PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ESCHERICHIA INFECTIONS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1973

Bacteriophage tail components. IV. Pteroyl polyglutamate synthesis in T4D-infected Escherichia coli B.

The nature of pteroyl polyglutamates in uninfected and T4D bacteriophage-infected Escherichia coli B has been examined. (3)H-p-aminobenzoic acid has been used to label the folate compounds and gel permeation chromatography on glass beads to separate the folate compound by molecular size. It has been found that, although the major folate compound in uninfected bacteria is pteroyl triglutamate, E. coli B cells also contain folate compounds having as many as six glutamate residues. Infection with T4D stimulated the addition of glutamate residues to the lower-molecular-weight host pteroyl compounds, resulting in the conversion of the host compounds into the hexaglutamate form. This viral-induced conversion is chloramphenicol sensitive and appears to be due to a late phage gene product. The phage gene responsible for this conversion has not been identified. In cells infected with a T4D mutant defective in gene 28, there was an apparent production of the large pteroyl polyglutamates equivalent in size to pte(glu)(9-12). These high-molecular-weight forms were converted into pte(glu)(6) by incubation with bacterial extracts made after infection with T4D 28(+). Apparently, the product of T4D gene 28(+) is capable of specifically cleaving the high-molecular-weight polyglutamates to the form necessary for phage tail assembly.

Aminobenzoates↗
PubMed1975

Phospholipase activity in bacteriophage-infected Escherichia. II. Activation of phospholipase by T4 ghost infection.

The release of free fatty acids from the phospholipids of Escherichia coli is initiated immediately after the attachment of T4 ghosts. A similar accumulation of free fatty acids is observed if the cells are infected with T4 phage in the presence of chloramphenicol or puromycin. An early accumulation of free fatty acids, however, is not observed in T4 infections in which chloramphenicol or puromycin are not present, nor does it occur if the E. coli are infected with T4 phage before ghost infection, suggesting that phage products can prevent the phospholipid deacylation. If E. coli is infected with T4 ghosts before T4 phage infection, the accumulation of free fatty acids is not suppressed. When phospholipase-deficient E, coli are infected with T4 ghosts the appearance of free fatty acids is not observed, suggesting that T4 ghost attachment can activate the phospholipase of wild-type E. coli. Although the formation of free fatty acid apparently is a consequence of activation of the detergent-resistant phospholipase of the outer membrane, it is not observed in mutants deficient in the detergent-sensitive phospholipase.

Cell Membrane↗
PubMed1976

Fractionation of membrane vesicles from coliphage M13-infected Escherichia coli.

Membrane vesicles were prepared by osmotic lysis of spheroplasts from M13-infected Escherichia coli. Reduced nicotinamide adenine dinucleotide (NADH) oxidase (reduced NAD: oxidoreductase, EC 1.6.99.3) and Mg2+-Ca2+-activated adenosine triphosphatase (ATP phosphohydrolase, EC 3.6.1.3), which are normally localized to the inner surface of the cytoplasmic membrane, were 50% acceesible to their polar substrates in these vesicles. The major coat protein of coliphage M13 is also bound to the cytoplasmic membrane (prior to phage assembly) but with its antigenic sites exposed to the exterior of the cell. Antibody to M13 coat protein was used to fractionate membrane vesicles. Neither agglutinated nor unagglutinated vesicles had altered NADH oxidase and adenosine triphosphatase specific activities. This is inconsistent with such vesicles being a mixture of correctly oriented and completely inverted membrane sacs and suggests that NADH oxidase, adenosine triphosphatase, M13 coat protein, or all three proteins rearrange during vesicle preparation.

Adenosine Triphosphatases↗
PubMed1969

Host-virus interaction in ribonucleic acid bacteriophage-infected Escherichia coli. I. Location of "late" MS2-specific ribonucleic acid synthesis.

When actinomycin-treated, MS2-infected Escherichia coli are labeled during a brief period later than 16 min after infection, the newly synthesized MS2 ribonucleic acid (RNA) appears first in the 30,000 x g sediment, probably bound to fragments of bacterial membranes, since the radioactivity can be released from the sediment with deoxycholate or urea. With longer labeling times, radioactivity also appears in the 30,000 x g supernatant fluid. While on the membrane, the RNA is organized into particles with sedimentation coefficients of 40, 32, and 27S in the presence of low Mg(2+). In the presence of high Mg(+), MS2-specific RNA is found in polyribosomes. These data are interpreted to mean that MS2-specific RNA is synthesized and organized into larger structures on membrane. More than 8 min of labeling is required before radioactivity is found in the 81S virion which appears in the supernatant fluid.

Bacteriophages↗
PubMed1986

Phage and host genetic determinants of the specific anticodon loop cleavages in bacteriophage T4-infected Escherichia coli CTr5X.

