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At least 505 records · Page 28Linked to original sources
PubMed2002

Molecular recognition of threonine tRNA by threonyl-tRNA synthetase from an extreme thermophilic archaeon, Aeropyrum pernix K1.

To investigate the recognition sites of tRNA(Thr) for threonyl-tRNA synthetase (ThrRS) from an extreme thermophilic and aerobic archaeon, Aeropyrum pernix K1, threonylation experiments using various in vitro mutant transcripts of tRNA(Thr) were examined. The results indicated that A. pernix ThrRS did recognize the first three base pairs of acceptor stem in addition to the second and the third letters of anticodon of tRNA(Thr), in spite of its N-terminal truncated unique structure. Discriminator base was not involved in recognition by A. pernix ThRS. These determinants were confirmed by the identity switching experiments from the in vitro mutants of A. pernix tRNA(Pro) and tRNA(Asn).

Archaea↗
PubMed2000

Escherichia coli proline tRNA: structure and recognition sites for prolyl-tRNA synthetase.

A major proline tRNA was purified from bulk Escherichia coli A19 tRNA by affinity chromatography with a biotinylated DNA probe. Its nucleotide sequence including modified nucleotides was determined by the post-labelling technique. In order to study the recognition sites of this proline tRNA for prolyl-tRNA synthetase, various mutant transcripts were prepared using an in vitro transcription system with T7 RNA polymerase. Based on the results of in vitro kinetic analyses of mutant transcripts, it was concluded that the second and third letters, G35 and G36, of the anticodon, G37 of the anticodon loop, the discriminator base A73, G72 of the acceptor stem, G49 and U17A that existed in the corner of an L-shaped structure are the recognition sites of proline tRNA for prolyl-tRNA synthetase.

Amino Acyl-tRNA Synthetases↗
PubMed2005

Molecular recognition of histidine tRNA by histidyl-tRNA synthetase from hyperthermophilic archaeon, Aeropyrum pernix K1.

To investigate the recognition sites of histidine tRNA for histidyl-tRNA synthetase from an extreme hyperthermophilic archaeon, Aeropyrum pernix K1, we examined histidylation activities by using overexpressed histidyl-tRNA synthetase and various histidine tRNA transcripts that were prepared by in vitro transcription system. Results indicated that anticodon was not recognized by the histidyl-tRNA synthetase similar to that of Escherichia coli histidine tRNA recognition system. Discriminator base C73 was weekly recognized and an additional G residue was specifically recognized by the enzyme.

Aeropyrum↗
PubMed1985

Inhibition of the aminoacylation of selected tRNA molecules by an estrogen-regulated factor on uterine ribosomes. Regulation of aminoacylation of tRNA by estrogens.

Administration of estradiol to ovariectomized mature rats for 1 h induces a transient increase in the peptide elongation rate on uterine ribosomes. An inhibitor of the peptide elongation rate, which appears to be regulated by estrogen treatment in vivo, can be extracted from ribosomes of estrogen-deprived rats. The extracted inhibitor or a native inhibitor-ribosome complex affects the rate of the peptide elongation reaction in a uterine cell-free protein synthesis system by inhibiting the ability of selected tRNAs in the assay to be charged with amino acids by their respective aminoacyl-tRNA synthetases. The degree of inhibition of charging of the affected tRNAs ranges from 22% to 78%, the order of inhibition being Pro greater than Val greater than Arg greater than Try greater than Leu greater than Glu greater than Ile greater than Gly greater than His greater than Ser greater than Lys. Inhibition results from a specific dose-dependent, and presumably reversible, effect of the inhibitor on tRNA, but not on the aminoacyl-tRNA synthetase. The effect does not result from removal of A-C-C terminal nucleotides from the 3' end of tRNA, but does inhibit the ability of selected tRNAs to bind to the aminoacyl-tRNA synthetases. We propose that regulation of the peptide elongation rate on uterine ribosomes by estradiol occurs through the estradiol-induced inactivation of a ribosome-associated inhibitor, which causes a reversible alteration to selected tRNAs. The modified tRNAs are unable to bind to their respective aminoacyl-tRNA synthetase to become charged with an amino acid thus causing the availability of selected aminoacyl-tRNAs to become rate-limiting in the sequential elongation of peptides.

Amino Acyl-tRNA Synthetases↗
PubMed1984

Level of rRNA, not tRNA, synthesis controls transcription of rRNA and tRNA operons in Escherichia coli.

