scholarly journals Short-Tailed Stx Phages Exploit the Conserved YaeT Protein To Disseminate Shiga Toxin Genes among Enterobacteria

2007 ◽  
Vol 189 (20) ◽  
pp. 7223-7233 ◽  
Author(s):  
Darren L. Smith ◽  
Chloë E. James ◽  
Martin J. Sergeant ◽  
Yan Yaxian ◽  
Jon R. Saunders ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Bacterial Species ◽  
Erwinia Carotovora ◽  
Underlying Mechanism ◽  
Toxin Production ◽  
E Coli ◽  
Phage Adsorption ◽  
Commensal Flora ◽  
Conserved Gene

ABSTRACT Infection of Escherichia coli by Shiga toxin-encoding bacteriophages (Stx phages) was the pivotal event in the evolution of the deadly Shiga toxin-encoding E. coli (STEC), of which serotype O157:H7 is the most notorious. The number of different bacterial species and strains reported to produce Shiga toxin is now more than 500, since the first reported STEC infection outbreak in 1982. Clearly, Stx phages are spreading rapidly, but the underlying mechanism for this dissemination has not been explained. Here we show that an essential and highly conserved gene product, YaeT, which has an essential role in the insertion of proteins in the gram-negative bacterial outer membrane, is the surface molecule recognized by the majority (ca. 70%) of Stx phages via conserved tail spike proteins associated with a short-tailed morphology. The yaeT gene was initially identified through complementation, and its role was confirmed in phage binding assays with and without anti-YaeT antiserum. Heterologous cloning of E. coli yaeT to enable Stx phage adsorption to Erwinia carotovora and the phage adsorption patterns of bacterial species possessing natural yaeT variants further supported this conclusion. The use of an essential and highly conserved protein by the majority of Stx phages is a strategy that has enabled and promoted the rapid spread of shigatoxigenic potential throughout multiple E. coli serogroups and related bacterial species. Infection of commensal bacteria in the mammalian gut has been shown to amplify Shiga toxin production in vivo, and the data from this study provide a platform for the development of a therapeutic strategy to limit this YaeT-mediated infection of the commensal flora.

scholarly journals A putative microcin amplifies Shiga toxin 2a production ofEscherichia coliO157:H7

2019 ◽  
Author(s):  
Hillary M. Figler ◽  
Lingzi Xiaoli ◽  
Kakolie Banerjee ◽  
Maria Hoffmann ◽  
Kuan Yao ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Bacterial Infections ◽  
Bacterial Species ◽  
Treatment Options ◽  
Gene Clusters ◽  
Toxin Production ◽  
Additional Treatment ◽  
Proteinase K ◽  
Gut Microflora ◽  
E Coli

AbstractEscherichia coliO157:H7 is a foodborne pathogen, implicated in various multi-state outbreaks. It encodes Shiga toxin on a prophage, and Shiga toxin production is linked to phage induction. AnE. colistrain, designated 0.1229, was identified that amplified Stx2a production when co-cultured withE. coliO157:H7 strain PA2. Growth of PA2 in 0.1229 cell-free supernatants had a similar effect, even when supernatants were heated to 100°C for 10 min, but not after treatment with Proteinase K. The secreted molecule was shown to use TolC for export and the TonB system for import. The genes sufficient for production of this molecule were localized to a 5.2 kb region of a 12.8 kb plasmid. This region was annotated, identifying hypothetical proteins, a predicted ABC transporter, and a cupin superfamily protein. These genes were identified and shown to be functional in two otherE. colistrains, and bioinformatic analyses identified related gene clusters in similar and distinct bacterial species. These data collectively suggestE. coli0.1229 and otherE. coliproduce a microcin that induces the SOS response in target bacteria. Besides adding to the limited number of microcins known to be produced byE. coli, this study provides an additional mechanism by whichstx2aexpression is increased in response to the gut microflora.ImportanceHow the gut microflora influences the progression of bacterial infections is only beginning to be understood. Antibiotics are counter-indicated forE. coliO157:H7 infections, and therefore treatment options are limited. An increased understanding of how the gut microflora directs O157:H7 virulence gene expression may lead to additional treatment options. This work identifiedE. colithat enhance the production of Shiga toxin by O157:H7, through the secretion of a proposed microcin. This work demonstrates another mechanism by which non-O157E. colistrains may increase Shiga toxin production, and adds to our understanding of microcins, a group of antimicrobials that are less well understood than colicins.

