Control of Escherichia coli O157:H7 motility and biofilm formation by salicylate and decanoate: MarA/SoxS/Rob and pchE interactions

Authors: Uhlich, Gaylen; Smith, Heather; Gunther, Nereus - Jack; Ream, Amy

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2021
Publication Date: 1/25/2022
Citation: Uhlich, G.A., Koppenhofer, H.L., Gunther, N.W., Ream, A.R. 2022. Control of Escherichia coli O157:H7 motility and biofilm formation by salicylate and decanoate: MarA/SoxS/Rob and pchE interactions. Applied and Environmental Microbiology. 88(2). Article e0189121. https://doi.org/10.1128/AEM.01891-21.
DOI: https://doi.org/10.1128/AEM.01891-21

Interpretive Summary: Transcription factor (TF) proteins bind DNA and initiate RNA copies of nearby genes for protein production. In enterohemorrhagic strains of Escherichia coli (EHEC), curli fimbriae and flagella are surface structures that participate in bacterial movement and attachment to surfaces. Surfaces include those of cells lining human intestines and the surfaces of other bacteria, which link together to form stress-resistant communities (biofilm). The pchE TF controls curli and flagella production, whose expression levels affect biofilm formation and the initiation of disease. A method to control EHEC disease and biofilm formation would be to identify chemicals that control the expression of a different set of TFs that regulate pchE. In this study we identify MarA, SoxS and Rob, as TFs that regulate pchE and confirm that two inducers of those TFs, salicylate and decanoate, regulate EHEC flagella and curli.

Technical Abstract: Prophage-encoded Escherichia coli O157:H7 transcription factor (TF), PchE, inhibits biofilm formation and attachment to cultured epithelial cells by reducing curli fimbriae expression and increasing flagella expression. To identify pchE regulators that might be used as intervention strategies to reduce environmental persistence or host infections, we performed a computation search of O157:H7 strain PA20 pchE promoter sequences for binding sites used by known TFs. A common site shared by MarA/SoxS/Rob TFs was identified and typical MarA/Rob inducers salicylate and decanoate were tested for biofilm and motility effects. Sodium salicylate, a proven biofilm inhibitor, but not decanoate, strongly reduced O157:H7 biofilms by a pchE-independent mechanism. Both salicylate and decanoate enhanced O157:H7 motility dependent on pchE using media and at temperatures optimum for culturing human epithelial cells. MarA/SoxS/Rob inducers provide new potential agents for controlling O157:H7 interactions with the host and persistence in the environment.