EcoSal Plus
Domain 5:
Responding to the Environment
Control of the phoBR Regulon in Escherichia coli
- Authors: Stewart G. Gardner1, and William R. McCleary2
- Editor: James M. Slauch3
-
VIEW AFFILIATIONS HIDE AFFILIATIONSAffiliations: 1: Department of Biological Sciences, Emporia State University, Emporia, KS 66801; 2: Microbiology and Molecular Biology Department, Brigham Young University, Provo, UT 84602; 3: The School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, IL
-
Received 07 February 2019 Accepted 02 July 2019 Published 12 September 2019
- Address correspondence to William R. McCleary, [email protected]

-
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.
-
Citation: Gardner S, McCleary W. 2019. Control of the phoBR Regulon in Escherichia coli, EcoSal Plus 2019; doi:10.1128/ecosalplus.ESP-0006-2019




Control of the phoBR Regulon in Escherichia coli, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/ecosalplus/8/2/ESP-0006-2019-1.gif /docserver/preview/fulltext/ecosalplus/8/2/ESP-0006-2019-2.gif

References

Article metrics loading...
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.

Full text loading...

Figures

Click to view
Figure 1
Predicted domain structure of PhoR. PhoR, like other SHKs, is a dimer that is composed of multiple domains. It autophosphorylates on His-213. TM, transmembrane domain; CR, charged region; PAS domain; DHp, dimerization and histidine phosphorylation domain; CA, catalytic and ATP-binding domain.

Click to view
Figure 2
Transport cycle of PstSCAB transporter. The PstS protein is the periplasmic phosphate-binding protein that binds and presents Pi to the transmembrane components PstC and PstA. PstB binds ATP, which stabilizes a closed nucleotide-binding domain with PstC and PstA adopting an outward-facing conformation. Pi-loaded PstS triggers ATP hydrolysis, which causes a conformational change between the PstB protomers that switch the PstC/PstA proteins into an inward-facing structure. ATP binding resets the system to the outward-facing structure.

Click to view
Figure 3
Model for transmembrane signal transduction to regulate the Pho regulon in E. coli. The output of this signal transduction system is based upon the amount and phosphorylation state of the response regulator PhoB. Phospho-PhoB forms a dimer and binds to DNA sequences containing a Pho box. The phosphorylation state of PhoB is, in turn, controlled by the opposing autokinase/phosphotransferase and phosphatase activities of PhoR, the SHK of the system. The activities of PhoR are ultimately controlled by the PstSCAB transporter and PhoU. When environmental Pi levels are high, the transporter signals through PhoU to favor PhoR in its phosphatase conformation. When environmental Pi levels are low, the transporter and PhoU signal PhoR to favor its autokinase conformation. In an alternate (or supplementary) mechanism, the PstSCAB transporter may also signal Pi sufficiency to PhoR through a process in which its conformation is sensitive to intracellular Pi levels by binding Pi at a low-affinity, cytoplasm-accessible site.
Tables

Click to view
Table 1
Members of the Pho regulon in E. coli K-12 MG1655 identified by RNA-seq
Supplemental Material
No supplementary material available for this content.