Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Temperature-induced conformational changes in the anticodon region of yeast tRNATyr were studied by EPR spectroscopy. The spin label 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl was attached to the N6-(delta2-isopentenyl)-adenosine residue in tRNATyr, previously made reactive by iodination. The labelled tRNATyr gave an asymmetrical triplet spectrum typical of rapidly tumbling nitroxide, with a rotational correlation time (tauc) of 0.65 ns. Spin-labelled tRNATyr was exposed to heating and cooling in three different buffers each with or without MgCl2. In each case the Arrhenius plot of --log tauc vs. inverse absolute temperature gave two straight lines, intersecting at a critical temperature (tcr). Above tcr, the anisotropy of the spectrum was not reduced and the activation energy of motion increased, indicating that the transition is associated with a conformational change of the macromolecule. Transitions in 0.05 M potassium phosphate (pH 8.0) and 0.02 M Tris - HC1 (pH 7.0) were observed at potassium phosphate (pH 8.0) and 0.02 M Tris - Hc1 (pH 7.0) were observed at approx. 37 degrees C. When 0.01 M mgCl2 was present in these buffers, transitions were shifted to 46 degrees and 53 degrees C, respectively. Transitions in 0.01 M sodium cacodylate were observed at temperatures which are significantly lower. Since all these transitions occur at temperatures considerably below those required to melt the helical regions of tRNA, and at least approximately 10 degrees C below those reported to break tertiary interactions, it is supposed that they reflect some reorientation of the anticodon region, e.g. a change in tilt of the bases.
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PMID:Conformational changes in yeast tRNATyr revealed by EPR spectra of spin-labelled N6-(delta2-isopentenyl)-adenosine residue. 20 Feb 69

Purified phenylalanyl-tRNA synthetases present in chloroplasts, mitochondria and cytoplasm of green and bleached Euglena gracilis strains, respectively, are able to synthesize diadenosine 5',5'''-P1,P4-tetraphosphate (Ap4A). Ap4A synthesis is strictly dependent on zinc ions. This is the first evidence that chloroplasts should be able to synthesize Ap4A. Synthesis of Ap4A by phenylalanyl-tRNA synthetases of the three compartments of a plant cell or by other enzymes such as Ap4A phosphorylase is discussed.
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PMID:Synthesis of diadenosine 5',5'''-P1,P4-tetraphosphate by organellar and cytoplasmic phenylalanyl-tRNA synthetases of Euglena gracilis. 340 1

The synthesis of diadenosine 5',5'''-P1,P4-tetraphosphate (Ap4A) can be catalyzed in vitro by a tetrameric tRNA synthetase complex from rat liver containing two lysyl-tRNA synthetase and two arginyl-tRNA synthetase subunits. This reaction required ATP, AMP, 50-100 microM zinc, and inorganic pyrophosphatase. We show here that AMP can be omitted from the reaction and that the zinc levels can be markedly reduced provided catalytic amounts of tRNA(Lys) are added to the reaction mixture. Ap4A synthesis with purified tRNA(Lys) isoacceptors showed that the minor species, tRNA(4Lys), was 3-fold more active than either of the two major tRNA(Lys) species, tRNA(2Lys) and tRNA(5Lys). No activity could be demonstrated with tRNA(Lys) from Escherichia coli or with tRNA(Lys) or tRNA(Phe) from yeast. Aminoacylation of tRNA(4Lys) was strictly required as determined by the fact that Ap4A synthesis was not observed until aminoacylation was nearly complete, inhibitors of aminoacylation blocked Ap4A synthesis, and there was a strict requirement for added lysine. None of the above observations could be demonstrated, however, when lysyl-tRNA(Lys) was directly supplied to the reaction mixture. Optimum Ap4A synthesis was obtained by the addition of 1 mol of tRNA(Lys)/mol of the synthetase complex. This reaction is unique because it does not require the prior formation of an aminoacyl-AMP intermediate and because it can actively synthesize Ap4A at physiological zinc concentrations. The preferential role for tRNA(4Lys) in Ap4A synthesis is consistent with its prior implication in cell division.
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PMID:A preferential role for lysyl-tRNA4 in the synthesis of diadenosine 5',5'''-P1,P4-tetraphosphate by an arginyl-tRNA synthetase-lysyl-tRNA synthetase complex from rat liver. 364 96

