Modification of valyl tRNA synthetase by bacteriophage in Escherichia coli

Chrispeels, Maarten J.; Boyd, Robert F.; Williams, Luther S.; Neidhardt, Frederick C.

doi:10.1016/0022-2836(68)90421-x

Cited by 65 publications

(31 citation statements)

References 12 publications

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“…Preparation of crude extracts and enzyme assays. The preparation of crude extracts and the determination of histidyland leucyl-tRNA synthetases activities by the 14C-labeled amino acid attachment assay were as described by Chrispeels et al (2), with the exception that incubation time was 5 min. Protein was determined by the method of Lowry et al (7).…”

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confidence: 99%

First Enzyme of Histidine Biosynthesis and Repression Control of Histidyl-Transfer Ribonucleic Acid Synthetase of Salmonella typhimurium

Coleman

Williams

1974

J Bacteriol

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The regulation of formation of histidyl-transfer ribonucleic acid (tRNA) synthetase was examined in strains of Salmonella typhimurium. When the first of the histidine-forming enzymes was wild type, the presence of 2-thiazolealanine in the growth medium prevented repression of histidyl-tRNA synthetase formation elicited by the addition of 1, 2, 4-triazole-3-alanine to these cultures. Conversely, thiazolealanine had no effect on repression of histidyl-tRNA synthetase formation by triazolealanine in hisG mutant strains. These data suggest a relationship between the control of histidyl-tRNA synthetase formation and the functional state of the histidine operon. 390 on July 31, 2020 by guest

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First Enzyme of Histidine Biosynthesis and Repression Control of Histidyl-Transfer Ribonucleic Acid Synthetase of Salmonella typhimurium

Coleman

Williams

1974

J Bacteriol

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“…Preparation of cell extracts. As described by Chrispeels et al (2), cells were subjected to sonic treatment with a Branson sonic oscillator. Protein content of extracts was determined by using the method of Lowry et al (4).…”

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“…The RNA content was determined by absorbance at 260 nm by using 24 absorbancy units to equal 1 mg of RNA per ml. The tRNA samples were used in the standard attachment assay system, with 14C-histidine as the amino acid substrate and with excess enzyme, as described elsewhere (2).…”

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Regulation of Histidyl-Transfer Ribonucleic Acid Synthetase Formation in a Histidyl-Transfer Ribonucleic Acid Synthetase Mutant of Salmonella typhimurium

McGinnis

Williams

1972

J Bacteriol

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Control of formation of the histidyl-transfer ribonucleic acid (tRNA) synthetase with an increased Km for histidine was studied in a hisS mutant of Salmonella typhimurium. Histidine restriction of both the hisS and hisS+ strains resulted in a derepression of synthesis of histidyl-tRNA synthetase. When grown in a concentration less than the Km (100 ,g/ml) of L-histidine, the hisS mutant maintained a higher level of histidyl-tRNA synthetase than the hisS+ strain. Addition of excess amounts of L-histidine to the growth medium of the hisS mutant culture grown with 100 ,gg of L-histidine per ml resulted in a repression of histidyl-tRNA synthetase formation to equal that of the hisS+ strain grown in 100 ,ug of L-histidine per ml. These data confirm previous findings that histidine tRNA is involved in the repression of synthesis of histidyl-tRNA synthetase.

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“…In a sense, the suggestion that the mitochondrial leucyl-tRNA synthetase is a modified version of the cytoplasmic enzyme is analogous to the observed alteration of the host valyl-tRNA synthetase upon infection of E. coli with T4. 9 The apparent deficiency of mitochondrial leucyl-tRNA synthetase in 45208t raises some doubt as to the validity of the previously offered explanations of the temperature-sensitive (conditional lethal phenotype of the mutant. Since the mutant, when grown at high temperature, was found to produc2 a variety of structurally altered enzymes and since the temperature effect was markedly reversed by added leucine, it seemed reasonable to relate amino acid misrecognition at elevated temperatures to the alteration of the leucine-binding property of the mutant leucyl-tRNA synthetase.…”

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Evidence for the involvement of a nuclear gene in the productin of the mitochondrial leucyl-tRNA synthetase of Neurospora.

