Control Mechanism of Excitation Energy Transfer in a Complex Consisting of Photosystem II and Fucoxanthin Chlorophyll a/c-Binding Protein
Control Mechanism of Excitation Energy Transfer in a Complex Consisting of Photosystem II and Fucoxanthin Chlorophyll a/c-Binding Protein
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DOI：
10.1021/jz501496p
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发表时间：
2014-09-04
影响因子：
5.7
通讯作者：
Akimoto, Seiji
中科院分区：
文献类型：
--
作者：
Nagao, Ryo;Yokono, Makio;Akimoto, Seiji
岩藻黄素叶绿素（Chi）a/c结合蛋白（FCP）是硅藻中独特的捕光天线，硅藻是广泛存在于水生环境中的光合藻类。然而，它是未知的激发能是如何被捕获和淬灭的复合物组成的光系统II和FCP（PSII FCPII复合物）。在这里，我们报告的PSII-FCPII复合物中分离的硅藻，角毛藻纤细，皮秒时间分辨荧光光谱所揭示的激发能量转移的控制机制。结果表明，在77 K条件下，叶绿素激发能主要集中在FCPII附近或内部的低能叶绿素中，而在283 K条件下，大部分能量集中在PSII的反应中心叶绿素中。令人惊讶的是，在PSII-FCPII复合物的一部分中观察到激发能猝灭，其时间常数为数百皮秒，从而表明FCPII对能量捕获和猝灭的贡献很大。在此基础上，讨论了硅藻的捕光策略。
Fucoxanthin chlorophyll (Chi) a/c-binding protein (FCP) is a unique light-harvesting antenna in diatoms, which are photosynthesizing algae ubiquitous in aquatic environments. However, it is unknown how excitation energy is trapped and quenched in a complex consisting of photosystem II and FCP (PSII FCPII complex). Here, we report the control mechanism of excitation energy transfer in the PSII-FCPII complexes isolated from a diatom, Chaetoceros gracilis, as revealed by picosecond time-resolved fluorescence spectroscopy. The results showed that Chl-excitation energy is harvested in low-energy Chls near/within FCPII under the 77 K conditions, whereas most of the energy is trapped in reaction center Chls in PSII under the 283 K conditions. Surprisingly, excitation energy quenching was observed in a part of PSII-FCPII complexes with the time constants of hundreds of picosecond, thus indicating the large contribution of FCPII to energy trapping and quenching. On the basis of these results, we discuss the light-harvesting strategy of diatoms.