Photosynthesis Research最新文献

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Adaptive significance of age- and light-related variation in needle structure, photochemistry, and pigments in evergreen coniferous trees. 常绿针叶树针叶结构、光化学和色素随年龄和光照变化的适应意义
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2025-02-01 Epub Date: 2024-12-20 DOI: 10.1007/s11120-024-01125-2
James Oluborode, Tamara Chadzinikolau, Magda Formela-Luboińska, Zi-Piao Ye, Piotr Robakowski
{"title":"Adaptive significance of age- and light-related variation in needle structure, photochemistry, and pigments in evergreen coniferous trees.","authors":"James Oluborode, Tamara Chadzinikolau, Magda Formela-Luboińska, Zi-Piao Ye, Piotr Robakowski","doi":"10.1007/s11120-024-01125-2","DOIUrl":"https://doi.org/10.1007/s11120-024-01125-2","url":null,"abstract":"<p><p>Evergreen conifers thrive in challenging environments by maintaining multiple sets of needles, optimizing photosynthesis even under harsh conditions. This study aimed to investigate the relationships between needle structure, photosynthetic parameters, and age along the light gradient in the crowns of Abies alba, Taxus baccata, and Picea abies. We hypothesized that: (1) Needle structure, photochemical parameters, and photosynthetic pigment content correlate with needle age and light levels in tree crowns. (2) The photosynthetic capacity of ageing needles would decline and adjust to the increasing self-shading of branches. Our results revealed a non-linear increase in the leaf mass-to-area ratio. The maximum quantum yield of photosystem II photochemistry decreased linearly with needle age without reaching levels indicative of photoinhibition. Decreased maximum electron transport rates (ETR<sub>max</sub>) were linked to declining values of saturating photosynthetic photon flux density and increasing non-photochemical quenching of fluorescence (NPQ), indicating energy losses as heat. The chlorophyll a to chlorophyll b ratio linearly decreased, suggesting older needles sustain high light capture efficiency. These findings offer new insights into the combined effects of needle ageing and self-shading on photochemistry and pigment content. This functional needle balance highlights the trade-off between the costs of long-term needle retention and the benefits of efficient resource utilization. In environments where air temperature is less of a constraint on photosynthesis due to climate warming, evergreen coniferous trees could sustain or enhance their photosynthetic capacity. They can achieve this by shortening needle lifespan and retaining fewer cohorts of needles with higher ETR<sub>max</sub> and lower NPQ compared to older needles.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 1","pages":"1-14"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142865127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Primary charge separation in Chloroflexus aurantiacus reaction centers at room temperature: ultrafast transient absorption measurements on QA-depleted preparations with native and chemically modified bacteriopheophytin composition.
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2025-02-01 Epub Date: 2024-12-19 DOI: 10.1007/s11120-024-01122-5
Alexey A Zabelin, Vyacheslav B Kovalev, Anton M Khristin, Ravil A Khatypov, Anatoly Ya Shkuropatov
{"title":"Primary charge separation in Chloroflexus aurantiacus reaction centers at room temperature: ultrafast transient absorption measurements on Q<sub>A</sub>-depleted preparations with native and chemically modified bacteriopheophytin composition.","authors":"Alexey A Zabelin, Vyacheslav B Kovalev, Anton M Khristin, Ravil A Khatypov, Anatoly Ya Shkuropatov","doi":"10.1007/s11120-024-01122-5","DOIUrl":"10.1007/s11120-024-01122-5","url":null,"abstract":"<p><p>The initial electron transfer (ET) processes in reaction centers (RCs) of Chloroflexus (Cfl.) aurantiacus were studied at 295 K using femtosecond transient absorption (TA) difference spectroscopy. Particular attention was paid to the decay kinetics of the primary electron donor excited state (P<sup>*</sup>) and the formation/decay of the absorption band of the monomeric bacteriochlorophyll a anion (B<sub>A</sub><sup>-</sup>) at ~ 1035 nm, which reflects the dynamics of the charge-separated