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OmpR regulation of the uropathogenic Escherichia coli fimB gene in an acidic/high osmolality environment.

ABSTRACT: Uropathogenic Escherichia coli (UPEC) causes more than 90?% of all human urinary tract infections through type 1 piliated UPEC cells binding to bladder epithelial cells. The FimB and FimE site-specific recombinases orient the fimS element containing the fimA structural gene promoter. Regulation of fimB and fimE depends on environmental pH and osmolality. The EnvZ/OmpR two-component system affects osmoregulation in E. coli. To ascertain if OmpR directly regulated the fimB gene promoters, gel mobility shift and DNase I footprinting experiments were performed using OmpR or phosphorylated OmpR (OmpR-P) mixed with the fimB promoter regions of UPEC strain NU149. Both OmpR-P and OmpR bound weakly to one fimB promoter. Because there was weak binding to one fimB promoter, strain NU149 was grown in different pH and osmolality environments, and total RNAs were extracted from each population and converted to cDNAs. Quantitative reverse-transcriptase PCR showed no differences in ompR transcription among the different growth conditions. Conversely, Western blots showed a significant increase in OmpR protein in UPEC cells grown in a combined low pH/high osmolality environment versus a neutral pH/high osmolality environment. In a high osmolality environment, the ompR mutant expressed more fimB transcripts and Phase-ON positioning of the fimS element as well as higher type 1 pili levels than wild-type cells. Together these results suggest that OmpR may be post-transcriptionally regulated in UPEC cells growing in a low pH/high osmolality environment, which regulates fimB in UPEC.

SUBMITTER: Rentschler AE

PROVIDER: S-EPMC3709560 | biostudies-literature | 2013 Feb

REPOSITORIES: biostudies-literature

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OmpR regulation of the uropathogenic Escherichia coli fimB gene in an acidic/high osmolality environment.

Rentschler Ann E AE Lovrich Steven D SD Fitton Robert R Enos-Berlage Jodi J Schwan William R WR

Microbiology (Reading, England) 20121122 Pt 2

Uropathogenic Escherichia coli (UPEC) causes more than 90 % of all human urinary tract infections through type 1 piliated UPEC cells binding to bladder epithelial cells. The FimB and FimE site-specific recombinases orient the fimS element containing the fimA structural gene promoter. Regulation of fimB and fimE depends on environmental pH and osmolality. The EnvZ/OmpR two-component system affects osmoregulation in E. coli. To ascertain if OmpR directly regulated the fimB gene promoters, gel mobi ...[more]

PMID: 23175504

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Project description:Urinary tract infection (UTI) is among the most common infections treated worldwide each year and is caused primarily by uropathogenic Escherichia coli (UPEC). Rising rates of antibiotic resistance among uropathogens have spurred a consideration of alternative treatment strategies, such as bacteriophage (phage) therapy; however, phage-bacterial interactions within the urinary environment are poorly defined. Here, we assess the activity of two phages, namely, HP3 and ES17, against clinical UPEC isolates using in vitro and in vivo models of UTI. In both bacteriologic medium and pooled human urine, we identified phage resistance arising within the first 6 to 8 h of coincubation. Whole-genome sequencing revealed that UPEC strains resistant to HP3 and ES17 harbored mutations in genes involved in lipopolysaccharide (LPS) biosynthesis. Phage-resistant strains displayed several in vitro phenotypes, including alterations to adherence to and invasion of human bladder epithelial HTB-9 cells and increased biofilm formation in some isolates. Interestingly, these phage-resistant UPEC isolates demonstrated reduced growth in pooled human urine, which could be partially rescued by nutrient supplementation and were more sensitive to several outer membrane-targeting antibiotics than parental strains. Additionally, phage-resistant UPEC isolates were attenuated in bladder colonization in a murine UTI model. In total, our findings suggest that while resistance to phages, such as HP3 and ES17, may arise readily in the urinary environment, phage resistance is accompanied by fitness costs which may render UPEC more susceptible to host immunity or antibiotics. IMPORTANCE UTI is one of the most common causes of outpatient antibiotic use, and rising antibiotic resistance threatens the ability to control UTI unless alternative treatments are developed. Bacteriophage (phage) therapy is gaining renewed interest; however, much like with antibiotics, bacteria can readily become resistant to phages. For successful UTI treatment, we must predict how bacteria will evade killing by phage and identify the downstream consequences of phage resistance during bacterial infection. In our current study, we found that while phage-resistant bacteria quickly emerged in vitro, these bacteria were less capable of growing in human urine and colonizing the murine bladder. These results suggest that phage therapy poses a viable UTI treatment if phage resistance confers fitness costs for the uropathogen. These results have implications for developing cocktails of phage with multiple different bacterial targets, of which each is evaded only at the cost of bacterial fitness.

Dataset Information

OmpR regulation of the uropathogenic Escherichia coli fimB gene in an acidic/high osmolality environment.

Publications

OmpR regulation of the uropathogenic Escherichia coli fimB gene in an acidic/high osmolality environment.

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