scholarly journals Characterization of a Shiga Toxin-Encoding Temperate Bacteriophage of Shigella sonnei

2001 ◽  
Vol 69 (12) ◽  
pp. 7588-7595 ◽  
Author(s):  
Eckhard Strauch ◽  
Rudi Lurz ◽  
Lothar Beutin
Keyword(s):  
Shiga Toxin ◽  
Regulatory Region ◽  
Shigella Sonnei ◽  
Shigella Dysenteriae ◽  
Nucleotide Sequencing ◽  
Temperate Bacteriophage ◽  
Cross Hybridization ◽  
E Coli ◽  
K 12

ABSTRACT A Shiga toxin (Stx)-encoding temperate bacteriophage ofShigella sonnei strain CB7888 was investigated for its morphology, DNA similarity, host range, and lysogenization inShigella and Escherichia coli strains. Phage 7888 formed plaques on a broad spectrum of Shigella strains belonging to different species and serotypes, including Stx-producingShigella dysenteriae type 1. With E. coli, only strains with rough lipopolysaccharide were sensitive to this phage. The phage integrated into the genome of nontoxigenic S. sonneiand laboratory E. coli K-12 strains, which became Stx positive upon lysogenization. Moreover, phage 7888 is capable of transducing chromosomal genes in E. coli K-12. The relationships of phage 7888 with the E. coli Stx1-producing phage H-19B and the E. coli Stx2-producing phage 933W were investigated by DNA cross-hybridization of phage genomes and by nucleotide sequencing of an 8,053-bp DNA region of the phage 7888 genome flanking the stx genes. By these methods, a high similarity was found between phages 7888 and 933W. Much less similarity was found between phages H-19B and 7888. As in the other Stx phages, a regulatory region involved in Q-dependent expression is found upstream of stxA and stxB (stx gene) in phage 7888. The morphology of phage 7888 was similar to that of phage 933W, which shows a hexagonal head and a short tail. Our findings demonstrate that stx genes are naturally transferable and are expressed in strains of S. sonnei, which points to the continuous evolution of human-pathogenic Shigella by horizontal gene transfer.

scholarly journals Structural Analysis of Phage-Borne stx Genes and Their Flanking Sequences in Shiga Toxin-Producing Escherichia coli and Shigella dysenteriae Type 1 Strains

2000 ◽  
Vol 68 (9) ◽  
pp. 4856-4864 ◽  
Author(s):  
Alexandra Unkmeir ◽  
Herbert Schmidt
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Shigella Dysenteriae ◽  
Nucleotide Sequencing ◽  
Restriction Patterns ◽  
E Coli ◽  
Pcr Products ◽  
Flanking Region ◽  
Flanking Regions

ABSTRACT The stx-flanking regions of 49 Shiga toxin-producingEscherichia coli strains and nine Shigella dysenteriae serotype 1 strains containing either stx,stx 1, stx 2, orstx 2 variant genes, were examined. We analyzed these regions by PCR using a set of primers with one primer specific for the respective stx gene and a second primer complementary to sequences of Stx phages H-19B and 933W. We further characterized the amplification products by restriction endonuclease digestion and nucleotide sequencing. PCR products ofstx 1-containing E. coli strains of serogroups O157, O26, and 0103 showed the same lengths and similar restriction patterns. However, we failed to amplify the 3′stx-flanking region instx 1-harboring E. coliO111:H− strains. Stx2-producing E. colistrains revealed amplification products of different lengths and restriction patterns, suggesting greater heterogeneity than instx 1-positive strains. We also obtained specific PCR products for two Stx2c-producing and seven Stx2f-producingE. coli strains when they were subjected to PCR analysis. In nine S. dysenteriae type 1 strains, H-19B- and 933W-specific primers amplified only the 3′ stx-flanking region. The results of our study demonstrate that the stxgenes of all strains investigated are continuous with phage sequences. Whereas almost all strains except E. coliO111:H− strains were associated with a S-like gene, association with Q could not be demonstrated in nine S. dysenteriae type 1 strains and three E. coli strains. Furthermore, we showed that the organization of thestx-flanking regions is similar in all strains investigated, whereas fine-structure analysis showed subtle differences among the sequences examined. Our results support the hypothesis thatstx genes in E. coli and S. dysenteriae are generally phage-borne.

scholarly journals Identification and Characterization of a Newly Isolated Shiga Toxin 2-Converting Phage from Shiga Toxin-ProducingEscherichia coli

1998 ◽  
Vol 66 (9) ◽  
pp. 4100-4107 ◽  
Author(s):  
Masahisa Watarai ◽  
Toshio Sato ◽  
Midori Kobayashi ◽  
Takeshi Shimizu ◽  
Shinji Yamasaki ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Plating Efficiency ◽  
Restriction Maps ◽  
Shiga Toxins ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Formal Science ◽  
K 12 ◽  
Identification And Characterization