state P<sup>+</sup>B<sub>A</sub><sup>-</sup>. It was found that in Q<sub>A</sub>-depleted RCs containing native bacteriopheophytin a (BPheo) molecules at the H<sub>A</sub> and H<sub>B</sub> binding sites, the decay of P<sup>*</sup> to form the P<sup>+</sup>H<sub>A</sub><sup>-</sup> state contains a fast (4 ps; relative amplitude 70%) and a slow (13 ps; relative amplitude 30%) kinetic components. The B<sub>A</sub><sup>-</sup> absorption band at ~ 1035 nm was detected only for the fast component. Based on global analysis of the TA data, the results are discussed in terms of the presence of two P<sup>*</sup> populations: in one, P<sup>*</sup> decays in 4 ps via a dominant two-step activationless P<sup>*</sup> → P<sup>+</sup>B<sub>A</sub><sup>-</sup> → P<sup>+</sup>H<sub>A</sub><sup>-</sup> ET with a contribution of 70% to the overall primary charge separation process, and in the other, P<sup>*</sup> decays in 13 ps via a one-step superexchange P<sup>*</sup> → P<sup>+</sup>H<sub>A</sub><sup>-</sup> ET (contribution of 30%). Similar femtosecond TA measurements on Q<sub>A</sub>-depleted-Pheo<sub>A</sub>-modified RCs, in which the charge separation energetics was changed by replacing BPheo H<sub>A</sub> with plant pheophytin a, suggest the presence of a P<sup>*</sup> population where P<sup>+</sup>H<sub>A</sub><sup>-</sup> formation can occur via a thermally activated two-step ET process.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 1","pages":"1-15"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142855098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Elucidating light-induced changes in excitation energy transfer of photosystem I and II in whole cells of two model cyanobacteria.
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2025-02-01 Epub Date: 2024-12-16 DOI: 10.1007/s11120-024-01124-3
Sandeep Biswas, Dariusz M Niedzwiedzki, Himadri B Pakrasi
{"title":"Elucidating light-induced changes in excitation energy transfer of photosystem I and II in whole cells of two model cyanobacteria.","authors":"Sandeep Biswas, Dariusz M Niedzwiedzki, Himadri B Pakrasi","doi":"10.1007/s11120-024-01124-3","DOIUrl":"10.1007/s11120-024-01124-3","url":null,"abstract":"<p><p>Excitation energy transfer between the photochemically active protein complexes is key for photosynthetic processes. Phototrophic organisms like cyanobacteria experience subtle changes in irradiance under natural conditions. Such changes need adjustments to the excitation energy transfer between the photosystems for sustainable growth. Spectroscopic assessments on purified photosystems usually fail to capture these subtle changes. In this study, we examined whole cells from two model cyanobacteria, Synechocystis sp. PCC 6803 and Synechococcus elongatus UTEX 2973, grown under high and low light conditions to decode the high light tolerance of the latter. This allowed us to study photosynthetic machinery in the native state and in this work we particularly focused on the excitation energy transfer within PSII and PSI manifold. Understanding the high-light tolerance mechanism is imperative as it can help design strategies for increasing the light tolerance of cyanobacteria used for carbon neutral bioproduction. Our observations suggest that Synechococcus 2973 employs an uncommon photoprotection strategy, and the absence of hydroxy-echinenone pigment in this strain opens the possibility of an orange carotenoid protein homolog utilizing zeaxanthin as a scavenger of reactive oxygen species to provide photoprotection. Furthermore, the adjustments to the high-light adaptation mechanism involve downregulating the phycobilisome antenna in Synechococcus 2973, but not in Synechocystis 6803. Additionally, the stoichiometric changes to PSII/PSI are more tightly regulated in Synechococcus 2973.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":" ","pages":"1-12"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142829713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Insights from Ca2+→Sr2+ substitution on the mechanism of O-O bond formation in photosystem II. Ca2+→Sr2+ 置换对光合系统 II 中 O-O 键形成机制的启示。
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2024-12-01 Epub Date: 2024-08-26 DOI: 10.1007/s11120-024-01117-2
Gabriel Bury, Yulia Pushkar
{"title":"Insights from Ca<sup>2+</sup>→Sr<sup>2+</sup> substitution on the mechanism of O-O bond formation in photosystem II.","authors":"Gabriel Bury, Yulia Pushkar","doi":"10.1007/s11120-024-01117-2","DOIUrl":"10.1007/s11120-024-01117-2","url":null,"abstract":"<p><p>In recent years, there has been a steady interest in unraveling the intricate mechanistic details of water oxidation mechanism in photosynthesis. Despite the substantial progress made over several decades, a comprehensive understanding of the precise kinetics underlying O-O bond formation and subsequent evolution remains elusive. However, it is well-established that the oxygen evolving complex (OEC), specifically the CaMn<sub>4</sub>O<sub>5</sub> cluster, plays a crucial role in O-O bond formation, undergoing a series of four oxidative events as it progresses through the S-states of the Kok cycle. To gain further insights into the OEC, researchers have explored the substitution of the Ca<sup>2+</sup> cofactor with strontium (Sr), the sole atomic replacement capable of retaining oxygen-evolving activity. Empirical investigations utilizing spectroscopic techniques such as XAS, XRD, EPR, FTIR, and XANES have been conducted to probe the structural consequences of Ca<sup>2+</sup>→Sr<sup>2+</sup> substitution. In parallel, the development of DFT and QM/MM computational models has explored different oxidation and protonation states, as well as variations in ligand coordination at the catalytic center involving amino acid residues. In this review, we critically evaluate and integrate these computational and spectroscopic approaches, focusing on the structural and mechanistic implications of Ca<sup>2+</sup>→Sr<sup>2+</sup> substitution in PS II. We contribute DFT modelling and simulate EXAFS Fourier transforms of Sr-substituted OEC, analyzing promising structures of the S<sub>3</sub> state. Through the combination of computational modeling and spectroscopic investigations, valuable insights have been gained, developing a deeper understanding of the photosynthetic process.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":" ","pages":"331-351"},"PeriodicalIF":2.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142056371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Phylogenetic and spectroscopic insights on the evolution of core antenna proteins in cyanobacteria. 蓝藻核心天线蛋白进化的系统发育和光谱见解。
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2024-12-01 Epub Date: 2023-09-22 DOI: 10.1007/s11120-023-01046-6
Sandeep Biswas, Dariusz M Niedzwiedzki, Michelle Liberton, Himadri B Pakrasi
{"title":"Phylogenetic and spectroscopic insights on the evolution of core antenna proteins in cyanobacteria.","authors":"Sandeep Biswas, Dariusz M Niedzwiedzki, Michelle Liberton, Himadri B Pakrasi","doi":"10.1007/s11120-023-01046-6","DOIUrl":"10.1007/s11120-023-01046-6","url":null,"abstract":"<p><p>Light harvesting by antenna systems is the initial step in a series of electron-transfer reactions in all photosynthetic organisms, leading to energy trapping by reaction center proteins. Cyanobacteria are an ecologically diverse group and are the simplest organisms capable of oxygenic photosynthesis. The primary light-harvesting antenna in cyanobacteria is the large membrane extrinsic pigment-protein complex called the phycobilisome. In addition, cyanobacteria have also evolved specialized membrane-intrinsic chlorophyll-binding antenna proteins that transfer excitation energy to the reaction centers of photosystems I and II (PSI and PSII) and dissipate excess energy through nonphotochemical quenching. Primary among these are the CP43 and CP47 proteins of PSII, but in addition, some cyanobacteria also use IsiA and the prochlorophyte chlorophyll a/b binding (Pcb) family of proteins. Together, these proteins comprise the CP43 family of proteins owing to their sequence similarity with CP43. In this article, we have revisited the evolution of these chlorophyll-binding antenna proteins by examining their protein sequences in parallel with their spectral properties. Our phylogenetic and spectroscopic analyses support the idea of a common ancestor for CP43, IsiA, and Pcb proteins, and suggest that PcbC might be a distant ancestor of IsiA. The similar spectral properties of CP47 and IsiA suggest a closer evolutionary relationship between these proteins compared to CP43.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":" ","pages":"197-210"},"PeriodicalIF":2.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41130298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Perspectives of cyanobacterial cell factories. 蓝藻细胞工厂的前景。
