A Dual Regulatory Role of the PhoU Protein in Salmonella Typhimurium
ABSTRACT Bacteria utilize two-component regulatory systems to sense and respond to their surroundings. Unlike other two-component systems that directly sense through a sensory domain in the histidine kinase (HK), the PhoB/PhoR two-component system requires additional proteins, including the PstSCAB...
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| Format: | Article |
| Language: | English |
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American Society for Microbiology
2022-06-01
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| Series: | mBio |
| Subjects: | |
| Online Access: | https://journals.asm.org/doi/10.1128/mbio.00811-22 |
| _version_ | 1811342717524901888 |
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| author | Soomin Choi Gyunghwa Jeong Eunna Choi Eun-Jin Lee |
| author_facet | Soomin Choi Gyunghwa Jeong Eunna Choi Eun-Jin Lee |
| author_sort | Soomin Choi |
| collection | DOAJ |
| description | ABSTRACT Bacteria utilize two-component regulatory systems to sense and respond to their surroundings. Unlike other two-component systems that directly sense through a sensory domain in the histidine kinase (HK), the PhoB/PhoR two-component system requires additional proteins, including the PstSCAB phosphate transporter and the PhoU protein, to sense phosphate levels. Although PhoU is involved in phosphate signaling by connecting the PstSCAB transporter and PhoR histidine kinase, the mechanism by which PhoU controls expression of pho regulon genes has not yet been clearly understood. Here, we identified PhoU residues required for interacting with PhoR histidine kinase from the intracellular pathogen Salmonella enterica serovar Typhimurium. The PhoU Ala147 residue interacts with the PhoR PAS domain and is involved in repressing pho expression in high phosphate. Unexpectedly, the PhoU Arg184 residue interacts with the PhoR histidine kinase domain and is required for activating pho expression in low Mg2+ by increasing PhoR autophosphorylation, revealing its new function. The substitution of the Arg184 to Gly codon decreased Salmonella virulence both in macrophages and in mice, suggesting that PhoU’s role in promoting PhoR autophosphorylation is required during Salmonella infection. IMPORTANCE Bacteria constantly sense and respond to their surroundings through two-component systems. In Gram-negative bacteria, phosphate sensing is mediated by the PhoB/PhoR two-component system with additional components, the PstSCAB phosphate transporter and the PhoU protein. PhoU, a regulatory protein that connects the PstSCAB phosphate transporter to the PhoB/PhoR two-component system, is believed to function as a negative regulator in phosphate signaling because the phoU deletion mutant loses the ability to repress pho expression in high phosphate. Using single amino acid substitutions in the intracellular pathogen Salmonella enterica serovar Typhimurium, PhoU turns out to control PhoR histidine kinase differently, depending on the conditions. The PhoU-PhoR PAS domain interaction is involved in repressing pho expression in high phosphate, whereas the PhoU-PhoR HK domain interaction is involved in activating autophosphorylation of PhoR histidine kinase in low Mg2+ and thus promotes Salmonella virulence. Therefore, PhoU appears to modulate phosphate signaling exquisitely according to external conditions. |
| first_indexed | 2024-04-13T19:15:41Z |
| format | Article |
| id | doaj.art-8c1cb216a6ee4d3899004d6601ec0228 |
| institution | Directory Open Access Journal |
| issn | 2150-7511 |
| language | English |
| last_indexed | 2024-04-13T19:15:41Z |
| publishDate | 2022-06-01 |
| publisher | American Society for Microbiology |
| record_format | Article |
| series | mBio |
| spelling | doaj.art-8c1cb216a6ee4d3899004d6601ec02282022-12-22T02:33:41ZengAmerican Society for MicrobiologymBio2150-75112022-06-0113310.1128/mbio.00811-22A Dual Regulatory Role of the PhoU Protein in Salmonella TyphimuriumSoomin Choi0Gyunghwa Jeong1Eunna Choi2Eun-Jin Lee3Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, South KoreaDepartment of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, South KoreaDepartment of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, South KoreaDepartment of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, South KoreaABSTRACT Bacteria utilize two-component regulatory systems to sense and respond to their surroundings. Unlike other two-component systems that directly sense through a sensory domain in the histidine kinase (HK), the PhoB/PhoR two-component system requires additional proteins, including the PstSCAB phosphate transporter and the PhoU protein, to sense phosphate levels. Although PhoU is involved in phosphate signaling by connecting the PstSCAB transporter and PhoR histidine kinase, the mechanism by which PhoU controls expression of pho regulon genes has not yet been clearly understood. Here, we identified PhoU residues required for interacting with PhoR histidine kinase from the intracellular pathogen Salmonella enterica serovar Typhimurium. The PhoU Ala147 residue interacts with the PhoR PAS domain and is involved in repressing pho expression in high phosphate. Unexpectedly, the PhoU Arg184 residue interacts with the PhoR histidine kinase domain and is required for activating pho expression in low Mg2+ by increasing PhoR autophosphorylation, revealing its new function. The substitution of the Arg184 to Gly codon decreased Salmonella virulence both in macrophages and in mice, suggesting that PhoU’s role in promoting PhoR autophosphorylation is required during Salmonella infection. IMPORTANCE Bacteria constantly sense and respond to their surroundings through two-component systems. In Gram-negative bacteria, phosphate sensing is mediated by the PhoB/PhoR two-component system with additional components, the PstSCAB phosphate transporter and the PhoU protein. PhoU, a regulatory protein that connects the PstSCAB phosphate transporter to the PhoB/PhoR two-component system, is believed to function as a negative regulator in phosphate signaling because the phoU deletion mutant loses the ability to repress pho expression in high phosphate. Using single amino acid substitutions in the intracellular pathogen Salmonella enterica serovar Typhimurium, PhoU turns out to control PhoR histidine kinase differently, depending on the conditions. The PhoU-PhoR PAS domain interaction is involved in repressing pho expression in high phosphate, whereas the PhoU-PhoR HK domain interaction is involved in activating autophosphorylation of PhoR histidine kinase in low Mg2+ and thus promotes Salmonella virulence. Therefore, PhoU appears to modulate phosphate signaling exquisitely according to external conditions.https://journals.asm.org/doi/10.1128/mbio.00811-22phosphate limitationlow Mg2+pst phosphate-transport systemPhoB/PhoR two-component systemphosphate limitation |
| spellingShingle | Soomin Choi Gyunghwa Jeong Eunna Choi Eun-Jin Lee A Dual Regulatory Role of the PhoU Protein in Salmonella Typhimurium mBio phosphate limitation low Mg2+ pst phosphate-transport system PhoB/PhoR two-component system phosphate limitation |
| title | A Dual Regulatory Role of the PhoU Protein in Salmonella Typhimurium |
| title_full | A Dual Regulatory Role of the PhoU Protein in Salmonella Typhimurium |
| title_fullStr | A Dual Regulatory Role of the PhoU Protein in Salmonella Typhimurium |
| title_full_unstemmed | A Dual Regulatory Role of the PhoU Protein in Salmonella Typhimurium |
| title_short | A Dual Regulatory Role of the PhoU Protein in Salmonella Typhimurium |
| title_sort | dual regulatory role of the phou protein in salmonella typhimurium |
| topic | phosphate limitation low Mg2+ pst phosphate-transport system PhoB/PhoR two-component system phosphate limitation |
| url | https://journals.asm.org/doi/10.1128/mbio.00811-22 |
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