caa a22 4500 475746643 CHVBK 20180406123515.0 cr unu---uuuuu 170329e20000901xx s 000 0 eng 10.1007/s002840010113 doi (NATIONALLICENCE)springer-10.1007/s002840010113 Expression of the rfa , LPS Biosynthesis Promoter in Salmonella typhimurium During Invasion of Intestinal Epithelial Cells [Elektronische Daten] [John J. Maurer, Teresa A. Doggett, Lisa Burns-Keliher, Roy Curtiss III] 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. Springer-Verlag New York Inc., 2000 Maurer John J. Department of Biology, Washington University, St. Louis, MO 63130, USA, US aut Doggett Teresa A. Department of Biology, Washington University, St. Louis, MO 63130, USA, US aut Burns-Keliher Lisa Department of Biology, Washington University, St. Louis, MO 63130, USA, US aut Curtiss III Roy Department of Biology, Washington University, St. Louis, MO 63130, USA, US aut https://doi.org/10.1007/s002840010113 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s002840010113 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Maurer John J. Department of Biology, Washington University, St. Louis, MO 63130, USA, US aut NATIONALLICENCE 700 1- Doggett Teresa A. Department of Biology, Washington University, St. Louis, MO 63130, USA, US aut NATIONALLICENCE 700 1- Burns-Keliher Lisa Department of Biology, Washington University, St. Louis, MO 63130, USA, US aut NATIONALLICENCE 700 1- Curtiss III Roy Department of Biology, Washington University, St. Louis, MO 63130, USA, US aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer