TY - JOUR AU - Edrich, Elizabeth S. M. AU - Duvenage, Lucian AU - Gourlay, Campbell W. TI - Alternative Oxidase - Aid or obstacle to combat the rise of fungal pathogens? JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1865 PY - 2024 IS - 2 PG - 10 SN - 0005-2728 DO - 10.1016/j.bbabio.2024.149031 UR - https://m2.mtmt.hu/api/publication/34627572 ID - 34627572 LA - English DB - MTMT ER - TY - JOUR AU - Gelzinis, Andrius AU - Chmeliov, Jevgenij AU - Tutkus, Marijonas AU - Vitulskiene, Ernesta AU - Franckevicius, Marius AU - Buechel, Claudia AU - Robert, Bruno AU - Valkunas, Leonas TI - Fluorescence quenching in aggregates of fucoxanthin-chlorophyll protein complexes: Interplay of fluorescing and dark states JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1865 PY - 2024 IS - 2 PG - 10 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.149030 UR - https://m2.mtmt.hu/api/publication/34597926 ID - 34597926 AB - Diatoms, a major group of algae, account for about a quarter of the global primary production on Earth. These photosynthetic organisms face significant challenges due to light intensity variations in their underwater habitat. To avoid photodamage, they have developed very efficient non -photochemical quenching (NPQ) mechanisms. These mechanisms originate in their light -harvesting antenna - the fucoxanthin-chlorophyll protein (FCP) complexes. Spectroscopic studies of NPQ in vivo are often hindered by strongly overlapping signals from the photosystems and their antennae. Fortunately, in vitro FCP aggregates constitute a useful model system to study fluorescence (FL) quenching in diatoms. In this work, we present streak -camera FL measurements on FCPa and FCPb complexes, isolated from a centric diatom Cyclotella meneghiniana, and their aggregates. We find that spectra of non -aggregated FCP are dominated by a single fluorescing species, but the FL spectra of FCP aggregates additionally contain contributions from a redshifted emissive state. We relate this red state to a charge transfer state between chlorophyll c and chlorophyll a molecules. The FL quenching, on the other hand, is due to an additional dark state that involves incoherent energy transfer to the fucoxanthin carotenoids. Overall, the global picture of energy transfer and quenching in FCP aggregates is very similar to that of major light -harvesting complexes in higher plants (LHCII), but microscopic details between FCPs and LHCIIs differ significantly. LA - English DB - MTMT ER - TY - JOUR AU - Russell, Brandon P. AU - Vinyard, David J. TI - Conformational changes in a Photosystem II hydrogen bond network stabilize the oxygen-evolving complex JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1865 PY - 2024 IS - 1 PG - 6 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.149020 UR - https://m2.mtmt.hu/api/publication/34597130 ID - 34597130 AB - The Mn4CaO5 oxygen-evolving complex (OEC) in Photosystem II (PSII) is assembled in situ and catalyzes water oxidation. After OEC assembly, the PsbO extrinsic subunit docks to the lumenal face of PSII and both stabilizes the OEC and facilitates efficient proton transfer to the lumen. D1 residue R334 is part of a hydrogen bond network involved in proton release during catalysis and interacts directly with PsbO. D1-R334 has recently been observed in different conformations in apo-and holo-OEC PSII structures. We generated a D1-R334G point mutant in Synechocystis sp. PCC 6803 to better understand this residue's function. D1-R334G PSII is active under continuous light, but the OEC is unstable in darkness. Isolated D1-R334G core complexes have little bound PsbO and less manganese as the wild type control. The S2 intermediate is stabilized in D1-R334G indicating that the local environment around the OEC has been altered. These results suggest that the hydrogen bond network that includes D1-R334 exists in a different functional conformation during PSII biogenesis in the absence of PsbO. LA - English DB - MTMT ER - TY - JOUR AU - Gray, C. AU - Kailas, L. AU - Adams, P.G. AU - Duffy, C.D.P. TI - Unravelling the fluorescence kinetics of light-harvesting proteins with simulated measurements JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1865 PY - 2024 IS - 1 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.149004 UR - https://m2.mtmt.hu/api/publication/34405936 ID - 34405936 N1 - School of Biological and Chemical Sciences, Queen Mary University of London, Mile End, London, E1 4NS, United Kingdom School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom Export Date: 29 November 2023 CODEN: BBBEB Correspondence Address: Duffy, C.D.P.; School of Biological and Chemical Sciences, Mile End, United Kingdom; email: c.duffy@qmul.ac.uk AB - The plant light-harvesting pigment-protein complex LHCII is the major antenna sub-unit of PSII and is generally (though not universally) accepted