We have recently proposed a model for the negative feedback control of rRNA and tRNA synthesis in Escherichia coli by products of rRNA operons or their derivatives (e.g., nontranslating ribosomes) (S. Jinks-Robertson, R.L. Gourse, and M. Nomura, Cell 33:865-876, 1983). In this paper, we examined the following questions. (i) Are the spacer tRNAs carried within rRNA operons the products responsible for the regulation of rRNA and tRNA transcription? (ii) Are tRNAs capable of regulating their own syntheses? We measured tRNA accumulations in cells containing plasmids with intact or defective rRNA operons or with tRNA operons. From the results obtained, we conclude that neither the tRNAs encoded within rRNA operons nor the tRNAs encoded in non-rRNA operons are capable of controlling rRNA or tRNA transcription. Therefore, the products responsible for the initial step leading to rRNA and tRNA regulation are rRNAs (or their derivatives).

Aspartate-tRNA Ligase↗
PubMed1976

Transfer RNA and aminoacyl tRNA synthetases in hormone dependent and independent mammary tumors of GR mice: II. Isoacceptor tRNA's in hormone dependent and independent mammary tumors of GR mice.

The chromatographic elution profiles of 15 aminoacyl tRNA's from dependent and independent mammary tumors of GR mice have been studied using the reversed phase chromatography (RPC 5). The seryl tRNA from the dependent tumor displayed three isoacceptor peaks while only two isoacceptor peaks were observed in the case of the independent tumor when the tRNA's were charged in the presence of the GR mice liver enzyme. Charging of the tRNA's with radioactive leucine by homologous and heterologous enzyme revealed major differences in the leucyl isoacceptor species. The homologous dependent tumor system charges five leucyl tRNA species while the independent system only charges four. The leucyl tRNA from the dependent tumor has a new peak which is only recognized by its own enzyme, but this peak is either suppressed or completely absent in the independent tumor.

Amino Acids↗
PubMedDate not supplied

[The identification of the sites of tRNA(Ser)(GCU) interaction in bovine liver with homologous aminoacyl-tRNA-synthetase by the chemical modification method].

Interaction of the bovine liver tRNA(GCUSer) having a long variable loop, with the cognate aminoacyl-tRNA synthetase has been studied by alkylation with ethylnitrosourea. It was shown that seryl-tRNA synthetase protects 3'-phosphates of nucleotides 12, 13 in D-stem and 45-47-, 47 G.-, 47 H-variable stem of tRNA(GCUreS) from alkylation. An anticodon loop of tRNA(GCUSer) did not interact with seryl-tRNA synthetase.

Alkylation↗
PubMed1990

[Determination of interacting segments of tRNA(Leu) from cow mammary glands with homologous aminoacyl-tRNA-synthetase by a chemical modification method].

The interaction of the cow mammary gland tRNA(IAGLeu), having a long variable loop, with the cognate aminoacyl-tRNA synthetase has been studied by the alkylation with ethylnitrosourea. It was shown that leucyl-tRNA synthetase protects from alkylation 3'-phosphates of the nucleotides 12-13 in D-loop, 23-24 in D-stem and 37-43 in the anticodon arm of tRNA(IAGLeu). All regions of interaction with the aminoacyl-tRNA synthetase are located in the same plane of tRNA whereas the long variable loop is in another plane.

Alkylation↗
PubMedDate not supplied

[Tyrosine tRNA(Q*psiA) from bovine liver. Identification of its sites of interaction with homologous aminoacyl-trna synthetase using chemical modification].

Interaction of the bovine liver tyrosine tRNA Q*psi A having short variable loop, with the homologous aminoacyl-tRNA synthetase has been studied by alkylation with ethylnitrosourea. It is shown that tyrosyl-tRNA synthetase (form M.r. 2x39000) protects 3'-phosphates of nucleotides 21 in D-loop, 31 and 44 in anticodon stem and 59-64 T psi C-stem of tRNA Tyr from alkylation. An anticodon of tRNA Tyr did not interact with this proteolytically modified form of tyrosyl-tRNA synthetase (M.r. 2x39000).

Amino Acyl-tRNA Synthetases↗
PubMed1986

Threonyl-tRNA synthetase gene maps close to leucyl-tRNA synthetase gene on human chromosome 5.

