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https://www.readbyqxmd.com/read/28332210/an-update-on-the-regulation-of-photosynthesis-by-thylakoid-ion-channels-and-transporters-in-arabidopsis
#1
Cornelia Spetea, Andrei Herdean, Guillaume Allorent, Luca Carraretto, Giovanni Finazzi, Ildikò Szabo
In natural variable environments, plants rapidly adjust photosynthesis for optimal balance between light absorption and utilization. There is increasing evidence suggesting that ion fluxes across the chloroplast thylakoid membrane play an important role in this regulation, by affecting the proton motive force, and consequently photosynthesis and thylakoid membrane ultrastructure. This minireview presents an update on the thylakoid ion channels and transporters characterized in Arabidopsis thaliana as being involved in these processes, as well as an outlook at the evolutionary conservation of their functions in other photosynthetic organisms...
March 23, 2017: Physiologia Plantarum
https://www.readbyqxmd.com/read/28323554/selective-nitration-of-psbo1-inhibits-oxygen-evolution-from-isolated-arabidopsis-thylakoid-membranes
#2
Misa Takahashi, Jun Shigeto, Atsushi Sakamoto, Hiromichi Morikawa
Treatment of isolated Arabidopsis thaliana thylakoid membranes with nitrogen dioxide (NO2) induces selective nitration of the tyrosine residue at the ninth amino acid ((9)Tyr) of PsbO1. This selective nitration is triggered by light and is inhibited by photosynthetic electron transport inhibitors. Therefore, we postulated that, similar to (161)Tyr of D1 (Yz), (9)Tyr of PsbO1 is redox active and is selectively oxidized by photosynthetic electron transport in response to illumination to a tyrosyl radical that is highly susceptible to nitration...
March 21, 2017: Plant Signaling & Behavior
https://www.readbyqxmd.com/read/28318016/the-transporter-synpam71-is-located-in-the-plasma-membrane-and-thylakoids-and-mediates-manganese-tolerance-in-synechocystis-pcc6803
#3
Chiara Gandini, Sidsel Birkelund Schmidt, Søren Husted, Anja Schneider, Dario Leister
Manganese (Mn) is an essential constituent of photosystem II (PSII) and therefore indispensable for oxygenic photosynthesis. Very little is known about how Mn is transported, delivered and retained in photosynthetic cells. Recently, the thylakoid-localized transporter PAM71 has been linked to chloroplast Mn homeostasis in Arabidopsis thaliana. Here, we characterize the function of its homolog in Synechocystis (SynPAM71). We used a loss-of-function line (ΔSynPAM71), wild-type (WT) cells exposed to Mn stress and strains expressing a tagged variant of SynPAM71 to characterize the role of SynPAM71 in cyanobacterial Mn homeostasis...
March 20, 2017: New Phytologist
https://www.readbyqxmd.com/read/28317130/influence-of-thylakoid-membrane-lipids-on-the-structure-of-aggregated-light-harvesting-complexes-of-the-diatom-thalassiosira-pseudonana-and-the-green-alga-mantoniella-squamata
#4
Susann Schaller-Laudel, Dariusz Latowski, Małgorzata Jemioła-Rzemińska, Kazimierz Strzałka, Sebastian Daum, Kirsten Bacia, Christian Wilhelm, Reimund Goss
The study investigated the effect of the thylakoid membrane lipids monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulphoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG) on the structure of two algal light-harvesting complexes (LHC). In contrast to higher plants whose thylakoid membranes are characterized by an enrichment of the neutral galactolipids MGDG and DGDG, both the green alga Mantoniella squamata and the centric diatom Thalassiosira pseudonana contain membranes with a high content of the negatively charged lipids SQDG and PG...
March 20, 2017: Physiologia Plantarum
https://www.readbyqxmd.com/read/28303390/the-hydroperoxide-lyase-branch-of-the-oxylipin-pathway-protects-against-photoinhibition-of-photosynthesis
#5
Tatyana Savchenko, Denis Yanykin, Andrew Khorobrykh, Vasily Terentyev, Vyacheslav Klimov, Katayoon Dehesh
This study describes a new role for hydroperoxide lyase branch of oxylipin biosynthesis pathway in protecting photosynthetic apparatus under high light conditions. Lipid-derived signaling molecules, oxylipins, produced by a multi-branch pathway are central in regulation of a wide range of functions. The two most known branches, allene oxide synthase (AOS) and 13-hydroperoxide lyase (HPL) pathways, are best recognized as producers of defense compounds against biotic challenges. In the present work, we examine the role of these two oxylipin branches in plant tolerance to the abiotic stress, namely excessive light...