Gross¹,

McCoy²,

Gilmore³

1968

Proc. Natl. Acad. Sci. U.S.A.

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The mitochondria of Neurospora have been shown to contain many elements of the machinery of protein synthesis that are distinctly different from those of the rest of the cell. The differences observed in the structural and functional specificity of mitochondrial and "cytoplasmic" ribosomes,I transfer RNA's,2 and several aminoacyl-tRNA synthetases3 suggest that protein synthesis in mitochondria and the cytoplasm may be regulated by distinctly different control mechanisms. In view of this, it has become important to determine whether the structure of the various elements of mitochondrial protein synthesis is specified by the mitochondrial genome.The availability of a strain of Neurospora 45208t, bearing a nuclear gene mutation that results in the production of the major "cytoplasmic" leucyl-tRNA synthetase with a two-to threefold higher K8 for leucine than normal4 offered a unique opportunity to determine whether the structure of the corresponding mitochondrial leucyl-tRNA synthetase is determined by the same or an independent genetic element. If, for example, the mitochondrial leucyl-tRNA synthetase were indeed specified by the mitochondrial genome, strain 45208t should produce, during growth, a normal mitochondrial leucyl-tRNA synthetase. It was surprising to find, as we show below, that instead of a normal mitochondrial leucyl-tRNA synthetase or an enzyme with an altered affinity for leucine the mitochondria of 45208t contain, at best, very little leucyl-tRNA synthetase activity while possessing a near normal amount of phenylalanyl-tRNA synthetase activity.Materials and Methods.-Biological: STD8A of Neurospora crassa was the wild-type strain used and 45208t-2-15A the mutant. Both strains were grown in 6-liter batches of synthetic medium with 1.0% sucrose as the carbon source and supplemented with 75 mg leucine per liter. Routinely flasks were inoculated with about 105 conidia and incubated with aeration for 40 hr at 34°. Although the growth of 45208t is restricted at 340 in the absence of leucine, growth is near normal in liquid medium supplemented with leucine. Cultures of the mutant were checked for genetic homogeneity before use by testing them for growth on leucine-containing medium for 48 hr at 39°. At this temperature, 45208t hardly grows even when provided with leucine. The mutant is fairly unstable upon prolonged vegetative subculture and frequent purification by conidial reisolation is required.Preparation of enzyme extracts: Mycelia were collected by filtration and washed with water. All subsequent operations were carried out at 0-4°. To each gm wet weight of mycelia 10 ml of 0.05 M tris(hydroxymethyl)aminomethane HCl, pH 7.2 (Tris buffer) containing 5 X 10-4 M dithiothreitol (DTT) were added and the suspension was homogenized at 0-4o with a PT20 Polytron for 2 min, then sonicated intermittently for about 5 min per 100 ml of extract with a Branson 20-kc sonifier. Cell debris and subcellular particles were removed first by centrifugation at 8,000 X g for 15 min, then by centrifugation for 1 hr at 80,00...

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Modification of valyl tRNA synthetase by bacteriophage in Escherichia coli

Cited by 65 publications

References 12 publications

First Enzyme of Histidine Biosynthesis and Repression Control of Histidyl-Transfer Ribonucleic Acid Synthetase of Salmonella typhimurium

First Enzyme of Histidine Biosynthesis and Repression Control of Histidyl-Transfer Ribonucleic Acid Synthetase of Salmonella typhimurium

Regulation of Histidyl-Transfer Ribonucleic Acid Synthetase Formation in a Histidyl-Transfer Ribonucleic Acid Synthetase Mutant of Salmonella typhimurium

Evidence for the involvement of a nuclear gene in the productin of the mitochondrial leucyl-tRNA synthetase of Neurospora.

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