start-ver=1.4 cd-journal=joma no-vol=16 cd-vols= no-issue=26 article-no= start-page=12024 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=2025 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Collective motions in the primary coordination sphere: a critical functional framework for catalytic activity of the oxygen-evolving complex of photosystem II en-subtitle= kn-subtitle= en-abstract= kn-abstract=Photosynthetic water oxidation, vital for dioxygen production and light energy conversion, is catalyzed by the oxygen-evolving complex of photosystem II, where the inorganic Mn4CaO5 cluster acts as the catalytic core. In this study, we investigate the functional significance of collective motions of amino acid side chains within the primary coordination sphere of the Mn cluster, focusing on their role in modulating the energetic demands for catalytic transformations in the S3 state. We applied regularized canonical correlation analysis to quantitatively correlate the three-dimensional arrangement of coordinating atoms with catalytic driving forces computed via density functional theory. Our analysis reveals that distinct collective side chain motions profoundly influence the energetic requirements for structural reconfigurations of the Mn cluster, achieved through expansion and contraction of the ligand cavity while fine-tuning its geometry to stabilize key intermediates. Complementary predictions from a neural network-based machine learning model indicate that the coordination sphere exerts a variable energetic impact on the catalytic transformations of the Mn cluster, depending on the S-state environment. Integrated computational analyses suggest that the extended lifetime of the S3YZ˙ state, consistently observed after three flash illuminations, may result from slow, progressive protein dynamics that continuously reshape the energy landscape, thereby shifting the equilibrium positions of rapid, reversible chemical processes over time. Overall, our findings demonstrate that collective motions in the primary coordination sphere constitute an active, dynamic framework essential for the efficient execution of multi-electron catalysis under ambient conditions, while simultaneously achieving a high selectivity with irreversible nature required for effective 3O2 evolution. en-copyright= kn-copyright= en-aut-name=IsobeHiroshi en-aut-sei=Isobe en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=SuzukiTakayoshi en-aut-sei=Suzuki en-aut-mei=Takayoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=YamaguchiKizashi en-aut-sei=Yamaguchi en-aut-mei=Kizashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil= affil-num=2 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=3 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=4 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=5 en-affil=Center for Quantum Information and Quantum Biology, Osaka University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=9 cd-vols= no-issue=50 article-no= start-page=50041 end-page=50048 dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20241205 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Conformational Flexibility of D1-Glu189: A Crucial Determinant in Substrate Water Selection, Positioning, and Stabilization within the Oxygen-Evolving Complex of Photosystem II en-subtitle= kn-subtitle= en-abstract= kn-abstract=Photosynthetic water oxidation is a vital process responsible for producing dioxygen and supplying the energy necessary to sustain life on Earth. This fundamental reaction is catalyzed by the oxygen-evolving complex (OEC) of photosystem II, which houses the Mn4CaO5 cluster as its catalytic core. In this study, we specifically focus on the D1-Glu189 amino acid residue, which serves as a direct ligand to the Mn4CaO5 cluster. Our primary goal is to explore, using density functional theory (DFT), how the conformational flexibility of the D1-Glu189 side chain influences crucial catalytic processes, particularly the selection, positioning, and stabilization of a substrate water molecule within the OEC. Our investigation is based on a hypothesis put forth by Li et al. (Nature, 2024, 626, 670), which suggests that during the transition from the S2 to S3 state, a specific water molecule temporarily coordinating with the Ca ion, referred to as O6*, may exist as a hydroxide ion (OH-). Our results demonstrate a key mechanism by which the detachment of the D1-Glu189 carboxylate group from its coordination with the Ca ion allows the creation of a specialized microenvironment within the OEC that enables the selective attraction of O6* in its deprotonated form (OH-) and stabilizes it at the catalytic metal (MnD) site. Our findings indicate that D1-Glu189 is not only a structural ligand for the Ca ion but may also play an active and dynamic role in the catalytic process, positioning O6* optimally for its subsequent participation