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https://www.readbyqxmd.com/read/28942523/overexpression-of-plastidic-maize-nadp-malate-dehydrogenase-zmnadp-mdh-in-arabidopsis-thaliana-confers-tolerance-to-salt-stress
#1
Deepika Kandoi, Sasmita Mohanty, Baishnab C Tripathy
The plastidic C4 Zea mays NADP-malate dehydrogenase (ZmNADP-MDH), responsible for catalysis of oxaloacetate to malate, was overexpressed in Arabidopsis thaliana to assess its impact on photosynthesis and tolerance to salinity stress. Different transgenic lines were produced having ~3-6-fold higher MDH protein abundance and NADP-MDH enzyme activity than vector control. The overexpressors had similar chlorophyll, carotenoid, and protein content as that of vector control. Their photosynthetic electron transport rates, carbon assimilation rate, and consequently fresh weight and dry weight were almost similar...
September 24, 2017: Protoplasma
https://www.readbyqxmd.com/read/28924017/in-silico-analysis-of-the-regulation-of-the-photosynthetic-electron-transport-chain-in-c3-plants
#2
Alejandro Morales, Xinyou Yin, Jeremy Harbinson, Steven Michiel Driever, Jaap Molenaar, David M Kramer, Paul Struik
We present a new simulation model of the reactions in the photosynthetic electron transport chain of C3 species. We show that including recent insights about the regulation of the thylakoid proton motive force, ATP/NADPH balancing mechanisms (cyclic and non-cyclic alternative electron transport), and regulation of Rubisco activity, leads to emergent behaviors that may affect the operation and regulation of photosynthesis under different dynamic environmental conditions. The model was parameterized with experimental results in the literature, with a focus on Arabidopsis thaliana...
September 18, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28922769/psb33-sustains-photosystem-ii-d1-protein-under-fluctuating-light-conditions
#3
Rikard Fristedt, Andrea Trotta, Marjaana Suorsa, Anders K Nilsson, Roberta Croce, Eva-Mari Aro, Björn Lundin
On Earth, solar irradiance varies as the sun rises and sets over the horizon, and sunlight is thus in constant fluctuation, following a slow dark-low-high-low-dark curve. Optimal plant growth and development are dependent on the capacity of plants to acclimate and regulate photosynthesis in response to these changes of light. Little is known of regulative processes for photosynthesis during nocturnal events. The nucleus-encoded plant lineage-specific protein PSB33 has been described as stabilizing the photosystem II complex, especially under light stress conditions, and plants lacking PSB33 have a dysfunctional state transition...
July 10, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28918549/loss-of-lhci-system-affects-lhcii-re-distribution-between-thylakoid-domains-upon-state-transitions
#4
Mauro Bressan, Roberto Bassi, Luca Dall'Osto
LHCI, the peripheral antenna system of Photosystem I, includes four light-harvesting proteins (Lhca1-Lhca4) in higher plants, all of which are devoid in the Arabidopsis thaliana knock-out mutant ΔLhca. PSI absorption cross-section was reduced in the mutant, thus affecting the redox balance of the photosynthetic electron chain and resulting in a more reduced PQ with respect to the wild type. ΔLhca plants developed compensatory response by enhancing LHCII binding to PSI. However, the amplitude of state transitions, as measured from changes of chlorophyll fluorescence in vivo, was unexpectedly low than the high level of PSI-LHCII supercomplex established...
September 16, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28916593/carnosic-acid-and-carnosol-two-major-antioxidants-of-rosemary-act-through-different-mechanisms
#5
Margot Loussouarn, Anja Krieger-Liszkay, Ljubica Svilar, Antoine Bily, Simona Birtic, Michel Havaux
Carnosic acid, a phenolic diterpene specific of the Lamiaceae family, is highly abundant in rosemary species. Despite numerous industrial and medicinal/pharmaceutical applications of its antioxidative features, this compound in planta and its antioxidant mechanism have received little attention, except a few studies of rosemary plants under natural conditions. In vitro analyses, using HPLC-UV and luminescence imaging, revealed that carnosic acid and its major oxidized derivative, carnosol, protect lipids from oxidation...
September 15, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28911055/pyrenoid-loss-in-chlamydomonas-reinhardtii-causes-limitations-in-co2-supply-but-not-thylakoid-operating-efficiency
#6
Oliver D Caspari, Moritz T Meyer, Dimitri Tolleter, Tyler M Wittkopp, Nik J Cunniffe, Tracy Lawson, Arthur R Grossman, Howard Griffiths
The pyrenoid of the unicellular green alga Chlamydomonas reinhardtii is a microcompartment situated in the centre of the cup-shaped chloroplast, containing up to 90% of cellular Rubisco. Traversed by a network of dense, knotted thylakoid tubules, the pyrenoid has been proposed to influence thylakoid biogenesis and ultrastructure. Mutants that are unable to assemble a pyrenoid matrix, due to expressing a vascular plant version of the Rubisco small subunit, exhibit severe growth and photosynthetic defects and have an ineffective carbon-concentrating mechanism (CCM)...
June 1, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28911053/co-ordination-of-ndh-and-cup-proteins-in-co2-uptake-in-cyanobacterium-synechocystis-sp-pcc-6803
#7
Xunling Han, Nan Sun, Min Xu, Hualing Mi
High and low affinity CO2-uptake systems containing CupA (NDH-1MS) and CupB (NDH-1MS'), respectively, have been identified in Synechocystis sp. PCC 6803, but it is yet unknown how the complexes function in CO2 uptake. In this work, we found that deletion of cupB significantly lowered the growth of cells, and deletion of both cupA and cupB seriously suppressed the growth below pH 7.0 even under 3% CO2. The rate of photosynthetic oxygen evolution was decreased slightly by deletion of cupA but significantly by deletion of cupB and more severely by deletion of both cupA and cupB, especially in response to changed pH conditions under 3% CO2...
June 1, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28877503/one-ring-two-membranes-im30-ring-complex-and-the-thylakoid-membrane-fusion
#8
Diana Wolf
Direct membrane fusion in chloroplasts and cyanobacteria is triggered by IM30 protein oligomers, but so far the exact mechanism of membrane binding has remained obscure. In this issue of Structure, Saur et al. (2017) describe the detailed structure of Janus-faced IM30 rings crucial for thylakoid membrane fusion and membrane layer architecture.
September 5, 2017: Structure
https://www.readbyqxmd.com/read/28874535/a-chloroplast-thylakoid-lumen-protein-is-required-for-proper-photosynthetic-acclimation-of-plants-under-fluctuating-light-environments
#9
Jun Liu, Robert L Last
Despite our increasingly sophisticated understanding of mechanisms ensuring efficient photosynthesis under laboratory-controlled light conditions, less is known about the regulation of photosynthesis under fluctuating light. This is important because-in nature-photosynthetic organisms experience rapid and extreme changes in sunlight, potentially causing deleterious effects on photosynthetic efficiency and productivity. Here we report that the chloroplast thylakoid lumenal protein MAINTENANCE OF PHOTOSYSTEM II UNDER HIGH LIGHT 2 (MPH2; encoded by At4g02530) is required for growth acclimation of Arabidopsis thaliana plants under controlled photoinhibitory light and fluctuating light environments...
September 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28872312/light-adaptation-in-phycobilisome-antennas-influence-on-the-rod-length-and-structural-arrangement
#10
Aurélia Chenu, Nir Keren, Yossi Paltiel, Reinat Nevo, Ziv Reich, Jianshu Cao
Phycobilisomes, the light-harvesting antennas of cyanobacteria, can adapt to a wide range of environments thanks to a composition and function response to stress conditions. We study how structural changes influence excitation transfer in these supercomplexes. Specifically, we show the influence of the rod length on the photon absorption and subsequent excitation transport to the core. Despite the fact that the efficiency of individual disks on the rod decreases with increasing rod length, we find an optimal length for which the average rod efficiency is maximal...
