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

Palaniyandi, Senthilkumar; Mitra, Arindam; Herren, Christopher D.; Lockatell, C. Virginia; Johnson, David E.; Zhu, Xiaoping; Mukhopadhyay, Suman

doi:10.1371/journal.pone.0031348

Cited by 46 publications

(40 citation statements)

References 58 publications

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“…Many of these enzymes contain N-terminal signal input domains to sense and integrate environmental cues. While some of these signals have been identified and include oxygen, NO, redox, light, and the availability of nutrients (15,21,(55)(56)(57)(58), the vast majority of input signals are unknown. It is thus not surprising that under controlled laboratory conditions, only a subset of these enzymes shows activity and contributes to known c-di-GMP-dependent cellular processes.…”

Section: Discussionmentioning

confidence: 99%

Expression and Genetic Activation of Cyclic Di-GMP-Specific Phosphodiesterases in Escherichia coli

et al. 2016

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Intracellular levels of the bacterial second messenger cyclic di-GMP (c-di-GMP) are controlled by antagonistic activities of diguanylate cyclases and phosphodiesterases. The phosphodiesterase PdeH was identified as a key regulator of motility in Escherichia coli, while deletions of any of the other 12 genes encoding potential phosphodiesterases did not interfere with motility. To analyze the roles of E. coli phosphodiesterases, we demonstrated that most of these proteins are expressed under laboratory conditions. We next isolated suppressor mutations in six phosphodiesterase genes, which reinstate motility in the absence of PdeH by reducing cellular levels of c-di-GMP. Expression of all mutant alleles also led to a reduction of biofilm formation. Thus, all of these proteins are bona fide phosphodiesterases that are capable of interfering with different c-di-GMP-responsive output systems by affecting the global c-di-GMP pool. This argues that E. coli possesses several phosphodiesterases that are inactive under laboratory conditions because they lack appropriate input signals. Finally, one of these phosphodiesterases, PdeL, was studied in more detail. We demonstrated that this protein acts as a transcription factor to control its own expression. Motile suppressor alleles led to a strong increase of PdeL activity and elevated pdeL transcription, suggesting that enzymatic activity and transcriptional control are coupled. In agreement with this, we showed that overall cellular levels of c-di-GMP control pdeL transcription and that this control depends on PdeL itself. We thus propose that PdeL acts both as an enzyme and as a c-di-GMP sensor to couple transcriptional activity to the c-di-GMP status of the cell. IMPORTANCEMost bacteria possess multiple diguanylate cyclases and phosphodiesterases. Genetic studies have proposed that these enzymes show signaling specificity by contributing to distinct cellular processes without much cross talk. Thus, spatial separation of individual c-di-GMP signaling units was postulated. However, since most cyclases and phosphodiesterases harbor N-terminal signal input domains, it is equally possible that most of these enzymes lack their activating signals under laboratory conditions, thereby simulating signaling specificity on a genetic level. We demonstrate that a subset of E. coli phosphodiesterases can be activated genetically to affect the global c-di-GMP pool and thus influence different c-di-GMP-dependent processes. Although this does not exclude spatial confinement of individual phosphodiesterases, this study emphasizes the importance of environmental signals for activation of phosphodiesterases.

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Section: Discussionmentioning

confidence: 99%

Expression and Genetic Activation of Cyclic Di-GMP-Specific Phosphodiesterases in Escherichia coli

et al. 2016

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“…Lipopolysaccharide (LPS) extraction was performed as described previously (23). In short, bacteria were cultured in LB under static conditions for 48 h at 37°C in the presence of 0.5 mM IPTG and normalized to an OD 600 of 1, and LPS was extracted using an LPS extraction kit (Intron Biotechnology, Boca Raton, FL) according to the manufacturer's protocol.…”

Section: Methodsmentioning

confidence: 99%

PafR, a Novel Transcription Regulator, Is Important for Pathogenesis in Uropathogenic Escherichia coli

