Novel members of the phosphate regulon in Escherichia coli O157:H7 identified using a whole-genome shotgun approach

Yoshida, Yusuke; Sugiyama, Shunsuke; Oyamada, Tomoya; Yokoyama, Katsushi; Makino, Kozo

doi:10.1016/j.gene.2012.03.064

Cited by 18 publications

(18 citation statements)

References 43 publications

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“…They showed that some of those genes are not related to Pi metabolism or utilization. This suggests that in response to environmental Pi stress, the Pho-regulon regulates genes involved not only in Pi homeostasis but also in other functions of E. coli O157: H7 (Yoshida et al, 2012).…”

Section: Factors Involved In Environmental Persistence Of E Coli O15mentioning

confidence: 99%

The ecological habitat and transmission ofEscherichia coliO157:H7

Chekabab

Paquin-Veillette

Dozois

et al. 2013

FEMS Microbiol Lett

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Since its first description in 1982, the zoonotic life-threatening Shiga toxin-producing Escherichia coli O157:H7 has emerged as an important food- and water-borne pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome in humans. In the last decade, increases in E. coli O157:H7 outbreaks were associated with environmental contamination in water and through fresh produce such as green leaves or vegetables. Both intrinsic (genetic adaptation) and extrinsic factors may contribute and help E. coli O157:H7 to survive in adverse environments. This makes it even more difficult to detect and monitor food and water safety for public health surveillance. E. coli O157:H7 has evolved in behaviors and strategies to persist in the environment.

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Section: Factors Involved In Environmental Persistence Of E Coli O15mentioning

confidence: 99%

The ecological habitat and transmission ofEscherichia coliO157:H7

Chekabab

Paquin-Veillette

Dozois

et al. 2013

FEMS Microbiol Lett

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“…PhoU has no evident role in Pi transport, but is required for control of the Pho regulon. In E. coli , there are at least 40 gene members of the Pho regulon that are primarily involved in phosphate assimilation and metabolism [6]–[9]. Transcription of all these genes is regulated in response to extracellular Pi concentrations via the TCS PhoB-R. During Pi limitation, the histidine-kinase PhoR phosphorylates PhoB.…”

Section: Introductionmentioning

confidence: 99%

PhoB Activates Escherichia coli O157:H7 Virulence Factors in Response to Inorganic Phosphate Limitation

Chekabab¹,

Jubelin²,

Dozois

et al. 2014

PLoS ONE

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Enterohemorrhagic Escherichia coli (EHEC), an emerging food- and water-borne hazard, is highly pathogenic to humans. In the environment, EHEC must survive phosphate (Pi) limitation. The response to such Pi starvation is an induction of the Pho regulon including the Pst system that senses Pi variation. The interplay between the virulence of EHEC, Pho-Pst system and environmental Pi remains unknown. To understand the effects of Pi deprivation on the molecular mechanisms involved in EHEC survival and virulence under Pho regulon control, we undertook transcriptome profiling of the EDL933 wild-type strain grown under high Pi and low Pi conditions and its isogenic ΔphoB mutant grown in low Pi conditions. The differentially expressed genes included 1067 Pi-dependent genes and 603 PhoB-dependent genes. Of these 131 genes were both Pi and PhoB-dependent. Differentially expressed genes that were selected included those involved in Pi homeostasis, cellular metabolism, acid stress, oxidative stress and RpoS-dependent stress responses. Differentially expressed virulence systems included the locus of enterocyte effacement (LEE) encoding the type-3 secretion system (T3SS) and its effectors, as well as BP-933W prophage encoded Shiga toxin 2 genes. Moreover, PhoB directly regulated LEE and stx2 gene expression through binding to specific Pho boxes. However, in Pi-rich medium, constitutive activation of the Pho regulon decreased LEE gene expression and reduced adherence to HeLa cells. Together, these findings reveal that EHEC has evolved a sophisticated response to Pi limitation involving multiple biochemical strategies that contribute to its ability to respond to variations in environmental Pi and to coordinating the virulence response.

