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Photosynthesis Research

Taishi Nishimura, Fumihiko Sato, Kentaro Ifuku
The PsbP protein is an extrinsic subunit of photosystem II (PSII) specifically developed in green-plant species including land plants and green algae. The protein-protein interactions involving PsbP and its effect on oxygen evolution have been investigated in vitro using isolated PSII membranes. However, the importance of those interactions needs to be examined at the cellular level. To this end, we developed a system expressing exogenous PsbP in the background of the Chlamydomonas BF25 mutant lacking native PsbP...
March 24, 2017: Photosynthesis Research
Nadezhda P Yurina, Vladimir O Popov, Alexander A Krasnovsky, Govindjee
Navasard Vaganovich Karapetyan (September 6, 1936-March 6, 2015) began his scientific career at the Bach Institute of Biochemistry of the Russian Academy of Sciences, Moscow, and was associated with this institute for over 56 years. He worked in the area of biochemistry and biophysics of photosynthesis and was especially known for his studies on chlorophyll a fluorescence in higher plants and cyanobacteria, molecular organization of Photosystem I, photoprotective energy dissipation, and dynamics of energy migration in the two photosystems...
March 17, 2017: Photosynthesis Research
Tibor Stolárik, Boris Hedtke, Jiří Šantrůček, Petr Ilík, Bernhard Grimm, Andrej Pavlovič
No abstract text is available yet for this article.
March 13, 2017: Photosynthesis Research
Silas Busck Mellor, Konstantinos Vavitsas, Agnieszka Zygadlo Nielsen, Poul Erik Jensen
Plants, cyanobacteria, and algae generate a surplus of redox power through photosynthesis, which makes them attractive for biotechnological exploitations. While central metabolism consumes most of the energy, pathways introduced through metabolic engineering can also tap into this source of reducing power. Recent work on the metabolic engineering of photosynthetic organisms has shown that the electron carriers such as ferredoxin and flavodoxin can be used to couple heterologous enzymes to photosynthetic reducing power...
March 11, 2017: Photosynthesis Research
Takako Ogawa, Masahiro Misumi, Kintake Sonoike
Cyanobacteria are photosynthetic prokaryotes and widely used for photosynthetic research as model organisms. Partly due to their prokaryotic nature, however, estimation of photosynthesis by chlorophyll fluorescence measurements is sometimes problematic in cyanobacteria. For example, plastoquinone pool is reduced in the dark-acclimated samples in many cyanobacterial species so that conventional protocol developed for land plants cannot be directly applied for cyanobacteria. Even for the estimation of the simplest chlorophyll fluorescence parameter, F v/F m, some additional protocol such as addition of DCMU or illumination of weak blue light is necessary...
March 10, 2017: Photosynthesis Research
Alexander N Tikhonov, Alexey V Vershubskii
In chloroplasts, photosynthetic electron transport complexes interact with each other via the mobile electron carriers (plastoquinone and plastocyanin) which are in surplus amounts with respect to photosystem I and photosystem II (PSI and PSII), and the cytochrome b 6 f complex. In this work, we analyze experimental data on the light-induced redox transients of photoreaction center P700 in chloroplasts within the framework of our mathematical model. This analysis suggests that during the action of a strong actinic light, even significant attenuation of PSII [for instance, in the result of inhibition of a part of PSII complexes by DCMU or due to non-photochemical quenching (NPQ)] will not cause drastic shortage of electron flow through PSI...
March 8, 2017: Photosynthesis Research
Haijun Liu, Yue Lu, Benjamin Wolf, Rafael Saer, Jeremy D King, Robert E Blankenship
Photosynthesis starts with absorption of light energy by light-harvesting antenna complexes with subsequent production of energy-rich organic compounds. However, all photosynthetic organisms face the challenge of excess photochemical conversion capacity. In cyanobacteria, non-photochemical quenching (NPQ) performed by the orange carotenoid protein (OCP) is one of the most important mechanisms to regulate the light energy captured by light-harvesting antennas. This regulation permits the cell to meet its cellular energy requirements and at the same time protects the photosynthetic apparatus under fluctuating light conditions...
March 7, 2017: Photosynthesis Research
Svea Wilkening, Franz-Josef Schmitt, Marius Horch, Ingo Zebger, Oliver Lenz, Thomas Friedrich
The fluorescent biosensor Frex, recently introduced as a sensitive tool to quantify the NADH concentration in living cells, was characterized by time-integrated and time-resolved fluorescence spectroscopy regarding its applicability for in vivo measurements. Based on the purified sensor protein, it is shown that the NADH dependence of Frex fluorescence can be described by a Hill function with a concentration of half-maximal sensor response of K D  ≈ 4 µM and a Hill coefficient of n ≈ 2. Increasing concentrations of NADH have moderate effects on the fluorescence lifetime of Frex, which changes by a factor of two from about 500 ps in the absence of NADH to 1 ns under fluorescence-saturating NADH concentrations...