March 16, 2017: Planta
https://www.readbyqxmd.com/read/28295753/identification-of-stn7-stn8-kinase-targets-reveals-connections-between-electron-transport-metabolism-and-gene-expression
#6
Anna Schönberg, Anja Rödiger, Wiebke Mehwald, Johann Galonska, Gideon Christ, Stefan Helm, Domenika Thieme, Petra Majovsky, Wolfgang Hoehenwarter, Sacha Baginsky
The thylakoid-associated kinases STN7 and STN8 are involved in short- and long-term acclimation of photosynthetic electron transport to changing light conditions. Here we report the identification of STN7/STN8 in vivo targets that connect photosynthetic electron transport with metabolism and gene expression. Comparative phosphoproteomics with the stn7 and stn8 single and double mutants identified two proteases, one RNA-binding protein, a ribosomal protein, the large subunit of rubisco and a ferredoxin-NADP reductase as targets for the thylakoid-associated kinases...
March 14, 2017: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/28286296/snowy-cotyledon-2-promotes-chloroplast-development-and-has-a-role-in-leaf-variegation-in-both-lotus-japonicus-and-arabidopsis-thaliana
#7
Nicola Zagari, Omar Sandoval-Ibañez, Niels Sandal, Junyi Su, Manuel Rodriguez-Concepcion, Jens Stougaard, Mathias Pribil, Dario Leister, Pablo Pulido
Plants contain various factors that transiently interact with subunits or intermediates of the thylakoid multiprotein complexes, promoting their stable association and integration. Hence, assembly factors are essential for chloroplast development and the transition from heterotrophic to phototrophic growth. Snowy cotyledon 2 (SCO2) is a DNAJ-like protein involved in thylakoid membrane biogenesis, and it interacts with the light-harvesting chlorophyll-binding protein LHCB1. In Arabidopsis thaliana, SCO2 function was described to be restricted to cotyledons, but here we show that in Lotus japonicus absence of SCO2 results not only in paler cotyledons but also in variegated true leaves...
March 9, 2017: Molecular Plant
https://www.readbyqxmd.com/read/28283981/the-effects-of-lead-stress-on-photosynthetic-function-and-chloroplast-ultrastructure-of-robinia-pseudoacacia-seedlings
#8
Jian Zhou, Zeping Jiang, Jie Ma, Lifeng Yang, Yuan Wei
In this experiment, the effects of different lead (Pb) concentrations (0, 200, 600, 1000, 1400 mg kg(-1)) on photosynthesis and chlorophyll fluorescence in Robinia pseudoacacia seedlings were examined. As Pb concentration increased, chlorophyll a, chlorophyll b, total chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance (g s), and mesophyll intercellular carbon dioxide concentration were gradually reduced. Maximal photochemical efficiency, photochemical quenching, and quantum yield also decreased...
March 11, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28261232/crp1-protein-dis-similarities-between-arabidopsis-thaliana-and-zea-mays
#9
Roberto Ferrari, Luca Tadini, Fabio Moratti, Marie-Kristin Lehniger, Alex Costa, Fabio Rossi, Monica Colombo, Simona Masiero, Christian Schmitz-Linneweber, Paolo Pesaresi
Biogenesis of chloroplasts in higher plants is initiated from proplastids, and involves a series of processes by which a plastid able to perform photosynthesis, to synthesize amino acids, lipids, and phytohormones is formed. All plastid protein complexes are composed of subunits encoded by the nucleus and chloroplast genomes, which require a coordinated gene expression to produce the correct concentrations of organellar proteins and to maintain organelle function. To achieve this, hundreds of nucleus-encoded factors are imported into the chloroplast to control plastid gene expression...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28258045/fine-tuning-transmission-electron-microscopy-methods-to-evaluate-the-cellular-architecture-of-ulvacean-seaweeds-chlorophyta
#10
D R Farias, C Simioni, E Poltronieri, Z L Bouzon, C K Macleod
Chemical fixation is a critical step in the analysis of the ultrastructure of seaweeds because the wrong approach can compromise the ability to distinguish fine-scale cellular composition. Fixation agents, fixation time and type of tissue are important factors to consider for transmission electron microscopy (TEM), and not every protocol is suitable for all cell types. We evaluated a range of fixation agents, post-fixation time and dehydration solutions to determine a TEM protocol for seaweeds in the Family Ulvaceae...
