title: Control of acid resistance pathways of enterohemorrhagic Escherichia coli strain EDL933 by PsrB, a prophage-encoded AraC-like regulator.
abstract: Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes bloody diarrhea and hemolytic-uremic syndrome (HUS) and is the most prevalent E. coli serotype associated with food-borne illness worldwide. This pathogen is transmitted via the fecal-oral route and has a low infectious dose that has been estimated to be between 10 and 100 cells. We and others have previously identified three prophage-encoded AraC-like transcriptional regulators, PatE, PsrA, and PsrB in the EHEC O157:H7 EDL933 strain. Our analysis showed that PatE plays an important role in facilitating survival of EHEC under a number of acidic conditions, but the contribution of PsrA and PsrB to acid resistance (AR) was unknown. Here, we investigated the involvement of PsrA and PsrB in the survival of E. coli O157:H7 in acid. Our results showed that PsrB, but not PsrA, enhanced the survival of strain EDL933 under various acidic conditions. Transcriptional analysis using promoter-lacZ reporters and electrophoretic mobility shift assays demonstrated that PsrB activates transcription of the hdeA operon, which encodes a major acid stress chaperone, by interacting with its promoter region. Furthermore, using a mouse model, we showed that expression of PsrB significantly enhanced the ability of strain EDL933 to overcome the acidic barrier of the mouse stomach. Taken together, our results indicate that EDL933 acquired enhanced acid tolerance via horizontally acquired regulatory genes encoding transcriptional regulators that activate its AR machinery.
authors.affiliation: Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
authors.forename: Ji
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Russell
authors.affiliation: Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
authors.forename: Dianna M
authors.initials: DM
authors.lastname: Hocking
authors.affiliation: Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Bender
authors.affiliation: Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
authors.forename: Yogitha N
authors.initials: YN
authors.lastname: Srikhanta
authors.affiliation: Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
authors.forename: Marija
authors.initials: M
authors.lastname: Tauschek
authors.affiliation: Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia r.browne@unimelb.edu.au.
authors.forename: Roy M
authors.initials: RM
authors.lastname: Robins-Browne
mesh_terms: D000143:Acids / Q000633:toxicity*; D000818:Animals; D019677:Artificial Gene Fusion; D004269:DNA, Bacterial / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000235:genetics / Q000502:physiology / Q000821:virology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D008810:Mice, Inbred C57BL; D050296:Microbial Viability / Q000187:drug effects; D039002:Prophages / Q000235:genetics*; D011485:Protein Binding; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
chemical_list: D000143:Acids; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C000595459:PsrA protein, E coli; C000595460:PsrB protein, E coli; D014157:Transcription Factors; D001616:beta-Galactosidase