to play a role in photoprotective energy dissipation under high light conditions, a process known Non-Photochemical Quenching (NPQ). The underlying mechanisms of energy trapping and dissipation within LHCII are still debated. Various models have been proposed for the underlying molecular detail of NPQ, but they are often based on different interpretations of very similar transient absorption measurements of isolated complexes. Here we present a simulated measurement of the fluorescence decay kinetics of quenched LHCII aggregates to determine whether this relatively simple measurement can discriminate between different potential NPQ mechanisms. We simulate not just the underlying physics (excitation, energy migration, quenching and singlet-singlet annihilation) but also the signal detection and typical experimental data analysis. Comparing this to a selection of published fluorescence decay kinetics we find that: (1) Different proposed quenching mechanisms produce noticeably different fluorescence kinetics even at low (annihilation free) excitation density, though the degree of difference is dependent on pulse width. (2) Measured decay kinetics are consistent with most LHCII trimers becoming relatively slow excitation quenchers. A small sub-population of very fast quenchers produces kinetics which do not resemble any observed measurement. (3) It is necessary to consider at least two distinct quenching mechanisms in order to accurately reproduce experimental kinetics, supporting the idea that NPQ is not a simple binary switch. © 2023 The Authors LA - English DB - MTMT ER - TY - JOUR AU - Zlenko, Dmitry V AU - Protasova, Elena A. AU - Tsoraev, Georgy V AU - Sluchanko, Nikolai N. AU - Cherepanov, Dmitry A. AU - Friedrich, Thomas AU - Ge, Baosheng AU - Qin, Song AU - Maksimov, Eugene G. AU - Rubin, Andrew B. TI - Anti-stokes fluorescence of phycobilisome and its complex with the orange carotenoid protein JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1865 PY - 2024 IS - 1 PG - 9 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.149014 UR - https://m2.mtmt.hu/api/publication/34261436 ID - 34261436 AB - Phycobilisomes (PBSs) are giant water-soluble light-harvesting complexes of cyanobacteria and red algae, consisting of hundreds of phycobiliproteins precisely organized to deliver the energy of absorbed light to chlorophyll chromophores of the photosynthetic electron-transport chain. Quenching the excess of excitation energy is necessary for the photoprotection of photosynthetic apparatus. In cyanobacteria, quenching of PBS excitation is provided by the Orange Carotenoid Protein (OCP), which is activated under high light conditions. In this work, we describe parameters of anti-Stokes fluorescence of cyanobacterial PBSs in quenched and unquenched states. We compare the fluorescence readout from entire phycobilisomes and their fragments. The obtained results revealed the heterogeneity of conformations of chromophores in isolated phycobiliproteins, while such heterogeneity was not observed in the entire PBS. Under excitation by low-energy quanta, we did not detect a significant uphill energy transfer from the core to the peripheral rods of PBS, while the one from the terminal emitters to the bulk allophycocyanin chromophores is highly probable. We show that this direction of energy migration does not eliminate fluorescence quenching in the complex with OCP. Thus, long-wave excitation provides new insights into the pathways of energy conversion in the phycobilisome. LA - English DB - MTMT ER - TY - JOUR AU - Gerle, C. AU - Misumi, Y. AU - Kawamoto, A. AU - Tanaka, H. AU - Kubota-Kawai, H. AU - Tokutsu, R. AU - Kim, E. AU - Chorev, D. AU - Abe, K. AU - Robinson, C.V. AU - Mitsuoka, K. AU - Minagawa, J. AU - Kurisu, G. TI - Three structures of PSI-LHCI from Chlamydomonas reinhardtii suggest a resting state re-activated by ferredoxin JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1864 PY - 2023 IS - 4 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.148986 UR - https://m2.mtmt.hu/api/publication/34565992 ID - 34565992 N1 - Life Science Research Infrastructure Group, RIKEN SPring-8 Center, Hyogo, Kouto, Japan Laboratory for Protein Crystallography, Institute for Protein Research, Osaka University, Osaka, Suita, Japan Faculty of Science, Department of Science, Yamagata University, Yamagata, Japan National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Japan Chemistry Research Laboratory, Oxford University, South Parks Road, United Kingdom Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka, Japan Department of Basic Biology, School of Life Science, the Graduate University for Advanced Studies, Okazaki, Sokendai, Japan Export Date: 8 February 2024 CODEN: BBBEB Correspondence Address: Gerle, C.; Life Science Research Infrastructure Group, Hyogo, Japan; email: christoph.gerle@riken.jp