Ordered expression of virulence genes inSalmonella enterica serovar typhimurium

摘要

Using transcriptional promoter fusions, we investigated the expression of selected SPI-1 and SPI-2 genes ofSalmonella enterica serovar Typhimurium (S. Typhimurium). Promoters of genes related to the invasion of the epithelial cell (hilA, hilC, hilD, invF, sicA, sopA, sopB andsopE2) were active in Luria-Bertani (LB) medium and LB with butyrate but were suppressed by bile salts and in glucose minimal (M9) medium. Genes related toS. Typhimurium intracellular survival (phoP, ssrA, ssaB, ssaG, sifA, sifB andpipB) were characterized by their expression in stationary phase in LB and M9 medium. Activity ofphoP andssrA promoters indicated that these might be expressed inside the gut. SPI-1 genes were expressed on the transition to stationary phase while SPI-2 genes were expressed in stationary phase. Among SPI-1 genes, those with regulatory functions preceded in expression the effector genes andsop genes were expressed in the order ofsopA, sopB andsopE2, showing hierarchy in the expression ofS. Typhimurium virulence genes.