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Showing papers on "Escherichia coli published in 1969"


Journal ArticleDOI
TL;DR: Intercistronic complementation was observed between three classes of restriction and modification mutants of E. coli B, indicating that at least three cistron (the ram cistrons) are involved in the genetic control of the [restriction and modification of DNA].

3,656 citations


Journal ArticleDOI
TL;DR: Exonuclease function of DNA polymerase from Escherichia colis, discussing hydrolysis of polydeoxyribonucleotides and resistancy of oligonucleotide.

705 citations


Journal ArticleDOI
20 Dec 1969-Nature
TL;DR: By testing indiscriminately several thousand colonies of mutagenized E. coli, a mutant has been isolated that on extraction proves to have less than I per cent of the normal level of DNA polymerase.
Abstract: By testing indiscriminately several thousand colonies of mutagenized E. coli, a mutant has been isolated that on extraction proves to have less than I per cent of the normal level of DNA polymerase. The mutant multiplies normally but has acquired an increased sensitivity to ultraviolet light.

696 citations


Journal ArticleDOI
01 Mar 1969-Nature
TL;DR: Autoradiography has revealed in a stringent strain of E. coli two compounds that seem to be involved in the inhibition of the synthesis of RNA.
Abstract: Autoradiography has revealed in a stringent strain of E. coli two compounds that seem to be involved in the inhibition of the synthesis of RNA.

690 citations


Journal ArticleDOI
TL;DR: Comparison of properties of the system regulating the synthesis of these compounds with those of the amino acid control of RNA biosynthesis suggests that the unusual compounds participate in an early step in the mechanism which leads to the slowing ofRNA biosynthesis during amino acid starvation of stringent strains.

443 citations


Journal ArticleDOI
26 Apr 1969-Nature
TL;DR: The streptomycin locus of E. coli specifies a 30S ribosomal protein which determines the sensitivity of the 30S subunit to strePTomycin and streptomecin induced errors of translation.
Abstract: The streptomycin locus of E. coli specifies a 30S ribosomal protein which determines the sensitivity of the 30S subunit to streptomycin and streptomycin induced errors of translation.

435 citations


Journal ArticleDOI
TL;DR: Charge considerations, enzyme degradation studies, and labilities in acid and alkali lead to a structural assignment for MS I of guanosine 5'-diphosphate or 3'- or 2'-dphosphate (ppGpp).

352 citations


Journal ArticleDOI
TL;DR: An examination of messenger RNA relatively specific for the lactose operon suggests that specific chromosomal genes may diverge more or less than the genome as a whole and Ribosomal ribonucleic acid (RNA)-specific sequences are conserved among most enterobacteria.
Abstract: Polynucleotide relationships were examined among many representatives of the Enterobacteriaceae by means of agar, membrane filter, and hydroxyapatite procedures. The amount of deoxyribonucleic acid (DNA) that reassociated was dependent, especially in interspecific reactions, on the annealing temperature. In only three cases: Escherichia coli-Shigella flexneri, Salmonella typhimurium-S. typhi, and Proteus mirabilis-P. vulgaris, was relative interspecific duplex formation 80% or higher. In most cases interspecies DNA duplex formation was 40% or less of that obtained from intraspecies DNA reassociation reactions. The stability of E. coli-S. flexneri DNA duplexes formed at either 60 or 75 C was virtually identical to that of homologous E. coli DNA duplexes, and the degree of interspecies duplex formation was minimally affected by the temperature increase (86% at 60 C; 77% at 75 C). The thermal stability of DNA duplexes formed at 60 C between DNA from E. coli and DNA from strains of Aerobacter aerogenes, S. typhimurium, S. typhi, and P. mirabilis was about 12 to 14 C below that of reassociated E. coli DNA. At 75 C, the formation of the interspecific DNA duplexes was markedly decreased, but the stability of the DNA able to reassociate at this temperature approximated that of reassociated E. coli DNA. The degree of reassociation and the thermal stability of E. coli-S. flexneri DNA duplexes suggests relatively little evolutionary divergence in these organisms. The other enterobacteria tested, however, have diverged to a point where less than one-half of their DNA can reanneal with E. coli DNA at 60 C and less than 10% reacts at 75 C. The degree of divergence between various enterobacteria does not appear to be uniform along the DNA molecule. Ribosomal ribonucleic acid (RNA)-specific sequences are conserved among most enterobacteria. An examination of messenger RNA relatively specific for the lactose operon suggests that specific chromosomal genes may diverge more or less than the genome as a whole.