Correspondence Address: Kurisu, G.; Laboratory for Protein Crystallography, Osaka, Japan; email: gkurisu@protein.osaka-u.ac.jp AB - Photosystem I (PSI) from the green alga Chlamydomonas reinhardtii, with various numbers of membrane bound antenna complexes (LHCI), has been described in great detail. In contrast, structural characterization of soluble binding partners is less advanced. Here, we used X-ray crystallography and single particle cryo-EM to investigate three structures of the PSI-LHCI supercomplex from Chlamydomonas reinhardtii. An X-ray structure demonstrates the absence of six chlorophylls from the luminal side of the LHCI belts, suggesting these pigments were either physically absent or less stably associated with the complex, potentially influencing excitation transfer significantly. CryoEM revealed extra densities on luminal and stromal sides of the supercomplex, situated in the vicinity of the electron transfer sites. These densities disappeared after the binding of oxidized ferredoxin to PSI-LHCI. Based on these structures, we propose the existence of a PSI-LHCI resting state with a reduced active chlorophyll content, electron donors docked in waiting positions and regulatory binding partners positioned at the electron acceptor site. The resting state PSI-LHCI supercomplex would be recruited to its active form by the availability of oxidized ferredoxin. © 2023 The Author(s) LA - English DB - MTMT ER - TY - JOUR AU - Espinoza-Araya, Christopher AU - Starbird, Ricardo AU - Prasad, E. Senthil AU - Renugopalakrishnan, Venkatesan AU - Mulchandani, Ashok AU - Bruce, Barry D. AU - Villarreal, Claudia C. TI - A bacteriorhodopsin-based biohybrid solar cell using carbon-based electrolyte and cathode components JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1864 PY - 2023 IS - 4 PG - 10 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.148985 UR - https://m2.mtmt.hu/api/publication/34261222 ID - 34261222 AB - There is currently a high demand for energy production worldwide, mainly producing renewable and sustainable energy. Bio-sensitized solar cells (BSCs) are an excellent option in this field due to their optical and photoelectrical properties developed in recent years. One of the biosensitizers that shows promise in simplicity, stability and quantum efficiency is bacteriorhodopsin (bR), a photoactive, retinal-containing membrane protein. In the present work, we have utilized a mutant of bR, D96N, in a photoanode-sensitized TiO2 solar cell, integrating low-cost, carbon-based components, including a cathode composed of PEDOT (poly(3,4-ethylenedioxythiophene) functionalized with multi-walled carbon nanotubes (CNT) and a hydroquinone/benzoquinone (HQ/BQ) redox electrolyte. The photoanode and cathode were characterized morphologically and chemically (SEM, TEM, and Raman). The electrochemical performance of the bR-BSCs was investigated using linear sweep voltammetry (LSV), open circuit potential decay (VOC), and impedance spectroscopic analysis (EIS). The champion device yielded a current density (JSC) of 1.0 mA/cm(2), VOC of 669 mV, a fill factor of similar to 24 %, and a power conversion efficiency (PCE) of 0.16 %. This bR device is one of the first bio-based solar cells utilizing carbon-based alternatives for the photoanode, cathode, and electrolyte. This may decrease the cost and significantly improve the device's sustainability. LA - English DB - MTMT ER - TY - JOUR AU - Satoh, I. AU - Gotou, K. AU - Nagatsuma, S. AU - Nagashima, K. V. P. AU - Kobayashi, M. AU - Yu, L. -j. AU - Madigan, M. T. AU - Kimura, Y. AU - Wang-Otomo, Z. -y. TI - Selective expression of light-harvesting complexes alters phospholipid composition in the intracytoplasmic membrane and core complex of purple phototrophic bacteria JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1864 PY - 2023 IS - 4 PG - 7 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.149001 UR - https://m2.mtmt.hu/api/publication/34261096 ID - 34261096 AB - Phospholipid-protein interactions play important roles in regulating the function and morphology of photosynthetic membranes in purple phototrophic bacteria. Here, we characterize the phospholipid composition of intracytoplasmic membrane (ICM) from Rhodobacter (Rba.) sphaeroides that has been genetically altered to selectively express light-harvesting (LH) complexes. In the mutant strain (DP2) that lacks a peripheral lightharvesting (LH2) complex, the phospholipid composition was significantly different from that of the wild-type strain; strain DP2 showed a marked decrease in phosphatidylglycerol (PG) and large increases in cardiolipin (CL) and phosphatidylcholine (PC) indicating preferential interactions between the complexes and specific phospholipids. Substitution of the core light-harvesting (LH1) complex of Rba. sphaeroides strain DP2 with that from the purple sulfur bacterium