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Photosynthesis Research

Daisuke Takagi, Kentaro Ifuku, Taishi Nishimura, Chikahiro Miyake
The light reactions of photosynthesis are known to comprise both linear and cyclic electron flow in order to convert light energy into chemical energy in the form of NADPH and ATP. Antimycin A (AA) has been proposed as an inhibitor of ferredoxin-dependent cyclic electron flow around photosystem I (CEF-PSI) in photosynthesis research. However, its precise inhibitory mechanism and target site had not been elucidated yet. Here we show that AA inhibits the cyclic (alternative) electron flow via cytochrome b559 (Cyt b559 ) within photosystem II (CEF-PSII)...
May 22, 2018: Photosynthesis Research
Aiguo Zhao, Feng Han
In higher plants, the tetrapyrrole biosynthesis pathway starts from the reaction catalyzed by the rate-limiting enzyme, glutamyl-tRNAGlu reductase (GTR). In Arabidopsis thaliana, GTR is controlled by post-transcriptional regulators such as GTR binding protein (GBP), which stimulates AtGTR activity. The NADPH-binding domain of AtGTR undergoes a substantial movement upon GBP binding. Here, we report the crystal structure of AtGTR-NADPH-GBP ternary complex. NADPH binding causes slight structural changes compared with the AtGTR-GBP binary complex, and possibly take a part of the space needed by the substrate glutamyl-tRNAGlu ...
May 21, 2018: Photosynthesis Research
Ilya E Zlobin, Yury V Ivanov, Alexander V Kartashov, Boris A Sarvin, Andrey N Stavrianidi, Vladimir D Kreslavski, Vladimir V Kuznetsov
We investigated the influence of 40 days of drought on growth, storage processes and primary photosynthetic processes in 3-month-old Scots pine and Norway spruce seedlings growing in perlite culture. Water stress significantly affected seedling water status, whereas absolute dry biomass growth was not substantially influenced. Water stress induced an increase in non-structural carbohydrate content (sugars, sugar alcohols, starch) in the aboveground part of pine seedlings in contrast to spruce seedlings. Due to the relatively low content of sugars and sugar alcohols in seedling organs, their expected contribution to osmotic potential changes was quite low...
May 19, 2018: Photosynthesis Research
Makoto Nakamura, Alain Boussac, Miwa Sugiura
Cytb559 in Photosystem II is a heterodimeric b-type cytochrome. The subunits, PsbE and PsbF, consist each in a membrane α-helix. Mutants were previously designed and studied in Thermosynechococcus elongatus (Sugiura et al., Biochim Biophys Acta 1847:276-285, 2015) either in which an axial histidine ligand of the haem-iron was substituted for a methionine, the PsbE/H23M mutant in which the haem was lacking, or in which the haem environment was modified, the PsbE/Y19F and PsbE/T26P mutants. All these mutants remained active showing that the haem has no structural role provided that PsbE and PsbF subunits are present...
May 19, 2018: Photosynthesis Research
Matthias Gilbert, Hanno Bährs, Christian E W Steinberg, Christian Wilhelm
Humic substances (HSs) can influence the growth and composition of freshwater phytoplankton assemblage. Since HSs contain many phenolic and quinonic moieties and cause growth reductions in eco-physiological field experiments, HSs are considered photosystem II herbicides. To test this specific mode of action in vivo and in vitro, respectively, we used intact cells of the green alga Desmodesmus armatus, as well as thylakoids isolated from spinach (Spinacia oleracea) as a model system for the green algal chloroplast...
May 18, 2018: Photosynthesis Research
Hermann Bothe, Thomas Happe, Simon Trebst, Matthias Rögner
The life and work of Achim Trebst (1929-2017) was dedicated to photosynthesis, involving a wide span of seminal contributions which cumulated in more than five decades of active research: Major topics include the separation of light and dark phases in photosynthesis, the elucidation of photosynthesis by the use of inhibitors, the identification of the three-dimensional structure of photosystem II and its degradation, and an explanation of singlet oxygen formation. For this tribute, which has been initiated by Govindjee, twenty-two personal tributes by former coworkers, scientific friends, and his family have been compiled and combined with an introduction tracing the different stages of Achim Trebst's scientific life...
May 16, 2018: Photosynthesis Research
Anastasia Petrova, Mahir Mamedov, Boris Ivanov, Alexey Semenov, Marina Kozuleva
The peculiarities of interaction of cyanobacterial photosystem I with redox mediators 2,6-dichlorophenolindophenol (DCPIP) and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) were investigated. The higher donor efficiency of the reduced DCPIP form was demonstrated. The oxidized form of DCPIP was shown to be an efficient electron acceptor for terminal iron-sulfur cluster of photosystem I. Likewise methyl viologen, after one-electron reduction, DCPIP transfers an electron to the molecular oxygen. These results were discussed in terms of influence of these interactions on photosystem I reactions with the molecular oxygen and natural electron acceptors...
