Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Twenty-two borrelidin resistant mutants of Saccharomyces cerivisiae were isolated, studied genetically and their threonyl-tRNA-synthetase was investigated. The borrelidin resistant mutants are classified into four groups. In the first group borrelidin resistance is coupled to the gene HOM3 coding for aspartokinase, in the second group to the gene LEU1. The borrelidin resistance in group three and four is not coupled to anyone of the genetic markers tested. Borrelidin resistance exhibited dominant behavior in all mutants except in the mutant of group 4. The properties of the ThrRS of the mutants of group one, two and four was found to be like the ones of the wild types. However the mutants of group three exhibit a structurally altered ThrRS, which is no longer inhibited by borrelidin.
Mol Gen Genet 1976 Aug 10
PMID:Genetics of borrelidin resistant mutants of Saccharomyces cerivisiae and properties of their threonyl-tRNA-synthetase. 78 24

Conformational transitions in several individual tRNAs (tRNAMetf, tRNAPhe from E. coli, tRNAVal1, tRNASer, tRNAPhe from yeast) have been studied under various environmental conditions. The binding isotherms studies for dyes-tRNA complexes exhibited similarities in conformational states of all tRNAs investigated at low ionic strength (0.01 M NaCl). By contrast, at high ionic strength (0.4 M NaCl or 2 X 10(-4) M Mg2+) a marked difference is found in structural features of tRNAMetf as compared with other tRNAs used. The tRNAMetf is the only tRNA species that does not reveal the strong type of complexes with ethidium bromide, acriflavine and acridine orange.
Mol Biol Rep 1976 Jul
PMID:Conformational peculiarities of tRNAMetf from E. coli as revealed by fluorescent methods. 78 33

The action of S-adenosyl-l-homocysteine (S-Ado-Hcy), its four structural analogues S-Ino-Hcy, S-Guo-Hcy, S-Urd-Hcy, S-Cyd-Hcy and the five corresponding sulfoxides on tRNA methylases has been investigated. The data obtained in the study of overall incorporation of 14CH3-groups into an unfractioned tRNA preparation suggested that both the affinity of the inhibitors tested for various methylases and the type of inhibition were different. The experiments performed with unfractioned tRNA preparation permit to get an idea of the average inhibitory potency of each of the compounds. The study of their action on individual tRNA methylases by means of fractionation of minor components produced demonstrated that the affinity of the inhibitors tested for various methylases was really different. Thus, S-Ado-Hcy, S-Ino-Hcy and S-Urd-Hcy practically do not inhibit m1A methylase but have the highest affinity for m5C methylase. In an experiment with tRNAPhe which is a substrate for a single, namely m5C methylase, the type of inhibition of this methylase by S-Cyd-Hcy was revealed; it was found to be non-competitive with respect to S-Ado-Met, and the S-Cyd-Hcy concentration reducing the methylation by 50 percent was 1.2-10(-4) M.
Mol Biol (Mosk)
PMID:[Inhibiting effect of S-adenosyl-L-homocysteine and its structural analogs on the process of enzymatic methylation of tRNA]. 78 40

The biochemical basis of suppression of a temperature-sensitive alanyl-tRNA synthetase (alaS) mutation by mutational alterations of the ribosome has been investigated. Measurement of the polyU-dependent polyphenylalanine synthesis showed that ribosomes from the suppressor strains are less active than ribosomes from the unsuppressed aminoacyl-tRNA synthetase mutant. In this system no increased translational ambiguity could be detected for the suppressor ribosomes. This fact and also the findings that the ram-1 mutation is not able to suppress the aminoacyl-tRNA synthetase mutation and that presence of the suppressor allele is not accompanied by a measureably improved alanyl-tRNA synthetase activity argue against the possibility that suppression might be due to increased translational misreading rates of the alanyl-tRNA synthetase mRNA. It has been further found that partial suppression of temperature sensitive growth of the alaS mutation can be achieved by independent ribosomal mutations leading to reduced growth rates because of a mutation to antibiotic resistance. Addition of low concentrations of a variety of antibiotics acting at the ribosomal level can also partially revert the temperature-sensitive phenotype of the alaS mutant. Although the possibility cannot be excluded that suppression is due to the stabilisation or activation of the mutant enzyme by some indirect effect of the suppressor ribosomal mutations, the following working hypothesis is favoured at the moment: It is assumed that limitation of the aminoacyl-tRNA synthetase activity in a certain range of the restrictive temperature causes growth inhibition by the premature termination of polypeptide synthesis at the ribosome or by the unbalanced synthesis of the individual cellular proteins under this condition. The mechanism of suppression by ribosomal mutations is proposed to consist of the release of this growth inhibition by the reduction of the rate of polypeptide synthesis, which would keep amino acid incorporation from exceeding the slow charging of tRNA and thus exhausting the pool of charged tRNA. In the suppressor strains, therefore, growth at the semi-restrictive temperature is no longer limited by the aminoacylation of tRNA but by the translational process at the mutated ribosome. This influence of the ribosomal mutation on the speed of translation could be directly or indirectly coupled with an effect on translational fidelity resulting in the prevention of the binding of uncharged or non-cognate charged tRNA or in the tighter binding of peptidyl-tRNA when cognate aminoacyl-tRNA is limiting.
Mol Gen Genet 1976 Nov 24
PMID:Suppression of temperature-sensitive aminoacyl-tRNA synthetase mutations by ribosomal mutations: a possible mechanism. 79 71

