PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “RNA, Transfer”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed1983

Euglena gracilis chloroplast transfer RNA transcription units. Nucleotide sequence analysis of a tRNAThr-tRNAGly-tRNAMet-tRNASer-tRNAGln gene cluster.

The arrangement and the nucleotide sequence of the tRNA genes in the 2.0-kilobase-pair EcoRI restriction fragment EcoQ of Euglena gracilis Klebs, strain Z Pringsheim chloroplast DNA have been determined. This fragment, cloned in pBR325 to form the plasmid pEZC300, contains five tRNA genes. The DNA insert of this plasmid, a known tRNA gene locus (Orozco, E.M., Jr., and Hallick, R.B. (1982) J. Biol. Chem. 257, 3258-3264) has been mapped by Southern gel analysis using a 32P-labeled oligodeoxynucleotide tRNA gene probe. The DNA sequence of 870 base pairs (bp) from EcoQ containing the entire tRNA gene locus was determined. The organization of this tRNA gene cluster on the E. gracilis chloroplast chromosome is tRNAUUGGln-14-BP spacer-RNAGCUSer-175-bp spacer-tRNACAUMet-12-bp spacer-tRNAGCCGly-5-bp spacer-tRNAUGUThr. The tRNAUUGGln and tRNAGCUSer gene sequences are of the opposite polarity as the other three gene sequences, but of the same polarity as the rRNA genes. The tRNAMet gene is a putative initiator tRNA. The five tRNA genes are separated and flanked by A-T-rich spacer sequences. This gene arrangement is consistent with the model that E. gracilis chloroplast tRNA genes are transcribed into multicistronic tRNA precursors. The DNA sequences have been used to deduce the primary and secondary structures of the tRNAs.

Animals↗
PubMed1983

Transfer RNA pyrophosphorolysis with CTP(ATP):tRNA nucleotidyltransferase. A direct route to tRNAs modified at the 3' terminus.

The pyrophosphorolysis of tRNA by yeast CTP-(ATP):tRNA nucleotidyltransferase has been studied in an effort to define the behavior of the enzyme and the experimental parameters that lead to net loss of the 3'-terminal nucleotide or to nucleotide exchange. It was found that removal of AMP from the terminus of tRNA proceeded optimally at 1.0 mM PPi; incorporation of 2'- or 3'-dAMP was also studied and shown to proceed optimally at a 6.0 mM concentration of deoxynucleoside triphosphate. CTP was shown to inhibit the pyrophosphorolysis and nucleotide exchange observed when starting from intact tRNA, but apparently not by inhibiting removal of CMP from tRNA missing the 3'-terminal adenosine moiety. The optimized conditions for nucleotide exchange were used for the preparative conversion of tRNAs to species terminating in 2'- and 3'-deoxyadenosine.

Kinetics↗
PubMed1983

A change in isoaccepting leucine transfer RNA species in rat brain after prolonged ingestion of ethanol.

The effects of prolonged ethanol administration (10% ethanol-water solution as the sole drinking fluid for 6 to 14 weeks) on brain ribosomes and tRNA were studied in Sprague-Dawley rats. For comparison, liver ribosomes were also studied. The amounts of ribosomes in brain and liver and the proportion of the ribosomes in the form of polyribosomes were found to be essentially unaltered after 14 weeks of ethanol intake. In the brains of ethanol-treated animals, the total amount of unfractionated tRNA was slightly increased after 6 weeks. The acceptance of radioactive glutamic acid, leucine, methionine, phenylalanine, proline and serine by tRNA was also unaltered. When the activities of aminoacyl-tRNA synthetases specific for the six amino acids were studied in cross-over experiments, no changes were found. Comparison of the isoaccepting species of [14C]Met-, [14C]Leu- and [14C]Ser-tRNA by chromatography on benzoylated DEAE-cellulose revealed significant alteration in the chromatographic profile of [14C]Leu-tRNA derived from the brains of the alcohol-treated rats. These results suggest that prolonged intake of relatively small amounts of ethanol is accompanied in rats by essentially no alterations in total amounts of brain and liver ribosomes, brain tRNA, or activities of several aminoacyl-tRNA synthetases. As demonstrated by the leucine tRNAs, however, the quantitative distribution of isoaccepting tRNA species may change.

Alcoholism↗
PubMed1980

Bacteriophage T5 transfer RNA. Isolation and characterization of tRNA species and refinement of the tRNA gene map.

