The Salmonellae PhoQ sensor: mechanisms of detection of phagosome signals.

Sensor histidine kinases are widely used by prokaryotes to regulate gene expression in response to environmental signals, and such sensing is essential for virulence for plants and animals. PhoQ is one such sensor kinase that is conserved across a variety of Gram-negative pathogens and functions as part of a two-component system with its transcriptional regulator PhoP. Salmonella typhimurium PhoPQ is one of the most studied two-component systems and has been demonstrated to regulate hundreds of genes encoding the majority of virulence properties including intracellular survival, invasion, lipid A structure, resistance to antimicrobial peptides, and phagosome alteration.