記述言語：日本語  

Web of Science

記述言語：日本語   出版者・発行元：Science  

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 reve cooperative action of substrate water access, proton release, and dioxygen formation in photosynthetic water oxidation.

DOI： 10.1126/science.aax6998

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DOI： 10.1107/S2053273314084976

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DOI： 10.1107/S2053273314096491

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DOI： 10.1107/S0108767311091082

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DOI： 10.1080/00405000.2010.498974

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掲載種別：研究論文（学術雑誌）  

DOI： 10.35848/1347-4065/acc3a9

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.bbrc.2021.06.078

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IUCrJ  

Photosystem II (PSII) catalyzes light-induced water oxidation through an S i-state cycle, leading to the generation of di-oxygen, protons and electrons. Pump-probe time-resolved serial femtosecond crystallography (TR-SFX) has been used to capture structural dynamics of light-sensitive proteins. In this approach, it is crucial to avoid light contamination in the samples when analyzing a particular reaction intermediate. Here, a method for determining a condition that avoids light contamination of the PSII microcrystals while minimizing sample consumption in TR-SFX is described. By swapping the pump and probe pulses with a very short delay between them, the structural changes that occur during the S1-to-S2 transition were examined and a boundary of the excitation region was accurately determined. With the sample flow rate and concomitant illumination conditions determined, the S2-state structure of PSII could be analyzed at room temperature, revealing the structural changes that occur during the S1-to-S2 transition at ambient temperature. Though the structure of the manganese cluster was similar to previous studies, the behaviors of the water molecules in the two channels (O1 and O4 channels) were found to be different. By comparing with the previous studies performed at low temperature or with a different delay time, the possible channels for water inlet and structural changes important for the water-splitting reaction were revealed.

DOI： 10.1107/S2052252521002177

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In the present study, we provide a reformulation of the theory originally proposed by Forster which allows for simple and convenient formulas useful to estimate the relative contributions of transition dipole moments of a donor and acceptor (chemical factors), their orientation factors (intermolecular structural factors), inter-molecular center-to-center distances (intermolecular structural factors), spectral overlaps of absorption and emission spectra (photophysical factors), and refractive index (material factor) to the excitation energy transfer (EET) rate constant. To benchmark their validity, we focused on the EET occurring in C-phycocyanin (C-PC) chromophores. To this aim, we resorted to quantum chemistry calculations to get optimized molecular structures of the C-PC chromophores within the density functional theory (DFT) framework. The absorption and emission spectra, as well as transition dipole moments, were computed by using the time-dependent DFT (TDDFT). Our method was applied to several types of C-PCs showing that the EET rates are determined by an interplay of their specific physical, chemical, and geometrical features. These results show that our formulas can become a useful tool for a reliable estimation of the relative contributions of the factors regulating the EET transfer rate.

DOI： 10.2142/biophysico.bppb-v18.021

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1246/bcsj.20200187

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Physical Chemistry Letters  

The high-spin S2 state was investigated with photosystem II (PSII) from spinach, Thermosynechococcus vulcanus, and Cyanidioschyzon merolae. In extrinsic protein-depleted PSII, high-spin electron paramagnetic resonance (EPR) signals were not detected in either species, whereas all species showed g ∼5 signals in the presence of a high concentration of Ca2+ instead of the multiline signal. In the intact and PsbP/Q-depleted PSII from spinach, the g = 4.1 EPR signal was detected. These results show that formation of the high-spin S2 state of the manganese cluster is regulated by the extrinsic proteins through a charge located near the Mn4 atom in the Mn4CaO5 cluster but is independent of the intrinsic proteins. The shift to the g ∼5 state is caused by tilting of the z-axis in the Mn4 coordinates through hydrogen bonds or external divalent cations. The structural modification may allow insertion of an oxygen atom during the S2-to-S3 transition.

DOI： 10.1021/acs.jpclett.0c02411

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Biochimica et Biophysica Acta - Bioenergetics  