February 20, 2017: Micron: the International Research and Review Journal for Microscopy
https://www.readbyqxmd.com/read/28256000/involvement-of-the-chloroplast-plastoquinone-pool-in-the-mehler-reaction
#11
Daria V Vetoshkina, Boris N Ivanov, Ivan I Proskuryakov, Maria M Borisova-Mubarakshina
Light-dependent oxygen reduction in the photosynthetic electron transfer chain, i.e. the Mehler reaction, has been studied using isolated pea thylakoids. The role of the plastoquinone pool in the Mehler reaction was investigated in the presence of DNP-INT, the inhibitor of plastohydroquinone oxidation by cytochrome b6/f complex. Oxygen reduction rate in the presence of DNP-INT was higher than in the absence of the inhibitor in low light at pH 6.5 and 7.6, showing that the capacity of the plastoquinone pool to reduce molecular oxygen in this case exceeded that of the entire electron transfer chain...
March 3, 2017: Physiologia Plantarum
https://www.readbyqxmd.com/read/28251441/carotenogenic-response-in-photosynthetic-organisms-a-colorful-story
#12
REVIEW
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
https://www.readbyqxmd.com/read/28248295/structure-of-the-plant-photosystem-i-supercomplex-at-2-6%C3%A2-%C3%A3-resolution
#13
Yuval Mazor, Anna Borovikova, Ido Caspy, Nathan Nelson
Four elaborate membrane complexes carry out the light reaction of oxygenic photosynthesis. Photosystem I (PSI) is one of two large reaction centres responsible for converting light photons into the chemical energy needed to sustain life. In the thylakoid membranes of plants, PSI is found together with its integral light-harvesting antenna, light-harvesting complex I (LHCI), in a membrane supercomplex containing hundreds of light-harvesting pigments. Here, we report the crystal structure of plant PSI-LHCI at 2...
March 1, 2017: Nature Plants
https://www.readbyqxmd.com/read/28237493/low-ph-induced-reversible-reorganizations-of-chloroplast-thylakoid-membranes-as-revealed-by-small-angle-neutron-scattering
#14
Renáta Ünnep, Ottó Zsiros, Zsolt Hörcsik, Márton Markó, Anjana Jajoo, Joachim Kohlbrecher, Győző Garab, Gergely Nagy
Energization of thylakoid membranes brings about the acidification of the lumenal aqueous phase, which activates important regulatory mechanisms. Earlier Jajoo and coworkers (2014 FEBS Lett. 588:970) have shown that low pH in isolated plant thylakoid membranes induces changes in the excitation energy distribution between the two photosystems. In order to elucidate the structural background of these changes, we used small-angle neutron scattering on thylakoid membranes exposed to low p(2)H (pD) and show that gradually lowering the p(2)H from 8...
February 22, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28223511/a-signal-sequence-suppressor-mutant-that-stabilizes-an-assembled-state-of-the-twin-arginine-translocase
#15
Qi Huang, Felicity Alcock, Holger Kneuper, Justin C Deme, Sarah E Rollauer, Susan M Lea, Ben C Berks, Tracy Palmer
The twin-arginine protein translocation (Tat) system mediates transport of folded proteins across the cytoplasmic membrane of bacteria and the thylakoid membrane of chloroplasts. The Tat system of Escherichia coli is made up of TatA, TatB, and TatC components. TatBC comprise the substrate receptor complex, and active Tat translocases are formed by the substrate-induced association of TatA oligomers with this receptor. Proteins are targeted to TatBC by signal peptides containing an essential pair of arginine residues...
