Salmonellae utilize the PhoPQ two-component system to sense and survive within the host intracellular environment. The PhoQ histidine kinase has a periplasmic sensor domain which is regulated by divalent cations and activated by acidic pH and cationic antimicrobial peptides (CAMP). Using a combination of structural, biochemical, and in vivo methods we are characterizing distinct subdomain networks within the PhoQ periplasmic domain which are involved in signal transduction. Ultimately, our efforts will provide a structural model of the PhoQ activation mechanism.
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