Activated by different signals, the PhoP/PhoQ two-component system differentially regulates metal uptake.
The PhoP/PhoQ two-component system controls several physiological and virulence functions in Salmonella enterica. This system is activated by low Mg(2+), acidic pH, and antimicrobial peptides, but the biological consequences resulting from sensing multiple signals are presently unclear. Here, we report that the PhoP/PhoQ system regulates different Salmonella genes depending on whether the inducing signal is acidic pH or low Mg(2+). When Salmonella experiences acidic pH, the PhoP/PhoQ system promotes Fe(2+) uptake in a process that requires the response regulator RstA, activating transcription of the Fe(2+) transporter gene feoB. In contrast, the PhoP-induced RstA protein did not promote feoB expression at neutral pH with low Mg(2+). The PhoP/PhoQ system promotes the expression of the Mg(2+) transporter mgtA gene only when activated in bacteria starved for Mg(2+). This is because mgtA transcription promoted at high Mg(2+) concentrations by the acidic-pH-activated PhoP protein failed to reach the mgtA coding region due to the mgtA leader region functioning as a Mg(2+) sensor. Our results show that a single two-component regulatory system can regulate distinct sets of genes in response to different input signals.
Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Jangan-gu, Suwon, South Korea.
Eunna
E
Choi
Eduardo A
EA
Groisman
Dongwoo
D
Shin
D000251:Adenosine Triphosphatases / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000235:genetics; D015153:Blotting, Western; D027682:Cation Transport Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000378:metabolism; D008670:Metals / Q000378:metabolism*; D010766:Phosphorylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D026901:Membrane Transport Proteins; D008670:Metals; C079792:PhoQ protein, Bacteria; C061064:PhoP protein, Bacteria; D000251:Adenosine Triphosphatases; C093585:MgtA protein, bacteria; C083836:MgtB protein, Salmonella typhimurium; D008274:Magnesium