Recombinant Salmonella typhimurium Virulence sensor histidine kinase PhoQ (phoQ), partial

Function

Member of the two-component regulatory system PhoP/PhoQ which regulates the expression of genes involved in virulence, adaptation to acidic and low Mg(2+) environments and resistance to host defense antimicrobial peptides (PubMed:2544889, PubMed:9573193). Essential for intramacrophage survival of S.typhimurium (PubMed:2544889). Also involved in adaptation to hyperosmotic environments, in a Mg(2+)-independent manner (By similarity). In low periplasmic Mg(2+), PhoQ functions as a membrane-associated protein kinase that undergoes autophosphorylation and subsequently transfers the phosphate to PhoP, resulting in the expression of PhoP-activated genes (PAG) and repression of PhoP-repressed genes (PRG) (PubMed:10807931, PubMed:11160113, PubMed:12618457, PubMed:15910283). In high periplasmic Mg(2+), acts as a protein phosphatase that dephosphorylates phospho-PhoP, resulting in the repression of PAG and may lead to expression of some PRG (PubMed:10807931, PubMed:11160113, PubMed:12618457, PubMed:15910283). Essential for transcription of spiC inside macrophages by controlling the expression of the two-component regulatory system SsrB/SpiR (SsrA) and Pir at transcriptional and post-transcriptional levels respectively (PubMed:19229334). Promotes expression of the two-component regulatory system PmrA/PmrB via activation of pmrD gene (PubMed:32413287). Is required to attenuate bacterial growth within fibroblast cells and to enhance bacterial resistance to bile in intestinal cells. Negatively regulates prgH, which is required for invasion of epithelial cells. Involved in acid tolerance (PubMed:9573193)

Subcellular Location

Cell inner membrane (Multi-pass membrane protein)

Subunit

Homodimer (Probable); probably dimerizes via the cytoplasmic domain. Interacts with MgrB in the periplasm, altering its activity and that of downstream effector PhoP (By similarity)

• Miller S.I. et al. A two-component regulatory system (phoP phoQ) controls Salmonella typhimurium virulence. — Proc. Natl. Acad. Sci. U.S.A. (1989)
• McClelland M. et al. Complete genome sequence of Salmonella enterica serovar Typhimurium LT2. — Nature (2001)
• Bearson B.L. et al. A low pH-inducible, PhoPQ-dependent acid tolerance response protects Salmonella typhimurium against inorganic acid stress. — J. Bacteriol. (1998)
• Castelli M.E. et al. The phosphatase activity is the target for Mg2+ regulation of the sensor protein PhoQ in Salmonella. — J. Biol. Chem. (2000)
• Montagne M. et al. Characterization of the catalytic activities of the PhoQ histidine protein kinase of Salmonella enterica serovar Typhimurium. — J. Bacteriol. (2001)
• Sanowar S. et al. Mutational analysis of the residue at position 48 in the Salmonella enterica Serovar Typhimurium PhoQ sensor kinase. — J. Bacteriol. (2003)
• Sanowar S. et al. Functional reconstitution of the Salmonella typhimurium PhoQ histidine kinase sensor in proteoliposomes. — Biochem. J. (2005)
• Yoon H. et al. Coordinated regulation of virulence during systemic infection of Salmonella enterica serovar Typhimurium. — PLoS Pathog. (2009)