Proteomic identification of the Cus system as a major determinant of constitutive Escherichia coli silver resistance of chromosomal origin

J Proteome Res. 2008 Jun;7(6):2351-6. doi: 10.1021/pr700646b. Epub 2008 Apr 18.

Abstract

Although silver is one of the most potent and rapidly acting toxic metals to bacteria, silver-resistant bacteria do exist with low incidence. A proteomic approach was employed to identify the silver resistance determinants of a silver-resistant Escherichia coli strain isolated from stepwise selection against increasing concentrations of silver (Li et al. J. Bacteriol 1997, 179, 6127-32). Two-dimensional gel electrophoresis and mass spectrometry analysis revealed that members of the CusCFBA copper/silver chemiosmotic efflux system were highly expressed in the silver-resistant strain but undetectable in the parental silver-sensitive strain. Disruption of the cus locus of the silver-resistant strain resulted in a decrease of the minimum inhibitory concentration of Ag (+) from more than 1 mM to 12 microM. These results suggest that the chromosomally encoded Cus system, which naturally controls the periplasmic copper concentrations, is selectable to confer a constitutive silver resistance phenotype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Outer Membrane Proteins / analysis
  • Bacterial Outer Membrane Proteins / metabolism
  • Cation Transport Proteins / analysis
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism*
  • Copper Sulfate / pharmacology
  • Copper Transport Proteins
  • Drug Resistance, Bacterial*
  • Electrophoresis, Gel, Two-Dimensional
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / analysis
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Gene Deletion
  • Mutation
  • Proteomics / methods
  • Silver / pharmacology*
  • Silver Nitrate / pharmacology
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Tandem Mass Spectrometry

Substances

  • Bacterial Outer Membrane Proteins
  • Cation Transport Proteins
  • Copper Transport Proteins
  • CusF protein, E coli
  • Escherichia coli Proteins
  • OMPA outer membrane proteins
  • Silver
  • Silver Nitrate
  • Copper Sulfate