title: HtrA stress protein is involved in intramacrophagic replication of adherent and invasive Escherichia coli strain LF82 isolated from a patient with Crohn's disease.
abstract: Adherent and invasive Escherichia coli (AIEC) bacteria isolated from Crohn's disease patients are able to greatly replicate within macrophages without escaping from the phagosome and without inducing macrophage death. In the present study, evidence is provided that in AIEC strain LF82 the htrA gene encoding the stress protein HtrA is essential for intracellular replication within J774-A1 macrophages. Deletion of the htrA gene in strain LF82 induced increased sensitivity of the isogenic mutant to oxidative stress caused by hydrogen peroxide and a reduced rate of growth in an acid and nutrient-poor medium partly reproducing the microenvironment of the phagosome. In vitro experiments using an LF82 htrA gene promoter fusion with the lacZ gene revealed a 38-fold activation of the promoter in AIEC LF82 intramacrophagic bacteria. The CpxRA two-component signaling pathway was not involved in this activation. In addition, the activation of the LF82 htrA gene promoter was not observed in the nonpathogenic E. coli K-12 intramacrophagic bacteria, indicating that the AIEC LF82 genetic background is crucial for induction of htrA gene transcription during phagocytosis.
authors.affiliation: Pathogénie Bactérienne Intestinale, Laboratoire de Bactériologie, Université d'Auvergne, CBRV, 28 Place Henri Dunant, 63001 Clermont-Ferrand, France.
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Bringer
authors.forename: Nicolas
authors.initials: N
authors.lastname: Barnich
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Glasser
authors.forename: Olivier
authors.initials: O
authors.lastname: Bardot
authors.forename: Arlette
authors.initials: A
authors.lastname: Darfeuille-Michaud
mesh_terms: D002455:Cell Division / Q000235:genetics / Q000502:physiology*; D003424:Crohn Disease / Q000382:microbiology*; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008264:Macrophages / Q000382:microbiology*; D009154:Mutation; D018384:Oxidative Stress; D033903:Periplasmic Proteins / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic; D012697:Serine Endopeptidases / Q000235:genetics / Q000502:physiology*
chemical_list: D004251:DNA Transposable Elements; D006360:Heat-Shock Proteins; D033903:Periplasmic Proteins; C061682:DegP protease; D012697:Serine Endopeptidases