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2024-12-01 Epub Date: 2023-11-15 DOI: 10.1007/s11120-023-01056-4
Anastasios Melis, Diego Alberto Hidalgo Martinez, Nico Betterle
{"title":"Perspectives of cyanobacterial cell factories.","authors":"Anastasios Melis, Diego Alberto Hidalgo Martinez, Nico Betterle","doi":"10.1007/s11120-023-01056-4","DOIUrl":"10.1007/s11120-023-01056-4","url":null,"abstract":"<p><p>Cyanobacteria are prokaryotic photosynthetic microorganisms that can generate, in addition to biomass, useful chemicals and proteins/enzymes, essentially from sunlight, carbon dioxide, and water. Selected aspects of cyanobacterial production (isoprenoids and high-value proteins) and scale-up methods suitable for product generation and downstream processing are addressed in this review. The work focuses on the challenge and promise of specialty chemicals and proteins production, with isoprenoid products and biopharma proteins as study cases, and the challenges encountered in the expression of recombinant proteins/enzymes, which underline the essence of synthetic biology with these microorganisms. Progress and the current state-of-the-art in these targeted topics are emphasized.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":" ","pages":"459-471"},"PeriodicalIF":2.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11615099/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"107592025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Exceptional Quantum Efficiency Powers Biomass Production in Halotolerant Algae Picochlorum sp. 耐盐藻类 Picochlorum sp.
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2024-12-01 Epub Date: 2024-02-08 DOI: 10.1007/s11120-024-01075-9
Colin Gates, Gennady Ananyev, Fatima Foflonker, Debashish Bhattacharya, G Charles Dismukes
{"title":"Exceptional Quantum Efficiency Powers Biomass Production in Halotolerant Algae Picochlorum sp.<sup />","authors":"Colin Gates, Gennady Ananyev, Fatima Foflonker, Debashish Bhattacharya, G Charles Dismukes","doi":"10.1007/s11120-024-01075-9","DOIUrl":"10.1007/s11120-024-01075-9","url":null,"abstract":"<p><p>The green algal genus Picochlorum is of biotechnological interest because of its robust response to multiple environmental stresses. We compared the metabolic performance of P. SE3 and P. oklahomense to diverse microbial phototrophs and observed exceptional performance of photosystem II (PSII) in light energy conversion in both Picochlorum species. The quantum yield (QY) for O<sub>2</sub> evolution is the highest of any phototroph yet observed, 32% (20%) by P. SE3 (P. okl) when normalized to total PSII subunit PsbA (D1) protein, and 80% (75%) normalized per active PSII, respectively. Three factors contribute: (1) an efficient water oxidizing complex (WOC) with the fewest photochemical misses of any organism; (2) faster reoxidation of reduced (PQH<sub>2</sub>)<sub>B</sub> in P. SE3 than in P. okl. (period-2 Fourier amplitude); and (3) rapid reoxidation of the plastoquinol pool by downstream electron carriers (Cyt b<sub>6</sub>f/PETC) that regenerates PQ faster in P. SE3. This performance gain is achieved without significant residue changes around the Q<sub>B</sub> site and thus points to a pull mechanism involving faster PQH<sub>2</sub> reoxidation by Cyt b<sub>6</sub>f/PETC that offsets charge recombination. This high flux in P. SE3 may be explained by genomically encoded plastoquinol terminal oxidases 1 and 2, whereas P. oklahomense has neither. Our results suggest two distinct types of PSII centers exist, one specializing in linear electron flow and the other in PSII-cyclic electron flow. Several amino acids within D1 differ from those in the low-light-descended D1 sequences conserved in Viridiplantae, and more closely match those in cyanobacterial high-light D1 isoforms, including changes near tyrosine Y<sub>z</sub> and a water/proton channel near the WOC. These residue changes may contribute to the exceptional performance of Picochlorum at high-light intensities by increasing the water oxidation efficiency and the electron/proton flux through the PSII acceptors (Q<sub>A</sub>Q<sub>B</sub>).</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":" ","pages":"439-457"},"PeriodicalIF":2.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139703166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Macroscale structural changes of thylakoid architecture during high light acclimation in Chlamydomonas reinhardtii. 莱茵衣藻在强光适应过程中的类囊体结构的宏观变化
