Disease relevance of Aminoacylation

• Here we present data demonstrating that addition of neomycin B inhibited aminoacylation of E. coli tRNA(Phe) in the mid microM range [1].
• The results indicate that amplification of turnip yellow mosaic virus RNA requires aminoacylation, but that neither the natural (valine) specificity nor interaction specifically with valyl-tRNA synthetase is crucial [2].
• Lysyl-tRNA synthetase from Bacillus stearothermophilus (B.s. LysRS) (EC ) catalyzes aminoacylation of tRNA(Lys) with l-lysine, in which l-lysine was first activated with ATP to yield an enzyme (lysyladenylate complex), and then the lysine molecule was transferred from the complex to tRNA(Lys) [3].
• The kinetical analyses of the aminoacylation reaction of tRNA(UUALeu) with S.lividans and E.coli leucyl-tRNA synthetase (LeuRS) suggest there is a unique recognition mechanism of Streptomyces LeuRS toward tRNA(UUALeu) [4].
• Because TyrTS(E152A) was active for the aminoacylation of tRNATyr, its toxicity could only be due to faulty interactions with non-cognate tRNAs, either their non-productive binding or their mischarging with tyrosine [5].

High impact information on Aminoacylation

• Biochemical experiments and genetic complementation in yeast show partial loss of aminoacylation activity of the mutant proteins, and mutations in YARS, or in its yeast ortholog TYS1, reduce yeast growth [6].
• The analog is bound in a pocket, where Pro(41) allows accommodation of the Val and Thr moieties but precludes the Ile moiety (the first sieve), on the aminoacylation domain [7].
• The existence of this protein contrasts with proposals that aminoacylation with cysteine in M. jannaschii is an auxiliary function of a canonical prolyl-tRNA synthetase [8].
• Multiple substitutions in many distinct parts of the molecule do not prevent aminoacylation with alanine [9].
• The enzyme, isoleucyl-transfer RNA synthetase, activates not only the cognate substrate L-isoleucine but also the minimally distinct L-valine in the first, aminoacylation step [10].

Chemical compound and disease context of Aminoacylation

• We show that an aminoacylated amber suppressor tRNA (supF) derived from the E. coli tyrosine tRNA can be imported into COS1 cells and acts as a suppressor of amber codons, whereas the same suppressor tRNA imported without prior aminoacylation does not, suggesting that the supF tRNA is not a substrate for any mammalian aminoacyl-tRNA synthetase [11].
• Early fusion events between ancestral genes for the leucine-specific binding protein and leucyl-tRNA synthetase could account for the similarity and suggest that processes of aminoacylation and transport for leucine in E. coli may be performed by evolutionarily interrelated proteins [12].
• Site of aminoacylation of tRNAs from Escherichia coli with respect to the 2'- or 3'-hydroxyl group of the terminal adenosine [13].
• This tryptic fragment is similar in size and sequence to Escherichia coli glutamine tRNA synthetase and shows a modest increase from the full-length yeast enzyme in the Km values for glutamine and ATP and no difference in the kcat for aminoacylation or the Km for tRNA [14].
• Alteration of the kinetic parameters for aminoacylation of Escherichia coli formylmethionine transfer RNA by modification of an anticodon base [15].

Biological context of Aminoacylation

• Substitution of the G3.U70 base pair with G3.C70 or A3.U70 in the acceptor helix prevents aminoacylation in vivo and in vitro, however, and the introduction of this base pair into tRNA(Cys) (ref. 1) or tRNA(Phe) (refs 1, 2) enables both to accept alanine [9].
• The aminoacylation of synthetic tDNAs demonstrates that the ribose backbone of a tRNA is not absolutely required for tRNA aminoacylation [16].
• Steady-state aminoacylation kinetics of unmodified yeast tRNA(Asp) transcript indicate that the complex between tRNA(Asp) and tobramycin is a competitive inhibitor of the aspartylation reaction with an inhibition constant (K(I)) of 36 nM [17].
• The crystal structures of the various complexes formed by yeast aspartyl-tRNA synthetase (AspRS) and its substrates provide snapshots of the active site corresponding to different steps of the aminoacylation reaction [18].
• Although the fusion proteins lacked the RNA sequence specificity of the natural enzyme, their activity was within 1-2 kcal.mol(-1) of a truncated alanyl-tRNA synthetase that has aminoacylation activity sufficient to sustain cell growth [19].