Photosynthetic [2Fe-2S] plant-type ferredoxins have a central role in electron transfer between the photosynthetic chain and various metabolic pathways. Several genes are coding for [2Fe–2S] ferredoxins in cyanobacteria, with four in the thermophilic cyanobacterium Thermosynechococcus elongatus. The structure and functional properties of the major ferredoxin Fd1 are well known but data on the other ferredoxins are scarce. We report the structural and functional properties of a novel minor type ferredoxin, Fd2 of T. elongatus, homologous to Fed4 from Synechocystis sp. PCC 6803. Remarkably, the midpoint potential of Fd2, Em = −440 mV, is lower than that of Fd1, Em = −372 mV. However, while Fd2 can efficiently react with photosystem I or nitrite reductase, time-resolved spectroscopy shows that Fd2 has a very low capacity to reduce ferredoxin-NADP+ oxidoreductase (FNR). These unique Fd2 properties are discussed in relation with its structure, solved at 1.38 Å resolution. The Fd2 structure significantly differs from other known ferredoxins structures in loop 2, N-terminal region, hydrogen bonding networks and surface charge distributions. UV–Vis, EPR, and Mid- and Far-IR data also show that the electronic properties of the [2Fe–2S] cluster of Fd2 and its interaction with the protein differ from those of Fd1 both in the oxidized and reduced states. The structural analysis allows to propose that valine in the motif Cys53ValAsnCys56 of Fd2 and the specific orientation of Phe72, explain the electron transfer properties of Fd2. Strikingly, the nature of these residues correlates with different phylogenetic groups of cyanobacterial Fds. With its low redox potential and its discrimination against FNR, Fd2 exhibits a unique capacity to direct efficiently photosynthetic electrons to metabolic pathways not dependent on FNR.

DOI： 10.1016/j.bbabio.2019.148084

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AIP Publishing  

<jats:p>An experimental system, SPINETT (SACLA Pump-probe INstrumEnt for Tracking Transient dynamics), dedicated for ultrafast pump-probe experiments using X-ray free-electron lasers has been developed. SPINETT consists of a chamber operated under 1 atm helium pressure, two Von Hamos spectrometers, and a large two-dimensional detector having a short work distance. This platform covers complementary X-ray techniques; one can perform time-resolved X-ray absorption spectroscopy, time-resolved X-ray emission spectroscopy, and time-resolved X-ray diffuse scattering. Two types of liquid injectors have been prepared for low-viscosity chemical solutions and for protein microcrystals embedded in a matrix. We performed a test experiment at SPring-8 Angstrom Compact free-electron LAser and demonstrated the capability of SPINETT to obtain the local electronic structure and geometrical information simultaneously.</jats:p>

DOI： 10.1063/1.5111795

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

The dynamics of the intact photosystem II core complex (PSII-CC) has been investigated extensively to elucidate its excellent photofunction. However, it is significantly difficult to observe the primary photosynthetic processes in PSII-CC because a vast number of chlorophylls (Chl) in the core complex show similar spectral features. In the present work, the dynamics of the energy transfer (ET) from β-carotene (Bcr) in intact PSII-CC followed by charge separation (CS) at the reaction center (RC) with different excitation wavelengths were compared. Upon excitation at 510 nm, which selectively excites Bcr (Bcr651) inside of the D1-D2 RC, the pheophytin anion absorption band appeared within 9.6 ps. On the other hand, upon excitation at 490 nm, mainly exciting unspecified Bcr in the antenna complex, the anion band appeared after 20 ps. These excitation wavelength dependence experiments revealed a new ET pathway of PSII-CC, which indicates that the initial CS of PSII-CC is limited by ET to the RC.

DOI： 10.1021/acs.jpclett.9b01072

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Physical Society of Japan  

The photosynthetic water oxidation reaction in photosystem II (PSII) causes the ejection of four protons (H+) and electrons from the substrate water bound to the Mn4CaO5 cluster, denoting the catalytic center of the system. Two Cl− ions, Cl1 and Cl2 sites, were found in the vicinity of the Mn4CaO5 moiety. Herein, a novel H+ transfer mechanism (amide H+ exchange-driven scheme) was identified to operate in the Cl2 pathway based on the hybrid ab initio quantum mechanics (QM) molecular dynamics (MD) simulations of PSII. The analysis revealed that H+ can be displaced across the peptide bond of the D1-His337 and D1-Asn338 backbones, interrupting the hydrogen bond network spanning to the lumenal side in the crystal structure. The estimated energy barrier was consistent with the previous kinetic data. This is the first report to address unidirectional H+ transfer through a peptide bond based on the theoretical analysis involving the environmental protein structure.

DOI： 10.7566/JPSJ.88.084802

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Association for the Advancement of Science (AAAS)  

<jats:title>All the hues, even the blues</jats:title>
<jats:p>
Photosynthetic organisms must balance maximizing productive light absorption and protecting themselves from too much light, which causes damage. Both tasks require pigments—chlorophylls and carotenoids—which absorb light energy and either transfer it to photosystems or disperse it as heat. Wang
<jats:italic>et al.</jats:italic>
determined the structure of a fucoxanthin chlorophyll a/c–binding protein (FCP) from a diatom. The structure reveals the arrangement of the specialized photosynthetic pigments in this light-harvesting protein. Fucoxanthin and chlorophyll c absorb the blue-green light that penetrates to deeper water and is not absorbed well by chlorophylls a or b. FCPs are related to the light-harvesting complexes of plants but have more binding sites for carotenoids and fewer for chlorophylls, which may help transfer and disperse light energy.
</jats:p>
<jats:p>
<jats:italic>Science</jats:italic>
, this issue p.
<jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.aav0365">eaav0365</jats:related-article>
</jats:p>

