Human Urine Decreases Function and Expression of Type 1 Pili in Uropathogenic Escherichia coli

Greene, Sarah E.; Hibbing, Michael E.; Janetka, James W.; Chen, Swaine L.; Hultgren, Scott J.

doi:10.1128/mbio.00820-15

Cited by 69 publications

(69 citation statements)

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“…The opposing activities of FimB and FimE, as well as stochastic engagement of each recombinase with the fim promoter, lead to mixed populations of bacteria that carry the fim promoter element in the fim ON or fim OFF state within the same culture (27). In addition to controlling the orientation of promoter DNA, transcription of the fim operon is subject to control by other DNA binding proteins that either affect fim transcription directly or interfere with Fim recombinase activity on the fim promoter (26,29,30,32,(38)(39)(40)(41)(42)(43).…”

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confidence: 99%

The UbiI (VisC) Aerobic Ubiquinone Synthase Is Required for Expression of Type 1 Pili, Biofilm Formation, and Pathogenesis in Uropathogenic Escherichia coli

et al. 2016

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Uropathogenic Escherichia coli (UPEC), which causes the majority of urinary tract infections (UTI), uses pilus-mediated adherence to initiate biofilm formation in the urinary tract. Oxygen gradients within E. coli biofilms regulate expression and localization of adhesive type 1 pili. A transposon mutant screen for strains defective in biofilm formation identified the ubiI (formerly visC) aerobic ubiquinone synthase gene as critical for UPEC biofilm formation. In this study, we characterized a nonpolar ubiI deletion mutant and compared its behavior to that of wild-type bacteria grown under aerobic and anoxic conditions. Consistent with its function as an aerobic ubiquinone-8 synthase, deletion of ubiI in UPEC resulted in reduced membrane potential, diminished motility, and reduced expression of chaperone-usher pathway pili. Loss of aerobic respiration was previously shown to negatively impact expression of type 1 pili. To determine whether this reduction in type 1 pili was due to an energy deficit, wildtype UPEC and the ubiI mutant were compared for energy-dependent phenotypes under anoxic conditions, in which quinone synthesis is undertaken by anaerobic quinone synthases. Under anoxic conditions, the two strains exhibited wild-type levels of motility but produced diminished numbers of type 1 pili, suggesting that the reduction of type 1 pilus expression in the absence of oxygen is not due to a cellular energy deficit. Acute-and chronic-infection studies in a mouse model of UTI revealed a significant virulence deficit in the ubiI mutant, indicating that UPEC encounters enough oxygen in the bladder to induce aerobic ubiquinone synthesis during infection. IMPORTANCEThe majority of urinary tract infections are caused by uropathogenic E. coli, a bacterium that can respire in the presence and absence of oxygen. The bladder environment is hypoxic, with oxygen concentrations ranging from 4% to 7%, compared to 21% atmospheric oxygen. This work provides evidence that aerobic ubiquinone synthesis must be engaged during bladder infection, indicating that UPEC bacteria sense and use oxygen as a terminal electron acceptor in the bladder and that this ability drives infection potential despite the fact that UPEC is a facultative anaerobe.T he distinct characteristics of biofilms make them a particularly significant concern in the clinical setting. The presence of extracellular matrix retards the penetration of antibiotics and provides protection from innate immune responses, including opsonization and phagocytosis (1, 2). In addition, the presence of environmental gradients within the biomass leads to community "division of labor," with subpopulations of bacteria exhibiting differential gene expression in response to local nutrient and oxygen availability and with some cells being essentially metabolically dormant (3-5).Recent studies in uropathogenic Escherichia coli (UPEC) biofilms have revealed the stratification of at least two types of adhesive fibers and possibly other factors in response to oxygen gradients (4)....

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confidence: 99%

The UbiI (VisC) Aerobic Ubiquinone Synthase Is Required for Expression of Type 1 Pili, Biofilm Formation, and Pathogenesis in Uropathogenic Escherichia coli

et al. 2016

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“…This mutation abrogates mannose binding by FimH but does not affect T1P assembly, leading to fimS being mostly phase OFF when grown in phase ON-inducing conditions. The mechanism for the higher phase OFF percentage is unknown, although chemical inhibition of FimH has the same effect (10). The percentage of phase OFF cells in the Q133K mutant was similar to that in the UIR mutants (Fig.…”

