Salmonellae PhoPQ regulation of the outer membrane to resist innate immunity

Curr Opin Microbiol. 2014 Feb;17:106-13. doi: 10.1016/j.mib.2013.12.005. Epub 2014 Feb 14.


Salmonellae sense host cues to regulate properties important for bacterial survival and replication within host tissues. The PhoPQ two-component regulatory system senses phagosome acidification and cationic antimicrobial peptides (CAMP) to regulate the protein and lipid contents of the bacterial envelope that comprises an inner and outer membrane. PhoPQ-regulated lipid components of the outer membrane include lipopolysaccharides and glycerophospholipids. Envelope proteins regulated by PhoPQ, include: components of virulence associated secretion systems, the flagellar apparatus, membrane transport systems, and proteins that are likely structural components of the outer membrane. PhoPQ alteration of the bacterial surface results in increased bacterial resistance to CAMP and decreased detection by the innate immune system. This review details the molecular complexity of the bacterial cell envelope and highlights the outer membrane lipid bilayer as an environmentally regulated bacterial organelle.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Animals
  • Antimicrobial Cationic Peptides
  • Bacterial Proteins*
  • Cell Membrane* / chemistry
  • Cell Membrane* / metabolism
  • Humans
  • Immunity, Innate*
  • Mice
  • Salmonella* / immunology
  • Salmonella* / pathogenicity
  • Salmonella* / physiology
  • Virulence


  • Antimicrobial Cationic Peptides
  • Bacterial Proteins
  • PhoQ protein, Bacteria
  • PhoP protein, Bacteria