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. Author manuscript; available in PMC: 2021 Jan 8.
Published in final edited form as: Calcif Tissue Int. 2019 Nov 25;108(1):16–31. doi: 10.1007/s00223-019-00636-8

Fig. 2.

Fig. 2.

Phosphate sensing in Escherichia coli. The Pi specific transporter (Pst) in periplasmic membrane consists of 4 subunits: PstS, PstA, PstB, and PstC, and functions as a Pi sensor. Under conditions of Pi saturation, PhoU inhibits PhoR activity, leading to increased levels of unphosphorylated PhoB and inactivation of Pho regulon genes. Under conditions of Pi depletion, PhoR is activated by autophosphorylation which in turn phosphorylates PhoB. The phosphorylated PhoB acts as a transcription factor binding to the PHO box of Pho regulon and regulating the transcription of target genes involved in Pi conservation.