Photosynthesis Research最新文献

{"title":"Canthaxanthin substitution of β-carotene yields structurally stable yet spectrally robust photosystem I cores in Synechocystis sp. PCC 6803.","authors":"Takanori A Fukasawa, Yoshifumi Ueno, Masahiko Ikeuchi, Tatsuya Tomo, Ryo Nagao","doi":"10.1007/s11120-026-01200-w","DOIUrl":"10.1007/s11120-026-01200-w","url":null,"abstract":"<p><p>Carotenoids (Cars) are essential cofactors in photosystem I (PSI), where they stabilize the pigment-protein framework and support excitation-energy transfer and photoprotection. Although metabolic engineering has enabled the production of diverse keto-carotenoids (keto-Cars) across oxyphototrophs, the structural and photophysical consequences of installing a single engineered Car into purified PSI cores remain unclear. Here, we generated a Synechocystis sp. PCC 6803 strain expressing only the crtW gene (CrtW strain), which converts β-carotene to canthaxanthin, and isolated PSI trimers to evaluate how extensive β-carotene substitution influences PSI organization and photophysical properties. HPLC analysis showed no detectable β-carotene in the CrtW PSI, indicating that it was largely replaced by canthaxanthin together with a minor unidentified Car. SDS-PAGE and BN-PAGE showed that the polypeptide composition and trimeric architecture of the CrtW PSI were indistinguishable from those of the control complex. Room-temperature absorption spectra revealed pronounced Car-dependent differences between 450 and 570 nm, consistent with the altered pigment composition, whereas the chlorophyll (Chl) Qy band remained unchanged. Notably, 77-K fluorescence-emission profiles of the CrtW PSI overlapped almost perfectly with those of the control regardless of excitation wavelength, suggesting that the organization of the low-energy Chl network is preserved. These findings indicate that cyanobacterial PSI trimers can assemble and maintain photophysical integrity with canthaxanthin in place of β-carotene without perturbing their oligomeric organization. The CrtW PSI thus provides a clean and tractable platform for dissecting how Car chemical features shape pigment-protein interactions and for guiding rational pigment redesign in photosynthetic complexes.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 2","pages":""},"PeriodicalIF":3.8,"publicationDate":"2026-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147284856","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}

{"title":"Correction to: Estimating the redox state of the plastoquinone pool in algae and cyanobacteria via OJIP fluorescence: perspectives and limitations.","authors":"Tomáš Zavřel, Anne-Christin Pohland, Tobias Pfennig, Anna Barbara Matuszyńska, Szilvia Z Tóth, Gábor Bernát, Jan Červený","doi":"10.1007/s11120-026-01203-7","DOIUrl":"10.1007/s11120-026-01203-7","url":null,"abstract":"","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 2","pages":"14"},"PeriodicalIF":3.8,"publicationDate":"2026-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12909315/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146202526","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}

{"title":"Heterogeneity within phycobilisomes is highly orchestrated.","authors":"Jaspreet K Sound, Maayan Suissa Szlejf, Hannah E Wedgwood, Noam Adir, Aneika C Leney","doi":"10.1007/s11120-026-01202-8","DOIUrl":"10.1007/s11120-026-01202-8","url":null,"abstract":"<p><p>The phycobilisome (PBS) is one of the oldest and most efficient light-harvesting protein complexes known. Throughout billions of years of evolution, the PBS has readily adapted to its environment through differential gene expression alongside controlled assembly/disassembly of its components. How hundreds of protein subunits assemble in a controlled manner into different PBS structures within different cyanobacterial species is unknown. Moreover, PBSs are not static entities, and can have different compositions that enables them to modulate their overall function in response to changes in their environment. Here, we utilised high resolving native mass spectrometry (MS) to probe the heterogeneity within PBSs and determine factors that govern its self-assembly. By monitoring PBSs stable sub-complexes, we were able to detect low abundant allophycocyanin variants ApcD and ApcF, in addition to the core linker protein ApcC, and determine their complex stoichiometry. Furthermore, native MS revealed the phycobiliproteins, phycocyanin and allophycocyanin, are unable to form mixed rings within the PBS structure, and instead can only stack, one on of top of another, for efficient energy transfer. Finally, we show that in strains such as A. marina where no allophycocyanin core is present, phycocyanin variants acts as distinct entities to ensure highly orchestrated PBS assembly. Together, the methodology and data obtained open up new avenues for future exploration into how the PBS adapts for effective function.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 1","pages":"13"},"PeriodicalIF":3.8,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12883523/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146143225","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}

