Copper (II) Ions Affect Escherichia coli Membrane Vesicles’ SH-Groups and a Disulfide-Dithiol Interchange Between Membrane Proteins

• Published in: Cell biochemistry and biophysics 2008-05, Vol.51 (1), p.45-50
• Main Authors: Kirakosyan, Gayane, Trchounian, Karen, Vardanyan, Zaruhi, Trchounian, Armen
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - metabolism; Adenosine Triphosphate - metabolism; Animals; ATP; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Biochemistry; Biological and Medical Physics; Biomedical and Life Sciences; Biophysics; Biotechnology; Cell Biology; Cell Membrane - chemistry; Cell Membrane - drug effects; Cell Membrane - metabolism; Cobalt; Cobalt - pharmacology; Copper; Copper - pharmacology; Cysteine; Disulfides - metabolism; E coli; Escherichia coli; Escherichia coli - cytology; Escherichia coli - drug effects; Escherichia coli - metabolism; Fermentation; Hydrogenase - genetics; Hydrogenase - metabolism; Ions; Life Sciences; Membrane Proteins - chemistry; Membrane Proteins - metabolism; Mutants; Mutation; Original Paper; Pharmacology/Toxicology; Sulfhydryl Compounds - metabolism; Zinc - pharmacology
• ISSN: 1085-9195; 1559-0283
• DOI: 10.1007/s12013-008-9014-7

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 F 0 F 1 -ATPase operation. The changes in the number of these groups by ATP are observed under certain conditions. In this study, copper ions (Cu 2+ ) 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 Cu 2+ in the presence of K + . Moreover, the increase in the number of SH-groups by Cu 2+ was absent as well as the inhibition in ATP-dependent increasing SH-groups number by Cu 2+ lacked when vesicles were treated with N -ethylmaleimide (NEM), specific thiol-reagent. Such an effect was not observed with zinc (Zn 2+ ), cobalt (Co 2+ ), 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 F 0 F 1 -ATPase or hydrogenase 3 (no activity of hydrogenase 4 was detected in the hyc mutant used). A direct effect of Cu 2+ but not Cu + on the F 0 F 1 -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.