276 citations


Journal ArticleDOI
TL;DR: It is concluded that in a Rec(+) strain, the recA(+) product acts to inhibit DNA breakdown determined by the recC(+) and recB(+) products.
Abstract: Strains of Escherichia coli have been made carrying lesions in more than one gene determining recombination. The following genotypes were constructed and verified: recC22 recB21 recA(+), recC22 recB21 recA13, recC22 recB(+)recA13, and recC(+)recB21 recA13. All multiple rec(-) strains carrying recA13 were similar to AB2463, which carries recA13 alone, in their UV sensitivities, recombination deficiencies, and inabilities to induce lambda phage in a lysogen. However, whereas AB2463 shows a high rate of ultraviolet (UV)-induced deoxyribonucleic acid (DNA) breakdown, the multiple rec(-) strains showed the low level characteristic of strains carrying recC22 or recB21 alone. The strain carrying both recC22 and recB21 was similar in all properties to the single mutants, suggesting that both gene products act in the same part of the recombination and UV repair pathways. It is concluded that in a Rec(+) strain, the recA(+) product acts to inhibit DNA breakdown determined by the recC(+) and recB(+) products.

276 citations


Journal ArticleDOI
TL;DR: An enzyme present in Escherichia coli which catalyzes the phosphorylation of histone by ATP has been found to be stimulated by adenosine 3',5'-monophosphate (cyclic AMP).

249 citations


Journal ArticleDOI
TL;DR: The experiments described in this paper were undertaken with a view to detecting and characterizing a toxin which may be present in enteropathogenic E. coli and absent from nonenteropathogenic ones.
Abstract: The mechanism by which Escherichia coli causes diarrhea in pigs has been the subject of much research and speculation. Thomlinson and Buxton [1, 2] and Thomlinson [3] reported experimental evidence from which they concluded that diarrhea was a manifestation of an anaphylactic reaction in hypersensitive pigs. They suggested that the reaction was triggered by the absorption of bacterial polysaccharide during excessive proliferation of certain types of E. coli in the gut. However, the validity of this hypothesis has been challenged [4-6]. Stevens [7] advanced the hypothesis that diarrhea was due to "toxic effects of E. coli,'" and Gyles [8] suggested that the toxic product responsible for diarrhea was not likely to be endotoxin. The experiments described in this paper were undertaken with a view to detecting and characterizing a toxin which may be present in enteropathogenic E. coli and absent from nonenteropathogenic ones. The similarities between coliform diarrhea of swine and choleraic diarrhea of man were borne

Journal ArticleDOI
20 Dec 1969-Nature
TL;DR: The mutation affecting DNA polymerase activity in the mutant strain isolated by De Lucia and Cairns is located between metE and rha, at approximately 75 minutes on the Escherichia coli chromosome.
Abstract: The mutation affecting DNA polymerase activity in the mutant strain isolated by De Lucia and Cairns is located between metE and rha, at approximately 75 minutes on the Escherichia coli chromosome. The mutation is recessive to the wild-type gene in partial diploids. It is an amber nonsense mutation which responds to the suppressors Sul+, Sull+ and Sulll+. Strains carrying the mutation are not deficient in carrying out genetic recombination.

Journal ArticleDOI
TL;DR: The results indicate that this galactokinase consists of one polypeptide chain containing 368 residues, and hence that its structural gene contains about 1100 base pairs.

Journal ArticleDOI
TL;DR: It is concluded that cyclic AMP is necessary for the normal utilization of a number of carbon sources by E. coli, because it is required for the synthesis of enzymes involved in their metabolism.

Journal ArticleDOI
TL;DR: Antibiotic resistance was transferred to the resident Escherichia coli in the alimentary tract of a human being from cultures of E. coli of animal and human origin taken in large doses by mouth.

Journal ArticleDOI
TL;DR: The rec mutations carried by 20 strains of Escherichia coli K-12 which are defective in genetic recombination and sensitive to ultraviolet light and X rays, and whose lambda lysogens show spontaneous phage production, have been mapped near thyA.
Abstract: The rec mutations carried by 20 strains of Escherichia coli K-12 which are defective in genetic recombination and sensitive to ultraviolet light and X rays, and whose lambda lysogens show spontaneous phage production, have been mapped near thyA. In 15 of the strains, the rec mutation fails to complement recB21 but complements rec-22. The other five strains carry a rec mutation which complements recB21 but not rec-22. These mutations map closer to thyA than those which fail to complement recB21. They therefore appear to be defective in a different recombination gene, denoted recC. The order of recB and recC on the linkage map of E. coli K-12 is thyA-recC-recB-argA.

