scholarly journals A long-term epigenetic memory switch controls bacterial virulence bimodality

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Irine Ronin ◽  
Naama Katsowich ◽  
Ilan Rosenshine ◽  
Nathalie Q Balaban
Keyword(s):  
Mathematical Modeling ◽  
Virulence Genes ◽  
Phenotypic Variability ◽  
Bacterial Virulence ◽  
Environmental Cues ◽  
Human Pathogen ◽  
Epigenetic Memory ◽  
E Coli

When pathogens enter the host, sensing of environmental cues activates the expression of virulence genes. Opposite transition of pathogens from activating to non-activating conditions is poorly understood. Interestingly, variability in the expression of virulence genes upon infection enhances colonization. In order to systematically detect the role of phenotypic variability in enteropathogenic E. coli (EPEC), an important human pathogen, both in virulence activating and non-activating conditions, we employed the ScanLag methodology. The analysis revealed a bimodal growth rate. Mathematical modeling combined with experimental analysis showed that this bimodality is mediated by a hysteretic memory-switch that results in the stable co-existence of non-virulent and hyper-virulent subpopulations, even after many generations of growth in non-activating conditions. We identified the per operon as the key component of the hysteretic switch. This unique hysteretic memory switch may result in persistent infection and enhanced host-to-host spreading.

DNA methylation in Yersinia enterocolitica: role of the DNA adenine methyltransferase in mismatch repair and regulation of virulence factors

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2291-2299 ◽  
Author(s):  
Stefan Fälker ◽  
M. Alexander Schmidt ◽  
Gerhard Heusipp
Keyword(s):  
Mismatch Repair ◽  
Yersinia Enterocolitica ◽  
Virulence Genes ◽  
Spontaneous Mutation ◽  
Gram Negative Bacteria ◽  
E Coli ◽  
Physiological Processes ◽  
Dna Adenine Methyltransferase

DNA adenine methyltransferase (Dam) plays an important role in physiological processes of Gram-negative bacteria such as mismatch repair and replication. In addition, Dam regulates the expression of virulence genes in various species. The authors cloned the dam gene of Yersinia enterocolitica and showed that Dam is essential for viability. Dam overproduction in Y. enterocolitica resulted in an increased frequency of spontaneous mutation and decreased resistance to 2-aminopurine; however, these effects were only marginal compared to the effect of overproduction of Escherichia coli-derived Dam in Y. enterocolitica, implying different roles or activities of Dam in mismatch repair of the two species. These differences in Dam function are not the cause for the essentiality of Dam in Y. enterocolitica, as Dam of E. coli can complement a dam defect in Y. enterocolitica. Instead, Dam seems to interfere with expression of essential genes. Furthermore, Dam mediates virulence of Y. enterocolitica. Dam overproduction results in increased tissue culture invasion of Y. enterocolitica, while the expression of specifically in vivo-expressed genes is not altered.

scholarly journals Plasmid DNA Supercoiling and Survival in Long-Term Cultures of Escherichia coli: Role of NaCl

2003 ◽  
Vol 185 (17) ◽  
pp. 5324-5327 ◽  
Author(s):  
Annie Conter
Keyword(s):  
Escherichia Coli ◽  
Dna Supercoiling ◽  
Luria Bertani ◽  
Plasmid Pbr322 ◽  
E Coli ◽  
Topological State ◽  
Negative Supercoiling ◽  
The Relationship

ABSTRACT The relationship between the survival of Escherichia coli during long-term starvation in rich medium and the supercoiling of a reporter plasmid (pBR322) has been studied. In aerated continuously shaken cultures, E. coli lost the ability to form colonies earlier in rich NaCl-free Luria-Bertani medium than in NaCl-containing medium, and the negative supercoiling of plasmid pBR322 declined more rapidly in the absence of NaCl. Addition of NaCl at the 24th hour restored both viability and negative supercoiling in proportion to the concentration of added NaCl. Addition of ofloxacin, a quinolone inhibitor of gyrase, abolished rescue by added NaCl in proportion to the ofloxacin added. This observation raises the possibility that cells had the ability to recover plasmid supercoiling even if nutrients were not available and could survive during long-term starvation in a manner linked, at least in part, to the topological state of DNA and gyrase activity.