DOI： 10.1126/science.aav0365

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記述言語：英語  

DOI： 10.1107/S010876731909648X

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記述言語：英語   出版者・発行元：Advances in Quantum Chemistry  

Atmospheric oxygenation and evolution of aerobic life on our earth are a result of water oxidation by oxygenic photosynthesis in photosystem II (PSII) of plants, algae, and cyanobacteria. The water oxidation in the oxygen-evolving complex (OEC) of PSII is expected to proceed through five oxidation states, known as the Si (i = 0, 1, 2, 3, and 4) states in the Kok cycle, with the S1 being the most stable state in the dark. The OEC in PSII involves the active catalytic site made of four Mn ions and one Ca ion, namely the CaMn4O5 cluster. Past decades, molecular structures of the CaMn4O5 cluster in OEC of PSII have been investigated by the extended X-ray absorption fine structure (EXAFS). The magnetostructural correlations were extensively investigated by EPR spectroscopy. Recently, Kamiya and Shen groups made a great breakthrough for determination of the S1 structure of OEC of PSII by the X-ray diffraction (XRD) and X-ray free electron laser (XFEL) experiments, providing structural foundations that are crucial for theoretical investigations of structure and reactivity of the CaMn4O5 cluster. Large-scale QM/MM calculations starting from the XRD structures elucidated geometrical, electronic, and spin structures of the CaMn4O5 cluster, indicating an important role of the Jahn–Teller (JT) effect of Mn(III) ions. This review fully examines our theoretical formulae for estimation of the Jahn–Teller deformations of the CaMn4O5 cluster in OEC of PSII. Scope and applicability of the JT deformation formulae are elucidated in relation to several different structures of the CaMn4O5 cluster proposed by XRD, XFEL, EXAFS, and other experiments. Subtle differences among XRD, XFEL, and EXAFS structures in the S1 state are examined in relation to environmental effects for the CaMn4O5 cluster in OEC of PSII. The X-ray damage of the serial femtosecond crystallography (SFX) by XFEL is also examined in relation to the damage-free low-dose (LD) XRD structure. The JT deformation formulae are also applied to theoretical analysis of the S3 structures by SFX. Implications of the computational results are discussed for further refinements of geometrical parameters of the CaMn4O5 cluster in OEC of PSII and possible mechanisms of water oxidation in OEC of PSII.

DOI： 10.1016/bs.aiq.2018.05.003

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1074/jbc.RA118.004304

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

Photosynthetic water oxidation is performed in photosystem II (PSII) through a light-driven cycle of intermediates called S states (S

DOI： 10.1021/acs.jpclett.8b00638

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

<jats:title>Abstract</jats:title><jats:p>Tanaka et al. (<jats:italic>J. Am. Chem. Soc</jats:italic>., <jats:bold>2017</jats:bold>, <jats:italic>139</jats:italic>, 1718) recently reported the three‐dimensional (3D) structure of the oxygen evolving complex (OEC) of photosystem II (PSII) by X‐ray diffraction (XRD) using extremely low X‐ray doses of 0.03 and 0.12 MGy. They observed two different 3D structures of the CaMn<jats:sub>4</jats:sub>O<jats:sub>5</jats:sub> cluster with different hydrogen‐bonding interactions in the S<jats:sub>1</jats:sub> state of OEC keeping the surrounding polypeptide frameworks of PSII the same. Our Jahn–Teller (JT) deformation formula based on large‐scale quantum mechanics/molecular mechanics (QM/MM) was applied for these low‐dose XRD structures, elucidating important roles of JT effects of the Mn<jats:sup>III</jats:sup> ion for subtle geometric distortions of the CaMn<jats:sub>4</jats:sub>O<jats:sub>5</jats:sub> cluster in OEC of PSII. The JT deformation formula revealed the similarity between the low‐dose XRD and damage‐free serial femtosecond X‐ray diffraction (SFX) structures of the CaMn<jats:sub>4</jats:sub>O<jats:sub>5</jats:sub> cluster in the dark stable state. The extremely low‐dose XRD structures were not damaged by X‐ray irradiation. Implications of the present results are discussed in relation to recent SFX results and a blue print for the design of artificial photocatalysts for water oxidation.</jats:p>

DOI： 10.1002/cptc.201700162

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Royal Society of Chemistry (RSC)  

