Showing papers on "Escherichia coli published in 1971"

Pathogenesis of Escherichia coli diarrhea.

Abstract: Two Escherichia coli strains isolated in Vietnam from American soldiers with diarrhea and acute "colitis" were examined for virulence in both in vitro and in vivo experimental models. Their biologic properties were compared with those of an enterotoxin-producing Esch. coli strain implicated in disease of swine as well as with those of four other Esch. coli and a virulent shigella strain. The two Vietnam strains produced an enterotoxin in a rabbit ileal-loop model and in volunteers caused a diarrheal syndrome resembling that of cholera. Two nontoxigenic Esch. coli strains gave evidence of penetrating epithelial cells in laboratory models and caused a shigella-like illness in man characterized by dysentery, tenesmus, urgency, hyperpyrexia and hypotension with systemic toxemia. Thus, strains of Esch. coli can cause disease in man by at least two mechanisms: elaboration of a cholera-like enterotoxin; and shigella-like intestinal epithelial penetration.

Properties of an R Factor from Pseudomonas aeruginosa

Abstract: An R factor from Pseudomonas aeruginosa, which confers resistance to penicillins, kanamycin, and tetracycline, was studied in Escherichia coli K-12. The R factor could coexist with F-like or I-like plasmids and therefore constituted a novel compatibility group. The R factor was transferable from E. coli to bacterial genera outside the Enterobacteriaceae (Pseudomonas and members of the Rhizobiaceae) to which transfer of F-like and I-like plasmids could not be demonstrated.

Chromosome Replication and the Division Cycle of Escherichia coli B/r

Abstract: The average amount of deoxyribonucleic acid (DNA) per cell was measured in steady-state cultures of Escherichia coli B/r grown at 37 C in glucose-limited chemostats or in batch cultures in the exponential growth phase as maintained with one of several carbon sources. Within experimental errors, DNA content was dependent only on growth rate and independent of the type of culture, the carbon source, or the addition of growth factors. The amount of DNA per cell increased continuously with growth rate over the range of 0.02 to 3 divisions per hour. The data over the entire range of growth rates are in agreement with a constant time for a single replication point to traverse the entire genome, 47 min, and with cell division following 25 min after termination of replication. The measured amount of DNA per genome was 4.2 x 10(-15) g (or 2.5 x 10(9) daltons).

Observations On The Pathogenic Properties Of The K88, Hly And Ent Plasmids Of Escherichia Coli With Particular Reference To Porcine Diarrhoea

Abstract: Summary Strains of Escherichia coli containing different combinations of the transmissible plasmids governing production of α-haemolysin (Hly), enterotoxin (Ent) and K88 antigen (K88) were prepared by the selective addition or removal of these plasmids and tested for ability to produce diarrhoea when given orally to naturally reared piglets and to recently weaned pigs. The removal of the K88 plasmid from an O141:K85ab,88ab strain was accompanied by the loss of its diarrhoea-producing capacity. It was restored by introducing a K88 plasmid from another strain of E. coli. The removal of the Hly plasmid had no observable effect. Neither did its removal from another wild enteropathogenic strain of antigenic formula O141:K85ac; the Hly- form of this strain, like the Hly+ form, produced oedema disease in addition to diarrhoea. As a consequence of receiving an Ent plasmid, a non-haemolytic O8:K40, 88ab:H9 strain produced diarrhoea more frequently and more severely in piglets than hitherto; after the removal of the K88 plasmid it became non-enteropathogenic. A non-pathogenic O9:K36:H19 strain was rendered enteropathogenic by the introduction of plasmids. The K88+ Ent+ form produced moderately severe diarrhoea in piglets. A smaller proportion of those given the K88+ Ent- form developed a milder diarrhoea. The K88- Ent+ and the K88- Ent- forms had no observable ill-effect. Bacteriological examinations on the animals given the different forms of the O141:K85ab,88ab, the O8:K40,88ab:H9 and the O9:K36:H19 strains revealed that it was the K88 antigen that enabled the organisms to proliferate high up in the small intestine, an essential prerequisite in the pathogenesis of E. coli diarrhoea. The Ent plasmid appeared to play no part in this proliferation, only in the diarrhoea that followed. The introduction of Hly into strains of E. coli was usually accompanied by an increase in virulence for mice challenged intraperitoneally, the extent of the increase varying according to the particular Hly plasmid introduced. Virulence was not related directly to haemolytic activity. K88+ forms of strains of E. coli were less virulent for mice on intraperitoneal injection than were the corresponding K88- forms. So were K88+ forms of Salmonella typhimurium and S. choleraesuis after intraperitoneal and oral infection; the K88+ organisms were less able to survive in the alimentary tract and in the tissues than were the K88- ones. A K88+ form of S. choleraesuis was also less virulent for pigs than was the corresponding K88- form.

