Identification of Three Superoxide dismutase Genes from a Geobacillus sp. |
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| Authors: | Yuanyuan Zou Ling Yang Guoxian Liu Yinv Li Yuexiong Zhu Zhifang Zhang |
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| Affiliation: | (1) Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, 100081 Beijing, China;(2) Basic Medical and Biological Sciences College, Soochow University, No. 199 Wuzhong Renai Street, 215123 Suzhou, China; |
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| Abstract: | We report the characterization of three Superoxide dismutase (sod) genes isolated from a bacterium in the Geobacillus genus. We isolated the bacterium from high-temperature pond mud and used 16S rRNA gene sequence to confirm its identity in the Geobacillus genus. The three genes Mn-sod, Fe/Mn-sod, and Cu/Zn-sod were cloned and analyzed. Their open reading frames are Mn-sod: 615 bp encoding a 204 amino acid protein; Fe/Mn-sod: 1,236 bp encoding a 411 amino acid protein; Cu/Zn-sod: 522 bp encoding a 173 amino acid protein. When these sod genes were expressed in Escherichia coli, only Mn-SOD was able to be purified. The activity of the purified Mn-SOD we got was about 2,730 U/mg. Studies of this Mn-SOD showed that it was thermostable at 60°, had 70% activity at 80° after 2.5 h, and still had 30% activity at 90° after 2.5 h. Mn-SOD activity required the ion Mn2+. Based on gel electrophoresis, we deduced that this Mn-SOD was a homotetramer. No activity was detected after the other two genes (Fe/Mn-sod, Cu/Zn-sod) were expressed in Escherichia coli, but activities were detected when expressed in Pichia pastoris. |
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