<p>Photosystem II (PSII) is a membrane protein complex that performs light-induced electron transfer and oxygen evolution from water. PSII consists of 19 or 20 subunits in its crystal form and binds various cofactors such as chlorophyll a, plastoquinone, carotenoid, and lipids. After initial light excitation, the charge separation produces an electron, which is transferred to a plastoquinone molecule (Q_A) and then to another plastoquinone (Q_B). PsbM is a low-molecular-weight subunit with one transmembrane helix, and is located in the monomer–monomer interface of the PSII dimer. The function of PsbM has been reported to be stabilization of the PSII dimer and maintenance of electron transfer efficiency of PSII based on previous X-ray crystal structure analysis at a resolution of 4.2 Å. In order to elucidate the structure–function relationships of PsbM in detail, we improved the quality of PSII crystals from a PsbM-deleted mutant (ΔPsbM-PSII) of <italic>Thermosynechococcus elongatus</italic>, and succeeded in improving the diffraction quality to a resolution of 2.2 Å. X-ray crystal structure analysis of ΔPsbM-PSII showed that electron densities for the PsbM subunit and neighboring carotenoid and detergent molecules were absent in the monomer–monomer interface. The overall structure of ΔPsbM-PSII was similar to wild-type PSII, but the arrangement of the hydrophobic transmembrane subunits was significantly changed by the deletion of PsbM, resulting in a slight widening of the lipid hole involving Q_B. The lipid hole-widening further induced structural changes of the bicarbonate ion coordinated to the non-heme Fe(<sc>ii</sc>) atom and destabilized the polypeptide chains around the Q_B binding site located far from the position of PsbM. The fluorescence decay measurement indicated that the electron transfer rate from Q_A to Q_B was decreased in ΔPsbM-PSII compared with wild-type PSII. The functional change in electron transfer efficiency was fully interpreted based on structural changes caused by the deletion of the PsbM subunit.</p>

DOI： 10.1039/c6fd00213g

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/nature21400

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記述言語：英語  

DOI： 10.1107/S205327331709475X

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

Energy transfer dynamics in monomer and dimer of the photosystem II core complex (PSII-CC) was investigated by means of femtosecond transient absorption (TA) spectroscopy. There is no profound difference between the TA dynamics of the monomer and the dimer in the weak excitation intensity condition (≤21 nJ). However, the fast recovery of the ground state bleach was pronounced at higher excitation intensities, and the excitation intensity dependence of the dimer was more significant than that of the monomer. This result indicates efficient exciton-exciton annihilation taking place in the dimer due to energy transfer between the two monomer units. The annihilation dynamics was reproduced by a simple model based on binomial theorem, which indicated that although PSII-CC dimer has two reaction centers, only one charge-separated state remained after annihilation.

DOI： 10.1021/jacs.6b04316

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：OSA - The Optical Society  

Energy transfer dynamics of photosystem II monomer and dimer were compared by femtosecond transient absorption (TA) spectroscopy. Excitation energy dependence suggested more excellent quenching ability of dimer by exciton-exciton annihilation.

DOI： 10.1364/UP.2016.UTu4A.40

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1074/jbc.M115.711689

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Royal Society of Chemistry (RSC)  

<p>Broken-symmetry UB3LYP calculations have elucidated structural symmetry-breaking in the S₁ and S₃ states of the oxygen evolution complex (OEC) of photosystem II (PSII), providing the right (RO)- and left (LO)-opened structures.</p>

DOI： 10.1039/c4cp00282b

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

The electron density map of the 3D crystal of Photosystem II from Thermosynechococcus vulcanus with a 1.9 Å resolution (PDB: 3ARC ) exhibits, in the two monomers in the asymmetric unit cell, an, until now, unidentified and uninterpreted strong difference in electron density centered at a distance of around 1.5 Å from the nitrogen Nδ of the imidazole ring of D2-His336. By MALDI-TOF/MS upon tryptic digestion, it is shown that ~20-30% of the fragments containing the D2-His336 residue of Photosystem II from both Thermosynechococcus vulcanus and Thermosynechococcus elongatus bear an extra mass of +16 Da. Such an extra mass likely corresponds to an unprecedented post-translational or chemical hydroxyl modification of histidine.

DOI： 10.1021/bi401213m

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Proceedings of the National Academy of Sciences  

<jats:p>Oxygen-evolving complex of photosystem II (PSII) is a tetra-manganese calcium penta-oxygenic cluster (Mn<jats:sub>4</jats:sub>CaO<jats:sub>5</jats:sub>) catalyzing light-induced water oxidation through several intermediate states (S-states) by a mechanism that is not fully understood. To elucidate the roles of Ca<jats:sup>2+</jats:sup>in this cluster and the possible location of water substrates in this process, we crystallized Sr<jats:sup>2+</jats:sup>-substituted PSII from<jats:italic>Thermosynechococcus vulcanus</jats:italic>, analyzed its crystal structure at a resolution of 2.1 Å, and compared it with the 1.9 Å structure of native PSII. Our analysis showed that the position of Sr was moved toward the outside of the cubane structure of the Mn<jats:sub>4</jats:sub>CaO<jats:sub>5</jats:sub>-cluster relative to that of Ca<jats:sup>2+</jats:sup>, resulting in a general elongation of the bond distances between Sr and its surrounding atoms compared with the corresponding distances in the Ca-containing cluster. In particular, we identified an apparent elongation in the bond distance between Sr and one of the two terminal water ligands of Ca<jats:sup>2+</jats:sup>, W3, whereas that of the Sr-W4 distance was not much changed. This result may contribute to the decrease of oxygen evolution upon Sr<jats:sup>2+</jats:sup>-substitution, and suggests a weak binding and rather mobile nature of this particular water molecule (W3), which in turn implies the possible involvement of this water molecule as a substrate in the O-O bond formation. In addition, the PsbY subunit, which was absent in the 1.9 Å structure of native PSII, was found in the Sr-PSII structure.</jats:p>