Anticodon loop cleavages of two host tRNA species occur in bacteriophage T4-infected Escherichia coli CTr5X, a host strain restricting phage mutants deficient in polynucleotide kinase (pnk) or RNA ligase (rli). The cleavage products accumulate with the mutants but are further processed in wt infection through polynucleotide kinase and RNA ligase reactions. Inactivating mutations in stp suppress pnk- or rli- mutations in E. coli CTr5X and, as shown here, also abolish the anticodon nuclease, implicating the stp product with this activity. We show also that there exist other suppressing mutations of a pnk- (pseT2) mutation that appear not to affect the anticodon nuclease and are not in stp. It has been shown that a single locus in E. coli CTr5X, termed prr, determines the restriction of pnk- or rli- mutants. A transductant carrying prr featured upon infection the anticodon nuclease reaction products, suggesting that prr determines the specific manifestation of this activity. However, prr does not encode the tRNA species that are vulnerable to the anticodon nuclease.

Anticodon↗
PubMed1989

[The characteristics of acute enterocolitis and Escherichia infections in the Ukrainian SSR].

A nosogeographic study in the Ukrainian SSR revealed 3 zones of gastroenterocolitis morbidity: low, average and above average. Also cartographically were determined 3 Escherichia infection morbidity zones in children under 1 year of age. Conformity of pathogenic Escherichia serogroups (025, 026, 055, 0119 and others) among most humans, animals and environment suggest circulation of pathogens by the cycle: man (patient, carrier)--environment--animals (birds) and vice versa.

Acute Disease↗
PubMed1975

Poly(A) synthesis in T2L phage-infected Escherichia coli. A combination of polynucleotide phosphorylase and ATPase.

In crude extracts of T2L phage-infected Escherichia coli cells an enzyme activity was found that produced poly(A) from ATP as substrate. Purification of the extract led to the isolation of two enzymes, a polynucleotide phosphorylase and an ATPase. The polynucleotide phosphorylase possessed the same properties as the well-known enzyme from uninfected cells and its molecular weight was about 265 000. The ATPase was purified to over 90% purity; its molecular weight was estimated to be about 165 000 with three subunits of 55 000. The characterization of this enzyme showed that it was different from any ATPase known so far. Mg2+ cannot be replaced by Ca2+, as it can from the membrane-bound ATPases. The only product yielded by the enzyme was ADP; it was very specific for ATP, other ribonucleotide triphosphates being practically unaffected. The rate of ATP splitting was found to be very high, the turnover number being 2.51 X 10(4) min-1 at 37 degrees C. Even at 0 degree C the enzyme was still active. The optimal assay conditions for ATPase turned out to be very similar to those of polynucleotide phosphorylase. Thus the combination of the two enzymes very efficiently produced poly(A) from ATP. In this combination the polynucleotide phosphorylase was the rate-limiting enzyme, since its turnover number was about 40 times lower than that of the ATPase. The evaluation of a variety of properties of the poly(A)-synthesizing constituent found in the crude extracts led us to conclude that this activity arises from the combined action of ATPase and polynucleotide phosphorylase, and is not due to a poly(A) polymerase.

Adenosine Triphosphatases↗
PubMed1968

Control of lysis of T4-infected Escherichia coli.

The lysis of Escherichia coli B/5 infected with T4Dr48 could be delayed by addition of 9-aminoacridine (9AA). Infected cells showed an early period of maximal response followed by a decline in sensitivity. The ultimate rate of lysis was also affected by the dye. Deoxyribonucleic acid (DNA), protein, and lysozyme synthesis began at the normal time in complexes inhibited by 9AA addition. The rates of synthesis of these macromolecules were lower in the presence of the dye, with DNA and lysozyme synthesis being more strongly affected than total protein synthesis. Penicillin-sensitive cell wall synthesis stopped at about 10 min after infection. Inhibition of oxidative metabolism by early potassium cyanide addition prevented lysis in the presence of intracellular lysozyme. The cyanide-sensitive event occurred at about 20 min in normal infections, and between 30 and 40 min in 9AA-inhibited infections. 9AA could alter both the time at which the cyanide-sensitive event occurred and the time of lysis. Addition of chloramphenicol did not prevent lysis once intracellular lysozyme was present. Lysis from without of infected cells consisted of three phases: an initial sensitivity, followed by a short period of resistance, and then a return to sensitivity in normal infections. The demonstration of the late return to sensitivity depended on the presence of intracellular lysozyme, and could be delayed by 9AA addition.

Acridines↗
PubMed1973

Influence of gene 55 on the regulation of synthesis of some early enzymes in bacteriophage T4-infected escherichia coli.

