Table 1.

Genes and cellular activities regulated by PhoP-PhoQ inSalmonella

GeneFunction and /or properties of gene productPresent inE. coli K-12?
hilATranscriptional regulator of invasion genesNo
mgtAP-type ATPase Mg2+transporterYes
mgtBP-type ATPase Mg2+ transporterNo
mgtCMg2+ acquisition; intramacrophage survivalNo
pagCOuter membrane protein with sequence similarity to EnterobacterOmpX, Yersinia Ail, and phage lambda LomNo
pagPOuter membrane enzyme mediating transfer of palmitate to lipid A; resistance to peptide C18GYes
pbgPEoperonSynthesis and/or incorporation of 4-aminoarabinose into lipid A; resistance to polymyxinYes
pcgLPeriplasmic d-Ala-d-Ala dipeptidaseNoa
pgtEOuter membrane protease; resistance to peptide C18GNoa
phoNPeriplasmic nonspecific acid phosphataseNo
phoPQMg2+ -responding two-component systemYes
pmrABFe3+ -responding two-component systemYes
pmrDMediator of transcriptional activation of pmrA-regulated genes during growth in low Mg2+Yes
prgHIJKComponents of Inv-Spa type III secretion systemNo
spvBMono(ADP-ribosyl)transferase encoded in Salmonella virulence plasmidNo
ugdUDP-d-glucose dehydrogenaseYes
ugtLPutative membrane proteinNo
  • a E. coli K-12 harbors two genes,ecovanX and ompT, encoding products that are only 40 and 46% identical to the Salmonella pcgL andpgtE gene products, respectively. However, these genes are not true homologs and, like Salmonella pcgL andpgtE, the E. coli genes appear to have been acquired horizontally.