FIG. 1.

The S. enterica serovar Typhi ompS1 5′ upstream regulatory region. The P1 OmpR-dependent promoter, the P2 OmpR-repressed promoter, and the six OmpR-binding boxes (I to VI), as described previously (22), are shown. The number of base pairs upstream of the P1 transcriptional start, as contained in the ompS1-lacZ fusions (22), is indicated throughout the region. The long horizontal bar delimits the region required for silencing and osmoregulation. The d4 bar shows the 31-bp deletion from −135 to −105.