title: Expression of colonization factor CS5 of enterotoxigenic Escherichia coli (ETEC) is enhanced in vivo and by the bile component Na glycocholate hydrate.
abstract: Enterotoxigenic Escherichia coli (ETEC) is an important cause of acute watery diarrhoea in developing countries. Colonization factors (CFs) on the bacterial surface mediate adhesion to the small intestinal epithelium. Two of the most common CFs worldwide are coli surface antigens 5 and 6 (CS5, CS6). In this study we investigated the expression of CS5 and CS6 in vivo, and the effects of bile and sodium bicarbonate, present in the human gut, on the expression of CS5. Five CS5+CS6 ETEC isolates from adult Bangladeshi patients with acute diarrhoea were studied. The level of transcription from the CS5 operon was approximately 100-fold higher than from the CS6 operon in ETEC bacteria recovered directly from diarrhoeal stool without sub-culturing (in vivo). The glyco-conjugated primary bile salt sodium glycocholate hydrate (NaGCH) induced phenotypic expression of CS5 in a dose-dependent manner and caused a 100-fold up-regulation of CS5 mRNA levels; this is the first description of NaGCH as an enteropathogenic virulence inducer. The relative transcription levels from the CS5 and CS6 operons in the presence of bile or NaGCH in vitro were similar to those in vivo. Another bile salt, sodium deoxycholate (NaDC), previously reported to induce enteropathogenic virulence, also induced expression of CS5, whereas sodium bicarbonate did not.
authors.affiliation: Institute of Biomedicine, Department of Microbiology and Immunology, University of Gothenburg, Göteborg, Sweden. matilda.nicklasson@microbio.gu.se
authors.forename: Matilda
authors.initials: M
authors.lastname: Nicklasson
authors.forename: Åsa
authors.initials: Å
authors.lastname: Sjöling
authors.forename: Astrid
authors.initials: A
authors.lastname: von Mentzer
authors.forename: Firdausi
authors.initials: F
authors.lastname: Qadri
authors.forename: Ann-Mari
authors.initials: AM
authors.lastname: Svennerholm
mesh_terms: D001647:Bile Acids and Salts / Q000494:pharmacology*; D003967:Diarrhea / Q000382:microbiology; D054307:Enterotoxigenic Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005243:Feces / Q000382:microbiology; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D017693:Sodium Bicarbonate / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D001647:Bile Acids and Salts; D029968:Escherichia coli Proteins; D012333:RNA, Messenger; D036781:Fimbriae Proteins; D017693:Sodium Bicarbonate