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At least 91 records · Page 5Linked to original sources
PubMed2001

Transfer RNA(Ala) recognizes transfer-messenger RNA with specificity; a functional complex prior to entering the ribosome?

tmRNA (SsrA or 10Sa RNA) functions as both a transfer RNA and a messenger RNA, rescues stalled ribosomes and clears the cell of incomplete polypeptides. We report that native Escherichia coli tmRNA interacts specifically with native or synthetic E.coli tRNA alanine (tRNA(Ala)) in vitro, alanine being the first codon of the tmRNA internal open reading frame. Aminoacylatable RNA microhelices also bind tmRNA. Complex formation was monitored by gel retardation assays combined with structural probes. Nucleotides from the acceptor stem of tRNA(Ala) are essential for complex formation with tmRNA. tRNA(Ala) isoacceptors recognize tmRNA with different affinities, with an important contribution from tRNA(Ala) post-transcriptional modifications. The most abundant tRNA(Ala) isoacceptor in vivo binds tmRNA with the highest affinity. A complex between tRNA(Ala) and tmRNA might involve up to 140 tmRNA molecules out of 500 present per E.coli cell. Our data suggest that tmRNA interacts with the tRNA that decodes the resume codon prior to entering the ribosome. Biological implications of promoting specific complexes between tmRNA and aminoacylatable RNAs are discussed, with emphasis on primitive versions of the translation apparatus.

Base Sequence↗
PubMed1978

Photobinding of 8-methoxypsoralen to transfer RNA and 5-fluorouracil-enriched transfer RNA.

The photobinding of [3H]8MOP to tRNA upon irradiation at 365 nm in the absence of O2 was determined by gel filtration. The maximum photobinding was found to be ca. 4 mol of 8MOP er mol of tRNA and 5FU-tRNA, with an overall quantum yield of 2.3 X 10(-3). The photobinding kinetics for 8MOP-tRNA showed an apparent induction period or sigmoidal kinetic curve, indicating a specific initial photobinding site on tRNA which was identified as 4-thiouridine at position 8 from the 5'-end of Escherichia coli tRNA. Photobinding of 8MOP to 5FU-tRNA proceeded without an apparent induction period. 8MOP-tRNA and 8MOP-5FU-tRNA adducts were characterized by absorption, fluorescence, and CD spectroscopy. A modified procedure was also developed to analyze the nucleoside composition in modified 8MOP-tRNA and 8MOP-5FU-tRNA. The results showed that 8MOP photochemically added mainly to pyrimidine bases. The photobinding of 8MOP changed the conformation (secondary in particular) of tRNA and inhibited aminoacyl-tRNA synthetase activity.

Amino Acyl-tRNA Synthetases↗
PubMed1982

Computer program for storage and retrieval of the nucleic acid structures: storing and updating of transfer RNA sequences - drawing of the secondary structure for transfer RNA by computer.

The availability of a large number of tRNA sequences has created a need for computer programs to store the data. A program written in FORTRAN language allows one to store tRNA sequences and to retrieve information. The data are stored in such a way that it allows a direct comparison of various tRNA sequences. Moreover, the program draws the 'cloverleaf' structure of any stored tRNA sequence and also provides the characteristics of minor, modified nucleosides and major references. Additions and corrections to the program and stored data can be made easily and an individual does not need computer programming skills to use the program.

Base Sequence↗
PubMed1976

Biosynthesis of mammalian transfer RNA. Evidence for regulation by deacylated transfer RNA.

The rate of tRNA synthesis in cultured Friend leukemia cells has been examined as a function of the variation in polyribosome structure produced by treatment with a variety of inhibitors of protein synthesis. The results indicate, in contrast to the conclusions of Bölcsföldi (Bölcsföldi, G. (1974) Exp. Cell Res., 88, 231--240), that no necessary relationship exists between the ribosome distribution and the rate of tRNA synthesis. Alternatively, it is observed that inhibitors of tRNA aminoacylation cause, in all cases, a decrease in the rate of tRNA synthesis whereas drugs which may stimulate the aminoacylation of tRNA cause, in all cases, an elevation of the rate of tRNA synthesis. It is concluded that tRNA synthesis in mammalian cells may be regulated by the relative levels of acylated and deacylated tRNA.

