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Photosynthesis Research

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https://www.readbyqxmd.com/read/28432538/superoxide-generated-in-the-chloroplast-stroma-causes-photoinhibition-of-photosystem-i-in-the-shade-establishing-tree-species-psychotria-henryi
#1
Wei Huang, Ying-Jie Yang, Jiao-Lin Zhang, Hong Hu, Shi-Bao Zhang
Our previous studies indicated that high light induced significant photoinhibition of photosystem I (PSI) in the shade-establishing tree species Psychotria henryi. However, the underlying mechanism has not been fully clarified. In the present study, in order to investigate the mechanism of PSI photoinhibition in P. henryi, we treated detached leaves with constant high light in the presence of methyl viologen (MV) or a soluble α-tocopherol analog, 2,2,5,7,8-pentamethyl-6-chromanol (PMC). We found that MV significantly depressed photochemical quantum yields in PSI and PSII when compared to PMC...
April 21, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28425026/photosynthetic-responses-to-temperature-across-leaf-canopy-ecosystem-scales-a-15-year-study-in-a-californian-oak-grass-savanna
#2
Siyan Ma, Jessica L Osuna, Joseph Verfaillie, Dennis D Baldocchi
Ecosystem CO2 fluxes measured with eddy-covariance techniques provide a new opportunity to retest functional responses of photosynthesis to abiotic factors at the ecosystem level, but examining the effects of one factor (e.g., temperature) on photosynthesis remains a challenge as other factors may confound under circumstances of natural experiments. In this study, we developed a data mining framework to analyze a set of ecosystem CO2 fluxes measured from three eddy-covariance towers, plus a suite of abiotic variables (e...
April 19, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28425025/light-induced-formation-of-dimeric-lhcii
#3
Ewa Janik, Joanna Bednarska, Karol Sowinski, Rafal Luchowski, Monika Zubik, Wojciech Grudzinski, Wieslaw I Gruszecki
It emerges from numerous experiments that LHCII, the major photosynthetic antenna complex of plants, can appear not only in the trimeric or monomeric states but also as a dimer. We address the problem whether the dimeric form of the complex is just a simple intermediate element of the trimer-monomer transformation or if it can also be a physiologically relevant molecular organization form? Dimers of LHCII were analyzed with application of native electrophoresis, time-resolved fluorescence spectroscopy, and fluorescence correlation spectroscopy...
April 19, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28405863/high-light-acclimation-of-chromera-velia-points-to-photoprotective-npq
#4
Erica Belgio, Eliška Trsková, Eva Kotabová, Daniela Ewe, Ondřej Prášil, Radek Kaňa
It has previously been shown that the long-term treatment of Arabidopsis thaliana with the chloroplast inhibitor lincomycin leads to photosynthetic membranes enriched in antennas, strongly reduced in photosystem II reaction centers (PSII) and with enhanced nonphotochemical quenching (NPQ) (Belgio et al. Biophys J 102:2761-2771, 2012). Here, a similar physiological response was found in the microalga Chromera velia grown under high light (HL). In comparison to cells acclimated to low light, HL cells displayed a severe re-organization of the photosynthetic membrane characterized by (1) a reduction of PSII but similar antenna content; (2) partial uncoupling of antennas from PSII; (3) enhanced NPQ...
April 12, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28405862/isolation-and-characterization-of-psi-lhci-super-complex-and-their-sub-complexes-from-a-red-alga-cyanidioschyzon-merolae
#5
Lirong Tian, Zheyi Liu, Fangjun Wang, Liangliang Shen, Jinghua Chen, Lijing Chang, Songhao Zhao, Guangye Han, Wenda Wang, Tingyun Kuang, Xiaochun Qin, Jian-Ren Shen
Photosystem I (PSI)-light-harvesting complex I (LHCI) super-complex and its sub-complexes PSI core and LHCI, were purified from a unicellular red alga Cyanidioschyzon merolae and characterized. PSI-LHCI of C. merolae existed as a monomer with a molecular mass of 580 kDa. Mass spectrometry analysis identified 11 subunits (PsaA, B, C, D, E, F, I, J, K, L, O) in the core complex and three LHCI subunits, CMQ142C, CMN234C, and CMN235C in LHCI, indicating that at least three Lhcr subunits associate with the red algal PSI core...
