scholarly journals The Small RNA RyhB Contributes to Siderophore Production and Virulence of Uropathogenic Escherichia coli

2014 ◽  
Vol 82 (12) ◽  
pp. 5056-5068 ◽  
Author(s):  
Gaëlle Porcheron ◽  
Rima Habib ◽  
Sébastien Houle ◽  
Mélissa Caza ◽  
François Lépine ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Urinary Tract ◽  
Type Strain ◽  
Iron Homeostasis ◽  
Wild Type Strain ◽  
Iron Acquisition ◽  
Wild Type ◽  
Content Type ◽  
E Coli

ABSTRACTInEscherichia coli, the small regulatory noncoding RNA (sRNA) RyhB and the global ferric uptake regulator (Fur) mediate iron acquisition and storage control. Iron is both essential and potentially toxic for most living organisms, making the precise maintenance of iron homeostasis necessary for survival. While the roles of these regulators in iron homeostasis have been well studied in a nonpathogenicE. colistrain, their impact on the production of virulence-associated factors is still unknown for a pathogenicE. colistrain. We thus investigated the roles of RyhB and Fur in iron homeostasis and virulence of the uropathogenicE. coli(UPEC) strain CFT073. In a murine model of urinary tract infection (UTI), deletion offuralone did not attenuate virulence, whereas a ΔryhBmutant and a ΔfurΔryhBdouble mutant showed significantly reduced bladder colonization. The Δfurmutant was more sensitive to oxidative stress and produced more of the siderophores enterobactin, salmochelins, and aerobactin than the wild-type strain. In contrast, while RyhB was not implicated in oxidative stress resistance, the ΔryhBmutant produced lower levels of siderophores. This decrease was correlated with the downregulation ofshiA(encoding a transporter of shikimate, a precursor of enterobactin and salmochelin biosynthesis) andiucD(involved in aerobactin biosynthesis) in this mutant grown in minimal medium or in human urine.iucDwas also downregulated in bladders infected with the ΔryhBmutant compared to those infected with the wild-type strain. Our results thus demonstrate that the sRNA RyhB is involved in production of iron acquisition systems and colonization of the urinary tract by pathogenicE. coli.

scholarly journals Genetic Analysis of the Role ofyfiRin the Ability of Escherichia coli CFT073 To Control Cellular Cyclic Dimeric GMP Levels and To Persist in the Urinary Tract

2013 ◽  
Vol 81 (9) ◽  
pp. 3089-3098 ◽  
Author(s):  
Erica L. Raterman ◽  
Daniel D. Shapiro ◽  
Daniel J. Stevens ◽  
Kevin J. Schwartz ◽  
Rodney A. Welch
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Cellulose Production ◽  
Content Type ◽  
E Coli ◽  
Successful Infection ◽  
Tract Infections

ABSTRACTDuring urinary tract infections (UTIs), uropathogenicEscherichia colimust maintain a delicate balance between sessility and motility to achieve successful infection of both the bladder and kidneys. Previous studies showed that cyclic dimeric GMP (c-di-GMP) levels aid in the control of the transition between motile and nonmotile states inE. coli. TheyfiRNBlocus inE. coliCFT073 contains genes for YfiN, a diguanylate cyclase, and its activity regulators, YfiR and YfiB. Deletion ofyfiRyielded a mutant that was attenuated in both the bladder and the kidneys when tested in competition with the wild-type strain in the murine model of UTI. A doubleyfiRNmutant was not attenuated in the mouse model, suggesting that unregulated YfiN activity and likely increased cytoplasmic c-di-GMP levels cause a survival defect. Curli fimbriae and cellulose production were increased in theyfiRmutant. Expression ofyhjH, a gene encoding a proven phosphodiesterase, in CFT073 ΔyfiRsuppressed the overproduction of curli fimbriae and cellulose and further verified that deletion ofyfiRresults in c-di-GMP accumulation. Additional deletion ofcsgDandbcsA, genes necessary for curli fimbriae and cellulose production, respectively, returned colonization levels of theyfiRdeletion mutant to wild-type levels. Peroxide sensitivity assays and iron acquisition assays displayed no significant differences between theyfiRmutant and the wild-type strain. These results indicate that dysregulation of c-di-GMP production results in pleiotropic effects that disableE. coliin the urinary tract and implicate the c-di-GMP regulatory system as an important factor in the persistence of uropathogenicE. coli in vivo.

scholarly journals Fumarate-Mediated Persistence of Escherichia coli against Antibiotics

