scholarly journals Multiple Genes Repress Motility in Uropathogenic Escherichia coli Constitutively Expressing Type 1 Fimbriae

2008 ◽  
Vol 190 (10) ◽  
pp. 3747-3756 ◽  
Author(s):  
Amy N. Simms ◽  
Harry L. T. Mobley
Keyword(s):  
Escherichia Coli ◽  
Mismatch Repair ◽  
Constitutive Expression ◽  
Mismatch Repair Gene ◽  
Repair Gene ◽  
Upec Strain ◽  
Type 1 Fimbriae ◽  
Multiple Genes ◽  
Strain Cft073

ABSTRACT Two surface organelles of uropathogenic Escherichia coli (UPEC), flagella and type 1 fimbriae, are critical for colonization of the urinary tract but mediate opposite actions. Flagella propel bacteria through urine and along mucus layers, while type 1 fimbriae allow bacteria to adhere to specific receptors present on uroepithelial cells. Constitutive expression of type 1 fimbriae leads to repression of motility and chemotaxis in UPEC strain CFT073, suggesting that UPEC may coordinately regulate motility and adherence. To identify genes involved in this regulation of motility by type 1 fimbriae, transposon mutagenesis was performed on a phase-locked type 1 fimbrial ON variant of strain CFT073 (CFT073 fim L-ON), followed by a screen for restoration of motility in soft agar. Functions of the genes identified included attachment, metabolism, transport, DNA mismatch repair, and transcriptional regulation, and a number of genes had hypothetical function. Isogenic deletion mutants of these genes were also constructed in CFT073 fim L-ON. Motility was partially restored in six of these mutants, including complementable mutations in four genes encoding known transcriptional regulators, lrhA, lrp, slyA, and papX; a mismatch repair gene, mutS; and one hypothetical gene, ydiV. Type 1 fimbrial expression in these mutants was unaltered, and the majority of these mutants expressed larger amounts of flagellin than the fim L-ON parental strain. Our results indicate that repression of motility in CFT073 fim L-ON is not solely due to the constitutive expression of type 1 fimbriae on the surfaces of the bacteria and that multiple genes may contribute to this repression.

scholarly journals Complex Interplay between Type 1 Fimbrial Expression and Flagellum-Mediated Motility of Uropathogenic Escherichia coli

2007 ◽  
Vol 189 (15) ◽  
pp. 5523-5533 ◽  
Author(s):  
M. Chelsea Lane ◽  
Amy N. Simms ◽  
Harry L. T. Mobley
Keyword(s):  
Escherichia Coli ◽  
Constitutive Expression ◽  
Complex Interplay ◽  
Phenotypic Effect ◽  
Upec Strain ◽  
Partial Restoration ◽  
Type 1 Fimbriae ◽  
K 12 ◽  
The Relationship

ABSTRACT Type 1 fimbriae and flagella have been previously shown to contribute to the virulence of uropathogenic Escherichia coli (UPEC) within the urinary tract. In this study, the relationship between motility and type 1 fimbrial expression was tested for UPEC strain CFT073 by examining the phenotypic effect of fimbrial expression on motility and the effect that induction of motility has on type 1 fimbrial expression. While constitutive expression of type 1 fimbriae resulted in a significant decrease in motility and flagellin expression (P < 0.0001), a loss of type 1 fimbrial expression did not result in increased motility. Additionally, hypermotility and flagellar gene over- and underexpression were not observed to affect the expression of type 1 fimbriae. Hence, it appeared that the relationship between type 1 fimbrial expression and motility is unidirectional, where the overexpression of type 1 fimbriae dramatically affects motility and flagellum expression but not vice versa. Moreover, the constitutive expression of type 1 fimbriae in UPEC cystitis isolate F11 and the laboratory strain E. coli K-12 MG1655 also resulted in decreased motility, suggesting that this phenomenon is not specific to CFT073 or UPEC in general. Lastly, by analyzing the repression of motility caused by constitutive type 1 fimbrial expression, it was concluded that the synthesis and presence of type 1 fimbriae at the bacterial surface is only partially responsible for the repression of motility, as evidenced by the partial restoration of motility in the CFT073 fim L-ON ΔfimAICDFGH mutant. Altogether, these data provide further insight into the complex interplay between type 1 fimbrial expression and flagellum-mediated motility.

scholarly journals Decreased Expression of Type 1 Fimbriae by apstMutant of Uropathogenic Escherichia coli Reduces Urinary Tract Infection

2012 ◽  
Vol 80 (8) ◽  
pp. 2802-2815 ◽  
Author(s):  
Sébastien Crépin ◽  
Sébastien Houle ◽  
Marie-Ève Charbonneau ◽  
Michaël Mourez ◽  
Josée Harel ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Bacterial Virulence ◽  
Pho Regulon ◽  
Upec Strain ◽  
Content Type ◽  
Type 1 Fimbriae ◽  
Genes Encoding ◽  
Tract Infections

