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PubMedDate not supplied

[Features of the structure of transfer RNA coded by bacteriophage T5].

Nucleotide sequence of 24 genes for the bacteriophage T5 tRNAs specific for all amino acids involved in protein synthesis was determined. All of them, except tRNA(Pro), were shown to differ significantly from the generalized "clover-leaf" structure consisting in the displacement of invariant and semi-invariant residues, the absence of pairing in the stems and some other deviations from the canonical parameters of the model. Basing on the available information on the functional activity of the phage-specific tRNAs, one can put forward a suggestion that, at least for some of them, the above anomalies do not essentially influence their activity. A comparison of phage T5 tRNAs with the Escherichia coli and phage T4 counterparts was carried out. The majority of the known elements determining the specificity of E. coli tRNA aminoacylation was also found in all phage T5 tRNAs, except tRNAPhe).

Base Sequence↗
PubMed1969

Transfer RNA: A comparison by gel electrophoresis of the tRNA in HeLa cytoplasm, HeLa mitochondrial fraction, and E. coli.

A class of transfer RNA separable from the majority of transfer RNA by gel electrophoresis has been observed in E. coli and in the mitochondrial fraction of HeLa cells but not in HeLa cytoplasm. The size of this class of transfer RNA, as judged by its mobility on polyacrylamide gel, is intermediate between the major part of the transfer RNA and 5S RNA. It exists in part associated with the ribosomes, and its amino acid acceptor activity is different from the major class of transfer RNA.

Cytoplasm↗
PubMed1982

Translational efficiency of transfer RNA's: uses of an extended anticodon.

Transfer RNA's are probably very strongly selected for translational efficiency. In this article, the argument is presented that the coding performance of the triplet anticodon is enhanced by selection of a matching anticodon loop and stem sequence. the anticodon plus these nearby sequence features (the extended anticodon) therefore contains more coding information than the anticodon alone and can perform more efficiently and accurately at the ribosome. This idea successfully accounts for the relative efficiencies of many transfer RNA's.

Base Sequence↗
PubMed1971

Cross-linked transfer RNA functions in all steps of the translation process.

A specific photochemical reaction between 4-thiouridine and cytosine cross-links two arms of transfer RNA. This cross-link, introduced into phenylalanine transfer RNA and arginine transfer RNA, limits the conformational freedom of the molecule. Both modified transfer RNA's are capable of functioning in all steps of protein synthesis with this restraint on allowable conformations.

Arginine↗
PubMed1989

Intermediate states in the movement of transfer RNA in the ribosome.

Direct chemical 'footprinting' shows that translocation of transfer RNA occurs in two discrete steps. During the first step, which occurs spontaneously after the formation of the peptide bond, the acceptor end of tRNA moves relative to the large ribosomal subunit resulting in 'hybrid states' of binding. During the second step, which is promoted by elongation factor EF-G, the anticodon end of tRNA, along with the messenger RNA, moves relative to the small ribosomal subunit.

Binding Sites↗
PubMed1976

Control of transfer RNA synthesis in the presence of inhibitors of protein synthesis.

The rate of synthesis of transfer RNA in suspension cultures of Chang's liver cells, has been examined in the presence of various inhibitors of protein synthesis with different modes of action. Inhibitors of polypeptide chain elongation such as cycloheximide and emetine stimulated the rate of synthesis of transfer RNA at concentrations that inhibited protein synthesis by 60-90%. Trichodermin, an inhibitor of the elongation and termination steps in protein synthesis, had as effect similar to that of cycloheximide and emetine. On the other hand verrucarin, an inhibitor of initiation, and puromycin, an analogue of the aminoacyl terminus of tRNA, had little effect of the synthesis of transfer RNA at low concentrations. At high concentrations these compounds inhibited transfer RNA synthesis. Inhibitors of protein synthesis can be divided in two groups based on their effect on the polysom pattern. The first group increased the number of large polysomes, while verrucarin and puromycin lead to a break down of large polysomes and to an accumulation of monosomes and small polysomes. Thus, there appears to be a correlation between the effect of these inhibitors of protein synthesis on the aggregational state of the polysomes and their effect on the rate of transfer RNA synthesis.

Anti-Bacterial Agents↗
PubMed1988

A simple structural feature is a major determinant of the identity of a transfer RNA.