2016 ◽  
Vol 60 (4) ◽  
pp. 2232-2240 ◽  
Author(s):  
Jun-Seob Kim ◽  
Da-Hyeong Cho ◽  
Paul Heo ◽  
Suk-Chae Jung ◽  
Myungseo Park ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Molecular Mechanisms ◽  
Wild Type Strain ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
Quiescent Cells ◽  
Transport Chain ◽  
Genetic Perturbations

ABSTRACTBacterial persisters are a small fraction of quiescent cells that survive in the presence of lethal concentrations of antibiotics. They can regrow to give rise to a new population that has the same vulnerability to the antibiotics as did the parental population. Although formation of bacterial persisters in the presence of various antibiotics has been documented, the molecular mechanisms by which these persisters tolerate the antibiotics are still controversial. We found that amplification of the fumarate reductase operon (FRD) inEscherichia coliled to a higher frequency of persister formation. The persister frequency ofE. coliwas increased when the cells contained elevated levels of intracellular fumarate. Genetic perturbations of the electron transport chain (ETC), a metabolite supplementation assay, and even the toxin-antitoxin-relatedhipA7mutation indicated that surplus fumarate markedly elevated theE. colipersister frequency. AnE. colistrain lacking succinate dehydrogenase (SDH), thereby showing a lower intracellular fumarate concentration, was killed ∼1,000-fold more effectively than the wild-type strain in the stationary phase. It appears thatSDHandFRDrepresent a paired system that gives rise to and maintainsE. colipersisters by producing and utilizing fumarate, respectively.

scholarly journals The Gene yggE Functions in Restoring Physiological Defects of Escherichia coli Cultivated under Oxidative Stress Conditions

2005 ◽  
Vol 71 (5) ◽  
pp. 2762-2765 ◽  
Author(s):  
SunYoung Kim ◽  
Motomu Nishioka ◽  
Shuhei Hayashi ◽  
Hiroyuki Honda ◽  
Takeshi Kobayashi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Specific Growth ◽  
Maximum Specific Growth Rate ◽  
Oxygen Species ◽  
Wild Type ◽  
Amino Acid Requirement ◽  
E Coli

ABSTRACT DNA microarray analysis showed that yfiD, yggB, and yggE genes were up-regulated when superoxide dismutase (SOD)-deficient Escherichia coli IM303 (I4) was cultivated under the oxidative stress generated by photoexcited TiO2, and pYFD, pYGB, and pYGE were constructed by inserting the respective genes into a pUC 19 vector. The content of reactive oxygen species (ROS) in IM303 (I4) cells carrying pYGE was reduced to 31% of ROS content in the control cells with pUC 19. In the culture of wild-type strain, E. coli MM294, in the medium with paraquat (10 μmol/l), maximum specific growth rate of the cells with pYGE was about five times higher than that of the control cells, with a decreased ROS content in the former cells. The introduction of pYGE also suppressed the occurrence of the cells with altered amino acid requirement in the culture of MM294 cells with paraquat.

scholarly journals The CreC Regulator of Escherichia coli, a New Target for Metabolic Manipulations

2015 ◽  
Vol 82 (1) ◽  
pp. 244-254 ◽  
Author(s):  
Manuel S. Godoy ◽  
Pablo I. Nikel ◽  
José G. Cabrera Gomez ◽  
M. Julia Pettinari
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Oxygen Availability ◽  
Biochemical Network ◽  
Metabolic Effects ◽  
Null Mutant ◽  
Wild Type ◽  
Content Type ◽  
E Coli

ABSTRACTThe CreBC (carbon source-responsive) two-component regulation system ofEscherichia coliaffects a number of functions, including intermediary carbon catabolism. The impacts of differentcreCmutations (a ΔcreCmutant and a mutant carrying the constitutivecreC510allele) on bacterial physiology were analyzed in glucose cultures under three oxygen availability conditions. Differences in the amounts of extracellular metabolites produced were observed in the null mutant compared to the wild-type strain and the mutant carryingcreC510and shown to be affected by oxygen availability. The ΔcreCstrain secreted more formate, succinate, and acetate but less lactate under low aeration. These metabolic changes were associated with differences in AckA and LdhA activities, both of which were affected by CreC. Measurement of the NAD(P)H/NAD(P)+ratios showed that thecreC510strain had a more reduced intracellular redox state, while the opposite was observed for the ΔcreCmutant, particularly under intermediate oxygen availability conditions, indicating that CreC affects redox balance. The null mutant formed more succinate than the wild-type strain under both low aeration and no aeration. Overexpression of the genes encoding phosphoenolpyruvate carboxylase fromE. coliand a NADH-forming formate dehydrogenase fromCandida boidiniiin the ΔcreCmutant further increased the yield of succinate on glucose. Interestingly, the elimination ofackAandadhEdid not significantly improve the production of succinate. The diverse metabolic effects of this regulator on the central biochemical network ofE. colimake it a good candidate for metabolic-engineering manipulations to enhance the formation of bioproducts, such as succinate.

