Affiliation:
1. University of Idaho, Biological Sciences Department, Moscow, Idaho 83844–3051
Abstract
Abstract
A strain ofSynechococcus sp. strain PCC 7942 with no functional Fe superoxide dismutase (SOD), designatedsodB−, 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 thesodB− 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, thesodB− 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.
Publisher
Oxford University Press (OUP)
Subject
Plant Science,Genetics,Physiology
Cited by
64 articles.
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