9i9l

Structure of Far-Red Photosystem I from C. thermalis PCC 7203

spinqualitylabelsall models 9i9l, resolution 1.89Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9i9l is a 30 chain structure with sequence from Chroococcidiopsis thermalis PCC 7203. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 1.89Å Ligands: BCR, CA, CLA, F6C, LFA, LHG, LMG, LMT, PQN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function K9TWJ0_CHRTP PsaA and PsaB bind P700, the primary electron donor of photosystem I (PSI), as well as the electron acceptors A0, A1 and FX. PSI is a plastocyanin/cytochrome c6-ferredoxin oxidoreductase, converting photonic excitation into a charge separation, which transfers an electron from the donor P700 chlorophyll pair to the spectroscopically characterized acceptors A0, A1, FX, FA and FB in turn. Oxidized P700 is reduced on the lumenal side of the thylakoid membrane by plastocyanin or cytochrome c6.[ARBA:ARBA00002612][HAMAP-Rule:MF_00458] PsaA and psaB bind P700, the primary electron donor of photosystem I (PSI), as well as the electron acceptors A0, A1 and FX.[RuleBase:RU003775] Publication Abstract from PubMed The discovery of chlorophyll f-containing photosystems, with their long-wavelength photochemistry, represented a distinct, low-energy paradigm for oxygenic photosynthesis. Structural studies on chlorophyll f-containing photosystem I could identify some chlorophylls f sites, but none among the photochemically active pigments and concluded that chlorophyll f plays no photochemical role. Here, we report two cryo-EM structures of far-red PSI from Chroococcidiopsis thermalis PCC 7203, allowing the assignment of eight chlorophylls f molecules, including the redox active A(-1B). Simulations of absorption difference spectra induced by charge separation indicate that the experimental spectra can be reproduced only by considering the presence of a chlorophyll f at the A(-1B) site. The chlorophyll f locations, wavelength assignments, and conserved far-red-specific residues provide functional insights for efficient use of long wavelength photons. Locating the missing chlorophylls f in far-red photosystem I.,Consoli G, Tufail F, Leong HF, Viola S, Davis GA, Rew N, Medranda D, Hofer M, Simpson P, Sandrin M, Chachuat B, Nelson J, Renger T, Murray JW, Fantuzzi A, Rutherford AW Science. 2025 Oct 9:eado6830. doi: 10.1126/science.ado6830. PMID:41066538 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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