Abstract
The enzyme superoxide dismutase is ubiquitous in aerobic organisms where it plays a major role in alleviating oxygen-radical toxicity. An insertion mutation introduced into the iron superoxide dismutase locus (designated sodB) of the cyanobacterium Synechococcus sp. PCC 7942 created a mutant strain devoid of detectable iron superoxide dismutase activity. Both wild-type and mutant strains exhibited similar photosynthetic activity and viability when grown with 17 mumol.m-2.s-1 illumination in liquid culture supplemented with 3% carbon dioxide. In contrast, the sodB mutant exhibited significantly greater damage to its photosynthetic system than the wild-type strain when grown under increased oxygen tension or with methyl viologen. Although damage occurs at both photosystems I and II, it is primarily localized at photosystem I in the sodB mutant. Growth in 100% molecular oxygen for 24 hr decreased photoacoustically measured energy storage in 3-(3,4-dichlorophenyl)-1,1-dimethylurea and abolished the fluorescence state 2 to state 1 transition in the sodB mutant, indicating interruption of cyclic electron flow around photosystem I. Analysis of the flash-induced absorption transient at 705 nm indicated that the interruption of cyclic electron flow occurred in the return part of the cycle, between the two [4 Fe-4 S] centers of photosystem I, FA and FB, and cytochrome f. Even though the sodB mutant was more sensitive to damage by active oxygen than wild-type cells, both strains were equally sensitive to the photoinhibition of photosystem II caused by exposure to strong light.
Full text
PDFImages in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Abeliovich A., Kellenberg D., Shilo M. Effect of photooxidative conditions on levels of superoxide dismutase in Anacystis nidulans. Photochem Photobiol. 1974 May;19(5):379–382. doi: 10.1111/j.1751-1097.1974.tb06526.x. [DOI] [PubMed] [Google Scholar]
- Asada K., Yoshikawa K., Takahashi M., Maeda Y., Enmanji K. Superoxide dismutases from a blue-green alga, Plectonema boryanum. J Biol Chem. 1975 Apr 25;250(8):2801–2807. [PubMed] [Google Scholar]
- Beyer W. F., Jr, Fridovich I. Assaying for superoxide dismutase activity: some large consequences of minor changes in conditions. Anal Biochem. 1987 Mar;161(2):559–566. doi: 10.1016/0003-2697(87)90489-1. [DOI] [PubMed] [Google Scholar]
- Herbert S. K., Fork D. C., Malkin S. Photoacoustic measurements in vivo of energy storage by cyclic electron flow in algae and higher plants. Plant Physiol. 1990 Nov;94(3):926–934. doi: 10.1104/pp.94.3.926. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Laudenbach D. E., Herbert S. K., McDowell C., Fork D. C., Grossman A. R., Straus N. A. Cytochrome c-553 is not required for photosynthetic activity in the cyanobacterium Synechococcus. Plant Cell. 1990 Sep;2(9):913–924. doi: 10.1105/tpc.2.9.913. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Laudenbach D. E., Trick C. G., Straus N. A. Cloning and characterization of an Anacystis nidulans R2 superoxide dismutase gene. Mol Gen Genet. 1989 Apr;216(2-3):455–461. doi: 10.1007/BF00334390. [DOI] [PubMed] [Google Scholar]
- Mannan R. M., Whitmarsh J., Nyman P., Pakrasi H. B. Directed mutagenesis of an iron-sulfur protein of the photosystem I complex in the filamentous cyanobacterium Anabaena variabilis ATCC 29413. Proc Natl Acad Sci U S A. 1991 Nov 15;88(22):10168–10172. doi: 10.1073/pnas.88.22.10168. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ohad I., Kyle D. J., Arntzen C. J. Membrane protein damage and repair: removal and replacement of inactivated 32-kilodalton polypeptides in chloroplast membranes. J Cell Biol. 1984 Aug;99(2):481–485. doi: 10.1083/jcb.99.2.481. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Prentki P., Krisch H. M. In vitro insertional mutagenesis with a selectable DNA fragment. Gene. 1984 Sep;29(3):303–313. doi: 10.1016/0378-1119(84)90059-3. [DOI] [PubMed] [Google Scholar]
- Radmer R. J., Kok B. Photoreduction of O(2) Primes and Replaces CO(2) Assimilation. Plant Physiol. 1976 Sep;58(3):336–340. doi: 10.1104/pp.58.3.336. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Samuelsson G., Lönneborg A., Gustafsson P., Oquist G. The Susceptibility of Photosynthesis to Photoinhibition and the Capacity of Recovery in High and Low Light Grown Cyanobacteria, Anacystis nidulans. Plant Physiol. 1987 Feb;83(2):438–441. doi: 10.1104/pp.83.2.438. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tsang E. W., Bowler C., Hérouart D., Van Camp W., Villarroel R., Genetello C., Van Montagu M., Inzé D. Differential regulation of superoxide dismutases in plants exposed to environmental stress. Plant Cell. 1991 Aug;3(8):783–792. doi: 10.1105/tpc.3.8.783. [DOI] [PMC free article] [PubMed] [Google Scholar]