Analysis of a series of mutants of an Escherichia coli alanine transfer RNA shows that substitution of a single G-U base pair in the acceptor helix eliminates aminoacylation with alanine in vivo and in vitro. Introduction of that base pair into the analogous position of a cysteine and a phenylalanine transfer RNA confers upon each the ability to be aminoacylated with alanine. Thus, as little as a single base pair can direct an amino acid to a specific transfer RNA.

Base Composition↗
PubMed2005

Transfer RNA gene recruitment in mitochondrial DNA.

Transfer RNA (tRNA) is the adaptor molecule that mediates recognition of the codon sequence in mRNA and enables its translation into the appropriate amino acid. Accordingly, phylogenetic relationships among tRNA genes are often thought to recapitulate the evolution of the genetic code. However, it has been demonstrated experimentally that one tRNA gene can be replaced with a copy of another carrying a single mutation in its anticodon sequence. In this article, we show that such "gene recruitment" has occurred recently and repeatedly in the mitochondrial genome of the demosponge Axinella corrugata and appears to be a common phenomenon in the evolution of the tRNA multigene family.

Animals↗
PubMed1971

Purification and in vitro transcription of a transfer RNA gene.

A gene specifying tyrosine transfer RNA has been purified and transcribed in vitro. The purification procedure made use of two specialized transducing phages carrying the tRNA(Tyr) gene of Escherichia coli inserted into their DNA in opposite orientations. The separated heavy strands of the two phages were annealed and the single-stranded tails of the resulting hybrid were removed by digestion with Neurospora endonuclease. The size of the purified double-stranded structures was determined by electron microscopy. These isolated duplexes served as template for the in vitro transcription of tRNA(Tyr)-like molecules.

Centrifugation, Density Gradient↗
PubMed1977

In vivo repair of the 3'terminus of transfer RNA injected into amphibian oocytes.

Yeast transfer RNA specific for phenylalanine has been treated chemically to remove either one or two nucleotides of its 3' terminus and has been injected into Xenopus laevis oocytes to test whether this RNA can be repaired in vivo. The results obtained showed that oocytes could aminoacylate and thus repair tRNAPhe that has lost both its terminal adenosine and 3' phosphate. A similar result was obtained with tRNAPhe that had undergone two full cycles of 3' terminal nucleotide removal. The oocytes cannot aminoacylate tRNAPhe whose 3' terminal ribose has been oxidized with periodate or the derivative that retains a 3' phosphate after adenosine removal. In vitro assays show that the Xenopus ovary contains a tRNA nucleotidyl transferase with the properties similar to enzymes obtained from other sources which may be responsible for the 3' terminal repair observed in vitro.

Animals↗
PubMed1971

Raman spectrum of a transfer RNA.

Raman spectrum of purified formylmethionine transfer RNA from Escherichia coli has been observed in its aqueous solution. In the 1800 to 200 cm(-l) range, about 30 Raman lines are found, each of which can be assigned to one of the constituent nucleotide residues. From the positions and intensities of the lines, information on the intramolecular environments of these base residues can be obtained.

Adenine Nucleotides↗
PubMed1984

Phenylalanine transfer RNA: molecular dynamics simulation.

Yeast phenylalanine transfer RNA was subjected to a 12-picosecond molecular dynamics simulation. The principal features of the x-ray crystallographic analysis are reproduced, and the amplitudes of atomic displacements appear to be determined by the degree of exposure of the atoms. An analysis of the hydrogen bonds shows a correlation between the average length of a bond and the fluctuation in that length and reveals a rocking motion of bases in Watson-Crick guanine X cytosine base pairs. The in-plane motions of the bases are generally of larger amplitude than the out-of-plane motions, and there are correlations in the motions of adjacent bases.

Chemical Phenomena↗
PubMedDate not supplied

Evolution of the transfer RNA molecule.

Base sequences of many transfer RNA (tRNA) species obtained from different sources contain homologous regions. These homologies, which are 6 to 20 nucleotides long, occur both within the same tRNA molecule and between many different tRNA molecules repeatedly. Since it is very unlikely an 80 or so nucleotide long tRNA molecule could have been formed at once, under primordial conditions, we propose that the homologous oligonucleotides found within the tRNA molecules to-day represent the earliest adapter from which tRNA molecules have evolved.

Base Sequence↗