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Reversible inhibition of photophosphorylation in chloroplasts by nitric oxide
Author(s) -
Takahashi Shunichi,
Yamasaki Hideo
Publication year - 2002
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 - 10.1016/s0014-5793(02)02244-5
Subject(s) - photophosphorylation , thylakoid , chemistry , chloroplast , nitric oxide , electron transport chain , bicarbonate , biochemistry , atp synthase , photosystem ii , biophysics , photosynthesis , tricine , chlorophyll , photochemistry , biology , enzyme , organic chemistry , gene
Nitric oxide (NO) is a bioactive molecule involved in diverse physiological functions in plants. Here we demonstrate that NO is capable of regulating the activity of photophosphorylation in chloroplasts. The electron transport activity in photosystem II determined from chlorophyll a fluorescence was inhibited by NO. NO also inhibited light‐induced ΔpH formation across the thylakoid membrane. High concentrations of nitrite and nitrate did not show such inhibitory effects, suggesting that the inhibition is not due to uncoupling effects of the oxidized products of NO. ATP synthesis activity upon illumination was severely inhibited by NO (IC 50 =0.7 μM). The inhibition was found to be temporary and the activity was completely recovered by removing NO. Bovine hemoglobin and bicarbonate were effective in preventing NO‐dependent inhibition of photophosphorylation. These results indicate that NO is a reversible inhibitor of photosynthetic ATP synthesis.