ompW is cooperatively upregulated by MarA and SoxS in response to menadione

Abstract

OmpW is a minor porin whose biological function has not been clearly defined. Evidence obtained in our laboratory indicates that in Salmonella enterica serovar Typhimurium the expression of OmpW is activated by SoxS upon exposure to paraquat and it is required for resistance. SoxS belongs to the AraC family of transcriptional regulators, like MarA and Rob. Due to their high structural similarity, the genes under their control have been grouped in the mar/sox/rob regulon, which presents a DNA-binding consensus sequence denominated the marsox box. In this work, we evaluated the role of the transcription factors MarA, SoxS and Rob of S. enterica serovar Typhimurium in regulating ompW expression in response to menadione. We determined the transcript and protein levels of OmpW in different genetic backgrounds; in the wild-type and Δrob strains ompW was upregulated in response to menadione, while in the ΔmarA and ΔsoxS strains the induction was abolished. In a double marA soxS mutant, ompW transcript levels were lowered after exposure to menadione, and only complementation in trans with both genes restored the positive regulation. Using transcriptional fusions and electrophoretic mobility shift assays with mutant versions of the promoter region we demonstrated that two of the predicted sites were functional. Additionally, we demonstrated that MarA increases the affinity of SoxS for the ompW promoter region. In conclusion, our study shows that ompW is upregulated in response to menadione in a cooperative manner by MarA and SoxS through a direct interaction with the promoter region.

Systems analysis of methylerythritol-phosphate pathway flux in E. coli: insights into the role of oxidative stress and the validity of lycopene as an isoprenoid reporter metabolite

“…We next tested whether measurable lycopene content could be decreased by high levels of intracellular ROS. Therefore, the high lycopene producer Seq + was treated with menadione, which induces ROS formation in E. coli [ 47 , 48 ]. The measurable lycopene content decreased significantly in the presence of sublethal doses of menadione (Fig.…”

MarA, SoxS and Rob of Escherichia coli – Global Regulators of Multidrug Resistance, Virulence and Stress Response

“…In contrast, deletion of marA did not affect the oral inoculation LD 50 values of Salmonella in mice [176]. Additionally, in WT strains, MarA and SoxS co-operatively induce the expression of ompW upon exposure of the bacteria to menadione [179]. OmpW is a minor immunogenic membrane porin that has been implicated in paraquat resistance, osmoprotection and hydrogen peroxide, and hypochlorous acid influx [179 and references therein].…”

“…Additionally, in WT strains, MarA and SoxS co-operatively induce the expression of ompW upon exposure of the bacteria to menadione [179]. OmpW is a minor immunogenic membrane porin that has been implicated in paraquat resistance, osmoprotection and hydrogen peroxide, and hypochlorous acid influx [179 and references therein]. OmpW has not been shown to be regulated by the TRs in E. coli , but other porins are under their control, suggesting a similar theme for both species (see section 5.2.2).…”

Effect of photooxidative stress and mannitol on synthesis of OmpC-OmpF proteins of Escherichia coli in lake water

“…Another study showed that the synthesis of OmpA was decreased by visible irradiation [20]. A study of oxidative stress showed that the amount of OmpW protein was increased 1.7 fold when Salmonella typhimurium was treated with the superoxidegenerating agent menadione [23]. Chou et al (1993) also showed that micF transcription was strongly inducible, but wholly-dependent, on the soxRS locus in response to treatment with the superoxide-generating agent Paraquat [24].…”