Selective nitration of PsbO1 inhibits oxygen evolution from isolated Arabidopsis thylakoid membranes.
Treatment of isolated Arabidopsis thaliana thylakoid membranes with nitrogen dioxide (NO2) induces selective nitration of the tyrosine residue at the ninth amino acid (9Tyr) of PsbO1. This selective nitration is triggered by light and is inhibited by photosynthetic electron transport inhibitors. Therefore, we postulated that, similar to161Tyr of D1 (YZ),9Tyr of PsbO1 is redox active and is selectively oxidized by photosynthetic electron transport in response to illumination to a tyrosyl radical that is highly susceptible to nitration. This tyrosyl radical may combine rapidly at diffusion-controlled rates with NO2to form 3-nitrotyrosine. If this postulation is correct, the nitration of9Tyr of PsbO1 should decrease oxygen evolution activity. We investigated the effects of PsbO1 nitration on oxygen evolution from isolated thylakoid membranes, and found that nitration decreased oxygen evolution to ≥ 0% of the control. Oxygen evolution and nitration were significantly negatively correlated. This finding is consistent with redox active properties of the9Tyr gene of PsbO1, and suggests that PsbO19Tyr acts as an electron relay, such as YZin the photosystem II oxygenic electron transport chain.
a Department of Mathematical and Life Sciences , Graduate School of Science, Hiroshima University , Kagamiyama, Higashi-Hiroshima , Hiroshima , Japan.
Misa
M
Takahashi
a Department of Mathematical and Life Sciences , Graduate School of Science, Hiroshima University , Kagamiyama, Higashi-Hiroshima , Hiroshima , Japan.
Jun
J
Shigeto
a Department of Mathematical and Life Sciences , Graduate School of Science, Hiroshima University , Kagamiyama, Higashi-Hiroshima , Hiroshima , Japan.
Atsushi
A
Sakamoto
a Department of Mathematical and Life Sciences , Graduate School of Science, Hiroshima University , Kagamiyama, Higashi-Hiroshima , Hiroshima , Japan.
Hiromichi
H
Morikawa
D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D009585:Nitrogen Dioxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism*
D029681:Arabidopsis Proteins; D010940:Plant Proteins; D009585:Nitrogen Dioxide; D010100:Oxygen
Arabidopsis thaliana; PsbO1; PsbO2; nitrogen dioxide; oxygen evolution; photosynthetic electron transport; redox active; thylakoid membranes; tyrosine nitration; tyrosyl radical