6dhh
From Proteopedia
RT XFEL structure of Photosystem II 400 microseconds after the second illumination at 2.2 Angstrom resolution
Structural highlights
Function[PSBL_THEEB] Required for PSII activity (By similarity). [YCF12_THEEB] A core subunit of photosystem II (PSII).[HAMAP-Rule:MF_01329] [PSBB_THEEB] One of the components of the core complex of photosystem II (PSII). It binds chlorophyll and helps catalyze the primary light-induced photochemical processes of PSII. PSII is a light-driven water:plastoquinone oxidoreductase, using light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation.[HAMAP-Rule:MF_01495][1] [2] [3] [PSBA1_THEEB] This is one of the two reaction center proteins of photosystem II. [PSBX_THEEB] Involved in the binding and/or turnover of quinones at the Q(B) site of Photosystem II.[4] [CY550_THEEB] Low-potential cytochrome c that plays a role in the oxygen-evolving complex of photosystem II. It is not essential for growth under normal conditions but is required under low CO(2) concentrations.[HAMAP-Rule:MF_01378] [PSBO_THEEB] MSP binds to a putative Mn-binding protein and keeps 2 of the 4 Mn-atoms associated with PSII (By similarity). [PSBF_THEEB] This b-type cytochrome is tightly associated with the reaction center of photosystem II and possibly is part of the water-oxidation complex (By similarity).[HAMAP-Rule:MF_00643] [PSBC_THEEB] One of the components of the core complex of photosystem II (PSII). It binds chlorophyll and helps catalyze the primary light-induced photochemical processes of PSII. PSII is a light-driven water:plastoquinone oxidoreductase, using light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation.[HAMAP-Rule:MF_01496][5] [6] [7] [PSBJ_THEEB] This protein is a component of the reaction center of photosystem II (By similarity). [PSBT_THEEB] Seems to play a role in the dimerization of PSII.[8] [PSBU_THEEB] Stabilizes the structure of photosystem II oxygen-evolving complex (OEC), the ion environment of oxygen evolution and protects the OEC against heat-induced inactivation (By similarity).[HAMAP-Rule:MF_00589] [PSBI_THEEB] This protein is a component of the reaction center of photosystem II.[HAMAP-Rule:MF_01316] [PSBZ_THEEB] Controls the interaction of photosystem II (PSII) cores with the light-harvesting antenna. May also aid in binding of PsbK, Ycf12 and the oxygen-evolving complex to PSII, at least in vitro.[9] [PSBK_THEEB] This protein is a component of the reaction center of photosystem II.[HAMAP-Rule:MF_00441] [PSBE_THEEB] This b-type cytochrome is tightly associated with the reaction center of photosystem II and possibly is part of the water-oxidation complex.[HAMAP-Rule:MF_00642] Publication Abstract from PubMedInspired by the period-four oscillation in flash-induced oxygen evolution of photosystem II discovered by Joliot in 1969, Kok performed additional experiments and proposed a five-state kinetic model for photosynthetic oxygen evolution, known as Kok's S-state clock or cycle(1,2). The model comprises four (meta)stable intermediates (S0, S1, S2 and S3) and one transient S4 state, which precedes dioxygen formation occurring in a concerted reaction from two water-derived oxygens bound at an oxo-bridged tetra manganese calcium (Mn4CaO5) cluster in the oxygen-evolving complex(3-7). This reaction is coupled to the two-step reduction and protonation of the mobile plastoquinone QB at the acceptor side of PSII. Here, using serial femtosecond X-ray crystallography and simultaneous X-ray emission spectroscopy with multi-flash visible laser excitation at room temperature, we visualize all (meta)stable states of Kok's cycle as high-resolution structures (2.04-2.08 A). In addition, we report structures of two transient states at 150 and 400 micros, revealing notable structural changes including the binding of one additional 'water', Ox, during the S2-->S3 state transition. Our results suggest that one water ligand to calcium (W3) is directly involved in substrate delivery. The binding of the additional oxygen Ox in the S3 state between Ca and Mn1 supports O-O bond formation mechanisms involving O5 as one substrate, where Ox is either the other substrate oxygen or is perfectly positioned to refill the O5 position during O2 release. Thus, our results exclude peroxo-bond formation in the S3 state, and the nucleophilic attack of W3 onto W2 is unlikely. Structures of the intermediates of Kok's photosynthetic water oxidation clock.,Kern J, Chatterjee R, Young ID, Fuller FD, Lassalle L, Ibrahim M, Gul S, Fransson T, Brewster AS, Alonso-Mori R, Hussein R, Zhang M, Douthit L, de Lichtenberg C, Cheah MH, Shevela D, Wersig J, Seuffert I, Sokaras D, Pastor E, Weninger C, Kroll T, Sierra RG, Aller P, Butryn A, Orville AM, Liang M, Batyuk A, Koglin JE, Carbajo S, Boutet S, Moriarty NW, Holton JM, Dobbek H, Adams PD, Bergmann U, Sauter NK, Zouni A, Messinger J, Yano J, Yachandra VK Nature. 2018 Nov;563(7731):421-425. doi: 10.1038/s41586-018-0681-2. Epub 2018 Nov, 7. PMID:30405241[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Large Structures | Photosystem II | Thermosynechococcus elongatus | Thermosynechococcus elongatus bp-1 | Adams, P D | Aller, P | Alonso-Mori, R | Batyuk, A | Bergmann, U | Boutet, S | Brewster, A S | Butryn, A | Carbajo, S | Chatterjee, R | Cheah, M H | Dobbek, H | Douthit, L | Fransson, T | Fuller, F D | Gul, S | Holton, J M | Hussein, R | Ibrahim, M | Kern, J | Koglin, J E | Kroll, T | Lassalle, L | Liang, M | Lichtenberg, C de | Messinger, J | Moriarty, N W | Orville, A M | Pastor, E | Sauter, N K | Seufert, I | Shevela, D | Sierra, R G | Sokaras, D | Weninger, C | Wersig, J | Yachandra, V K | Yano, J | Young, I D | Zhang, M | Zouni, A | Electron transport | Photosynthesis | Photosystem | Room temperature | Transmembrane