May 16, 2018: Photosynthesis Research
Shinya Wada, Yuji Suzuki, Daisuke Takagi, Chikahiro Miyake, Amane Makino
Under CO2 -limited conditions such as during stomatal closure, photorespiration is suggested to act as a sink for excess light energy and protect photosystem I (PSI) by oxidizing its reaction center chlorophyll P700. In this study, this issue was directly examined with rice (Oryza sativa L.) plants via genetic manipulation of the amount of Rubisco, which can be a limiting factor for photorespiration. At low [CO2 ] of 5 Pa that mimicked stomatal closure condition, the activity of photorespiration in transgenic plants with decreased Rubisco content (RBCS-antisense plants) markedly decreased, whereas the activity in transgenic plants with overproduction of Rubisco (RBCS-sense plants) was similar to that in wild-type plants...
May 14, 2018: Photosynthesis Research
Antoaneta V Popova, Konstantin Dobrev, Maya Velitchkova, Alexander G Ivanov
The high-light-induced alterations in photosynthetic performance of photosystem II (PSII) and photosystem I (PSI) as well as effectiveness of dissipation of excessive absorbed light during illumination for different periods of time at room (22 °C) and low (8-10 °C) temperature of leaves of Arabidopsis thaliana, wt and lut2, were followed with the aim of unraveling the role of lutein in the process of photoinhibition. Photosynthetic parameters of PSII and PSI were determined on whole leaves by PAM fluorometer and oxygen evolving activity-by a Clark-type electrode...
May 3, 2018: Photosynthesis Research
Dariusz M Niedzwiedzki, Alastair T Gardiner, Robert E Blankenship, Richard J Cogdell
Three photosynthetic membranes, called intra-cytoplasmic membranes (ICMs), from wild-type and the ∆pucBAabce mutant of the purple phototrophic bacterium Rps. palustris were investigated using optical spectroscopy. The ICMs contain identical light-harvesting complex 1-reaction centers (LH1-RC) but have various spectral forms of light-harvesting complex 2 (LH2). Spectroscopic studies involving steady-state absorption, fluorescence, and femtosecond time-resolved absorption at room temperature and at 77 K focused on inter-protein excitation energy transfer...
May 3, 2018: Photosynthesis Research
Makio Yokono, Ikumi Umetani, Atushi Takabayashi, Seiji Akimoto, Ayumi Tanaka
Recently, we isolated a complex consisting of photosystem II (PSII) and light-harvesting complexes (LHCs) from Nannochloropsis granulata (Umetani et al. Photosynth Res 136:49-61, 2017). This complex contained stress-related protein, Lhcx, as a major component of LHC (Protein ID is Naga_100173g12.1), suggesting that non-photochemical quenching activities may be taking place in the PSII-LHC complex. In this study, we examined the energy transfer dynamics in the isolated LHCs and PSII-LHC complexes, and found substantial quenching capacity...
April 27, 2018: Photosynthesis Research
Jing-Hua Chen, Long-Jiang Yu, Alain Boussac, Zheng-Yu Wang-Otomo, Tingyun Kuang, Jian-Ren Shen
The thermophilic purple sulfur bacterium Thermochromatium tepidum possesses four main water-soluble redox proteins involved in the electron transfer behavior. Crystal structures have been reported for three of them: a high potential iron-sulfur protein, cytochrome c', and one of two low-potential cytochrome c 552 (which is a flavocytochrome c) have been determined. In this study, we purified another low-potential cytochrome c 552 (LPC), determined its N-terminal amino acid sequence and the whole gene sequence, characterized it with absorption and electron paramagnetic spectroscopy, and solved its high-resolution crystal structure...
April 24, 2018: Photosynthesis Research
Ravi R Sonani, Alastair Gardiner, Rajesh P Rastogi, Richard Cogdell, Bruno Robert, Datta Madamwar
In the original publication, under the subtitle Recovery: fluorescence recovery protein (FRP), paragraph 4 the text section enclosed in quotation marks does not occur in one of the original publications cited (Sluchanko et al. 2017a, b).
April 23, 2018: Photosynthesis Research
R Perkins, C Williamson, J Lavaud, J-L Mouget, D A Campbell
Photoacclimation by strains of Haslea "blue" diatom species H. ostrearia and H. silbo sp. nov. ined. was investigated with rapid light curves and induction-recovery curves using fast repetition rate fluorescence. Cultures were grown to exponential phase under 50 µmol m-2  s-1 photosynthetic available radiation (PAR) and then exposed to non-sequential rapid light curves where, once electron transport rate (ETR) had reached saturation, light intensity was decreased and then further increased prior to returning to near growth light intensity...