scholarly journals Commensal Bacteria Influence Escherichia coli O157:H7 Persistence and Shiga Toxin Production in the Mouse Intestine

2006 ◽  
Vol 74 (3) ◽  
pp. 1977-1983 ◽  
Author(s):  
Shantini D. Gamage ◽  
Angela K. Patton ◽  
Jane E. Strasser ◽  
Claudia L. Chalk ◽  
Alison A. Weiss
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Toxin Production ◽  
Commensal Bacteria ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Commensal Flora ◽  
Mouse Intestine

ABSTRACT The presence of commensal flora reduced colonization of Escherichia coli O157:H7 and production of Shiga toxin (Stx) in the murine intestine. Stx production was not detected in mice colonized with E. coli that were resistant to the Shiga toxin phage, but it was detected in mice colonized with phage-susceptible E. coli.

scholarly journals Human Neutrophils and Their Products Induce Shiga Toxin Production by Enterohemorrhagic Escherichia coli

2001 ◽  
Vol 69 (3) ◽  
pp. 1934-1937 ◽  
Author(s):  
Patrick L. Wagner ◽  
David W. K. Acheson ◽  
Matthew K. Waldor
Keyword(s):  
Escherichia Coli ◽  
Clinical Isolate ◽  
Shiga Toxin ◽  
Toxin Production ◽  
Enterohemorrhagic Escherichia Coli ◽  
Human Neutrophils ◽  
Prophage Induction ◽  
Shiga Toxins ◽  
E Coli

ABSTRACT The Shiga toxins (Stx) are critical virulence factors forEscherichia coli O157:H7 and other serotypes of enterohemorrhagic E. coli (EHEC). These potent toxins are encoded in the genomes of temperate lambdoid bacteriophages. We recently demonstrated that induction of the resident Stx2-encoding prophage in an O157:H7 clinical isolate is required for toxin production by this strain. Since several factors produced by human cells, including hydrogen peroxide (H2O2), are capable of inducing lambdoid prophages, we hypothesized that such molecules might also induce toxin production by EHEC. Here, we studied whether H2O2 and also human neutrophils, an important endogenous source of H2O2, induced Stx2 expression by an EHEC clinical isolate. Both H2O2 and neutrophils were found to augment Stx2 production, raising the possibility that these agents may lead to prophage induction in vivo and thereby contribute to EHEC pathogenesis.

scholarly journals A Toxic Environment: a Growing Understanding of How Microbial Communities Affect Escherichia coli O157:H7 Shiga Toxin Expression

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Erin M. Nawrocki ◽  
Hillary M. Mosso ◽  
Edward G. Dudley
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Microbial Interactions ◽  
Severe Illness ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Lambdoid Prophage

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of disease outcomes: some infections are relatively mild, while others have serious complications. Probiotic organisms, members of the gut microbiome, and organic acids can depress Stx production, in many cases by inhibiting the growth of EHEC strains. On the other hand, the factors currently known to amplify Stx act via their effect on the stx-converting phage. Here, we characterize two interactive mechanisms that increase Stx production by O157:H7 strains: first, direct interactions with phage-susceptible E. coli, and second, indirect amplification by secreted factors. Infection of susceptible strains by the stx-converting phage can expand the Stx-producing population in a human or animal host, and phage infection has been shown to modulate virulence in vitro and in vivo. Acellular factors, particularly colicins and microcins, can kill O157:H7 cells but may also trigger Stx expression in the process. Colicins, microcins, and other bacteriocins have diverse cellular targets, and many such molecules remain uncharacterized. The identification of additional Stx-amplifying microbial interactions will improve our understanding of E. coli O157:H7 infections and help elucidate the intricate regulation of pathogenicity in EHEC strains.

scholarly journals Replication of plasmids derived from Shiga toxin-converting bacteriophages in starved Escherichia coli

Microbiology ◽  
2011 ◽  
Vol 157 (1) ◽  
pp. 220-233 ◽  
Author(s):  
Bożena Nejman ◽  
Beata Nadratowska-Wesołowska ◽  
Agnieszka Szalewska-Pałasz ◽  
Alicja Węgrzyn ◽  
Grzegorz Węgrzyn
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Transcriptional Activation ◽  
Stringent Response ◽  
Toxin Production ◽  
Replication Initiation ◽  
Host Cells ◽  
Regulation Of Transcription ◽  
E Coli ◽  
Dna Replication Initiation