March 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28219973/sulfoquinovose-in-the-biosphere-occurrence-metabolism-and-functions
#16
REVIEW
Ethan D Goddard-Borger, Spencer J Williams
The sulfonated carbohydrate sulfoquinovose (SQ) is produced in quantities estimated at some 10 billion tonnes annually and is thus a major participant in the global sulfur biocycle. SQ is produced by most photosynthetic organisms and incorporated into the sulfolipid sulfoquinovosyl diacylglycerol (SQDG), as well as within some archaea for incorporation into glycoprotein N-glycans. SQDG is found mainly within the thylakoid membranes of the chloroplast, where it appears to be important for membrane structure and function and for optimal activity of photosynthetic protein complexes...
February 20, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28213560/identification-of-putative-substrates-of-sec2-a-chloroplast-inner-envelope-translocase
#17
Yubing Li, Jonathan R Martin, Giovanni A Aldama, Donna E Fernandez, Kenneth Cline
Most chloroplast proteins are synthesized in the cytosol and imported into chloroplasts. Many imported proteins are further targeted to the thylakoid membrane and lumen by the SEC1, TAT or SRP/ALB3 translocases. Others are targeted to the inner chloroplast envelope membrane by un-described translocase(s). Recently, a second SEC system (SEC2) consisting of SCY2, SECE2, and SECA2 was found in the chloroplast envelope. Null mutants of SCY2 in Arabidopsis exhibit a severe embryo lethal phenotype. To investigate the function of SEC2 system in plants, we used inducible RNAi to knockdown SCY2 in Arabidopsis...
February 17, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28199209/photosystem-ii-and-terminal-respiratory-oxidases-molecular-machines-operating-in-opposite-directions
#18
Sergey A Siletsky, Vitaliy B Borisov, Mahir D Mamedov
In the thylakoid membrane of green plants, cyanobacteria and algae, photosystem II (PSII) uses light energy to split water and generate molecular oxygen. In the opposite process of the biochemical transformation of dioxygen, in heterotrophs, the terminal respiratory oxidases (TRO) are at the end of the respiratory chain in mitochondria and in plasma membrane of many aerobic bacteria reducing dioxygen back to water. Despite the different sources of free energy (light or oxidation of the substrates), energy conversion by these enzymes is based on the spatial organization of enzymatic reactions in which the conversion of water to dioxygen (and vice versa) involves the transfer of protons and electrons in opposite directions across the membrane, which is accompanied by generation of proton-motive force...
March 1, 2017: Frontiers in Bioscience (Landmark Edition)
https://www.readbyqxmd.com/read/28194920/specific-interaction-between-redox-phospholipid-polymers-and-plastoquinone-in-photosynthetic-electron-transport-chain
#19
Kenya Tanaka, Masahiro Kaneko, Masahito Ishikawa, Souichiro Kato, Hidehiro Ito, Toshiaki Kamachi, Kazuhide Kamiya, Shuji Nakanishi
Redox phospholipid polymers added in culture media are known to be capable of extracting electrons from living photosynthetic cells across bacterial cell membranes with high cytocompatibility. In the present study, we aimed to identify the intracellular redox species that transfers electrons to the polymers. The open-circuit electrochemical potential of an electrolyte containing the redox polymer and extracted thylakoid membranes shifted to positive (or negative) under light irradiation, when an electron transport inhibitor specific for the upstream (or downstream) of plastoquinone in the photosynthetic electron transport chain was added...
February 13, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28194795/diversity-of-winter-photoinhibitory-responses-a-case-study-in-co-occurring-lichens-mosses-herbs-and-woody-plants-from-subalpine-environments
#20
Fátima Míguez, Beatriz Fernández-Marín, José-María Becerril, José-Ignacio García-Plazaola
Winter evergreens living in mountainous areas have to withstand a harsh combination of high light levels and low temperatures in wintertime. In response, evergreens can activate a photoprotective process that consists of the down-regulation of photosynthetic efficiency, referred to as winter photoinhibition (WPI). WPI has been studied mainly in woody evergreens and crops even when, in many instances, other functional groups such as lichens or bryophytes dominate in alpine and boreal habitats. Thus, we aimed to (1) assess the occurrence of WPI within overwintering evergreens comprising woody species, herbs, mosses and lichens; (2) compare the recovery kinetics among those groups; and (3) clarify the role of thylakoid proteins and pigments in both processes: WPI and recovery...
February 14, 2017: Physiologia Plantarum
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