The PmrA-PmrB two-component system responding to acidic pH and iron controls virulence in the plant pathogen Erwinia carotovora ssp. carotovora.

Efficient response to environmental cues is crucial to successful infection by plant-pathogenic bacteria such as Erwinia carotovora ssp. carotovora. The expression of the main virulence genes of this pathogen, encoding extracellular enzymes that degrade the plant-cell wall, is subject to complex regulatory machinery where two-component systems play an important role.