A low-pH medium in vitro or the environment within a macrophage decreases the transcriptional levels of fimA, fimZ and lrp in Salmonella enterica serovar Typhimurium

Ke Chuan Wang, Yuan Hsun Hsu, Yi Ning Huang, Ter Hsin Chen, Jiunn Horng Lin, Shih Ling Hsuan, Maw Sheng Chien, Wei Cheng Lee, Kuang Sheng Yeh

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Many Salmonella Typhimurium isolates produce type 1 fimbriae and exhibit fimbrial phase variation in vitro. Static broth culture favours the production of fimbriae, while solid agar medium inhibits the generation of these appendages. Little information is available regarding whether S. Typhimurium continues to produce type 1 fimbriae during in vivo growth. We used a type 1 fimbrial phase-variable strain S. Typhimurium LB5010 and its derivatives to infect RAW 264.7 macrophages. Following entry into macrophages, S. Typhimurium LB5010 gradually decreased the transcript levels of fimbrial subunit gene fimA, positive regulatory gene fimZ, and global regulatory gene lrp. A similar decrease in transcript levels was detected by RT-PCR when the pH of static broth medium was shifted from pH 7 to a more acidic pH 4. A fimA-deleted strain continued to multiply within macrophages as did the parental strain. An lrp deletion strain was unimpaired for in vitro growth at pH 7 or pH 4, while a strain harboring an lrp-containing plasmid exhibited impaired in vitro growth at pH 4. We propose that acidic medium, which resembles one aspect of the intracellular environment in a macrophage, inhibits type 1 fimbrial production by down-regulation of the expression of lrp, fimZ and fimA.

Original languageEnglish
Pages (from-to)499-507
Number of pages9
JournalJournal of Biosciences
Volume38
Issue number3
DOIs
Publication statusPublished - Sep 2013

Keywords

  • fimA
  • fimZ
  • low pH
  • lrp
  • macrophage
  • Salmonella enterica serovar Typhimurium

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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