Photosynthesis Research最新文献

{"title":"Calculation of specificity constants Γ for RUBISCO of different species from microcalorimetric data.","authors":"Joachim Frank, Frank Müh","doi":"10.1007/s11120-025-01187-w","DOIUrl":"10.1007/s11120-025-01187-w","url":null,"abstract":"<p><p>Based on earlier data concerning the reaction enthalpy [Formula: see text] of Ribulose 1,5-bisphosphate carboxylase/oxygenase (RUBISCO) from spinach (Frank et al. Phys Chem Chem Phys 2:1301-1304, 2000), it is shown that the specificity constant [Formula: see text], indicating the ability of RUBISCO to discriminate between CO₂ and O₂ as substrate, can be determined from an isothermal titration calorimetric (ITC) measurement of [Formula: see text] as a function of the substrate concentration ratio [Formula: see text]. The approach does not need any radioactive materials and might be a cost-effective alternative for RUBISCO engineering to screen for variants with a high specificity constant.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"63"},"PeriodicalIF":3.8,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12669348/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145649061","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":"Excitation energy transfer and trapping in Photosystem I of the green alga Bryopsis corticulans.","authors":"Parveen Akhtar, Wenda Wang, Sumit Singhal, Ferenc Sarlós, Jian-Ren Shen, Petar H Lambrev","doi":"10.1007/s11120-025-01181-2","DOIUrl":"10.1007/s11120-025-01181-2","url":null,"abstract":"<p><p>Photosystem I (PSI) from the siphonous green alga Bryopsis corticulans carries ten subunits of Light-Harvesting Complex I (LHCI) that enlarge its absorption cross-section yet must still deliver excitations rapidly to the P₇₀₀ reaction center. Here we investigate the light-harvesting function of PSI-LHCI, the excitation energy transfer within the supercomplex and how it affects the overall photochemical trapping lifetime. We performed picosecond time-resolved fluorescence spectroscopy at room temperature and 77 K and femtosecond transient absorption spectroscopy on purified PSI-LHCI supercomplex. Ultrafast spectroscopy showed that spectral equilibration in the antenna occurs mainly in the first 1 ps after excitation and is virtually complete within 10 ps. Nonetheless, the fluorescence lifetime of the supercomplex was 49-55 (±1) ps, depending on excitation wavelength, compared to 22 ps in the core complex. This result suggests that energy transfer continues over tens of ps, long after thermal equilibration between high- and low-energy excited states. The fluorescence analysis suggests that two factors contribute to the increased excitation lifetime - a thermodynamic factor, directly stemming from the increased antenna size as well as a kinetic factor, i.e. a rate limitation of trapping imposed by the energy transfer from LHCI to PSI. The average time of excitation transfer from LHCI to the reaction center was estimated to be close to 30 ps. Therefore, energy transfer from the enlarged antenna does not impose a sizeable kinetic limitation to the photochemical quantum efficiency of the photosystem.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"62"},"PeriodicalIF":3.8,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12644198/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145588474","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":"Changes in light-harvesting and energy-transfer processes of the chlorophyll d-dominated cyanobacterium Acaryochloris marina in response to different light qualities.","authors":"Zhe Wang, Yoshifumi Ueno, Reona Toyofuku, Tatsuya Tomo, Seiji Akimoto","doi":"10.1007/s11120-025-01182-1","DOIUrl":"10.1007/s11120-025-01182-1","url":null,"abstract":"<p><p>Acaryochloris marina (A. marina) is a distinctive cyanobacterium that contains rod-shaped phycobiliproteins (PBPs) and uses chlorophyll (Chl) d as its principal photosynthetic pigment, enabling it to absorb far-red light for photosynthesis. Under varying environmental light conditions, several cyanobacteria have been reported to exhibit decreased PBP content under red light and increased levels under green light. For A. marina, a reduction in PBP has also been observed under red and far-red light. However, the changes in light-harvesting and energy-transfer processes of A. marina in response to different light qualities remain insufficiently characterized. In the present study, A. marina cells were cultured under white, blue, green, yellow, red, or far-red LEDs. Compared with cultures grown under white-LEDs, blue-, red-, and far-red-LED-grown cells showed a decrease in the PBP/Chl d ratio, whereas green- and yellow-LED-grown cells showed an increase. The energy-transfer process of green-LED-grown cells at 77 K exhibited pronounced alterations in photosystem II. Based on these findings, we discuss the variations in light-harvesting and energy-transfer processes of A. marina under different light conditions.