Distant cis‐active sequences and sialic acid control the expression of fimB in Escherichia coli K‐12

Summary 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....

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Published in:Molecular microbiology 2003-08, Vol.49 (4), p.1109-1118
Main Authors: El‐Labany, Sammia, Sohanpal, Baljinder K., Lahooti, Maryam, Akerman, Robert, Blomfield, Ian C.
Format: Article
Language:English
Subjects:
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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Summary:Summary 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.
ISSN:0950-382X
1365-2958
DOI:10.1046/j.1365-2958.2003.03624.x