scholarly journals RESTORATION INDUCED BY CATALASE IN IRRADIATED MICROORGANISMS

1952 ◽  
Vol 35 (3) ◽  
pp. 455-470 ◽  
Author(s):  
Raymond Latarjet ◽  
Luis Renato Caldas ◽  
Keyword(s):  
Uv Irradiation ◽  
General Problem ◽  
None None ◽  
Chemical Nature ◽  
Coli Strain ◽  
E Coli ◽  
Physiological Conditions ◽  
X Irradiation ◽  
Phage Production ◽  
K 12

1. E. coli, strain K-12, and B. megatherium 899, irradiated in strict but still undefined physiological conditions with certain heavy doses of ultraviolet light, are efficiently restored by catalase, which acts on or fixes itself upon the bacteria in a few minutes. This restoration (C. R.), different from photorestoration, is aided by a little visible light. 2. At 37° the restorability lasts for about 2 hours after UV irradiation; the restored cells begin to divide at the same time as the normal survivors. 3. C. R. is not produced after x-irradiation. 4. B. megatherium Mox and E. coli, strain B/r show little C. R.; E. coli strain B shows none. None of these three strains is lysogenic, whereas the two preceding catalase-restorable strains are. 5. Phage production in the system "K-12 infected with T2 phage" is restored by catalase after UV irradiation, whereas phage production in the system "infected B" is not. 6. With K-12, catalase does not prevent the growth of phage and the lysis induced by UV irradiation (Lwoff's phenomenon). 7. Hypotheses are discussed concerning: (a) the chemical nature of this action of catalase; (b) a possible relation between C. R. and lysogenicity of the sensitive bacteria; (c) the consequences of such chemical restorations on the general problem of cell radiosensitivity.

scholarly journals H-NS Regulates DNA Repair inShigella

1998 ◽  
Vol 180 (19) ◽  
pp. 5260-5262 ◽  
Author(s):  
Sunil Palchaudhuri ◽  
Brandon Tominna ◽  
Myron A. Leon
Keyword(s):  
Dna Repair ◽  
Uv Irradiation ◽  
Shigella Flexneri ◽  
Virulence Gene ◽  
High Rate ◽  
High Survival ◽  
Virulence Gene Expression ◽  
E Coli ◽  
X Irradiation ◽  
K 12

ABSTRACT We report a new role for H-NS in Shigella spp.: suppression of repair of DNA damage after UV irradiation. H-NS-mediated suppression of virulence gene expression is thermoregulated inShigella, being functional at 30°C and nonfunctional at 37 to 40°C. We find that H-NS-mediated suppression of DNA repair after UV irradiation is also thermoregulated. Thus, Shigella flexneri M90T, incubated at 37 or 40°C postirradiation, shows up to 30-fold higher survival than when incubated at 30°C postirradiation. The hns mutants BS189 and BS208, both of which lack functional H-NS, show a high rate of survival (no repression) whether incubated at 30 or 40°C postirradiation. Suppression of DNA repair by H-NS is not mediated through genes on the invasion plasmid of S. flexneri M90T, since BS176, cured of plasmid, behaves identically to the parental M90T. Thus, inShigella the nonfunctionality of H-NS permits enhanced DNA repair at temperatures encountered in the human host. However, pathogenic Escherichia coli strains (enteroinvasive and enterohemorrhagic E. coli) show low survival whether incubated at 30 or 40°C postirradiation. E. coli K-12 shows markedly different behavior; high survival postirradiation at both 30 and 40°C. These K-12 strains were originally selected fromE. coli organisms subjected to both UV and X irradiation. Therefore, our data suggest that repair processes, extensively described for laboratory strains of E. coli, require experimental verification in pathogenic strains which were not adapted to irradiation.

scholarly journals Cation Transport in Escherichia coli

1961 ◽  
Vol 45 (2) ◽  
pp. 355-369 ◽  
Author(s):  
Stanley G. Schultz ◽  
A. K. Solomon
Keyword(s):  
Growth Medium ◽  
Bacterial Culture ◽  
Coli Strain ◽  
Metabolic Energy ◽  
Logarithmic Phase ◽  
Concentration Gradients ◽  
E Coli ◽  
Ion Movements ◽  
K Concentration ◽  
K 12