In Escherichia coli B infected with phage T4 with mutations in gene 55 the shut-off of synthesis of two early enzymes was found to be delayed 10 to 15 min as compared to wild-type T4 infection. The kinetics of early enzyme formation was very similar to that obtained after DNA-negative mutant infection. The transcription of gene 1 (one of the genes coded for early enzymes) ceased at 9 to 12 min after infection whether the gene 55 product was active or not, as determined by the time dependence of fluorouracil rescuability of DNA synthesis in cells infected with a gene 1 amber mutant. The synthesis of the major part of the early RNA species, determined by pulse-labeling with uracil-5-(3)H, was furthermore found to be regulated independently of gene 55. An explanation for the extended early enzyme synthesis in DNA-negative and gene 55 mutant infection is offered: translation of early messengers is restricted after about 12 min in wild-type infection, whereas in cells infected with DNA-negative or gene 55 mutants, i.e., the absence of late protein synthesis, early messengers direct the formation of early enzymes for a longer time.

Cell-Free System↗
PubMed1976

Kinetic studies on the reaction catalyzed by polynucleotide kinase from phage T4-infected Escherichia coli.

Kinetic properties of polynucleotide kinase (EC 2.7.1.78) isolated from Escherichia coli cells infected with phage T4 were investigated. The reaction depends on the concentration of MgATP, while free ATP or free Mg2+ have neither inhibitory nor accelerating effect. The initial reaction velocity was plotted against variable concentrations of ATP as the phosphate donor at various fixed concentrations of 5'-hydroxyl-DNA or -oligo(rA) as the phosphate acceptor in the presence or absence of products. The double reciprocal plot analysis of the data suggested that the reaction obeys the random sequential mechanism. Various constants were determined and the reaction mechanism was discussed.

Adenosine Triphosphate↗
PubMed1976

Membrane protein biosynthesis in bacteriophage BF23-infected Escherichia coli.

When Escherichia coli is infected with bacteriophage BF23, two new proteins with molecular weights greater than 10,000, as indicated by polyacrylamide gel electrophoresis, are found associated with the cells' membranes. One of these, found associated with both the inner and outer membrane, has a molecular weight of about 55,000 and is regulated by the A1 gene of this phage, a gene found on the spontaneously injected 8% piece of BF23 DNA, DNA that codes for the synthesis of proteins necessary for the injection of the whole phage genome. The other protein, often undetected in whole membrane preparations, is found exclusively associated with the inner membrane. Evidence indicates that this protein is also regulated by the initially injected 8% piece of the DNA.

Cell Membrane↗
PubMed1981

Dual functions of bacteriophage T4D gene 28 product: structural component of the viral tail baseplate central plug and cleavage enzyme for folyl polyglutamates. II. Folate metabolism and polyglutamate cleavage activity of uninfected and infected Escherichia coli cells and bacteriophage.

We investigated the role of the T4D bacteriophage gene 28 product in folate metabolism in infected Escherichia coli cells by using antifolate drugs and a newly devised assay for folyl polyglutamate cleavage activity. Preincubation of host E. coli cells with various sulfa drugs inhibited phage production by decreasing the burst size when the phage particles produced an altered gene 28 product (i.e., after infection under permissive conditions with T4D 28(ts) or T4D am28). In addition, we found that another folate analog, pyrimethamine, also inhibited T4D 28(ts) production and T4D 28am production, but this analog did not inhibit wild-type T4D production. A temperature-resistant revertant of T4D 28(ts) was not sensitive to either sulfa drugs or pyrimethamine. We developed an assay to measure the enzymatic cleavage of folyl polyglutamates. The high-molecular-weight folyl polyglutamate substrate was isolated from E. coli B cells infected with T4D am28 in the presence of labeled glutamic acid and was characterized as a folate compound containing 12 to 14 labeled glutamate residues. Extracts of uninfected bacteria liberated glutamate residues from this substrate with a pH optimum of 8.4 to 8.5. Extracts of bacteriophage T4D-infected E. coli B cells exhibited an additional new folyl polyglutamate cleavage activity with a pH optimum of about 6.4 to 6.5, which was clearly distinguished from the preexisting activity in the uninfected host cells. This new activity was induced in E. coli B cells by infection with wild-type T4D and T4D amber mutants 29(-), 26(-), 27(-), 51(-), and 10(-), but it was not induced under nonpermissive conditions by T4D am28 or by T4D 28(ts). Mutations in gene 28 affected the properties of the induced cleavage enzyme. Wild-type T4D-induced cleavage activity was not inhibited by pyrimethamine, whereas the T4D 28(ts) activity induced at a permissive temperature was inhibited by this folate analog. Folyl polyglutamate cleavage activity characteristic of the activity induced in host cells by wild-type T4D or by T4D gene 28 mutants was also found in highly purified preparations of these phage ghost particles. The T4D-induced cleavage activity could be inhibited by antiserum prepared against highly purified phage baseplates. We concluded that T4D infection induced the formation of a new folyl polyglutamate cleavage enzyme and that this enzyme was coded for by T4D gene 28. Furthermore, since this gene product was a baseplate tail plug component which had both its antigenic sites and its catalytic sites exposed on the phage particle, it was apparent that this enzyme formed part of the distal surface of the phage baseplate central tail plug.