April 12, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28405861/pk-a-of-ubiquinone-menaquinone-phylloquinone-plastoquinone-and-rhodoquinone-in-aqueous-solution
#6
Ryo Hasegawa, Keisuke Saito, Tomohiro Takaoka, Hiroshi Ishikita
Quinones can accept two electrons and two protons, and are involved in electron transfer and proton transfer reactions in photosynthetic reaction centers. To date, the pK a of these quinones in aqueous solution have not been reported. We calculated the pK a of the initial protonation (Q(·-) to QH(·)) and the second protonation (QH(-) to QH2) of 1,4-quinones using a quantum chemical approach. The calculated energy differences of the protonation reactions Q(·-) to QH(·) and QH(-) to QH2 in the aqueous phase for nine 1,4-quinones were highly correlated with the experimentally measured pK a(Q(·-)/QH(·)) and pK a(QH(-)/QH2), respectively...
April 12, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28405860/andr%C3%A3-tridon-jagendorf-1926-2017-a-personal-tribute
#7
Govindjee
We present here our tribute to an outstanding unique scientist, a pioneer of plant biochemistry, best known for his seminal ground-breaking discoveries related to electron and proton transport, and their intimate relation to ATP synthesis in chloroplasts. His dedication and in-depth understanding of science was matched by his humor. Here, we offer a modest précis of his life and research. We have also included Reminiscences from: Leonard Fish, Eric Larson, Donald Ort, Thomas Owens, and Robert Turgeon.
April 12, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28396976/preface-photosynthesis-and-hydrogen-energy-research-for-sustainability
#8
EDITORIAL
Tatsuya Tomo, Suleyman I Allakhverdiev
Energy supply, climate change, and global food security are among the main chalenges facing humanity in the twenty-first century. Despite global energy demand is continuing to increase, the availability of low cost energy is decreasing. Together with the urgent problem of climate change due to CO2 release from the combustion of fossil fuels, there is a strong requirement of developing the clean and renewable energy system for the hydrogen production. Solar fuel, biofuel, and hydrogen energy production gained unlimited possibility and feasibility due to understanding of the detailed photosynthetic system structures...
April 10, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28391379/heat-stress-induced-effects-of-photosystem-i-an-overview-of-structural-and-functional-responses
#9
REVIEW
Alexander G Ivanov, Maya Y Velitchkova, Suleyman I Allakhverdiev, Norman P A Huner
Temperature is one of the main factors controlling the formation, development, and functional performance of the photosynthetic apparatus in all photoautotrophs (green plants, algae, and cyanobacteria) on Earth. The projected climate change scenarios predict increases in air temperature across Earth's biomes ranging from moderate (3-4 °C) to extreme (6-8 °C) by the year 2100 (IPCC in Climate change 2007: The physical science basis: summery for policymakers, IPCC WG1 Fourth Assessment Report 2007; Climate change 2014: Mitigation of Climate Change, IPCC WG3 Fifth Assessment Report 2014)...
April 8, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28389747/light-dose-versus-rate-of-delivery-implications-for-macroalgal-productivity
#10
Matthew J Desmond, Daniel W Pritchard, Christopher D Hepburn
The role of how light is delivered over time is an area of macroalgal photosynthesis that has been overlooked but may play a significant role in controlling rates of productivity and the structure and persistence of communities. Here we present data that quantify the relative influence of total quantum dose and delivery rate on the photosynthetic productivity of five ecologically important Phaeophyceae species from southern New Zealand. Results suggested that greater net oxygen production occurs when light is delivered at a lower photon flux density (PFD) over a longer period compared to a greater PFD over a shorter period, given the same total dose...