ABSTRACTThepstSCAB-phoUoperon encodes the phosphate-specific transport system (Pst). Loss of Pst constitutively activates the Pho regulon and decreases bacterial virulence. However, specific mechanisms underlying decreased bacterial virulence through inactivation of Pst are poorly understood. In uropathogenicEscherichia coli(UPEC) strain CFT073, inactivation ofpstdecreased urinary tract colonization in CBA/J mice. Thepstmutant was deficient in production of type 1 fimbriae and showed decreased expression of thefimAstructural gene which correlated with differential expression of thefimB,fimE,ipuA, andipbAgenes, encoding recombinases, mediating inversion of thefimpromoter. The role offimdownregulation in attenuation of thepstmutant was confirmed using afimphase-locked-on derivative, which demonstrated a significant gain in virulence. In addition, thepstmutant was less able to invade human bladder epithelial cells. Since type 1 fimbriae contribute to UPEC virulence by promoting colonization and invasion of bladder cells, the reduced bladder colonization by thepstmutant is predominantly attributed to downregulation of these fimbriae. Elucidation of mechanisms mediating the control of type 1 fimbriae through activation of the Pho regulon in UPEC may open new avenues for therapeutics or prophylactics against urinary tract infections.

scholarly journals Escherichia coli type-1 fimbriae are critical to overcome initial bottlenecks of infection upon low-dose inoculation in a porcine model of cystitis

Microbiology ◽  
2021 ◽  
Vol 167 (10) ◽  
Author(s):  
Kristian Stærk ◽  
Rasmus Birkholm Grønnemose ◽  
Thomas Kastberg Nielsen ◽  
Nicky Anúel Petersen ◽  
Yaseelan Palarasah ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Porcine Model ◽  
Post Inoculation ◽  
Upec Strain ◽  
Content Type ◽  
Type 1 Fimbriae ◽  
Susceptibility To Infection ◽  
General Importance

Most uropathogenic Escherichia coli (UPEC) express type-1 fimbriae (T1F), a key virulence factor for urinary tract infection (UTI) in mice. Evidence that conclusively associates this pilus with uropathogenesis in humans has, however, been difficult to obtain. We used an experimental porcine model of cystitis to assess the role of T1F in larger mammals more closely related to humans. Thirty-one pigs were infected with UPEC strain UTI89 or its T1F deficient mutant, UTI89ΔfimH, at inoculum titres of 102 to 108 colony forming units per millilitre. Urine and blood samples were collected and analysed 7 and 14 days post-inoculation, and whole bladders were removed at day 14 and analysed for uroepithelium-associated UPEC. All animals were consistently infected and reached high urine titres independent of inoculum titre. UTI89ΔfimH successfully colonized the bladders of 1/6 pigs compared to 6/6 for the wild-type strain. Intracellular UPEC were detectable in low numbers in whole bladder explants. In conclusion, low doses of UPEC are able to establish robust infections in pigs, similar to what is presumed in humans. T1F are critical for UPEC to surpass initial bottlenecks during infection but may be dispensable once infection is established. While supporting the conclusions from mice studies regarding a general importance of T1F in successfully infecting the host, the porcine UTI models’ natural high, more human-like, susceptibility to infection, allowed us to demonstrate a pivotal role of T1F in initial establishment of infection upon a realistic low-inoculum introduction of UPEC in the bladder.

scholarly journals Activation of NLRP3 by uropathogenic Escherichia coli is associated with IL-1β release and regulation of antimicrobial properties in human neutrophils

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Isak Demirel ◽  
Alexander Persson ◽  
Annelie Brauner ◽  
Eva Särndahl ◽  
Robert Kruse ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nlrp3 Inflammasome ◽  
Serine Proteases ◽  
Antimicrobial Properties ◽  
Human Neutrophils ◽  
Dependent Manner ◽  
Upec Strain ◽  
Caspase 1 ◽  
Strain Cft073

AbstractThe NLRP3 inflammasome and IL-1β have recently been linked to the severity of uropathogenic Escherichia coli (UPEC)-mediated urinary tract infection (UTI). However, not much is known about the contribution of NLRP3 to the antimicrobial properties of neutrophils and the release of IL-1β during UPEC infection. The purpose of this study was to elucidate the mechanisms behind UPEC-induced IL-1β release from human neutrophils, and to investigate the contribution of the NLRP3 inflammasome in neutrophil-mediated inhibition of UPEC growth. We found that the UPEC strain CFT073 increased the expression of NLRP3 and increased caspase-1 activation and IL-1β release from human neutrophils. The IL-1β release was mediated by the NLRP3 inflammasome and by serine proteases in an NF-κB-and cathepsin B-dependent manner. The UPEC virulence factors α-hemolysin, type-1 fimbriae and p-fimbriae were all shown to contribute to UPEC mediated IL-1β release from neutrophils. Furthermore, inhibition of caspase-1 and NLRP3 activation increased neutrophil ROS-production, phagocytosis and the ability of neutrophils to suppress UPEC growth. In conclusion, this study demonstrates that UPEC can induce NLRP3 and serine protease-dependent release of IL-1β from human neutrophils and that NLRP3 and caspase-1 can regulate the antimicrobial activity of human neutrophils against UPEC.