Carboxypeptidases↗
PubMed1975

Characterization of an inhibitor causing potassium chloride sensitivity of an RNA polymerase from T4 phage-infected Escherichia coli.

The nature of the inhibition by salt (KCl) of DNA-dependent RNA polymerase from T4 phage-infected Escherichia coli (T4 enzyme) was studied using holoenzyme preparations, core enzyme and sigma fractions obtained by phosphocellulose column chromatography, and sigma fractions further purified by gradient centrifugation in the presence and absence of 6 M urea. We showed with holoenzyme preparations that salt inhibits the formation of rifampicin-resistant preinitiation complexes. The inhibition was considerably reduced when a nonionic detergent (particularly of the Triton series) was included in the reaction mixtures. With T4 core enzyme and T4 sigma fractions together with the same fractions from uninfected cells (host enzyme fractions) and different DNA templates, we showed that the T4 sigma fraction plays a role in the salt-sensitive activity with T4 DNA. The salt sensitivity of the T4 sigma fraction was antagonized by Triton; it was not a function of sigma fractions isolated from phage cultures infected in the presence of chloramphenicol. As reported previously (Stevens, A. (1973), Biochem. Biophys. Res. Commun. 54, 488), the T4 sigma fraction inhibited the activity of host sigma when they were present together in reaction mixtures, particularly in the presence of salt. T4 sigma further purified by centrifugation in glycerol gradients had the same properties as the cruder fraction, and the T4-specific polypeptide of mol wt 10000 (Stevens, A. (1972), Proc. Natl. Acad. Sci. U.S.A. 69, 603) was found in the same fractions. If the glycerol gradients contained 6 M urea, the mol wt 10000 polypeptide was separated from the salt-stimulated sigma. Fractions containing the small polypeptide could be added back to produce the salt-inhibitory effects. The inhibitory activity of both the crude sigma fraction and the fractions containing the small polypeptide was inactivated at 65 degrees C. The results suggest that the mol wt 10000 protein is a salt-promoted inhibitor, but the small amounts of it which are present in purified fractions of the T4 enzyme have not yet allowed its isolation in large enough quantities to permit a detailed study of its properties.

Coliphages↗
PubMed1980

DNA-RNA polymerase complexes associated with the membrane from bacteriophage T2- or T4-infected Escherichia coli. I. General properties.

Properties of DNA-RNA polymerase complexes, apparently bound to a fraction of the cell membrane of bacteriophage T2- or T4-infected Escherichia coli, are described. Evidence is presented to show that the complexes initiate the asymmetric synthesis of RNA, and release the finished product. The transcription capacity per unit of beta' + beta was 10 times higher at 6 min than at 30 min after infection.

Cell Membrane↗
PubMed1975

Phospholipase activity in bacteriophage-infected Escherichia coli. III. Phopholipase A involvement in lysis of T4-infected cells.

Bacteriophage studies with Escherichia coli K-12 (gamma)DR-DS-, a mutant lacking the major known fatty acyl hydrolases (phospholipases), and its wild-type parent showed equivalent phage infection with regard to phage production and time of phage release. Further examination of the DR-DS- mutant, however, revealed that the progeny bacteriophage were released without complete dissolution of the host cell. Prolonged cell integrity of the infected mutant was noted by spectrophotometry and supported by direct microscope examination. The phage release occurred at normal "lysis" time with phage yields comparable to that of the wild-type bacteria. Inner membrane degradation was indicated by the release of beta-galactosidase, a cytoplasmic enzyme, and of trichloracetic acid-precipitable RNA. Thus, outer membrane degradation is required for dissolution of phage-infected cells, and this degradation is at least partly dependent on activation of host phospholipases.

Bacterial Proteins↗
PubMed1968

Antiviral agent from lambda-infected Escherichia coli K-12. I. Isolation.

Phagicin, which is an antiviral agent active against deoxyribonucleic acid (DNA) viruses such as vaccinia and herpes simplex, has been identified as a phage internal protein. It was found in infected Escherichia coli lysates, but could also be obtained by disruption of the purified infective particles after incubation with LiCl at 46 C for 15 min or by sonic treatment. After centrifugation at high speed, the antiviral activity was found in the DNA phase and could be separated by chromatography on Sephadex gels with 0.2 M phosphate buffer (pH 7.5) as the eluent. Phagicin present in lysates after removal of infective particles was nondialyzable and was bound to nucleic acids. It could be released during precipitation of nucleic acids by streptomycin sulfate, and in this form it could be easily dialyzed. The antiviral activity of phagicin was specific for herpes simplex and vaccinia viruses.

Animals↗