PsbU is a subunit of the extrinsic complex attached to the core of photosystem II. A PsbU-mutant of Synechococcus PCC 7942 was isolated based on its elevated resistance to externally applied oxidative stress. PsbU-mutant exhibits fast rates of degradation of the photosystem II core protein, D1, under sub-saturating as well as high-light conditions. While forward electron transfer is not affected, back electron flow is severely impaired in the mutant. We suggest that impairment of psbU results in production of reactive-oxygen-species, which trigger antioxidative mechanisms even under standard growth conditions. Accordingly, when challenged with external oxidative stress, these cells are more resistant than wild type cells.
Bibliographical noteFunding Information:
This study was supported by the Israel Science Foundation (Grant No. 683/03-17.1) and by the German Israel Foundation (Grant No. I-729-27.9/2002). Work in the laboratory of N.K. is carried out under the auspices of the Avron Even-Ari Minerva Center.
- D1 degradation
- Oxidative stress