ジャーナル: Nature / 年: 2020 タイトル: Structural basis of energy transfer in Porphyridium purpureum phycobilisome. 著者: Jianfei Ma / Xin You / Shan Sun / Xiaoxiao Wang / Song Qin / Sen-Fang Sui / 要旨: Photosynthetic organisms have developed various light-harvesting systems to adapt to their environments. Phycobilisomes are large light-harvesting protein complexes found in cyanobacteria and red ...Photosynthetic organisms have developed various light-harvesting systems to adapt to their environments. Phycobilisomes are large light-harvesting protein complexes found in cyanobacteria and red algae, 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 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.
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THIS DEPOSITION 7LIX PROVIDES A STRUCTURAL MODEL FOR PREVIOUSLY UNMODELED EM MAP DENSITY IN EMD- ...THIS DEPOSITION 7LIX PROVIDES A STRUCTURAL MODEL FOR PREVIOUSLY UNMODELED EM MAP DENSITY IN EMD-9976. THIS IS NOT A REPLACEMENT, ONLY AN ADDITION. ORIGINAL AUTHORS OF EMD-9976 ARE SUI, S.F., MA, J.F., YOU, X., SUN, S.