scholarly journals Finding Regulators Associated with the Expression of the Long Polar Fimbriae in Enteropathogenic Escherichia coli

2015 ◽  
Vol 197 (23) ◽  
pp. 3658-3665 ◽  
Author(s):  
Jia Hu ◽  
Brittany N. Ross ◽  
Roberto J. Cieza ◽  
Alfredo G. Torres
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
Colonization Factor ◽  
Initial Adhesion ◽  
Intestinal Adhesion

ABSTRACTEnteropathogenicEscherichia coli(EPEC) is a human pathogen that requires initial adhesion to the intestine in order to cause disease. Multiple adhesion factors have been identified inE. colistrains, among them the long polar fimbriae (Lpf), a colonization factor associated with intestinal adhesion. The conditions of Lpf expression are well understood in enterohemorrhagicE. coli(EHEC); however, the expression of EPEClpfhas been found to be repressed under anyin vitrocondition tested. Therefore, we decided to identify those factors silencing expression of EPEClpf. Because histone-like nucleoid structuring protein (H-NS) is a known repressor of EHEClpf, we tested it and found that H-NS is a repressor of EPEClpf. We also found that the adhesion of the EPEC Δhnsstrain was significantly enhanced compared to the wild-type strain. Becauselpfexpression was modestly increased in thehnsmutant, transposon mutagenesis was performed to find a strain displaying higherlpfexpression than EPEC Δhns. One Tn5insertion was identified within theyhjXgene, and furtherin vitrocharacterization revealed increasedlpfexpression and adhesion to Caco-2 cells compared with EPEC Δhns. However, in a murine model of intestinal infection, the EPEC Δhnsand EPEC ΔhnsTn5mutants had only a slight change in colonization pattern compared to the wild-type strain. Our data showed that EPEC Lpf is transcribed, but its role in EPEC intestinal colonization requires further analysis.IMPORTANCEData are presented demonstrating that the long polar fimbriae (lpf) operon in enteropathogenicE. coli(EPEC) is highly regulated; however, derepression occurs by mutagenizing two proteins associated with its control. The study demonstrates that the EPEClpfoperon can be expressed and, therefore, participates in the EPEC adherence phenotype.

scholarly journals Quorum Sensing Is a Global Regulatory Mechanism in Enterohemorrhagic Escherichia coli O157:H7

2001 ◽  
Vol 183 (17) ◽  
pp. 5187-5197 ◽  
Author(s):  
Vanessa Sperandio ◽  
Alfredo G. Torres ◽  
Jorge A. Girón ◽  
James B. Kaper
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Type Strain ◽  
Wild Type Strain ◽  
Regulatory Mechanism ◽  
Sos Response ◽  
Enterohemorrhagic Escherichia Coli ◽  
Trna Genes ◽  
Wild Type ◽  
E Coli

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is responsible for outbreaks of bloody diarrhea and hemolytic-uremic syndrome in many countries. EHEC virulence mechanisms include the production of Shiga toxins (Stx) and formation of attaching and effacing (AE) lesions on intestinal epithelial cells. We recently reported that genes involved in the formation of the AE lesion were regulated by quorum sensing through autoinducer-2, which is synthesized by the product of the luxS gene. In this study we hybridized an E. coli gene array with cDNA synthesized from RNA that was extracted from EHEC strain 86-24 and its isogenicluxS mutant. We observed that 404 genes were regulated by luxS at least fivefold, which comprises approximately 10% of the array genes; 235 of these genes were up-regulated and 169 were down-regulated in the wild-type strain compared to in theluxS mutant. Down-regulated genes included several involved in cell division, as well as ribosomal and tRNA genes. Consistent with this pattern of gene expression, theluxS mutant grows faster than the wild-type strain (generation times of 37.5 and 60 min, respectively, in Dulbecco modified Eagle medium). Up-regulated genes included several involved in the expression and assembly of flagella, motility, and chemotaxis. Using operon::lacZ fusions to class I, II, and III flagellar genes, we were able to confirm this transcriptional regulation. We also observed fewer flagella by Western blotting and electron microscopy and decreased motility halos in semisolid agar in the luxS mutant. The average swimming speeds for the wild-type strain and the luxS mutant are 12.5 and 6.6 μm/s, respectively. We also observed an increase in the production of Stx due to quorum sensing. Genes encoding Stx, which are transcribed along with λ-like phage genes, are induced by an SOS response, and genes involved in the SOS response were also regulated by quorum sensing. These results indicate that quorum sensing is a global regulatory mechanism for basic physiological functions of E. coli as well as for virulence factors.

scholarly journals RpoS Contributes to Phagocyte Oxidase-Mediated Stress Resistance during Urinary Tract Infection by Escherichia coli CFT073

mBio ◽  
2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Andrew J. Hryckowian ◽  
Rodney A. Welch
Keyword(s):  
Oxidative Stress ◽  
Urinary Tract ◽  
Wild Type ◽  
Upec Strain ◽  
Content Type ◽  
General Stress Response ◽  
E Coli ◽  
Phagocyte Oxidase ◽  
Strain Cft073 ◽  
K 12

ABSTRACTUropathogenicEscherichia coli(UPEC) is the most common causative agent of community-acquired urinary tract infection (UTI). In order to cause UTI, UPEC must endure stresses ranging from nutrient limitation to host immune components. RpoS (σS), the general stress response sigma factor, directs gene expression under a variety of inhibitory conditions. Our study ofrpoSin UPEC strain CFT073 began after we discovered anrpoS-frameshift mutation in one of our laboratory stocks of “wild-type” CFT073. We demonstrate that anrpoS-deletion mutation in CFT073 leads to a colonization defect during UTI of CBA/J mice at 48 hours postinfection (hpi). There is no difference between the growth rates of CFT073 and CFT073rpoSin urine. This indicates thatrpoSis needed for replication and survival in the host rather than being needed to address limitations imposed by urine nutrients. Consistent with previous observations inE. coliK-12, CFT073rpoSis more sensitive to oxidative stress than the wild type. We demonstrate that peroxide levels are elevated in voided urine from CFT073-infected mice compared to urine from mock-infected mice, which supports the notion that oxidative stress is generated by the host in response to UPEC. In mice that lack phagocyte oxidase, the enzyme complex expressed by phagocytes that produces superoxide, the competitive defect of CFT073rpoSin bladder colonization is lost. These results demonstrate that σSis important for UPEC survival under conditions of phagocyte oxidase-generated stress during UTI. Though σSaffects the pathogenesis of other bacterial species, this is the first work that directly implicates σSas important for UPEC pathogenesis.IMPORTANCEUPEC must cope with a variety of stressful conditions in the urinary tract during infection. RpoS (σS), the general stress response sigma factor, is known to direct the expression of many genes under a variety of stressful conditions in laboratory-adaptedE. coliK-12. Here, we show that σSis needed by the model UPEC strain CFT073 to cope with oxidative stress provided by phagocytes during infection. These findings represent the first report that implicates σSin the fitness of UPEC during infection and support the idea of the need for a better understanding of the effects of this global regulator of gene expression during UTI.

scholarly journals Sml1 Inhibits the DNA Repair Activity of Rev1 in Saccharomyces cerevisiae during Oxidative Stress

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Rui Yao ◽  
Pei Zhou ◽  
Chengjin Wu ◽  
Liming Liu ◽  
Jing Wu
Keyword(s):  
Oxidative Stress ◽  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Survival Rate ◽  
Type Strain ◽  
Mutation Frequency ◽  
Wild Type Strain ◽  
Yeast Cells ◽  
Wild Type ◽  
Content Type

ABSTRACT In Saccharomyces cerevisiae, Y family DNA polymerase Rev1 is involved in the repair of DNA damage by translesion DNA synthesis (TLS). In the current study, to elucidate the role of Rev1 in oxidative stress-induced DNA damage in S. cerevisiae, REV1 was deleted and overexpressed; transcriptome analysis of these mutants along with the wild-type strain was performed to screen potential genes that could be associated with REV1 during response to DNA damage. When the yeast cells were treated with 2 mM H2O2, the deletion of REV1 resulted in a 1.5- and 2.8-fold decrease in the survival rate and mutation frequency, respectively, whereas overexpression of REV1 increased the survival rate and mutation frequency by 1.1- and 2.9-fold, respectively, compared to the survival rate and mutation frequency of the wild-type strain. Transcriptome and phenotypic analyses identified that Sml1 aggravated oxidative stress in the yeast cells by inhibiting the activity of Rev1. This inhibition was due to the physical interaction between the BRCA1 C terminus (BRCT) domain of Rev1 and amino acid residues 36 to 70 of Sml1; the cell survival rate and mutation frequency increased by 1.8- and 3.1-fold, respectively, when this interaction was blocked. We also found that Sml1 inhibited Rev1 phosphorylation under oxidative stress and that deletion of SML1 increased the phosphorylation of Rev1 by 46%, whereas overexpression of SML1 reduced phosphorylation of Rev1. Overall, these findings demonstrate that Sml1 could be a novel regulator that mediates Rev1 dephosphorylation to inhibit its activity during oxidative stress. IMPORTANCE Rev1 was critical for cell growth in S. cerevisiae, and the deletion of REV1 caused a severe growth defect in cells exposed to oxidative stress (2 mM H2O2). Furthermore, we found that Sml1 physically interacted with Rev1 and inhibited Rev1 phosphorylation, thereby inhibiting Rev1 DNA antioxidant activity. These findings indicate that Sml1 could be a novel regulator for Rev1 in response to DNA damage by oxidative stress.

scholarly journals The RcsCB His-Asp Phosphorelay System Is Essential To Overcome Chlorpromazine-Induced Stress in Escherichia coli

2002 ◽  
Vol 184 (10) ◽  
pp. 2850-2853 ◽  
Author(s):  
Annie Conter ◽  
Rachel Sturny ◽  
Claude Gutierrez ◽  
Kaymeuang Cam
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Cell Envelope ◽  
Wild Type ◽  
E Coli ◽  
Induced Stress ◽  
Mutant Strains ◽  
Molecular Nature

ABSTRACT The RcsCB His-Asp phosphorelay system regulates the expression of several genes of Escherichia coli, but the molecular nature of the inducing signal is still unknown. We show here that treatment of an exponentially growing culture of E. coli with the cationic amphipathic compound chlorpromazine (CPZ) stimulates expression of a set of genes positively regulated by the RcsCB system. This induction is abolished in rcsB or rcsC mutant strains. In addition, treatment with CPZ inhibits growth. The wild-type strain is able to recover from this inhibition and resume growth after a period of adaptation. In contrast, strains deficient in the RcsCB His-Asp phosphorelay system are hypersensitive to CPZ. These results suggest that cells must express specific RcsCB-regulated genes in order to cope with the CPZ-induced stress. This is the first report of the essential role of the RcsCB system in a stress situation. These results also strengthen the notion that alterations of the cell envelope induce a signal recognized by the RcsC sensor.

scholarly journals Expression of Different-Size Transcripts from theclpP-clpX Operon of Escherichia coli during Carbon Deprivation

2000 ◽  
Vol 182 (23) ◽  
pp. 6630-6637 ◽  
Author(s):  
Chin Li ◽  
Yi Ping Tao ◽  
Lee D. Simon
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Type Strain ◽  
Wild Type Strain ◽  
Transcription Termination ◽  
Carbon Starvation ◽  
Lower Percentage ◽  
Wild Type ◽  
Lower Efficiency ◽  
E Coli

ABSTRACT Transcription of the clpP-clpX operon ofEscherichia coli leads to the production of two different sizes of transcripts. In log phase, the level of the longer transcript is higher than the level of the shorter transcript. Soon after the onset of carbon starvation, the level of the shorter transcript increases significantly, and the level of the longer transcript decreases. The longer transcript consists of the entireclpP-clpX operon, whereas the shorter transcript contains the entire clpP gene but none of the clpXcoding sequence. The RpoH protein is required for the increase in the level of the shorter transcript during carbon starvation. Primer extension experiments suggest that there is increased usage of the ς32-dependent promoter of the clpP-clpXoperon within 15 min after the start of carbon starvation. Expression of the clpP-clpX operon from the promoters upstream of theclpP gene decreases to a very low level by 20 min after the onset of carbon starvation. Various pieces of evidence suggest, though they do not conclusively prove, that production of the shorter transcript may involve premature termination of the longer transcript. The half-life of the shorter transcript is much less than that of the longer transcript during carbon starvation. E. coli rpoBmutations that affect transcription termination efficiency alter the ratio of the shorter clpP-clpX transcript to the longer transcript. The E. coli rpoB3595 mutant, with an RNA polymerase that terminates transcription with lower efficiency than the wild type, accumulates a lower percentage of the shorter transcript during carbon starvation than does the isogenic wild-type strain. In contrast, the rpoB8 mutant, with an RNA polymerase that terminates transcription with higher efficiency than the wild type, produces a higher percentage of the shorter clpP-clpXtranscript when E. coli is in log phase. These and other data are consistent with the hypothesis that the shorter transcript results from premature transcription termination during production of the longer transcript.

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