Methods have been developed to study the intracellular Na and K concentrations in E. coli, strain K-12. These intracellular cation concentrations have been shown to be functions of the extracellular cation concentrations and the age of the bacterial culture. During the early logarithmic phase of growth, the intracellular K concentration greatly exceeds that of the external medium, whereas the intracellular Na concentration is lower than that of the growth medium. As the age of the culture increases, the intracellular K concentration falls and the intracellular Na concentration rises, changes which are related to the fall in the pH of the medium and to the accumulation of the products of bacterial metabolism. When stationary phase cells, which are rich in Na and poor in K, are resuspended in fresh growth medium, there is a rapid reaccumulation of K and extrusion of Na. These processes represent oppositely directed net ion movements against concentration gradients, and have been shown to be dependent upon the presence of an intact metabolic energy supply.

scholarly journals The lipopolysaccharide of the mastitis isolate Escherichia coli strain 1303 comprises a novel O-antigen and the rare K-12 core type

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1750-1760 ◽  
Author(s):  
Katarzyna A. Duda ◽  
Buko Lindner ◽  
Helmut Brade ◽  
Andreas Leimbach ◽  
Elżbieta Brzuszkiewicz ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Inner Core ◽  
Bovine Mastitis ◽  
Outer Core ◽  
Coli Strain ◽  
Core Oligosaccharide ◽  
2D Nmr Spectroscopy ◽  
E Coli ◽  
O Antigen ◽  
K 12

Mastitis represents one of the most significant health problems of dairy herds. The two major causative agents of this disease are Escherichia coli and Staphylococcus aureus. Of the first, its lipopolysaccharide (LPS) is thought to play a prominent role during infection. Here, we report the O-antigen (OPS, O-specific polysaccharide) structure of the LPS from bovine mastitis isolate E. coli 1303. The structure was determined utilizing chemical analyses, mass spectrometry, and 1D and 2D NMR spectroscopy methods. The O-repeating unit was characterized as -[→4)-β-d-Quip3NAc-(1→3)-α-l-Fucp2OAc-(1→4)-β-d-Galp-(1→3)-α-d-GalpNAc-(1→]- in which the O-acetyl substitution was non-stoichiometric. The nucleotide sequence of the O-antigen gene cluster of E. coli 1303 was also determined. This cluster, located between the gnd and galF genes, contains 13 putative open reading frames, most of which represent unknown nucleotide sequences that have not been described before. The O-antigen of E. coli 1303 was shown to substitute O-7 of the terminal ld-heptose of the K-12 core oligosaccharide. Interestingly, the non-OPS-substituted core oligosaccharide represented a truncated version of the K-12 outer core – namely terminal ld-heptose and glucose were missing; however, it possessed a third Kdo residue in the inner core. On the basis of structural and genetic data we show that the mastitis isolate E. coli 1303 represents a new serotype and possesses the K-12 core type, which is rather uncommon among human and bovine isolates.

Characterization of the flexible genome complement of the commensal Escherichia coli strain A0 34/86 (O83 : K24 : H31)

Microbiology ◽  
2005 ◽  
Vol 151 (2) ◽  
pp. 385-398 ◽  
Author(s):  
Jana Hejnova ◽  
Ulrich Dobrindt ◽  
Radka Nemcova ◽  
Christophe Rusniok ◽  
Alojz Bomba ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Multiplex Pcr ◽  
Gene Clusters ◽  
Coli Strain ◽  
Bac Clone ◽  
Sequence Comparisons ◽  
Multiple Sequence ◽  
E Coli ◽  
Gut Colonization ◽  
K 12

