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Integrated regulatory responses of fimB to N-acetylneuraminic (sialic) acid and GlcNAc in Escherichia coli K-12.

Sohanpal, Baljinder K., El-Labany, Sammia, Lahooti, Maryam, Plumbridge, Jacqueline A., Blomfield, Ian C. (2004) Integrated regulatory responses of fimB to N-acetylneuraminic (sialic) acid and GlcNAc in Escherichia coli K-12. Proceedings of the National Academy of Sciences of the United States of America, 101 (46). pp. 16322-16327. E-ISSN 1091-6490. (doi:10.1073/pnas.0405821101) (Access to this publication is currently restricted. You may be able to access a copy if URLs are provided) (KAR id:19)

Language: English

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Bacterial-host attachment by means of bacterial adhesins is a key step in host colonization. Phase variation (reversible on-off switching) of the type 1 fimbrial adhesin of Escherichia coli involves a DNA inversion catalyzed by FimB (switching in either direction) or FimE (mainly on-to-off switching). fimB is separated from the divergent yjhATS operon by a large (1.4 kbp) intergenic region. Short ( approximately 28 bp) cis-active elements (regions 1 and 2) close to yjhA stimulate fimB expression and are required for sialic acid (Neu(5)Ac) sensitivity of its expression [El-Labany, S., Sohanpal, B. K., Lahooti, M., Akerman, R. & Blomfield, I. C. (2003) Mol. Microbiol. 49, 1109-1118]. Here, we show that whereas NanR, a sialic acid-response regulator, binds to region 1, NagC, a GlcNAc-6P-responsive protein, binds to region 2 instead. The NanR- and NagC-binding sites lie adjacent to deoxyadenosine methylase (Dam) methylation sites (5'-GATC) that are protected from modification, and the two regulators are shown to be required for methylation protection at regions 1 and 2, respectively. Mutations in nanR and nagC diminish fimB expression, and both fimB expression and FimB recombination are inhibited by GlcNAc (3- and >35-fold, respectively). Sialic acid catabolism generates GlcNAc-6-P, and whereas GlcNAc disrupts methylation protection by NagC alone, Neu(5)Ac inhibits the protection mediated by both NanR and NagC as expected. Type 1 fimbriae are proinflammatory, and host defenses enhance the release of both Neu(5)Ac and GlcNAc by a variety of mechanisms. Inhibition of type 1 fimbriation by these amino sugars may thus help balance the interaction between E. coli and its hosts.

Item Type: Article
DOI/Identification number: 10.1073/pnas.0405821101
Subjects: Q Science
Divisions: Faculties > Sciences > School of Biosciences > Biomedical Research Group
Depositing User: Susan Davies
Date Deposited: 19 Dec 2007 17:45 UTC
Last Modified: 28 May 2019 13:34 UTC
Resource URI: (The current URI for this page, for reference purposes)
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