The transcriptional regulator SsrB is involved in a molecular switch controlling virulence lifestyles of Salmonella
Fig 10
SsrB is involved in a molecular regulatory switch that aids in Salmonella transition to an intracellular lifestyle.
(A) HilD directly or indirectly activates the expression of the SPI-1 genes and several other genes located outside SPI-1, including the flagellar regulatory operon flhDC required for the invasion of host cells. (B) Following its uptake into macrophages, Salmonella resides inside vacuoles, where SsrB induces the expression of the SPI-2 genes and other genes located outside SPI-2, which are required for survival and replication, while simultaneously repressing the expression of the hilD and hilA SPI-1 regulatory genes, and the flagellar-based motility genes. Green arrows and red blunt-end lines indicate positive and negative control, respectively, whereas gray dashed arrows denote expression of the respective genes.