September 25, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28865165/spectroanalysis-in-native-gels-sing-rapid-spectral-analysis-of-pigmented-thylakoid-membrane-complexes-separated-by-clear-native-page
#11
Ben Lucker, Eliezer Schwartz, Sebastian Kuhlgert, Elisabeth Ostendorf, David M Kramer
Photosynthetic organisms rapidly adjust the capture, transfer and utilization of light energy to optimize the efficiency of photosynthesis and avoid photodamage. These adjustments involve fine tuning of expression levels and mutual interactions among electron/proton transfer components and their associated light harvesting antenna. Detailed studies of these interactions and their dynamics have been hindered by the low throughput and resolution of currently available research tools, which involve laborious isolation, separation and characterization steps...
September 2, 2017: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/28857741/in-vivo-experiments-do-not-support-the-charge-zipper-model-for-tat-translocase-assembly
#12
Felicity Alcock, Merel Pm Damen, Jesper Levring, Ben C Berks
The twin-arginine translocase (Tat) transports folded proteins across the bacterial cytoplasmic membrane and the plant thylakoid membrane. The Tat translocation site is formed by substrate-triggered oligomerization of the protein TatA. Walther and co-workers have proposed a structural model for the TatA oligomer in which TatA monomers self-assemble using electrostatic 'charge zippers' (Cell (2013) 132: 15945). This model was supported by in vitro analysis of the oligomeric state of TatA variants containing charge-inverting substitutions...
August 31, 2017: ELife
https://www.readbyqxmd.com/read/28856519/osppr6-a-pentatricopeptide-repeat-protein-involved-in-editing-and-splicing-chloroplast-rna-is-required-for-chloroplast-biogenesis-in-rice
#13
Jianpeng Tang, Wenwei Zhang, Kai Wen, Gaoming Chen, Juan Sun, Yunlu Tian, Weijie Tang, Jun Yu, Hongzhou An, Tingting Wu, Fei Kong, William Terzaghi, Chunming Wang, Jianmin Wan
OsPPR6, a pentatricopeptide repeat protein involved in editing and splicing chloroplast RNA, is required for chloroplast biogenesis in rice. The chloroplast has its own genetic material and genetic system, but it is also regulated by nuclear-encoded genes. However, little is known about nuclear-plastid regulatory mechanisms underlying early chloroplast biogenesis in rice. In this study, we isolated and characterized a mutant, osppr6, that showed early chloroplast developmental defects leading to albino leaves and seedling death...
August 30, 2017: Plant Molecular Biology
https://www.readbyqxmd.com/read/28855679/pea-psii-lhcii-supercomplexes-form-pairs-by-making-connections-across-the-stromal-gap
#14
Pascal Albanese, Roberto Melero, Benjamin D Engel, Alessandro Grinzato, Paola Berto, Marcello Manfredi, Angelica Chiodoni, Javier Vargas, Carlos Óscar Sánchez Sorzano, Emilio Marengo, Guido Saracco, Giuseppe Zanotti, Jose-Maria Carazo, Cristina Pagliano
In higher plant thylakoids, the heterogeneous distribution of photosynthetic protein complexes is a determinant for the formation of grana, stacks of membrane discs that are densely populated with Photosystem II (PSII) and its light harvesting complex (LHCII). PSII associates with LHCII to form the PSII-LHCII supercomplex, a crucial component for solar energy conversion. Here, we report a biochemical, structural and functional characterization of pairs of PSII-LHCII supercomplexes, which were isolated under physiologically-relevant cation concentrations...
August 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28835225/specificity-versus-redundancy-in-the-rap2-4-transcription-factor-family-of-arabidopsis-thaliana-transcriptional-regulation-of-genes-for-chloroplast-peroxidases
#15
Radoslaw Rudnik, Jote Tafese Bulcha, Elena Reifschneider, Ulrike Ellersiek, Margarete Baier
BACKGROUND: The Arabidopsis ERFIb / RAP2.4 transcription factor family consists of eight members with highly conserved DNA binding domains. Selected members have been characterized individually, but a systematic comparison is pending. The redox-sensitive transcription factor RAP2.4a mediates chloroplast-to-nucleus redox signaling and controls induction of the three most prominent chloroplast peroxidases, namely 2-Cys peroxiredoxin A (2CPA) and thylakoid- and stromal ascorbate peroxidase (tAPx and sAPx)...