April 7, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28386792/biophysical-modeling-of-in-vitro-and-in-vivo-processes-underlying-regulated-photoprotective-mechanism-in-cyanobacteria
#11
Evgeny A Shirshin, Elena E Nikonova, Fedor I Kuzminov, Nikolai N Sluchanko, Irina V Elanskaya, Maxim Y Gorbunov, Victor V Fadeev, Thomas Friedrich, Eugene G Maksimov
Non-photochemical quenching (NPQ) is a mechanism responsible for high light tolerance in photosynthetic organisms. In cyanobacteria, NPQ is realized by the interplay between light-harvesting complexes, phycobilisomes (PBs), a light sensor and effector of NPQ, the photoactive orange carotenoid protein (OCP), and the fluorescence recovery protein (FRP). Here, we introduced a biophysical model, which takes into account the whole spectrum of interactions between PBs, OCP, and FRP and describes the experimental PBs fluorescence kinetics, unraveling interaction rate constants between the components involved and their relative concentrations in the cell...
April 6, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28382592/the-absence-of-chlorophyll-b-affects-lateral-mobility-of-photosynthetic-complexes-and-lipids-in-grana-membranes-of-arabidopsis-and-barley-chlorina-mutants
#12
Elena V Tyutereva, Anastasiia I Evkaikina, Alexandra N Ivanova, Olga V Voitsekhovskaja
The lateral mobility of integral components of thylakoid membranes, such as plastoquinone, xanthophylls, and pigment-protein complexes, is critical for the maintenance of efficient light harvesting, high rates of linear electron transport, and successful repair of damaged photosystem II (PSII). The packaging of the photosynthetic pigment-protein complexes in the membrane depends on their size and stereometric parameters which in turn depend on the composition of the complexes. Chlorophyll b (Chlb) is an important regulator of antenna size and composition...
April 5, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28378245/the-identification-of-isia-proteins-binding-chlorophyll-d-in-the-cyanobacterium-acaryochloris-marina
#13
Zheng-Ke Li, Yan-Chao Yin, Lu-Dan Zhang, Zhong-Chun Zhang, Guo-Zheng Dai, Min Chen, Bao-Sheng Qiu
The bioavailable iron in many aquatic ecosystems is extremely low, and limits the growth and photosynthetic activity of phytoplankton. In response to iron limitation, a group of chlorophyll-binding proteins known as iron stress-induced proteins are induced and serve as accessory light-harvesting components for photosystems under iron limitation. In the present study, we investigated physiological features of Acaryochloris marina in response to iron-deficient conditions. The growth doubling time under iron-deficient conditions was prolonged to ~3...
April 4, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28374305/a-simple-and-efficient-method-to-prepare-pure-dimers-and-monomers-of-the-cytochrome-b-6-f-complex-from-spinach
#14
María A Luján, Patricia Lorente, Valter Zazubovich, Rafael Picorel
Using a single size-exclusion chromatography we were able to isolate highly pure dimers and monomers of the Cyt b 6 f complex from spinach from a bulk preparation of that protein complex obtained with a standard procedure. At higher protein/detergent ratio during the chromatography most of the Cyt b 6 f complex remained as dimers. In contrast, at lower protein/detergent ratio (around 15 times lower), most dimers became monomerized. As a bonus, this chromatography also allowed the elimination of potential Chl a contaminant to the Cyt b 6 f preparations...
April 3, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28365856/coupled-rows-of-pbs-cores-and-psii-dimers-in-cyanobacteria-symmetry-and-structure
#15
Dmitry V Zlenko, Tatiana V Galochkina, Pavel M Krasilnikov, Igor N Stadnichuk
Phycobilisome (PBS) is a giant water-soluble photosynthetic antenna transferring the energy of absorbed light mainly to the photosystem II (PSII) in cyanobacteria. Under the low light conditions, PBSs and PSII dimers form coupled rows where each PBS is attached to the cytoplasmic surface of PSII dimer, and PBSs come into contact with their face surfaces (state 1). The model structure of the PBS core that we have developed earlier by comparison and combination of different fine allophycocyanin crystals, as reported in Zlenko et al...
