title: Regulation of type 1 fimbriae synthesis and biofilm formation by the transcriptional regulator LrhA of Escherichia coli.
abstract: Type 1 fimbriae of Escherichia coli facilitate attachment to the host mucosa and promote biofilm formation on abiotic surfaces. The transcriptional regulator LrhA, which is known as a repressor of flagellar, motility and chemotaxis genes, regulates biofilm formation and expression of type 1 fimbriae. Whole-genome expression profiling revealed that inactivation of lrhA results in an increased expression of structural components of type 1 fimbriae. In vitro, LrhA bound to the promoter regions of the two fim recombinases (FimB and FimE) that catalyse the inversion of the fimA promoter, and to the invertible element itself. Translational lacZ fusions with these genes and quantification of fimE transcript levels by real-time PCR showed that LrhA influences type 1 fimbrial phase variation, primarily via activation of FimE, which is required for the ON-to-OFF transition of the fim switch. Enhanced type 1 fimbrial expression as a result of lrhA disruption was confirmed by mannose-sensitive agglutination of yeast cells. Biofilm formation was stimulated by lrhA inactivation and completely suppressed upon LrhA overproduction. The effects of LrhA on biofilm formation were exerted via the changed levels of surface molecules, most probably both flagella and type 1 fimbriae. Together, the data show a role for LrhA as a repressor of type 1 fimbrial expression, and thus as a regulator of the initial stages of biofilm development and, presumably, bacterial adherence to epithelial host cells also.
authors.affiliation: Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg Universität Mainz, Becherweg 15, 55099 Mainz, Germany.
authors.forename: Caroline
authors.initials: C
authors.lastname: Blumer
authors.affiliation: Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg Universität Mainz, Becherweg 15, 55099 Mainz, Germany.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kleefeld
authors.affiliation: Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg Universität Mainz, Becherweg 15, 55099 Mainz, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Lehnen
authors.affiliation: Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg Universität Mainz, Becherweg 15, 55099 Mainz, Germany.
authors.forename: Margit
authors.initials: M
authors.lastname: Heintz
authors.affiliation: Institut für Molekulare Infektionsbiologie der Universität Würzburg, 97070 Würzburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Dobrindt
authors.affiliation: Institute of Medical Microbiology and Immunology, University of Pécs, 7624 Pécs, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Nagy
authors.affiliation: Institut für Molekulare Infektionsbiologie der Universität Würzburg, 97070 Würzburg, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Michaelis
authors.affiliation: Institute of Medical Microbiology and Immunology, University of Pécs, 7624 Pécs, Hungary.
authors.forename: Levente
authors.initials: L
authors.lastname: Emödy
authors.affiliation: Forschungszentrum Jülich, Institut für Biotechnologie I, 52425 Jülich, Germany.
authors.forename: Tino
authors.initials: T
authors.lastname: Polen
authors.affiliation: Institut für Mikrobiologie, Universität Regensburg, 93040 Regensburg, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Rachel
authors.affiliation: Forschungszentrum Jülich, Institut für Biotechnologie I, 52425 Jülich, Germany.
authors.forename: Volker F
authors.initials: VF
authors.lastname: Wendisch
authors.affiliation: Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg Universität Mainz, Becherweg 15, 55099 Mainz, Germany.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Unden
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology / Q000401:mortality; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D051379:Mice; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014552:Urinary Tract Infections / Q000382:microbiology / Q000401:mortality
chemical_list: D029968:Escherichia coli Proteins; C490682:LrhA protein, E coli; D014157:Transcription Factors