Abstract
Vitamin E (α-tocopherol) is an antioxidant that quenches singlet oxygen and free radicals. However, the mechanism by which vitamin E protects photosystemII (PSII) against photooxidative stress remains unclear. In this study, we examined the role of vitamin E in the photoinhibition of PSII in a mutant of Synechocystis sp. PCC 6803 that lacks the synthesis of vitamin E.
The PSII activity of the mutant decreased more rapidly than that of wild type under strong light at 1,500 μE m-2 s-1, indicating that photoinhibition was promoted by the lack of vitamin E. In contrast, there was no difference in the progress of photodamage to PSII between the two types of cell in the presence of chloramphenicol. It appears that vitamin E protects PSII from photoinhibition by alleviating the inhibition of the repair of photodamaged PSII.
