FIGURE 2.

S. Tm senses environmental cues to adapt to the intramacrophage environment. (A) S. Tm recognizes diverse signals within the macrophage. These include iron limitation, ethanolamine, acidic pH, antimicrobial peptides, divalent cations, epinephrine/norepinephrine, and cellular ATP. These signals act to induce SPI-2 expression and establish the SCV as a replicative niche. (B) Schematic of some of the regulatory proteins and associated signals important for activating SPI-2 expression. Signals are written blue; regulatory proteins and TCS are written in red. TLRs, Toll-like receptors; SCV, Salmonella containing vacuole.