scholarly journals Escherichia coli EDL933 Requires Gluconeogenic Nutrients To Successfully Colonize the Intestines of Streptomycin-Treated Mice Precolonized with E. coli Nissle 1917

2015 ◽  
Vol 83 (5) ◽  
pp. 1983-1991 ◽  
Author(s):  
Silvia A. C. Schinner ◽  
Matthew E. Mokszycki ◽  
Jimmy Adediran ◽  
Mary Leatham-Jensen ◽  
Tyrrell Conway ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Genes ◽  
Probiotic Strain ◽  
Content Type ◽  
E Coli ◽  
Link Type ◽  
Mouse Intestine ◽  
K 12 ◽  
Rule Out

Escherichia coliMG1655, a K-12 strain, uses glycolytic nutrients exclusively to colonize the intestines of streptomycin-treated mice when it is the onlyE. colistrain present or when it is confronted withE. coliEDL933, an O157:H7 strain. In contrast,E. coliEDL933 uses glycolytic nutrients exclusively when it is the onlyE. colistrain in the intestine but switches in part to gluconeogenic nutrients when it colonizes mice precolonized withE. coliMG1655 (R. L. Miranda et al., Infect Immun 72:1666–1676, 2004,http://dx.doi.org/10.1128/IAI.72.3.1666-1676.2004). Recently, J. W. Njoroge et al. (mBio 3:e00280-12, 2012,http://dx.doi.org/10.1128/mBio.00280-12) reported thatE. coli86-24, an O157:H7 strain, activates the expression of virulence genes under gluconeogenic conditions, suggesting that colonization of the intestine with a probioticE. colistrain that outcompetes O157:H7 strains for gluconeogenic nutrients could render them nonpathogenic. Here we report thatE. coliNissle 1917, a probiotic strain, uses both glycolytic and gluconeogenic nutrients to colonize the mouse intestine between 1 and 5 days postfeeding, appears to stop using gluconeogenic nutrients thereafter in a large, long-term colonization niche, but continues to use them in a smaller niche to compete with invadingE. coliEDL933. Evidence is also presented suggesting that invadingE. coliEDL933 uses both glycolytic and gluconeogenic nutrients and needs the ability to perform gluconeogenesis in order to colonize mice precolonized withE. coliNissle 1917. The data presented here therefore rule out the possibility thatE. coliNissle 1917 can starve the O157:H7E. colistrain EDL933 of gluconeogenic nutrients, even thoughE. coliNissle 1917 uses such nutrients to compete withE. coliEDL933 in the mouse intestine.

scholarly journals H-NS Controls pap and daaFimbrial Transcription in Escherichia coli in Response to Multiple Environmental Cues

2000 ◽  
Vol 182 (22) ◽  
pp. 6391-6400 ◽  
Author(s):  
Christine A. White-Ziegler ◽  
Anuradha Villapakkam ◽  
Karla Ronaszeki ◽  
Sarah Young
Keyword(s):  
Escherichia Coli ◽  
Low Temperature ◽  
Carbon Source ◽  
Iron Concentration ◽  
Environmental Cues ◽  
Rich Medium ◽  
High Osmolarity ◽  
E Coli ◽  
Transcriptional Fusions

