Tocopherol controls D1 amino acid oxidation by oxygen radicals in Photosystem II
Journal Article
·
· Proceedings of the National Academy of Sciences of the United States of America
- Palacký Univ., Olomouc (Czech Republic). Faculty of Science. Centre of the Region Haná for Biotechnological and Agricultural Research. Dept. of Biophysics; Louisiana State Univ., Baton Rouge, LA (United States)
- Palacký Univ., Olomouc (Czech Republic). Faculty of Science. Centre of the Region Haná for Biotechnological and Agricultural Research. Dept. of Biophysics
- Palacký Univ., Olomouc (Czech Republic). Faculty of Science. Dept. of Botany
- Louisiana State Univ., Baton Rouge, LA (United States). Division of Biochemistry and Molecular Biology. Dept. of Biological Sciences
- Univ. of Cincinnati, OH (United States). Dept. of Chemistry. The Rieveschl Laboratories for Mass Spectrometry
Photosystem II (PSII) is an intrinsic membrane protein complex that functions as a light-driven water:plastoquinone oxidoreductase in oxygenic photosynthesis. Electron transport in PSII is associated with formation of reactive oxygen species (ROS) responsible for oxidative modifications of PSII proteins. In this study, oxidative modifications of the D1 and D2 proteins by the superoxide anion (O2•-) and the hydroxyl (HO•) radicals were studied in WT and a tocopherol cyclase (vte1) mutant, which is deficient in the lipid-soluble antioxidant α-tocopherol. In the absence of this antioxidant, high-resolution tandem mass spectrometry was used to identify oxidation of D1:130E to hydroxyglutamic acid by O2•- at the PheoD1 site. Additionally, D1:246Y was modified to either tyrosine hydroperoxide or dihydroxyphenylalanine by O2•- and HO•, respectively, in the vicinity of the nonheme iron. We propose that α-tocopherol is localized near PheoD1 and the nonheme iron, with its chromanol head exposed to the lipid–water interface. This helps to prevent oxidative modification of the amino acid’s hydrogen that is bonded to PheoD1 and the nonheme iron (via bicarbonate), and thus protects electron transport in PSII from ROS damage.
- Research Organization:
- Louisiana State Univ., Baton Rouge, LA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- FG02-98ER20310
- OSTI ID:
- 1850186
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 4 Vol. 118; ISSN 0027-8424
- Publisher:
- National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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