Disease relevance of phoP

• Both E. coli and S. typhimurium phoP mutants were more sensitive than their isogenic wild-type strains to the frog-derived antibacterial peptide magainin 2, suggesting a role for PhoP in the response to various stresses in both enteric species [1].
• We hypothesized that Salmonella phoP-activated genes, which are transcriptionally activated within antigen-processing macrophages, could prove useful for delivery of heterologous antigens to the immune system [2].
• Strain ATCC14028 releases a lambdoid phage, named Gifsy-3, which contains the phoP/phoQ-activated pagJ gene and the gene for the secreted leucine-rich repeat protein SspH1 [3].

High impact information on phoP

• Mutation of the phoP gene rendered Salmonella as sensitive to hydrogen peroxide as an rpoS mutant after growth in low Mg(2+) [4].
• Remarkably, though all mice had comparable antibody responses to lipopolysaccharide, only mice immunized with strains bearing phoP-activated fusion genes had antibody responses to the heterologous antigen [2].
• Sequences homologous to phoP were found in several Gram-negative species and in the yeast Saccharomyces cerevisiae [5].
• We present here the DNA sequence of the phoP gene and show that the deduced amino acid sequence of phoP has extensive homology with the Escherichia coli transcriptional regulators PhoB and OmpR, which control the expression of loci in response to different environmental stimuli [5].
• The antigens included lipopolysaccharide (LPS) from wild-type and msbB-null Escherichia coli and phoP-null and phoP-constitutive Salmonella enterica serovar Typhimurium strains, as well as LPS, lipid A, and lipoteichoic acid from Pseudomonas aeruginosa and Listeria monocytogenes grown in Mg2+-limited media [6].

Biological context of phoP

• Analysis of a phoP-lacZ promoter fusion showed that the phoPR operon is hyperinduced in a spo0A mutant strain, suggesting that Spo0A approximately P represses APases by repressing phoPR transcription [7].
• Molecular genetic analysis of the Escherichia coli phoP locus [1].
• The phoP gene was mapped to kilobase 1202 on the Kohara map (25-min region) of the E. coli genome (Y. Kohara, K. Akiyama, and K. Isono, Cell 50:495-508, 1987) and found to be transcribed in a counterclockwise direction [1].
• The phoP-phoQ operon was mapped at 25 min on the standard E. coli linkage map by hybridization with the Kohara mini set library of the E. coli chromosome (Y. Kohara, K. Akiyama, and K. Isono, Cell 50:495-508, 1987) [8].

Anatomical context of phoP

• Macrophages also processed phoP S. typhimurium strains with greater efficiency for peptide presentation by I-Ak than wild type bacteria while Salmonella constitutively expressing phoP were processed for peptide presentation by I-Ak less efficiently than wild type Salmonella [9].

Other interactions of phoP

• The mRNA levels of W3110 in the presence of 30 mM MgCl(2), WP3022 (phoP defective), and WQ3007 (phoQ defective) were compared with those of W3110 in the absence of MgCl(2) [10].

References