Journal ArticleDOI
TL;DR: A temperature-sensitive mutant of E. coli, which cannot synthesize DNA at high temperature but can continue cell division, shows a difference in a membrane protein fraction at highTemperature by gel electrophoresis, which may link DNA replication and cell division through the membrane.
Abstract: A temperature-sensitive mutant of E. coli, which cannot synthesize DNA at high temperature but can continue cell division, shows a difference in a membrane protein fraction at high temperature by gel electrophoresis. This mutation of a bacterial membrane protein is unique. The protein may link DNA replication and cell division through the membrane.

Journal ArticleDOI
TL;DR: The authors speculate that E. coli cells die off in the course of starvation not because some unique structure is destroyed, but owing to the fact that the activity of enzymes and ribosomes gradually declines, and the synthetic activity of the cell drops down abruptly and irreversibly.
Abstract: The work is concerned with studying the breakdown of proteins and RNA when a polyauxotrophic Escherichia coli strain is incubated in a salt solution without amino acids, phosphorus, nitrogen and glucose at 43 degrees C as well as the ability of starving bacterial cells to recommence protein and RNA synthesis (also in the course of phage T4 infection) and to reproduce bacteriophages T4, lambda and MS2. Within the first two hours of the incubation, 12% of proteins and 40% of RNA break down to acid-soluble fragments. Then protein degradation stops while RNA decomposition goes on, but at a lower rate. Within 4-6 h of starvation, the rate of protein and RNA synthesis drops down 4-5 times and the survival rate equals 40-60% when the cells are transferred onto a complete medium. The quantitative characteristics of phages T4, lambda and MS2 reproduction fall down in prestarved cells. The authors speculate that E. coli cells die off in the course of starvation not because some unique structure is destroyed, but owing to the fact that the activity of enzymes and ribosomes gradually declines. As a result, the synthetic activity of the cell drops down abruptly and irreversibly because the enzymes are inactivated and RNA breaks down, which eventually causes cell death.

Journal ArticleDOI
TL;DR: It is proposed that the intracellular level of cyclic AMP regulates the rate of synthesis of many inducible enzymes in E. coli and other microorganisms and that glucose lowers the rate

Journal ArticleDOI
TL;DR: A DNase which requires ATP for its function was purified from E. coli and some of the characteristics of the purified enzyme were studied and the possible role of the enzyme in genetic recombination is discussed.
Abstract: A DNase which requires ATP for its function was purified from E. coli and some of the characteristics of the purified enzyme were studied. This enzyme activity could not be detected in certain (recB and recC) recombination deficient mutant strains. The possible role of the enzyme in genetic recombination is discussed.

Journal ArticleDOI
TL;DR: R-factor strains which are streptomycin-resistant and spectinomycin -sensitive have been found to inactivate strePTomycin by a new mechanism that involves phosphorylated 3'-OH group of the 2-deoxy-2-methylamino-l-glucopyranosyl moiety.
Abstract: R-factor strains which are streptomycin-resistant and spectinomycin-sensitive have been found to inactivate streptomycin by a new mechanism. The 3′-OH group of the 2-deoxy-2-methylamino-l-glucopyranosyl moiety is phosphorylated.

Journal ArticleDOI
TL;DR: An F-thr-ara ‡ episome has been inserted into the Escherichia coli chromosome at the T1 locus near the attachment site for bacteriophage φ 80 and a φ80dara transducing phage was isolated from a strain carrying such an insertion.

Journal ArticleDOI
05 Dec 1969-Science
TL;DR: The 30S ribosomal proteins of strains of Escherichia coli sensitive to and dependent on streptomycin are compared and a single protein is identified that is functionally altered in the ribosomes dependent on Streptomytin.
Abstract: We have compared the 30S ribosomal proteins of strains of Escherichia coli sensitive to and dependent on streptomycin and identified a single protein that is functionally altered in the ribosomes dependent on streptomycin. This protein (30S-15) is the same protein that is functionally altered in ribosomes resistant to streptomycin.

Journal ArticleDOI
TL;DR: The results support the hypothesis that most UV-induced mutations originate as errors in recombinational repair of single-strand gaps in DNA.
Abstract: Strains having recA and recC mutations were tested for UV mutability. A recA strain is UV-stsable at doses that are demonstrably mutagenic in its Rec+ derivative. Strains of recC genotype are not UV-stable, but produce UV-induced mutations at frequencies significantly lower than those produced at the same doses in Rec+ strains. The results support the hypothesis that most UV-induced mutations originate as errors in recombinational repair of single-strand gaps in DNA.

