N-Undecanoyl cyclopentamide affects the biofilm and virulence of Pseudomonas aeruginosa

Abstract:

[Background] Biofilm formation is one of the major reasons for the increasing drug resistance of Pseudomonas aeruginosa, and the quorum sensing (QS) system plays a key role in biofilm formation. [Objective] QS inhibitors can inhibit the formation of biofilm and the secretion of virulence factors, serving as a new approach to address drug resistance. We chemically altered both the parent nucleus and acyl side chains of the las QS signaling molecule N-(3-oxododecanoyl)-l-homoserine lactone (OdDHL) to synthesize N-undecanoyl cyclopentamide, named Y0-C11-HSL, aiming to reveal the effects of Y0-C11-HSL on the biofilm formation and virulence factor secretion of P. aeruginosa and the underlying molecular mechanism. [Methods] Cystal violet staining and scanning electron microscopy (SEM) were employed to evaluate the effects of Y0-C11-HSL on the biofilm formation and structure. The inhibitory activity of Y0-C11-HSL was assessed by measuring the production and movement of virulence factors. The effect of Y0-C11-HSL on the surface chemical groups of extracellular polymers (EPS) was investigated by Fourier transform infrared spectrometry (FT-IR), and the mechanism of action of Y0-C11-HSL was studied by molecular docking. [Results] Compared with the control group, 10–200 μmol/L Y0-C11-HSL reduced the biofilm formation of P. aeruginosa, and the reduction rate reached 24.1% at 200μmol/L (P＜0.01). In addition, 200 μmol/L Y0-C11-HSL inhibited the secretion of pyocyanin, rhamnolipid, extracellular polysaccharide, and hydrolytic protease by P. aeruginosa, with the inhibition rates of 34.7% (P＜0.01), 33.1% (P＜0.01), 27.3% (P＜0.01), and 37.3% (P＜0.01), respectively. Furthermore, Y0-C11-HSL inhibited the swarming and twitching of P. aeruginosa, with the inhibition rates of 45.6% (P＜0.01) and 51.7% (P＜0.01), respectively, and it affected the EPS surface chemical groups. The molecular docking results showed that Y0-C11-HSL competitively bound to the OdDHL-bound LasR receptor. [Conclusion] Y0-C11-HSL could competitively bind to OdDHL-bound LasR receptor to affect the transcriptional proteins and thus down-regulate the expression of P. aeruginosa QS-related genes.