13ch | pdb_000013ch
RT XFEL structure of one-flash state of Photosystem II (1F, S2 rich) at 2.02 Angstrom
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 PubMedWater oxidation in photosynthesis occurs through a four-electron redox reaction that is catalyzed by the oxygen-evolving complex (OEC) in Photosystem II (PS II), that consists of the Mn(4)CaO(5) cluster. Among the four stable intermediates in the water oxidation reaction, it has been reported that the paramagnetic S(2) state with the formal oxidation of Mn(III)Mn(IV)(3) has multiple spin states, that include high spin (HS, 5/2, g>/=4.1) and low spin (LS, 1/2, gâ¯=â¯2) forms. Previous computational studies proposed that these two forms differ in their structure and the high spin form may represent an intermediate form of the OEC during the S(2) to S(3) transition, the step in which the first substrate water binds to the last open coordination site of the cluster. In the current study, we examined the pH-induced HS-S(2) state of T. vestitus PS II with MnK edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge spectroscopy (XANES). Small, but notable differences were observed in the EXAFS and XANES between the HS and LS S(2) states. EXAFS data and the fits indicate that the basic geometry of the cluster remains the same between these two states. Therefore, we hypothesize that the difference between the HS and LS S(2) state may be due to chemical differences such as different protonation states of the oxo and/or water ligands, or its surroundings. We also examined the detailed oxygen positions of the S(2) states in the XFEL-based room temperature crystal structures, and confirmed that at neutral pH at room temperature, the structure is consistent with that of the LS-S(2) model with open cubane-like geometry. Investigation of the high-spin S(2) states in photosystem II using Mn X-ray absorption spectroscopy with insights from XFEL crystallography.,Bogacz I, Chatterjee R, Zhang M, Bhowmick A, Kern J, Yachandra VK, Yano J Biochim Biophys Acta Bioenerg. 2026 Sep 10:149608. doi: , 10.1016/j.bbabio.2026.149608. PMID:42722122[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
| ||||||||||||||||||||
