Disease relevance of tRNA-Tyr

• The structure of tRNATyr halves joined by an E. coli extract was examined [1].

High impact information on tRNA-Tyr

• Whereas mutations were generally rather uniformly distributed throughout the tRNATyr coding sequence, none occurred in the DNA sequences flanking the mature tRNATyr sequence or in a 12 nucleotide sequence including the 10 bp which constitute the 3' side of the intervening sequence [2].
• Twenty-nine different SUP4-o tRNATyr genes with second-site mutations were transcribed in X. laevis cell-free RNA polymerase III transcription reactions, and the in vitro transcripts were analyzed by polyacrylamide gel electrophoresis [3].
• The tRNATyr and tRNAPhe precursors were analyzed by oligonucleotide mapping; they each contain the intervening sequence and fully matured 5' and 3' termini [4].
• Substrates of the synthetase, tRNATyr and tyrosine, interfere with stimulation of tRNA synthesis [5].
• The hyper-modified nucleoside Q (queuosine) is exclusively located in the wobbling position of anticodons of tRNATyr tRNAHis, tRNAAsn and tRNAAsp that recognise codons NAUC (ref. 1). Queuosine and its hexose-containing derivatives are widely distributed in microorganisms, animals and plants [6].

Chemical compound and disease context of tRNA-Tyr

• Electron-spin resonance (ESR) spectra of a nitroxide spin-label attached to residue i6A-37 of yeast tRNATyr were measured in complexes of deacylated tRNATyr with Escherichia coli ribosomes [7].

Biological context of tRNA-Tyr

• All four genes contain, immediately to the 3' side of the anticodon triplet, a 14 base pair tract that is not present in mature tRNATyr [8].
• Although the four genes, which represent three unlinked chromosomal loci, all encode the same mature tRNA sequence, there is virtually no observable sequence homology between the three loci in the region preceding the 5' end of the mature tRNATyr sequences [8].
• This ochre-suppressing tRNATyr gene was cloned into a S. cerevisiae centromeric plasmid, and its level of in vivo expression was monitored by observing the suppressor phenotype of the gene after transformation into S. cerevisiae [9].
• By contrast, point mutations in the A block element of the tRNATyr promoter have less than 2-fold effects on K8; however, total deletion of A block sequences reduces K8 2- to 5-fold [10].
• Mutations which decrease tRNATyr homology to the recognized B block consensus sequence drastically reduce K8 (43- to 370-fold), while mutations which increase homology increase K8 (4- to 5-fold) [10].

Anatomical context of tRNA-Tyr

• A human and a plant intron-containing tRNATyr gene are both transcribed in a HeLa cell extract but spliced along different pathways [11].
• The in vivo tRNA Tyr precursors detected in these studies also appear similar with the RNA species identified when cloned yeast tRNA Tyr is transcribed and processed by Xenopus oocytes and/or Xenopus extracts [12].
• In tRNAAsp (anticodon QUC) and tRNATyr (anticodon Q psi A) from certain eukaryotic cells, the nucleoside Q-34 is further hypermodified into a glycosylated derivative by tRNA-queuine glycosyltransferase [13].

Associations of tRNA-Tyr with chemical compounds

• Nine of fifteen amino acids known to be involved in the formation of the tyrosyl-adenylate complex in B. stearothermophilus are conserved across all of the organisms, whereas amino acids involved in the recognition of tRNATyr are not conserved [14].
• In several, but not all mutant strains, the concentrations of queuine and the Q(+) (queuine-containing) form of tRNATyr are correlated [15].
• This tRNA (adenine-1) methyltransferase converts quantitatively the 3'-terminal adenosine-residue in the dihydrouridine-loop of tRNAThr and tRNATyr from yeast into m1A [16].
• Eucaryotic tRNAThr and tRNATyr from yeast in which 1-methyladenosine (m1A) is already present in the TpsiC loop, can be methylated in vitro with S-adenosylmethionine and B. subtilis extracts [17].
• In addition, tRNATyr modified to have a phenylalanine anticodon was shown to be misacylated by yeast phenylalanyl-tRNA synthetase at a rate at least 10 times faster than unmodified tRNATyr [18].

Other interactions of tRNA-Tyr

• tRNATyr and tRNASer purified from bulk brewer's yeast tRNA were subjected to analysis by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry [19].
• Prokaryotes have three amino acid-specific class II tRNAs that possess a characteristic long variable arm, tRNASer, tRNALeuand tRNATyr, while eukaryotes have only two, tRNASerand tRNALeu [20].
• They are: m5C in tRNA1Gly, m1I in all tRNAAla species, polar A and U called X in tRNATyr, polar U derivative in tRNAGly2, mt6A in tRNASer1 and i6A tRNA2Ser [21].
• In the case of the phenylalanyl system, the crucial role of the wybutine residue (adjacent to the anticodon) in the activation of phenylalanyl-tRNA synthetase by the tRNA core has been analysed by comparison with native or modified non-cognate tRNAs (tRNATyr, tRNAArg) [22].

Analytical, diagnostic and therapeutic context of tRNA-Tyr

• The immobilization of the spin label upon ternary complex formation shows a conformational change of the anticodon region, although this part of tRNATyr is not in direct contact with the protein, as indicated by RNase T1 digestion [23].

References