Potassium Transport Loci in Escherichia coli K-12

Abstract: Mutants of Escherichia coli K-12 requiring considerably elevated concentrations of potassium for growth are readily obtained as double mutants combining a kdp mutation with a mutation in one or more of five other loci. These loci are referred to as trk, for transport of K, because these mutations result in alterations in K transport. The kdp mutation is essential in the isolation and identification of this type of mutant; in a Kdp(+) strain, the presence of a trk mutation does not prevent growth of the strain in media containing very low concentrations of K. The trk loci are widely scattered over the E. coli chromosome; none of them is very near any other trk locus or near the kdp genes.

Beginning a Genetic Analysis ofConjugational Transfer Determined bytheFFactorin Escherichia coli byIsolation andCharacterization ofTransfer-Deficie nt Mutants

Abstract: Eighty-four transfer-deficient mutants of Flac have been isolated; 27 of these bear amber mutations and 1 mutant is temperature-sensitive. All the mutants transfer between 10−2 and <10−5% as well as wild-type Flac, all are curable by acridine orange treatment, and all are resistant to the female-specific phage φII. Some of the mutants are partially sensitive to female-specific phage tau. Sixty-three of the mutants are resistant to the male-specific phages f1, f2, and Qβ; 15 are resistant only to f2; and 6 are sensitive to all three male-specific phages. Most of the mutants are still poor recipients in conjugation, but four of the mutants resistant to f1, f2, and Qβ have become good recipients. Those mutants resistant to all three male-specific phages do not seem to make F-pili.

Oxidative phosphorylation in Escherichia coli K 12. Mutations affecting magnesium ion- or calcium ion-stimulated adenosine triphosphatase

Abstract: 1. Two mutants of Escherichia coli K 12 were isolated which, although able to grow on glucose, are unable to grow with succinate or d-lactate as the sole source of carbon. 2. Genetic mapping of these mutants showed that they both contain a mutation in a gene (designated uncA) mapping at about minute 73.5 on the E. coli chromosome. 3. The uncA− alleles were transferred by bacteriophage-mediated transduction into another strain of E. coli and the transductants compared with the parent strain to determine the nature of the biochemical lesion in the mutants. 4. The mutants gave low aerobic growth yields when grown on limiting concentrations of glucose, but oxidase activities in membranes from both the mutants and the normal strain were similar. 5. Measurement of P/O ratios with d-lactate as substrate indicated that a mutation in the uncA gene causes uncoupling of phosphorylation associated with electron transport. 6. Determination of the Mg2+,Ca2+-stimulated adenosine triphosphatase activities in the mutant and normal strains indicated that the uncA gene is probably the structural gene for Mg2+,Ca2+-stimulated adenosine triphosphatase. 7. Mg2+,Ca2+-stimulated adenosine triphosphatase therefore appears to be essential for oxidative phosphorylation in E. coli.

Temperature control of phospholipid biosynthesis in Escherichia coli.

Abstract: The higher the growth temperature of Escherichia coli cultures the greater is the proportion of saturated fatty acids in the bacterial phospholipids. When fatty acids are exogenously supplied to E. coli, higher growth temperatures will likewise increase the relative incorporation of saturated fatty acids into phospholipids. One of the steps in the utilization of fatty acids for phospholipid biosynthesis is, therefore, temperature-controlled. The temperature effect observed in vivo with mixtures of (3)H-oleate and (14)C-palmitate is demonstrable in vitro by using mixtures of the coenzyme A derivative of these fatty acids for the acylation of alpha-glycerol phosphate to lysophosphatidic and phosphatidic acids. In E. coli extracts, the relative rates of transacylation of palmityl and oleyl coenzyme A vary as a function of incubation temperature in a manner which mimics the temperature control observed in vivo. The phosphatidic acid synthesized in vitro shows a striking enrichment of oleate at the beta position analogous to the positional specificity observed in phospholipids synthesized in vivo.

