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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ninety five rho- mitochondrial DNA's of Saccharomyces cerevisiae were compared for their deletion structure by means of 15 genetic markers and 22 tRNA genes. The patterns of co-deletion and co-retention of different tRNA genes allowed us to determine their positions with respect to each other. The deduced order of tRNA genes was consistent with the order of the genetic markers established by independent genetic approaches. Our previously proposed mitochondrial tRNA gene map has been revised and extended. Transfer RNA genes, corresponding to all 20 aminoacids, and two isoacceptor tRNA genes were localized. The possible position of each tRNA gene has been indicated on the physical map of mitochondrial DNA. Seventeen tRNA genes are carried by a narrow region representing less than 20% of the wild type genome.
Mol Gen Genet 1979 Mar 05
PMID:The genetic map of transfer RNA genes of yeast mitochondria: correction and extension. 37 43

The gene of the amber suppressor tRNA derived from tRNATry, Su+7, has been inserted into a col E1-derived vehicle by selecting for its expression. Despite selection for a suppressor phenotype, and the plasmid's stable presence at ca. 180 copies cell during balanced growth, the level mature tRNA maintained by the gene is less than that of the normal haploid tRNATry locus in the bacterial chromosome. Transfer RNA genes, both the plasmid Su+7 gene and chromosomal tRNA's are expressed during inhibition of protein synthesis. During, e.g. chloramphenicol inhibition, Su-7 and Su+7 tRNA can be elevated similarly in the plasmid-containing cell; Su+7 reaches levels of molecules/cell which ordinarily characterize a major tRNA. The recombinant plasmid, but not the cloning vehicle alone, has a more general effect on tRNA levels; accumulation of tRNA from three chromosomal tRNA loci including tRNATry, continues during extensive isoleucine limitation. The plasmid therefore contains a locus which probably alters the relaxed-stringent circuit, whose effect is disseminated to at least 3 widely separated loci.
Mol Gen Genet 1979 Mar 05
PMID:Isolation and properties of a plasmid which expresses the E. coli Su+7 amber suppressor tRNA gene. 37 44

Using the pMB9 recombinant plasmid pMY3, which contains a functional gene for the tRNATry mutant Su+7, the EcoRI fragment containing the tRNATry gene is mapped and oriented with respect to the HindIII site in the tetracycline region of pMB9. Complete HpaII and HaeIII maps of the EcoRI fragment are derived. The Su+7 tRNA gene is placed by hybridization to these fragments, and the tRNA gene is oriented by using the restriction sites for HinfI, TaqI, and HpaII in the tRNA gene itself. A tRNAAsp gene is shown to lie adjacent to tRNATry, and is also placed and oriented in the map. The RI fragment itself originates in a locus adjacent to, and transcribed in the same direction as, the ribosomal RNA genes of phi 80d3. The implications of the structure of the cloned DNA for its previously measured regulatory and tRNA gene activities are discussed. In particular, the effect on the regulation of RNA synthesis is attributable to an E. coli DNA sequence, but cannot be due to the presence of a normal tRNA promoter on the plasmid.
Mol Gen Genet 1979 Mar 05
PMID:The structure of the DNA containing the E. coli tRNATry gene. 37 45

The plasmid pMY3, which was constructed so as to express the Su+7 amber suppressor tRNA gene, also relaxes control of stable RNA synthesis in stringent cells. The relaxation is not growth medium or strain-dependent and does not occur in the presence of the vehicle alone. When expression of the effective sequence is diminished, in a lysogen of phi 80d3 ilv+Su+7, the sequence no longer affects RNA synthesis. The relaxation is general, extending to all or almost all tRNA loci, including tRNAs located in the ribosomal spacer regions, and to all ribosomal RNAs. Relaxed plasmid-carrying strains are still able to elevate guanosine tetra- and penta-phosphate levels in response to amino acid starvation, but steady state levels are somewhat diminished. Aminoacyl-tRNA falls to control levels when the plasmid-carrying strain is deprived of amino acid. Therefore, the relaxed strain perceives amino acid starvation, but does not respond normally. These properties define a novel locus which relaxes stringent control.
Mol Gen Genet 1979 Mar 05
PMID:Relaxation of stable RNA synthesis by a plasmid-borne locus. 37 46

A procedure for the large-scale isolation of leucyl-tRNA synthetase from E. cole MRE 600 is described: The enzyme was purified about 320-fold to homogeneity by precipitation with cetyl-trimethyl-ammonium bromide, two consecutive chromatographies on DEAE-cellulose and three on hydroxyapatite with an over-all yield of 4%. The molecular weight of leucyl-tRNA synthetase from E. coli MRE 600 was found to be 99 000 daltons. Bindings studies by ultracentrifugation and equilibrium partition showed that the enzyme binds leucine, leucyl-adenylate and tRNA Leu, each in a 1 : 1 stoichiometry. For ATP only a very weak binding to the enzyme could be observed, which did not allow the evaluation of the complex stoichiometry. The presence of ATP was not required for the binding of leucine or tRNA to leucyl-tRNA synthetase from E. coli MRE 600.
Mol Cell Biochem 1979 Apr 02
PMID:Isolation and binding properties of leucyl-tRNA synthetase from Escherichia coli MRE 600. 37 93

It has been shown that 50S subunits of E. coli MRE-600 ribosomes catalyze the reaction of N-(formyl)-methionyl ester of adenosine 5'-phosphate acting as peptide donor, with Phe-tRNA or CACCA-Phe serving as a peptide acceptor. The reaction is stimulated by cytidine 5'phosphate and inhibited by lincomycin, puromycin and chloramphenicol. The obtained results show that the structure of the donor site of peptidyltransferase is completely assembled on the 50S subunit and 30S subunit is not required for its formation.
Mol Biol (Mosk)
PMID:[Fragment reaction catalyzed by E. coli ribosomes]. 37 8