March 6, 2017: Photosynthesis Research
Mariann Kis, Gábor Sipka, Péter Maróti
Mercury adsorption on the cell surface and intracellular uptake by bacteria represent the key first step in the production and accumulation of highly toxic mercury in living organisms. In this work, the biophysical characteristics of mercury bioaccumulation are studied in intact cells of photosynthetic bacteria by use of analytical (dithizone) assay and physiological photosynthetic markers (pigment content, fluorescence induction, and membrane potential) to determine the amount of mercury ions bound to the cell surface and taken up by the cell...
March 4, 2017: Photosynthesis Research
Maksym Golub, Mahdi Hejazi, Adrian Kölsch, Heiko Lokstein, D C Florian Wieland, Athina Zouni, Jörg Pieper
The structure of monomeric and trimeric photosystem I (PS I) of Thermosynechococcus elongatus BP1 (T. elongatus) was investigated by small-angle X-ray scattering (SAXS). The scattering data reveal that the protein-detergent complexes possess radii of gyration of 58 and 78 Å in the cases of monomeric and trimeric PS I, respectively. The results also show that the samples are monodisperse, virtually free of aggregation, and contain empty detergent micelles. The shape of the protein-detergent complexes can be well approximated by elliptical cylinders with a height of 78 Å...
March 3, 2017: Photosynthesis Research
Alexei Solovchenko, Konstantin Neverov
Carotenoids are a diverse group of terpenoid pigments ubiquitous in and essential for functioning of phototrophs. Most of the researchers in the field are focused on the primary carotenoids serving light harvesting, photoprotection, and supporting the structural integrity of the photosynthetic apparatus (PSA) within the thylakoid membranes. A distinct group of the pigments functionally and structurally uncoupled from the PSA and accumulating outside of the thylakoids is called secondary carotenoids. Induction of the biosynthesis and massive accumulation of the latter termed as secondary carotenogenesis and carotenogenic response (CR), respectively, is a major though insufficiently studied stress response discovered in many phototrophic organisms ranging from single-celled algae to terrestrial higher plants...
March 1, 2017: Photosynthesis Research
Jessica Schmitz, Nishtala V Srikanth, Meike Hüdig, Gereon Poschmann, Martin J Lercher, Veronica G Maurino
Like other oxygenic photosynthetic organisms, diatoms produce glycolate, a toxic intermediate, as a consequence of the oxygenase activity of Rubisco. Diatoms can remove glycolate through excretion and through oxidation as part of the photorespiratory pathway. The diatom Phaeodactylum tricornutum encodes two proteins suggested to be involved in glycolate metabolism: PtGO1 and PtGO2. We found that these proteins differ substantially from the sequences of experimentally characterized proteins responsible for glycolate oxidation in other species, glycolate oxidase (GOX) and glycolate dehydrogenase...
February 28, 2017: Photosynthesis Research
Graham R Fleming
Progress in measuring and understanding the mechanism of the elementary energy transfer steps in photosynthetic light harvesting from roughly 1949 to the present is sketched with a focus on the group of scientists born in 1949 ± 1. Improvements in structural knowledge, laser spectroscopic methods, and quantum dynamical theories have led to the ability to record and calculate with reasonable accuracy the timescales of elementary energy transfer steps. The significance of delocalized excited states and of near-field Coulombic coupling is noted...
February 28, 2017: Photosynthesis Research
Hazem M Kalaji, Gert Schansker, Marian Brestic, Filippo Bussotti, Angeles Calatayud, Lorenzo Ferroni, Vasilij Goltsev, Lucia Guidi, Anjana Jajoo, Pengmin Li, Pasquale Losciale, Vinod K Mishra, Amarendra N Misra, Sergio G Nebauer, Simonetta Pancaldi, Consuelo Penella, Martina Pollastrini, Kancherla Suresh, Eduardo Tambussi, Marcos Yanniccari, Marek Zivcak, Magdalena D Cetner, Izabela A Samborska, Alexandrina Stirbet, Katarina Olsovska, Kristyna Kunderlikova, Henry Shelonzek, Szymon Rusinowski, Wojciech Bąba
No abstract text is available yet for this article.
February 27, 2017: Photosynthesis Research
Vinzenz Bayro-Kaiser, Nathan Nelson
Modern energy production is required to undergo a dramatic transformation. It will have to replace fossil fuel use by a sustainable and clean energy economy while meeting the growing world energy needs. This review analyzes the current energy sector, available energy sources, and energy conversion technologies. Solar energy is the only energy source with the potential to fully replace fossil fuels, and hydrogen is a crucial energy carrier for ensuring energy availability across the globe. The importance of photosynthetic hydrogen production for a solar-powered hydrogen economy is highlighted and the development and potential of this technology are discussed...
February 26, 2017: Photosynthesis Research
Kalva Madhana Sekhar, Kanubothula Sitarami Reddy, Attipalli Ramachandra Reddy
Present study describes the responses of short rotation coppice (SRC) mulberry, a potential bio-energy tree, grown under interactive environment of elevated CO2 (E) and water stress (WS). Growth in E stimulated photosynthetic performance in well-watered (WW) as well as during WS with significant increases in light-saturated photosynthetic rates (A Sat), water use efficiency (WUEi), intercellular [CO2], and photosystem-II efficiency (F V/F M and ∆F/F M') with concomitant reduction in stomatal conductance (g s) and transpiration (E) compared to ambient CO2 (A) grown plants...
February 25, 2017: Photosynthesis Research
Marcus Moldenhauer, Nikolai N Sluchanko, Neslihan N Tavraz, Cornelia Junghans, David Buhrke, Mario Willoweit, Leonardo Chiappisi, Franz-Josef Schmitt, Vladana Vukojević, Evgeny A Shirshin, Vladimir Y Ponomarev, Vladimir Z Paschenko, Michael Gradzielski, Eugene G Maksimov, Thomas Friedrich
Photoprotection in cyanobacteria relies on the interplay between the orange carotenoid protein (OCP) and the fluorescence recovery protein (FRP) in a process termed non-photochemical quenching, NPQ. Illumination with blue-green light converts OCP from the basic orange state (OCP(O)) into the red-shifted, active state (OCP(R)) that quenches phycobilisome (PBs) fluorescence to avoid excessive energy flow to the photosynthetic reaction centers. Upon binding of FRP, OCP(R) is converted to OCP(O) and dissociates from PBs; however, the mode and site of OCP(R)/FRP interactions remain elusive...
February 24, 2017: Photosynthesis Research
Tibor Stolárik, Boris Hedtke, Jiří Šantrůček, Petr Ilík, Bernhard Grimm, Andrej Pavlovič
Unlike angiosperms, gymnosperms use two different enzymes for the reduction of protochlorophyllide to chlorophyllide: the light-dependent protochlorophyllide oxidoreductase (LPOR) and the dark-operative protochlorophyllide oxidoreductase (DPOR). In this study, we examined the specific role of both enzymes for chlorophyll synthesis in response to different light/dark and temperature conditions at different developmental stages (cotyledons and needles) of Norway spruce (Picea abies Karst.). The accumulation of chlorophyll and chlorophyll-binding proteins strongly decreased during dark growth in secondary needles at room temperature as well as in cotyledons at low temperature (7 °C) indicating suppression of DPOR activity...
February 22, 2017: Photosynthesis Research
Marcus Moldenhauer, Nikolai N Sluchanko, David Buhrke, Dmitry V Zlenko, Neslihan N Tavraz, Franz-Josef Schmitt, Peter Hildebrandt, Eugene G Maksimov, Thomas Friedrich
The photoswitchable orange carotenoid protein (OCP) is indispensable for cyanobacterial photoprotection by quenching phycobilisome fluorescence upon photoconversion from the orange OCP(O) to the red OCP(R) form. Cyanobacterial genomes frequently harbor, besides genes for orange carotenoid proteins (OCPs), several genes encoding homologs of OCP's N- or C-terminal domains (NTD, CTD). Unlike the well-studied NTD homologs, called Red Carotenoid Proteins (RCPs), the role of CTD homologs remains elusive. We show how OCP can be reassembled from its functional domains...
February 17, 2017: Photosynthesis Research
Aya Onishi, Shimpei Aikawa, Akihiko Kondo, Seiji Akimoto
Nitrogen is among the most important nutritious elements for photosynthetic organisms such as plants, algae, and cyanobacteria. Therefore, nitrogen depletion severely compromises the growth, development, and photosynthesis of these organisms. To preserve their integrity under nitrogen-depleted conditions, filamentous nitrogen-fixing cyanobacteria reduce atmospheric nitrogen to ammonia, and self-adapt by regulating their light-harvesting and excitation energy-transfer processes. To investigate the changes in the primary processes of photosynthesis, we measured the steady-state absorption and fluorescence spectra and time-resolved fluorescence spectra (TRFS) of whole filaments of the nitrogen-fixing cyanobacterium Anabaena variabilis at 77 K...
February 16, 2017: Photosynthesis Research
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