DOI： 10.1073/pnas.1219922110

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/qua.24280

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/qua.24117

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1063/1.4848085

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記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Springer  

Broken-symmetry (BS) UB3LYP calculations have been performed for the CaMn4O5 cluster (1) in the oxygen-evolving complex (OEC) of the PSII system refined to 1.9 Å resolution by Umena, Kawakami, Kamiya, Shen to elucidate its electronic structure that is crucial for consideration of possible mechanisms of photosynthetic water splitting. Our UB3LYP computations have elucidated the position of protonated oxygen of the CaMn(III)2Mn(IV)2O4(OH) cluster (1a) at the S1 stage of Kok cycle. Starting from the newly elucidated S1 structure of 1a, we have calculated the electronic structure of proton and electron released CaMn(IV)4O5 cluster (1b) that mimics the S4 stage of the cycle. The LUMOs of 1b are depicted for pictorial understanding of electrophilic oxygen sites that are responsible for nucleophilic attack of hydroxide anion (or water) for the O-O bond formation. Implications of present computational results are discussed in relation to possible mechanisms of photosynthetic water splitting.

DOI： 10.1007/978-3-642-32034-7_52

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記述言語：英語  

DOI： 10.1016/j.bbabio.2012.06.016

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

The crystal structure of Photosystem II (PSII) analyzed at a resolution of 1.9 Å revealed deformations of chlorin rings in the chlorophylls for the first time. We investigated the degrees of chlorin ring deformation and factors that contributed to them in the PSII crystal structure, using a normal-coordinate structural decomposition procedure. The out-of-plane distortion of the P(D1) chlorin ring can be described predominantly by a large "doming mode" arising from the axial ligand, D1-His198, as well as the chlorophyll side chains and PSII protein environment. In contrast, the deformation of P(D2) was caused by a "saddling mode" arising from the D2-Trp191 ring and the doming mode arising from D2-His197. Large ruffling modes, which were reported to lower the redox potential in heme proteins, were observed in P(D1) and Chl(D1), but not in P(D2) and Chl(D2). Furthermore, as P(D1) possessed the largest doming mode among the reaction center chlorophylls, the corresponding bacteriochlorophyll P(L) possessed the largest doming mode in bacterial photosynthetic reaction centers. However, the majority of the redox potential shift in the protein environment was determined by the electrostatic environment. The difference in the chlorin ring deformation appears to directly refer to the difference in "the local steric protein environment" rather than the redox potential value in PSII.

DOI： 10.1021/bi300428s

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/qua.23261

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/qua.23218

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c2dt31420g

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記述言語：英語   掲載種別：論文集(書籍)内論文  

DOI： 10.1016/B978-0-12-396498-4.00016-8

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

The reaction center chlorophylls a (Chla) of photosystem II (PSII) are composed of six Chla molecules including the special pair Chla P(D1)/P(D2) harbored by the D1/D2 heterodimer. They serve as the ultimate electron abstractors for water oxidation in the oxygen-evolving Mn(4)CaO(5) cluster. Using the PSII crystal structure analyzed at 1.9 Å resolution, the redox potentials of P(D1)/P(D2) for one-electron oxidation (E(m)) were calculated by considering all PSII subunits and the protonation pattern of all titratable residues. The E(m)(Chla) values were calculated to be 1015-1132 mV for P(D1) and 1141-1201 mV for P(D2), depending on the protonation state of the Mn(4)CaO(5) cluster. The results showed that E(m)(P(D1)) was lower than E(m)(P(D2)), favoring localization of the charge of the cationic state more on P(D1). The P(D1)(•+)/P(D2)(•+) charge ratio determined by the large-scale QM/MM calculations with the explicit PSII protein environment yielded a P(D1)(•+)/P(D2)(•+) ratio of ~80/~20, which was found to be due to the asymmetry in electrostatic characters of several conserved D1/D2 residue pairs that cause the E(m)(P(D1))/E(m)(P(D2)) difference, e.g., D1-Asn181/D2-Arg180, D1-Asn298/D2-Arg294, D1-Asp61/D2-His61, D1-Glu189/D2-Phe188, and D1-Asp170/D2-Phe169. The larger P(D1)(•+) population than P(D2)(•+) appears to be an inevitable fate of the intact PSII that possesses water oxidation activity.

