ...