scholarly journals Survival of uropathogenic Escherichia coli in the murine urinary tract is dependent on OmpR

Microbiology ◽  
2009 ◽  
Vol 155 (6) ◽  
pp. 1832-1839 ◽  
Author(s):  
William R. Schwan
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Phosphorylation Site ◽  
Regulatory System ◽  
Growth Defect ◽  
Wild Type ◽  
Log Reduction

Uropathogenic Escherichia coli (UPEC) can grow in environments with significantly elevated osmolarities, such as murine and human urinary tracts. OmpR is the response regulator part of a two-component OmpR–EnvZ regulatory system that responds to osmotic stresses. To determine the role of OmpR in UPEC survival, a ΔompR mutant was created in the UPEC clinical isolate NU149. The ΔompR mutant had a growth defect compared with the wild-type strain under osmotic stress conditions; this defect was complemented by the full-length ompR gene on a plasmid, but not with a mutant OmpR with an alanine substitution for aspartic acid at the phosphorylation site at position 55. Furthermore, the ΔompR mutant displayed up to 2-log reduction in bacterial cell numbers in murine bladders and kidneys compared with wild-type bacteria after 5 days of infection. The ability of the bacteria to survive was restored to wild-type levels when the ΔompR mutant strain was complemented with wild-type ompR, but not when the alanine-substituted ompR gene was used. This study has fulfilled molecular Koch's postulates by showing the pivotal role OmpR plays in UPEC survival within the murine urinary tract.

scholarly journals Role of Motility in the Colonization of Uropathogenic Escherichia coli in the Urinary Tract

2005 ◽  
Vol 73 (11) ◽  
pp. 7644-7656 ◽  
Author(s):  
M. Chelsea Lane ◽  
Virginia Lockatell ◽  
Greta Monterosso ◽  
Daniel Lamphier ◽  
Julia Weinert ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Wild Type Strain ◽  
Uropathogenic Escherichia Coli ◽  
Wild Type ◽  
Upec Strain ◽  
Host Immune Responses ◽  
Strain Cft073 ◽  
Tract Infections

ABSTRACT Uropathogenic Escherichia coli (UPEC) causes most uncomplicated urinary tract infections (UTIs) in humans. Flagellum-mediated motility and chemotaxis have been suggested to contribute to virulence by enabling UPEC to escape host immune responses and disperse to new sites within the urinary tract. To evaluate their contribution to virulence, six separate flagellar mutations were constructed in UPEC strain CFT073. The mutants constructed were shown to have four different flagellar phenotypes: fliA and fliC mutants do not produce flagella; the flgM mutant has similar levels of extracellular flagellin as the wild type but exhibits less motility than the wild type; the motAB mutant is nonmotile; and the cheW and cheY mutants are motile but nonchemotactic. Virulence was assessed by transurethral independent challenges and cochallenges of CBA mice with the wild type and each mutant. CFU/ml of urine or CFU/g bladder or kidney was determined 3 days postinoculation for the independent challenges and at 6, 16, 48, 60, and 72 h postinoculation for the cochallenges. While these mutants colonized the urinary tract during independent challenge, each of the mutants was outcompeted by the wild-type strain to various degrees at specific time points during cochallenge. Altogether, these results suggest that flagella and flagellum-mediated motility/chemotaxis may not be absolutely required for virulence but that these traits contribute to the fitness of UPEC and therefore significantly enhance the pathogenesis of UTIs caused by UPEC.

scholarly journals Role of rpoS in Acid Resistance and Fecal Shedding of Escherichia coli O157:H7

2000 ◽  
Vol 66 (2) ◽  
pp. 632-637 ◽  
Author(s):  
Stuart B. Price ◽  
Chorng-Ming Cheng ◽  
Charles W. Kaspar ◽  
James C. Wright ◽  
Fred J. DeGraves ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Acid Resistance ◽  
Wild Type ◽  
Fecal Shedding ◽  
E Coli ◽  
Cattle Herds

ABSTRACT Acid resistance (AR) is important to survival of Escherichia coli O157:H7 in acidic foods and may play a role during passage through the bovine host. In this study, we examined the role in AR of the rpoS-encoded global stress response regulator ςS and its effect on shedding of E. coliO157:H7 in mice and calves. When assayed for each of the three AR systems identified in E. coli, an rpoS mutant (rpoS::pRR10) of E. coli O157:H7 lacked the glucose-repressed system and possessed reduced levels of both the arginine- and glutamate-dependent AR systems. After administration of the rpoS mutant and the wild-type strain (ATCC 43895) to ICR mice at doses ranging from 101 to 104 CFU, we found the wild-type strain in feces of mice given lower doses (102 versus 103 CFU) and at a greater frequency (80% versus 13%) than the mutant strain. The reduction in passage of the rpoS mutant was due to decreased AR, as administration of the mutant in 0.05 M phosphate buffer facilitated passage and increased the frequency of recovery in feces from 27 to 67% at a dose of 104 CFU. Enumeration ofE. coli O157:H7 in feces from calves inoculated with an equal mixture of the wild-type strain and the rpoS mutant demonstrated shedding of the mutant to be 10- to 100-fold lower than wild-type numbers. This difference in shedding between the wild-type strain and the rpoS mutant was statistically significant (P ≤ 0.05). Thus, ςS appears to play a role in E. coli O157:H7 passage in mice and shedding from calves, possibly by inducing expression of the glucose-repressed RpoS-dependent AR determinant and thus increasing resistance to gastrointestinal stress. These findings may provide clues for future efforts aimed at reducing or eliminating this pathogen from cattle herds.

scholarly journals Mutations in Four Regulatory Genes Have Interrelated Effects on Heterocyst Maturation in Anabaena sp. Strain PCC 7120

2006 ◽  
Vol 188 (21) ◽  
pp. 7387-7395 ◽  
Author(s):  
Sigal Lechno-Yossef ◽  
Qing Fan ◽  
Shigeki Ehira ◽  
Naoki Sato ◽  
C. Peter Wolk
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Regulatory System ◽  
Transcript Abundance ◽  
Regulatory Genes ◽  
Wild Type ◽  
Serine Threonine Kinase ◽  
In The Wild ◽  
Pcc 7120

ABSTRACT Regulatory genes hepK, hepN, henR, and hepS are required for heterocyst maturation in Anabaena sp. strain PCC 7120. They presumptively encode two histidine kinases, a response regulator, and a serine/threonine kinase, respectively. To identify relationships between those genes, we compared global patterns of gene expression, at 14 h after nitrogen step-down, in corresponding mutants and in the wild-type strain. Heterocyst envelopes of mutants affected in any of those genes lack a homogeneous, polysaccharide layer. Those of a henR mutant also lack a glycolipid layer. patA, which encodes a positive effector of heterocyst differentiation, was up-regulated in all mutants except the hepK mutant, suggesting that patA expression may be inhibited by products related to heterocyst development. hepS and hepK were up-regulated if mutated and so appear to be negatively autoregulated. HepS and HenR regulated a common set of genes and so appear to belong to one regulatory system. Some nontranscriptional mechanism may account for the observation that henR mutants lack, and hepS mutants possess, a glycolipid layer, even though both mutations down-regulated genes involved in formation of the glycolipid layer. HepK and HepN also affected transcription of a common set of genes and therefore appear to share a regulatory pathway. However, the transcript abundance of other genes differed very significantly from expression in the wild-type strain in either the hepK or hepN mutant while differing very little from wild-type expression in the other of those two mutants. Therefore, hepK and hepN appear to participate also in separate pathways.

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 PhoU enhances the ability of extraintestinal pathogenic Escherichia coli strain CFT073 to colonize the murine urinary tract

Microbiology ◽  
2006 ◽  
Vol 152 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Eric L. Buckles ◽  
Xiaolin Wang ◽  
C. Virginia Lockatell ◽  
David E. Johnson ◽  
Michael S. Donnenberg
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Mutant Strain ◽  
Human Urine ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Strain Cft073

The phoU gene is the last cistron in the pstSCAB–phoU operon and functions as a negative regulator of the Pho regulon. The authors previously identified a phoU mutant of extraintestinal pathogenic Escherichia coli strain CFT073 and demonstrated that this mutant was attenuated for survival in the murine model of ascending urinary tract infection. It is hypothesized that the PhoU protein might serve as a urovirulence factor by indirectly affecting the expression of virulence-related genes. In this study, the phoU mutant was further characterized and PhoU was confirmed as a virulence factor. Western blot analysis demonstrated that insertion of the transposon in the phoU gene disrupted the expression of PhoU. The phoU mutant had derepressed alkaline phosphatase activity under phosphate-excess and -limiting conditions. In single-challenge murine ascending urinary tract infection experiments, quantitative cultures of urine, bladder and kidney revealed no significant differences between the phoU mutant strain and the wild-type strain CFT073. However, in competitive colonization experiments, the phoU mutant strain was significantly out-competed by the wild-type strain in the kidneys and urine and recovered in lower amount in the bladder. Complementation of the phoU mutant with a plasmid containing the wild-type phoU gene restored the expression of PhoU and alkaline phosphate activity to wild-type levels and no significant difference in colonization was observed between the phoU mutant containing the complementing plasmid and wild-type in competitive colonization experiments. In human urine, the phoU mutant and wild-type grew comparably when inoculated independently, indicating that the attenuation observed was not due to a general growth defect. However, as observed in vivo, the wild-type out-competed the phoU mutant in competition growth experiments in human urine. These data indicate that PhoU contributes to efficient colonization of the murine urinary tract and add PhoU to a short list of confirmed urovirulence factors.

scholarly journals Loss of Regulatory Protein RfaH Attenuates Virulence of Uropathogenic Escherichia coli

2002 ◽  
Vol 70 (8) ◽  
pp. 4406-4413 ◽  
Author(s):  
Gábor Nagy ◽  
Ulrich Dobrindt ◽  
György Schneider ◽  
A. Salam Khan ◽  
Jörg Hacker ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Mouse Model ◽  
Type Strain ◽  
Wild Type Strain ◽  
Regulatory Protein ◽  
Wild Type ◽  
Serovar Typhimurium

ABSTRACT RfaH is a regulatory protein in Escherichia coli and Salmonella enterica serovar Typhimurium. Although it enhances expression of different factors that are proposed to play a role in bacterial virulence, a direct effect of RfaH on virulence has not been investigated so far. We report that inactivation of rfaH dramatically decreases the virulence of uropathogenic E. coli strain 536 in an ascending mouse model of urinary tract infection. The mortality rate caused by the wild-type strain in this assay is 100%, whereas that of its isogenic rfaH mutant does not exceed 18%. In the case of coinfection, the wild-type strain 536 shows higher potential to colonize the urinary tract even when it is outnumbered 100-fold by its rfaH mutant in the inoculum. In contrast to the wild-type strain, serum resistance of strain 536rfaH::cat is fully abolished. Furthermore, we give evidence that, besides a major decrease in the amount of hemin receptor ChuA (G. Nagy, U. Dobrindt, M. Kupfer, L. Emody, H. Karch, and J. Hacker, Infect. Immun. 69:1924-1928, 2001), loss of the RfaH protein results in an altered lipopolysaccharide phenotype as well as decreased expression of K15 capsule and alpha-hemolysin, whereas levels of other pathogenicity factors such as siderophores, flagella, Prf, and S fimbriae appear to be unaltered in strain 536rfaH::cat in comparison to the wild-type strain. trans complementation of the mutant strain with the rfaH gene restores wild-type levels of the affected virulence factors and consequently restitutes virulence in the mouse model of ascending urinary tract infection.

scholarly journals Inactivation of ibeA and ibeT Results in Decreased Expression of Type 1 Fimbriae in Extraintestinal Pathogenic Escherichia coli Strain BEN2908

2008 ◽  
Vol 76 (9) ◽  
pp. 4129-4136 ◽  
Author(s):  
Mélanie A. M. Cortes ◽  
Julien Gibon ◽  
Nathalie K. Chanteloup ◽  
Maryvonne Moulin-Schouleur ◽  
Philippe Gilot ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Wild Type Strain ◽  
Coli Strain ◽  
Wild Type ◽  
Adhesive Properties ◽  
Type 1 Fimbriae ◽  
Pathogenic Escherichia Coli ◽  
Genes Encoding

ABSTRACT IbeA in extraintestinal pathogenic Escherichia coli (ExPEC) strains was previously described for its role in invasion. Here we investigated the role of IbeA and IbeT, encoded by a gene located downstream of ibeA, in the adhesion of the avian ExPEC strain BEN2908 to human brain microvascular endothelial cells (HBMEC). The ΔibeA mutant was less adhesive to HBMEC than the wild-type strain BEN2908 was. Because strain BEN2908 also expresses type 1 fimbriae, we measured the adhesion specifically due to IbeA by comparing the adhesive properties of a Δfim derivative of strain BEN2908 to those of a double Δfim ΔibeA mutant. No differences were observed, indicating that the reduction of adhesion in BEN2908 ΔibeA could be due to a decrease in type 1 fimbria expression. We indeed showed that the decreased adhesion of BEN2908 ΔibeA was correlated with a decrease in type 1 fimbria expression. Accordingly, more bacteria had a fim promoter orientated in the off position in a culture of BEN2908 ΔibeA than in a culture of BEN2908. Expression of fimB and fimE, two genes encoding recombinases participating in controlling the orientation of the fim promoter, was decreased in BEN2908 ΔibeA. A reduction of type 1 fimbria expression due to a preferential orientation of the fim promoter in the off position was also seen in an ibeT mutant of strain BEN2908. We finally suggest a role for IbeA and IbeT in modulating the expression of type 1 fimbriae through an as yet unknown mechanism.

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 RpoS Proteolysis Is Regulated by a Mechanism That Does Not Require the SprE (RssB) Response Regulator Phosphorylation Site

2004 ◽  
Vol 186 (21) ◽  
pp. 7403-7410 ◽  
Author(s):  
Celeste N. Peterson ◽  
Natividad Ruiz ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Sigma Factor ◽  
Response Regulator ◽  
Phosphorylation Site ◽  
Carbon Starvation ◽  
Logarithmic Phase ◽  
Acetyl Phosphate ◽  
Wild Type ◽  
Basal Activity ◽  
Sigma Factor Rpos

ABSTRACT In Escherichia coli the response regulator SprE (RssB) facilitates degradation of the sigma factor RpoS by delivering it to the ClpXP protease. This process is regulated: RpoS is degraded in logarithmic phase but becomes stable upon carbon starvation, resulting in its accumulation. Because SprE contains a CheY domain with a conserved phosphorylation site (D58), the prevailing model posits that this control is mediated by phosphorylation. To test this model, we mutated the conserved response regulator phosphorylation site (D58A) of the chromosomal allele of sprE and monitored RpoS levels in response to carbon starvation. Though phosphorylation contributed to the SprE basal activity, we found that RpoS proteolysis was still regulated upon carbon starvation. Furthermore, our results indicate that phosphorylation of wild-type SprE occurs by a mechanism that is independent of acetyl phosphate.

scholarly journals Adhesion of Escherichia Coli to Nanostructured Surfaces and the Role of Type 1 Fimbriae

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2247
Author(s):  
Pawel Kallas ◽  
Håvard J Haugen ◽  
Nikolaj Gadegaard ◽  
John Stormonth-Darling ◽  
Mats Hulander ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Urinary Tract Infections ◽  
Virulence Factor ◽  
Wild Type ◽  
E Coli ◽  
Type 1 Fimbriae ◽  
Tract Infections

Bacterial fimbriae are an important virulence factor mediating adhesion to both biotic and abiotic surfaces and facilitating biofilm formation. The expression of type 1 fimbriae of Escherichia coli is a key virulence factor for urinary tract infections and catheter-associated urinary tract infections, which represent the most common nosocomial infections. New strategies to reduce adhesion of bacteria to surfaces is therefore warranted. The aim of the present study was to investigate how surfaces with different nanotopography-influenced fimbriae-mediated adhesion. Surfaces with three different nanopattern surface coverages made in polycarbonate were fabricated by injection molding from electron beam lithography nanopatterned templates. The surfaces were constructed with features of approximately 40 nm width and 25 nm height with 100 nm, 250 nm, and 500 nm interspace distance, respectively. The role of fimbriae type 1-mediated adhesion was investigated using the E. coli wild type BW25113 and ΔfimA (with a knockout of major pilus protein FimA) and ΔfimH (with a knockout of minor protein FimH) mutants. For the surfaces with nanotopography, all strains adhered least to areas with the largest interpillar distance (500 nm). For the E. coli wild type, no difference in adhesion between surfaces without pillars and the largest interpillar distance was observed. For the deletion mutants, increased adhesion was observed for surfaces without pillars compared to surfaces with the largest interpillar distance. The presence of a fully functional type 1 fimbria decreased the bacterial adhesion to the nanopatterned surfaces in comparison to the mutants.

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