Proteolytic feedback of quorum sensing promotes infection by Pseudomonas aeruginosa

RhlR abundance in Pseudomonas aeruginosa is actively tuned by ATP-dependent proteolysis via a self-limiting negative feedback loop, shaping QS timing and virulence.

• Why it matters: QS circuits must be reset or attenuated, but how receptor levels are controlled to limit high-density programs is unclear.
• What they did: The study mapped an N-terminal degron in RhlR protected by PqsE, required for degradation by Lon and the ClpP1–ClpP2 complex, and tested degron removal and RhlR DNA-binding disruption.
• The result: Stabilizing RhlR advanced QS-regulated gene expression, enhanced biofilm formation, imposed an in vitro fitness cost, and reduced virulence in an acute mouse lung infection.

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