in the oxidation sequence during the water-splitting cycle. en-copyright= kn-copyright= en-aut-name=IsobeHiroshi en-aut-sei=Isobe en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=SuzukiTakayoshi en-aut-sei=Suzuki en-aut-mei=Takayoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=YamaguchiKizashi en-aut-sei=Yamaguchi en-aut-mei=Kizashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=2 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=3 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=4 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=5 en-affil=Center for Quantum Information and Quantum Biology, Osaka University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=626 cd-vols= no-issue=7999 article-no= start-page=670 end-page=677 dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240131 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Oxygen-evolving photosystem II structures during S1–S2–S3 transitions en-subtitle= kn-subtitle= en-abstract= kn-abstract=Photosystem II (PSII) catalyses the oxidation of water through a four-step cycle of Si states (i = 0–4) at the Mn4CaO5 cluster1,2,3, during which an extra oxygen (O6) is incorporated at the S3 state to form a possible dioxygen4,5,6,7. Structural changes of the metal cluster and its environment during the S-state transitions have been studied on the microsecond timescale. Here we use pump-probe serial femtosecond crystallography to reveal the structural dynamics of PSII from nanoseconds to milliseconds after illumination with one flash (1F) or two flashes (2F). YZ, a tyrosine residue that connects the reaction centre P680 and the Mn4CaO5 cluster, showed structural changes on a nanosecond timescale, as did its surrounding amino acid residues and water molecules, reflecting the fast transfer of electrons and protons after flash illumination. Notably, one water molecule emerged in the vicinity of Glu189 of the D1 subunit of PSII (D1-E189), and was bound to the Ca2+ ion on a sub-microsecond timescale after 2F illumination. This water molecule disappeared later with the concomitant increase of O6, suggesting that it is the origin of O6. We also observed concerted movements of water molecules in the O1, O4 and Cl-1 channels and their surrounding amino acid residues to complete the sequence of electron transfer, proton release and substrate water delivery. These results provide crucial insights into the structural dynamics of PSII during S-state transitions as well as O–O bond formation. en-copyright= kn-copyright= en-aut-name=LiHongjie en-aut-sei=Li en-aut-mei=Hongjie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=NakajimaYoshiki en-aut-sei=Nakajima en-aut-mei=Yoshiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=NangoEriko en-aut-sei=Nango en-aut-mei=Eriko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=OwadaShigeki en-aut-sei=Owada en-aut-mei=Shigeki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=YamadaDaichi en-aut-sei=Yamada en-aut-mei=Daichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=HashimotoKana en-aut-sei=Hashimoto en-aut-mei=Kana kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=LuoFangjia en-aut-sei=Luo en-aut-mei=Fangjia kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=TanakaRie en-aut-sei=Tanaka en-aut-mei=Rie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=AkitaFusamichi en-aut-sei=Akita en-aut-mei=Fusamichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=KatoKoji en-aut-sei=Kato en-aut-mei=Koji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=KangJungmin en-aut-sei=Kang en-aut-mei=Jungmin kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=SaitohYasunori en-aut-sei=Saitoh en-aut-mei=Yasunori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=KishiShunpei en-aut-sei=Kishi en-aut-mei=Shunpei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=YuHuaxin en-aut-sei=Yu en-aut-mei=Huaxin kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= en-aut-name=MatsubaraNaoki en-aut-sei=Matsubara en-aut-mei=Naoki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=15 ORCID= en-aut-name=FujiiHajime en-aut-sei=Fujii en-aut-mei=Hajime kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=16 ORCID= en-aut-name=SugaharaMichihiro en-aut-sei=Sugahara en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=17 ORCID= en-aut-name=SuzukiMamoru en-aut-sei=Suzuki en-aut-mei=Mamoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=18 ORCID= en-aut-name=MasudaTetsuya en-aut-sei=Masuda en-aut-mei=Tetsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=19 ORCID= en-aut-name=KimuraTetsunari en-aut-sei=Kimura en-aut-mei=Tetsunari kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=20 ORCID= en-aut-name=ThaoTran Nguyen en-aut-sei=Thao en-aut-mei=Tran Nguyen kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=21 ORCID= en-aut-name=YonekuraShinichiro en-aut-sei=Yonekura