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"60"},"PeriodicalIF":3.8,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145541884","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":"Energy transfers between the B850 antennas: hybrid hierarchical equation approach.","authors":"Vladimir I Novoderezhkin","doi":"10.1007/s11120-025-01184-z","DOIUrl":"10.1007/s11120-025-01184-z","url":null,"abstract":"<p><p>We model the energy transfers between two B850 antenna units using the hybrid hierarchical equation (HEOM) method, where intra-B850 dynamics is evaluated nonperturbatively using HEOM, whereas inter-B850 transfers are treated by the generalized Förster theory. To account for a conformation-induced energetic disorder we use a realistic model emerging from a quantitative explanation of the single molecule spectral fluctuations in the B850 antenna. The disorder produces a variety of configurations including realizations where the exciton states are predominantly localized at the red-shifted sites. A slow detrapping of excitation from the red states can compete with the transfers to the adjacent B850 unit, thus slowing down the whole equilibration dynamics. In order to highlight the interplay between intra-B850 dynamics and migration to neighboring B850 complex we analyze the diversity of scenarios produced by specific disorder patterns within both donor and acceptor units.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"61"},"PeriodicalIF":3.8,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145541907","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":"Quinol C-methyltransferases from extant species of early cyanobacterial lineages shed light on the emergence of plastoquinone in oxygenic phototrophs.","authors":"Gabriella Dickinson, Lauren R Stutts, Scott Latimer, Nathan Smith, Zhaniya Batyrshina, Monika Kula-Maximenko, Ireneusz Ślesak, Anna K Block, Mark A Wilson, Gilles J Basset","doi":"10.1007/s11120-025-01180-3","DOIUrl":"10.1007/s11120-025-01180-3","url":null,"abstract":"<p><p>Cyanobacteria and plastids harbor two prenylated quinones that serve as vital photosynthetic cofactors. One is a naphthoquinone (phylloquinone or menaquinone depending on the species), the naphthalene ring of which is always methylated in ortho of the prenyl chain. The other one is a benzoquinone, called plastoquinone-9, the benzenoid ring of which is, in contrast, never methylated at this position. In oxygenic phototrophs, such an arrangement is thought to have driven the evolution and retention of unique quinol C-methyltransferases that act exclusively on naphthoquinol substrates. Here, we identified quinol C-methyltransferases in two extant taxa of early cyanobacterial lineages, Gloeobacter violaceus and Synechococcus sp. JA-2-3B'a, that did not discriminate between naphthoquinol and benzoquinol substrates when these enzymes were expressed in Escherichia coli. Quinone analysis showed, however, that G. violaceus extracts did not contain any detectable amounts of methyl-plastoquinone-9. Furthermore, functional complementation assays in the cyanobacterium Synechocystis sp. PCC 6803 revealed that G. violaceus and S. sp. JA-2-3B'a quinol C-methyltransferases displayed either strict or marked substrate preference for demethyl-phylloquinol. Taken together, these data suggest that G. violaceus and S. sp. JA-2-3B'a quinol C-methyltransferases are the remnants of a promiscuous enzyme present during the emergence of plastoquinone as a photosynthetic electron carrier.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"59"},"PeriodicalIF":3.8,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145506308","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":"Investigating the role of PGR5 and PGRL1 in photosynthetic acclimation to salt stress in Chlamydomonas reinhardtii.","authors":"Siva Naga Sai Damaraju, Ranay Mohan Yadav, Namrata Dubey, Pavithra Ramachandran, Jyoti Ranjan Rath, Jerome Xavier Gunasekaran, Shriya Sharma, Rajagopal Subramanyam","doi":"10.1007/s11120-025-01179-w","DOIUrl":"10.1007/s11120-025-01179-w","url":null,"abstract":"<p><p>In this study, we aimed to understand the role of cyclic electron transport (CET) in the acclimation process in response to high salinity stress by comparing wild-type Chlamydomonas reinhardtii with CET deficient mutants, Proton Gradient Regulation 5 (PGR5), and Proton Gradient Regulation Like 1 (PGRL1). Cells grown in photoautotrophic conditions under salt stress resulted in a primary reduction in growth and chlorophyll fluorescence, as well as OJIP transient kinetics under salt stress, indicative of diminished photochemical efficiency. Notably, all strains exhibited a decrease in the variable fluorescence, and the non-photochemical quenching was accompanied by an increase in non-regulated energy dissipation. Additionally, salt