{"title":"Different efficiency of Orange Carotenoid Protein (OCP)-related quenching during high light regulation of two cyanobacterial species.","authors":"Kui Xu, Shiquan Tang, Chun Chen, Yong Zhang, Zhengke Li, Zhen Chen, Weizhi Li, Xiongwen Chen, Philippe Juneau","doi":"10.1007/s11120-026-01201-9","DOIUrl":"10.1007/s11120-026-01201-9","url":null,"abstract":"<p><p>The mechanisms of high light regulation in cyanobacteria play a vital role in allowing cyanobacteria to cope with high light stress. Orange Carotenoid Protein (OCP)-related quenching is the primary regulatory response to high light and has been extensively studied in the cyanobacterium Synechocystis sp. PCC6803 (hereafter Synechocystis sp.). However, the difference in the efficiency of this OCP-related quenching for optimal regulation of high light is still unclear among different cyanobacterial species. Therefore, we evaluated the efficiency of the OCP-related quenching mechanisms in Synechocystis sp. and Microcystis aeruginosa FACHB905 (hereafter M. aeruginosa). We found that M. aeruginosa had higher OCP-related quenching than Synechocystis sp. under high light stress. Interestingly, M. aeruginosa also showed faster OCP-related quenching under high light and faster recovery of OCP-related quenching when high light was turned off, compared to Synechocystis sp. Moreover, M. aeruginosa showed a higher ability to regulate high light stress than Synechocystis sp., suggesting that OCP-related quenching is more efficient in M. aeruginosa than in Synechocystis sp., permitting the former to cope with high light stress. The tertiary structures of OCP in Synechocystis sp. and M. aeruginosa demonstrate structural variations based on key amino acid substitution that may be responsible for the observed differences in the efficiency of OCP. These results suggest that OCP could have different structures with varied key amino acids, providing cyanobacteria with varied efficiencies to adapt to their environment.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 1","pages":"12"},"PeriodicalIF":3.8,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146086557","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}

{"title":"The role of far-red fluorescing chlorophylls in the quenching of LHCII.","authors":"Václav Šebelík, Alexander Paradzah, David Bína, Dan-Hong Li, Valentyna Kuznetsova, Alexander Ruban, Tomáš Polívka","doi":"10.1007/s11120-026-01199-0","DOIUrl":"10.1007/s11120-026-01199-0","url":null,"abstract":"<p><p>In photosynthetic organisms, the major light-harvesting antenna protein LHCII performs the dual function of capturing excitation energy and protecting the photosystem from over-excitation via non-photochemical quenching (NPQ). We investigated the role of far-red-fluorescing chlorophylls (emission > 700 nm) in quenching LHCII by comparing isolated trimeric LHCII (denoted F680) with aggregated LHCII prepared in a glycerol-rich medium (denoted F730). Time-resolved fluorescence and ultrafast transient-absorption spectroscopy, including an intensity-cycling scheme to separate annihilation-free dynamics, were used. We find that the red-emissive chlorophyll states are populated in < 100 ps and display properties consistent with states having a low transition-dipole moment. Despite the significant shortening of the chlorophyll-a excited-state lifetimes in the F730 sample (hundreds of picoseconds vs. several nanoseconds in F680), no long-lived excited-state species attributable to the far-red emitters were detected in the transient-absorption data. These findings suggest that the far-red-fluorescing chlorophylls are not the direct quenchers but rather markers of the quenched LHCII configuration and highlight the necessity to better define aggregate size and internal organization for elucidating the molecular mechanism of quenching.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 1","pages":"11"},"PeriodicalIF":3.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12855284/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146086517","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}

