The effect of ArcA on the growth, motility, biofilm formation, and virulence of Plesiomonas shigelloides

Abstract

Background The anoxic redox control binary system plays an important role in the response to oxygen as a signal in the environment. In particular, phosphorylated ArcA, as a global transcription factor, binds to the promoter regions of its target genes to regulate the expression of aerobic and anaerobic metabolism genes. However, the function of ArcA in Plesiomonas shigelloides is unknown. Results In the present study, P. shigelloides was used as the research object. The differences in growth, motility, biofilm formation, and virulence between the WT strain and the ΔarcA isogenic deletion mutant strain were compared. The data showed that the absence of arcA not only caused growth retardation of P. shigelloides in the log phase, but also greatly reduced the glucose utilization in M9 medium before the stationary phase. The motility of the ΔarcA mutant strain was either greatly reduced when grown in swim agar, or basically lost when grown in swarm agar. The electrophoretic mobility shift assay results showed that ArcA bound to the promoter regions of the flaK, rpoN, and cheV genes, indicating that ArcA directly regulates the expression of these three motility-related genes in P. shigelloides. Meanwhile, the ability of the ΔarcA strain to infect Caco-2 cells was reduced by 40%; on the contrary, its biofilm formation was enhanced. Furthermore, the complementation of the WT arcA gene from pBAD33-arcA+ was constructed and all of the above features of the pBAD33-arcA+ complemented strain were restored to the WT level. Conclusions We showed the effect of ArcA on the growth, motility, biofilm formation, and virulence of Plesiomonas shigelloides, and demonstrated that ArcA functions as a positive regulator controls the motility of P. shigelloides by directly regulating the expression of flaK, rpoN and cheV genes.

Fluoroquinolone Residues in the Environment Rapidly Induce Heritable Fluoroquinolone Resistance in Escherichia coli

“…Similarly, ciprofloxacin exposure (7 μg/L) significantly induced an increase in biofilm formation in the resistant mutants selected from ciprofloxacin exposure (CM10d, CM100d, and CM130d) (Kruskal–Wallis test, P < 0.05). However, the CM130d mutant maintained biofilm production ability after withdrawal of ciprofloxacin (Figure e), which could be caused by the mutation of genes associated with biofilm formation (e.g., arc A) . Indeed, this hypothesis was further confirmed by whole-genome sequencing, as discussed later.…”

“…However, the CM130d mutant maintained biofilm production ability after withdrawal of ciprofloxacin (Figure 1e), which could be caused by the mutation of genes associated with biofilm formation (e.g., arcA). 48 Indeed, this hypothesis was further confirmed by whole-genome sequencing, as discussed later. ROS, including superoxide, hydrogen peroxide, and hydroxyl radicals, are unfortunate byproducts of cellular respiration and redox-cycling process.…”

“…coli. , These reported phenomena were similar to the observed ciprofloxacin resistance of CM130d in this study (Figure d). Moreover, the biofilm formation ability of the arc A-deficient mutant was reported to be 21.56-fold higher than that of the wild-type strain, suggesting the negative regulation of arc A on biofilm formation . Consequently, mutation of arc A probably alleviated its repression to produce a higher biofilm formation by EM130d and CM130d than that by E.…”

“…Moreover, the biofilm formation ability of the arcA-deficient mutant was reported to be 21.56-fold higher than that of the wild-type strain, suggesting the negative regulation of arcA on biofilm formation. 48 Consequently, mutation of arcA probably alleviated its repression to produce a higher biofilm formation by EM130d and CM130d than that by E. coli K12 (Figure 1e), which was likely beneficial to the ciprofloxacin resistance of CM130d. 45 Nevertheless, the inconsistency of the resistance reversion between EM130d and CM130d in antibiotic-free conditions was likely contingent on the genetic background, 58 and the detailed mechanism as well as the roles of compensatory mutations should be further elucidated.…”

RpoN is required for the motility and contributes to the killing ability of Plesiomonas shigelloides

“…Growth assays were performed as described previously [ 85 ]. The WT, Δ rpoN , and Δ rpoN /pBAD33- rpoN + strains were cultured overnight at 37 °C with shaking in sterile LB medium.…”