DOI： 10.1021/ja203947k

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PubMed

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

Chloride binding in photosystem II (PSII) is essential for photosynthetic water oxidation. However, the functional roles of chloride and possible binding sites, during oxygen evolution, remain controversial. This paper examines the functions of chloride based on its binding site revealed in the X-ray crystal structure of PSII at 1.9 Å resolution. We find that chloride depletion induces formation of a salt bridge between D2-K317 and D1-D61 that could suppress the transfer of protons to the lumen.

DOI： 10.1021/bi200685w

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PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

We introduce a quantum mechanics/molecular mechanics model of the oxygen-evolving complex of photosystem II in the S(1) Mn(4)(IV,III,IV,III) state, where Ca(2+) is bridged to manganese centers by the carboxylate moieties of D170 and A344 on the basis of the new X-ray diffraction (XRD) model recently reported at 1.9 Å resolution. The model is also consistent with high-resolution spectroscopic data, including polarized extended X-ray absorption fine structure data of oriented single crystals. Our results provide refined intermetallic distances within the Mn cluster and suggest that the XRD model most likely corresponds to a mixture of oxidation states, including species more reduced than those observed in the catalytic cycle of water splitting.

DOI： 10.1021/bi200681q

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PubMed

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記述言語：英語  

DOI： 10.1016/j.jphotobiol.2011.03.017

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PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.cplett.2011.06.021

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/nature09913

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PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.cplett.2011.02.030

Web of Science

記述言語：英語  

DOI： 10.1016/j.bbabio.2010.12.013

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PubMed

記述言語：英語  

DOI： 10.1107/S0108767311081293

Web of Science

記述言語：英語   出版者・発行元：一般社団法人 日本生物物理学会  

DOI： 10.2142/biophys.51.S10_1

CiNii Research

記述言語：英語   出版者・発行元：一般社団法人 日本生物物理学会  

DOI： 10.2142/biophys.51.S95_2

記述言語：英語  

DOI： 10.1107/S0108767311081268

Web of Science

記述言語：英語  

DOI： 10.1107/S0108767311081256

Web of Science

記述言語：英語  

DOI： 10.1016/j.bbabio.2009.11.001

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PubMed

記述言語：英語  

DOI： 10.1107/S0108767310097291

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Proceedings of the National Academy of Sciences  

<jats:p>The chloride ion, Cl<jats:sup>−</jats:sup>, is an essential cofactor for oxygen evolution of photosystem II (PSII) and is closely associated with the Mn<jats:sub>4</jats:sub>Ca cluster. Its detailed location and function have not been identified, however. We substituted Cl<jats:sup>−</jats:sup>with a bromide ion (Br<jats:sup>−</jats:sup>) or an iodide ion (I<jats:sup>−</jats:sup>) in PSII and analyzed the crystal structures of PSII with Br<jats:sup>−</jats:sup>and I<jats:sup>−</jats:sup>substitutions. Substitution of Cl<jats:sup>−</jats:sup>with Br<jats:sup>−</jats:sup>did not inhibit oxygen evolution, whereas substitution of Cl<jats:sup>−</jats:sup>with I<jats:sup>−</jats:sup>completely inhibited oxygen evolution, indicating the efficient replacement of Cl<jats:sup>−</jats:sup>by I<jats:sup>−</jats:sup>. PSII with Br<jats:sup>−</jats:sup>and I<jats:sup>−</jats:sup>substitutions were crystallized, and their structures were analyzed. The results showed that there are 2 anion-binding sites in each PSII monomer; they are located on 2 sides of the Mn<jats:sub>4</jats:sub>Ca cluster at equal distances from the metal cluster. Anion-binding site 1 is close to the main chain of D1-Glu-333, and site 2 is close to the main chain of CP43-Glu-354; these 2 residues are coordinated directly with the Mn<jats:sub>4</jats:sub>Ca cluster. In addition, site 1 is located in the entrance of a proton exit channel. These results indicate that these 2 Cl<jats:sup>−</jats:sup>anions are required to maintain the coordination structure of the Mn<jats:sub>4</jats:sub>Ca cluster as well as the proposed proton channel, thereby keeping the oxygen-evolving complex fully active.</jats:p>

DOI： 10.1073/pnas.0812797106

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記述言語：英語  

DOI： 10.1016/j.bbabio.2008.11.004

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PubMed

記述言語：英語  

DOI： 10.1107/S0108767308090636

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.bbrc.2007.05.021

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PubMed

記述言語：英語  

DOI： 10.1039/c3cy00051f

Web of Science

記述言語：日本語   出版者・発行元：The Biophysical Society of Japan General Incorporated Association  