{"title":"Preparative isolation and preliminary characterization of LHCII trimers and PSII monomers from Posidonia oceanica L.","authors":"Stefano Francesco Farci, Luca Iesu, Domenica Farci, Dario Piano","doi":"10.1007/s11120-026-01196-3","DOIUrl":"10.1007/s11120-026-01196-3","url":null,"abstract":"<p><p>Posidonia oceanica L. is a vascular marine plant that represents a relevant case study in plant physiology due to its phylogenetic position, ecological adaptations, and, in particular, the specialization of its photosynthetic apparatus. Here, we present a procedure for fractional thylakoid solubilization, in which a crude leaf extract obtained by blending is preliminarily depleted of the polyphenolic fraction and subsequently subjected to stepwise solubilization. The resulting thylakoid extracts, processed through a chromatographic workflow, enable the preparative isolation of trimeric Light-Harvesting Complex II and monomeric Photosystem II core complex. Protein identification was supported by mass spectrometry, with peptide homology analysis used for the assignment due to the absence of a curated proteome for P. oceanica. The resulting fractions enable downstream characterization, establishing the first chromatography-based preparative workflow for functional and structural investigations of the photosynthetic apparatus of this ecologically unique species.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 1","pages":"10"},"PeriodicalIF":3.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12855319/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146086486","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}

{"title":"Light harvesting mechanism of the multi-pigment reaction center with three chlorophyll species adapted to both visible and far-red light.","authors":"Wataru Shimooka, Hirotaka Kitoh-Nishioka, Shigeru Itoh, Akihiro Kimura","doi":"10.1007/s11120-026-01198-1","DOIUrl":"10.1007/s11120-026-01198-1","url":null,"abstract":"<p><p>We studied functions of a unique type-I photosynthetic reaction center complex containing three different types of chlorophyll species: bacteriochlorophyll a (BChl a), Zn-bacteriochlorophyll aʹ (Zn-BChl aʹ), and chlorophyll a (Chl a), adapted to both visible and far-red light environments, of an Acidobacterium Chloracidobacterium thermophilum reaction center (CabRC). The RC contains altogether 16 BChl a, 10 Chl a, the two molecules of Zn-BChl aʹ that form a special pair, and two lycopenes. We analyzed the excitation energy transfer (EET) dynamics on CabRC by calculating exciton Hamiltonians of all the pigments based on the structural information by using the modified Redfield theory. EET rates were predicted to be slower between Chls a and BChls a, compared to that between Chls a or between BChls a. The slow EET between exciton bands of 10 Chls a and 16 BChls a, thus, limits the overall efficiency of EET, although it is significantly enhanced by the intramolecular vibrational modes in the exciton-phonon interaction. The usage of multiple pigment species, therefore, allows the efficient usage of energy of a wide range of visible to far-red light in CabRC, which provides the highly optimized arrangements of heterogeneous pigments.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 1","pages":"8"},"PeriodicalIF":3.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12852291/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146093804","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}

