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

B Collao1, E H Morales1, F Gil1

  • 1Laboratorio de Microbiología Molecular, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.

Microbiology (Reading, England)
|February 9, 2013
PubMed

Insights

Salmonella enterica serovar Typhimurium

Area of Science:

  • Microbiology
  • Molecular Biology
  • Bacterial Genetics

Background:

  • OmpW is a minor porin in Salmonella enterica serovar Typhimurium with an undefined biological role.
  • OmpW expression is regulated by SoxS upon exposure to oxidative stress agents like paraquat.
  • MarA, SoxS, and Rob are transcriptional regulators belonging to the AraC family, controlling genes within the mar/sox/rob regulon.

Purpose of the Study:

  • To investigate the roles of MarA, SoxS, and Rob transcription factors in regulating ompW expression in Salmonella enterica serovar Typhimurium.
  • To elucidate the regulatory mechanism of ompW expression in response to menadione exposure.
  • To determine the cooperative interaction between transcription factors at the ompW promoter.

Main Methods:

  • Analysis of OmpW transcript and protein levels in wild-type and mutant Salmonella strains (Δrob, ΔmarA, ΔsoxS, ΔmarA soxS).
  • Transcriptional fusion assays to assess promoter activity.
  • Electrophoretic mobility shift assays (EMSA) to study transcription factor-DNA interactions.

Main Results:

  • OmpW expression was upregulated by menadione in wild-type and Δrob strains.
  • Menadione-induced upregulation of ompW was abolished in ΔmarA and ΔsoxS mutant strains.
  • MarA and SoxS cooperatively regulate ompW expression, with MarA enhancing SoxS binding to the ompW promoter.

Conclusions:

  • OmpW is upregulated in response to menadione in Salmonella enterica serovar Typhimurium.
  • The upregulation of ompW is a cooperative process mediated by the MarA and SoxS transcription factors.
  • MarA and SoxS directly interact with the ompW promoter region to control its expression.

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