Ciriolo M R, Civitareale P, Carrì M T, De Martino A, Galiazzo F, Rotilio G
Department of Biology, University of Rome Tor Vergata, Italy.
J Biol Chem. 1994 Oct 14;269(41):25783-7.
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.
铜锌超氧化物歧化酶通过催化超氧阴离子歧化为过氧化氢和氧气，在保护细胞免受氧毒性方面发挥着重要作用。在酿酒酵母中，铜锌超氧化物歧化酶通过转录因子ACE 1与铜硫蛋白共同受铜的调控。我们在此证明，培养基中硝酸银的存在会导致铜锌超氧化物歧化酶mRNA增加五倍，同时酶活性下降六倍。酵母对银的敏感性显然与铜锌超氧化物歧化酶活性呈负相关。从经银处理的酵母中纯化出一种歧化酶功能受损的铜锌超氧化物歧化酶，结果显示其含有银，且银位于铜位点。这些数据表明，铜锌超氧化物歧化酶可能通过作为金属螯合剂，在酿酒酵母抵御金属胁迫方面发挥额外的直接作用。