ABSTRACT Shiga toxins 1 (Stx1) and 2 (Stx2) are encoded by toxin-converting bacteriophages of Stx-producing Escherichia coli (STEC), and so far two Stx1- and one Stx2-converting phages have been isolated from two STEC strains (A. D. O’Brien, J. W. Newlands, S. F. Miller, R. K. Holmes, H. W. Smith, and S. B. Formal, Science 226:694–696, 1984). In this study, we isolated two Stx2-converting phages, designated Stx2Φ-I and Stx2Φ-II, from two clinical strains of STEC associated with the outbreaks in Japan in 1996 and found that Stx2Φ-I resembled 933W, the previously reported Stx2-converting phage, in its infective properties for E. coli K-12 strain C600 while Stx2Φ-II was distinct from them. The sizes of the plaques of Stx2Φ-I and Stx2Φ-II in C600 were different; the former was larger than the latter. The restriction maps of Stx2Φ-I and Stx2Φ-II were not identical; rather, Stx2Φ-II DNA was approximately 3 kb larger than Stx2Φ-I DNA. Furthermore, Stx2Φ-I and Stx2Φ-II showed different phage immunity, with Stx2Φ-I and 933W belonging to the same group. Infection of C600 by Stx2Φ-I or 933W was affected by environmental osmolarity differently from that by Stx2Φ-II. When C600 was grown under conditions of high osmolarity, the infectivity of Stx2Φ-I and 933W was greatly decreased compared with that of Stx2Φ-II. Examination of the plating efficiency of the three phages for the defined mutations in C600 revealed that the efficiency of Stx2Φ-I and 933W for the fadL mutant decreased to less than 10−7 compared with that for C600 whereas the efficiency of Stx2Φ-II decreased to 0.1% of that for C600. In contrast, while the plating efficiency of Stx2Φ-II for thelamB mutant decreased to a low level (0.05% of that for C600), the efficiencies of Stx2Φ-I and 933W were not changed. This was confirmed by the phage neutralization experiments with isolated outer membrane fractions from C600, fadL mutant, or lamB mutant or the purified His6-tagged FadL and LamB proteins. Based on the data, we concluded that FadL acts as the receptor for Stx2Φ-I and Stx2Φ-II whereas LamB acts as the receptor only for Stx2Φ-II.

scholarly journals The Escherichia coli K-12 NarL and NarP Proteins Insulate the nrf Promoter from the Effects of Integration Host Factor

2006 ◽  
Vol 188 (21) ◽  
pp. 7449-7456 ◽  
Author(s):  
Douglas F. Browning ◽  
David J. Lee ◽  
Alan J. Wolfe ◽  
Jeffrey A. Cole ◽  
Stephen J. W. Busby
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
Regulatory Region ◽  
Enteric Bacteria ◽  
Integration Host Factor ◽  
Host Factor ◽  
Receptor Protein ◽  
E Coli ◽  
Serovar Typhimurium ◽  
K 12

ABSTRACT The Escherichia coli K-12 nrf operon promoter can be activated fully by the FNR protein (regulator of fumarate and nitrate reduction) binding to a site centered at position −41.5. FNR-dependent transcription is suppressed by integration host factor (IHF) binding at position −54, and this suppression is counteracted by binding of the NarL or NarP response regulator at position −74.5. The E. coli acs gene is transcribed from a divergent promoter upstream from the nrf operon promoter. Transcription from the major acsP2 promoter is dependent on the cyclic AMP receptor protein and is modulated by IHF and Fis binding at multiple sites. We show that IHF binding to one of these sites, located at position −127 with respect to the nrf promoter, has a positive effect on nrf promoter activity. This activation is dependent on the face of the DNA helix, independent of IHF binding at other locations, and found only when NarL/NarP are not bound at position −74.5. Binding of NarL/NarP appears to insulate the nrf promoter from the effects of IHF. The acs-nrf regulatory region is conserved in other pathogenic E. coli strains and related enteric bacteria but differs in Salmonella enterica serovar Typhimurium.

scholarly journals First-Time Isolation and Characterization of a Bacteriophage Encoding the Shiga Toxin 2c Variant, Which Is Globally Spread in Strains of Escherichia coli O157

2004 ◽  
Vol 72 (12) ◽  
pp. 7030-7039 ◽  
Author(s):  
Eckhard Strauch ◽  
Christoph Schaudinn ◽  
Lothar Beutin
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Phage Lambda ◽  
Wild Type ◽  
Chromosomal Locus ◽  
O157 Strain ◽  
Diagnostic Pcr ◽  
E Coli ◽  
Isolation And Characterization ◽  
K 12

