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Enhancement of excitation-energy quenching in fucoxanthin chlorophyll a/c-binding proteins isolated from a diatom Phaeodactylum tricornutum upon excess-light illumination
Biochimica et Biophysica Acta (BBA) - Bioenergetics ( IF 4.3 ) Pub Date : 2020-12-04 , DOI: 10.1016/j.bbabio.2020.148350
Ryo Nagao , Makio Yokono , Yoshifumi Ueno , Takehiro Suzuki , Minoru Kumazawa , Ka-Ho Kato , Naoki Tsuboshita , Naoshi Dohmae , Kentaro Ifuku , Jian-Ren Shen , Seiji Akimoto

Photosynthetic organisms regulate pigment composition and molecular oligomerization of light-harvesting complexes in response to solar light intensities, in order to improve light-harvesting efficiency. Here we report excitation-energy dynamics and relaxation of fucoxanthin chlorophyll a/c-binding protein (FCP) complexes isolated from a diatom Phaeodactylum tricornutum grown under high-light (HL) illumination. Two types of FCP complexes were prepared from this diatom under the HL condition, whereas one FCP complex was isolated from the cells grown under a low-light (LL) condition. The subunit composition and oligomeric states of FCP complexes under the HL condition are different from those under the LL condition. Absorption and fluorescence spectra at 77 K of the FCP complexes also vary between the two conditions, indicating modifications of the pigment composition and arrangement upon the HL illumination. Time-resolved fluorescence curves at 77 K of the FCP complexes under the HL condition showed shorter lifetime components compared with the LL condition. Fluorescence decay-associated spectra at 77 K showed distinct excitation-energy-quenching components and alterations of energy-transfer pathways in the FCP complexes under the HL condition. These findings provide insights into molecular and functional mechanisms of the dynamic regulation of FCPs in this diatom under excess-light conditions.



中文翻译:

过量光照射下,从硅藻硅藻(Phaeodactylum tricornutum)分离的岩藻黄质叶绿素a / c结合蛋白中激发能猝灭的增强

光合生物响应于太阳光强度来调节光捕获复合物的颜料组成和分子低聚,以提高光捕获效率。在这里,我们报告激发能量动力学和岩藻黄质叶绿素a / c结合蛋白(FCP)复杂从硅藻Phaeodactylum tricornutum分离的复合物在强光(HL)照明下生长。在HL条件下,由该硅藻制备了两种类型的FCP复合物,而从在弱光(LL)条件下生长的细胞中分离出一种FCP复合物。HL条件下FCP复合物的亚基组成和低聚状态与LL条件下不同。在两种条件下,FCP配合物在77 K处的吸收光谱和荧光光谱也有所变化,这表明在HL照明下颜料成分和排列方式发生了改变。与LL条件相比,HL条件下FCP配合物在77 K处的时间分辨荧光曲线显示出较短的寿命成分。在HL条件下,FCP配合物在77 K处的荧光衰减相关光谱显示出独特的激发-能量猝灭成分和能量转移途径的变化。这些发现提供了在过量光照条件下该硅藻中FCPs动态调节的分子和功能机理的见解。

更新日期:2020-12-14
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