Native and modified phenylalanine transfer ribonucleic acid (tRNAPhe) can modulate phenylalanine-dependent adenosine triphosphate--inorganic [32P]pyrophosphate (ATP--[32P]PPi) exchange activity via inhibition of adenylate synthesis. Inhibition is visualized if concentrations of L-phenylalanine, ATP, and pyrophosphate are subsaturating. In the proposed mechanism, tRNAPhe is a noncompetitive inhibitor at conditions where only one of the two active sites per molecule of enzyme is occupied by L-phenylalanine, ATP, and pyrophosphate. At saturating concentrations of these reactants, both active sites are occupied and, according to the model, inhibition is eliminated. Occupation by these reactants is assumed to follow homotropic negative cooperativity. The type of effects depends on modification of tRNAPhe. Native tRNAPhe, tRNA2'-dAPhe, and tRNAoxi-redPhe are inhibitors, tRNAPhepCpC has no effect, and tRNAoxPhe is an activator. Kinetics of activation by tRNAoxPhe are slow, following the time course of Schiff base formation and subsequent reduction by added cyanoborohydride. Besides showing that a putative enzyme amino group is nonessential for substrate binding and adenylate synthesis, this result may suggest that an enzyme amino group could interact with the 3'-terminal adenyl group of cognate tRNA. In the case of asymmetrical occupation of the enzyme active sites by all of the small reactants ATP, L-phenylalanine, and pyrophosphate, the interaction with the amino group might trigger the observed noncompetitive inhibition of the pyrophosphate exchange by tRNAPhe.
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PMID:Phenylalanyl-tRNA synthetase of baker's yeast. Modulation of adenosine triphosphate-pyrophosphate exchange by transfer ribonucleic acid. 626 48

We describe improve enzymatic methods for sequencing method for sequencing DNA. They are based on partial digestion of duplex DNA with exonuclease III to produce DNA molecules with 3' ends shortened to varying lengths, followed by repair synthesis to extend and label the 3' ends. After asymmetrical cleavage of the DNA with a restriction enzyme, the labeled products are separated by gel electrophoresis and the sequence read from the autoradiogram. The entire procedures, beginning with unrestricted DNA and followed through gel electrophoresis, takes only one day for sequencing both strands of the DNA molecule. These methods are especially suitable for sequencing DNA cloned in plasmid vectors, and they greatly extend the usefulness of the dideoxynucleotide chain termination method of Sanger et al. (Proc. Natl. Acad. Sci. USA 74, 5463, 1977). Using these methods we have determined the sequence of a 410 base pair fragment which includes the yeast SUP3 tyrosine tRNA gene.
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PMID:New rapid methods for DNA sequencing based in exonuclease III digestion followed by repair synthesis. 628 30

Premutational lesions produced by ultraviolet radiation in the Gln2 tRNA genes of E. coli B/r show differing sensitivities to a mutation avoidance phenomenon known as mutation frequency decline (MFD). A mutation event that changes the wild-type gene to an amber (UAG) suppressor is normally sensitive to MFD. Mutation of this amber suppressor to an ochre (UAA) suppressor is not sensitive to MFD. These two mutation events occur in the same anticodon region of the DNA. The dissimilarity of MFD sensitivity between these two mutations may result because the respective premutational photoproducts for the two are located in opposite strands of duplex DNA. To examine the effect of strand position of the premutational lesions on MFD, recombinant lambda phage were constructed that contained the amber suppressor as a mutation target in the two possible orientations. Comparison of MFD in bacterial lysogens containing either of the two types of recombinant prophage indicated that reversing the orientation of the target sequence relative to adjacent bacterial DNA had no effect on MFD. Since rotational inversion of the target sequence did not alter the sensitivity to MFD of mutation occurring at the cloned target gene, the antimutation process inherent to MFD can not be attributed to an asymmetrical interaction between the template strands and the DNA-replication complex.
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PMID:UV-mutagenesis at a cloned target sequence: converted suppressor mutation is insensitive to mutation frequency decline regardless of the gene orientation. 639 68