et al. 2014

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The metV genomic island in the chromosome of uropathogenic Escherichia coli (UPEC) encodes a putative transcription factor and a sugar permease of the phosphotransferase system (PTS), which are predicted to compose a Bgl-like sensory system. The presence of these two genes, hereby termed pafR and pafP, respectively, has been previously shown to correlate with isolates causing clinical syndromes. We show here that deletion of both genes impairs the ability of the resulting mutant to infect the CBA/J mouse model of ascending urinary tract infection compared to that of the parent strain, CFT073. Expressing the two genes in trans in the two-gene knockout mutant complemented full virulence. Deletion of either gene individually generated the same phenotype as the double knockout, indicating that both pafR and pafP are important to pathogenesis. We screened numerous environmental conditions but failed to detect expression from the promoter that precedes the paf genes in vitro, suggesting that they are in vivo induced (ivi). Although PafR is shown here to be capable of functioning as a transcriptional antiterminator, its targets in the UPEC genome are not known. Using microarray analysis, we have shown that expression of PafR from a heterologous promoter in CFT073 affects expression of genes related to bacterial virulence, biofilm formation, and metabolism. Expression of PafR also inhibits biofilm formation and motility. Taken together, our results suggest that the paf genes are implicated in pathogenesis and that PafR controls virulence genes, in particular biofilm formation genes. U rinary tract infection (UTI) is the most common form of extraintestinal bacterial infection acquired by humans, and uropathogenic Escherichia coli (UPEC) is the most common cause for UTI (1) (2). UPEC colonizes the bladder but may subsequently ascend the ureters and establish a secondary infection in the kidney. Left untreated, UPEC can elicit serious complications, including septicemia and death. Up to 30% of patients with UTI experience recurrent episodes (3). Only a few serogroups of E. coli cause a high proportion of infections. The UPEC strain CFT073, originally isolated from the blood and urine of a patient with acute pyelonephritis (4), is considered a prototype UPEC strain (5, 6). The virulence of CFT073 has been reproduced in the CBA mouse model of ascending UTI (4), where it can cause acute pyelonephritis (7).Sequencing of the CFT073 genome revealed that many of the open reading frames encode hypothetical or putative proteins (8), suggesting that many virulence determinants that play a role in UTI pathogenesis are still unknown. Using comparative genomic hybridization analysis of a panel of uropathogenic and fecal/commensal E. coli isolates, 131 genes were found to be present only in UPEC strains (9). The large number of hypothetical and unannotated genes among these UPEC-specific genes reinforces the notion that many urovirulence factors remain uncharacterized. Significantly, the UPEC-specific genes are not necessarily typical u...

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“…Uropathogenic E. coli (UPEC) strains commonly cause urinary tract infections, where they replicate in intracellular and extracellular locations with the help of a battery of virulence factors that include fimbriae, toxins, and iron siderophores (323). The BarA/UvrY TCS and CsrA have been implicated in regulating UPEC virulence in animal models and virulence factors expressed in vitro, although the mechanisms for these effects have not been determined (324)(325)(326).…”

mentioning

confidence: 99%

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Vakulskas

Potts

Babitzke

et al. 2015

Microbiol Mol Biol Rev

302

400

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SUMMARY Most bacterial pathogens have the remarkable ability to flourish in the external environment and in specialized host niches. This ability requires their metabolism, physiology, and virulence factors to be responsive to changes in their surroundings. It is no surprise that the underlying genetic circuitry that supports this adaptability is multilayered and exceedingly complex. Studies over the past 2 decades have established that the CsrA/RsmA proteins, global regulators of posttranscriptional gene expression, play important roles in the expression of virulence factors of numerous proteobacterial pathogens. To accomplish these tasks, CsrA binds to the 5′ untranslated and/or early coding regions of mRNAs and alters translation, mRNA turnover, and/or transcript elongation. CsrA activity is regulated by noncoding small RNAs (sRNAs) that contain multiple CsrA binding sites, which permit them to sequester multiple CsrA homodimers away from mRNA targets. Environmental cues sensed by two-component signal transduction systems and other regulatory factors govern the expression of the CsrA-binding sRNAs and, ultimately, the effects of CsrA on secretion systems, surface molecules and biofilm formation, quorum sensing, motility, pigmentation, siderophore production, and phagocytic avoidance. This review presents the workings of the Csr system, the paradigm shift that it generated for understanding posttranscriptional regulation, and its roles in virulence networks of animal and plant pathogens.

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

Cited by 46 publications

References 58 publications

Expression and Genetic Activation of Cyclic Di-GMP-Specific Phosphodiesterases in Escherichia coli

Expression and Genetic Activation of Cyclic Di-GMP-Specific Phosphodiesterases in Escherichia coli

PafR, a Novel Transcription Regulator, Is Important for Pathogenesis in Uropathogenic Escherichia coli

Regulation of Bacterial Virulence by Csr (Rsm) Systems

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