Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2005 Apr;60(4):462-74.
doi: 10.1007/s00239-004-0212-7.

Comparison of the PhoPQ Regulon in Escherichia Coli and Salmonella Typhimurium


Comparison of the PhoPQ Regulon in Escherichia Coli and Salmonella Typhimurium

Pieter Monsieurs et al. J Mol Evol. .


The PhoPQ two-component system acts as a transcriptional regulator that responds to Mg(2+) starvation both in Escherichia coli and Salmonella typhimurium (Garcia et al. 1996; Kato et al. 1999). By monitoring the availability of extracellular Mg(2+), this two-component system allows S. typhimurium to sense the transition from an extracellular environment to a subcellular location. Concomitantly with this transition, a set of virulence factors essential for survival in the intracellular environment is activated by the PhoPQ system (Groisman et al. 1989; Miller et al. 1989). Compared to nonpathogenic strains, such as E. coli K12, the PhoPQ regulon in pathogens must contain target genes specifically contributing to the virulence phenotype. To verify this hypothesis, we compared the composition of the PhoPQ regulon between E. coli and S. typhimurium using a combination of expression experiments and motif data. PhoPQ-dependent genes in both organisms were identified from PhoPQ-related microarray experiments. To distinguish between direct and indirect targets, we searched for the presence of the regulatory motif in the promoter region of the identified PhoPQ-dependent genes. This allowed us to reconstruct the direct PhoPQ-dependent regulons in E. coli K12 and S. typhimurium LT2. Comparison of both regulons revealed a very limited overlap of PhoPQ-dependent genes between both organisms. These results suggest that the PhoPQ system has acquired a specialized function during evolution in each of these closely related species that allows adaptation to the specificities of their lifestyles (e.g., pathogenesis in S. typhimurium).

Similar articles

See all similar articles

Cited by 48 articles

See all "Cited by" articles


    1. Annu Rev Microbiol. 2000;54:519-65 - PubMed
    1. Proc Natl Acad Sci U S A. 2003 Apr 15;100(8):4706-11 - PubMed
    1. J Bacteriol. 1996 Dec;178(23):6796-801 - PubMed
    1. Clin Microbiol Rev. 1999 Jul;12(3):405-28 - PubMed
    1. Microbiology. 1999 Feb;145 ( Pt 2):367-78 - PubMed

Publication types

MeSH terms

LinkOut - more resources