Colonization by the commensal Escherichia coli strain A0 34/86 (O83 : K24 : H31) has proved to be safe and efficient in the prophylaxis and treatment of nosocomial infections and diarrhoea of preterm and newborn infants in Czech paediatric clinics over the past three decades. In searching for traits contributing to this beneficial effect related to the gut colonization capacity of the strain, the authors have analysed its genome by DNA–DNA hybridization to E. coli K-12 (MG1655) genomic DNA arrays and to ‘Pathoarrays’, as well as by multiplex PCR, bacterial artificial chromosome (BAC) library cloning and shotgun sequencing. Four hundred and ten E. coli K-12 ORFs were absent from A0 34/86, while 72 out of 456 genes associated with pathogenicity islands of E. coli and Shigella were also detected in E. coli A0 34/86. Furthermore, extraintestinal pathogenic E. coli-related genes involved in iron uptake and adhesion were detected by multiplex PCR, and genes encoding the HlyA and cytotoxic necrotizing factor toxins, together with 21 genes of the uropathogenic E. coli 536 pathogenicity island II, were identified by analysis of 2304 shotgun and 1344 BAC clone sequences of A0 34/86 DNA. Multiple sequence comparisons identified 31 kb of DNA specific for E. coli A0 34/86; some of the genes carried by this DNA may prove to be implicated in the colonization capacity of the strain, enabling it to outcompete pathogens. Among 100 examined BAC clones roughly covering the A0 34/86 genome, one reproducibly conferred on the laboratory strain DH10B an enhanced capacity to persist in the intestine of newborn piglets. Sequencing revealed that this BAC clone carried gene clusters encoding gluconate and mannonate metabolism, adhesion (fim), invasion (ibe) and restriction/modification functions. Hence, the genome of this clinically safe and highly efficient colonizer strain appears to harbour many ‘virulence-associated’ genes. These results highlight the thin line between bacterial ‘virulence’ and ‘fitness' or ‘colonization’ factors, and question the definition of enterobacterial virulence factors.

A SitABCD homologue from an avian pathogenic Escherichia coli strain mediates transport of iron and manganese and resistance to hydrogen peroxide

Microbiology ◽  
2006 ◽  
Vol 152 (3) ◽  
pp. 745-758 ◽  
Author(s):  
Mourad Sabri ◽  
Simon Léveillé ◽  
Charles M. Dozois
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Growth Promotion ◽  
Coli Strain ◽  
Transport Systems ◽  
Virulence Plasmid ◽  
E Coli ◽  
K 12 ◽  
Iron And Manganese

An operon encoding a member of the family of ATP-binding cassette (ABC) divalent metal ion transporters, homologous to Salmonella enterica SitABCD, has been identified in the avian pathogenic Escherichia coli (APEC) strain χ7122. The sitABCD genes were located on the virulence plasmid pAPEC-1, and were highly similar at the nucleotide level to the chromosomally encoded sitABCD genes present in Shigella spp. A cloned copy of sitABCD conferred increased growth upon a siderophore-deficient E. coli strain grown in nutrient broth supplemented with the chelator 2,2′-dipyridyl. Ion rescue demonstrated that Sit-mediated growth promotion of this strain was due to the transport of iron. SitABCD mediated increased transport of both iron and manganese as demonstrated by uptake of 55Fe, 59Fe or 54Mn in E. coli K-12 strains deficient for the transport of iron (aroB feoB) and manganese (mntH) respectively. Isotope uptake and transport inhibition studies showed that in the iron transport deficient strain, SitABCD demonstrated a greater affinity for iron than for manganese, and SitABCD-mediated transport was higher for ferrous iron, whereas in the manganese transport deficient strain, SitABCD demonstrated greater affinity for manganese than for iron. Introduction of the APEC sitABCD genes into an E. coli K-12 mntH mutant also conferred increased resistance to the bactericidal effects of hydrogen peroxide. APEC strain χ7122 derivatives lacking either a functional SitABCD or a functional MntH transport system were as resistant to hydrogen peroxide as the wild-type strain, whereas a Δsit ΔmntH double mutant was more sensitive to hydrogen peroxide. Overall, the results demonstrate that in E. coli SitABCD represents a manganese and iron transporter that, in combination with other ion transport systems, may contribute to acquisition of iron and manganese, and resistance to oxidative stress.

