Suppression of copper-induced cellular damage by copper sequestration with S100b protein.
We previously reported that S100b protein (homodimer of S100 beta subunit) can bind copper ions with a submicromolar dissociation constant (T. Nishikawa et al., J. Biol. Chem. 272, 23037-23041, 1997). In this study, a question was addressed as to whether this protein can sequester copper ions in an in vivo situation. Escherichia coli cells that had been rendered able to produce a fusion protein of rat S100 beta subunit with glutathione S-transferase displayed a marked resistance to cellular damage induced by copper alone or its combination with H2O2, compared with control cells expressing the transferase moiety only. A study by gel chromatography showed that about half of the expressed S100 beta fusion protein in the cytosol of copper-treated cells was eluted in the void volume fraction (molecular mass > 200 kDa), which contained most of the copper incorporated. The S100 beta fusion protein purified from the void volume fraction was found to contain 82% of the total copper in the fraction, while in a parallel experiment with the control cells, the glutathione S-transferase eluted in the void volume fraction contained only 18% of the total copper. Thus, it is clear that extraneously expressed S100b protein can acts as a "copper sink," thereby protecting E. coli cells from copper-induced cellular damage.
Shiraishi
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Department of Biochemistry, Wakayama Medical College, Japan.
Nishikimi
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M
D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000378:metabolism* / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D005982:Glutathione Transferase / Q000235:genetics; D008826:Microbial Sensitivity Tests; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D014162:Transfection
D002135:Calcium-Binding Proteins; D009414:Nerve Growth Factors; D011993:Recombinant Fusion Proteins; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579158:S100b protein, rat; D003300:Copper; D005982:Glutathione Transferase