Event Abstract Back to Event Nitric oxide inhibits adhesion in Enterohemorrhagic Escherichia coli O157:H7 Priscilla Branchu1* 1 INRA, Unité de recherche Microbiologie, France Priscilla BRANCHU1, Marjolaine Vareille1, Sébastien CREPIN2, Josée Harel2, Alain P. GOBERT1, Christine MARTIN1 1UR454 Microbiologie, INRA Clermont-Ferrand-Theix, 63122 Saint-Genès-Champanelle, France. 2Faculté de médecine vétérinaire, Université de Montréal, Ste-Hyacinthe J2S 7C6, Canada. Enterohemorrhagic Escherichia coli O157:H7 is a major foodborne pathogen causing severe disease in humans like the hemolytic uremic syndrome. As antibiotics are contraindicated to fight the infection, a deep knowledge of EHEC-host interaction is required to suggest other therapeutic measures. E. coli O157:H7 adheres to epithelial cells of the intestinal mucosa through a type three secretion system encoded by the locus of enterocyte effacement (LEE). The LEE is organized in at least five operons; the first one, LEE1, encodes for the main transcriptional activator of the other LEE operons, Ler. EHEC synthesizes and releases in the gut the Shiga toxins Stx1 and/or Stx2, which are responsible for the hemorrhagic symptoms of the disease. We have previously shown that nitric oxide (NO), an effector of the innate immune response of the intestinal mucosa, inhibits Shiga-toxin production1. Therefore, we investigated the influence of NO on LEE expression. Microarray experiments indicated that NO represses LEE4 and LEE5, but not LEE1 expression, and activates gadE and gadX expression. Using isogenic mutants and over expression of the gadE and gadX genes, we showed that GadE and GadX repress LEE expression. By chromatin immunoprecipitation, we demonstrated that NO promotes GadE and GadX binding on the LEE4 and LEE5, but not LEE1 promoters. We proposed a model in which NO represses LEE4 and LEE5 transcription independently of Ler by altering the binding affinity of GadE and GadX on the LEE4 and LEE5 promoters. In accordance with these results, we demonstrated that exogenous NO and endogenous NO produced by activated Hct-8 cells inhibit E. coli O157:H7 adhesion on these intestinal epithelial cells. Vareille M, de Sablet T, Hindré T, Martin C and Gobert AP. 2007. Nitric oxide inhibits Shiga-toxin synthesis by enterohemorrhagic Escherichia coli. Proc. Natl. Acad. Sci. USA. 104: 10199-10204. Keywords: EHEC O157:H7, host interaction, locus of enterotrocyte effacement, nitric oxid Conference: ECMIS - E. coli and the Mucosal Immune System : Interaction, Modulation and Vaccination, Ghent, Belgium, 2 Jul - 5 Jul, 2011. Presentation Type: Oral Presentation Topic: Virulence factors and influence on innate and/or adaptive immunity Citation: Branchu P (2011). Nitric oxide inhibits adhesion in Enterohemorrhagic Escherichia coli O157:H7. Front. Immunol. Conference Abstract: ECMIS - E. coli and the Mucosal Immune System : Interaction, Modulation and Vaccination. doi: 10.3389/conf.fimmu.2011.01.00012 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 26 Sep 2011; Published Online: 03 Oct 2011. * Correspondence: Miss. Priscilla Branchu, INRA, Unité de recherche Microbiologie, Saint-genès-champanelle, 63122, France, priscilla.branchu@clermont.inra.fr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Priscilla Branchu Google Priscilla Branchu Google Scholar Priscilla Branchu PubMed Priscilla Branchu Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.