{"title":"Charge reversal at the Lhcb2 N-terminus impairs phosphorylation and PSI-LHCII complex formation.","authors":"Akanksha Srivastava, Christo Schiphorst, Jarne Berentsen, Dana Verhoeven, Jan van Leeuwen, Fiamma Longoni, Francesco Saccon, Emilie Wientjes","doi":"10.1007/s11120-026-01197-2","DOIUrl":"10.1007/s11120-026-01197-2","url":null,"abstract":"<p><p>State transitions balance excitation-energy distribution between Photosystem I and Photosystem II in higher plants. Stn7-mediated phosphorylation of the N-terminus of the light-harvesting complex II protein Lhcb2 plays a central role in photosynthetic state transitions. However, it remains unclear how the intrinsic charge of this region, independent of its phosphorylation status, influences state transitions and thylakoid membrane organization. Here, we introduced specific charge-altering mutations in the Lhcb2 N-terminus of Arabidopsis thaliana in the lhcb2 knock-out background and analyzed their effects on LHCII phosphorylation, state transition dynamics, PSI–LHCII complex formation, and thylakoid ultrastructure. Substitution of a conserved positively charged arginine with a negatively charged glutamate (R2E) markedly reduced Lhcb1 and Lhcb2 phosphorylation and state transition efficiency, and abolished PSI–LHCII complex formation. In contrast, introducing a negative charge at a downstream position (Q9E) had no detectable effects. Electron microscopy revealed no significant changes in thylakoid organization in either mutant compared to WT Lhcb2 plants. Despite strongly reduced Lhcb1 and Lhcb2 phosphorylation in the R2E mutant, residual state transitions persisted, potentially mediated by Stn7-dependent phosphorylation of other target proteins. Together, these results provide insight into the role of N-terminal LHCII electrostatics in state transitions and thylakoid membrane organization in plants.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 1","pages":"9"},"PeriodicalIF":3.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12852261/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146093816","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}

{"title":"Correction to: Singular adaptations in the carbon assimilation mechanism of the polyextremophile cyanobacterium Chroococcidiopsis thermalis.","authors":"Pere Aguiló-Nicolau, Jeroni Galmés, Giacomo Fais, Sebastià Capó-Bauçà, Giacomo Cao, Concepción Íñiguez","doi":"10.1007/s11120-025-01185-y","DOIUrl":"10.1007/s11120-025-01185-y","url":null,"abstract":"","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 1","pages":"7"},"PeriodicalIF":3.7,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12827293/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146019074","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}

{"title":"Estimating the redox state of the plastoquinone pool in algae and cyanobacteria via OJIP fluorescence: perspectives and limitations.","authors":"Tomáš Zavřel, Anne-Christin Pohland, Tobias Pfennig, Anna Barbara Matuszyńska, Szilvia Z Tóth, Gábor Bernát, Jan Červený","doi":"10.1007/s11120-025-01194-x","DOIUrl":"10.1007/s11120-025-01194-x","url":null,"abstract":"<p><p>The redox state of the plastoquinone pool (PQ-redox) acts as a central element in a variety of intracellular signal pathways. Several methods for determining PQ-redox have been established. Although some of these methods are quantitative, such as those based on liquid chromatography, they are typically sensitive to sample preparation. Here, we critically evaluate the use of fast chlorophyll a fluorescence induction kinetics (the so-called OJIP transient) for semi-quantitative PQ-redox estimation in green algae (Chlorella vulgaris) and cyanobacteria (Synechocystis sp. PCC 6803). The method, based on the evaluation of relative fluorescence yield at the J-step of the OJIP transient (VJ, VJ’), has already been reported; however, thus far, it has been used mostly for studying dark-acclimated leaves, which limits its range of application. Here, we show that the OJIP transient can be used for semi-quantitative estimation of PQ-redox in algal and cyanobacterial cell cultures, in addition to plants. We further show that it can reflect PQ-redox in both dark-acclimated and light-acclimated samples. Our systematic comparison of Multi-Color PAM, AquaPen, and FL 6000 fluorometers demonstrates that accurate measurement of VJ and VJ’ parameters in suspension cultures requires low culture density and a high-intensity saturation pulse. We further show that with increasing light intensity to which the cells are exposed, the state of photosystem II (PSII) changes due to light-induced reduction of quinone A (QA−) and conformational changes, which in turn influence both the sensitivity and dynamic range of the VJ’ parameter towards PQ-redox estimation. A comparison of fluorescence transients in Chlorella and Synechocystis revealed relatively narrow range of PQ-redox states across diverse conditions in Synechocystis, maintained by terminal oxidases present at the thylakoid membrane. While we discuss certain limitations, our systematic assessment suggests that the OJIP method has great potential to become a routine tool for semi-quantitative PQ-redox estimation under a wide range of experimental conditions in green algae and cyanobacteria.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"164 1","pages":"6"},"PeriodicalIF":3.8,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12816086/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145998684","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}