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mgtA Expression is induced by rob overexpression and mediates a Salmonella enterica resistance phenotype

Julieta Barchiesi1, María E Castelli, Fernando C Soncini

  • 1Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas (UNR), Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Rosario, Argentina.

Journal of Bacteriology
|May 20, 2008
PubMed

Insights

Rob protein in Salmonella enhances bacterial resistance by upregulating the MgtA Mg2+ transporter, aiding in detoxification. This pathway is crucial for cyclohexane resistance, independent of the PhoP system.

Area of Science:

  • Microbiology
  • Bacterial Physiology
  • Molecular Biology

Background:

  • Rob is a transcriptional regulator involved in bacterial resistance.
  • Rob belongs to the Sox/Mar subfamily of AraC/XylS-type regulators.
  • These regulators influence multidrug, heavy metal, superoxide, and organic solvent resistance.

Purpose of the Study:

  • To investigate the role of Rob in regulating mgtA transcription in Salmonella enterica.
  • To determine the mechanism by which Rob induces mgtA expression.
  • To elucidate the contribution of MgtA to Rob-mediated bacterial resistance phenotypes.

Main Methods:

  • Overexpression of Rob in Salmonella enterica.
  • Analysis of mgtA gene transcription.
  • Investigation of Rob binding to the mgtA promoter region.
  • Assessment of bacterial resistance to cyclohexane.

Main Results:

  • Rob overexpression upregulates mgtA transcription in a PhoP-independent manner.
  • Rob binds to a conserved Mar/Sox/Rob motif upstream of the mgtA transcriptional start site.
  • Rob-induced mgtA expression confers low-level cyclohexane resistance.
  • mgtA is required for Rob-induced cyclohexane resistance when the AcrAB efflux pump is present.

Conclusions:

  • Rob directly induces mgtA transcription via a specific DNA binding mechanism.
  • MgtA plays a role in the AcrAB-mediated detoxification of cyclohexane promoted by Rob.
  • This study reveals a novel regulatory pathway for bacterial resistance to organic solvents.

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