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2024-12-01 Epub Date: 2024-01-05 DOI: 10.1007/s11120-023-01067-1
Mimi Broderson, Krishna K Niyogi, Masakazu Iwai
{"title":"Macroscale structural changes of thylakoid architecture during high light acclimation in Chlamydomonas reinhardtii.","authors":"Mimi Broderson, Krishna K Niyogi, Masakazu Iwai","doi":"10.1007/s11120-023-01067-1","DOIUrl":"10.1007/s11120-023-01067-1","url":null,"abstract":"<p><p>Photoprotection mechanisms are ubiquitous among photosynthetic organisms. The photoprotection capacity of the green alga Chlamydomonas reinhardtii is correlated with protein levels of stress-related light-harvesting complex (LHCSR) proteins, which are strongly induced by high light (HL). However, the dynamic response of overall thylakoid structure during acclimation to growth in HL has not been fully understood. Here, we combined live-cell super-resolution microscopy and analytical membrane subfractionation to investigate macroscale structural changes of thylakoid membranes during HL acclimation in Chlamydomonas. Subdiffraction-resolution live-cell imaging revealed that the overall thylakoid structures became thinned and shrunken during HL acclimation. The stromal space around the pyrenoid also became enlarged. Analytical density-dependent membrane fractionation indicated that the structural changes were partly a consequence of membrane unstacking. The analysis of both an LHCSR loss-of-function mutant, npq4 lhcsr1, and a regulatory mutant that over-expresses LHCSR, spa1-1, showed that structural changes occurred independently of LHCSR protein levels, demonstrating that LHCSR was neither necessary nor sufficient to induce the thylakoid structural changes associated with HL acclimation. In contrast, stt7-9, a mutant lacking a kinase of major light-harvesting antenna proteins, had a slower thylakoid structural response to HL relative to all other lines tested but still showed membrane unstacking. These results indicate that neither LHCSR- nor antenna-phosphorylation-dependent HL acclimation are required for the observed macroscale structural changes of thylakoid membranes in HL conditions.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":" ","pages":"427-437"},"PeriodicalIF":2.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11614958/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139098510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Theoretical elucidation of the structure, bonding, and reactivity of the CaMn4Ox clusters in the whole Kok cycle for water oxidation embedded in the oxygen evolving center of photosystem II. New molecular and quantum insights into the mechanism of the O-O bond formation. CaMn4Ox团簇在整个Kok循环中的结构、键合和反应性的理论阐明,用于嵌入光系统II的析氧中心的水氧化。对O-O键形成机制的新的分子和量子见解。
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2024-12-01 Epub Date: 2023-11-09 DOI: 10.1007/s11120-023-01053-7
Kizashi Yamaguchi, Koichi Miyagawa, Mitsuo Shoji, Takashi Kawakami, Hiroshi Isobe, Shusuke Yamanaka, Takahito Nakajima
{"title":"Theoretical elucidation of the structure, bonding, and reactivity of the CaMn<sub>4</sub>O<sub>x</sub> clusters in the whole Kok cycle for water oxidation embedded in the oxygen evolving center of photosystem II. New molecular and quantum insights into the mechanism of the O-O bond formation.","authors":"Kizashi Yamaguchi, Koichi Miyagawa, Mitsuo Shoji, Takashi Kawakami, Hiroshi Isobe, Shusuke Yamanaka, Takahito Nakajima","doi":"10.1007/s11120-023-01053-7","DOIUrl":"10.1007/s11120-023-01053-7","url":null,"abstract":"<p><p>This paper reviews our historical developments of broken-symmetry (BS) and beyond BS methods that are applicable for theoretical investigations of