Cloning and expression of the beta-D-phosphogalactoside galactohydrolase gene of Lactobacillus casei in Escherichia coli K-12

1982 ◽  
Vol 152 (3) ◽  
pp. 1138-1146
Author(s):  
L J Lee ◽  
J B Hansen ◽  
E K Jagusztyn-Krynicka ◽  
B M Chassy
Keyword(s):  
Escherichia Coli ◽  
Lactobacillus Casei ◽  
Specific Activity ◽  
Protein Product ◽  
Coli Strain ◽  
Cloning And Expression ◽  
E Coli ◽  
Lactose Metabolism ◽  
Gene Coding ◽  
K 12

Lactose metabolism in Lactobacillus casei 64H is associated with the presence of plasmid pLZ64. This plasmid determines both phosphoenolpyruvate-dependent phosphotransferase uptake of lactose and beta-D-phosphogalactoside galactohydrolase. A shotgun clone bank of chimeric plasmids containing restriction enzyme digest fragments of pLZ64 DNA was constructed in Escherichia coli K-12. One clone contained the gene coding for beta-D-phosphogalactoside galactohydrolase on a 7.9-kilobase PstI fragment cloned into the vector pBR322 in E. coli strain chi 1849. The beta-D-phosphogalactoside galactohydrolase enzyme isolated from E. coli showed no difference from that isolated from L. casei, and specific activity of beta-D-phosphogalactoside galactohydrolase was stimulated 1.8-fold in E. coli by growth in media containing beta-galactosides. A restriction map of the recombinant plasmid was compiled, and with that information, a series of subclones was constructed. From an analysis of the proteins produced by minicells prepared from transformant E. coli cells containing each of the recombinant subclone plasmids, it was found that the gene for the 56-kilodalton beta-D-phosphogalactoside galactohydrolase was transcribed from an L. casei-derived promoter. The gene for a second protein product (43 kilodaltons) was transcribed in the opposite direction, presumably under the control of a promoter in pBR322. The relationship of this second product to the lactose metabolism genes of L. casei is at present unknown.

STUDIES ON MECHANISM OF REPAIR OF ULTRAVIOLET-IRRADIATED VIRAL AND BACTERIAL DNA IN VIVO AND IN VITRO

1965 ◽  
Vol 43 (7) ◽  
pp. 1207-1219 ◽  
Author(s):  
Emanuel Riklis
Keyword(s):  
Uv Irradiation ◽  
Soluble Fraction ◽  
Cell Extract ◽  
Host Cells ◽  
Bacterial Dna ◽  
E Coli ◽  
Thymine Dimers ◽  
K 12

The formation of thymine dimers [Formula: see text] from adjacent intrastrand thymines by ultraviolet (UV) irradiation in DNA was studied under different conditions. When thymine-2-C14 DNA was exposed in quartz tubes to 0.5 × 106 ergs/mm2 ultraviolet irradiation, two photoproducts were formed: "a" + [Formula: see text]. The concentration formed in dry DNA was only about [Formula: see text] of that formed in wet DNA.The survival of T1 phage in the dark in the resistant (uvr+) and the sensitive (uvr−) mutants of E. coli K-12 after UV irradiation of the phage in the wet and dry state is markedly dependent on the state of the phage during irradiation. Survival of T1 phage, when UV irradiated dry, was the same in the sensitive as in the resistant host cells, over a wide range of UV doses, while a marked difference in sensitivity existed when it was UV irradiated wet. Similar survival was obtained also by photoreactivation. These results correspond with the notion that thymine dimers are involved both in photoreactivation and in dark (host cell) reactivation.Thymine-requiring E. coli K-12 cells were mutated to a radioresistant strain uvr+ (AB 2416) and a radiosensitive strain uvr− (AB 2419).Irradiation of cells with a dose of 1000 ergs/mm2, followed by incubation of the cells in the dark in enriched M9 media, stopped by addition of 5% trichloroacetic acid, hydrolysis of the acid-insoluble fraction and the acid-soluble fraction in trifluoroacetic acid at 175 °C, and separation of the products by paper chromatography, showed that the two irradiation products "a" + [Formula: see text], which were formed in the bacterial DNA, are excised from the DNA in the uvr+ strain and appear in the acid-soluble fraction. No such excision occurred upon incubation of the radiosensitive strain uvr−.Incubation of the cells under light showed that photoreactivation prevails in the radiosensitive strain, i.e. disappearance of "a" + [Formula: see text] from the DNA, without their appearance in the acid-soluble fraction, while dark reactivation prevailed in the uvr+ strain, a result that indicates a stronger affinity of the dark reactivating system to UV-irradiated DNA. Cell extracts prepared by breaking the cells in a French press in Tris buffer, pH 7.5, plus 10−3 M Mg++ plus 10−3 M mercapto-ethanol showed a similar mechanism; the two irradiation products were excised from DNA by a uvr+ cell extract and not by a uvr− cell extract. Extract of uvr+ cells brought about excision of photoproducts from DNA of the uvr− cell extract.The results suggest that an enzyme, capable of excising thymine dimers, is present in the radioresistant cell as part of the system of repair of DNA from UV irradiation, and its mechanism is demonstrated, both in vivo and in vitro.

