Fucoxanthin-chlorophyll (Chl) a/c–binding proteins (FCPs) are light-harvesting pigment–protein complexes found in diatoms and brown algae. Due to the characteristic pigments, such as fucoxanthin and Chl c, FCPs can capture light energy in blue-to green regions. A pennate diatom Phaeodactylum tricornutum synthesizes a red-shifted form of FCP under weak or red light, extending a light-absorption ability to longer wavelengths. In the present study, we examined changes in light-harvesting and energy-transfer processes of P. tricornutum cells grown under white- and single-colored light-emitting diodes (LEDs). The red-shifted FCP appears in the cells grown under the green, yellow, and red LEDs, and exhibited a fluorescence peak around 714 nm. Additional energy-transfer pathways are established in the red-shifted FCP; two forms (F713 and F718) of low-energy Chl a work as energy traps at 77 K. Averaged fluorescence lifetimes are prolonged in the cells grown under the yellow and red LEDs, whereas they are shortened in the blue-LED-grown cells. Based on these results, we discussed the light-adaptation machinery of P. tricornutum cells involved in the red-shifted FCP.

岩藻黄质-叶绿素 (Chl) a / c结合蛋白 (FCP) 是在硅藻和褐藻中发现的捕光色素-蛋白质复合物。由于具有岩藻黄质和 Chl c等特征色素，FCP 可以捕获蓝色到绿色区域的光能。羽状硅藻Phaeodactylum tricornutum在弱光或红光下合成一种红移形式的 FCP，将光吸收能力扩展到更长的波长。在本研究中，我们研究了三角褐指藻的光捕获和能量转移过程的变化在白色和单色发光二极管 (LED) 下生长的细胞。红移的 FCP 出现在绿色、黄色和红色 LED 下生长的细胞中，并在 714 nm 附近表现出荧光峰。在红移的 FCP 中建立了额外的能量转移途径；两种形式（F713 和 F718）的低能量 Chl a在 77 K 下作为能量陷阱起作用。在黄色和红色 LED 下生长的细胞中，平均荧光寿命延长，而在蓝色 LED 生长的细胞中则缩短。基于这些结果，我们讨论了参与红移 FCP 的三角褐指藻细胞的光适应机制。