Anatomical context of Aminoacylation

• Therefore, several lines of evidence indicate that the protein synthesis defect in A3243G MELAS mutation-carrying cells is mainly due to a reduced association of mRNA with ribosomes, possibly as a consequence of the tRNA(Leu(UUR)) aminoacylation defect [20].
• Similarly to the yeast system, tRNA(Lys) import into human mitochondria depended on aminoacylation and on the precursor of the mitochondrial lysyl-tRNA synthetase [21].
• Kinetic evidence for half-of-the-sites reactivity in tRNATrp aminoacylation by tryptophanyl-tRNA synthetase from beef pancreas [22].
• Further, marcaine inhibited aminoacylation in cell-free systems using components from several mammalian tissues, including muscle, from yeast, and from wheat germ [23].
• In bacteria, archaea and eukaryotic organelles, the formation of Gln-tRNA(Gln) is prevalently accomplished by a transamidation pathway, aminoacylation of tRNA(Gln) with Glu by glutamyl-tRNA synthetase (GluRS) followed by a tRNA-dependent transamidation of Glu from Glu-tRNA(Gln) [24].

Associations of Aminoacylation with chemical compounds

• The anticodons for methionine and isoleucine tRNAs differ by a single nucleotide, and changing this nucleotide in an isoleucine tRNA is sufficient to change aminoacylation specificity to methionine [25].
• The present crystal structures of the synthetase in complexes with L-isoleucine and L-valine demonstrate that the first sieve is on the aminoacylation domain containing the Rossmann fold, whereas the second, editing sieve exists on a globular beta-barrel domain that protrudes from the aminoacylation domain [10].
• The results of these experiments indicate that an unpaired guanine 2-amino group at a specific position in the minor groove of an RNA helix marks a molecule for aminoacylation with alanine [26].
• An antibody generated against a neutral phosphonate diester transition-state analog was found to catalyze the aminoacylation of the 3'-hydroxyl group of thymidine with an alanyl ester [27].
• Nalidixic acid and novobiocin inhibit the aminoacylation and pyrophosphate exchange activities of glycyl- and leucyl-transfer RNA synthetases from bakers' yeast [28].

Gene context of Aminoacylation

• Two yeast enzymes that catalyze aminoacylation of tRNAs, MetRS and GluRS, form a complex with the protein Arc1p [29].
• In accordance with this model, GCN2 bound several deacylated tRNAs with similar affinities, and aminoacylation of tRNAphe weakened its interaction with GCN2 [30].
• Surprisingly, tRNA(His) in Thg1p-depleted cells accumulates additional m(5)C modifications, which are delayed relative to the loss of G(-1) and aminoacylation [31].
• Aminoacylation activity of RRS was enhanced about 2.5-fold by the interaction with pro-EMAPII but not with its N- or C-terminal domains alone [32].
• In this study, we have examined whether variants in the leucyl tRNA synthetase gene (LARS2), involved in aminoacylation of tRNA(Leu(UUR)), associate with type 2 diabetes [33].

Analytical, diagnostic and therapeutic context of Aminoacylation

• Site-directed mutagenesis of Cys and His residues in the Zn(2+)-binding sequence reduced the aminoacylation activity; the kcat value was markedly decreased, and the Km values for L-methionine and tRNAf(Met) were increased [34].
• There was no indication of cross-reactivity by aminoacylation inhibition or, for most sera, by enzyme-linked immunosorbent assay [35].
• Immunoblotting findings and a lack of in vitro inhibition aminoacylation of tRNA(gly) by serum from this patient also suggested differences between the epitope specificity of this serum and that of other sera with anti-glycyl-tRNA synthetase antibodies [36].
• 0. In addition, valine enzyme isolated by nitrocellulose filtration during the course of an aminoacylation was shown not to be saturated with recently synthesized Val-tRNA [37].
• The effects of tRNA(Trp)variants on the aminoacylation reaction catalyzed by wild-type Escherichia coli tryptophanyl-tRNA synthe-tase (TrpRS) have now been investigated by stopped-flow fluorimetry, which allowed a pre-steady-state analysis to be undertaken [38].

References