Previous studies from this laboratory have provided a high resolution map for 16 tRNA genes located on the continuous heavy DNA strand of bacteriophage T5 DNA (Chen, M.-J., Locker, J., and Weiss, S.B. (1976) J. Biol. Chem. 251, 536-547). All of the T5 tRNA genes were located in three clusters within the DNA C segment, except for tRNAArg, which mapped on the left end of the DNA D segment (Desai, S.M., Hunt, C., Locker, J., and Weiss, S.B. (1978) J. Biol. Chem. 253, 6544-6550). In this report, we present evidence for the presence of eight additional T5 tRNA species, five of which are located in two new loci within the DNA C segment. We also describe a two-dimensional gel electrophoresis system for the separation and isolation of T5 tRNA species from crude infected RNA preparations. The gel electrophoresis system separates tRNA isoacceptors specific for different amino acids; evidence is presented that the isoacceptors for isoleucine, histidine, and serine are coded by different T5 genes.

Base Sequence↗
PubMed1996

Transfer RNA structural change is a key element in the reassignment of the CUG codon in Candida albicans.

The human pathogenic yeast Candida albicans and a number of other Candida species translate the standard leucine CUG codon as serine. This is the latest addition to an increasing number of alterations to the standard genetic code which invalidate the theory that the code is frozen and universal. The unexpected finding that some organisms evolved alternative genetic codes raises two important questions: how have these alternative codes evolved and what evolutionary advantages could they create to allow for their selection? To address these questions in the context of serine CUG translation in C.albicans, we have searched for unique structural features in seryl-tRNA(CAG), which translates the leucine CUG codon as serine, and attempted to reconstruct the early stages of this genetic code switch in the closely related yeast species Saccharomyces cerevisiae. We show that a purine at position 33 (G33) in the C.albicans Ser-tRNA(CAG) anticodon loop, which replaces a conserved pyrimidine found in all other tRNAs, is a key structural element in the reassignment of the CUG codon from leucine to serine in that it decreases the decoding efficiency of the tRNA, thereby allowing cells to survive low level serine CUG translation. Expression of this tRNA in S.cerevisiae induces the stress response which allows cells to acquire thermotolerance. We argue that acquisition of thermotolerance may represent a positive selection for this genetic code change by allowing yeasts to adapt to sudden changes in environmental conditions and therefore colonize new ecological niches.

Base Sequence↗
PubMed1997

Transfer RNA recognition by the Escherichia coli delta2-isopentenyl-pyrophosphate:tRNA delta2-isopentenyl transferase: dependence on the anticodon arm structure.

To elucidate the sequence elements required in the anticodon stem for the recognition of Escherichia coli tRNA(Ser) (GGA) by the E. coli isopentenyl-tRNA:A37 transferase (IPTT), which result in the conversion of A37 into isopentenylated i6A37, we have tested and characterized in vitro T7-runoff transcripts of 17 variants of E. coli tRNA(Ser)(GGA) and 7 other tRNAs from E. coli and yeast. Our results indicate that, instead of a stringent specific anticodon stem and loop sequence, the key feature required for the recognition of E. coli tRNAs by IPTT is the A36A37A38 sequence occurring within the seven-membered anticodon loop, and the retention of the standard helical structure and flexibility, especially in the proximal anticodon stem. The G30*U40 mismatch base pair close to the anticodon loop is strictly avoided. The frequent occurrence of a C-G base pair in the three stem locations closest to the loop (positions 29-41, 30-40 and 31-39) or the occurrence of even one such C-G base pair along with some other similarly less suited, but individually tolerated deviations can also totally abolish the A37 isopentenylation of tRNA. For the position 30-40, the G-C base pair is shown uniquely suited, whereas for the adjoining 29-41 stem location, a purine-pyrimidine base pair with pyrimidine on the 3'-side is strongly preferred. Retention of the overall 3D tRNA structure is favorable for isopentenylation and allows some tolerance of proximal stem sequence deviations. Our data suggest a recognition mode that implies the interaction of IPTT with the strictly conserved A36A37A38 sequence and the other functional groups located in the minor groove of the anticodon stem.

Alkyl and Aryl Transferases↗
PubMed1988

Characterization of the phage-specific transfer RNA molecules coded by cholera phage phi 149.

Aminoacylation of tRNA isolated from choleraphage phi 149-infected cells with individual 3H-labeled L-amino acids followed by hybridization with phage DNA revealed that the phage encodes tRNAs specific for arginine, proline, glycine, isoleucine, serine, valine, tyrosine, histidine, lysine, leucine, tryptophan, and aspartic acid. Aminoacylation of phage-coded tRNAs isolated from phage DNA-RNA hybrids also confirmed this observation except for tryptophan.

Bacteriophages↗
PubMed1988

Processing of histidine transfer RNA precursors. Abnormal cleavage site for RNase P.

