PhoB activates Escherichia coli O157:H7 virulence factors in response to inorganic phosphate limitation. 2014

Samuel Mohammed Chekabab, and Grégory Jubelin, and Charles M Dozois, and Josée Harel
Research Group on Infectious Diseases of Swine, Montreal University, Faculty of Veterinary Medicine, Saint-Hyacinthe, Québec, Canada.

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.

UI MeSH Term Description Entries
D010710 Phosphates Inorganic salts of phosphoric acid. Inorganic Phosphate,Phosphates, Inorganic,Inorganic Phosphates,Orthophosphate,Phosphate,Phosphate, Inorganic
D010750 Phosphoproteins Phosphoprotein
D011401 Promoter Regions, Genetic DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes. rRNA Promoter,Early Promoters, Genetic,Late Promoters, Genetic,Middle Promoters, Genetic,Promoter Regions,Promoter, Genetic,Promotor Regions,Promotor, Genetic,Pseudopromoter, Genetic,Early Promoter, Genetic,Genetic Late Promoter,Genetic Middle Promoters,Genetic Promoter,Genetic Promoter Region,Genetic Promoter Regions,Genetic Promoters,Genetic Promotor,Genetic Promotors,Genetic Pseudopromoter,Genetic Pseudopromoters,Late Promoter, Genetic,Middle Promoter, Genetic,Promoter Region,Promoter Region, Genetic,Promoter, Genetic Early,Promoter, rRNA,Promoters, Genetic,Promoters, Genetic Middle,Promoters, rRNA,Promotor Region,Promotors, Genetic,Pseudopromoters, Genetic,Region, Genetic Promoter,Region, Promoter,Region, Promotor,Regions, Genetic Promoter,Regions, Promoter,Regions, Promotor,rRNA Promoters
D006367 HeLa Cells The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for, among other things, VIRUS CULTIVATION and PRECLINICAL DRUG EVALUATION assays. Cell, HeLa,Cells, HeLa,HeLa Cell
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D014157 Transcription Factors Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process. Transcription Factor,Factor, Transcription,Factors, Transcription
D044404 Genomic Islands Distinct units in some bacterial, bacteriophage or plasmid GENOMES that are types of MOBILE GENETIC ELEMENTS. Encoded in them are a variety of fitness conferring genes, such as VIRULENCE FACTORS (in "pathogenicity islands or islets"), ANTIBIOTIC RESISTANCE genes, or genes required for SYMBIOSIS (in "symbiosis islands or islets"). They range in size from 10 - 500 kilobases, and their GC CONTENT and CODON usage differ from the rest of the genome. They typically contain an INTEGRASE gene, although in some cases this gene has been deleted resulting in "anchored genomic islands". Pathogenicity Islands,Anchored Genomic Islands,Genomic Islets,Pathogenicity Islets,Symbiosis Islands,Symbiosis Islets,Anchored Genomic Island,Genomic Island,Genomic Island, Anchored,Genomic Islands, Anchored,Genomic Islet,Island, Anchored Genomic,Island, Genomic,Island, Pathogenicity,Island, Symbiosis,Islands, Anchored Genomic,Islands, Genomic,Islands, Pathogenicity,Islands, Symbiosis,Islet, Genomic,Islet, Pathogenicity,Islet, Symbiosis,Islets, Genomic,Islets, Pathogenicity,Islets, Symbiosis,Pathogenicity Island,Pathogenicity Islet,Symbiosis Island,Symbiosis Islet
D019453 Escherichia coli O157 A verocytotoxin-producing serogroup belonging to the O subfamily of Escherichia coli which has been shown to cause severe food-borne disease. A strain from this serogroup, serotype H7, which produces SHIGA TOXINS, has been linked to human disease outbreaks resulting from contamination of foods by E. coli O157 from bovine origin. E coli O157,E coli O157-H7,Escherichia coli O157-H7
D020869 Gene Expression Profiling The determination of the pattern of genes expressed at the level of GENETIC TRANSCRIPTION, under specific circumstances or in a specific cell. Gene Expression Analysis,Gene Expression Pattern Analysis,Transcript Expression Analysis,Transcriptome Profiling,Transcriptomics,mRNA Differential Display,Gene Expression Monitoring,Transcriptome Analysis,Analyses, Gene Expression,Analyses, Transcript Expression,Analyses, Transcriptome,Analysis, Gene Expression,Analysis, Transcript Expression,Analysis, Transcriptome,Differential Display, mRNA,Differential Displays, mRNA,Expression Analyses, Gene,Expression Analysis, Gene,Gene Expression Analyses,Gene Expression Monitorings,Gene Expression Profilings,Monitoring, Gene Expression,Monitorings, Gene Expression,Profiling, Gene Expression,Profiling, Transcriptome,Profilings, Gene Expression,Profilings, Transcriptome,Transcript Expression Analyses,Transcriptome Analyses,Transcriptome Profilings,mRNA Differential Displays
D020895 Enterocytes Absorptive cells in the lining of the INTESTINAL MUCOSA. They are differentiated EPITHELIAL CELLS with apical MICROVILLI facing the intestinal lumen. Enterocytes are more abundant in the SMALL INTESTINE than in the LARGE INTESTINE. Their microvilli greatly increase the luminal surface area of the cell by 14- to 40 fold. Enterocyte

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