The Escherichia coli BarA-UvrY two-component system is a virulence determinant in the urinary tract

Abstract

BackgroundThe Salmonella enterica BarA-SirA, the Erwinia carotovora ExpS-ExpA, the Vibrio cholerae BarA-VarA and the Pseudomonas spp GacS-GacA all belong to the same orthologous family of two-component systems as the Escherichia coli BarA-UvrY. In the first four species it has been demonstrated that disruption of this two-component system leads to a clear reduction in virulence of the bacteria. Our aim was to determine if the Escherichia coli BarA-UvrY two-component system is connected with virulence using a monkey cystitis model.ResultsCystitis was generated in Macaque fascularis monkeys by infecting the bladder with a 1:1 mixture of the uropathogenic Escherichia coli isolate DS17 and a derivative where the uvrY gene had been disrupted with a kanamycin resistance gene. Urine was collected through bladder punctuation at subsequent time intervals and the relative amount of uvrY mutant was determined. This showed that inactivation of the UvrY response regulator leads to a reduced fitness. In similar competitions in culture flasks with Luria Broth (LB) the uvrY mutant rather had a higher fitness than the wild type. When the competitions were done in flasks with human urine the uvrY mutant initially had a lower fitness. This was followed by a fluctuation in the level of mutant in the long-term culture, with a pattern that was specific for the individual urines that were tested. Addition of LB to the different urine competition cultures however clearly led to a consistently higher fitness of the uvrY mutant.ConclusionThis paper demonstrates that the BarA-UvrY two-component system is a determinant for virulence in a monkey cystitis model. The observed competition profiles strengthen our previous hypothesis that disruption of the BarA-UvrY two-component system impairs the ability of the bacteria to switch between different carbon sources. The urine in the bladder contains several different carbon sources and its composition changes over time. Inability to efficiently switch between the carbon sources may thus provide an explanation to the reduced fitness of the uvrY mutant in the cystitis model.

BarA-UvrY Two-Component System Regulates Virulence of Uropathogenic E. coli CFT073

“…It is also reported that pyelonephritogenic E. coli strains are more cytotoxic to cultured human renal tubular epithelial cells and the cytotoxin hemolysin contributes to this potent virulence as well [44]. A previous study showed that disruption of the BarA-UvrY TCS reduced the fitness of the uvrY mutant in a monkey cystitis model [40]. Similarly, in our assay, mutation in uvrY reduces the cytotoxicity to the cultured human kidney (HK-2 cells) and hemolysin production (Figure 3 & 4, Table 4 & 5).…”

Protein solubility and differential proteomic profiling of recombinant Escherichia coli overexpressing double-tagged fusion proteins

“…As a gluconeogenic medium, amino acids and other small metabolites in LB fuel directly into the Krebs (TCA) cycle [24]. After IPTG induction, more gluconeogenesis takes place in order to generate glucose phosphate for the pentose phosphate pathway.…”

Metabolic Adaptations of Uropathogenic E. coli in the Urinary Tract

“…Loss of the response regulator UvrY results in decreased fitness in both monkey cystitis and murine ascending UTI competition models (Tomenius et al, 2006; Palaniyandi et al, 2012), and decreased invasion of uroepithelial cells (Palaniyandi et al, 2012). Thus, the ability to effectively sense and utilize the mixture of gluconeogenic and glycolytic carbon sources within urine is a key metabolic adaption for UPEC survival.…”