The C-terminal domain (residues 320-419) of tyrosyl-tRNA synthetase (TyrRS) from Bacillus stearothermophilus is disordered in the crystal structure. Its function consists of binding the anticodon of tRNA(Tyr). We undertook to characterize its conformational state. A hybrid between the C-terminal fragment and a His-tag sequence was constructed and purified in large amounts. Analyses by mass spectrometry and analytical ultracentrifugation showed that the C-terminal fragment, thus purified, was not degraded and that it neither dimerized nor aggregated. Its far- and near-UV circular dichroism spectra revealed a high content in secondary structures and an asymmetrical environment of its aromatic residues. Each spectrum could be reconstructed by the difference between the corresponding spectra for the full-length TyrRS and for its N-terminal fragment. The Stokes radius of the C-terminal fragment, measured by size exclusion chromatography, indicated a condensed globular state. The fluorescence of ANS (a small hydrophobic probe) showed that the surface of the C-terminal fragment was more hydrophilic than that of a molten globule. These results on the C-terminal fragment and our previous observations that it can undergo cooperative transitions, demonstrated the following points: it is not in a disordered or molten globular state, it has a defined and stable three-dimensional structure, its structures are similar in its isolated and integrated forms, and the apparent disorder in the crystals of the full-length synthetase must be due to the flexibility of the polypeptide segment that links the N- and C-terminal domains. Thus, TyrRS has not evolved strong noncovalent interactions between its catalytic and anticodon-binding domains, contrary to the other synthetases.
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PMID:The anticodon-binding domain of tyrosyl-tRNA synthetase: state of folding and origin of the crystallographic disorder. 1067 23

We discovered a new homoplasmic mutation in the mitochondrial cysteine tRNA of a 60-year-old Caucasian male suffering from asymmetrical pure lower motor neuron disease (MND) and temporal lobe epilepsy (TLE). Furthermore, titrations with Amytal, an inhibitor of NADH:CoQ oxidoreductase, revealed mild mitochondrial dysfunction in skeletal muscle tissue, which was described in patients with MND in an earlier report. The mutation was undetectable in 155 Caucasian controls of both sexes, in 40 MND patients and in 13 individuals suffering from TLE. It was, however, detected in a heteroplasmic state in the patient's mother, who did not suffer from a neurological disorder. Since this rare mutation affected a nonconserved base position and was not observed in MND or TLE materials, its relation to disease remains unclear.
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PMID:Mitochondrial tRNA(Cys) mutation A5823G in a patient with motor neuron disease and temporal lobe epilepsy. 1073 84

Trbp111 is a 111 amino acid Aquifex aeolicus structure-specific tRNA-binding protein that has homologous counterparts distributed throughout evolution. A dimer is the functional unit for binding a single tRNA. Here we report the 3D structures of the A.aeolicus protein and its Escherichia coli homolog at resolutions of 2.50 and 1.87 A, respectively. The structure shows a symmetrical dimer of two core domains and a central dimerization domain where the N- and C-terminal regions of Trbp111 form an extensive dimer interface. The core of the monomer is a classical oligonucleotide/oligosaccharide-binding (OB) fold with a five-stranded ss-barrel and a small capping helix. This structure is similar to that seen in the anticodon-binding domain of three class II tRNA synthetases and several other proteins. Mutational analysis identified sites important for interactions with tRNA. These residues line the inner surfaces of two clefts formed between the ss-barrel of each monomer and the dimer interface. The results are consistent with a proposed model for asymmetrical docking of the convex side of tRNA to the dimer.
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PMID:Crystal structure of trbp111: a structure-specific tRNA-binding protein. 1110 1

Estimates of African, European, and Amerindian contributions to the gene pool of 11 predominantly African-derived South American populations were obtained using five autosomal and one Y chromosome hypervariable loci, as well as mitochondrial DNA (sequences of the first hypervariable segment of the control region, plus two restriction sites and the presence or absence of the CoII/tRNA(Lys) intergenic 9-bp deletion). The three latter characteristics are reported here for the first time for 42 individuals living in three Brazilian populations. Thirty-eight sequences were identified in these persons; 17 (45%) could be classified as being of African, 4 (11%) of Amerindian, and 2 (5%) of European origin. Evidence for asymmetrical matings in relation to sex and ethnic group was obtained for nine of the 11 populations. The most consistent finding was the introduction of European genes through males, but the results differ in the several communities, indicating the importance of local factors in such interactions. Am. J. Hum. Biol. 11:551-563, 1999. Copyright 1999 Wiley-Liss, Inc.
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PMID:African-derived South American populations: A history of symmetrical and asymmetrical matings according to sex revealed by bi- and uni-parental genetic markers. 1153 75


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