treatment resulted in a reduction in total chlorophyll content and a related increase in carotenoid levels like violaxanthin, zeaxanthin, and lutein, and these levels were more pronounced in the pgr5. These alterations are likely linked to enhanced reactive oxygen species (ROS) generation under salt stress. The mutants were more sensitive to ROS and showed more carotenoid content than the wild type, suggesting a compensatory photoprotective mechanism. The circular dichroism data showed that the salt stress caused changes in pigment-pigment and pigment-protein interactions, which were more significant in mutants. When cells are exposed to high salt, there is a dynamic change in the core proteins, but light-harvesting complexes and antenna proteins of photosystem (PS) I and PSII are not much affected. Further, changes in cell morphology and thylakoid membrane organization were also observed in high salt stress. These data indicate PSI remodeling, defined here as stress-induced dissociation/rearrangement of PSI-LHCI(-LHCII) super complexes, reductions in PsaA/B abundance consistent with PSI core destabilization, and loss of thylakoid macro-domain order, particularly pronounced in pgr5.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"58"},"PeriodicalIF":3.8,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145445524","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":"Photophysical model of primary charge separation in green algal photosystem I based on combined analysis of time-resolved absorption and fluorescence spectra.","authors":"Wojciech Giera, Krzysztof Gibasiewicz","doi":"10.1007/s11120-025-01176-z","DOIUrl":"10.1007/s11120-025-01176-z","url":null,"abstract":"<p><p>The mechanism of primary charge separation in photosynthetic reaction centers is still not fully understood. In the case of photosystem I (PSI), the study of this process is particularly difficult due to the integration of the reaction center (RC) with the core antenna and presence of so-called red chlorophylls in the antenna system. Their excitation dynamics overlap spectrally and temporarily with the primary charge separation in RC. Therefore, we performed time-resolved absorption measurements (femtosecond pump-probe technique) for the red chlorophyll-free PSI core from green algae Chlamydomonas reinhardtii, both under reducing (open RC) and oxidizing (closed RC) conditions. Kinetic modeling of the recorded absorption changes indicated the same trapping rate of excitations by open and closed RC. Detailed spectral analysis showed, in turn, that processes related to the primary charge separation can be described by temporal evolution of several main well-defined spectral bands (with different contributions in the case of open and closed RC). We explained and thoroughly discussed their origin in the context of the excitonic coupling between the RC chlorophylls. We also implemented the identical kinetic model to the time-resolved fluorescence data published previously for exactly the same PSI preparation (Giera et al. 2014; Biochim Biophys Acta – Bioenergetics 1837:1756–1768). This combined analysis allowed us to identify different emission properties of the primary state generated in the open and closed RC after excitation trapping. The nature of this state is discussed.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"57"},"PeriodicalIF":3.8,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12575488/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145409715","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":"Biochemical characterization of PSI-FCPI and FCP complexes from a haptophyte Pavlova (Pavlovophyceae).","authors":"Hibiki Q Ito, Kano N Toyoizumi, Takehiro Suzuki, Akihiko Kanamoto, Tomohisa Hasunuma, Naoshi Dohmae, Ryo Nagao","doi":"10.1007/s11120-025-01175-0","DOIUrl":"10.1007/s11120-025-01175-0","url":null,"abstract":"<p><p>Most oxygenic photosynthesis relies on photosystem cores coupled with light-harvesting complexes (LHCs) to capture and funnel solar energy. In haptophytes, LHCs are represented by fucoxanthin chlorophyll (Chl) a/c-binding proteins (FCPs), which assemble into a photosystem I (PSI) supercomplex known as PSI-FCPI. However, the structural and pigment diversity of PSI-FCPI in early-branching haptophytes remains largely unexplored. Here, we present the first biochemical and spectroscopic characterization of PSI-FCPI and FCP complexes isolated from Pavlova sp. OPMS30543X, a member of the basal haptophyte lineage Pavlovophyceae. PSI-FCPI and FCP fractions were separated by glycerol density gradient centrifugation, revealing distinct pigment and protein compositions. Notably, a Chl c2-like pigment, previously detected only in whole-cell extracts of Pavlova, was identified in both complexes. Its red-shifted absorption relative to canonical Chl c2 suggests a specialized pigment-binding environment within the protein scaffolds. Additionally, an unknown carotenoid absorbing at 418, 441, and 469 nm was detected exclusively in the PSI-FCPI supercomplex, though its identity could not be confirmed owing to a mismatch in retention time with known references. Fluorescence-emission spectra revealed excitation-dependent energy transfer heterogeneity among Chl a species, indicating functional differentiation within the antenna system. Altogether, these results suggest that Pavlovophyceae retains ancestral pigment-protein configurations, providing new insights into the early evolution of light-harvesting systems in haptophytes.