| 9536078 |
Thomas DJ, Avenson TJ, Thomas JB, Herbert SK: A cyanobacterium lacking iron superoxide dismutase is sensitized to oxidative stress induced with methyl viologen but Is not sensitized to oxidative stress induced with norflurazon . Plant Physiol. 1998 Apr;116(4):1593-602.
A strain of Synechococcus sp. strain PCC 7942 with no functional Fe superoxide dismutase (SOD), designated sodB-, was characterized by its growth rate, photosynthetic pigments, and cyclic photosynthetic electron transport activity when treated with methyl viologen or norflurazon (NF). In their unstressed conditions, both the sodB- and wild-type strains had similar chlorophyll and carotenoid contents and catalase activity, but the wild type had a faster growth rate and higher cyclic electron transport activity. The sodB- was very sensitive to methyl viologen, indicating a specific role for the FeSOD in protection against superoxide generated in the cytosol. In contrast, the sodB- mutant was less sensitive than the wild type to oxidative stress imposed with NF. This suggests that the FeSOD does not protect the cell from excited singlet-state oxygen generated within the thylakoid membrane. Another up-regulated antioxidant, possibly the MnSOD, may confer protection against NF in the sodB- strain. These results support the hypothesis that different SODs have specific protective functions within the cell. |
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