PMID:12890032
| Citation |
El-Labany, S, Sohanpal, BK, Lahooti, M, Akerman, R and Blomfield, IC (2003) Distant cis-active sequences and sialic acid control the expression of fimB in Escherichia coli K-12. Mol. Microbiol. 49:1109-18 |
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| 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. |
| Links | |
| Keywords |
DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; Escherichia coli/genetics; Escherichia coli/physiology; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Expression Regulation, Bacterial; Integrases/genetics; Integrases/metabolism; Mutation; Recombination, Genetic; Regulatory Sequences, Nucleic Acid; Sialic Acids/metabolism |
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