ABSTRACT A comparative study was completed to determine the influence of various environmental stimuli on the transcription of three different fimbrial operons in Escherichia coli and to determine the role of the histone-like protein H-NS in this environmental regulation. The fimbrial operons studied included the pap operon, which encodes pyelonephritis-associated pili (P pili), the daaoperon, which encodes F1845 fimbriae, and the fan operon, which encodes K99 fimbriae. Using lacZYA transcriptional fusions within each of the fimbrial operons, we tested temperature, osmolarity, carbon source, rich medium, oxygen levels, pH, amino acids, solid medium, and iron concentration for their effects on fimbrial gene expression. Low temperature, high osmolarity, glucose as a carbon source, and rich medium repressed transcription of all three operons. High iron did not alter transcription of any of the operons tested, whereas the remaining stimuli had effects on individual operons. For the pap and daa operons, introduction of thehns651 mutation relieved the repression, either fully or partially, due to low temperature, glucose as a carbon source, rich medium, and high osmolarity. Taken together, these data indicate that there are common environmental cues that regulate fimbrial transcription in E. coli and that H-NS is an important environmental regulator for fimbrial transcription in response to several stimuli.

LABORATORY ERRORS FOR IDENTIFICATION OF THE ESCHERICHIA COLI STRAINS OF THE SEROLOGICAL GROUPS O6 AND O25 AS ACUTE INTESTINAL INFECTIONS

2020 ◽  
Vol 65 (6) ◽  
pp. 368-374
Author(s):  
Mariia A. Makarova ◽  
Zoya N. Matveeva ◽  
E. V. Smirnova ◽  
L. I. Semchenkova ◽  
I. A. Derevianchenko ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Virulence Genes ◽  
Beta Lactams ◽  
E Coli ◽  
Laboratory Errors ◽  
Intestinal Infections ◽  
Human Pathology ◽  
Genes Encoding ◽  
Stool Samples

Were studied the genes encoding the virulence factors of 221 strains: E. coli O6:H1 (194) and E. coli O25:H4 (27), isolated in 2014-2018 from stool samples of children and adults examined according to epidemic indications. Molecular methods included PCR with hybridization-fluorescence and electrophoresis detection of amplified products. The strains did not have virulence genes for diarrheagenic E. coli (DEC) pathogroups EPEC, ETEC, EIEC, EHEC, EAggEC, and belonged to the phylogenetic group B2. They contained from four to eight genes encoding virulence factors of ExPEC: E. coli O6:H1 - pap (68,6%), sfa (87,6%), fimH (96,4%), hly (62,4%), cnf (74,7%), iutA (97,9%), fyuA (95,9%), chu (100%); E. coli O25:H4 - pap (66,7%), afa (22,2%), fimH (100%), hly (44,4%), cnf (44,4%), iutA (100%) , fyuA (100%), chu (100%). The antimicrobial susceptibility testing to 6 classes of antimicrobials (beta-lactams, fluoroquinolones, aminoglycosides, nitrofurantoin, sulfanilamide, trimethoprim / sulfamethoxazole) according the EUCAST. 60,3% of E. coli O6:H1 were sensitive to antibiotics, E. coli O25:H4 remained sensitive to carbapenems and nitrofurans. Extended-spectrum cephalosporins resistance was due to the production ESBL (CTX-M). The 57,1% resistant strains of E. coli O6:H1 and 100% of E. coli O25:H4 strains belonged to the MDR phenotype. The XDR phenotype had one in five MDR strains of E. coli O6:H1 and E. coli O25:H4. All strains of E. coli O25:H4 belonged to ST131. Given the important role of E. coli in human pathology, detection of virulence genes should be performed to confirm the etiological significance of the isolated strain.

scholarly journals Cloning and Expression Analysis of One Gamma-Glutamylcysteine Synthetase Gene (Hbγ-ECS1) in Latex Production inHevea brasiliensis

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Wei Fang ◽  
Luo Shi Qiao ◽  
Wu Ming ◽  
Qiu Jian ◽  
Yang Wen Feng ◽  
...  
Keyword(s):  
Specific Activity ◽  
Rubber Tree ◽  
Natural Rubber Latex ◽  
Cloning And Expression ◽  
E Coli ◽  
Glutamylcysteine Synthetase ◽  
Commercial Source ◽  
Rate Limiting