en-aut-mei=Shinichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=22 ORCID= en-aut-name=YuLong-Jiang en-aut-sei=Yu en-aut-mei=Long-Jiang kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=23 ORCID= en-aut-name=ToshaTakehiko en-aut-sei=Tosha en-aut-mei=Takehiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=24 ORCID= en-aut-name=TonoKensuke en-aut-sei=Tono en-aut-mei=Kensuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=25 ORCID= en-aut-name=JotiYasumasa en-aut-sei=Joti en-aut-mei=Yasumasa kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=26 ORCID= en-aut-name=HatsuiTakaki en-aut-sei=Hatsui en-aut-mei=Takaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=27 ORCID= en-aut-name=YabashiMakina en-aut-sei=Yabashi en-aut-mei=Makina kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=28 ORCID= en-aut-name=KuboMinoru en-aut-sei=Kubo en-aut-mei=Minoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=29 ORCID= en-aut-name=IwataSo en-aut-sei=Iwata en-aut-mei=So kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=30 ORCID= en-aut-name=IsobeHiroshi en-aut-sei=Isobe en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=31 ORCID= en-aut-name=YamaguchiKizashi en-aut-sei=Yamaguchi en-aut-mei=Kizashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=32 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=33 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=34 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Institute of Multidisciplinary Research for Advanced Materials, Tohoku University kn-affil= affil-num=4 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=5 en-affil=Department of Picobiology, Graduate School of Life Science, University of Hyogo kn-affil= affil-num=6 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=7 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=8 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=9 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=10 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=11 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=12 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=13 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=14 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=15 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=16 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=17 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=18 en-affil=Institute for Protein Research, Osaka University kn-affil= affil-num=19 en-affil=Division of Food and Nutrition, Faculty of Agriculture, Ryukoku University kn-affil= affil-num=20 en-affil=Department of Chemistry, Graduate School of Science, Kobe University kn-affil= affil-num=21 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=22 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=23 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=24 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=25 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=26 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=27 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=28 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=29 en-affil=Department of Picobiology, Graduate School of Life Science, University of Hyogo kn-affil= affil-num=30 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=31 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=32 en-affil=Center for Quantum Information and Quantum Biology, Osaka University kn-affil= affil-num=33 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=34 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=298 cd-vols= no-issue=12 article-no= start-page=102668 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=202212 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Crystal structures of photosystem II from a cyanobacterium expressing psbA2 in comparison to psbA3 reveal differences in the D1 subunit en-subtitle= kn-subtitle= en-abstract= kn-abstract=Three psbA genes (psbA1, psbA2, and psbA3) encoding the D1 subunit of photosystem II (PSII) are present in the ther-mophilic cyanobacterium Thermosynechococcus elongatus and are expressed differently in response to changes in the growth environment. To clarify the functional differences of the D1 protein expressed from these psbA genes, PSII dimers from two strains, each expressing only one psbA gene (psbA2 or psbA3), were crystallized, and we analyzed their structures at resolu-tions comparable to previously studied PsbA1-PSII. Our results showed that the hydrogen bond between pheophytin/D1 (PheoD1) and D1-130 became stronger in PsbA2-and PsbA3-PSII due to change of Gln to Glu, which partially explains the increase in the redox potential of PheoD1 observed in PsbA3. In PsbA2, one hydrogen bond was lost in PheoD1 due to the change of D1-Y147F, which may explain the decrease in stability of PheoD1 in PsbA2. Two water molecules in the Cl-1 channel were lost in PsbA2 due