Photosystem II (PSII) is a membrane-protein complex consisting of 17 trans-membrane subunits and 3 peripheral, extrinsic subunits with a total molecular mass of 350 kDa for a monomer. PSII performs a series of light-induced electron transfer reactions, leading to the conversion of light energy into biologically useful chemical energy, coupled with this is the splitting of water and generation of molecular oxygen. Both the chemical energy converted and molecular oxygen generated by PSII are indispensible for sustaining life on the earth; thus PSII is an extremely important protein complex. We have succeeded in crystallizing the PSII complex at a resolution of 1.9 Å, and analyzed its structure. Here we describe the structure of PSII, in particular the Mn₄CaO₅-cluster, which is the catalytic center of water-splitting, analyzed at the atomic resolution. Based on these, we discuss the possible mechanisms of light-induced water-splitting and its implications in artificial photosynthesis.<br>

DOI： 10.2142/biophys.52.140

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その他リンク： https://jlc.jst.go.jp/DN/JALC/10000488562?from=CiNii

記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

CiNii Books

記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

CiNii Books

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

DOI： 10.1107/S0108767311098035

Web of Science

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

DOI： 10.1107/S0108767311081335

Web of Science

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

DOI： 10.1107/S0108767308092544

Web of Science

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

DOI： 10.1107/S0108767308089447

Web of Science

記述言語：日本語   出版者・発行元：日本ビタミン学会  

CiNii Books

記述言語：日本語  

光合成の水分解反応を行っている光化学系 II 蛋白質の活性中心 Mn₄CaO₅クラスターは III と IV 価の混合原子価状態と考えられているが、各 Mn の価数の議論はまだ結論がついていない。本研究は、Mn のX線吸収端が価数に応じてシフトすることに着目し、X線吸収に依存する異常分散項の電子密度差電子密度マップを用いて各Mnの価数を分析した。その結果、K-吸収端波長領域において、各 Mn の価数に応じた変化を明らかにした。

DOI： 10.18957/rr.8.1.1

CiNii Research

記述言語：日本語  

光合成で働く光化学系 II 蛋白質（PSII）の活性中心 Mn₄CaO₅ クラスターの Mn は III 価と IV 価と考えられているが、具体的な各 Mn の価数は議論中である。本研究では、Mn の K- 吸収端波長で測定した異常分散項の電子密度マップから価数の分析を計画した。しかし、不均一な厚みの結晶ではＸ線吸収が変動するため、異常分散項の測定精度が課題であった。本研究は、UV レーザー加工機によって PSII 結晶を円柱状に加工することで回折強度データを改善した報告である。

DOI： 10.18957/rr.9.4.177

CiNii Research

記述言語：日本語  

光合成における水分解反応を行う光化学系 II 蛋白質 (PSII) の反応機構の学理解明には、高分解能な結晶構造が不可欠である。本研究は、調湿ガスを使った脱水処理による PSII 結晶の改良を目指した。その結果、PSII 結晶は結晶格子が収縮し、それに伴って回折能が改善することが確認された。しかし、処理に時間を要することや収縮過程の再現性が難しいことなどの課題によって目標は達成されなかった。ただし、脱水収縮による改良の有益な情報は得られた。

DOI： 10.18957/rr.10.2.108

CiNii Research

記述言語：日本語  

DOI： 10.5940/jcrsj.54.247

CiNii Research

記述言語：日本語  

DOI： 10.11316/jpsgaiyo.66.1.2.0_378_2

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CiNii Research

Ycf12は近年、光化学系II複合体(PSII)のサブユニットであることが報告された低分子量膜貫通タンパク質であるが、その存在位置は不明である。我々は<I>Thermosynechococcus elongatus</I>(<I>T. elongatus</I>)のYcf12欠損株から、PSIIダイマーを精製し、結晶化し、X線結晶構造解析を行った。野生株PSIIとの差フーリエ電子密度から、Ycf12はPSIIの外縁部、PsbK、PsbZの近傍に位置することが判明した。これはベルリンのグループが報告した3.0Å分解能の構造において、未同定へリックスX1に対応する。この結果と我々がすでに報告したX2=PsbYの結果を考え合わせると、残る未同定のサブユニットX3はPsbXであることが推測された。また、我々はPsbZ欠損株よりPSIIダイマーを精製、結晶化したが、得られた結晶の格子定数が野生株のものと大きく異なっており、PsbZがPSII結晶中のダイマー同士の相互作用に関わっていることが示唆された。PsbZがYcf12のPSIIへの結合に必要であることは、PsbZ欠失株から精製したPSIIではYcf12とPsbKが脱落していることから示されたが、Ycf12欠失PSIIの結晶が野生株と同じ格子定数を持つことから、Ycf12はPSIIへのPSbZの結合に必要ないことが示唆された。