Role of Lipopolysaccharides in Antibiotic Resistance and Bacteriophage Adsorption of Escherichia coli K-12

Abstract: Novobiocin-supersensitive (NS) mutants which could not grow on plates containing 40 μg or less of novobiocin per ml were isolated from Escherichia coli strain JE1011 (derived from E. coli K-12). Most of these NS mutants were found to have incomplete lipopolysaccharides (LPS), and they lack phosphate diester bridges in their backbone structure, with or without total loss of heptose, to which the phosphate diester is linked, and consequently lack external outer-core oligosaccharides. The phosphate diester bridges in the LPS backbone are apparently very important in forming a cell surface structure resistant to the penetration of antibiotics such as novobiocin, spiramycin, and actinomycin D. NS mutants, with incomplete LPS, lacking phosphates in their backbone structure were found to be resistant to phage T4, and those which also lacked heptose were resistant to phages T4 and T7. In contrast to the generally accepted idea that resistances to phages T3, T4, and T7 are linked genetically, no NS mutant was found to be resistant to T3. The possible structures of the receptors for T4 and T7 are discussed. The positions of novobiocin-supersensitive genes on the chromosome of several of the NS mutants defective in LPS were mapped. The genes were designated lpcA (between ara and lac) and lpcB (between 55 min and 60 min). The latter seemed to be a group of several related genes.

Acute undifferentiated human diarrhea in the tropics: I. Alterations in intestinal microflora

Abstract: The microflora of the small and large intestine was determined in 17 adults with acute undifferentiated diarrhea in Calcutta, India. On the basis of bacteriologic findings, the patients could be divided into two groups: those with a predominant flora of Escherichia coli (eight patients) and those with a mixed coliform flora (nine patients). In the former group, E. coli were distributed throughout the small and large bowel. Broth filtrates of these isolates contained an enterotoxin which caused fluid accumulation in the rabbit intestinal loop model. Toxigenic E. coli were cleared rapidly from the small bowel during the acute period; some patients only had the “hot” strains in their fecal effluent. During convalescence, the serotypes of E. coli changed and the new strains did not elaborate enterotoxin. Only one of the eight patients had a serotype previously associated with diarrhea. Acute undifferentiated diarrhea in the remaining cases was apparently caused by untypable E. coli or by typable strains not generally considered pathogenic. Small bowel and fecal cultures from the mixed flora group revealed a heterogeneous mixture of Gram-negative enteric bacilli and a distinct pattern could not be discerned. Further study will be needed to elucidate the cause of diarrhea in these cases.

Change in Methylation of 16S Ribosomal RNA Associated with Mutation to Kasugamycin Resistance in Escherichia coli

Abstract: Resistance to a drug acting on the 30S ribosomal subunit is attributed to non-methylation of 16S RNA.

Evidence for the Bidirectional Replication of the Escherichia coli Chromosome

Abstract: Experiments with transducing phage indicate that the circular chromosome of Escherichia coli is replicated in both directions from a fixed origin.

The presence and possible role of zinc in RNA polymerase obtained from Escherichia coli.

Abstract: Highly purified preparations of the DNA-dependent RNA polymerase obtained from Escherichia coli contain about 2 g-atoms of tightly bound zinc per mol (molecular weight 370,000) of enzyme. When the purified enzyme is fractionated on Sephadex G-150 or G-200, correlation is observed between the zinc and enzymic activity. Although some of the preparations examined also contain iron, copper, and magnesium, the content of these metal ions show no consistent correlation with RNA polymerase activity. Initiation of RNA synthesis is specifically inhibited by 1,10-phenanthroline. Less-effective inhibition is observed for other chelating agents or for a nonchelating phenanthroline analog. The analog also exhibits a pattern of inhibition differing from that characteristic of 1,10-phenanthroline. Binding of purine nucleoside triphosphates at the lower-affinity (Kd = 0.15 mM) site may also be prevented by the addition of 1,10-phenanthroline. One or both of the bound zinc atoms may, therefore, participate in the initiation of RNA synthesis.