The structural gene for threonyl-tRNA synthetase was mapped to human chromosome 5 by an analysis of the isoelectric focusing patterns of this enzyme from human X Chinese hamster interspecific somatic cell hybrids. The threonyl-tRNA synthetase gene is the fourth of seven aminoacyl-tRNA synthetase genes mapped in humans to be assigned to this chromosome. Regional mapping studies showed that the threonyl-tRNA synthetase gene is on the short arm of chromosome 5, p13-cen, and is close to, but separable from, the gene for leucyl-tRNA synthetase which maps to 5cen-5q11.

Amino Acyl-tRNA Synthetases↗
PubMedDate not supplied

Phosphorylation of glutaminyl-tRNA synthetase and threonyl-tRNA synthetase by the gene products of dnaK and dnaJ in Escherichia coli K-12 cells.

In Escherichia coli K-12, the heat shock protein DnaK and DnaJ participate in phosphorylation of both glutaminyl-tRNA synthetase and threonyl-tRNA synthetase since when cellular proteins extracted from the dnaK7(Ts), dnaK756(Ts) and dnaJ259(Ts) mutant cells labeled with 32Pi at 42 degrees C were analyzed by two-dimensional gel electrophoresis, no phosphorylation of glutaminyl-tRNA synthetase and threonyl-tRNA synthetase was observed while phosphorylation of both aminoacyl-tRNA synthetases was detected in the samples extracted from wild-type cells.

Amino Acyl-tRNA Synthetases↗
PubMed1990

Affinity labeling of aminoacyl-tRNA synthetases with adenosine triphosphopyridoxal: probing the Lys-Met-Ser-Lys-Ser signature sequence as the ATP-binding site in Escherichia coli methionyl-and valyl-tRNA synthetases.

Pyridoxal 5'-triphospho-5'-adenosine (AP3-PL), the affinity labeling reagent specific for lysine residues in the nucleotide-binding site of several enzymes [Tagaya, M., & Fukui, T. (1986) Biochemistry 25, 2958-2964; Yagami, T., Tagaya, M., & Fukui, T. (1988) FEBS Lett. 229, 261-264], was used to identify the ATP-binding site of Escherichia coli methionyl-tRNA synthetase (MetRS). Incubation of this enzyme with AP3-PL followed by reduction with sodium borohydride resulted in a rapid inactivation of both the tRNA(Met) aminoacylation and the methionine-dependent ATP-PPi exchange activities. Complete inactivation corresponded to the incorporation of 0.98 mol of AP3-PL/mol of monomeric trypsin-modified MetRS. ATP or MgATP protected the enzyme from inactivation. The labeling with AP3-PL was also applied to E. coli valyl-tRNA synthetase (ValRS). Both the tRNA(Val) aminoacylation and the valine-dependent ATP-PPi exchange activities were abolished by the incorporation of 0.91 mol of AP3-PL/mol of monomeric ValRS. AP3-PL was found attached to lysine residues 335, 402, and 528 in the primary structure of MetRS. In the case of ValRS, the AP3-PL-labeled residues corresponded to lysines 557, 593, and 909. We therefore conclude that these lysines of MetRS and ValRS are directed toward the ATP-binding site of these synthetases, more specifically at or close to the subsite for the gamma-phosphate of ATP. AP3-PL-labeled Lys-335 of MetRS and Lys-557 of ValRS belong to the consensus tRNA CCA-binding Lys-Met-Ser-Lys-Ser sequence [Hountondji, C., Dessen, P., & Blanquet, S. (1986) Biochimie 68, 1071-1078].(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1998

Human asparaginyl-tRNA synthetase: molecular cloning and the inference of the evolutionary history of Asx-tRNA synthetase family.

We have cloned and sequenced a cDNA encoding human cytoplasmic asparaginyl-tRNA synthetase (AsnRS). The N-terminal appended domain of 112 amino acid represents the signature sequence for the eukaryotic AsnRS and is absent from archaebacterial or eubacterial enzymes. The canonical ortholog for AsnRS is absent from most archaebacterial and some eubacterial genomes, indicating that in those organisms, formation of asparaginyl-tRNA is independent of the enzyme. The high degree of sequence conservation among asparaginyl- and aspartyl-tRNA synthetases (AsxRS) made it possible to infer the evolutionary paths of the two enzymes. The data show the neighbor relationship between AsnRS and eubacterial aspartyl-tRNA synthetase, and support the occurrence of AsnRS early in the course of evolution, which is in contrast to the proposed late occurrence of glutaminyl-tRNA synthetase.

Amino Acid Sequence↗