DOI： 10.14841/jspp.2009.0.0047.0

CiNii Research

記述言語：日本語  

DOI： 10.5940/jcrsj.63.24

CiNii Research

光化学系II複合体(PSII)の中心部分は原核生物から真核生物まで高度に保存されているが、酸素発生に必要な表在性タンパク質や低分子量サブユニットの一部は生物種によって異なっている。PSIIの立体構造は、原核生物であるラン色細菌由来のものについて報告されているが、真核生物由来のものについては報告されていない。紅藻は、原核生物に最も近い真核藻類の一つであり、その光化学系も、ラン色細菌と高等植物の間に移行している段階にあるといえる。紅藻PSIIには、20 kDaという、ラン色細菌に存在しない、4つ目の表在性タンパク質が結合しており、このような紅藻とラン色細菌のPSIIの構造上の違いを明らかにするためには紅藻PSIIの立体構造解析が必要である。そのため本研究では紅藻<I>Cyanidium caldarium</I>由来PSIIの結晶構造解析を目的として、PSIIの精製・結晶化を行っている。<I>C. caldarium</I>からPSIIの結晶を得たことはすでに昨年度の本大会で報告したが、分解能が低く構造解析が行えるまでには至っていなかった。今回、結晶の分解能を向上させるため結晶化条件の改良を行い、3.8Å分解能の回折データを得ることに成功したので、その詳細について報告する。なお、この結晶の回折データを用いて、現在紅藻PSIIの構造解析を進めている。

DOI： 10.14841/jspp.2008.0.0557.0

CiNii Research

PsbKとPsbZ は光化学系II複合体(PSII)を構成する低分子量サブユニットであり、ラン色細菌から高等植物まで広く保存されている。PsbKは分子量約4 kDa で1回膜貫通へリックスを持ち、PsbZは分子量約6 kDa で2回膜貫通へリックスを持っている。ラン色細菌PSIIの結晶構造において、両サブユニットはともに複合体の外縁部に存在し、CP43に近接している。これまでいくつかの生物種においてこれらサブユニットの欠失変異体を用いた機能解析が報告されているが、変異株の表現型は様々である。ラン色細菌では、これらサブユニットのいずれを欠いても光独立的に生育できることがわかっている。そこで我々は、これらサブユニットの機能を構造学的見地から明らかにするため好熱性ラン色細菌<I>Thermosynechococcus vulcanus</I> PsbK欠損株および<I>T. elongatus</I> PsbZ欠損株から、それぞれのPSIIを精製、結晶化し、結晶の性質をX線により調べた。その結果、いずれの変異株からも結晶を得ることに成功し、また、得られた結晶の格子定数は類似していたが、<I>T. vulcanus</I>野生株のPSII結晶の格子定数とは大きく異なっていた。従って、これらサブユニットの欠失が結晶格子内のPSII二量体間の相互作用に影響を及ぼしたことが示唆された。本発表ではPSIIの精製、結晶化法と結晶の性質について報告する。

DOI： 10.14841/jspp.2008.0.0559.0

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<jats:title>Abstract</jats:title>
<jats:p>In the present study, we report the electronic energy transfer (EET) rate and the EET dynamics in the hexamer of C-phycocyanin (C-PC). The EET rate for the Förster theory was calculated by a quantum chemical method and a master equation was used to describe the dynamics. Our calculation results suggest that the natural arrangements of phycocyanobilin (PCB) chromophores α84, β84, and β155 in C-PC are cooperatively well-adjusted to achieve the shortest EET time-length. It is the appropriate regular periodicity of the intermolecular distances and intermolecular angles of the ground and the first excited transition dipole moments of PCBs α84, β84, and β155, i.e., the three-fold symmetry and stacking order of their layers found in terrestrial plants and algae, that are some of the most important requisites in achieving such a highly efficient EET in PBS.</jats:p>

DOI： 10.1246/bcsj.20220334

CiNii Research

開催年月日： 2024年1月

記述言語：日本語   会議種別：ポスター発表  

開催年月日： 2023年11月

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催年月日： 2023年11月

記述言語：英語   会議種別：シンポジウム・ワークショップ パネル（指名）  

開催年月日： 2023年11月

記述言語：英語   会議種別：ポスター発表  

開催年月日： 2023年11月

記述言語：日本語   会議種別：ポスター発表  

開催年月日： 2023年11月

記述言語：日本語   会議種別：ポスター発表  

開催年月日： 2023年10月

記述言語：日本語   会議種別：ポスター発表  

開催年月日： 2023年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催年月日： 2023年7月

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催年月日： 2023年7月

記述言語：日本語   会議種別：ポスター発表  

開催年月日： 2023年1月

記述言語：日本語   会議種別：ポスター発表