scholarly journals A Commensal Gone Bad: Complete Genome Sequence of the Prototypical Enterotoxigenic Escherichia coli Strain H10407

2010 ◽  
Vol 192 (21) ◽  
pp. 5822-5831 ◽  
Author(s):  
Lisa C. Crossman ◽  
Roy R. Chaudhuri ◽  
Scott A. Beatson ◽  
Timothy J. Wells ◽  
Mickael Desvaux ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Genomic Sequence ◽  
Epidemiological Data ◽  
Coli Strain ◽  
Enterotoxigenic Escherichia Coli ◽  
E Coli ◽  
Extraintestinal Disease ◽  
K 12 ◽  
Genetic Context ◽  
Complete Genomic

ABSTRACT In most cases, Escherichia coli exists as a harmless commensal organism, but it may on occasion cause intestinal and/or extraintestinal disease. Enterotoxigenic E. coli (ETEC) is the predominant cause of E. coli-mediated diarrhea in the developing world and is responsible for a significant portion of pediatric deaths. In this study, we determined the complete genomic sequence of E. coli H10407, a prototypical strain of enterotoxigenic E. coli, which reproducibly elicits diarrhea in human volunteer studies. We performed genomic and phylogenetic comparisons with other E. coli strains, revealing that the chromosome is closely related to that of the nonpathogenic commensal strain E. coli HS and to those of the laboratory strains E. coli K-12 and C. Furthermore, these analyses demonstrated that there were no chromosomally encoded factors unique to any sequenced ETEC strains. Comparison of the E. coli H10407 plasmids with those from several ETEC strains revealed that the plasmids had a mosaic structure but that several loci were conserved among ETEC strains. This study provides a genetic context for the vast amount of experimental and epidemiological data that have been published.

scholarly journals S-Fimbria-Encoding Determinant sfaI Is Located on Pathogenicity Island III536 of UropathogenicEscherichia coli Strain 536

2001 ◽  
Vol 69 (7) ◽  
pp. 4248-4256 ◽  
Author(s):  
Ulrich Dobrindt ◽  
Gabriele Blum-Oehler ◽  
Thomas Hartsch ◽  
Gerhard Gottschalk ◽  
Eliora Z. Ron ◽  
...  
Keyword(s):  
Insertion Sequence ◽  
Pathogenicity Island ◽  
Coli Strain ◽  
E Coli ◽  
Sequence Elements ◽  
Fimbrial Adhesins ◽  
Colicin V ◽  
K 12 ◽  
Insertion Sequence Elements ◽  
Fimbrial Adhesin

ABSTRACT The sfa I determinant encoding the S-fimbrial adhesin of uropathogenic Escherichia colistrains was found to be located on a pathogenicity island of uropathogenic E. coli strain 536. This pathogenicity island, designated PAI III536, is located at 5.6 min of theE. coli chromosome and covers a region of at least 37 kb between the tRNA locus thrW and yagU. As far as it has been determined, PAI III536 also contains genes which code for components of a putative enterochelin siderophore system of E. coli and Salmonella spp. as well as for colicin V immunity. Several intact or nonfunctional mobility genes of bacteriophages and insertion sequence elements such as transposases and integrases are present on PAI III536. The presence of known PAI III536 sequences has been investigated in several wild-type E. coli isolates. The results demonstrate that the determinants of the members of the S-family of fimbrial adhesins may be located on a common pathogenicity island which, in E. coli strain 536, replaces a 40-kb DNA region which represents anE. coli K-12-specific genomic island.

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