1. Distant cis-active sequences and sialic acid control the expression of fimB in Escherichia coli K-12.
- Author
-
El-Labany S, Sohanpal BK, Lahooti M, Akerman R, and Blomfield IC
- Subjects
- DNA-Binding Proteins genetics, Escherichia coli physiology, Escherichia coli Proteins genetics, Integrases genetics, Mutation, Recombination, Genetic, DNA-Binding Proteins metabolism, Escherichia coli genetics, Escherichia coli Proteins metabolism, Gene Expression Regulation, Bacterial, Integrases metabolism, Regulatory Sequences, Nucleic Acid, Sialic Acids metabolism
- Abstract
The phase variation of type 1 fimbriation in Escherichia coli is controlled by the inversion of a 314 bp element of DNA, determined by FimB (switching in both directions) or FimE (switching from the ON-to-OFF orientation predominantly), and influenced by auxiliary factors IHF, Lrp and H-NS. The fimB gene is separated from the divergently transcribed yjhATS operon by a large (1.4 kbp) intergenic region of unknown function. Here, we show that fimB expression is regulated by multiple cis-active sequences that lie far upstream (>600 bp) of the transcription start sites for the recombinase gene. Two regions characterized further (regions 1 and 2) show sequence identity, and each coincides with a methylation-protected Dam (5'-GATC) site. Regions 1 and 2 apparently control fimB expression by an antirepression mechanism that involves additional sequences proximal to yjhA. Region 1 encompasses a 27 bp DNA sequence conserved upstream of genes known (nanAT ) or suspected (yjhBC) to be involved in sialic acid metabolism, and we show that FimB expression and recombination are suppressed by N-acetylneuraminic acid. We propose that E. coli recognizes the amino sugars as a harbinger of potential host defence activation, and suppresses the expression of type 1 fimbriae in response.
- Published
- 2003
- Full Text
- View/download PDF