Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
J Phys Chem Lett. 2023 Sep 7;14(35):7967-7974. doi: 10.1021/acs.jpclett.3c01633. Epub 2023 Aug 30.
Fucoxanthin-chlorophyll proteins (FCPs) are a family of photosynthetic light-harvesting complex (LHC) proteins found in diatoms. They efficiently capture photons and regulate their functions, ensuring diatom survival in highly fluctuating light. FCPs are present in different oligomeric states , but functional differences among these FCP oligomers are not yet fully understood. Here we characterized two types of antenna complexes (FCP-B/C dimers and FCP-A tetramers) that coexist in the marine centric diatom using both time-resolved fluorescence and transient absorption spectroscopy. We found that the FCP-B/C complex did not show fluorescence quenching, whereas FCP-A was severely quenched, via an ultrafast excitation energy transfer (EET) pathway from Chl a Q to the fucoxanthin S/ICT state. These results highlight the functional differences between FCP dimers and tetramers and indicate that the EET pathway from Chl a to carotenoids is an energy dissipation mechanism conserved in a variety of photosynthetic organisms.
褐藻黄素-叶绿素蛋白（FCPs）是一类存在于硅藻中的光合光捕获复合物（LHC）蛋白。它们能够高效地捕获光子并调节其功能，确保硅藻在高度波动的光环境中存活。FCPs 以不同的寡聚状态存在，但这些 FCP 寡聚体之间的功能差异尚未完全阐明。本研究使用时间分辨荧光和瞬态吸收光谱技术，对海洋中心硅藻中存在的两种天线复合物（FCP-B/C 二聚体和 FCP-A 四聚体）进行了表征。研究发现，FCP-B/C 复合物没有发生荧光猝灭，而 FCP-A 则通过超快的激发能量转移（EET）途径从 Chl a Q 到褐藻黄素 S/ICT 态被严重猝灭。这些结果突出了 FCP 二聚体和四聚体之间的功能差异，并表明从 Chl a 到类胡萝卜素的 EET 途径是一种在各种光合生物中保守的能量耗散机制。
