Expression of the rfa, LPS biosynthesis promoter in Salmonella typhimurium during invasion of intestinal epithelial cells

John J. Maurer, Teresa A. Doggett, Lisa Burns-Keliher, Roy Curtiss

Research output: Contribution to journalArticle

5 Scopus citations


Salmonella regulates transcription of many of its genes in response to environmental conditions encountered inside or outside the eukaryotic cells it infects. In this paper, we examined Salmonella typhimurium gene expression within epithelial cells, by using bacterial luciferase as a reporter. We focused on gene expression controlled by Salmonella rfa promoter, using lac promoter as a control. We observed down regulation for both promoters during the initial 2 h of invasion. The decreased levels of luciferase activity appeared to be due to metabolic changes, since we observed similar results with tissue culture medium alone. Gene expression stabilized to a new steady state for the Salmonella rfa promoter, while a lac promoter activity steadily decreased. Bacterial luciferase activity was a good indicator of intracellular numbers and allowed us to detect as few as 1000 bacterial cells/infected monolayer. Both promoters were not dependent on host protein synthesis for expression.

Original languageEnglish (US)
Pages (from-to)172-176
Number of pages5
JournalCurrent Microbiology
Issue number3
StatePublished - Jan 1 2000


ASJC Scopus subject areas

  • Microbiology
  • Applied Microbiology and Biotechnology

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