RetS senses neurotransmitter norepinephrine and adrenergic agents to regulate Pseudomonas aeruginosa virulence

Abstract

Bacterial cells employ diverse mechanisms to perceive and respond to host-associated molecules, coordinate intracellular signal transduction, and engage in interkingdom communications. In this study, we firstly discovered that the adrenergic antagonist dronedarone (DDR) effectively suppresses quorum sensing (QS) and pathogenesis of the opportunistic pathogen P. aeruginosa. Further analysis revealed that DDR targets RetS, an bacterial surface receptor critical for suppressing the GacS/GacA two-component regulatory system (TCS). Interestingly, the adrenergic agonist norepinephrine (NE) was found to exert opposite effects against RetS, thereby reversing DDR-induced phenotypes in P. aeruginosa. Moreover, we identified the hinge region of RetSDISMED2 serves as a binding pocket of NE and DDR, which provides potential mechanisms of the antagonistic effect of NE and DDR. Our study demonstrated that NE promotes P. aeruginosa infections while DDR can serve as an anti-virulence compound against P. aeruginosa infections. Thus, RetS might serve as a bacterial adrenergic receptor which keeps the NE under constant surveillance. SignificanceSensing and recognition of host-derived molecules, as well as therapeutic drugs, are crucial for the survival of pathogens during infection process. The adrenergic drugs are well known to affect virulence and pathogenesis of the opportunistic pathogen Pseudomonas aeruginosa (P. aeruginosa). In this work, we have provided in-depth characterization of a Norepinephrine (NE) receptor in P. aeruginosa, the RetS membrane protein. NE is the-adrenergic agonist known as a stress hormone, exerts its activity through interaction with mammalian adrenergic receptors (AR). It has been shown that increased NE concentration during early sepsis can stimulate the growth of various Gram-negative and Gram-positive bacteria, including P. aeruginosa. We revealed that both adrenergic agonist NE and another adrenergic antagonist dronedarone (DDR) are able to interfering the RetS-GacS/GacA signaling cascade of P. aeruginosa and execute opposite impact on the pathogenesis of P. aeruginosa during infections.