Project description:Proteus mirabilis is a leading cause of catheter-associated urinary tract infections (UTIs) and urolithiasis. The transcriptional regulator MrpJ inversely modulates two critical aspects of P. mirabilis UTI progression: fimbria-mediated attachment to the urinary tract, and flagella-mediated motility. Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) was used for the first time in a CAUTI pathogen to probe for in vivo direct targets of MrpJ. ChIP-seq revealed 81 78 direct MrpJ targets, including genes for motility, fimbriae and a type VI secretion system (T6SS), and the putative MrpJ binding sequence ACnCnnnnnnnGnGT.
Project description:This series of microarrays compares gene expression by the bacterial pathogen Proteus mirabilis when the transcriptional regulator mrpJ is deleted or induced to levels found during experimental urinary tract infection. The enteric bacterium Proteus mirabilis is associated with a significant number of catheter-associated urinary tract infections. Strict regulation of the antagonistic processes of adhesion and motility, mediated by fimbriae and flagella, respectively, is essential for successful disease progression. Previously, the transcriptional regulator MrpJ, which is encoded by the mrp fimbrial operon, has been shown to repress both swimming and swarming motility. Here we show that MrpJ affects a wide array of cellular processes beyond adherence and motility. Microarray analysis found that expression of mrpJ mimicking expression levels that occur during UTI leads to differential expression of 217 genes related to, among others, bacterial virulence, type VI secretion and metabolism. We probed the molecular mechanism of transcriptional regulation through MrpJ using reporter assays and chromatin immunoprecipitation (ChIP). Two virulence-associated target genes, the flagellar master regulator flhDC and mrp itself, appear to be regulated through a binding site proximal to the transcriptional start, complemented by a more distantly situated enhancer site. Furthermore, an mrpJ deletion mutant colonized the bladders of mice at significantly lower levels in a transurethral model of infection. Additionally, we observe that mrpJ is widely conserved in a collection of recent clinical isolates, leading us to conclude that our results elucidate an unanticipated role of MrpJ as a global regulator of P. mirabilis virulence. Four biological replicates were analyzed for each set of arrays (P. mirabilis HI4320 wild type vs. ΔmrpJ, and vector pLX3607 vs. mrpJ plasmid pLX3805).
Project description:Proteus mirabilis is a primary cause of complicated urinary tract infections (UTI). Surprisingly, iron acquisition systems have been poorly characterized in this uropathogen despite the urinary tract being iron-limited. In this report the transcriptome of strain HI4320, cultured under iron limitation, was examined using microarray analysis. Of genes upregulated at least 2-fold, 45 were statistically significant and comprise 21 putative iron-regulated systems. Two of these systems, PMI0229-0239 and PMI2596-2605, are organized in operons and appear to encode siderophore biosynthesis genes. Five microarrays comparing P. mirabilis HI4320 cultured in LB broth to P. mirabilis cultured in LB broth + 15 uM Desferal (an iron chelator) were analyzed. All five arrays are biological replicates; arrays #2 and 4 are dye swaps.
Project description:The enteric bacterium Proteus mirabilis is a common cause of complicated urinary tract infections. In the study, microrarrays were used to analyze P. mirabilis gene expression in vivo from experimentally infected mice. Urine was collected at 1, 3, and 7d postinfection, and RNA was isolated from bacteria in the urine for transcriptional analysis. Across 9 microarrays, 471 genes were upregulated and 82 were downregulated in vivo compared to in vitro broth culture. Genes upregulated in vivo encoded MR/P fimbriae, urease, iron uptake systems, amino acid and peptide transporters, pyruvate metabolism, and portions of the TCA cycle. Flagella were downregulated. Ammonia assimilation gene glnA (glutamine synthetase) was repressed in vivo while gdhA (glutamate dehydrogenase) was upregulated in vivo. Contrary to our expectations, ammonia availability due to urease activity in P. mirabilis did not drive this gene expression. A gdhA mutant was growth-deficient in minimal medium with citrate as the sole carbon source, and loss of gdhA resulted in a significant fitness defect in the mouse model of urinary tract infection. Unlike Escherichia coli, which represses gdhA and upregulates glnA in vivo and cannot utilize citrate, the data suggest that P. mirabilis uses glutamate dehydrogenase to monitor carbon-nitrogen balance, and this ability contributes to the pathogenic potential of P. mirabilis in the urinary tract. Voided urine from female CBA/J mice infected with Proteus mirabilis was collected and pooled in RNA stabilizing reagent (RNAprotect). Urine was collected at 1, 3, and 7 d postinfection. RNA was isolated from urine and log-phase LB cultures, converted to cDNA, and labeled with CyDye. Three arrays were completed per time point (9 arrays total). Slides were scanned with a ScanArray Express microarray scanner (Perkin Elmer) at 10 μm resolution and quantified using ScanArray Express software. Resulting data were normalized by total intensity and median spot intensities were identified using MIDAS (v. 2.22) software.
