A Cyanobacterium Lacking Iron Superoxide Dismutase Is Sensitized to Oxidative Stress Induced with Methyl Viologen but Is Not Sensitized to Oxidative Stress Induced with Norflurazon1
AUTOR(ES)
Thomas, David J.
FONTE
American Society of Plant Physiologists
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=35068Documentos Relacionados
- Characterization of damage to photosystems I and II in a cyanobacterium lacking detectable iron superoxide dismutase activity.
- Escherichia coli iron superoxide dismutase targeted to the mitochondria of yeast cells protects the cells against oxidative stress.
- Mutations in PMR1 suppress oxidative damage in yeast cells lacking superoxide dismutase.
- Iron-Superoxide Dismutase Expression in Transgenic Alfalfa Increases Winter Survival without a Detectable Increase in Photosynthetic Oxidative Stress Tolerance1
- Overexpression of Iron Superoxide Dismutase in Transformed Poplar Modifies the Regulation of Photosynthesis at Low CO2 Partial Pressures or Following Exposure to the Prooxidant Herbicide Methyl Viologen1