scholarly journals Spontaneously Arising mutL Mutators in Evolving Escherichia coli Populations Are the Result of Changes in Repeat Length

2003 ◽  
Vol 185 (20) ◽  
pp. 6076-6082 ◽  
Author(s):  
Aaron C. Shaver ◽  
Paul D. Sniegowski
Keyword(s):  
Escherichia Coli ◽  
Mismatch Repair ◽  
Mutation Rate ◽  
Mismatch Repair Gene ◽  
Dna Repeats ◽  
Wild Type ◽  
Repair Gene ◽  
Mutator Strains ◽  
Experimental Populations

ABSTRACT Over the course of thousands of generations of growth in a glucose-limited environment, 3 of 12 experimental populations of Escherichia coli spontaneously and independently evolved greatly increased mutation rates. In two of the populations, the mutations responsible for this increased mutation rate lie in the same region of the mismatch repair gene mutL. In this region, a 6-bp repeat is present in three copies in the gene of the wild-type ancestor of the experimental populations but is present in four copies in one of the experimental populations and two copies in the other. These in-frame mutations either add or delete the amino acid sequence LA in the MutL protein. We determined that the replacement of the wild-type sequence with either of these mutations was sufficient to increase the mutation rate of the wild-type strain to a level comparable to that of the mutator strains. Complementation of strains bearing the mutator mutations with wild-type copies of either mutL or the mismatch repair gene uvrD rescued the wild-type mutation rate. The position of the mutator mutations—in the region of MutL known as the ATP lid—suggests a possible deficiency in MutL's ATPase activity as the cause of the mutator phenotype. The similarity of the two mutator mutations (despite the independent evolutionary histories of the populations that gave rise to them) leads to a discussion of the potential adaptive role of DNA repeats.

scholarly journals Involvement of Mismatch Repair in the Reciprocal Control of Motility and Adherence of Uropathogenic Escherichia coli

2012 ◽  
Vol 80 (6) ◽  
pp. 1969-1979 ◽  
Author(s):  
Lauren A. Cooper ◽  
Lyle A. Simmons ◽  
Harry L. T. Mobley
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Mismatch Repair ◽  
Upper Urinary Tract ◽  
Wild Type ◽  
Content Type ◽  
Partial Restoration ◽  
Type 1 Fimbriae ◽  
Tract Infections

ABSTRACTType 1 fimbriae and flagella, two surface organelles critical for colonization of the urinary tract by uropathogenicEscherichia coli(UPEC), mediate opposing virulence objectives. Type 1 fimbriae facilitate adhesion to mucosal cells and promote bacterial persistence in the urinary tract, while flagella propel bacteria through urine and along mucous layers during ascension to the upper urinary tract. Using a transposon screen of theE. coliCFT073fimlocked-ON (L-ON) mutant, a construct that constitutively expresses type 1 fimbriae and represses motility, we identified six mutants that exhibited a partial restoration of motility. Among these six mutated genes wasmutS, which encodes a component of the methyl-directed mismatch repair (MMR) system. When complemented withmutS in trans, motility was again repressed. To determine whether the MMR system, in general, is involved in this reciprocal control, we characterized the effects of gene deletions of other MMR components on UPEC motility. Isogenic deletions ofmutS,mutH, andmutLwere constructed in both wild-type CFT073 andfimL-ON backgrounds. All MMR mutants showed an increase in motility in the wild-type background, and ΔmutHand ΔmutSmutations increased motility in thefimL-ON background. Cochallenge of the wild-type strain with an MMR-defective strain showed a subtle but significant competitive advantage in the bladder and spleen for the MMR mutant using the murine model of ascending urinary tract infection after 48 h. Our findings demonstrate that the MMR system generally affects the reciprocal regulation of motility and adherence and thus could contribute to UPEC pathogenesis during urinary tract infections.

Hypothesis: Possible role of retinoic acid therapy in patients with biallelic mismatch repair gene defects

2007 ◽  
Vol 167 (2) ◽  
pp. 225-229 ◽  
Author(s):  
Sven Gottschling ◽  
Harald Reinhard ◽  
Constanze Pagenstecher ◽  
Stefan Krüger ◽  
Jochen Raedle ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Mismatch Repair ◽  
Mismatch Repair Gene ◽  
Repair Gene ◽  
Acid Therapy ◽  
Gene Defects
Sign in / Sign up

Export Citation Format

Share Document