The 5'-terminal guanylate residue (G-1) of mature Escherichia coli tRNA(His) is generated as a result of an unusual cleavage by RNase P (Orellana, O., Cooley, L., and Söll, D. (1986) Mol. Cell. Biol. 6, 525-529). We have examined the importance of the unique acceptor stem structure of E. coli tRNA(His) in determining the specificity of RNase P cleavage. Mutant tRNA(His) precursors bearing substitutions of the normal base G-1 or the opposing, potentially paired base, C73, can be cleaved at the +1 position, in contrast to wild-type precursors which are cut exclusively at the -1 position. These data indicate that the nature of the base at position -1 is of greater importance in determining the site of RNase P cleavage than potential base pairing between nucleotides -1 and 73. In addition, processing of the mutant precursors by M1-RNA or P RNA under conditions of ribozyme catalysis yields a higher proportion of +1-cleaved products in comparison to the reaction catalyzed by the RNase P holoenzyme. This lower sensitivity of the holoenzyme to alterations in acceptor stem structure suggests that the protein moiety of RNase P may play a role in determining the specificity of the reaction and implies that recognition of the substrate involves additional regions of the tRNA. We have also shown that the RNase P holoenzyme and tRNA(His) precursor of Saccharomyces cerevisiae, unlike their prokaryotic counterparts, do not possess these abilities to carry out this unusual reaction.

Endoribonucleases↗
PubMed1977

Protection of mice against encephalomyocarditis virus infection by preparations of transfer RNA.

Preparations of bacterial transfer RNA (tRNA), give dose-dependent protection of mice against encephalomyocarditis (EMC) virus infection at up to I mg tRNA per mouse with maximum response when the tRNA is administered around 6 h before infection. Protection occurs with intraperitoneally and intravenously administered tRNA against infections by both these routes. In some experiments significant protection occurs by single treatments of tRNA up to 24 h after infection with virus doses of I X LD100. Some tRNA preparations of eukaryotic origin do not give significant protection. Protection is not a feature of all species of bacterial tRNA; partially purified valine, tyrosine and phenylalanine tRNAs from Escherichia coli are not protective. tRNA treatment does not induce circulating interferon nor does it 'hypo-reactivate' the protective effect of poly (I).poly (C) treatment of mice. Humoral and cell mediated immune responses do not seem to be involved in tRNA mediated protection since first, cytosine arabinoside treatment does not affect protection by tRNA; second, serum from mice treated with tRNA and an EMC vaccine does not protect other mice against infection, and third, mice that survive normally lethal infections as a result of tRNA treatment are generally just as susceptible to re-infection as previously untreated, uninfected mice. Silica treatment abolishes protection of mice by tRNA implying that macrophages are necessary. However, tRNA does not seem to act by clearance of virus particles since vaccination of mice by inactivated EMC virus is not affected by tRNA treatment. These results are considered in relation to the presence of a tRNA-like structure in EMC virus RNA and protection of mice by other single stranded polynucleotides.

Animals↗
PubMed2006

Tissue-specific differences in human transfer RNA expression.

Over 450 transfer RNA (tRNA) genes have been annotated in the human genome. Reliable quantitation of tRNA levels in human samples using microarray methods presents a technical challenge. We have developed a microarray method to quantify tRNAs based on a fluorescent dye-labeling technique. The first-generation tRNA microarray consists of 42 probes for nuclear encoded tRNAs and 21 probes for mitochondrial encoded tRNAs. These probes cover tRNAs for all 20 amino acids and 11 isoacceptor families. Using this array, we report that the amounts of tRNA within the total cellular RNA vary widely among eight different human tissues. The brain expresses higher overall levels of nuclear encoded tRNAs than every tissue examined but one and higher levels of mitochondrial encoded tRNAs than every tissue examined. We found tissue-specific differences in the expression of individual tRNA species, and tRNAs decoding amino acids with similar chemical properties exhibited coordinated expression in distinct tissue types. Relative tRNA abundance exhibits a statistically significant correlation to the codon usage of a collection of highly expressed, tissue-specific genes in a subset of tissues or tRNA isoacceptors. Our findings demonstrate the existence of tissue-specific expression of tRNA species that strongly implicates a role for tRNA heterogeneity in regulating translation and possibly additional processes in vertebrate organisms.

Animals↗
PubMed1989

Presence of the hypermodified nucleotide N6-(delta 2-isopentenyl)-2-methylthioadenosine prevents codon misreading by Escherichia coli phenylalanyl-transfer RNA.

