9unu

PSI-1 FCPI supercomplex from haptophyte Chrysotila roscoffensis

spinqualitylabelsall models 9unu, resolution 2.18Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9unu is a 10 chain structure with sequence from Chrysotila roscoffensis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.18Å Ligands: A86, BCR, CLA, DD6, DGD, KC1, LHG, LMG, PQN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Photosystem I (PSI) converts light energy into chemical energy in photosynthesis, and forms supercomplexes with light-harvesting complexes (LHCI) in eukaryotes to enhance energy capture and transfer. Various numbers and organizations of both PSI core and LHCI subunits are observed in various organisms. A subgroup of haptophytes named coccolithophores play a major role in marine carbon cycle and CaCO(3) production, and the light-harvesting antennas of them are named FCPs (fucoxanthin-chlorophyll a/c binding protein) because they bind chlorophyll c and fucoxanthin in addition to chlorophyll a. A structure of a large PSI-FCPI supercomplex containing 38 FCPI subunits has been reported from a coccolithophore Emiliania huxleyi recently (L. Shen et al., Science 389, eadv2132, 2025). Here we solved five cryo-electron microscopy (cryo-EM) structures of PSI-FCPI supercomplexes isolated from another coccolithophore Chrysotila roscoffensis with different detergents at resolutions ranging from 2.3 to 1.7 A. These structures represent discrete PSI-FCPIs containing 1, 4, 6, 8 and 9 FCPI subunits, with FCPIs arranged in a modular fashion. Association of each FCPI module to the PSI core, as well as the arrangement of protein subunits and pigments, are revealed. Contributions of individual antenna modules to excitation energy transfer were calculated and compared with PSI-FCPI supercomplexes from other species of coccolithophores and haptophytes. These results pinpoint the assembly of stable PSI-FCPI supercomplexes in C. roscoffensis and provide insights into how antenna modules contribute to energy transfer in coccolithophores. Multiple structures of photosystem I-FCPI supercomplexes from a coccolithophore alga reveal a modular antenna organization.,La Rocca R, Tsai PC, Kato K, Nakajima Y, Akita F, Shen JR Biochim Biophys Acta Bioenerg. 2026 Mar 19;1867(3):149588. doi: , 10.1016/j.bbabio.2026.149588. PMID:41864554 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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