6j3z
From Proteopedia
Structure of C2S1M1-type PSII-FCPII supercomplex from diatom
Structural highlights
Function[B7XBY7_9STRA] One of the components of the core complex of photosystem II (PSII), required for its stability and/or assembly. PSII is a light-driven water:plastoquinone oxidoreductase that uses light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation. It consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation.[HAMAP-Rule:MF_00752] [B6ZHF2_9STRA] Involved in the binding and/or turnover of quinones at the Q(B) site of Photosystem II.[HAMAP-Rule:MF_01386] [B6ZHF4_9STRA] Low-potential cytochrome c that plays a role in the oxygen-evolving complex of photosystem II.[HAMAP-Rule:MF_01378] Publication Abstract from PubMedLight-harvesting antenna systems in photosynthetic organisms harvest solar energy and transfer it to the photosynthetic reaction centres to initiate charge-separation and electron-transfer reactions. Diatoms are one of the important groups of oxyphototrophs and possess fucoxanthin chlorophyll a/c-binding proteins (FCPs) as light harvesters. The organization and association pattern of FCP with the photosystem II (PSII) core are unknown. Here we solved the structure of PSII-FCPII supercomplexes isolated from a diatom, Chaetoceros gracilis, by single-particle cryoelectron microscopy. The PSII-FCPII forms a homodimer. In each monomer, two FCP homotetramers and three FCP monomers are associated with one PSII core. The structure reveals a highly complicated protein-pigment network that is different from the green-type light-harvesting apparatus. Comparing these two systems allows the identification of energy transfer and quenching pathways. These findings provide structural insights into not only excitation-energy transfer mechanisms in the diatom PSII-FCPII, but also changes of light harvesters between the red- and green-lineage oxyphototrophs during evolution. Structural basis for energy harvesting and dissipation in a diatom PSII-FCPII supercomplex.,Nagao R, Kato K, Suzuki T, Ifuku K, Uchiyama I, Kashino Y, Dohmae N, Akimoto S, Shen JR, Miyazaki N, Akita F Nat Plants. 2019 Aug;5(8):890-901. doi: 10.1038/s41477-019-0477-x. Epub 2019 Jul , 29. PMID:31358960[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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