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“…To cope with orthophosphate (P i ) shortage in natural environments, bacteria activate several systems associated with the process of uptake and assimilation of P i and organophosphates (phosphate esters and phosphonates). Most of these genes, collectively known as the PHO regulon, are strongly expressed under P i limitation (1,2,3). Transcription of the PHO regulon genes in Escherichia coli is controlled by the two-component system PhoB-PhoR.…”

mentioning

confidence: 99%

phoU Inactivation in Pseudomonas aeruginosa Enhances Accumulation of ppGpp and Polyphosphate

Almeida

Ortiz

Schneider

et al. 2015

Appl Environ Microbiol

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bInorganic polyphosphate (polyP) is a linear polymer composed of several molecules of orthophosphate (P i ) linked by energyrich phosphoanhydride bonds. In Pseudomonas aeruginosa, P i is taken up by the ABC transporter Pst, encoded by an operon consisting of five genes. The first four genes encode proteins involved in the transport of P i and the last gene of the operon, phoU, codes for a protein which exact function is unknown. We show here that the inactivation of phoU in P. aeruginosa enhanced P i removal from the medium and polyP accumulation. The phoU mutant also accumulated high levels of the alarmone guanosine tetraphosphate (ppGpp), which in turn increased the buildup of polyP. In addition, phoU inactivation had several pleiotropic effects, such as reduced growth rate and yield and increased sensitivity to antibiotics and stresses. However, biofilm formation was not affected by the phoU mutation. Inorganic phosphate (polyP) is an important macronutrient for all living beings, making up to 3% of bacterial dry weight. To cope with orthophosphate (P i ) shortage in natural environments, bacteria activate several systems associated with the process of uptake and assimilation of P i and organophosphates (phosphate esters and phosphonates). Most of these genes, collectively known as the PHO regulon, are strongly expressed under P i limitation (1, 2, 3). Transcription of the PHO regulon genes in Escherichia coli is controlled by the two-component system PhoB-PhoR. PhoR is the histidine kinase that phosphorylates PhoB which in turn activates the transcription of the PHO regulon genes by interacting with the PHO-box, a consensus sequence present at single or multiple copies at the Ϫ35 region of all PHO promoters (2). One of the most well-studied components of the PHO regulon is the pst operon. The four proximal genes of the operon, pstS, pstC, pstA, and pstB, encode a high-affinity P i transport system. PstS is a periplasmic P i -binding protein that captures and transfers P i molecules to the channel formed by the integral proteins PstC and PstA in the cytoplasmic membrane. PstB is an ATPase that provides the energy for transport (4). The last gene of the operon, phoU, encodes a protein whose exact function is unknown. All five proteins encoded by the pst operon act as repressors of the PHO regulon under conditions of P i excess. The mechanism of repression is still unclear, but null mutations in any pst gene (phoU included) result in the constitutive expression of the entire regulon (2).Pseudomonas aeruginosa is a gammaproteobacterium found in natural water reservoirs, soil, plants, and animals. In humans, it is an opportunistic pathogen, causing infections in immunocompromised and cystic fibrosis patients and is also associated with severe burn infections. P. aeruginosa carries a PHO regulon similar to that of E. coli, but it is not as well characterized. An in silico study predicted the presence of 73 PHO-boxes in the chromosome of strain PAO1 (5). The architectures of the pst operon of P. aeruginosa and E. c...

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Novel members of the phosphate regulon in Escherichia coli O157:H7 identified using a whole-genome shotgun approach

Cited by 18 publications

References 43 publications

The ecological habitat and transmission ofEscherichia coliO157:H7

The ecological habitat and transmission ofEscherichia coliO157:H7

PhoB Activates Escherichia coli O157:H7 Virulence Factors in Response to Inorganic Phosphate Limitation

phoU Inactivation in Pseudomonas aeruginosa Enhances Accumulation of ppGpp and Polyphosphate

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