The Salmonella typhimurium flagellar basal body protein FliE is required for flagellin production and to induce a proinflammatory response in epithelial cells.
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 IkappaBalpha/NF-kappaB 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 alpha-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.
Reed
Katharine A
KA
Department of Pathology and Laboratory Medicine, Emory University, 615 Michael Street, Whitehead Research Building, Atlanta, GA 30322, USA.
Hobert
Michael E
ME
Kolenda
Claire E
CE
Sands
Kara A
KA
Rathman
Michelle
M
O'Connor
Miriam
M
Lyons
Sean
S
Gewirtz
Andrew T
AT
Sansonetti
Philippe J
PJ
Madara
James L
JL
D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D004285:Dogs; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D029968:Escherichia coli Proteins; D005408:Flagellin / Q000096:biosynthesis*; D005816:Genetic Complementation Test; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000382:microbiology*; D008854:Microscopy, Electron; D012486:Salmonella typhimurium / Q000378:metabolism* / Q000502:physiology
D001426:Bacterial Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D016209:Interleukin-8; D005408:Flagellin; C073764:fliE protein, E coli