Purification and characterization of Ag,Zn-superoxide dismutase from Saccharomyces cerevisiae exposed to silver.
Cu,Zn-superoxide dismutase plays an important role in protecting cells from oxygen toxicity by catalyzing the dismutation of superoxide anion into hydrogen peroxide and oxygen. In Saccharomyces cerevisiae Cu,Zn-superoxide dismutase is coregulated with copper-thionein by copper via the transcription factor ACE 1. We demonstrate here that presence of AgNO3 in the culture medium leads to a five times increase of Cu,Zn-superoxide dismutase mRNA, with a concomitant six times decrease of the enzyme activity. Susceptibility of yeast to silver was apparently inversely related to Cu,Zn-superoxide dismutase activity. From silver-treated yeast a Cu,Zn-superoxide dismutase with impaired dismutase function was purified and was shown to contain silver, which was located to the copper site. These data suggest that Cu,Zn-superoxide dismutase may play an additional direct role in the defense of S. cerevisiae against metal stress by functioning as metal chelator.
Ciriolo
M R
MR
Department of Biology, University of Rome Tor Vergata, Italy.
Civitareale
P
P
Carrì
M T
MT
De Martino
A
A
Galiazzo
F
F
Rotilio
G
G
D002455:Cell Division / Q000187:drug effects; D004578:Electron Spin Resonance Spectroscopy; D015966:Gene Expression Regulation, Fungal; D007525:Isoelectric Focusing; D012333:RNA, Messenger / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D012835:Silver Nitrate / Q000378:metabolism* / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
D012333:RNA, Messenger; D012835:Silver Nitrate; D013482:Superoxide Dismutase