Some physiological and genetic properties of a strain of Escherichia coli requiring thymine, arginine and uracil

Kanazir, D.; Barner, Hazel D.; Flaks, Joel G.; Cohen, Seymour S.

doi:10.1016/0006-3002(59)90287-2

Cited by 59 publications

(15 citation statements)

References 14 publications

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“…Whether such synthesis represents residual synthesis of chromosomes initiated prior to amino acid deprivation or initiation of new synthesis by escape from the imposed block is not yet certain. Possible leakiness in the mutants [E. coli 15 TAU is known to be leaky (24)], or protein turnover (25,26) might contribute to such escape. Increasing thymine concentration to 20 y/nml did not prevent residual synthesis, making it unlikely new rounds of synthesis initiated by slight thymine deficiency (14) accounts for the observation.…”

Section: Discussionmentioning

confidence: 99%

Autoradiographic Studies of Bacterial Chromosome Replication in Amino-Acid Deficient Escherichia coli 15T-

Forro¹

1965

Biophysical Journal

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Autoradiographic experiments on amino-acid requiring strains of Escherichia coli T(-) have been performed with fully-labeled cells harvested in log-phase and after periods of amino-acid starvation. The simplest segregation of incorporated label among progeny grown on non-radioactive medium is into two packets. The result corroborates the two-unit model of E. coli DNA inferred from previous studies with partially labeled cells. Following amino-acid starvation, the distribution of label among clones derived from labeled cells indicates cells are grouped into classes having DNA contents in the ratios 1:2:4. The segregation of label among progeny isolated by micromanipulation from such starved cells supports the view that the chromosomes are brought to a state of completed synthesis with different cell classes containing different integral numbers of chromosomes. Infrequent clones interpretable as arising from cells with three chromosomes suggest that the control of replication of chromosomes lying in the same cytoplasm is on an individual basis. The block in DNA synthesis resulting from amino-acid starvation is not perfect. Nevertheless, such starvation permits characterization of the dispersive replication events for more homogeneously labeled and definable DNA units than otherwise possible. The size-frequency distribution of label among progeny following six rounds of chromosome replication is close to that expected from a model of random breakage of linear polymers. The frequency of dispersive events is estimated as 0.5 to 0.7 per chromosome per generation and is only slightly influenced by tritium decays occurring during bacterial growth.

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Section: Discussionmentioning

confidence: 99%

Autoradiographic Studies of Bacterial Chromosome Replication in Amino-Acid Deficient Escherichia coli 15T-

Forro¹

1965

Biophysical Journal

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“…Strain TAU, a polyauxotrophic mutant of E. coli 15, was used in most experiments. This strain, which requires thymine, arginine, and uracil for growth, has been described in earlier reports from this laboratory (9,23). This organism is blocked between ornithine and citrulline (9).…”

Section: Methodsmentioning

confidence: 97%

Polyamines and the Accumulation of Ribonucleic Acid in Some Polyauxotrophic Strains of Escherichia coli

