The Salmonella typhimurium Flagellar Basal Body Protein FliE Is Required for Flagellin Production and to Induce a Proinflammatory Response in Epithelial Cells

• Published in: The Journal of biological chemistry Vol. 277; no. 15; pp. 13346 - 13353
• Main Authors: Reed, Katharine A., Hobert, Michael E., Kolenda, Claire E., Sands, Kara A., Rathman, Michelle, O'Connor, Miriam, Lyons, Sean, Gewirtz, Andrew T., Sansonetti, Philippe J., Madara, James L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.04.2002; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Bacterial Adhesion; Bacterial Proteins - genetics; Bacterial Proteins - physiology; Base Sequence; Cell Line; DNA Primers; Dogs; Down-Regulation; Enzyme-Linked Immunosorbent Assay; Escherichia coli Proteins; Flagellin - biosynthesis; fliE gene; FliE protein; Genetic Complementation Test; Humans; I^KB^a protein; IBa protein; Interleukin-8 - metabolism; Intestinal Mucosa - microbiology; Microscopy, Electron; Salmonella typhimurium; Salmonella typhimurium - metabolism; Salmonella typhimurium - physiology; TLR5 protein
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M200149200

During apical colonization by Salmonella typhimurium, intestinal epithelial cells orchestrate a proinflammatory response that involves secretion of chemoattractants, predominantly interleukin-8, which coordinate neutrophil trans-epithelial migration at the site of infection. This host-pathogen interaction requires several S. typhimurium genes. To identify novel genes that participate in this pathogen-induced proinflammatory response, we created S. typhimurium Tn-10 transposon mutants and identified a single mutant with Tn-10 insertional inactivation within the fliE flagellar locus that was able to adhere to and invade intestinal epithelial cells normally but was unable to induce interleukin-8 secretion in host cells. The fliE-deficient mutant failed to secrete flagellin and lacked any surface assembly of flagellae. Unlike wild-type S. typhimurium, the fliE-deficient mutant did not activate the IκBα/NF-κB signaling pathway or induce the coordinated trans-epithelial migration of isolated human neutrophils. Transcomplementation of the fliE-deficient mutant with a wild-type fliE-harboring plasmid restored all defects and produced a wild-type S. typhimurium phenotype. Furthermore, functional down-regulation of basolateral TLR5 completely inhibited the monolayers' ability to respond to both wild-type S. typhimurium and purified flagellin but had no affect on tumor necrosis factor α-induced responses. We therefore conclude that S. typhimurium fliE is essential for flagellin secretion, flagellar assembly, and S. typhimurium-induced proinflammatory responses through basolateral TLR5 and is consistent with the emerging model of S. typhimurium flagellin-induced inflammation.