PA1426 regulates Pseudomonas aeruginosa quorum sensing and virulence:an in vitro study

Objective:Pseudomonas aeruginosa(P.aeruginosa)contains a hierarchy of quorum sensing(QS)network,consisting of the las,rhl and pqs systems,which play a key role in coordinating the expression of virulence factors.PA2146 was found to be associated with P.aeruginosa pathogenicity in macrophage and host Immune response.The aim of this study was to investigate the effects of PA2146 on the virulence of P.aeruginosa and explore its mechanism.Methods:PA2146 gene knockout strain and complement strain of P.aeruginosa PAO1 were constructed.The biomass of biofilm was detected by crystal violet staining;the virulence factors were measured,including pyocyanin,rhamnolipid,LasA elastase,LasB elastase and hemolytic activity;RNA-seq and label-free relative quantitative proteomics analyses were carried out to test the influence of PA2146 on transcriptomics and proteomics.This study was approved by the Institutional Review Board of the Third Xiangya Hospital,Central South University,China(approval No.2019-S021).Results:PA2146-deficient strains showed reduced biofilm formation and increased pyocyanin,rhamnolipid,LasA elastase,LasB elastase,and hemolytic activity,as well as increased motility,compared with the wild-type strain.RNA-seq and label-free relative quantitative proteomics analyses revealed that PA2146 repressed the transcription of several genes that are integral to the pqs system and to pyocyanin biosynthesis,and increased the expression of MexEF-OprN efflux pump components at the gene and protein level.Conclusion:PA2146 gene was found to inhibit the pqs system.PA2146 may affect quorum sensing by directly inhibiting the pqs system or by enhancing the expression of MexEF-OprN efflux pump components,thereby promoting efflux of 2-heptyl-4(1H)-quinolone,a Pseudomonas quinolone signal precursor,and thus affecting P.aeruginosa virulence.