Structural basis of energy transfer in Porphyridium purpureum phycobilisome
Structural basis of energy transfer in Porphyridium purpureum phycobilisome
复制标题
紫球藻藻胆体能量转移的结构基础
DOI：
10.1038/s41586-020-2020-7
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发表时间：
2020-02-19
期刊：
影响因子：
64.8
通讯作者：
Sui, Sen-Fang
中科院分区：
文献类型：
--
作者：
Ma, Jianfei;You, Xin;Sui, Sen-Fang
来自红藻紫球藻的藻胆体的冷冻电子显微镜结构揭示了连接蛋白和生色团之间的芳香族相互作用如何驱动能量的单向转移。光合成生物已经开发出各种捕光系统来适应他们的环境[1]。藻胆体是在蓝藻和红藻(2-4)中发现的大型捕光蛋白质复合体，尽管这些复合体中生色团的能量如何受到环境的调节尚不清楚。在这里，我们报道了来自红藻紫球藻的一个14.7百万吨的半椭圆形藻胆体的冷冻电子显微镜结构。在这个复合体中，我们确定了706个蛋白质亚基的结构，包括528个藻红蛋白、72个藻蓝蛋白、46个别藻蓝蛋白和60个连接蛋白。此外，还分离了1,598个发色团，包括1,430个藻红胆素分子、48个藻蓝胆素分子和120个藻蓝胆素分子。与太平洋格里菲斯藻胆体相比，我们的结构分辨率显著提高(5)，这使我们能够建立紫锥藻藻胆体系统的准确原子模型。该模型揭示了连接蛋白如何影响生色团的微环境，并表明连接蛋白的芳香族氨基酸与生色团的相互作用可能是微调生色团的能量状态以确保能量的有效单向转移的关键因素。
The cryo-electron microscopy structure of a phycobilisome from the red alga Porphyridium purpureum reveals how aromatic interactions between the linker proteins and the chromophores drive a unidirectional transfer of energy.Photosynthetic organisms have developed various light-harvesting systems to adapt to their environments(1). Phycobilisomes are large light-harvesting protein complexes found in cyanobacteria and red algae(2-4), although how the energies of the chromophores within these complexes are modulated by their environment is unclear. Here we report the cryo-electron microscopy structure of a 14.7-megadalton phycobilisome with a hemiellipsoidal shape from the red alga Porphyridium purpureum. Within this complex we determine the structures of 706 protein subunits, including 528 phycoerythrin, 72 phycocyanin, 46 allophycocyanin and 60 linker proteins. In addition, 1,598 chromophores are resolved comprising 1,430 phycoerythrobilin, 48 phycourobilin and 120 phycocyanobilin molecules. The markedly improved resolution of our structure compared with that of the phycobilisome of Griffithsia pacifica(5) enabled us to build an accurate atomic model of the P. purpureum phycobilisome system. The model reveals how the linker proteins affect the microenvironment of the chromophores, and suggests that interactions of the aromatic amino acids of the linker proteins with the chromophores may be a key factor in fine-tuning the energy states of the chromophores to ensure the efficient unidirectional transfer of energy.