Copper resistance in Pseudomonas syringae mediated by periplasmic and outer membrane proteins

Proc Natl Acad Sci U S A. 1991 Oct 15;88(20):8915-9. doi: 10.1073/pnas.88.20.8915.


Copper-resistant strains of Pseudomonas syringae pathovar tomato accumulate copper and develop blue colonies on copper-containing media. Three of the protein products of the copper-resistance operon (cop) were characterized to provide an understanding of the copper-resistance mechanism and its relationship to copper accumulation. The Cop proteins, CopA (72 kDa), CopB (39 kDa), and CopC (12 kDa), were produced only under copper induction. CopA and CopC were periplasmic proteins and CopB was an outer membrane protein. Leader peptide sequences of CopA, CopB, and CopC were confirmed by amino-terminal peptide sequencing. CopA, CopB, and CopC were purified from strain PT23.2, and their copper contents were determined. One molecule of CopA bound 10.9 +/- 1.2 atoms of copper and one molecule of CopC bound 0.6 +/- 0.1 atom of copper. The Cop proteins apparently mediate sequestration of copper outside of the cytoplasm as a copper-resistance mechanism.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Outer Membrane Proteins / biosynthesis
  • Bacterial Outer Membrane Proteins / genetics*
  • Bacterial Proteins / analysis
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / genetics
  • Cation Transport Proteins*
  • Copper / metabolism
  • Copper / pharmacology*
  • Drug Resistance, Microbial / genetics
  • Immunoblotting
  • Molecular Sequence Data
  • Molecular Weight
  • Operon*
  • Protein Sorting Signals / genetics
  • Pseudomonas / drug effects
  • Pseudomonas / genetics*
  • Recombinant Fusion Proteins / analysis


  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Cation Transport Proteins
  • CopA protein, Bacteria
  • CopC protein, Bacteria
  • Protein Sorting Signals
  • Recombinant Fusion Proteins
  • Copper