Animals↗
PubMed1979

Isolation of the transfer RNA genes of bacteriophage T4 and transfer RNA synthesis in vitro.

Non-glucosylated T4 DNA was restricted with the endonuclease EcoRI and the mixture of DNA fragments separated by gel electrophoresis and transcribed with purified Escherichia coli RNA polymerase. Three purified fragments were shown to act as templates for tRNA synthesis. A smaller fragment, shown to be hybridizable to 32P-labeled T4 tRNA was not transcribable. It was concluded that the promoter for T4 tRNA synthesis had been separated from the structural genes in the smaller fragment by EcoRI and that the distal portion of the tRNA gene cluster lacks internal promoters which display in vitro activity. Preparations of non-glucosylated T4 DNA were never fully restricted with EcoRI and when the larger purified fragments carrying the tRNA were restricted with excess enzyme only a slight cleavage to yield the smaller fragments was obtained. The property of the DNA-limiting complete restriction is not know.

Cell-Free System↗
PubMed1978

Nucleotide sequence of phenylalanine transfer RNA from Schizosaccharomyces pombe: implications for transfer RNA recognition by yeast phenylalanyl-tRNA synthetase.

The nucleotide sequence of Schizosaccharomyces pombe tRNAPhe was determined to be pG-U-C-G-C-A-A-U-G**-G*-U-G-psi-A-G-D-D-G-G-G-A-G-C-A-psi-G*-A-C-A-G-A-Cm-U-Gm-A-A-Y-A-psi-m5C-U-G-U-U-G-m7G-U*-C-A-U-C-G-G-T-psi-C-G-A-U-C-C-C-G-G-U-U-U-G-U-G-A-C-A-C-C-AOH. This sequence differs from that of S. cerevisiae tRNAPhe in 27 nucleotides. Saccharomyces cerevisiae phenylalanyl-tRNA synthetase aminoacylates both the homologous tRNAPhe and S. pombe t-NAPhe; the reactions have similar Km and Vmax values. However, the nucleotide sequence in the D stem is different in the two tRNAs. This region was proposed by Roe, B., et al. [(1973) Biochemistry 12, 4146--4154] to be the major recognition site for yeast phenylalanyl-tRNA synthetase, but the present results cast doubt on the validity of this hypothesis.

Amino Acyl-tRNA Synthetases↗
PubMed1976

The biosynthesis of transfer RNA in insects. II. Isolation of transfer RNA precursors from the posterior silk gland of Bombyx mori.

The occurrence of precursors to tRNA in the post-polysomal fraction of the posterior silk gland of Bombyx mori was demonstrated by pulse-chase labeling and DNA-RNA hybridization competition experiments. These precursors had molecular sizes ranging from 4S to 5S on polyacrylamide gel electrophoresis. Analysis of the incorporation of the methyl group from [methyl-14C]methionine revealed that a radioactive peak on polyacrylamide gel appeared in the 4.5S region during brief labeling. This suggested that some methylation occurred at the 4.5S precursor step.

Bombyx↗
PubMed1982

Euglena gracilis chloroplast transfer RNA transcription units. I. Physical map of the transfer RNA gene loci.

The locations of transfer RNA genes with respect to the restriction endonuclease cleavage map of Euglena gracilis Klebs, strain Z Pringsheim chloroplast DNA have been determined. Purified chloroplast tRNAs were treated with snake venom phosphodiesterase to remove the 3'-CCA terminus, and radioactively labeled by the action of Escherichia coli tRNA nucleotidyltransferase in the presence of [alpha-32P]CTP. Chloroplast DNA was treated individually and with combinations of the enzymes Bal I, Bam HI, Eco RI, Pst I, Pvu II, Sal I, and Xho I. The location of tRNA genes with respect to the cleavage sites for these enzymes was determined by hybridization of the 32P-labeled tRNAs to membrane filter blots of the chloroplast DNA restriction nuclease fragments following gel electrophoresis. The 145-kilobase pair genome was resolved into nine areas of strong tRNA hybridization, separated by areas of weak or no tRNA hybridization. The loci of tRNA genes are within the Eco RI fragments Eco A, B, G, H, I, J', P, Q, and V.

Base Sequence↗