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Oxidation of the plastoquinone pool in chloroplast thylakoid membranes by superoxide anion radicals
Author(s) -
BorisovaMubarakshina Maria M.,
Naydov Ilya A.,
Ivanov Boris N.
Publication year - 2018
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13237
Subject(s) - thylakoid , plastoquinone , chemistry , photochemistry , superoxide , electron transport chain , redox , chloroplast , photosystem ii , photosystem i , radical , biophysics , biochemistry , photosynthesis , biology , inorganic chemistry , enzyme , gene
The plastoquinone (PQ)‐pool in chloroplast thylakoid membranes is a key electron carrier in the photosynthetic electron transport chain (PETC), and its redox state plays an essential role in the control of plant metabolism. Oxygen reduction in thylakoid membranes produces superoxide anion radicals ( O 2 · −), which may react with the PQ‐pool. Here, using isolated thylakoids, we show for the first time the oxidation of the PQ‐pool by O 2 · −. The xanthine‐xanthine oxidase system was used to supply O 2 · −externally to the thylakoid membrane and the redox state of the PQ‐pool was monitored by tracking chlorophyll a fluorescence. We propose that, in vivo , the reaction of O 2 · −produced in Photosystem I with reduced PQ (plastohydroquinone) creates hydrogen peroxide, which serves as a messenger that signals the redox state of the PETC.