8f4f
From Proteopedia
RT XFEL structure of Photosystem II 500 microseconds after the third illumination at 2.03 Angstrom resolution
Structural highlights
FunctionPSBA1_THEVB 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.[HAMAP-Rule:MF_01379][1] [2] [3] Publication Abstract from PubMedIn natural photosynthesis, the light-driven splitting of water into electrons, protons and molecular oxygen forms the first step of the solar-to-chemical energy conversion process. The reaction takes place in photosystem II, where the Mn(4)CaO(5) cluster first stores four oxidizing equivalents, the S(0) to S(4) intermediate states in the Kok cycle, sequentially generated by photochemical charge separations in the reaction center and then catalyzes the O-O bond formation chemistry(1-3). Here, we report room temperature snapshots by serial femtosecond X-ray crystallography to provide structural insights into the final reaction step of Kok's photosynthetic water oxidation cycle, the S(3)-->[S(4)]-->S(0) transition where O(2) is formed and Kok's water oxidation clock is reset. Our data reveal a complex sequence of events, which occur over micro- to milliseconds, comprising changes at the Mn(4)CaO(5) cluster, its ligands and water pathways as well as controlled proton release through the hydrogen-bonding network of the Cl1 channel. Importantly, the extra O atom O(x), which was introduced as a bridging ligand between Ca and Mn1 during the S(2)-->S(3) transition(4-6), disappears or relocates in parallel with Y(z) reduction starting at approximately 700 mus after the third flash. The onset of O(2) evolution, as indicated by the shortening of the Mn1-Mn4 distance, occurs at around 1,200 mus, signifying the presence of a reduced intermediate, possibly a bound peroxide. Structural evidence for intermediates during O(2) formation in photosystem II.,Bhowmick A, Hussein R, Bogacz I, Simon PS, Ibrahim M, Chatterjee R, Doyle MD, Cheah MH, Fransson T, Chernev P, Kim IS, Makita H, Dasgupta M, Kaminsky CJ, Zhang M, Gatcke J, Haupt S, Nangca II, Keable SM, Aydin AO, Tono K, Owada S, Gee LB, Fuller FD, Batyuk A, Alonso-Mori R, Holton JM, Paley DW, Moriarty NW, Mamedov F, Adams PD, Brewster AS, Dobbek H, Sauter NK, Bergmann U, Zouni A, Messinger J, Kern J, Yano J, Yachandra VK Nature. 2023 May;617(7961):629-636. doi: 10.1038/s41586-023-06038-z. Epub 2023 , May 3. PMID:37138085[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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Categories: Large Structures | Thermosynechococcus vestitus BP-1 | Adams PD | Alonso-Mori R | Aydin O | Batyuk A | Bergmann U | Bhowmick A | Bogacz I | Brewster AS | Chatterjee R | Cheah MH | Chernev P | Dasgupta M | Dobbek H | Doyle MD | Fransson T | Fuller FD | Gatcke J | Gee LB | Haupt S | Holton JM | Hussein R | Ibrahim M | Kaminsky CJ | Keable SM | Kern J | Kim I-S | Makita H | Mamedov F | Messinger J | Moriarty NW | Nangca II | Owada S | Paley DW | Sauter NK | Simon PS | Tono K | Yachandra VK | Yano J | Zhang M | Zouni A
