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Organization and energy transfer in a huge diatom PSI-FCPI supercomplex
Structural highlights
FunctionA0A6J4B150_9STRA The light-harvesting complex (LHC) functions as a light receptor, it captures and delivers excitation energy to photosystems with which it is closely associated. Energy is transferred from the carotenoid and chlorophyll C (or B) to chlorophyll A and the photosynthetic reaction centers where it is used to synthesize ATP and reducing power.[ARBA:ARBA00004022] Publication Abstract from PubMedDiatom is an important group of marine algae and contributes to around 20% of the global photosynthetic carbon fixation. Photosystem I (PSI) of diatoms is associated with a large number of fucoxanthin-chlorophyll a/c proteins (FCPIs). We report the structure of PSI-FCPI from a diatom Chaetoceros gracilis at 2.38 A resolution by single-particle cryo-electron microscopy. PSI-FCPI is a monomeric supercomplex consisting of 12 core and 24 antenna subunits (FCPIs), and 326 chlorophylls a, 34 chlorophylls c, 102 fucoxanthins, 35 diadinoxanthins, 18 beta-carotenes and some electron transfer cofactors. Two subunits designated PsaR and PsaS were found in the core, whereas several subunits were lost. The large number of pigments constitute a unique and huge network ensuring efficient energy harvesting, transfer and dissipation. These results provide a firm structural basis for unraveling the mechanisms of light-energy harvesting, transfer and quenching in the diatom PSI-FCPI, and also important clues to evolutionary changes of PSI-LHCI. Structural basis for energy transfer in a huge diatom PSI-FCPI supercomplex.,Xu C, Pi X, Huang Y, Han G, Chen X, Qin X, Huang G, Zhao S, Yang Y, Kuang T, Wang W, Sui SF, Shen JR Nat Commun. 2020 Oct 8;11(1):5081. doi: 10.1038/s41467-020-18867-x. PMID:33033236[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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