Lrp stimulates phase variation of type 1 fimbriation in Escherichia coli K-12.

Blomfield IC, Calie PJ, Eberhardt KJ, McClain MS, Eisenstein BI
J Bacteriol. 1993 175 (1): 27-36

PMID: 8093239 · PMCID: PMC196094 · DOI:10.1128/jb.175.1.27-36.1993

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.

MeSH Terms (20)

Bacterial Proteins Base Sequence beta-Galactosidase Chromosome Inversion Chromosome Mapping DNA-Binding Proteins Escherichia coli Escherichia coli Proteins Fimbriae, Bacterial Gene Expression Regulation, Bacterial Genes, Switch Genetic Complementation Test Lac Operon Leucine-Responsive Regulatory Protein Molecular Sequence Data Mutagenesis, Insertional Phenotype Recombinant Fusion Proteins Transcription, Genetic Transcription Factors

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