An antirepressor, SrpR, is involved in transcriptional regulation of the SrpABC solvent tolerance efflux pump of Pseudomonas putida S12

J Bacteriol. 2011 Jun;193(11):2717-25. doi: 10.1128/JB.00149-11. Epub 2011 Mar 25.


Organic compounds exhibit various levels of toxicity toward living organisms based upon their ability to insert into biological membranes and disrupt normal membrane function. The primary mechanism responsible for organic solvent tolerance in many bacteria is energy-dependent extrusion via efflux pumps. One such bacterial strain, Pseudomonas putida S12, is known for its high tolerance to organic solvents as provided through the SrpABC resistance-nodulation-cell division (RND) family efflux pump. To determine how two putative regulatory proteins (SrpR and SrpS, encoded directly upstream of the SrpABC structural genes) influence SrpABC efflux pump expression, we conducted transcriptional analysis, β-galactosidase fusion experiments, electrophoretic mobility shift assays, and pulldown analysis. Together, the results of these experiments suggest that expression of the srpABC operon can be derepressed by two distinct but complementary mechanisms: direct inhibition of the SrpS repressor by organic solvents and binding of SrpS by its antirepressor SrpR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artificial Gene Fusion
  • Bacterial Proteins / biosynthesis
  • DNA, Bacterial / metabolism
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial*
  • Genes, Reporter
  • Membrane Transport Proteins / biosynthesis*
  • Organic Chemicals / metabolism
  • Organic Chemicals / toxicity
  • Promoter Regions, Genetic
  • Protein Binding
  • Pseudomonas putida / genetics*
  • Pseudomonas putida / metabolism*
  • Repressor Proteins / antagonists & inhibitors*
  • Solvents / metabolism
  • Solvents / toxicity
  • Transcription Factors / metabolism*
  • Transcription, Genetic*
  • beta-Galactosidase / biosynthesis
  • beta-Galactosidase / genetics


  • Bacterial Proteins
  • DNA, Bacterial
  • Membrane Transport Proteins
  • Organic Chemicals
  • Repressor Proteins
  • Solvents
  • SrpA protein, Pseudomonas
  • SrpB protein, Pseudomonas putida
  • SrpC protein, Pseudomonas
  • Transcription Factors
  • beta-Galactosidase