April 16, 2018: Photosynthesis Research
Wojciech Giera, Sebastian Szewczyk, Michael D McConnell, Kevin E Redding, Rienk van Grondelle, Krzysztof Gibasiewicz
Energetic properties of chlorophylls in photosynthetic complexes are strongly modulated by their interaction with the protein matrix and by inter-pigment coupling. This spectral tuning is especially striking in photosystem I (PSI) complexes that contain low-energy chlorophylls emitting above 700 nm. Such low-energy chlorophylls have been observed in cyanobacterial PSI, algal and plant PSI-LHCI complexes, and individual light-harvesting complex I (LHCI) proteins. However, there has been no direct evidence of their presence in algal PSI core complexes lacking LHCI...
April 4, 2018: Photosynthesis Research
Jeremias C Zill, Zhihui He, Marcus Tank, Bryan H Ferlez, Daniel P Canniffe, Yigal Lahav, Peter Bellstedt, A Alia, Igor Schapiro, John H Golbeck, Donald A Bryant, Jörg Matysik
Photochemically induced dynamic nuclear polarization (photo-CIDNP) has been observed in the homodimeric, type-1 photochemical reaction centers (RCs) of the acidobacterium, Chloracidobacterium (Cab.) thermophilum, by15 N magic-angle spinning (MAS) solid-state NMR under continuous white-light illumination. Three light-induced emissive (negative) signals are detected. In the RCs of Cab. thermophilum, three types of (bacterio)chlorophylls have previously been identified: bacteriochlorophyll a (BChl a), chlorophyll a (Chl a), and Zn-bacteriochlorophyll a' (Zn-BChl a') (Tsukatani et al...
March 30, 2018: Photosynthesis Research
Gregory S Orf, Christopher Gisriel, Kevin E Redding
The proliferation of phototrophy within early-branching prokaryotes represented a significant step forward in metabolic evolution. All available evidence supports the hypothesis that the photosynthetic reaction center (RC)-the pigment-protein complex in which electromagnetic energy (i.e., photons of visible or near-infrared light) is converted to chemical energy usable by an organism-arose once in Earth's history. This event took place over 3 billion years ago and the basic architecture of the RC has diversified into the distinct versions that now exist...
March 30, 2018: Photosynthesis Research
Alonso M Acuña, Pascal van Alphen, Filipe Branco Dos Santos, Rienk van Grondelle, Klaas J Hellingwerf, Ivo H M van Stokkum
Photosynthetic activity and respiration share the thylakoid membrane in cyanobacteria. We present a series of spectrally resolved fluorescence experiments where whole cells of the cyanobacterium Synechocystis sp. PCC 6803 and mutants thereof underwent a dark-to-light transition after different dark-adaptation (DA) periods. Two mutants were used: (i) a PSI-lacking mutant (ΔPSI) and (ii) M55, a mutant without NAD(P)H dehydrogenase type-1 (NDH-1). For comparison, measurements of the wild-type were also carried out...
March 29, 2018: Photosynthesis Research
Denitsa Nikolova, Claudia Heilmann, Susan Hawat, Philipp Gäbelein, Michael Hippler
The absolute amount of plastocyanin (PC), ferredoxin-NADP+ -oxidoreductase (FNR), hydrogenase (HYDA1), and ferredoxin 5 (FDX5) were quantified in aerobic and anaerobic Chlamydomonas reinhardtii whole cells using purified (recombinant) proteins as internal standards in a mass spectrometric approach. Quantified protein amounts were related to the estimated amount of PSI. The ratios of PC to FNR to HYDA1 to FDX5 in aerobic cells were determined to be 1.4:1.2:0.003:0. In anaerobic cells, the ratios changed to 1...
March 28, 2018: Photosynthesis Research
Mohammad Mahdi Najafpour, Navid Jameei Moghaddam, Leila Hassani, Robabeh Bagheri, Zhenlun Song, Suleyman I Allakhverdiev
Nature uses a Mn oxide-based catalyst for water oxidation in plants, algae, and cyanobacteria. Mn oxides are among major candidates to be used as water-oxidizing catalysts. Herein, we used two straightforward and promising methods to form Escherichia coli bacteria/Mn oxide compounds. In one of the methods, the bacteria template was intact after the reaction. The catalysts were characterized by X-ray photoelectron spectroscopy, visible spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, diffuse reflectance infrared Fourier transform spectroscopy, Raman spectroscopy, and X-ray diffraction spectrometry...
March 27, 2018: Photosynthesis Research
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