Previous studies have shown that iodination of 30 S subunits causes inactivation for both enzymatic fMet-tRNA and non-enzymatic phe-tRNA binding activities. This inactivation was shown to be due to the modification of three to five ribosomal proteins [1]. In this report the role of these proteins in tRNA binding activity has been further studied. Purified ribosomal proteins, isolated from modified subunits, are re-assembled into otherwise unmodified 30 S ribosomes and assayed for tRNA binding capacity. The presence of modified S 3, S 14 and S 19 (S 15) in the reconstituted particle results in substantial reduction of both fMet-tRNA and phe-tRNA binding activities. This reduction in tRNA binding activity does not appear to be due to an assembly defect.
Mol Biol Rep 1976 Nov
PMID:Further evidence for the participation of proteins S 3, S 14 and S 19 in tRNA binding to E. coli 30 S subunits. 79 84

50 S subunits of E. coli ribosomes catalyze the reaction of the 2'(3')-N-(formyl) methionine ester of adenosine 5'-phosphate and Phe-tRNA resulting in peptide bond synthesis. Cytidine 5'-phosphate stimulates this process on 50 S ribosomal subunits as well as on intact ribosomes. The obtained data show that the areas of the peptidyltransferase donor site which binds the 3'-terminal fragment of peptidyl-tRNA possess completely formed structures on 50 S ribosomal subunits.
Mol Biol Rep 1976 Nov
PMID:Catalysis of the peptide bond formation by 50 S subunits of E. coli ribosomes with N-(formyl) methionine ester of adenylic acid as peptide donor. 79 86

The effects of a partial restriction of valyl-tRNA aminoacylation on the synthesis of aminoacyl-tRNA synthetases, ribosomal proteins, and other translation and transcription proteins were examined in otherwise isogenic stringent (relA+) and relaxed (relA1) derivatives of E. coli B. The synthesis of individual ribosomal proteins, elongation factor G, and to a lesser extent elongation factors Tu and Ts, and the valyl- and arginyl-tRNA synthetases was found to be subject to the influence of the stringent control system. The synthesis of the alpha and beta subunits of RNA polymerase and several of the aminoacyl-tRNA synthetases, in contrast, is either not subject to the influence of the stringent control system, or is subject to additional regulatory constraints.
Mol Gen Genet 1976 Dec 22
PMID:The effects of the relA gene on the synthesis of aminoacyl-tRNA synthetases and other transcription and translation proteins in Escherichia coli A. 79 47

A method for the isolation of highly active Escherichia coli ribosomal subunits has been described and used to obtain 30S subunits, which are fully active in the cistron-specific binding of tRNA, and reassociated 70S ribosomes, which are at least 35% active in the synthesis of polypeptides. The dissociation constants (Kd) of the 30S-poly(U)-tRNAPhe complex, which proved to be practically identical for tRNAPhe in the deacylated and aminoacylated forms, as well as for the chemically synthesized peptidyl-tRNA, have been measured. Changes in the binding conditions (temperatures from 0 to 30 degrees, Mg2+ concentrations from 20 to 5 mM, and NH4+ concentrations from 200 to 50mM) have a significant effect on the value of Kd without altering the number of active 30S subunits. It has been shown that the codon-specific binding of tRNA to the 30S subunits is completely reversible. The 30S subunits are not only not inactivated after a single act of binding of a tRNA molecule, but are capable of undergoing this process repeatedly without any appreciable loss in activity.
Mol Biol (Mosk)
PMID:Isolation and study of some properties of the highly active 30S and 50S Escherichia coli ribosomal subunits. 79 55

The absence of summation of the rate of methylation of positionally analogous cytidine residues in tRNA1Val, tRNAPhe, and tRNAMet in the case of simultaneous presence of two substrates in the incubation mixture was demonstrated by the method of mixed substrates. The same result was also obtained in the methylation of A19 (counting from the 3' end of the molecule) in tRNA1Val, tRNAPhe, tRNAfMet, tRNASer, and tRNAGlu individually and in the case of their mixing in pairs. These data are evidence that positionally analogous nucleotides in different RNAs are attacked by the same enzyme. Yeast tRNASer, already possessing a methyl group at the cytidine residue studied, proved to be an effective inhibitor of methylase, forming m5C with valine and phenylalanine tRNAs. The results obtained are evidence that differences in the primary and secondary structures at the site of methylation are not the deciding factors in the interaction of tRNA with methylases.
Mol Biol (Mosk)
PMID:Use of the method of mixed substrates to study the specificity of tRNA methylases. 79 57

In the first part of the review (R. I. Tatarskaya, 1976, Mol. Biol. 10, 235--259) the role of nucleases in the transcription, DNA replication, recombination and reparation was briefly described and discussed. The second part comprises some data on the role of nucleases in tRNA, rRNA, mRNA and DNA processing and mRNA degradation. Brief chapters "Restriction" and "Nucleases and viruses" are included as well.
Mol Biol (Mosk)
PMID:[Nucleases. Biological role]. 80 70


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