August 23, 2017: BMC Plant Biology
https://www.readbyqxmd.com/read/28834071/enhanced-photophosphorylation-of-chloroplast-entrapping-long-lived-photoacid
#16
Youqian Xu, Jinbo Fei, Guangle Li, Tingting Yuan, Yue Li, Chenlei Wang, Xianbao Li, Junbai Li
Enhancing solar energy conversion efficiency is very important for developing renewable energy, protecting the environment and producing agricultural products. We demonstrate here that photophosphorylation is enhanced efficiently by coupling artificial photoacid generators (PAGs) with chloroplasts. The encapsulation of small-molecule long-lived PAGs in the thylakoid lumen is improved greatly by ultrasonication. Under visible light irradiation, a fast intramolecular photoreaction of the PAG occurs and produces many protons, remarkably enhancing the proton gradient in situ...
August 18, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28829780/proteomic-analysis-of-potentilla-fruticosa-l-leaves-by-itraq-reveals-responses-to-heat-stress
#17
Yingtian Guo, Zhi Wang, Xuelian Guan, Zenghui Hu, Ze Zhang, Jian Zheng, Yizeng Lu
High temperature is an important environmental factor that affects plant growth and crop yield. Potentilla fruticosa L. has a developed root system and characteristics of resistance to several stresses (e.g., high temperature, cold, drought) that are shared by native shrubs in the north and west of China. To investigate thermotolerance mechanisms in P. fruticosa, 3-year-old plants were subjected to a high temperature of 42°C for 1, 2, and 3 days respectively before analysis. Then, we studied changes in cell ultrastructure using electron microscopy and investigated physiological changes in the leaves of P...
2017: PloS One
https://www.readbyqxmd.com/read/28828567/relative-contributions-of-pgr5-and-ndh-dependent-photosystem-i-cyclic-electron-flow-in-the-generation-of-a-proton-gradient-in-arabidopsis-chloroplasts
#18
Rinya Kawashima, Ryoichi Sato, Kyohei Harada, Shinji Masuda
Respective contributions of PGR5- and NDH-dependent cyclic electron flows around photosystem I for generating the proton gradient across the thylakoid membrane are ~30 and ~5%. The proton concentration gradient across the thylakoid membrane (ΔpH) produced by photosynthetic electron transport is the driving force of ATP synthesis and non-photochemical quenching. Two types of electron transfer contribute to ΔpH formation: linear electron flow (LEF) and cyclic electron flow (CEF, divided into PGR5- and NDH-dependent pathways)...
August 21, 2017: Planta
https://www.readbyqxmd.com/read/28821758/how-to-achieve-tat-transport-with-alien-tata
#19
René Steffen Hauer, Roland Freudl, Julia Dittmar, Mario Jakob, Ralf Bernd Klösgen
TatA is an essential and structurally conserved component of all known Twin-arginine transport (Tat) machineries which are able to catalyse membrane transport of fully folded proteins. Here we have investigated if bacterial TatA, or chimeric pea/E. coli TatA derivatives, are capable of replacing thylakoidal TatA in function. While authentic E. coli TatA does not show any transport activity in thylakoid transport experiments, TatA chimeras comprising the transmembrane helix (TMH) of pea TatA are fully active...
August 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28821590/three-dimensional-analysis-of-chloroplast-structures-associated-with-virus-infection
#20
Xuejiao Jin, Zhihao Jiang, Kun Zhang, Pengfei Wang, Xiuling Cao, Ning Yue, Xueting Wang, Xuan Zhang, Yunqin Li, Dawei Li, Byung-Ho Kang, Yongliang Zhang
Chloroplasts are multifunctional organelles whose morphology is affected by environmental stresses. Although the three-dimensional (3D) architecture of thylakoid membranes has been reported previously, a 3D visualization of chloroplast under stress has not been explored. In this work, we used a positive-strand RNA [(+)RNA] virus, Barley stripe mosaic virus (BSMV) to observe chloroplast structural changes during infection by electron tomography (ET). The analyses revealed remodeling of the chloroplast membranes, characterized by the clustering of outer membrane-invaginated spherules in inner membrane-derived packets...
August 18, 2017: Plant Physiology
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