Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q96FX7 (tRNA)
 26,753 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The procedure for isolating aminoacyl-tRNA-synthetases from yeast Candida utilis IBPM-405 was developed. The rate of activation of L-amino acids in the formation of hydroxamates was different. Aspartic acid, asparagine, glutamic acid, tryptophane, phenyl alanine and methionine underwent the highest activation. The activation of alanine, arginine, hydroxyproline, serine and isoleucine was insignificant. Using aspartic acid, it was shown that the hydroxamate formation was ATP-stimulated and that the amount of hydroxamate increased with a rise of the protein concentration in the mixture to 9-10 mg/ml. The hydroxamate formation was inhibited by p-chloromercury-benzoate and heavy metal ions. Yeast aminoacyl-tRNA-synthetases showed L-aspartic and L-glutamic activities that were independent from Mg++ ions and ATP.
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PMID:[Activation of L-amino acids by aminoacyl-tRNA-synthetases from yeast Candida utilis IBPM-405]. 0 29

Treatment of Escherichia coli formylmethionine tRNA with 2 M sodium bisulfite, pH 7.0, in 10 mM MgCl2 at 25 degrees results in formation of uridine/bisulfite adducts at U18 in the dihydrouridine loop, U37 in the anticodon, and U48 in the variable loop. Two products, corresponding to the two diastereoisomers of 5,6-dihydrouridine-6-sulfonate, are formed at each reactive site in the tRNA. Although none of the modifications cause complete loss of methionine acceptor activity, the modified tRNA is amino-acylated at a reduced rate and has a decreased affinity for E. coli methionyl-tRNA synthetase. Aminoacylation of [35S]bisulfite-labeled tRNAfMet with a limiting amount of purified enzyme followed by separation of the acylated and unacylated molecules and structural analysis has shown that the presence of a specific diastereoisomer of the uridine/bisulfite adduct in the anticodon base U37 alters the kinetic parameters for aminoacylation of tRNAfMet.
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PMID:Alteration of the kinetic parameters for aminoacylation of Escherichia coli formylmethionine transfer RNA by modification of an anticodon base. 1 33

Cysteinyl- and methionyl-tRNA synthetases (EC 6.11.-) were purified 1200- and 1000-fold, respectively, from sonic extracts of Paracoccus denitrificans strain 8944, and kinetics, substrate specificity and regulatory properties were determined using the ATP-PPi exchange reaction. Both enzymes had pH optima of approx. 8 and were inhibited by sulphydryl-group reagents. Cysteinyl-tRNA synthetase catalysed L-selenocysteine- and alpha-aminobutyric acid-dependent ATP-PPi exchange and methionyl-tRNA synthetase catalysed L-homocysteine-, L-selenomethionine- and norleucine-dependent ATP-PPi exchange. Both enzymes were inhibited by O-acetylserine. Cysteinyl-tRNA synthetase activity was stimulated by methionine and methionyl-tRNA synthetase activity was stimulated by sulphide, cysteine, and cysteic acid.
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PMID:Sulphur metabolism in Paracoccus denitrificans. Purification, properties and regulation of cysteinyl-and methionyl-tRNA synthetase. 1 93

After T4 bacteriophage infects Escherichia coli, a peptide tau, produced under the control of a phage gene, binds to the host valyl transfer ribonucleic acid synthetase (EC 6.1.1.9) and thereby changes several of its physicochemical properties. The interaction of tau with the host enzyme was investigated in vitro after extensively purifying the factor from T4-infected E. coli using a rapid purification procedure. The tau preparation migrated as a single, protein-staining band with a molecular weight of 11,000 during sodium dodecyl sulfate-gel electrophoresis. The purified peptide completely converted partially purified valyl-tRNA synthetase from uninfected E. coli into the form present in cell-free extracts prepared from virus-infected bacteria. The enzyme modified in vitro also exhibited the enhanced affinity for tRNA characteristic of the viral form of valyl-tRNA synthetase. The addition of bulk tRNA from E. coli B, tRNAVal, or tRNA1Val to enzyme modified in vitro increased its sedimentation rate to that of enzyme prepared from phage-infected cells. Amino acid analysis of the purified tau peptide revealed a relatively high concentration of the amino acids lysine and alanine, and a lack of detectable proline, tyrosine, phenylalanine, and methionine.
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PMID:Purification and properties of a T4 bacteriophage factor that modifies valyl-tRNA synthetase of Escherichia coli. 1 75

The influence of buffer, pH, Mg2+, ATP, Na+, K+ and temperature on the extent and rate of aminoacyl-tRNA synthesis was studied with the shark Mustelus mento liver tRNAs and aminoacyl-tRNA synthetases. The optimum pH for the aminoacylation of tRNAMet was 8.3 and for tRNAVal 7.0. For these two tRNAs the Mg2+ optimum was related to the levels of ATP required and to the pH of the reactions. It is suggested that the Mg2+ concentration required for each aminoacylation system reflects the true conditions under which the substrate for the enzyme, the MgATP2- complex, is formed. The effect of monovalent cations was also examined. Val-tRNA synthesis was slightly stimulated up to a concentration of 50 mM NaCl (KCl). Over 100 mM salt, a rapid inhibition was observed. Met-tRNA synthesis behaves differently by being stimulated over a wide range of salt concentrations.
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PMID:Studies on fish liver protein synthesis. II. Factors influencing the aminoacylation of shark liver transfer ribonucleic acid. 1 27

