Takahashi Misa, Shigeto Jun, Sakamoto Atsushi, Morikawa Hiromichi
a Department of Mathematical and Life Sciences , Graduate School of Science, Hiroshima University , Kagamiyama, Higashi-Hiroshima , Hiroshima , Japan.
Plant Signal Behav. 2016 Dec;11(12):e1263413. doi: 10.1080/15592324.2016.1263413.
PsbO1 is exclusively nitrated when isolated thylakoid membranes are incubated in a buffer bubbled with nitrogen dioxide (NO) containing NO and nitrite. NO is the primary intermediate for this selective nitration. Isolated thylakoid membranes were incubated in NO-bubbled buffer at 25°C in the light or dark. Protein analysis confirmed the selective nitration of PsbO1. Illumination was found to be essential in PsbO1 nitration. A nitration mechanism whereby nitratable tyrosine residues of PsbO1 are, prior to nitration, selectively photo-oxidized by photosynthetic electron transport to tyrosyl radicals to combine with NO to form 3-nitrotyrosine was hypothesized. We tested the electron transport inhibitors 3-(3,4-dichlorophenyl)-1,1- dimethylurea, sodium azide, and 1,5-diphenylcarbazide and found distinct inhibition of nitration of PsbO1. We also propose a possible nitration mechanism.
当分离的类囊体膜在含有一氧化氮（NO）和亚硝酸盐的二氧化氮（NO₂）鼓泡缓冲液中孵育时，PsbO1会被特异性硝化。NO是这种选择性硝化的主要中间体。将分离的类囊体膜在25°C下于光照或黑暗条件下在NO鼓泡缓冲液中孵育。蛋白质分析证实了PsbO1的选择性硝化。结果发现光照对PsbO1硝化至关重要。我们推测了一种硝化机制，即PsbO1中可硝化的酪氨酸残基在硝化之前先被光合电子传递选择性光氧化为酪氨酸自由基，然后与NO结合形成3-硝基酪氨酸。我们测试了电子传递抑制剂3-(3,4-二氯苯基)-1,1-二甲基脲、叠氮化钠和1,5-二苯基卡巴腙，发现它们对PsbO1硝化有明显抑制作用。我们还提出了一种可能的硝化机制。
