A novel role for PsbO1 in photosynthetic electron transport as suggested by its light-triggered selective nitration in Arabidopsis thaliana
A novel role for PsbO1 in photosynthetic electron transport as suggested by its light-triggered selective nitration in Arabidopsis thaliana
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DOI：
10.1080/15592324.2018.1513298
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发表时间：
2018-09
影响因子：
2.9
通讯作者：
Misa Takahashi;H. Morikawa
中科院分区：
文献类型：
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作者：
Misa Takahashi;H. Morikawa
拟南芥叶片暴露于二氧化氮（NO2）会导致特定蛋白质（如PsbO1）的选择性硝化。PsbO1的第9个酪氨酸残基（9Tyr）被确定为硝化位点。这种硝化作用由光触发，由光合作用电子传递抑制剂抑制。在蛋白质硝化过程中，酪氨酸和NO2自由基同时形成，并迅速结合形成3-硝基酪氨酸。PsbO1的9Tyr的选择性氧化机制是必需的。我们假设，与D1的161Tyr类似，PsbO1的9Tyr在光照下通过光合电子传递选择性地氧化一个酪基自由基。在重新评估我们的析氧分析后，证实了PsbO1的硝化作用导致类囊体膜的析氧减少。据报道，NO2以亚硝酸的形式进入细胞，亚硝酸解离形成NO2−。NO2−可被出氧络合物氧化为NO2。光可以使这个反应与酪氨酸自由基的形成同步。这些发现提示PsbO1在光合电子传递中的新作用。
ABSTRACT Exposure of Arabidopsis leaves to nitrogen dioxide (NO2) results in the selective nitration of specific proteins, such as PsbO1. The 9th tyrosine residue (9Tyr) of PsbO1 has been identified as the nitration site. This nitration is triggered by light and inhibited by photosynthetic electron transport inhibitors. During protein nitration, tyrosyl and NO2 radicals are formed concurrently and combine rapidly to form 3-nitrotyrosine. A selective oxidation mechanism for 9Tyr of PsbO1 is required. We postulated that, similar to 161Tyr of D1, 9Tyr of PsbO1 is selectively photo-oxidized by photosynthetic electron transport in response to illumination to a tyrosyl radical. In corroboration, after reappraising our oxygen evolution analysis, the nitration of PsbO1 proved responsible for decreased oxygen evolution from the thylakoid membranes. NO2 is reportedly taken into cells as nitrous acid, which dissociates to form NO2−. NO2− may be oxidized into NO2 by the oxygen-evolving complex. Light may synchronize this reaction with tyrosyl radical formation. These findings suggest a novel role for PsbO1 in photosynthetic electron transport.