Escherichia coli Mutants Blocked in Lambda DNA Synthesis

Abstract: Both phage and bacterial genes are essential for replication of phage λ DNA. Lambda genes O and P are essential for phage DNA replication; mutants defective in either gene are able to replicate less than one round of DNA (Joyner et al., 1966; Ogawa and Tomizawa, 1968). It has been suggested that genes O and P code for an endonucleolytic activity that acts on λ DNA (Shuster and Weissbach, 1969; E. Jordan, personal communication). It is quite clear that λ replication requires in addition some host DNA synthesis functions, since λ is unable to grow in certain Escherichia coli mutants containing temperature-sensitive defects in DNA synthesis (Hirota et al., 1968; Kohiyama, 1968). In particular, Fangman and Feiss (1969) have reported that λ is unable to replicate at high temperature in a temperature-sensitive mutant of E. coli, FA22, which is defective in host DNA synthesis at 39°C. Here we report the isolation and preliminary characterization of a class of E. coli mutants, called groP − , which are unable to propagate lambdoid phages. Evidence is presented (1) that the block in phage λ development is due to inability of the gene P product to function, and (2) that the groP − bacteria are themselves conditionally defective in DNA synthesis. These results suggest that there is a functional association between the gene P product of phage λ and the host DNA synthesis system. RESULTS AND DISCUSSION Growth of lambdoid phages in bacterial mutants Bacterial mutants ( groP − ) unable to support growth of λ and 434 were...

Inactivation of Escherichia coli, F' episomes at transfer, and bacteriophage lambda by psoralen plus 360-nm light: significance of deoxyribonucleic acid cross-links.

Abstract: We have investigated some biological consequences of light-induced psoralen-deoxyribonucleic acid (DNA) adducts and find that for several Escherichia coli functions (killing of strain AB2480 recA13 uvrA6, inactivation of phage lambda plaque-forming ability in wild type and uvrA6 hosts, loss of ability to transmit intact Flac+ episomes), a light exposure sufficient for production of a single cross-link per DNA molecule correlates well with the biological consequence. Although one cross-link per genome is apparently lethal to recA13 uvr− strains, mutants carrying the recA13 or uvrA6 markers survive light exposures producing 6.7 and 16 cross-links per genome, respectively, and wild-type cells recover from 65 psoralen cross-links. Evidently, the excision and recombinational repair systems complement one another in reconstructing an intact genome from cellular DNA containing psoralen photoproducts. The above bacterial and phage strains, in which DNA repair processes are minimized, are also extremely sensitive to pyrimidine dimer-forming 254-nm UV light (without psoralen), and were expected to respond similarly to formation of psoralen-pyrimidine base monoadducts in their DNA. Since the biological inactivation by psoralen correlates well with cross-link formation, we suggest that the sensitizing action of this drug primarily derives from its ability to form DNA cross-links.

Biochemical Bases for the Antimetabolite Action of l-Serine Hydroxamate

Abstract: The amino acid analogue l-serine hydroxamate, which is bacteriostatic for Escherichia coli, has been shown to inhibit protein synthesis. The antimetabolite is a competitive inhibitor of seryl-transfer ribonucleic acid (tRNA) synthetase with a K(i) value of 30 mum. Mutants resistant to l-serine hydroxamate have been selected, and three were shown to have seryl-tRNA synthetases with increased K(i) values. One mutant contains a 3-phosphoglycerate dehydrogenase which is insensitive to inhibition by l-serine.

The virulence for mice of strains of Escherichia coli related to the effects of K antigens on their resistance to phagocytosis and killing by complement.

Abstract: Strains of Escherichia coli with sufficient K antigen to resist killing by complement were poorly phagocytosed when injected intravenously into mice. Phagocytosis was markedly increased by anti-OK but not by anti-O sera. In contrast anti-K sera had little or no effect on the bactericidal reaction. This was not because K antigenic sites were scarce but may have been because their position was such that complement was activated at a distance from its substrate. Red cells coated with K antigen were poorly lysed by complement and anti-K serum, suggesting that the K antibody did not activate complement very effectively although again the sites may have been too superficial. The effect of K antigens on phagocytosis and complement killing or lysis could all be explained by their ability to impair protein binding. Strains of E. coli rich in K antigen were resistant to phagocytosis and complement killing and were virulent for mice on intracerebral injection. The significance of K antigens in animal and human infections is discussed.

Polarity and enzyme functions in mutants of the first three genes of the tryptophan operon of Escherichia coli.