to the change of D1-P173M, leading to the narrowing of the channel, which may explain the lower efficiency of the S-state transition beyond S2 in PsbA2-PSII. In PsbA3-PSII, a hydrogen bond between D1-Ser270 and a sulfoquinovosyl-diacylglycerol molecule near QB dis-appeared due to the change of D1-Ser270 in PsbA1 and PsbA2 to D1-Ala270. This may result in an easier exchange of bound QB with free plastoquinone, hence an enhancement of oxygen evolution in PsbA3-PSII due to its high QB exchange efficiency. These results provide a structural basis for further functional examination of the three PsbA variants. en-copyright= kn-copyright= en-aut-name=NakajimaYoshiki en-aut-sei=Nakajima en-aut-mei=Yoshiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=Ugai-AmoNatsumi en-aut-sei=Ugai-Amo en-aut-mei=Natsumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=ToneNaoki en-aut-sei=Tone en-aut-mei=Naoki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NakagawaAkiko en-aut-sei=Nakagawa en-aut-mei=Akiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=IwaiMasako en-aut-sei=Iwai en-aut-mei=Masako kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=IkeuchiMasahiko en-aut-sei=Ikeuchi en-aut-mei=Masahiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=SugiuraMiwa en-aut-sei=Sugiura en-aut-mei=Miwa kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=Jian-RenShen en-aut-sei=Jian-Ren en-aut-mei=Shen kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Proteo-Science Research Center, Ehime University kn-affil= affil-num=5 en-affil=Graduate School and College of Arts and Sciences, The University of Tokyo kn-affil= affil-num=6 en-affil=Graduate School and College of Arts and Sciences, The University of Tokyo kn-affil= affil-num=7 en-affil=Proteo-Science Research Center, Ehime University kn-affil= affil-num=8 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=9 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=471 cd-vols= no-issue= article-no= start-page=214742 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=202211 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Geometric, electronic and spin structures of the CaMn4O5 catalyst for water oxidation in oxygen-evolving photosystem II. Interplay between experiments and theoretical computations en-subtitle= kn-subtitle= en-abstract= kn-abstract=The aim of this review is to elucidate geometric structures of the catalytic CaMn4Ox (x = 5, 6) cluster in the Kok cycle for water oxidation in the oxygen evolving complex (OEC) of photosystem II (PSII) based on the high-resolution (HR) X-ray diffraction (XRD) and serial femtosecond crystallography (SFX) experiments using the X-ray free-electron laser (XFEL). Quantum mechanics (QM) and QM/molecular mechanics (MM) computations are performed to elucidate the electronic and spin structures of the CaMn4Ox (x = 5, 6) cluster in five states S-i (i = 0 similar to 4) on the basis of the X-ray spectroscopy, electron paramagnetic resonance (EPR) and related experiments. Interplay between the experiments and theoretical computations has been effective to elucidate the coordination structures of the CaMn4Ox (x = 5, 6) cluster ligated by amino acid residues of the protein matrix of PSII, valence states of the four Mn ions and total spin states by their exchange-couplings, and proton-shifted isomers of the CaMn4Ox (x = 5, 6) cluster. The HR XRD and SFX XFEL experiments have also elucidated the biomolecular systems structure of OEC of PSII and the hydrogen bonding networks consisting of water molecules, chloride anions, etc., for water inlet and proton release pathways in PSII. Large-scale QM/MM computations have been performed for elucidation of the hydrogen bonding distances and angles by adding invisible hydrogen atoms to the HR XRD structure. Full geometry optimizations by the QM and QM/MM methods have been effective for elucidation of the molecular systems structure around the CaMn4Ox (x = 5, 6) cluster in OEC. DLPNO-CCSD(T-0) method has been applied to elucidate relative energies of possible intermediates in each state of the Kok cycle for water oxidation. Implications of these results are discussed in relation to the blueprint for developments of artificial catalysts for water oxidation. en-copyright= kn-copyright= en-aut-name=YamaguchiKizashi en-aut-sei=Yamaguchi en-aut-mei=Kizashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=ShojiMitsuo en-aut-sei=Shoji en-aut-mei=Mitsuo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=IsobeHiroshi en-aut-sei=Isobe en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KawakamiTakashi en-aut-sei=Kawakami en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MiyagawaKoichi en-aut-sei=Miyagawa en-aut-mei=Koichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=AkitaFusamichi en-aut-sei=Akita en-aut-mei=Fusamichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= affil-num=1 en-affil=Center