Regulation of type 1 fimbriae synthesis and biofilm formation by the transcriptional regulator LrhA of Escherichia coli
Type 1 fimbriae ofEscherichia colifacilitate 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 oflrhAresults in an increased expression of structural components of type 1 fimbriae.In vitro, LrhA bound to the promoter regions of the twofimrecombinases (FimB and FimE) that catalyse the inversion of thefimApromoter, and to the invertible element itself. TranslationallacZfusions with these genes and quantification offimEtranscript le…
LrhA as a new transcriptional key regulator of flagella, motility and chemotaxis genes in Escherichia coli
The function of the LysR-type regulator LrhA of Escherichia coli was defined by comparing whole-genome mRNA profiles from wild-type E. coli and an isogenic lrhA mutant on a DNA microarray. In the lrhA mutant, a large number (48) of genes involved in flagellation, motility and chemotaxis showed relative mRNA abundances increased by factors between 3 and 80. When a representative set of five flagellar, motility and chemotaxis genes was tested in lacZ reporter gene fusions, similar factors for derepression were found in the lrhA mutant. In gel retardation experiments, the LrhA protein bound specifically to flhD and lrhA promoter DNA (apparent K-D approximate to 20 nM), whereas the promoters of…