Abstract: N operons which are believed to be transcribed into polycistronic messenger I RNA molecules, some revertible mutations result in a lowered rate of synthesis of enzymes specified by genes operator-distal to the mutated gene. This phenomenon, termed polarity (FRANKLIN and LURIA 1961 ; JACOB and MONOD 1961 ) , has been studied in several organisms and a variety of explanations have been proposed for the observed effect on enzyme levels. Mutational changes which cause polarity are now known to have in common the introduction of a polypeptide chain-termination codon within a structural gene of an operon (NEWTON et al. 1965; WHITFIELD, MARTIN and AMES 1966; YANOFSKY and ITO 1966). Mutations of the missense type, resulting in amino acid substitutions, do not cause polarity. In the present study mutants of the first three genes of the tryptophan operon of Escherichia coli were characterized. The properties of the mutants and their respective altered proteins or protein fragments revealed interesting features of the corresponding wild-type proteins. Many of the mutants exhibited polarity and were employed in determinations of the shape of the polarity gradient for their respective genes. Additionally, antipolarity ( ITO and CRAWFORD 1965; YANOFSKY and ITO 1967), an effect on expression of the gene immediately preceding a gene with a chain termination mutation, was examined in strong polar mutants of several genes of the operon.

Correlation of 30S ribosomal proteins of Escherichia coli isolated in different laboratories.

Abstract: Ribosomal proteins isolated from 30S subunits ofE. coli in four laboratories have been correlated by using two-dimensional gel electrophoresis, immunological techniques, amino acid compositions and molecular weights. The results are given in the Table. A common nomenclature for naming 30 S ribosomal proteins and their genetic loci is proposed.

Dark Repair of Ultraviolet-Irradiated Deoxyribonucleic Acid by Bacteriophage T4: Purification and Characterization of a Dimer-Specific Phage-Induced Endonuclease

Abstract: The purification and properties of an ultraviolet (UV) repair endonuclease are described. The enzyme is induced by infection of cells of Escherichia coli with phage T4 and is missing from extracts of cells infected with the UV-sensitive and excision-defective mutant T4V(1). The enzyme attacks UV-irradiated deoxyribonucleic acid (DNA) containing either hydroxymethylcytosine or cytosine, but does not affect native DNA. The specific substrate in UV-irradiated DNA appears to be pyrimidine dimer sites. The purified enzyme alone does not excise pyrimidine dimers from UV-irradiated DNA. However, dimer excision does occur in the presence of the purified endonuclease plus crude extract of cells infected with the mutant T4V(1).

Genetic Analysis of Diaminopimelic Acid- and Lysine-Requiring Mutants of Escherichia coli

Abstract: Several diaminopimelic acid (DAP)- and lysine-requiring mutants of Escherichia coli were isolated and studied by genetic, physiological, and biochemical means. The genes concerned with DAP-lysine synthesis map at several different sites on the E. coli chromosome and, therefore, do not constitute a single operon. Three separate loci affecting DAP synthesis are located in the 0 to 2.5 min region of the genetic map. The order of the loci in this region is thr-dapB-pyrA-ara-leu-pan-dapC-tonA-dapD. Two additional DAP genes map in the region between min 47 and 48, with the gene order being gua-dapA-dapE-ctr. The lys locus at min 55 determines the synthesis of the enzyme DAP decarboxylase, which catalyzes the conversion of DAP into lysine. The order of the genes in this region is serA-lysA-thyA.

Involvement of recombination genes in growth and viability of Escherichia coli K-12.

Abstract: We have studied the growth properties of 17 isogenic strains of Escherichia coli K-12 differing only in the recA, recB, recC, and sbcA alleles. We have observed the following. (i) All recombination deficient strains have decreased growth rates and decreased viabilities compared with recombination proficient strains. The large populations of nonviable cells in Rec(-) cultures may arise by spontaneous lethal sectoring (9). (ii) A recA mutant strain which is entirely recombination deficient and which shows high ultraviolet sensitivity and "reckless" deoxyribonucleic acid (DNA) breakdown has approximately the same growth rate and twice the viability as recB and recC mutant strains which have residual recombination proficiency, moderate ultraviolet sensitivity, and "cautious" DNA breakdown. (iii) Indirectly suppressed (sbcA(-)) recombination proficient (Rec(+)) revertants of recB and recC mutant strains have approximately normal growth rates and are three times as viable as their Rec(-) ancestors (but not as viable as rec(+) cells). We suggest the following hypothesis to account for the low viability of Rec(-)E. coli. Single-strand breaks in the DNA duplex, necessary for normal bacterial growth, may be repaired in a Rec(+) cell. Failure of Rec(-) cells to repair this normal DNA damage may lead to the observed loss of viability.