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Sulfane Sulfur Regulates LasR-Mediated Quorum Sensing and Virulence in Pseudomonas aeruginosa PAO1.

ABSTRACT: Sulfane sulfur, such as inorganic and organic polysulfide (HS_n^- and RS_n^-, n > 2), is a common cellular component, produced either from hydrogen sulfide oxidation or cysteine metabolism. In Pseudomonas aeruginosa PAO1, LasR is a quorum sensing master regulator. After binding its autoinducer, LasR binds to its target DNA to activate the transcription of a suite of genes, including virulence factors. Herein, we report that the production of hydrogen sulfide and sulfane sulfur were positively correlated in P. aeruginosa PAO1, and sulfane sulfur was able to modify LasR, which generated Cys¹⁸⁸ persulfide and trisulfide and produced a pentasulfur link between Cys²⁰¹ and Cys²⁰³. The modifications did not affect LasR binding to its target DNA site, but made it several-fold more effective than unmodified LasR in activating transcription in both in vitro and in vivo assays. On the contrary, H₂O₂ inactivates LasR via producing a disulfide bond between Cys²⁰¹ and Cys²⁰³. P. aeruginosa PAO1 had a high cellular sulfane sulfur and high LasR activity in the mid log phase and early stationary phase, but a low sulfane sulfur and low LasR activity in the declination phase. Thus, sulfane sulfur is a new signaling factor in the bacterium, adding another level of control over LasR-mediated quorum sensing and turning down the activity in old cells.

SUBMITTER: Xuan G

PROVIDER: S-EPMC8469610 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Among various environmental stresses, the depletion of inorganic phosphate, which is an important signaling molecule that modulates virulence production, is notable. In our previous study, we demonstrated that lapA, encoding alkaline phosphatase, plays a key role in Pseudomonas aeruginosa biofilm formation in porcine skin explants, an ex vivo chronic wound model. However, the mechanism by which lapA participates in the virulence and biofilm formation of P. aeruginosa remains unclear. In the present study, the lapA deletion mutant was constructed in P. aeruginosa PAO1, and the phenotypic characterization was assessed. Our data demonstrated that phosphate depletion stress significantly enhanced elastase activity, hemolysis, rhamnolipid production, swarming and swimming motilities, and 3-oxo-C12-homoserine lactone (HSL) production in P. aeruginosa. Moreover, phosphate starvation evidently induced the virulence of P. aeruginosa in Caenorhabditis elegans (C. elegans) through fast-kill and slow-kill infections. Deletion of the lapA gene led to broad phenotypic changes, including reduced elastase activity, swimming motility, C4-HSL, and 3-oxo-C12-HSL production, as well as increased chitinase activity and rhamnolipid production under phosphate depletion stress, which was unrelated to C4-HSL. Deletion of the lapA gene also significantly inhibited PAO1 biofilm formation in porcine skin explants by reducing the expression levels of las and rhl quorum sensing systems and extracellular polymeric substance synthesis. Finally, lapA deletion also reduced the virulence of PAO1 in C. elegans in fast-kill and slow-kill infection assays. Thus, the findings suggest that targeting lapA can help control biofilm formation and reduce virulence in nonhealing-infected wounds, where P. aeruginosa is a persistent problem. IMPORTANCE Our previous study demonstrated that the expression of lapA was induced under phosphate depletion conditions, but its roles in virulence and biofilm formation by Pseudomonas aeruginosa remain largely unknown. This study presents a systematic investigation of the roles of lapA in virulence induction and biofilm formation by constructing a lapA-deficient strain with P. aeruginosa PAO1. The results showed that deletion of the lapA gene evidently reduced elastase activity, swimming motility, C4-HSL, and 3-oxo-C12-HSL production, and increased rhamnolipid production under phosphate depletion stress. Moreover, lapA gene deletion inhibited PAO1 biofilm formation in porcine skin explants by reducing the expression levels of las and rhl quorum sensing systems and extracellular polymeric substance synthesis. Finally, lapA gene deletion also reduced the virulence of PAO1 in Caenorhabditis elegans in fast-kill and slow-kill infection assays. This study provides insights into the roles of lapA in modulating P. aeruginosa virulence and biofilm formation under phosphate depletion stress.

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Sulfane Sulfur Regulates LasR-Mediated Quorum Sensing and Virulence in Pseudomonas aeruginosa PAO1.

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