Rubber tree is a major commercial source of natural rubber. Latex coagulation is delayed by thiols, which belong to the important type of antioxidants in laticifer submembrane, and is composed of glutathione (GSH), cysteine, and methionine. The rate-limiting enzyme,γ-ECS, plays an important role in regulating the biosynthesis of glutathione under any environment conditions. To understand the relation betweenγ-ECS and thiols and to correlate latex flow with one-time tapping and continuous tapping, we cloned and derived the full length of oneγ-ECS from rubber tree latex (Hbγ-ECS1). According to qPCR analysis, the expression levels ofHbγ-ECS1were induced by tapping and Ethrel stimulation, and the expression was related to thiols content in the latex. Continuous tapping induced injury, and the expression ofHbγECS1increased with routine tapping and Ethrel-stimulation tapping (more intensive tapping). According to expression in long-term flowing latex, the gene was related to the duration of latex flow.HbγECS1was expressed inE. coliRosetta using pET-sumo as an expression vector and the recombinant enzyme was purified; then we achieved 0.827 U/mg specific activity and about 66 kDa molecular weight. The present study can help us understand the complex role ofHbγ-ECSin thiols biosynthesis, which is influenced by tapping.

scholarly journals Author response: A long-term epigenetic memory switch controls bacterial virulence bimodality

2016 ◽  
Author(s):  
Irine Ronin ◽  
Naama Katsowich ◽  
Ilan Rosenshine ◽  
Nathalie Q Balaban
Keyword(s):  
Bacterial Virulence ◽  
Author Response ◽  
Epigenetic Memory

scholarly journals Mechanisms of DRA recycling in intestinal epithelial cells: effect of enteropathogenic E. coli

2015 ◽  
Vol 309 (12) ◽  
pp. C835-C846 ◽  
Author(s):  
Tarunmeet Gujral ◽  
Anoop Kumar ◽  
Shubha Priyamvada ◽  
Seema Saksena ◽  
Ravinder K. Gill ◽  
...  
Keyword(s):  
Virulence Genes ◽  
Surface Expression ◽  
Intestinal Epithelial ◽  
Basal Surface ◽  
Infantile Diarrhea ◽  
E Coli ◽  
Food Borne ◽  
Cell Surface Biotinylation ◽  
Exchange Activity

Enteropathogenic Escherichia coli (EPEC) is a food-borne pathogen that causes infantile diarrhea worldwide. EPEC decreases the activity and surface expression of the key intestinal Cl−/HCO3− exchanger SLC26A3 [downregulated in adenoma (DRA)], contributing to the pathophysiology of early diarrhea. Little is known about the mechanisms governing membrane recycling of DRA. In the current study, Caco-2 cells were used to investigate DRA trafficking under basal conditions and in response to EPEC. Apical Cl−/HCO3− exchange activity was measured as DIDS-sensitive 125I− uptake. Cell surface biotinylation was performed to assess DRA endocytosis and exocytosis. Inhibition of clathrin-mediated endocytosis by chlorpromazine (60 μM) increased apical Cl−/HCO3− exchange activity. Dynasore, a dynamin inhibitor, also increased function and surface levels of DRA via decreased endocytosis. Perturbation of microtubules by nocodazole revealed that intact microtubules are essential for basal exocytic (but not endocytic) DRA recycling. Mice treated with colchicine showed a decrease in DRA surface levels as visualized by confocal microscopy. In response to EPEC infection, DRA surface expression was reduced partly via an increase in DRA endocytosis and a decrease in exocytosis. These effects were dependent on the EPEC virulence genes espG1 and espG2. Intriguingly, the EPEC-induced decrease in DRA function was unaltered in the presence of dynasore, suggesting a clathrin-independent internalization of surface DRA. In conclusion, these studies establish the role of clathrin-mediated endocytosis and microtubules in the basal surface expression of DRA and demonstrate that the EPEC-mediated decrease in DRA function and apical expression in Caco-2 cells involves decreased exocytosis.

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