The pathogenicity of Shiga toxin-producing Escherichia coli (STEC) depends on the expression of stx genes that are located on lambdoid prophages. Effective toxin production occurs only after prophage induction, and one may presume that replication of the phage genome is important for an increase in the dosage of stx genes, positively influencing their expression. We investigated the replication of plasmids derived from Shiga toxin (Stx)-converting bacteriophages in starved E. coli cells, as starvation conditions may be common in the intestine of infected humans. We found that, unlike plasmids derived from bacteriophage λ, the Shiga toxin phage-derived replicons did not replicate in amino acid-starved relA + and relA − cells (showing the stringent and relaxed responses to starvation, respectively). The presence of the stable fraction of the replication initiator O protein was detected in all tested replicons. However, while ppGpp, the stringent response effector, inhibited the activities of the λ P R promoter and its homologues from Shiga toxin-converting bacteriophages, these promoters, except for λ P R, were only weakly stimulated by the DksA protein. We suggest that this less efficient (relative to λ) positive regulation of transcription responsible for transcriptional activation of the origin contributes to the inhibition of DNA replication initiation of Shiga toxin-converting bacteriophages in starved host cells, even in the absence of ppGpp (as in starved relA − hosts). Possible clinical implications of these results are discussed.

scholarly journals Adaptation in a Mouse Colony Monoassociated with Escherichia coli K-12 for More than 1,000 Days

2010 ◽  
Vol 76 (14) ◽  
pp. 4655-4663 ◽  
Author(s):  
Sean M. Lee ◽  
Aaron Wyse ◽  
Aaron Lesher ◽  
Mary Lou Everett ◽  
Linda Lou ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rates ◽  
Bacterial Species ◽  
Intestinal Flora ◽  
Average Density ◽  
Host Bacterium ◽  
E Coli ◽  
K 12

ABSTRACT Although mice associated with a single bacterial species have been used to provide a simple model for analysis of host-bacteria relationships, bacteria have been shown to display adaptability when grown in a variety of novel environments. In this study, changes associated with the host-bacterium relationship in mice monoassociated with Escherichia coli K-12 over a period of 1,031 days were evaluated. After 80 days, phenotypic diversification of E. coli was observed, with the colonizing bacteria having a broader distribution of growth rates in the laboratory than the parent E. coli. After 1,031 days, which included three generations of mice and an estimated 20,000 generations of E. coli, the initially homogeneous bacteria colonizing the mice had evolved to have widely different growth rates on agar, a potential decrease in tendency for spontaneous lysis in vivo, and an increased tendency for spontaneous lysis in vitro. Importantly, mice at the end of the experiment were colonized at an average density of bacteria that was more than 3-fold greater than mice colonized on day 80. Evaluation of selected isolates on day 1,031 revealed unique restriction endonuclease patterns and differences between isolates in expression of more than 10% of the proteins identified by two-dimensional electrophoresis, suggesting complex changes underlying the evolution of diversity during the experiment. These results suggest that monoassociated mice might be used as a tool for characterizing niches occupied by the intestinal flora and potentially as a method of targeting the evolution of bacteria for applications in biotechnology.

scholarly journals Shiga Toxin Gene Loss and Transfer In Vitro and In Vivo during Enterohemorrhagic Escherichia coli O26 Infection in Humans

2007 ◽  
Vol 73 (10) ◽  
pp. 3144-3150 ◽  
Author(s):  
Martina Bielaszewska ◽  
Rita Prager ◽  
Robin Köck ◽  
Alexander Mellmann ◽  
Wenlan Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Gene Loss ◽  
Pulsed Field Gel Electrophoresis ◽  
Enterohemorrhagic Escherichia Coli ◽  
Toxin Gene ◽  
Shiga Toxins ◽  
E Coli

