Differential Modulation of Flagella Expression in Enterohemorrhagic Escherichia coli O157:H7 by Intestinal Short Chain Fatty Acid Mixes.

Differential Modulation of Flagella Expression in Enterohemorrhagic Escherichia coli O157:H7 by Intestinal Short Chain Fatty Acid Mixes.

Microbiology. 2016 Aug 16;

Authors: Lackraj T, Kim JI, Tran SL, Barnett Foster D

Abstract
During passage through the gastrointestinal tract, enterohemorrhagic Escherichia coli (EHEC) encounters numerous stresses, each producing unique antimicrobial conditions. Beyond surviving these stresses, EHEC may also use them as cues about the local microenvironment to modulate its virulence. Of particular interest is how exposure to changing concentrations of short chain fatty acids (SCFA) associated with passage through the small and large intestines affects EHEC virulence, and specifically flagella expression and motility. In this study, we investigate the impact of exposure to SCFA mixes simulating concentrations and compositions within the small and large intestine on EHEC flagella expression and function. Using a combination of DNA microarray, qRT PCR, immunoblot, flow cytometry, and motility assays, we show that when EHEC is exposed to SCFA mixes representative of the small intestine, there is a marked, significant upregulation of flagellar genes, flagellar protein FliC and motility. By contrast, when EHEC is exposed to SCFA mixes representative of the large intestine, there is a significant downregulation of flagellar genes, FliC and motility. Our results demonstrate that EHEC modulates flagella expression and motility in response to SCFAs, with differential responses associated with SCFA mixes typical of the small and large intestines. This research contributes to our understanding of how EHEC senses and responds to host environmental signals and the mechanisms it uses to successfully infect the human host. Significantly, it also suggests that EHEC is using this key gastrointestinal chemical signpost to cue changes in flagella expression and motility in different locations within the host intestinal tract.

PMID: 27535670 [PubMed - as supplied by publisher]

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