In all organisms, aminoacyl tRNA synthetases covalently attach amino acids to their cognate tRNAs. Many eukaryotic tRNA synthetases have acquired appended domains, whose origin, structure and function are poorly understood. The N-terminal appended domain (NTD) of glutaminyl-tRNA synthetase (GlnRS) is intriguing since GlnRS is primarily a eukaryotic enzyme, whereas in other kingdoms Gln-tRNA(Gln...

Eukaryotic tRNAs are synthesized in the nucleus and need to be exported to the cytoplasm where they function in translation. tRNA export is mediated by exportin-t, which binds tRNA directly and with high affinity. tRNAs are initially synthesized as precursor molecules. Maturation to functional tRNA takes place in the nucleus, precedes export, and includes trimming of the 5' and 3' ends, posttra...

The accuracy of protein biosynthesis rests on the high fidelity with which aminoacyl-tRNA synthetases discriminate between tRNAs. Correct aminoacylation depends not only on identity elements (nucleotides in certain positions) in tRNA (1), but also on competition between different synthetases for a given tRNA (2). Here we describe in vivo and in vitro experiments which demonstrate how variations...

The reduction of specific uridines to dihydrouridine is one of the most common modifications in tRNA. Increased levels of the dihydrouridine modification are associated with cancer. Dihydrouridine synthases (Dus) from different subfamilies selectively reduce distinct uridines, located at spatially unique positions of folded tRNA, into dihydrouridine. Because the catalytic center of all Dus enzy...

Messenger RNAs (mRNAs) which lack a stop codon result in ribosomes stalled at the 3’ end of mRNA. Alternative ribosome-rescue factor B (ArfB) rescues by tRNA-peptide hydrolysis and thus releasing peptide. ArfB consists an N-terminal domain with GGQ motif required for hydrolysis, C-terminal acts as sensor empty mRNA entry channel, linker connecting domains. binds to ribosomal A site regardless l...

Aspartyl-tRNA synthetase (AspRS) occurs in two types: the discriminating enzyme (D-AspRS) forms only Asp-tRNA(Asp), whereas the nondiscriminating enzyme (ND-AspRS) also synthesizes Asp-tRNA(Asn), which is a required intermediate for protein synthesis in many organisms. We attempted to expand the tRNA recognition of the discriminating Thermococcus kodakaraensis AspRS to that of a ND-AspRS by in ...

An essential step in the replication of all retroviruses is the capture of a cellular tRNA that is used as the primer for reverse transcription. The 3'-terminal 18 nucleotides of the tRNA are complementary to the primer binding site (PBS). Moloney murine leukemia virus (MuLV) preferentially captures tRNA(Pro). To investigate the specificity of primer selection, the PBS of MuLV was altered to be...

The distribution of cytokinin activity in wheat (Triticum aestivum) germ tRNA fractionated by BD-cellulose and RPC-5 chromatography has been examined. As in other organisms, the cytokinin moieties in wheat germ tRNA appear to be restricted to tRNA species that would be expected to respond to codons beginning with U. Only a few of the wheat germ tRNA species in this coding group actually contain...

The biochemical properties of two species of methionine transfer ribonucleic acid from bakers’ yeast, separated by diethylaminoethyl Sephadex column chromatography, have been studied. Each species of the two methionine tRNAs, designated methionine tRNA I and methionine tRNA II, respectively, has been purified by benzoylated DEAEcellulose column chromatography. Methionine tRNA I can be esterifie...

Transfer RNA is an essential molecule for biologlcal system, and each tRNA molecule commonly has a c]overleaf structure. Previously, we experimentally showed that some Drosophila tRNA (tRNAAia, tRNAHis, artd tRNAMet) molecules fit to form another, non-cloyerleaf, strllcture in which the 3'-half of the tRNA molecules forms an atternatiye hairpin, and that the tRNA molecules are internally cleaye...