Iso-superoxide dismutase in <Emphasis Type="Italic">Deinococcus grandis</Emphasis>, a UV resistant bacterium |
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Authors: | Na-Rae Yun Young Nam Lee |
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Institution: | (1) Department of Microbiology, Chungbuk National University, Cheongju, 361-763, Republic of Korea |
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Abstract: | Deinococcus grandis possesses two types of superoxide dismutase (SOD, E. C. 1.15.1.1.) that show distinct electrophoretic behavior, one that
migrates slowly and the other that migrates rapidly (SOD-1 and SOD-2, respectively). In this study, SOD-1 was uniformly and
abundantly detected, regardless of growth phase, whereas SOD-2 was not detected during early growth, but was detectable from
the exponential growth phase. In addition, a substantial increase in SOD-2 was observed in cells that were treated with potassium
superoxide or UV, which suggests that SOD-2 is an inducible protein produced in response to stressful environments. Insensitivity
of SOD-1 to both H2O2 and cyanide treatment suggests that SOD-1 is MnSOD. However, SOD-2 would be FeSOD, since it lost activity in response to
H2O2 treatment, but not to cyanide. Localization studies of D. grandis iso-SODs in sucrose-shocked cells suggest that SOD-1 is a membrane-associated enzyme, whereas SOD-2 is a cytosolic enzyme.
In conclusion, SOD-1 seems to be an essential constitutive enzyme for viability and SOD-2 appears to be an inducible enzyme
that is probably critical for survival upon UV irradiation and oxidative stress. |
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Keywords: | Deinococcus grandis iso-SODs membrane bound SOD inducible cytosolic SOD |
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