The Staphylococcus aureus KdpDE Two-Component System Couples Extracellular K + Sensing and Agr Signaling to Infection Programming

Abstract

ABSTRACT The Kdp system is widely distributed among bacteria. In Escherichia coli , the Kdp-ATPase is a high-affinity K + uptake system and its expression is activated by the KdpDE two-component system in response to K + limitation or salt stress. However, information about the role of this system in many bacteria still remains obscure. Here we demonstrate that KdpFABC in Staphylococcus aureus is not a major K + transporter and that the main function of KdpDE is not associated with K + transport but that instead it regulates transcription for a series of virulence factors through sensing external K + concentrations, indicating that this bacterium might modulate its infectious status through sensing specific external K + stimuli in different environments. Our results further reveal that S. aureus KdpDE is upregulated by the Agr/RNAIII system, which suggests that KdpDE may be an important virulence regulator coordinating the external K + sensing and Agr signaling during pathogenesis in this bacterium.