for Quantum Information and Quantum Biology, Osaka University kn-affil= affil-num=2 en-affil=Center of Computational Sciences, Tsukuba University kn-affil= affil-num=3 en-affil=Research Institute for Interdisciplinary Science, and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=RIKEN Center for Computational Science kn-affil= affil-num=5 en-affil=Center of Computational Sciences, Tsukuba University kn-affil= affil-num=6 en-affil=Research Institute for Interdisciplinary Science, and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=7 en-affil=Research Institute for Interdisciplinary Science, and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=8 en-affil=Research Institute for Interdisciplinary Science, and Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=Water oxidation kn-keyword=Water oxidation en-keyword=Oxygen evolution kn-keyword=Oxygen evolution en-keyword=Photosystem II kn-keyword=Photosystem II en-keyword=HR XRD kn-keyword=HR XRD en-keyword=SFX XFEL kn-keyword=SFX XFEL en-keyword=QM/MM calculation kn-keyword=QM/MM calculation en-keyword=DLPNO CCSD(T-0) computations, Oxyl radical character kn-keyword=DLPNO CCSD(T-0) computations, Oxyl radical character END start-ver=1.4 cd-journal=joma no-vol=13 cd-vols= no-issue= article-no= start-page=982068 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20220912 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Structure and function of a silicic acid channel Lsi1 en-subtitle= kn-subtitle= en-abstract= kn-abstract=Silicon is a beneficial element for plant growth and production, especially in rice. Plant roots take up silicon in the form of silicic acid. Silicic acid channels, which belong to the NIP subfamily of aquaporins, are responsible for silicic acid uptake. Accumulated experimental results have deepened our understanding of the silicic acid channel for its uptake mechanism, physiological function, localization, and other aspects. However, how the silicic acid channel efficiently and selectively permeates silicic acid remains to be elucidated. Recently reported crystal structures of the silicic acid channel enabled us to discuss the mechanism of silicic acid uptake by plant roots at an atomic level. In this mini-review, we focus on the crystal structures of the silicic acid channel and provide a detailed description of the structural determinants of silicic acid permeation and its transport mechanism, which are crucial for the rational creation of secure and sustainable crops. en-copyright= kn-copyright= en-aut-name=SaitohYasunori en-aut-sei=Saitoh en-aut-mei=Yasunori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=2 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= en-keyword=silicon kn-keyword=silicon en-keyword=aquaporin kn-keyword=aquaporin en-keyword=NIP kn-keyword=NIP en-keyword=rice kn-keyword=rice en-keyword=crystal structure kn-keyword=crystal structure en-keyword=substrate selectivity kn-keyword=substrate selectivity en-keyword=channel kn-keyword=channel en-keyword=transporter kn-keyword=transporter END start-ver=1.4 cd-journal=joma no-vol=12 cd-vols= no-issue=1 article-no= start-page=6236 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=20211029 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Structural basis for high selectivity of a rice silicon channel Lsi1 en-subtitle= kn-subtitle= en-abstract= kn-abstract=Silicon (Si), the most abundant mineral element in the earth’s crust, is taken up by plant roots in the form of silicic acid through Low silicon rice 1 (Lsi1). Lsi1 belongs to the Nodulin 26-like intrinsic protein subfamily in aquaporin and shows high selectivity for silicic acid. To uncover the structural basis for this high selectivity, here we show the crystal structure of the rice Lsi1 at a resolution of 1.8 Å. The structure reveals transmembrane helical orientations different from other aquaporins, characterized by a unique, widely opened, and hydrophilic selectivity filter (SF) composed of five residues. Our structural, functional, and theoretical investigations provide a solid structural basis for the Si uptake mechanism in plants, which will contribute to secure and sustainable rice production by manipulating Lsi1 selectivity for different metalloids. en-copyright= kn-copyright= en-aut-name=SaitohYasunori en-aut-sei=Saitoh en-aut-mei=Yasunori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=Mitani-UenoNamiki en-aut-sei=Mitani-Ueno en-aut-mei=Namiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=SaitoKeisuke en-aut-sei=Saito en-aut-mei=Keisuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MatsukiKengo en-aut-sei=Matsuki en-aut-mei=Kengo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=HuangSheng en-aut-sei=Huang en-aut-mei=Sheng kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=YangLingli en-aut-sei=Yang en-aut-mei=Lingli kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=YamajiNaoki