title: Lrp stimulates phase variation of type 1 fimbriation in Escherichia coli K-12.
abstract: The phase variation of type 1 fimbriation in Escherichia coli is associated with the inversion of a short DNA element. This element (switch) acts in cis to control transcription of fimA, the major fimbrial subunit gene. Thus, fimA is transcribed when the switch is in one orientation (the on orientation) but not the other (the off orientation). The fim inversion requires either fimB (on-to-off or off-to-on inversion) or fimE (on-to-off inversion only), as well as integration host factor, and is also influenced by the abundant DNA-binding protein H-NS. Here we report that an additional gene, lrp, a factor known to influence the expression of both Pap and K99 fimbriae, is also required for normal activity of the fim switch. The frequencies of both fimB-promoted and fimE-promoted inversions, and consequently the phase variation of type 1 fimbriation, are lower in lrp mutants. Lrp affects slightly the transcription of both fimB (which is increased) and fimE (which is decreased). We believe that these alterations in fimB and fimE transcription alone are unlikely to account for the sharp reduction in switching found in lrp mutants.
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109.
authors.forename: I C
authors.initials: IC
authors.lastname: Blomfield
authors.forename: P J
authors.initials: PJ
authors.lastname: Calie
authors.forename: K J
authors.initials: KJ
authors.lastname: Eberhardt
authors.forename: M S
authors.initials: MS
authors.lastname: McClain
authors.forename: B I
authors.initials: BI
authors.lastname: Eisenstein
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D007446:Chromosome Inversion; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D010861:Fimbriae, Bacterial / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D005812:Genes, Switch / Q000235:genetics; D005816:Genetic Complementation Test; D007763:Lac Operon / Q000235:genetics; D051756:Leucine-Responsive Regulatory Protein; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010641:Phenotype; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C497278:Lrp protein, E coli; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D051756:Leucine-Responsive Regulatory Protein; D001616:beta-Galactosidase