Copper (II) ions affect Escherichia coli membrane vesicles' SH-groups and a disulfide-dithiol interchange between membrane proteins

Cell Biochem Biophys. 2008;51(1):45-50. doi: 10.1007/s12013-008-9014-7. Epub 2008 May 6.

Abstract

The SH-groups in Escherichia coli membrane vesicles, prepared from cells grown in fermentation conditions on glucose at slightly alkaline pH, have a role in the F0F1-ATPase operation. The changes in the number of these groups by ATP are observed under certain conditions. In this study, copper ions (Cu2+) in concentration of 0.1 mM were shown to increase the number of SH-groups in 1.5- to 1.6-fold independent from K+ ions, and the suppression of the increased level of SH-groups by ATP was determined for Cu2+ in the presence of K+. Moreover, the increase in the number of SH-groups by Cu2+ was absent as well as the inhibition in ATP-dependent increasing SH-groups number by Cu2+ lacked when vesicles were treated with N-ethylmaleimide (NEM), specific thiol-reagent. Such an effect was not observed with zinc (Zn2+), cobalt (Co2+), or Cu+ ions. The increased level of SH-groups was observed in the hycE or hyfR mutants with defects in hydrogenases 3 or 4, whereas the ATP-dependent increase in the number of these groups was determined in hycE not in hyfR mutants. Both changes in SH-groups number disappeared in the atp or hyc mutants deleted for the F0F1-ATPase or hydrogenase 3 (no activity of hydrogenase 4 was detected in the hyc mutant used). A direct effect of Cu2+ but not Cu+ on the F0F1-ATPase is suggested to lead to conformational changes or damaging consequences, increasing accessible SH-groups number and disturbing disulfide-dithiol interchange within a protein-protein complex, where this ATPase works with K+ uptake system or hydrogenase 4 (Hyd-4); breaks in disulfides are not ruled out.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism
  • Adenosine Triphosphate / metabolism
  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Cell Membrane / chemistry
  • Cell Membrane / drug effects*
  • Cell Membrane / metabolism
  • Cobalt / pharmacology
  • Copper / pharmacology*
  • Cysteine
  • Disulfides / metabolism*
  • Escherichia coli / cytology
  • Escherichia coli / drug effects
  • Escherichia coli / metabolism*
  • Fermentation
  • Hydrogenase / genetics
  • Hydrogenase / metabolism
  • Membrane Proteins / chemistry*
  • Membrane Proteins / metabolism*
  • Mutation
  • Sulfhydryl Compounds / metabolism*
  • Zinc / pharmacology

Substances

  • Bacterial Proteins
  • Disulfides
  • Membrane Proteins
  • Sulfhydryl Compounds
  • Cobalt
  • Copper
  • Adenosine Triphosphate
  • Hydrogenase
  • Adenosine Triphosphatases
  • Zinc
  • Cysteine