Kim F J, Kim H P, Hah Y C, Roe J H
Department of Microbiology, College of Natural Sciences, Seoul National University, Korea.
Eur J Biochem. 1996 Oct 1;241(1):178-85. doi: 10.1111/j.1432-1033.1996.0178t.x.
Streptomyces coelicolor contains two distinct superoxide dismutase (SOD) activities detected on native PAGE. The level of each changed differently depending on growth media and scarcely responded to paraquat, a superoxide-generating agent. The total SOD activity doubled in late exponential phase compared with that in mid-exponential phase and less than double upon treatment with plumbagin, another superoxide-generating agent. The two SODs from S. coelicolor ATCC 10147 (Müller) strain were purified to near homogeneity. SOD1, a tetramer of 13.4-kDa subunits, was found to be a novel type of SOD containing 0.74 mol nickel/mol subunit as determined by atomic absorption spectroscopy. SOD2, a tetramer of 22.2-kDa subunits, was found to contain 0.36 mol iron and 0.26 mol zinc/mol subunit. The N-terminal amino acid sequences of both SODs were determined. SOD2 is similar to manganese-containing superoxide dismutases (MnSODs) and iron-containing superoxide dismutases (FeSODs) from other organisms, whereas SOD1 is less similar to known SODs but still contains a few conserved amino acids. The effects of metals and chelating agents on the expression of these two SODs were examined. The presence of nickel at micromolar concentrations in growth media induced the expression of SOD1 (nickel-containing superoxide dismutase; NiSOD), whereas the expression of SOD2 (iron/zinc-containing superoxide dismutase; FeZnSOD) was repressed. The changes in SOD activities were positively correlated with the amount of each enzyme as determined by immunoblotting, suggesting that metals do not modulate the activity per se but the amount of each protein.
天蓝色链霉菌在非变性聚丙烯酰胺凝胶电泳（native PAGE）上检测到两种不同的超氧化物歧化酶（SOD）活性。每种活性的水平根据生长培养基的不同而有不同变化，并且对百草枯（一种超氧化物产生剂）几乎没有反应。与指数中期相比，总SOD活性在指数后期增加了一倍，在用另一种超氧化物产生剂白花丹素处理后增加不到一倍。从天蓝色链霉菌ATCC 10147（Müller）菌株中纯化出两种SOD，纯度接近均一。通过原子吸收光谱法测定，SOD1是由13.4 kDa亚基组成的四聚体，是一种新型SOD，每个亚基含有0.74 mol镍。SOD2是由22.2 kDa亚基组成的四聚体，每个亚基含有0.36 mol铁和0.26 mol锌。测定了两种SOD的N端氨基酸序列。SOD2与其他生物的含锰超氧化物歧化酶（MnSODs）和含铁超氧化物歧化酶（FeSODs）相似，而SOD1与已知的SODs相似性较低，但仍含有一些保守氨基酸。研究了金属和螯合剂对这两种SOD表达的影响。生长培养基中微摩尔浓度的镍诱导SOD1（含镍超氧化物歧化酶；NiSOD）的表达，而SOD2（含铁/锌超氧化物歧化酶；FeZnSOD）的表达受到抑制。通过免疫印迹法测定，SOD活性的变化与每种酶的量呈正相关，这表明金属本身并不调节活性，而是调节每种蛋白质的量。