metalloenzymes such as OEC in PSII. The BS hybrid DFT (HDFT) calculations starting from high-resolution (HR) XRD structure in the most stable S<sub>1</sub> state have been performed to elucidate structure and bonding of whole possible intermediates of the CaMn<sub>4</sub>O<sub>x</sub> cluster (1) in the S<sub>i</sub> (i = 0 ~ 4) states of the Kok cycle. The large-scale HDFT/MM computations starting from HR XRD have been performed to elucidate biomolecular system structures which are crucial for examination of possible water inlet and proton release pathways for water oxidation in OEC of PSII. DLPNO CCSD(T<sub>0</sub>) computations have been performed for elucidation of scope and reliability of relative energies among the intermediates by HDFT. These computations combined with EXAFS, XRD, XFEL, and EPR experimental results have elucidated the structure, bonding, and reactivity of the key intermediates, which are indispensable for understanding and explanation of the mechanism of water oxidation in OEC of PSII. Interplay between theory and experiments have elucidated important roles of four degrees of freedom, spin, charge, orbital, and nuclear motion for understanding and explanation of the chemical reactivity of 1 embedded in protein matrix, indicating the participations of the Ca(H<sub>2</sub>O)<sub>n</sub> ion and tyrosine(Yz)-O radical as a one-electron acceptor for the O-O bond formation. The Ca-assisted Y<sub>z</sub>-coupled O-O bond formation mechanisms for water oxidation are consistent with recent XES and very recent time-resolved SFX XFEL and FTIR results.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":" ","pages":"291-330"},"PeriodicalIF":2.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11614991/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72015057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Crystallographic and biochemical analyses of a far-red allophycocyanin to address the mechanism of the super-red-shift. 对一种远红异藻花青素进行晶体学和生物化学分析,以解决超红移的机制问题。
IF 2.9 3区 生物学
Photosynthesis Research Pub Date : 2024-12-01 Epub Date: 2024-01-06 DOI: 10.1007/s11120-023-01066-2
Li-Juan Zhou, Astrid Höppner, Yi-Qing Wang, Jian-Yun Hou, Hugo Scheer, Kai-Hong Zhao
{"title":"Crystallographic and biochemical analyses of a far-red allophycocyanin to address the mechanism of the super-red-shift.","authors":"Li-Juan Zhou, Astrid Höppner, Yi-Qing Wang, Jian-Yun Hou, Hugo Scheer, Kai-Hong Zhao","doi":"10.1007/s11120-023-01066-2","DOIUrl":"10.1007/s11120-023-01066-2","url":null,"abstract":"<p><p>Far-red absorbing allophycocyanins (APC), identified in cyanobacteria capable of FRL photoacclimation (FaRLiP) and low-light photoacclimation (LoLiP), absorb far-red light, functioning in energy transfer as light-harvesting proteins. We report an optimized method to obtain high purity far-red absorbing allophycocyanin B, AP-B2, of Chroococcidiopsis thermalis sp. PCC7203 by synthesis in Escherichia coli and an improved purification protocol. The crystal structure of the trimer, (PCB-ApcD5/PCB-ApcB2)<sub>3</sub>, has been resolved to 2.8 Å. The main difference to conventional APCs absorbing in the 650-670 nm range is a largely flat chromophore with the co-planarity extending, in particular, from rings BCD to ring A. This effectively extends the conjugation system of PCB and contributes to the super-red-shifted absorption of the α-subunit (λ<sub>max</sub> = 697 nm). On complexation with the β-subunit, it is even further red-shifted (λ<sub>max, absorption</sub> = 707 nm, λ<sub>max, emission</sub> = 721 nm). The relevance of ring A for this shift is supported by mutagenesis data. A variant of the α-subunit, I123M, has been generated that shows an intense FR-band already in the absence of the β-subunit, a possible model is discussed. Two additional mechanisms are known to red-shift the chromophore spectrum: lactam-lactim tautomerism and deprotonation of the chromophore that both mechanisms appear inconsistent with our data, leaving this question unresolved.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":" ","pages":"171-185"},"PeriodicalIF":2.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139106414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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