Control of the phoBR Regulon in Escherichia coli

Abstract

Phosphorus is required for many biological molecules and essential functions, including DNA replication, transcription of RNA, protein translation, posttranslational modifications, and numerous facets of metabolism. In order to maintain the proper level of phosphate for these processes, many bacteria adapt to changes in environmental phosphate levels. The mechanisms for sensing phosphate levels and adapting to changes have been extensively studied for multiple organisms. The phosphate response of Escherichia coli alters the expression of numerous genes, many of which are involved in the acquisition and scavenging of phosphate more efficiently. This review shares findings on the mechanisms by which E. coli cells sense and respond to changes in environmental inorganic phosphate concentrations by reviewing the genes and proteins that regulate this response. The PhoR/PhoB two-component signal transduction system is central to this process and works in association with the high-affinity phosphate transporter encoded by the pstSCAB genes and the PhoU protein. Multiple models to explain how this process is regulated are discussed.

Single cell analyses reveal phosphate availability as critical factor for nutrition ofSalmonella entericawithin mammalian host cells

“…This situation induces the Pst transport system, despite sufficient P i availability in the extracellular space. This model also supports the function of PhoR as sensor for P i in the bacterial cytosol, in line with the absence of the periplasmic domain in PhoR for sensing P i in periplasm and thus extracellular milieu (Gardner & McCleary, 2019).…”

Antibiotic susceptibility signatures identify potential antimicrobial targets in the Acinetobacter baumannii cell envelope

“…A similar pattern was seen with genes associated with phosphate homeostasis. In many bacteria, the two-component system PhoBR transcriptionally regulates phosphate-acquisition in response to signals from the phosphatesensing PstSCAB-PhoU complex 45 . Mutations in one system result in opposite effects on gene expression in the other in E. coli 45 .…”

“…In many bacteria, the two-component system PhoBR transcriptionally regulates phosphate-acquisition in response to signals from the phosphatesensing PstSCAB-PhoU complex 45 . Mutations in one system result in opposite effects on gene expression in the other in E. coli 45 . The phenotypic signatures of the transposon mutations in A. baumannii significantly correlated within each system (phoBR, r = 0.91, p < 10 −11 ; pstSCAB-phoU, r = 0.4-0.81, p < 0.024) while between the two systems they anticorrelated (r = −0.42 to −0.62, p < 0.017) ( Fig.…”

A bacterial tragedy of the commons that masks the actual frequency of mutants

“…Pst is encoded by pstSCAB-phoU operon, or in short pst operon. When Pi concentration declines below 4 μM, PhoR auto-phosphorylates and immediately transfers its Pi moiety to PhoB, which in turn binds to the PHO-box sequences in the promoter regions of all PHO genes thereby initiating the transcription of the PHO regulon genes [24]. Mutations in any one of the five pst operon genes result in the constitutive expression of the PHO regulon.…”

“…Thus, under high-Pi conditions the repressed level of AP activity in the periplasm is too low to provide sufficient glycerol for cell growth. Only PHO-constitutive mutants (PCMs), which carry a null mutation in one of the five pst operon genes [24] express high levels of AP that enable them to grow on G2P medium [26, 32]. Some mutations in phoR also result in the constitutive expression of the PHO regulon and likewise confer on the ability to grow on G2P.…”