The KdpD/KdpE two-component system of Photorhabdus asymbiotica promotes bacterial survival within M. sexta hemocytes

► Potassium ion concentrations are crucial for the normal process of phagocytic killing of bacteria in hemocytes. ► Provision of the kdpDE two-component potassium sensor from the facultative intracellular pathogen Photorhabdus asymbiotica is sufficient to transform a harmless laboratory strain of E. coli into a lethal intracellular pathogen. ► Resistance to phagocytic killing can be mediated by the action of the Kdp high affinity potassium transporter alone.