1967

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The cellular accumulations of polyamines and ribonucleic acid (RNA) were compared in the polyauxotrophic mutants of Escherichia coli strain 15 TAU and E. coli K-12 RCrel met-leu-. Putrescine, spermidine, and their monoacetyl derivatives were the main polyamines in both strains, when grown in glucose-mineral medium. No significant degradation of either "4C-putrescine or '4C-spermidine was found in growing cultures of strain 15 TAU, which requires thymine, arginine, and uracil for growth. Experiments with this organism showed that in a variety of different incubation conditions, which included normal growth, amino acid starvation, inhibition by chloramphenicol or streptomycin, or thymine deprivation, a close correlation was seen between the intracellular accumulation of unconjugated spermidine and RNA. In the presence of arginine, the antibiotics stimulated the production of putrescine and spermidine per unit of bacterial mass. Deprivation of arginine also resulted in an increase in the production of putrescine per unit of bacterial mass, most of which was excreted into the growth medium. However, in this system the antibiotics reduced the synthesis of putrescine. Furthermore, streptomycin caused a rapid loss of cellular putrescine into the medium. The latter effect was not seen in anaerobic conditions or in a streptomycin-resistant mutant of 15 TAU. Methionine added to the growth medium of growing TAU not only markedly increased the total production of spermidine, but also increased both the intracellular concentration of spermidine and the accumulation of RNA. Exogenous spermidine extensively relaxed RNA synthesis in amino acid-starved cultures of 15 TAU. Analysis in sucrose density gradients showed that the RNA accumulated in the presence of spermidine was ribosomal RNA. Cells of E. coli K-12 RCrel met-leu-, grown in a complete medium, had approximately the same ratio of free spermidine to RNA as did strain 15 TAU. However, the relaxed strain showed a much lower ratio of putrescine to spermidine than the stringent 15 TAU. Omission of methionine stopped spermidine synthesis and markedly increased both the intracellular accumulation and the total production of putrescine. It seems that a high intracellular level of spermidine acts as a feedback inhibitor in the biosynthesis of putrescine in this strain. The hypothesis that the intracellular concentration of polyamines may participate in the control of the synthesis of ribosomal RNA in bacteria is discussed. The wide distribution of natural polyamines in Tabor and Tabor (25). Models have been deliving organisms has raised the problem of their veloped (11) to explain the binding of spermidine physiological function. It has long been known and spermine to deoxyribonucleic acid (DNA). that polyamines are essential growth factors for The strong affinity of polyamines to nucleic acids several microorganisms. It has been shown that and their occurrence in ribosomal fractions (3, 19, polyamines are able to stabilize membrane struc-27) suggest that polyamines serve as cati...

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“…In this paper, we present the results of several methods utilized to characterize the deoxyribonucleic acid (DNA) contained in these particles. Additional information is presented on the I Presented in part at the 68th Annual Meeting of the American Society for Microbiology, Detroit, Mich., [5][6][7][8][9][10] May 1968. 2 Present address: Department of Biological Sciences, Northern Illinois University, DeKalb, Ill. 60115.…”

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confidence: 99%

Properties of the Deoxyribonucleic Acid Contained in the Defective Particle Coliphage 15

Frampton

Mandel

1970

J Virol

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Escherichia coli strain 15 TAU, which requires thymine, arginine, and uracil for growth and harbors an apparently defective prophage, was induced by exposure to ultraviolet light (580 ergs/mmn) or to mitomycin C (5 jug/ml). Phage particles (coliphage 15) were recovered from the resulting lysate by treatment with deoxyribonuclease, filtration, and several cycles of differential centrifugation. Analysis of the phage particles obtained by using cesium chloride density gradient centrifugation in a preparative ultracentrifuge resulted in the resolution of three components. The major component had a peak density of 1.52 to 1.53 g/cm3 followed by components with densities of 1.5 and 1.49 g/cm3. The guanine plus cytosine content of coliphage 15 deoxyribonucleic acid (DNA) was determined by both analytical ultracentrifugation in cesium chloride and by thermal denaturation in standard saline citrate buffer. Respective values of 46.4 i 1% and 46.6 -i-1% guanine plus cytosine content were obtained. Coliphage 15 DNA formed molecular hybrids with messenger ribonucleic acid (RNA) from both uninduced and ultraviolet-induced cultures of E. coli 15 TAU, but did not hybridize with E. coli ribosomal RNA. The molecular weight of coliphage 15 DNA was determined by constant velocity sucrose density gradient centrifugation to be about 33 X 106 daltons.on July 6, 2020 by guest http://jvi.asm.org/ Downloaded from 9

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Some physiological and genetic properties of a strain of Escherichia coli requiring thymine, arginine and uracil

Cited by 59 publications

References 14 publications

Autoradiographic Studies of Bacterial Chromosome Replication in Amino-Acid Deficient Escherichia coli 15T-

Autoradiographic Studies of Bacterial Chromosome Replication in Amino-Acid Deficient Escherichia coli 15T-

Polyamines and the Accumulation of Ribonucleic Acid in Some Polyauxotrophic Strains of Escherichia coli

Properties of the Deoxyribonucleic Acid Contained in the Defective Particle Coliphage 15

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