en-aut-sei=Yamaji en-aut-mei=Naoki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=IshikitaHiroshi en-aut-sei=Ishikita en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=MaJian Feng en-aut-sei=Ma en-aut-mei=Jian Feng kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=2 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=3 en-affil=Research Center for Advanced Science and Technology, The University of Tokyo kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=6 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=7 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=8 en-affil=Research Center for Advanced Science and Technology, The University of Tokyo kn-affil= affil-num=9 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=10 en-affil=Institute of Plant Science and Resources, Okayama University kn-affil= affil-num=11 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=1864 cd-vols= no-issue=2 article-no= start-page=129466 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=20200229 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Time-resolved studies of metalloproteins using X-ray free electron laser radiation at SACLA en-subtitle= kn-subtitle= en-abstract= kn-abstract=Background: The invention of the X-ray free-electron laser (XFEL) has provided unprecedented new opportunities for structural biology. The advantage of XFEL is an intense pulse of X-rays and a very short pulse duration (<10 fs) promising a damage-free and time-resolved crystallography approach.
Scope of review: Recent time-resolved crystallographic analyses in XFEL facility SACLA are reviewed. Specifically, metalloproteins involved in the essential reactions of bioenergy conversion including photosystem II, cytochrome c oxidase and nitric oxide reductase are described.
Major conclusions: XFEL with pump-probe techniques successfully visualized the process of the reaction and the dynamics of a protein. Since the active center of metalloproteins is very sensitive to the X-ray radiation, damage-free structures obtained by XFEL are essential to draw mechanistic conclusions. Methods and tools for sample delivery and reaction initiation are key for successful measurement of the time-resolved data.
General significance: XFEL is at the center of approaches to gain insight into complex mechanism of structural dynamics and the reactions catalyzed by biological macromolecules. Further development has been carried out to expand the application of time-resolved X-ray crystallography. This article is part of a Special Issue entitled Novel measurement techniques for visualizing 'live' protein molecules. en-copyright= kn-copyright= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=ShimadaAtsuhiro en-aut-sei=Shimada en-aut-mei=Atsuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=AkitaFusamichi en-aut-sei=Akita en-aut-mei=Fusamichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=ToshaTakehiko en-aut-sei=Tosha en-aut-mei=Takehiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=SugimotoHiroshi en-aut-sei=Sugimoto en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Applied Biological Sciences and Faculty of Applied Biological Sciences, Gifu University kn-affil= affil-num=3 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Synchrotron Radiation Life Science Instrumentation Team, RIKEN SPring-8 Center kn-affil= affil-num=6 en-affil=Synchrotron Radiation Life Science Instrumentation Team, RIKEN SPring-8 Center kn-affil= en-keyword=Heme kn-keyword=Heme en-keyword=Metalloproteins kn-keyword=Metalloproteins en-keyword=Proton pump kn-keyword=Proton pump en-keyword=Radiation damage kn-keyword=Radiation damage en-keyword=Serial femtosecond crystallography kn-keyword=Serial femtosecond crystallography en-keyword=X-ray free-electron laser kn-keyword=X-ray free-electron laser END start-ver=1.4 cd-journal=joma no-vol=366 cd-vols= no-issue=6463 article-no= start-page=334 end-page=338 dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20191018 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=An oxyl/oxo mechanism for dioxygen bond formation in PSII revealed by X-ray free electron lasers en-subtitle= kn-subtitle= en-abstract= kn-abstract= Photosynthetic water oxidation is catalyzed by the Mn4CaO5 cluster of photosystem II (PSII) with linear progression through five S-state intermediates (S0 to S4). To reveal the mechanism of water oxidation, we analyzed structures of PSII in the S1, S2, and S3 states by x-ray free-electron laser serial crystallography. No insertion of water was found in S2, but flipping of D1 Glu189 upon transition to S3 leads to the opening of a water channel and provides a space for incorporation of an additional oxygen ligand, resulting in an open cubane Mn4CaO6 cluster with an oxyl/oxo bridge. Structural changes of PSII between the different S states reveal cooperative action of substrate water access, proton