Fig. 3.

Architectures of PhoP-activated promoters in Salmonella and Yersinia. (A and B) Sequences of the promoter regions of the transcripts directly activated by PhoP in Salmonella (A) and Yersinia (B). The transcription start sites are indicated in blue, the PhoP boxes are in red, and the putative −10 sequences are underlined. Boxes and arrows indicate the location and orientation of the PhoP binding sites across promoters. The Salmonella PhoP-activated transcripts have been described previously (23, 26). The Yersinia PhoP-dependent transcripts were uncovered as described in Materials and Methods (Fig. S4). PhoP binding to all promoters was determined in vivo by ChIP-chip and/or ChIP-real-time PCR and in several cases in vitro by DNase I footprinting (Fig. S4). (C) Summary of the distribution of promoter architectures and the differential ability of the Salmonella and Yersinia PhoP proteins to activate transcription. Although the mgtA-like promoter architecture is shared by several Salmonella and Yersinia PhoP-activated genes, other members of the regulon harbor promoter structures that are absent from the other organism. The Salmonella and Yersinia PhoP proteins differ in their ability to activate expression from genes of the latter group.