Luu Trinh Mai Duy, Miyazaki Daichi, Ono Sumire, Nomata Jiro, Kono Masaru, Mino Hiroyuki, Niwa Tatsuya, Okegawa Yuki, Motohashi Ken, Taguchi Hideki, Hisabori Toru, Masuda Shinji
Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
iScience. 2021 Jan 13;24(2):102059. doi: 10.1016/j.isci.2021.102059. eCollection 2021 Feb 19.
In natural habitats, plants have developed sophisticated regulatory mechanisms to optimize the photosynthetic electron transfer rate at the maximum efficiency and cope with the changing environments. Maintaining proper P700 oxidation at photosystem I (PSI) is the common denominator for most regulatory processes of photosynthetic electron transfers. However, the molecular complexes and cofactors involved in these processes and their function(s) have not been fully clarified. Here, we identified a redox-active chloroplast protein, the triplet-cysteine repeat protein (TCR). TCR shared similar expression profiles with known photosynthetic regulators and contained two triplet-cysteine motifs (CxxxCxxxC). Biochemical analysis indicated that TCR localizes in chloroplasts and has a [3Fe-4S] cluster. Loss of TCR limited the electron sink downstream of PSI during dark-to-light transition. double mutant reduced growth significantly and showed unusual oxidation and reduction of plastoquinone pool. These results indicated that TCR is involved in electron flow(s) downstream of PSI, contributing to P700 oxidation.
在自然栖息地中，植物已经进化出复杂的调节机制，以最大效率优化光合电子传递速率，并应对不断变化的环境。在光系统I（PSI）中维持适当的P700氧化是光合电子传递大多数调节过程的共同特征。然而，参与这些过程的分子复合物和辅因子及其功能尚未完全阐明。在这里，我们鉴定出一种具有氧化还原活性的叶绿体蛋白，即三联体半胱氨酸重复蛋白（TCR）。TCR与已知的光合调节因子具有相似的表达谱，并包含两个三联体半胱氨酸基序（CxxxCxxxC）。生化分析表明，TCR定位于叶绿体中，并具有一个[3Fe-4S]簇。TCR的缺失限制了暗-光转换期间PSI下游的电子汇。双突变体显著降低了生长，并表现出质体醌库异常的氧化和还原。这些结果表明，TCR参与PSI下游的电子流，有助于P700氧化。