release, and dioxygen formation in photosynthetic water oxidation. en-copyright= kn-copyright= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=AkitaFusamichi en-aut-sei=Akita en-aut-mei=Fusamichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YamashitaKeitaro en-aut-sei=Yamashita en-aut-mei=Keitaro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NakajimaYoshiki en-aut-sei=Nakajima en-aut-mei=Yoshiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=UenoGo en-aut-sei=Ueno en-aut-mei=Go kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=LiHongjie en-aut-sei=Li en-aut-mei=Hongjie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=YamaneTakahiro en-aut-sei=Yamane en-aut-mei=Takahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=HirataKunio en-aut-sei=Hirata en-aut-mei=Kunio kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=UmenaYasufumi en-aut-sei=Umena en-aut-mei=Yasufumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=YonekuraShinichiro en-aut-sei=Yonekura en-aut-mei=Shinichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=YuLong-Jiang en-aut-sei=Yu en-aut-mei=Long-Jiang kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=MurakamiHironori en-aut-sei=Murakami en-aut-mei=Hironori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=NomuraTakashi en-aut-sei=Nomura en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=KimuraTetsunari en-aut-sei=Kimura en-aut-mei=Tetsunari kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= en-aut-name=KuboMinoru en-aut-sei=Kubo en-aut-mei=Minoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=15 ORCID= en-aut-name=BabaSeiki en-aut-sei=Baba en-aut-mei=Seiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=16 ORCID= en-aut-name=KumasakaTakashi en-aut-sei=Kumasaka en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=17 ORCID= en-aut-name=TonoKensuke en-aut-sei=Tono en-aut-mei=Kensuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=18 ORCID= en-aut-name=YabashiMakina en-aut-sei=Yabashi en-aut-mei=Makina kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=19 ORCID= en-aut-name=IsobeHiroshi en-aut-sei=Isobe en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=20 ORCID= en-aut-name=YamaguchiKizashi en-aut-sei=Yamaguchi en-aut-mei=Kizashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=21 ORCID= en-aut-name=YamamotoMasaki en-aut-sei=Yamamoto en-aut-mei=Masaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=22 ORCID= en-aut-name=AgoHideo en-aut-sei=Ago en-aut-mei=Hideo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=23 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=24 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=4 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=6 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=7 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=8 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=9 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=10 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=11 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=12 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=13 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=14 en-affil=Department of Chemistry, Graduate School of Science, Kobe University kn-affil= affil-num=15 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=16 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=17 en-affil=Japan Synchrotron Radiation Research Institute kn-affil= affil-num=18 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=19 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=20 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=21 en-affil=The Institute for Scientific and Industrial Research, Osaka University kn-affil= affil-num=22 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=23 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=24 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=292 cd-vols= no-issue=23 article-no= start-page=9599 end-page=9612 dt-received= dt-revised= dt-accepted= dt-pub-year=2017 dt-pub=201706 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Crystal structure and redox properties of a novel cyanobacterial heme protein with a His/Cys heme axial ligation and a Per-Arnt-Sim (PAS)-like domain en-subtitle= kn-subtitle= en-abstract= kn-abstract= Photosystem II catalyzes light-induced water oxidation leading to the generation of dioxygen indispensable for sustaining aerobic life on Earth. The Photosystem II reaction center is composed of D1 and D2 proteins encoded by psbA and psbD genes, respectively. In cyanobacteria, different psbA genes are present in the genome. The thermophilic cyanobacterium Thermosynechococcus elongatus contains three psbA genes: psbA1, psbA2, and psbA3, and a new c-type heme protein, Tll0287, was found to be expressed in a strain expressing the psbA2 gene only, but the structure and function of Tll0287 are