Project description:This series of microarrays compares gene expression by the bacterial pathogen Proteus mirabilis when the transcriptional regulator mrpJ is deleted or induced to levels found during experimental urinary tract infection. The enteric bacterium Proteus mirabilis is associated with a significant number of catheter-associated urinary tract infections. Strict regulation of the antagonistic processes of adhesion and motility, mediated by fimbriae and flagella, respectively, is essential for successful disease progression. Previously, the transcriptional regulator MrpJ, which is encoded by the mrp fimbrial operon, has been shown to repress both swimming and swarming motility. Here we show that MrpJ affects a wide array of cellular processes beyond adherence and motility. Microarray analysis found that expression of mrpJ mimicking expression levels that occur during UTI leads to differential expression of 217 genes related to, among others, bacterial virulence, type VI secretion and metabolism. We probed the molecular mechanism of transcriptional regulation through MrpJ using reporter assays and chromatin immunoprecipitation (ChIP). Two virulence-associated target genes, the flagellar master regulator flhDC and mrp itself, appear to be regulated through a binding site proximal to the transcriptional start, complemented by a more distantly situated enhancer site. Furthermore, an mrpJ deletion mutant colonized the bladders of mice at significantly lower levels in a transurethral model of infection. Additionally, we observe that mrpJ is widely conserved in a collection of recent clinical isolates, leading us to conclude that our results elucidate an unanticipated role of MrpJ as a global regulator of P. mirabilis virulence.
Project description:The enteric bacterium Proteus mirabilis is a common cause of complicated urinary tract infections. In the study, microrarrays were used to analyze P. mirabilis gene expression in vivo from experimentally infected mice. Urine was collected at 1, 3, and 7d postinfection, and RNA was isolated from bacteria in the urine for transcriptional analysis. Across 9 microarrays, 471 genes were upregulated and 82 were downregulated in vivo compared to in vitro broth culture. Genes upregulated in vivo encoded MR/P fimbriae, urease, iron uptake systems, amino acid and peptide transporters, pyruvate metabolism, and portions of the TCA cycle. Flagella were downregulated. Ammonia assimilation gene glnA (glutamine synthetase) was repressed in vivo while gdhA (glutamate dehydrogenase) was upregulated in vivo. Contrary to our expectations, ammonia availability due to urease activity in P. mirabilis did not drive this gene expression. A gdhA mutant was growth-deficient in minimal medium with citrate as the sole carbon source, and loss of gdhA resulted in a significant fitness defect in the mouse model of urinary tract infection. Unlike Escherichia coli, which represses gdhA and upregulates glnA in vivo and cannot utilize citrate, the data suggest that P. mirabilis uses glutamate dehydrogenase to monitor carbon-nitrogen balance, and this ability contributes to the pathogenic potential of P. mirabilis in the urinary tract.
Project description:Proteus mirabilis is a primary cause of complicated urinary tract infections (UTI). Surprisingly, iron acquisition systems have been poorly characterized in this uropathogen despite the urinary tract being iron-limited. In this report the transcriptome of strain HI4320, cultured under iron limitation, was examined using microarray analysis. Of genes upregulated at least 2-fold, 45 were statistically significant and comprise 21 putative iron-regulated systems. Two of these systems, PMI0229-0239 and PMI2596-2605, are organized in operons and appear to encode siderophore biosynthesis genes.
Project description:Catheter-associated urinary tract infections (CAUTIs) account for over 30% of acute nosocomial infections in the U.S. and generate $340 million in healthcare costs annually. A major causative agent of CAUTIs is Proteus mirabilis, an understudied Gram-negative pathogen noted for its ability to form urinary stones via the activity of urease. Urease mutants cannot induce stones and are attenuated in a murine UTI model, indicating this enzyme is essential to P. mirabilis pathogenesis. The ability to induce urinary stone formation requires an active urease, a nickel metalloenzyme that hydrolyzes urea. This reaction produces ammonia as a byproduct, which can serve as a nitrogen source and weak base that raises the local pH. The resulting alkalinity induces the precipitation of polyvalent cations and anions to form stones. Expression of urease genes is activated by transcriptional regulator UreR in a urea-dependent manner. Thus, urease genes are highly expressed in the urinary tract where urea is abundant (~400 mM in human urine). Production of mature urease also requires the import of nickel into the cytoplasm and its incorporation into the urease apoenzyme. Urease accessory proteins primarily acquire nickel from the Ynt transporter and facilitate the incorporation of nickel to form mature urease. P. mirabilis encodes a second, low-affinity transport system (Nik) that can provide nickel when this metal is abundant. In this study, we identified UreR as the first defined regulator of nickel transport in P. mirabilis. We also offer evidence for direct regulation of the ynt promoter by UreR. Using bioinformatics, we identified UreR-regulated urease loci in 15 Morganellaceae family species across three genera. Additionally, we located two mobilized UreR-regulated urease loci that also encode the ynt transporter, implying that UreR regulation of ynt is a conserved regulatory relationship. Our study demonstrates that UreR regulates all genes required to produce mature urease, an essential virulence factor for P. mirabilis uropathogenesis.
Project description:Swarming motility by the urinary tract pathogen Proteus mirabilis has been a long-studied, but little understood phenomenon. On agar, a P. mirabilis colony grows outward in a bullseye pattern formed by consecutive waves of rapid swarming followed by consolidation into shorter cells. To examine differential gene expression in these growth phases, a microarray, constructed based on the completed genome sequence and annotation, was undertaken. RNA from 1) broth-cultured, or 2) swarming cells was extracted to assess transcription during each of these growth states.