title: The fimbriae activator MatA switches off motility in Escherichia coli by repression of the flagellar master operon flhDC.
abstract: Flagella provide advantages to Escherichia coli by facilitating taxis towards nutrients and away from unfavourable niches. On the other hand, flagellation is an energy sink to the bacterial cell, and flagella also stimulate host innate inflammatory responses against infecting bacteria. The flagellar assembly pathway is ordered and under a complex regulatory circuit that involves three classes of temporally regulated promoters as well as the flagellar master regulator FlhD(4)C(2). We report here that transcription of the flhDC operon from the class 1 promoter is under negative regulation by MatA, a key activator of the common mat (or ecp) fimbria operon that enhances biofilm formation by E. coli. Ectopic expression of MatA completely precluded motility and flagellar synthesis in the meningitis-associated E. coli isolate IHE 3034. Northern blotting, analysis of chromosomal promoter-lacZ fusions and electrophoretic mobility shift assays revealed an interaction between MatA and the flhDC promoter region that apparently repressed flagellum biosynthesis. However, inactivation of matA in the chromosome of IHE 3034 had only a minor effect on flagellation, which underlines the complexity of regulatory signals that promote flagellation in E. coli. We propose that the opposite regulatory actions of MatA on mat and on flhDC promoters advance the adaptation of E. coli from a planktonic to an adhesive lifestyle.
authors.affiliation: Division of General Microbiology, Department of Biosciences, FI-00014 University of Helsinki, Finland.
authors.forename: Timo A
authors.initials: TA
authors.lastname: Lehti
authors.affiliation: Institute for Molecular Biology of Infectious Diseases, Julius-Maximilians-University Würzburg, D-97080 Würzburg, Germany.
authors.forename: Philippe
authors.initials: P
authors.lastname: Bauchart
authors.affiliation: Institute for Hygiene, University of Münster, D-48149 Münster, Germany.|Institute for Molecular Biology of Infectious Diseases, Julius-Maximilians-University Würzburg, D-97080 Würzburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Dobrindt
authors.affiliation: Division of General Microbiology, Department of Biosciences, FI-00014 University of Helsinki, Finland.
authors.forename: Timo K
authors.initials: TK
authors.lastname: Korhonen
authors.affiliation: Division of General Microbiology, Department of Biosciences, FI-00014 University of Helsinki, Finland.
authors.forename: Benita
authors.initials: B
authors.lastname: Westerlund-Wikström
mesh_terms: D015536:Down-Regulation; D004926:Escherichia coli / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D015534:Trans-Activators; C090552:flhC protein, E coli; C090553:flhD protein, E coli