title: RosE represses Std fimbrial expression in Salmonella enterica serotype Typhimurium.
abstract: The Salmonella enterica serotype Typhimurium (S. typhimurium) genome contains a large repertoire of putative fimbrial operons that remain poorly characterized because they are not expressed in vitro. In this study, insertions that induced expression of the putative stdABCD fimbrial operon were identified from a random bank of transposon mutants by screening with immuno-magnetic particles for ligand expression (SIMPLE). Transposon insertions upstream of csgC and lrhA or within dam, setB and STM4463 (renamed rosE) resulted in expression of StdA and its assembly into fimbrial filaments on the cell surface. RosE is a novel negative regulator of Std fimbrial expression as indicated by its repression of a std::lacZ reporter construct and by binding of the purified protein to a DNA region upstream of the stdA start codon. Expression of Std fimbriae in the rosE mutant resulted in increased attachment of S. typhimurium to human colonic epithelial cell lines (T-84 and CaCo-2). A rosE mutant exhibited a reduced ability to compete with virulent S. typhimurium for colonization of murine organs, while no defect was observed when both competing strains carried a stdAB deletion. These data suggest that a tight control of Std fimbrial expression mediated by RosE is required during host pathogen interaction.
authors.affiliation: Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Ave., Davis, CA 95616-8645, USA.
authors.forename: Daniela
authors.initials: D
authors.lastname: Chessa
authors.forename: Maria G
authors.initials: MG
authors.lastname: Winter
authors.forename: Sean-Paul
authors.initials: SP
authors.lastname: Nuccio
authors.forename: Cagla
authors.initials: C
authors.lastname: Tükel
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Bäumler
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D045744:Cell Line, Tumor; D003106:Colon / Q000166:cytology / Q000382:microbiology; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015536:Down-Regulation; D024202:Electrophoretic Mobility Shift Assay; D004847:Epithelial Cells / Q000382:microbiology; D036781:Fimbriae Proteins / Q000235:genetics* / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D054884:Host-Pathogen Interactions; D006801:Humans; D051379:Mice; D016254:Mutagenesis, Insertional; D009876:Operon; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism*; D012481:Salmonella Infections, Animal / Q000382:microbiology; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D036781:Fimbriae Proteins