Structural organization of an intact phycobilisome and its association with photosystem II
Structural organization of an intact phycobilisome and its association with photosystem II
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完整藻胆体的结构组织及其与光系统 II 的关联
DOI：
10.1038/cr.2015.59
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发表时间：
2015-06-01
期刊：
影响因子：
44.1
通讯作者：
Sui, Sen-Fang
中科院分区：
文献类型：
--
作者：
Chang, Leifu;Liu, Xianwei;Sui, Sen-Fang
藻胆体 (PBS) 是一种光捕获天线，可将能量转移到蓝细菌和红藻的光合作用反应中心。 PBS 是由藻胆蛋白 (PBP) 组成的超分子复合物，其带有用于能量吸收的发色团和连接蛋白。尽管已经使用晶体学确定了一些单独成分的结构，但对于理解能量转移机制至关重要的整个 PBS 复合物的三维结构仍然未知。在这里，我们报告了完整 PBS 和鱼腥藻光系统 II (PSII) 复合物的 PBS 的结构。使用单颗粒电子显微镜结合生化和分子分析对 PCC 7120 菌株进行分析。在 PBS 结构中，所有 PBP 三聚体和保守的接头蛋白结构域均被明确定位，并确定了所有发色团的全局分布。我们提供的证据表明，ApcE 和 ApcF 对于 PBS 底部突起的形成至关重要，这在介导 PBS 与 PSII 相互作用中发挥着重要作用。我们的结果提供了对完整 PBS 在不同组装水平的分子结构的见解，并为理解 PBS 吸收的光能如何转移到 PSII 提供了基础。
Phycobilisomes (PBSs) are light-harvesting antennae that transfer energy to photosynthetic reaction centers in cyanobacteria and red algae. PBSs are supermolecular complexes composed of phycobiliproteins (PBPs) that bear chromophores for energy absorption and linker proteins. Although the structures of some individual components have been determined using crystallography, the three-dimensional structure of an entire PBS complex, which is critical for understanding the energy transfer mechanism, remains unknown. Here, we report the structures of an intact PBS and a PBS in complex with photosystem II (PSII) from Anabaena sp. strain PCC 7120 using single-particle electron microscopy in combination with biochemical and molecular analyses. In the PBS structure, all PBP trimers and the conserved linker protein domains were unambiguously located, and the global distribution of all chromophores was determined. We provide evidence that ApcE and ApcF are critical for the formation of a protrusion at the bottom of PBS, which plays an important role in mediating PBS interaction with PSII. Our results provide insights into the molecular architecture of an intact PBS at different assembly levels and provide the basis for understanding how the light energy absorbed by PBS is transferred to PSII.