Aminoacyl tRNA synthetases discriminate between tRNA species by a highly specific mechanism. Physical and chemical studies indicate that the synthetases bind along and around the inside of the three-dimensional L-shaped tRNA structure. Studies of mutant tRNAs that affect synthetase interaction tend to confirm this conclusion. However, in contrast to proteins that recognize a specific block of contiguous nucleotide units (e.g., repressors, restriction enzymes, etc.), synthetases appear to interact with spatially disperse elements of the structure. Available evidence suggests that tRNA binding clefts on various synthetases may be roughly similar, with specificity being achieved by the choice of amino acid residues in a few critical positions in the tRNA binding clefts. With this idea in mind, it should be possible to introduce amino acid substitutions into the binding clefts and thereby change tRNA recognition specificity. This has been attempted (by genetic manipulations) and a mutant alanine tRNA synthetase with altered tRNA recognition has been isolated. This enzyme can attach alanine to isoleucine specific tRNA. When presented with valine specific tRNA, a tRNA similar in some structural features to the isoleucine specific tRNA, or with the structurally quite different tyrosine specific tRNA, no significant aminoacylation occurs. Thus, a precise specificity alteration can occur through mutation; this result supports the idea of similarities in synthetase binding clefts, with specificity being achieved by the positioning of amino acids at critical positions in these clefts. Finally, further data have been obtained on the issue of possible transient covalent bond formation between synthetases and tRNAs, as a critical part of the interaction.
Mol Cell Biochem 1979 May 06
PMID:Recent results on how aminoacyl transfer RNA synthetases recognize specific transfer RNAs. 38 92

The influence of modification of Phe-RSase from E. coli MRE-600 by lysine- and arginine-specific reagent 2,4-pentandione on the Phe-RSase.tRNAPhe interactions was investigated. It was shown that modification of Phe-RSase with 2,4-pentandion leads to a decrease of the aminoacylation rate without any influence on the value of Km for tRNAPhe in this reaction and only a slight increase of the value of Kdiss for Phe-RSase.tRNAPhe complex. The log Km (Km-1)--ionic strength dependence for native enzyme and log Kdiss (K-1diss) for native enzyme and two forms modified on arginine and lysine residues were investigated. Results were interpreted quantitatively by Debye--Huckel approximation for two spherical macroions and by Daune approximation assuming that the region of tRNA implicated in ionic interactions is locally a cylindrical polyelectrolyte. It was shown that there are 2-4 electrostatic contacts in Phe-RSase.tRNAPhe interactions in limits of both approximations; modification of arginine residues in Phe-RSase doesn't change the number of electrostatic contacts, modification of lysine residues leads to an increase in the number of contacts. It was assumed that there are lysine residues in Phe-RSase essential for the tRNAPhe recognition. The possibility of participation of negative amino acid residues in electrostatic interactions with tRNAPhe is not excluded.
Mol Biol (Mosk)
PMID:[Influence of the modification of Phe-tRNA synthetase from Escherichia coli by lysine- and arginine-specific reagent on the ionic interactions of the enzyme with tRNA Phe]. 38 96

When cells of Escherichia coli are labeled with 32Pi for long periods of time and the cell content is subjected to electrophoresis in polyacrylamide gels, an RNA band appears which is about 10S in size. This band seems to contain three conformers. After treatment with formamide only a single band appears in this region of the gel, which contains 550 nucleotides as determined from its mobility. The complexity of the fingerprint of this material, after digestion with T1-RNase, is in agreement with the size as determined by the mobility, this confirming that indeed it is a single molecule. Composition of the T1-oligonucleotides was determined by digesting the T1-generated oligonucleotides with pancreatic RNase and T2-RNase. The quantitative and qualitative analysis of these digestions suggest that 10S RNA contains 609 nucleotides. The molecule contains, besides the four regular bases, one copy per molecule of the modified base pseudouridine. 10S RNA cannot be processed by cell extracts to tRNA-sized molecules and does not bind significantly to ribosomes, hence it is unlikely to be a tRNA precursor or an mRNA.
Mol Gen Genet 1979 Jul 02
PMID:Characterization of 10S RNA: a new stable rna molecule from Escherichia coli. 38 59

ATP gamma-(p-azidoanilidate) (1) and ATP gamma-(p-azidobenzyl)-methylanilidate (2) were shown to be competitive inhibitors for ATP and amino acid in tRNA aminoacylation catalyzed by E. coli MRE-600 phenylalanyl-tRNA synthetase (E.C.6.1.1.20). Low concentration (10(-5)--10(-6) M) of either ATP, gamma-anilidate or GMP stimulates the aminoacylation of tRNA suggesting their interaction with some nucleotide binding sites of the enzyme other than catalytic ones. Covalent photobinding of (1) to the enzyme does not inhibit aminoacylation, nor does it prevent nucleotides from activating the enzyme. UV-irradiation of the synthetase in the presence of (2) results in complete inactivation of the enzyme which can be prevented by phenylalanine or phenylalanine-ATP to save 50% of the enzyme activity but not ATP and tRNA. The photobinding of (2) to the enzyme in the presence of phenylalanine and ATP removes the activation of the enzyme by nucleotides suggesting that both the catalytic and effector sites of the synthetase are blocked in the same manner by compound (2).
Mol Biol (Mosk)
PMID:[Influence of the structure of photoreactive ATP analogs on the affinity modification of phenylalanyl-tRNA synsthetase. Modification of the enzyme at two types of nucleotide sites]. 38 88


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