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"56"},"PeriodicalIF":3.8,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145377909","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":"Photosynthetic response of the invasive weed Chromolaena odorata to glyphosate.","authors":"K K Naidoo, G Naidoo","doi":"10.1007/s11120-025-01177-y","DOIUrl":"10.1007/s11120-025-01177-y","url":null,"abstract":"<p><p>This study investigated the herbicidal effects of glyphosate on the invasive perennial weed Chromolaena odorata. Natural weed populations of selected 1.2 m in height plants were sprayed with 1% glyphosate. Measurements of gas exchange, chlorophyll fluorescence and glyphosate concentrations were taken five consecutive days after spraying in late summer (February 2023). Glyphosate was determined by high-performance liquid chromatography (HPLC). After herbicide application, CO2 uptake decreased from 9.5 µmol m− 2s− 1 on day 1 to 0.95 µmol m− 2s− 1 on day 5. Leaf conductance and transpiration followed trends similar to those of CO2 uptake. Saturation of CO2 uptake occurred at a Photosynthetic Photon Flux Density (PPFD) of 1750 µmol m− 2s− 1 and at a leaf conductance of 0.09 mol m− 2s− 1 on day one. Trends in photosynthetic quantum yield (ΦPSII), electron transport rate (ETR) through Photosystem II (PSII) and maximum quantum yield (Fv/Fm) were similar to those of CO2 uptake. There was a linear relationship between CO2 uptake and leaf conductance, CO2 uptake and transpiration and CO2 uptake and Fv/Fm over all days. Initially, glyphosate concentrations were high in leaves and stems but declined with time. After day three, most glyphosate was located in roots, indicating transport from above to below-ground organs. Significant decreases in CO2 uptake, ΦPSII, and ETR through PSII and Fv/Fm indicate the inhibition of the shikimate pathway by glyphosate. The responses suggests that glyphosate was easily absorbed and translocated throughout the plant, resulting in wilting, abscission and 100% mortality within six days. This work provides novel information on the ecophysiological mechanism of glyphosate action in controlling C. odorata.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"55"},"PeriodicalIF":3.8,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145355712","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":"Revisiting the Q_A model of chlorophyll-a fluorescence induction: new perspectives to monitor the photochemical activity and structural dynamics of photosystem II.","authors":"Győző Garab","doi":"10.1007/s11120-025-01178-x","DOIUrl":"10.1007/s11120-025-01178-x","url":null,"abstract":"<p><p>The technique of chlorophyll-a fluorescence induction (ChlF) is widely used in plant biology. The 'mainstream', so-called Q_A model of ChlF, posits that the reaction centers (RCs) of Photosystem-II (PSII) exist in two states, quenched (F_o) or open (PSII_O), and unquenched (F_m) or closed (PSII_C), containing the primary quinone acceptor, Q_A, in oxidized and reduced state, respectively; and that the quantum yield of PSII photochemistry of a dark-adapted sample is Y(II) = F_v/F_m, where F_v=F_m-F_o. The widespread application of ChlF, with user-friendly instruments, and the use of the Q_A model, have substantially contributed to our understanding of the operation of the photosynthetic machineries under different environmental conditions. However, recent experimental data - multiple light-induced fluorescence increments in PSII_C; the complex, pH and temperature dependent kinetic and spectral features of key ChlF parameters; twith enhanced stabilization of the charges - cannot be reconciled with the Q_A model. These features are explained by subtle conformational transitions driven by stationary and transient electric fields and associated dielectric relaxation processes. This interpretation, while invites further studies, places the hitherto unknown structural and functional plasticity of the RC matrix in the context of its physiological significance.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 6","pages":"54"},"PeriodicalIF":3.8,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12549761/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145346376","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}