The organization of the phycobilisome-photosystem I supercomplex depends on the ratio between two different phycobilisome linker proteins
The organization of the phycobilisome-photosystem I supercomplex depends on the ratio between two different phycobilisome linker proteins
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DOI：
10.1007/s43630-023-00397-2
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发表时间：
2023-03
影响因子：
3.1
通讯作者：
Mai Watanabe;M. Ikeuchi;A. Wilde
中科院分区：
文献类型：
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作者：
Mai Watanabe;M. Ikeuchi;A. Wilde
藻胆体（phycobilisome，PBS）是蓝藻、蓝囊藻和红藻中的一种触角蛋白复合体。在标准PBS中，即杆-核PBS中，杆通过杆-核接头蛋白CpcG连接到核。棒芯PBS主要将光能传递到光系统（PS）II，并在较小程度上传递到PSI。蓝细菌组装另一种类型的PBS，CpcL-PBS，它只由一个杆组成。这种杆状PBS通过连接蛋白CpcL连接到类囊体膜，是PSI特异性天线。在丝状异型囊形成蓝藻Anabaena（Nostoc）sp.在PCC 7120中，CpcL-PBS与四聚体PSI形成复合物（PBS-PSI超复合物）。除了接头蛋白CpcL和CpcG之外，CpcL-PBS和棒-核PBS的棒部分是相同的。细胞如何控制两种不同类型PBS的积累尚不清楚。在这里，我们分析了两个突变株，要么缺乏主要的杆-核心接头CpcG 4或过表达的杆-膜接头CpcL。在两种突变株中，与野生型相比，积累了更多和更大的PBS-PSI超复合物。我们的研究结果表明，CpcL和CpcG 4竞争相同的藻胆蛋白池，因此CpcL/CpcG 4的比例决定PBS-PSI超复合物的水平。我们认为CpcL-PBS和棒芯PBS在光捕获方面实现了不同的功能。图形摘要
The phycobilisome (PBS) is an antenna protein complex in cyanobacteria, Glaucocystophytes, and red algae. In the standard PBS, the rod-core PBS, the rods are connected to the core by the rod-core linker protein CpcG. The rod-core PBS transfers the light energy mainly to photosystem (PS) II and to a lesser extent to PSI. Cyanobacteria assemble another type of PBS, the CpcL-PBS, which consists of only one rod. This rod-type PBS is connected to the thylakoid membrane by the linker protein CpcL and is a PSI-specific antenna. In the filamentous heterocyst-forming cyanobacteriumAnabaena(Nostoc) sp. PCC 7120, the CpcL-PBS forms a complex with the tetrameric PSI (PBS-PSI supercomplex). The CpcL-PBS and the rod part of the rod-core PBS are identical except for the linker proteins CpcL and CpcG. How cells control the accumulation of the two different types of PBS is unknown. Here, we analyzed two mutant strains which either lack the major rod-core linker CpcG4 or overexpress the rod-membrane linker CpcL. In both mutant strains, more and larger PBS-PSI supercomplexes accumulated compared to the wild type. Our results suggest that CpcL and CpcG4 compete for the same phycobiliprotein pool, and therefore the CpcL/CpcG4 ratio determines the levels of PBS-PSI supercomplexes. We propose that the CpcL-PBS and the rod-core PBS fulfill distinct functions in light harvesting.Graphical abstract