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

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

来源：Journal of Biosciences, 2013, 38(3): 499-507.

DOI：10.1007/s12038-013-9347-2

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

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 lip-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 hp, fimZ and fimA.

• 出版日期2013-9
• 单位河北医科大学