April 1, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28361449/interaction-and-electron-transfer-between-ferredoxin-nadp-oxidoreductase-and-its-partners-structural-functional-and-physiological-implications
#16
REVIEW
Paula Mulo, Milagros Medina
Ferredoxin-NADP(+) reductase (FNR) catalyzes the last step of linear electron transfer in photosynthetic light reactions. The FAD cofactor of FNR accepts two electrons from two independent reduced ferredoxin molecules (Fd) in two sequential steps, first producing neutral semiquinone and then the fully anionic reduced, or hydroquinone, form of the enzyme (FNRhq). FNRhq transfers then both electrons in a single hydride transfer step to NADP(+). We are presenting the recent progress in studies focusing on Fd:FNR interaction and subsequent electron transfer processes as well as on interaction of FNR with NADP(+)/H followed by hydride transfer, both from the structural and functional point of views...
March 30, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28361448/variability-of-aggregation-extent-of-light-harvesting-pigments-in-peripheral-antenna-of-chloroflexus-aurantiacus
#17
Andrei Yakovlev, Alexandra Taisova, Alexander Arutyunyan, Vladimir Shuvalov, Zoya Fetisova
The stationary ground state and femtosecond time-resolved absorption spectra as well as spectra of circular dichroism were measured at room temperature using freshly prepared samples of chlorosomes isolated from fresh cultures of the green bacterium Chloroflexus aurantiacus. Cultures were grown by using as inoculum the same seed culture but under different light conditions. All measured spectra clearly showed the red shift of BChl c Qy bands (up to 5 nm) for low-light chlorosomes as compared to high-light ones, together with concomitant narrowing of these bands and increasing of their amplitudes...
March 30, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28357617/interaction-of-various-types-of-photosystem-i-complexes-with-exogenous-electron-acceptors
#18
Anastasia A Petrova, Baina K Boskhomdzhieva, Georgy E Milanovsky, Olga A Koksharova, Mahir D Mamedov, Dmitry A Cherepanov, Alexey Yu Semenov
Interaction of photosystem I (PS I) complexes from cyanobacteria Synechocystis sp. PCC 6803 containing various quinones in the A1-site (phylloquinone PhQ in the wild-type strain (WT), and plastoquinone PQ or 2,3-dichloronaphthoquinone Cl 2 NQ in the menB deletion strain) and different numbers of Fe4S4 clusters (intact WT and FX-core complexes depleted of FA/FB centers) with external acceptors has been studied. The efficiency of interaction was estimated by measuring the light-induced absorption changes at 820 nm due to the reduction of the special pair of chlorophylls (P700(+)) by an external acceptor(s)...
March 29, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28382593/uncertainty-in-measurements-of-the-photorespiratory-co2-compensation-point-and-its-impact-on-models-of-leaf-photosynthesis
#19
Berkley J Walker, Douglas J Orr, Elizabete Carmo-Silva, Martin A J Parry, Carl J Bernacchi, Donald R Ort
Rates of carbon dioxide assimilation through photosynthesis are readily modeled using the Farquhar, von Caemmerer, and Berry (FvCB) model based on the biochemistry of the initial Rubisco-catalyzed reaction of net C3 photosynthesis. As models of CO2 assimilation rate are used more broadly for simulating photosynthesis among species and across scales, it is increasingly important that their temperature dependencies are accurately parameterized. A vital component of the FvCB model, the photorespiratory CO2 compensation point (Γ *), combines the biochemistry of Rubisco with the stoichiometry of photorespiratory release of CO2...
March 28, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28352992/kinetic-modeling-of-electron-transfer-reactions-in-photosystem-i-complexes-of-various-structures-with-substituted-quinone-acceptors
#20
Georgy E Milanovsky, Anastasia A Petrova, Dmitry A Cherepanov, Alexey Yu Semenov
The reduction kinetics of the photo-oxidized primary electron donor P700 in photosystem I (PS I) complexes from cyanobacteria Synechocystis sp. PCC 6803 were analyzed within the kinetic model, which considers electron transfer (ET) reactions between P700, secondary quinone acceptor A1, iron-sulfur clusters and external electron donor and acceptors - methylviologen (MV), 2,3-dichloro-naphthoquinone (Cl2NQ) and oxygen. PS I complexes containing various quinones in the A1-binding site (phylloquinone PhQ, plastoquinone-9 PQ and Cl2NQ) as well as F X-core complexes, depleted of terminal iron-sulfur F A/F B clusters, were studied...
March 28, 2017: Photosynthesis Research
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