FIG. 1.

Phosphate boxes and signal transduction pathway from PhoR to PhoP. (A) PhoR and PhoP consist of the following two domains: C, the carboxyl-terminal domain, and N, the amino-terminal domain. The circled P corresponds to a phosphate group. Each pho box is formed by two elements arranged in a direct repeat separated by three to seven nucleotides. Some promoters contain one pho box, whereas others contain more than one. Two pho boxes are shown in this figure. This model is based on the information available for B. subtilis (24), S. coelicolor, and S. lividans (43). (B) Nucleotide sequences of the pho boxes of E. coli and B. subtilis.