The human pathogen Staphylococcus aureus is an asparagine prototroph despite its genome not encoding an asparagine synthetase. S. aureus does use an asparaginyl-tRNA synthetase (AsnRS) to directly ligate asparagine to tRNA(Asn). The S. aureus genome also codes for one aspartyl-tRNA synthetase (AspRS). Here we demonstrate the lone S. aureus aspartyl-tRNA synthetase has relaxed tRNA specificity a...

BACKGROUND Transfer RNA (tRNA) gene predictions are complicated by challenges such as structural variation, limited sequence conservation and the presence of highly reiterated short interspersed sequences (SINEs) that originally derived from tRNA genes or tRNA-like transcription units. Annotation of "tRNA genes" in sequenced genomes generally have not been accompanied by experimental verificati...

Yeast mitochondria contain a minimalist threonyl-tRNA synthetase (ThrRS) composed only of the catalytic core and tRNA binding domain but lacking the entire editing domain. Besides the usual tRNA(Thr)2, some budding yeasts, such as Saccharomyces cerevisiae, also contain a non-canonical tRNA(Thr)1 with an enlarged 8-nucleotide anticodon loop, reprograming the usual leucine CUN codons to threonine...

The accessibility of phosphates towards ethylnitrosourea was studied in tRNA/aminoacyl-.tRNA synthetase complexes and in the ternary aminoacyltRNA/EF-Tu/GTP complex. When the tRNA is complexed to aminoacyl-tRNA synthetases, several phosphates are protected against the alkylation agent, the protection patterns varying according to the tRNA/aminoacyl-tRNA synthetase system. However in all cases p...

Purified yeast phenylalanyl-tRNA synthetase can aminoacylate (yeast) tRNA(Phe), (wheat) tRNA(Phe), and (Escherichia coli) tRNA(1) (Val) (1, 2). We now report that this synthetase can also aminoacylate (E. coli) tRNA(Phe) and (E. coli) tRNA(1) (Ala). Highly purified (E. coli) tRNA(Phe) is heterologously aminoacylated to approximately 90% of the extent achieved with the homologous enzyme (crude E...

Mutants of Escherichia coli defective only in the biosynthesis of 5-methyluridine (ribothymidine) in their transfer ribonucleic acid (tRNA) were employed to investigate whether phage T4 induces its own tRNA(mV)methylase and whether T4-specific tRNA contains 5-methyluridine. The amounts of other methylated derivatives in the T4-specific tRNA were also determined. The results establish that T4-sp...

The initiation of human immunodeficiency virus type 1 (HIV-1) reverse transcription occurs at the primer binding site (PBS) that is complementary to the 3'-terminal nucleotides of tRNA(3)(Lys). Why all known strains of HIV-1 select tRNA(3)(Lys) for replication is unknown. Previous studies on the effect of altering the PBS of HIV-1 on replication identified an HIV-1 with a PBS complementary to t...

Satellite tobacco necrosis virus RNA directs the ribosomal binding of methionyl-, alanyl-, and lysyl-tRNA when incubated under the appropriate conditions in the in vitro wheat embryo amino acid incorporating system. The products of the various binding reactions have been identified as methionyl-tRNA, methionyl-alanyl-tRNA, and methionyl-alanyllysyl-tRNA. This sequence corresponds to the known N...

Los1p, the Saccharomyces cerevisiae exportin-t homologue, binds tRNA and functions in pre-tRNA splicing and export of mature tRNA from the nucleus to the cytosol. Because LOS1 is unessential in yeast, other pathways for tRNA nuclear export must exist. We report that Cca1p, which adds nucleotides C, C, and A to the 3' end of tRNAs, is a multicopy suppressor of the defect in tRNA nuclear export c...

The limited locations of tRNA introns are crucial for eukaryal tRNA-splicing endonuclease recognition. However, our analysis of the nuclear genome of an early-diverged red alga, Cyanidioschyzon merolae, demonstrated the first evidence of nuclear-encoded tRNA genes that contain ectopic and/or multiple introns. Some genes exhibited both intronic and permuted structures in which the 3'-half of the...