A Two-Component System FleS/FleR Regulates Multiple Virulence-Related Traits inPseudomonas aeruginosa

Abstract

Microorganisms commonly use two-component systems (TCSs) to detect specific environmental changes and respond accordingly for their own benefit. However, the regulatory mechanisms and physiological roles of a majority of TCSs are still elusive. In this study, we focused on a previously predicted TCS FleS/FleR in Pseudomonas aeruginosa to systematically investigate its regulation and physiological roles. Loss of fleS or fleR or both genes led to decreased biofilm formation and attenuated motility in PAO1, which could be restored by heterologously complementation of FleR but not FleS, confirming that the sensor kinase FleS and the response regulator FleR constitute a TCS pair. To determine the regulatory spectrum of this TCS, we conducted transcriptome sequencing and comparison between the wild-type strain and the fleR deletion mutant. The result showed that the TCS regulates about 440 genes including most of them are involved in the virulence-related pathways, e.g. siderophore biosynthesis, pyocyanin biosynthesis, type III/VI secretion systems, c-di-GMP metabolism, flagellar assembly etc. In addition to its roles in controlling biofilm formation and motility we have already shown, FleR was demonstrated to regulate the production of virulence factors such as pyocyanin and elastase, mediate stress response to SDS, and autoregulate its own expression. Moreover, EMSA assays revealed that FleR regulates flagellum biosynthesis genes flgBCDE, flgFGHIJKL, filC, which are essential for the bacterial motility, by directly interacting with their promoters. Taken together, these results expanded our understanding on the biological roles of FleS/FleR and provided new insights on its regulatory mechanisms.

Effect of non-glycosylated proteins from Melipona beecheii honey on the formation of Pseudomonas aeruginosa ATCC 27853 biofilm

“…Additionally, it has been reported that FleQ is related to the regulation of the cdrAB gene, which encodes for adhesin, which in turn is necessary for the early stages of P. aeruginosa bio lm formation (Baraquet and Harwood 2016). The eR gene encodes for the FleR protein, which forms a two-component FleS/FleR system to control P. aeruginosa bio lm formation and motility (Zhou et al 2021).…”

RclS Sensor Kinase Modulates Virulence of Pseudomonas capeferrum

“…The statistically significant increase of pseudobactin 358 production in Δ rclS mutant indicates the negative regulation of its production mediated by sensor kinase RclS. Previously, the role of FleS/FleR TCS in siderophore biosynthesis regulation in P. aeruginosa was described [ 37 ]. Moreover, this TCS regulates the secretion systems in P. aeruginosa [ 37 ], and a similar result has been obtained by KEGG analysis for RclSAR system of WCS358 in the stationary phase of growth.…”

“…Previously, the role of FleS/FleR TCS in siderophore biosynthesis regulation in P. aeruginosa was described [ 37 ]. Moreover, this TCS regulates the secretion systems in P. aeruginosa [ 37 ], and a similar result has been obtained by KEGG analysis for RclSAR system of WCS358 in the stationary phase of growth. This observation, as well as the results obtained from the cytotoxicity and adhesion tests performed on the keratinocyte cell line, indicates the role of RclS in P. capeferrum WCS358 virulence potential.…”

REC domain stabilizes the active heptamer of σ54-dependent transcription factor, FleR from Pseudomonas aeruginosa

“… 5 , 19 , 20 Class III genes, responsible for the formation of the flagellar hook and rod, fall under the control of FleSR. 17 , 21 , 22 Homologs of FleSR have been identified in other flagellated bacteria such as Vibrio cholera (FlrBC), Shewanella oneidensis (FlrBC), Campylobacter jejuni (FlgSR), and Helicobacter pylori (FlgSR). 23 , 24 , 25 , 26 , 27 Mutants of fleS or fleR are non-motile and significantly less virulent in P. aeruginosa .…”