Kinetic studies have been performed on the "family" of aminoacyl synthetases from calf liver. All assays were based on the esterification of amino acids to tRNA. Optimized reaction conditions for each synthetase are reported. Most of the synthetases show hyperbolic kinetics with respect to both amino acid and tRNA concentration, however a few show sigmoidal kinetics with respect to one substrate. Arginine, methionine and proline synthetases show sigmoidal kinetics with respect to mixed tRNA solutions and have Hill coefficients of 1.30, 1.10 and 1.20 respectively. Alanine and isoleucine synthetases show sigmoidal kinetics with respect to amino acid concentration and have Hill coefficients of 1.21 and 1.40 respectively.
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PMID:Aminoacyl-tRNA synthetases from calf liver: optimized assay conditions and kinetic properties. 2 May 69

Biotin deficiency in Aspergillus nidulans resulted in a 70% increase of the protein content and increased levels of free and bound aspartate, glutamate, serine, leucine and methionine. Likewise, the activities of NADP+ glutamate dehydrogenase, NAD+ gluatmate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were significantly increased. The total RNA content increased while the DNA content was unaffected. The rRNA/tRNA ratio remained higher in biotin-deficient cells. Supplementation of glutamate, aspartate, serine, leucine and methionine to the culture medium raised the rRNA/tRNA ratio, and the difference observed in the qualitative and the quantitative patterns of protein and dry cell mass between normal and biotin-deficient cultures was abolished.
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PMID:Factors affecting protein synthesis during biotin deficiency in Aspergillus nidulans. 4 77

E. coli C6 rel- met- cys- was cultured in a fully supplemented medium and in media lacking cysteine or methionine. tRNA isolated from the three cultures containted, respectively, a normal complement of modified nucleosides; a deficiency in thiolated nucleosides and a deficiency in methylated nucleosides. Both sulfur-deficient tRNA and methyl-deficient tRNA contained large amounts of N-6- (delta-2-isopentenyl) adenosine and small amounts of the 2-methylthio derivative. Methyl-deficient tRNA contained, in addition a large amount of a cytokinin active, differently modified nucleoside that is believed to be a sulfur derivative of N6-(delta-2-isopentenyl) adenosine. The structure of this compound is unknown. When methly-deficient tRNA and the precusor the tRNA-Tyr su3-+ A25 were enzymatically methylated in vitro, methyl groups were incorporated into derivatives of isopentenyladenosine. These results indicate that the biosynthesis of the 2-methylthio derivative of isopentenyladenosine may occur in a sequential manner, i.e., thiolation of isopentenyladenosine followed by methylation.
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PMID:Maturation of a hypermodified nucleoside in transfer RNA. 4 80

RNA-directed DNA synthesis by detergent-disrupted virions of Rous sarcoma virus (RSV) initiates by the covalent attachment of pdA to the 3'-terminal rA of a 4S RNA hydrogen-bonded to the 70S RNA template. This 4S "primer" has structural features of tRNA and can be aminoacylated with methionine. Synthesis and integration of provirus DNA can be monitored in both permissive (duck) and nonpermissive (mouse) cells acutely infected with RSV. The results of these studies, as well as data obtained with RSV-infected mammalian cells which have reverted from a transformed to a pheno-typically normal state, indicate that integration of viral genes into the host chromosome is not sufficient cause for transformation. Pertinent features of virus-specific RNA-directed DNA synthesis in vitro and in vivo are reviewed and compared.
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PMID:Transcription of the Rous sarcoma virus genome in vitro and in vivo. 5 35

As previously reported (G. H. Jones, 1975), transfer ribonucleic acids (tRNA's) and ribosomes from actinomycin-producing cultures of Streptomyces antibioticus show a decreased ability to function in aminoacylation and translation as compared with the corresponding components from younger cells. Further, specific changes in the isoacceptor patterns are revealed when tRNA's from actinomycin-producing cells are compared with those of younger cells by reverse- phase column chromatography. A specific glycyl-tRNA species is eliminated from the reverse-phase profile of tRNA's from actinomycin-producing S. antibioticus cells as compared with younger cells. Changes in isoacceptor patterns were also observed for the amino acids methionine, valine, phenylalanine, and leucine. Actinomycin synthesis was inhibited by growing S. antibioticus cells in the presence of alpha-methyl-DL-tryptophan. Inhibition of actinomycin synthesis reversed the changes in tRNA observed in normally grown control cultures, although it had no demonstrable effect on the growth of the cells. Thus, tRNA from 48-h-old, alpha-methyl-tryptophan-grown cells had amino acid acceptor activity that was equal to or greater than that of tRNA from 12-h-old, normally grown cells. Similarly, the reverse-phase chromatographic pattern for glycyl-tRNA's from 48-h-old, alpha-methyl-tryptophan-grown cells was identical to that of the glycyl-tRNA's from 12-h-old, normally grown cells. In contrast, the ability of ribosomes from 48-h-old, alpha-methyl-tryptophan-grown cells to function in polypeptide synthesis in vitro was essentially identical to that of 48-h-old, normally grown cells. Ribosomes from 12-h-old, normally grown cells were severalfold more active in in vitro polypeptide synthesis.
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PMID:Relationship between changes in the translational apparatus and actinomycin production in Streptomyces antibioticus. 6 58


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