unknown. Here we solved the crystal structure of Tll0287 at a 2.0 Å resolution. The overall structure of Tll0287 was found to be similar to some kinases and sensor proteins with a Per-Arnt-Sim-like domain rather than to other c-type cytochromes. The fifth and sixth axial ligands for the heme were Cys and His, instead of the His/Met or His/His ligand pairs observed for most of the c-type hemes. The redox potential, E½, of Tll0287 was -255 ± 20 mV versus normal hydrogen electrode at pH values above 7.5. Below this pH value, the E½ increased by ≈57 mV/pH unit at 15 °C, suggesting the involvement of a protonatable group with a pKred = 7.2 ± 0.3. Possible functions of Tll0287 as a redox sensor under microaerobic conditions or a cytochrome subunit of an H2S-oxidizing system are discussed in view of the environmental conditions in which psbA2 is expressed, as well as phylogenetic analysis, structural, and sequence homologies. en-copyright= kn-copyright= en-aut-name=MotomuraTaiki en-aut-sei=Motomura en-aut-mei=Taiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HienerwadelRainer en-aut-sei=Hienerwadel en-aut-mei=Rainer kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NakagawaAkiko en-aut-sei=Nakagawa en-aut-mei=Akiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=LaiThanh-Lan en-aut-sei=Lai en-aut-mei=Thanh-Lan kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=NitschkeWolfgang en-aut-sei=Nitschke en-aut-mei=Wolfgang kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=KumaTakahiro en-aut-sei=Kuma en-aut-mei=Takahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=SugiuraMiwa en-aut-sei=Sugiura en-aut-mei=Miwa kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=BoussacAlain en-aut-sei=Boussac en-aut-mei=Alain kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= affil-num=1 en-affil=the Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=the Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil= the Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, CNRS-CEA-Aix-Marseille Université, Faculté des Sciences de Luminy kn-affil= affil-num=4 en-affil= the Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil= iBiTec-S kn-affil= affil-num=6 en-affil= the Laboratoire de Bioénergétique et Ingénierie des Protéines kn-affil= affil-num=7 en-affil= the Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=8 en-affil=the Proteo-Science Research Center, Ehime University kn-affil= affil-num=9 en-affil=iBiTec-S kn-affil= affil-num=10 en-affil= the Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=D1 protein kn-keyword=D1 protein en-keyword=His-Cys heme axial coordination kn-keyword=His-Cys heme axial coordination en-keyword=PAS domain kn-keyword=PAS domain en-keyword=PAS-like domain kn-keyword=PAS-like domain en-keyword=Tll0287 kn-keyword=Tll0287 en-keyword=X-ray crystallography kn-keyword=X-ray crystallography en-keyword=cytochrome kn-keyword=cytochrome en-keyword=heme kn-keyword=heme en-keyword=photosynthesis kn-keyword=photosynthesis en-keyword=photosystem II kn-keyword=photosystem II END start-ver=1.4 cd-journal=joma no-vol=39 cd-vols= no-issue= article-no= start-page=46 end-page=53 dt-received= dt-revised= dt-accepted= dt-pub-year=2016 dt-pub=201608 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Structure and energy transfer pathways of the plant photosystem I-LHCI supercomplex en-subtitle= kn-subtitle= en-abstract= kn-abstract=Photosystem I (PSI) is one of the two photosystems in oxygenic photosynthesis, and absorbs light energy to generate reducing power for the reduction of NADP+ to NADPH with a quantum efficiency close to 100%. The plant PSI core forms a supercomplex with light-harvesting complex I (LHCI) with a total molecular weight of over 600 kDa. Recent X-ray structure analysis of the PSI-LHCI membrane-protein supercomplex has revealed detailed arrangement of the light-harvesting pigments and other cofactors especially within LHCI. Here we introduce the overall structure of the PSI-LHCI supercomplex, and then focus on the excited energy transfer (EET) pathways from LHCI to the PSI core and photoprotection mechanisms based on the structure obtained. en-copyright= kn-copyright= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name=菅倫寛 kn-aut-sei=菅 kn-aut-mei=倫寛 aut-affil-num=1 ORCID= en-aut-name=QinXiaochun en-aut-sei=Qin en-aut-mei=Xiaochun kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KuangTingyun en-aut-sei=Kuang en-aut-mei=Tingyun kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name=沈建仁 kn-aut-sei=沈 kn-aut-mei=建仁 aut-affil-num=4 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil=岡山大学異分野基礎科学研究所 affil-num=2 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil=岡山大学異分野基礎科学研究所 affil-num=3 en-affil=Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences kn-affil= affil-num=4 en-affil=Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University kn-affil=岡山大学異分野基礎科学研究所 END