The overall structure of transfer RNA is optimized for its various functions by a series of unique post-transcriptional nucleotide modifications. Since many of these modifications are conserved from prokaryotes through higher eukaryotes, it has been proposed that most modified nucleotides serve to optimize the ability of the tRNA to accurately interact with other components of the protein synthesizing machinery. When a cloned synthetic Escherichia coli tRNAPhe gene was transfected into a bacterial host that carried a defective phenylalanine tRNA-synthetase gene, tRNAPhe was overexpressed by 11-fold. As a result of this overexpression, an undermodified tRNAPhe species was produced that lacked only N6-(delta 2-isopentenyl)-2-methylthioadenosine (ms2i6A), a hypermodified nucleotide found immediately 3' to the anticodon of all major E. coli tRNAs that read UNN codons. To investigate the role of ms2i6A in E. coli tRNA, we compared the aminoacylation kinetics and in vitro codon-reading properties of the ms2i6A-lacking and normal fully modified tRNAPhe species. The results of these experiments indicate that while ms2i6A is not required for normal aminoacylation of tRNAPhe, its presence stabilizes codon-anticodon interaction and thereby prevents misreading of the genetic code.

Adenosine↗
PubMed1988

Properties of a transfer RNA lacking modified nucleosides.

A transfer RNA complete devoid of modified nucleosides was synthesized by in vitro transcription, and some of its properties in aminoacylation and protein synthesis in vitro were studied. For this purpose, a plasmid was constructed which contained a glycine tRNA gene from Mycoplasma mycoides under the promoter of the T7 RNA polymerase, as well as a BstNI restriction site at the 3'-end of the tRNA gene. Cleavage of plasmid DNA with BstNI followed by T7 RNA polymerase transcription in vitro yielded an RNA which was processed with M1 RNA, the catalytic subunit of ribonuclease P, to give a tRNA of mature length. The tRNA synthesized in this manner can be esterified with glycine in vitro, and the rate of aminoacylation is the same as when using the corresponding fully modified glycine tRNA from M. mycoides. Furthermore, in protein synthesis in vitro, the tRNA lacking modified nucleosides was essentially as efficient as the corresponding normal glycine tRNA. However, the Escherichia coli extract used in our protein-synthesizing system introduced one modification, pseudouridine, into the in vitro-synthesized tRNA, and it cannot be excluded that this modification has an essential role in protein synthesis.

Adenosine↗
PubMed1974

Transfer RNA biosynthesis: the nucleotide sequence of a precursor to serine and proline transfer RNAs.

The nucleotide sequence of a transfer RNA precursor molecule coded by bacteriophage T4 has been determined. The molecule is a single polynucleotide chain which contains two transfer RNA species that are destined to recognize serine and proline. The 3' -CCA(OH) termini of both mature transfer RNA species are absent in the precursor molecule; these termini must therefore be added enzymatically at a subsequent stage of maturation. Nucleotide residues unique to the precursor are located at both ends of the molecule and between the two transfer RNA sequences.

Base Sequence↗
PubMed1964

EFFECT OF BROMINATION ON THE BIOLOGICAL ACTIVITIES OF TRANSFER RNA OF ESCHERICHIA COLI.

A transfer RNA molecule accepts a particular amino acid from an activating enzyme and subsequently transfers it to the end of a growing peptide chain, in association with ribosomes and messenger RNA. The acceptor and transfer functions of transfer RNA differ in their sensitivity to damage by bromination, and thus appear to comprise different areas on the transfer RNA molecule.

Adenine Nucleotides↗
PubMed1993

Sequence-specific binding of transfer RNA by glyceraldehyde-3-phosphate dehydrogenase.

A transfer RNA (tRNA) binding protein present in HeLa cell nuclear extracts was purified and identified as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Studies with mutant tRNAs indicated that GAPDH recognizes both sequence and structural features in the RNA. GAPDH discriminated between wild-type tRNA and two tRNA mutants that are defective in nuclear export, which suggests that the protein may participate in RNA export. The cofactor nicotinamide adenine dinucleotide disrupted complex formation between tRNA and GAPDH and thus may share a common binding site with the RNA. Indirect immunofluorescence experiments showed that GAPDH is present in the nucleus as well as in the cytoplasm.

Amino Acid Sequence↗
PubMed1969

The transcribing strands of bacillus subtilis DNA for ribosomal and transfer RNA.

H(3)-labeled purified 16S and 23S ribosomal RNA's and transfer RNA's were found to hybridize exclusively with the H strand of the separated complementary strands of B. subtilis DNA. These results indicate that these RNA's are transcribed in vivo from a strand with a composition similar to that from which messenger RNA's are copied and presumably by the same mechanism.

Bacillus subtilis↗