Direct Energy Transfer from Allophycocyanin-Free Rod-Type CpcL-Phycobilisome to Photosystem I
Direct Energy Transfer from Allophycocyanin-Free Rod-Type CpcL-Phycobilisome to Photosystem I
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DOI：
10.1021/acs.jpclett.1c01763
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发表时间：
2021-07-14
影响因子：
5.7
通讯作者：
Ikeuchi, Masahiko
中科院分区：
文献类型：
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作者：
Noji, Tomoyasu;Watanabe, Mai;Ikeuchi, Masahiko
藻胆体（Phycobilisomes，PBS）是由连接蛋白连接的色素结合蛋白（核和杆）组成的光合天线巨复合体。不具有核心的杆状PBS通过CpcL连接蛋白连接到光系统I（PSI），CpcL连接蛋白稳定杆状物中的藻蓝胆素的红色形式（红色PCB）。然而，尚未确定从红色型PBS到PSI的能量转移的定量信息。在此，分离的超复合物的杆型PBS和PSI四聚体从鱼腥藻属PCC 7120的探测在77 K下的时间分辨光谱和衰变相关的光谱分析表明，红色PCB介导的快速和有效的（时间常数= 90 ps，效率= 95%）的激发能从PCB叶绿素a（Chla）的转移。根据Forster能量转移机制，这种高效率对应于红色PCB和Chl a之间的4 nm距离，表明杆中的β-84 PCB充当红色PCB。
Phycobilisomes (PBSs) are photosynthetic antenna megacomplexes comprising pigment-binding proteins (cores and rods) joined with linker proteins. A rod-type PBS that does not have a core is connected to photosystem I (PSI) by a CpcL linker protein, which stabilizes a red-form of the phycocyanobilin (red-PCB) in the rod. However, quantitative information on the energy transfer from red-type PBS to PSI has not been determined. Herein, the isolated supercomplex of the rod-type PBS and the PSI tetramer from Anabaena sp. PCC 7120 were probed by time-resolved spectroscopy at 77 K and by decay-associated spectral analysis to show that red-PCB mediates the fast and efficient (time constant = 90 ps, efficiency = 95%) transfer of excitation energy from PCB to chlorophyll a (Chl a). According to the Forster energy transfer mechanism, this high efficiency corresponds to a 4 nm distance between red-PCB and Chl a, suggesting that beta-84 PCB in the rod acts as red-PCB.