ABSTRACT A bacteriophage encoding the Shiga toxin 2c variant (Stx2c) was isolated from the human Escherichia coli O157 strain CB2851 and shown to form lysogens on the E. coli K-12 laboratory strains C600 and MG1655. Production of Stx2c was found in the wild-type E. coli O157 strain and the K-12 lysogens and was inducible by growing bacteria in the presence of ciprofloxacin. Phage 2851 is the first reported viable bacteriophage which carries an stx 2c gene. Electron micrographs of phage 2851 showed particles with elongated hexagonal heads and long flexible tails resembling phage lambda. Sequence analysis of an 8.4-kb region flanking the stx 2c gene and other genetic elements revealed a mosaic gene structure, as found in other Stx phages. Phage 2851 showed lysis of E. coli K-12 strains lysogenic for Stx phages encoding Stx1 (H19), Stx2 (933W), Stx (7888), and Stx1c (6220) but showed superinfection immunity with phage lambda, presumably originating from the similarity of the cI repressor proteins of both phages. Apparently, phage 2851 integrates at a different chromosomal locus than Stx2 phage 933W and Stx1 phage H19 in E. coli, explaining why Stx2c is often found in combination with Stx1 or Stx2 in E. coli O157 strains. Diagnostic PCR was performed to determine gene sequences specific for phage 2851 in wild-type E. coli O157 strains producing Stx2c. The phage 2851 q and o genes were frequently detected in Stx2c-producing E. coli O157 strains, indicating that phages related to 2851 are associated with Stx2c production in strains of E. coli O157 that were isolated in different locations and time periods.

Characterization of Shiga toxin producing E. coli and O157 serotype E. coli isolated in France from healthy domestic cattle

2001 ◽  
Vol 63 (3) ◽  
pp. 217-223 ◽  
Author(s):  
François Rogerie ◽  
Armelle Marecat ◽  
Stéphanie Gambade ◽  
Francis Dupond ◽  
Pierre Beaubois ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
E Coli

scholarly journals Fully Automated Microsystem for Unmediated Electrochemical Characterization, Visualization and Monitoring of Bacteria on Solid Media; E. coli K-12: A Case Study

Biosensors ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 131 ◽  
Author(s):  
Cesar A. Hernandez ◽  
Valerio Beni ◽  
Johann F. Osma
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Tests ◽  
E Coli ◽  
Solid Media ◽  
Automated Platform ◽  
The Moment ◽  
K 12 ◽  
Electrochemical Monitoring

In this paper, we present a non-fluidic microsystem for the simultaneous visualization and electrochemical evaluation of confined, growing bacteria on solid media. Using a completely automated platform, real-time monitoring of bacterial and image-based computer characterization of growth were performed. Electrochemical tests, using Escherichia coli K-12 as the model microorganism, revealed the development of a faradaic process at the bacteria–microelectrode interface inside the microsystem, as implied by cyclic voltammetry and electrochemical impedance spectrometry measurements. The electrochemical information was used to determine the moment in which bacteria colonized the electrode-enabled area of the microsystem. This microsystem shows potential advantages for long-term electrochemical monitoring of the extracellular environment of cell culture and has been designed using readily available technologies that can be easily integrated in routine protocols. Complementarily, these methods can help elucidate fundamental questions of the electron transfer of bacterial cultures and are potentially feasible to be integrated into current characterization techniques.

scholarly journals Characterization of Shiga Toxin-ProducingEscherichia coliIsolated from Ground Beef Collected in Different Socioeconomic Strata Markets in Buenos Aires, Argentina

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Patricia Llorente ◽  
Laura Barnech ◽  
Kinue Irino ◽  
María Valeria Rumi ◽  
Adriana Bentancor
Keyword(s):  
Shiga Toxin ◽  
Buenos Aires ◽  
Ground Beef ◽  
Contamination Level ◽  
Contamination Rate ◽  
E Coli ◽  
Virulence Markers ◽  
Route Of Transmission ◽  
Socioeconomic Strata

Consumption of raw/undercooked ground beef is the most common route of transmission of Shiga toxin-producingE. coli(STEC). The aim of the study was to determine the STEC contamination level of the ground beef samples collected in 36 markets of different socioeconomic strata in Buenos Aires, Argentina, and the characterization of the isolated strains. Ninety-one out of 252 (36.1%) samples werestx+. Fifty-seven STEC strains were recovered. Eleven STEC strains belonged to O157 serogroup, and 46 to non-O157 serogroups. Virulence markers of the 57 STEC werestx1, 5.3% (3/57);stx2, 86.0% (49/57);stx1/stx2, 8.8% (5/57);ehxA, 61.4% (35/57);eae, 26.3% (15/57);saa, 24.6% (14/57). Shiga toxin subtypes werestx2, 31.5% (17/54);stx2c-vhb, 24.1% (13/54);stx2c-vha, 20.4% (11/54);stx2/stx2c-vha, 14.8% (8/54);stx2/stx2c-vhb, 5.6% (3/54);stx2c-vha/vhb, 3.7% (2/54). Serotypes O178:H19 and O157:H7 were prevalent. Contamination rate of STEC in all strata was high, and the highest O157 contamination was observed at low strata at several sampling rounds. Persistence of STEC was not detected. Sixteen strains (28.1%) were resistant to ampicillin, streptomycin, amikacin, or tetracycline. The STEC contamination level of ground beef could vary according to the sociocultural characteristics of the population.

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