Journal ArticleDOI
TL;DR: The greater level of survival after irradiation in Rec(+) as compared to Rec(-) bacteria may be due to a recovery mechanism involving the reconstruction of the bacterial chromosome through genetic exchanges which occur between the newly replicated sister duplexes and which effectively circumvent the damaged bases remaining in the DNA.
Abstract: Strains of Escherichia coli that carry the mutation uvrA6 show no measurable excision of pyrimidine dimers and are easily killed by ultraviolet (UV) light, whereas strains that carry recA13 are defective in genetic recombination and are also UV-sensitive. An Hfr strain carrying uvrA6 was crossed with an F− strain carrying recA13. Among the recombinants identified, one carrying uvrA recA proved to be of exceptional sensitivity to UV light. It is estimated from the UV dose (0.2 erg/mm2 at 253.7 nm) required to reduce the number of colony-forming cells by one natural logarithm that about 1.3 pyrimidine dimers were formed in a genome of 5 × 106 base pairs for each lethal event. This double mutant is 40 times more UV-sensitive than the excision-defective strain carrying uvrA6. The replication of one pyrimidine dimer is generally a lethal event in strains carrying recA13. Spontaneous breakdown and UV-induced breakdown of the deoxyribonucleic acid (DNA) of cells of the various genotypes were estimated by growing the cells in medium containing 3H-thymidine and measuring both acid-precipitable and acid-soluble radioactivity. The UV-induced degradation in strains with recA13 did not require the uvr+ genes and hence appears to depend upon a mechanism other than dimer excision. The greater level of survival after irradiation in Rec+ as compared to Rec− bacteria may be due to a recovery mechanism involving the reconstruction of the bacterial chromosome through genetic exchanges which occur between the newly replicated sister duplexes and which effectively circumvent the damaged bases remaining in the DNA.

13 Dec 1969
TL;DR: The complete amino acid sequence of the acyl carrier protein (ACP) from Escherichia coli has been established and contains 77 residues with NH2- terminal serine and COOH-terminal alanine.
Abstract: Abstract The complete amino acid sequence of the acyl carrier protein (ACP) from Escherichia coli has been established. It contains 77 residues with NH2-terminal serine and COOH-terminal alanine. The pantotheine prosthetic group of ACP is attached covalently to the hydroxyl group of serine at residue 36, which is 1 of 3 seryl residues in the molecule. This unique sequence was deduced by sequence analysis of the tryptic, peptic, and thermolysin peptides isolated from enzymic hydrolysates of ACP as described earlier. Important overlaps in sequence were also obtained by partial sequence analysis of one of the two unique peptides formed on cleavage of ACP with CNBr, and by sequence analysis of a single tryptic peptide isolated from tryptic digests of ACP modified at its single arginyl residue with 1,2-cyclohexanedione.

Journal ArticleDOI
04 Jul 1969-Science
TL;DR: Reconstitution of active particles in the presence of isolated split proteins allowed the identification of the single split protein responsible for spectinomycin sensitivity.
Abstract: Reconstitution of 30S ribosomal particles from 16S ribosomal RNA and total proteins, or from core proteins and split proteins obtained from the ribosomes of strains of Escherichia coli sensitive to and resistant to spectinomycin, shows that the split protein fraction determines the response of polypeptide synthesis in virto to spectinomycin. Reconstitution of active particles in the presence of isolated split proteins allowed the identification of the single split protein responsible for spectinomycin sensitivity.

Journal ArticleDOI
TL;DR: Mutants with altered glycogen metabolism may be useful in investigating the physiological function of bacterial glycogen and in determining the physiological significance of the allosteric regulation of the pyrophosphorylase.
Abstract: Synthesis of the a-1,4 glucosidic linkages in bacterial glycogen is catalyzed by two enzymes (5, 8). The first enzyme, adenosine diphosphate (ADP)-glucose pyrophosphorylase, catalyzes the synthesis of ADP-glucose from adenosine triphosphate (ATP) and glucose-l-phosphate. The second enzyme, ADP-glucose: a-i ,4 glucan, synthesize glycogen. A preliminary description of some of these mutants is presented. Mutants with altered glycogen metabolism may be useful in investigating the physiological function of bacterial glycogen and in determining the physiological significance of the allosteric regulation of the pyrophosphorylase.


Journal ArticleDOI
TL;DR: An endonuclease activity was purified about 150-fold from T4 phage-infected Escherichia coli B and this enzyme has been named T4 end onuclease IV and introduces breaks preferentially into single stranded DNA.