Section: Uir Mutants Regulate Phase Variation Through a Previously Unmentioning

confidence: 71%

“…The sensing of T1P misassembly is not as well characterized as that for P pili, although it does not seem to proceed through the Cpx system (45). Interestingly, bacteria can detect nonfunctional T1P subunits; disrupting the FimH mannosebinding pocket by mutation (Q133K) or small molecule inhibition turns fimS phase OFF (10). In UIR mutants, the loss of appropriate pilus subunit stoichiometry (possibly affecting pilus assembly) also leads to negative feedback regulation at fimS and up-regulation of S pili independent of the fim recombinases.…”

Section: Discussionmentioning

confidence: 99%

“…The FimH-Q133K mutant affects phase variation partially through FimE (10). To determine whether the fim recombinases also played a role in the UIR mutant phenotypes, we made the G398A mutation in a strain lacking all fim recombinases (fimB, fimE, and fimX) in UTI89.…”

Section: Uir Mutants Regulate Phase Variation Through a Previously Unmentioning

confidence: 99%

“…The interplay among these events determines the outcome of infection (8), ranging from full clearance to chronic active cystitis. T1P are important for most of these UTI stages and demonstrate dynamic regulation of expression that can be seen directly in human infections and urine (9,10).…”

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Comprehensive mutagenesis of thefimSpromoter regulatory switch reveals novel regulation of type 1 pili in uropathogenicEscherichia coli

Zhang

Susanto

Wan

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Type 1 pili (T1P) are major virulence factors for uropathogenic Escherichia coli (UPEC), which cause both acute and recurrent urinary tract infections. T1P expression therefore is of direct relevance for disease. T1P are phase variable (both piliated and nonpiliated bacteria exist in a clonal population) and are controlled by an invertible DNA switch (fimS), which contains the promoter for the fim operon encoding T1P. Inversion of fimS is stochastic but may be biased by environmental conditions and other signals that ultimately converge at fimS itself. Previous studies of fimS sequences important for T1P phase variation have focused on laboratory-adapted E. coli strains and have been limited in the number of mutations or by alteration of the fimS genomic context. We surmounted these limitations by using saturating genomic mutagenesis of fimS coupled with accurate sequencing to detect both mutations and phase status simultaneously. In addition to the sequences known to be important for biasing fimS inversion, our method also identifies a previously unknown pair of 5′ UTR inverted repeats that act by altering the relative fimA levels to control phase variation. Thus we have uncovered an additional layer of T1P regulation potentially impacting virulence and the coordinate expression of multiple pilus systems.urinary tract infection | fimS | type 1 pili | phase variation | saturating chromosomal mutagenesis U rinary tract infections (UTIs) are common infections that mostly affect women with an annual cost of billions of dollars (1). They are caused mainly by uropathogenic Escherichia coli (UPEC), which rely on several virulence factors to cause disease (2); type 1 pili (T1P) are perhaps the most important of these (3). T1P present a tip adhesin, FimH, that binds specifically to mannose, which is found on several glycosylated surface proteins, such as uroplakins and α1-and β3-integrins (4, 5), in the mammalian bladder. Binding to mannosylated proteins initiates a cascade of events including UPEC invasion of host tissues (2), formation of intracellular structures (6), and activation of the host immune response (7). The interplay among these events determines the outcome of infection (8), ranging from full clearance to chronic active cystitis. T1P are important for most of these UTI stages and demonstrate dynamic regulation of expression that can be seen directly in human infections and urine (9, 10).Thus, understanding T1P regulation is fundamental to understanding UTI. T1P have been well studied (11), mostly in laboratory-adapted E. coli strains. T1P are encoded by the fim operon; their expression is phase variable via inversion of fimS, a chromosomal DNA segment containing the fim promoter (12). This binary epigenetic switch results in bacteria switching between fimbriated and nonfimbriated states. Inversion is mediated by the FimB and FimE recombinases, whose genes are located immediately upstream of fimS (13) and are found in most E. coli strains (14). Inversion is influenced by numerous signals, such as temperatu...

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Urine: Waste product or biologically active tissue?

2018

Neurourology and Urodynamics

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Human Urine Decreases Function and Expression of Type 1 Pili in Uropathogenic Escherichia coli

Cited by 69 publications

References 39 publications

The UbiI (VisC) Aerobic Ubiquinone Synthase Is Required for Expression of Type 1 Pili, Biofilm Formation, and Pathogenesis in Uropathogenic Escherichia coli

The UbiI (VisC) Aerobic Ubiquinone Synthase Is Required for Expression of Type 1 Pili, Biofilm Formation, and Pathogenesis in Uropathogenic Escherichia coli

Comprehensive mutagenesis of thefimSpromoter regulatory switch reveals novel regulation of type 1 pili in uropathogenicEscherichia coli

Urine: Waste product or biologically active tissue?

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