8eqm

Structure of a dimeric photosystem II complex acclimated to far-red lightStructure of a dimeric photosystem II complex acclimated to far-red light

Structural highlights 8eqm is a 20 chain structure with sequence from Synechococcus sp. PCC 7335. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.6Å Ligands: , , , , , , , , , , , , , , Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function B4WKH9_SYNS7 Photosystem II (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. The D1/D2 (PsbA/PsbD) reaction center heterodimer binds P680, the primary electron donor of PSII as well as several subsequent electron acceptors.[ARBA:ARBA00037683] Publication Abstract from PubMed Photosystem II (PSII) is the water-splitting enzyme central to oxygenic photosynthesis. To drive water oxidation, light is harvested by accessory pigments, mostly chlorophyll (Chl) a molecules, which absorb visible light (400-700 nm). Some cyanobacteria facultatively acclimate to shaded environments by altering their photosynthetic machinery to additionally absorb far-red light (FRL, 700-800 nm), a process termed far-red light photoacclimation or FaRLiP. During far-red light photoacclimation, FRL-PSII is assembled with FRL-specific isoforms of the subunits PsbA, PsbB, PsbC, PsbD, and PsbH, and some Chl-binding sites contain Chls d or f instead of the usual Chl a. The structure of an apo-FRL-PSII monomer lacking the FRL-specific PsbH subunit has previously been determined, but visualization of the dimeric complex has remained elusive. Here, we report the cryo-EM structure of a dimeric FRL-PSII complex. The site assignments for Chls d and f are consistent with those assigned in the previous apo-FRL-PSII monomeric structure. All sites that bind Chl d or Chl f at high occupancy exhibit a FRL-specific interaction of the formyl moiety of the Chl d or Chl f with the protein environment, which in some cases involves a phenylalanine sidechain. The structure retains the FRL-specific PsbH2 subunit, which appears to alter the energetic landscape of FRL-PSII, redirecting energy transfer from the phycobiliprotein complex to a Chl f molecule bound by PsbB2 that acts as a bridge for energy transfer to the electron transfer chain. Collectively, these observations extend our previous understanding of the structure-function relationship that allows PSII to function using lower energy FRL. Structure of a dimeric photosystem II complex from a cyanobacterium acclimated to far-red light.,Gisriel CJ, Shen G, Flesher DA, Kurashov V, Golbeck JH, Brudvig GW, Amin M, Bryant DA J Biol Chem. 2023 Jan;299(1):102815. doi: 10.1016/j.jbc.2022.102815. Epub 2022 , Dec 20. PMID:36549647 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Photosystem II 3D structures

spinqualitylabelsall models 8eqm, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image