Thermochromatium tepidum further altered the phospholipid composition, with substantial increases in PG and PE and decreases in CL and PC, indicating that the phospholipids incorporated into the ICM depend on the nature of the LH1 complex expressed. Purified LH1-reaction center core complexes (LH1-RC) from the selectively expressing strains also contained different phospholipid compositions than did core complexes from their corresponding wild-type strains, suggesting different patterns of phospholipid association between the selectively expressed LH1-RC complexes and those purified from native strains. Effects of carotenoids on the phospholipid composition were also investigated using carotenoid-suppressed cells and carotenoid-deficient species. The findings are discussed in relation to ICM morphology and specific LH complex-phospholipid interactions. LA - English DB - MTMT ER - TY - JOUR AU - Pavlou, Andrea AU - Mokvist, Fredrik AU - Styring, Stenbjorn AU - Mamedov, Fikret TI - Far-red photosynthesis: Two charge separation pathways exist in plant Photosystem II reaction center JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1864 PY - 2023 IS - 4 PG - 11 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.148994 UR - https://m2.mtmt.hu/api/publication/34261069 ID - 34261069 AB - An alternative charge separation pathway in Photosystem II under the far-red light was proposed by us on the basis of electron transfer properties at 295 K and 5 K. Here we extend these studies to the temperature range of 77-295 K with help of electron paramagnetic resonance spectroscopy. Induction of the S2 state multiline signal, oxidation of Cytochrome b559 and ChlorophyllZ was studied in Photosystem II membrane preparations from spinach after application of a laser flashes in visible (532 nm) or far-red (730-750 nm) spectral regions. Temperature dependence of the S2 state signal induction after single flash at 730-750 nm (Tinhibition - 240 K) was found to be different than that at 532 nm (Tinhibition - 157 K). No contaminant oxidation of the secondary electron donors cytochrome b559 or chlorophyllZ was observed. Photoaccumulation experiments with extensive flashing at 77 K showed similar results, with no or very little induction of the secondary electron donors. Thus, the partition ratio defined as (yield of YZ/CaMn4O5-cluster oxidation):(yield of Cytb559/ChlZ/CarD2 oxidation) was found to be 0.4 at under visible light and 1.7 at under far-red light at 77 K. Our data indicate that different products of charge separation after far-red light exists in the wide temperature range which further support the model of the different primary photochemistry in Photosystem II with localization of hole on the ChlD1 molecule. LA - English DB - MTMT ER - TY - JOUR AU - Khorobrykh, Andrey TI - A possible relationship between the effect of factors on photoactivation of photosystem II depleted of functional Mn and cytochrome b559 JF - BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS J2 - BBA-BIOENERGETICS VL - 1864 PY - 2023 IS - 4 PG - 9 SN - 0005-2728 DO - 10.1016/j.bbabio.2023.148997 UR - https://m2.mtmt.hu/api/publication/34260698 ID - 34260698 AB - The photoassembly of the Mn4CaO5 cluster in Mn-depleted photosystem II preparations (photoactivation) was studied under the influence of oxidants, reductants and pH. New data on the effect of these factors on the photoactivation yield are presented. The presence of the oxidant, ferricyanide, negatively affected the photoactivation yield over the entire concentration range studied (0-1 mM). In contrast to ferricyanide, the addition of the reductant, ferrocyanide, up to 1 mM resulted in an increase in the photoactivation yield. Other reductants either did not significantly affect (diphenylcarbazide) or suppressed (ascorbate) the photoactivation yield. The effect of ferrocyanide on photoactivation were found to be similar dichlorophenolindophenol. Investigation of the photoactivation yield as a function of pH revealed that the maximum yield was observed at pH 6.5 in the presence of ferrocyanide and DCPIP, and at pH 5.5 without additives. In addition, the photoactivation yield at pH 5.5 was the same without and with the addition of ferrocyanide or dichlorophenolindophenol. Although ferricyanide suppressed the photoactivation, the photoactivation yield increased in the presence of ferricyanide by shifting the pH to the acidic region. The samples contained approximately 25 % of the HP cyt b559, which was in the reduced state, as the absorbance at 559 nm was decreased upon addition of ferricyanide and subsequent addition of ferrocyanide returned the spectrum to the baseline. A possible relationship between the effect of factors on the photoactivation and the involvement of cyt b559 in the protection of PSII from oxidative damage on the donor side is discussed. LA - English DB - MTMT ER -