| Autor: |
El-Labany S; Research School of Biosciences, University of Kent, Kent CT2 7NJ, UK., Sohanpal BK, Lahooti M, Akerman R, Blomfield IC |
| Jazyk: |
angličtina |
| Zdroj: |
Molecular microbiology [Mol Microbiol] 2003 Aug; Vol. 49 (4), pp. 1109-18. |
| DOI: |
10.1046/j.1365-2958.2003.03624.x |
| Abstrakt: |
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. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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