ABSTRACT Escherichia coli serogroup O26 consists of enterohemorrhagic E. coli (EHEC) and atypical enteropathogenic E. coli (aEPEC). The former produces Shiga toxins (Stx), major determinants of EHEC pathogenicity, encoded by bacteriophages; the latter is Stx negative. We have isolated EHEC O26 from patient stools early in illness and aEPEC O26 from stools later in illness, and vice versa. Intrapatient EHEC and aEPEC isolates had quite similar pulsed-field gel electrophoresis (PFGE) patterns, suggesting that they might have arisen by conversion between the EHEC and aEPEC pathotypes during infection. To test this hypothesis, we asked whether EHEC O26 can lose stx genes and whether aEPEC O26 can be lysogenized with Stx-encoding phages from EHEC O26 in vitro. The stx 2 loss associated with the loss of Stx2-encoding phages occurred in 10% to 14% of colonies tested. Conversely, Stx2- and, to a lesser extent, Stx1-encoding bacteriophages from EHEC O26 lysogenized aEPEC O26 isolates, converting them to EHEC strains. In the lysogens and EHEC O26 donors, Stx2-converting bacteriophages integrated in yecE or wrbA. The loss and gain of Stx-converting bacteriophages diversifies PFGE patterns; this parallels findings of similar but not identical PFGE patterns in the intrapatient EHEC and aEPEC O26 isolates. EHEC O26 and aEPEC O26 thus exist as a dynamic system whose members undergo ephemeral interconversions via loss and gain of Stx-encoding phages to yield different pathotypes. The suggested occurrence of this process in the human intestine has diagnostic, clinical, epidemiological, and evolutionary implications.

scholarly journals VapC-1 of Nontypeable Haemophilus influenzae Is a Ribonuclease

2007 ◽  
Vol 189 (14) ◽  
pp. 5041-5048 ◽  
Author(s):  
Dayle A. Daines ◽  
Mack H. Wu ◽  
Sarah Y. Yuan
Keyword(s):  
Haemophilus Influenzae ◽  
Growth Inhibition ◽  
Gene Pair ◽  
Gene Families ◽  
Upper Respiratory Tract ◽  
Nontypeable Haemophilus Influenzae ◽  
E Coli ◽  
Conserved Gene

ABSTRACT Nontypeable Haemophilus influenzae (NTHi) organisms are obligate parasites of the human upper respiratory tract that can exist as commensals or pathogens. Toxin-antitoxin (TA) loci are highly conserved gene pairs that encode both a toxin and antitoxin moiety. Seven TA gene families have been identified to date, and NTHi carries two alleles of the vapBC family. Here, we have characterized the function of one of the NTHi alleles, vapBC-1. The gene pair is transcribed as an operon in two NTHi clinical isolates, and promoter fusions display an inverse relationship to culture density. The antitoxin VapB-1 forms homomultimers both in vitro and in vivo. The expression of the toxin VapC-1 conferred growth inhibition to an Escherichia coli expression strain and was successfully purified only when cloned in tandem with its cognate antitoxin. Using total RNA isolated from both E. coli and NTHi, we show for the first time that VapC-1 is an RNase that is active on free RNA but does not degrade DNA in vitro. Preincubation of the purified toxin and antitoxin together results in the formation of a protein complex that abrogates the activity of the toxin. We conclude that the NTHi vapBC-1 gene pair functions as a classical TA locus and that the induction of VapC-1 RNase activity leads to growth inhibition via the mechanism of mRNA cleavage.

scholarly journals Speed fluctuations of bacterial replisomes

2021 ◽  
Author(s):  
Deepak Bhat ◽  
Samuel Hauf ◽  
Charles Plessy ◽  
Yohei Yokobayashi ◽  
Simone Pigolotti
Keyword(s):  
Bacterial Population ◽  
Protein Complexes ◽  
Bacterial Species ◽  
Abundance Distribution ◽  
E Coli ◽  
Speed Error ◽  
Different Temperatures ◽  
Speed Fluctuations ◽  
Speed And Accuracy

Replisomes are multi-protein complexes that replicate genomes with remarkable speed and accuracy. Despite their importance, the dynamics of replisomes along the genome is poorly characterised, especially in vivo. In this paper, we link the replisome dynamics with the DNA abundance distribution measured in an exponentially growing bacterial population. Our approach permits to accurately infer the replisome dynamics along the genome from deep sequencing measurements. As an application, we experimentally measured the DNA abundance distribution in Escherichia coli populations growing at different temperatures. We find that the average replisome speed increases nearly five-fold between 17°C and 37°C. Further, we observe wave-like variations of the replisome speed along the genome. These variations are correlated with previously observed variations of the mutation rate along the genome. We interpret this correlation as a speed--error trade-off and discuss its possible dynamical origin. Our approach has the potential to elucidate replication dynamics in E. coli mutants and in other bacterial species.

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