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https://www.readbyqxmd.com/read/28103400/the-sufbc2-d-complex-is-required-for-the-biogenesis-of-all-major-classes-of-plastid-fe-s-proteins
#1
Xueyun Hu, Yukako Kato, Akihiro Sumida, Ayumi Tanaka, Ryouichi Tanaka
Iron-sulfur (Fe-S) proteins play crucial roles in plastids, participating in photosynthesis and other metabolic pathways. Fe-S clusters are thought to be assembled on a scaffold complex composed of SUFB, SUFC and SUFD proteins. However, several additional proteins provide putative scaffold functions in plastids, and, therefore, the contribution of SUFB, C and D proteins to overall Fe-S assembly still remains unclear. In order to gain insights regarding Fe-S cluster biosynthesis in plastids, we analyzed the complex composed of SUFB, C and D in Arabidopsis by blue-native polyacrylamide gel electrophoresis...
January 19, 2017: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/28103045/photocurrent-generation-of-reconstituted-photosystem-ii-on-self-assembled-gold-film
#2
Mariko Miyachi, Shu Ikehira, Daiki Nishiori, Yoshinori Yamanoi, Masato Yamada, Masako Iwai, Tatsuya Tomo, Suleyman I Allakhverdiev, Hiroshi Nishihara
Photosystem II (PSII) modified gold electrodes were prepared by the deposition of PSII reconstituted with platinum nanoparticles (PtNPs) on Au electrodes. PtNPs modified with 1-[15-(3,5,6-trimethyl-1,4-benzoquinone-2-yl)]pentadecyl disulfide ((TMQ(CH2)15S)2) were incorporated into the QB site of PSII isolated from the thermophilic cyanobacterium, Thermosynechococcus elongatus. The reconstitution was confirmed by QA-reoxidation measurements. PSII reconstituted with PtNPs was deposited and integrated on a Au(111) surface modified with 4,4'-biphenyldithiol...
January 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28102753/chloroplastic-iron-sulfur-scaffold-protein-nfu3-is-essential-to-overall-plant-fitness
#3
Krishna Nath, James P O'Donnell, Yan Lu
A previous study showed that Nitrogen-Fixing-subunit-U-type protein NFU3 may act an iron-sulfur scaffold protein in the assembly and transfer of 4Fe-4S and 3Fe-4S clusters in the chloroplast. Examples of 4Fe-4S and 3Fe-4S-requiring proteins and complexes include Photosystem I (PSI), NAD(P)H dehydrogenase, and ferredoxin-dependent glutamine oxoglutarate aminotransferases. In this paper, the authors provided additional evidence for the role of NFU3 in 4Fe-4S and 3Fe-4S cluster assembly and transfer, as well as its role in overall plant fitness...
January 19, 2017: Plant Signaling & Behavior
https://www.readbyqxmd.com/read/28102667/two-different-structures-of-the-oxygen-evolving-complex-in-the-same-polypeptide-frameworks-of-photosystem-ii
#4
Ayako Tanaka, Yoshimasa Fukushima, Nobuo Kamiya
The oxygen-evolving complex (OEC) forms the heart of photosystem II (PSII) in photosynthesis. The crystal structure of PSII from Thermosynechococcus vulcanus has been reported at a resolution of 1.9 Å and at an averaged X-ray dose of 0.43 MGy. The OEC structure is suggested to be partially reduced to Mn(II) by EXAFS and DFT compu-tational studies. Recently, the "radiation-damage-free" struc-tures have been published at 1.95 Å resolution using XFEL, but reports continued to appear that the OEC is reduced to the S0-state of the Kok cycle...
January 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28099021/location-of-methanol-on-the-s2-state-mn-cluster-in-photosystem-ii-studied-by-proton-matrix-electron-nuclear-double-resonance
#5
Hiroki Nagashima, Hiroyuki Mino
Proton matrix electron nuclear double resonance (ENDOR) spectroscopy was performed in order to specify the location of the methanol molecule near the manganese cluster in photosystem II. Comparison of the ENDOR spectra in the presence of CH3OH and CD3OH revealed two pairs of hyperfine couplings, 1.15 MHz for A⊥ and 2.32 MHz for A∥, arising from the methyl group in methanol. Based on the crystal structure, the possible location of methanol close to the manganese cluster was discussed.
January 18, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28096192/integrated-physiological-proteomic-and-metabolomic-analysis-of-uv-stress-responses-and-adaptation-mechanisms-in-pinus-radiata
#6
Jesus Pascual, Maria Jesus Canal, Monica Escandon, Monica Meijon, Wolfram Weckwerth, Luis Valledor
Globally expected changes in environmental conditions, especially the increase of UV irradiation, necessitate extending our knowledge of the mechanisms mediating tree species adaptation to this stress. This is crucial for designing new strategies to maintain future forest productivity. Studies focused on environmentally realistic dosages of UV irradiation in forest species are scarce. Pinus sp. are commercially relevant trees and not much is known about their adaptation to UV. In this work, UV treatment and recovery of Pinus radiata plants with dosages mimicking future scenarios, based on current models of UV radiation, were performed in a time-dependent manner...
January 17, 2017: Molecular & Cellular Proteomics: MCP
https://www.readbyqxmd.com/read/28095301/imaging-the-photosystem-i-photosystem-ii-chlorophyll-ratio-inside-the-leaf
#7
Emilie Wientjes, John Philippi, Jan Willem Borst, Herbert van Amerongen
Oxygenic photosynthesis is driven by photosystems I (PSI) and II (PSII). In plants the number of chlorophylls of PSI versus PSII is adjusted to the light irradiance spectrum. On a timescale of days, this is regulated at the level of protein concentration. Instead, on a timescale of minutes, it is regulated by the dynamic association of light-harvesting complex II with either PSI or PSII. Thus far very diverse values have been reported for the PSI/PSII chlorophyll ratio, ranging from 0.54 to 1.4. The methods used require the isolation of chloroplasts and are time consuming...
January 14, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28088851/monitoring-the-reaction-process-during-the-s2%C3%A2-s3-transition-in-photosynthetic-water-oxidation-using-time-resolve-infrared-spectroscopy
#8
Hiroki Sakamoto, Tatsuki Shimizu, Ryo Nagao, Takumi Noguchi
Photosynthetic water oxidation performed at the Mn4CaO5 cluster in photosystem II plays a crucial role in energy production as electron and proton sources necessary for CO2 fixation. Molecular oxygen, a byproduct, is a source of the oxygenic atmosphere that sustains life on earth. However, the molecular mechanism of water oxidation is not yet well understood. In the reaction cycle of intermediates called S states, the S2→S3 transition is particularly important; it consists of multiple processes of electron transfer, proton release, and water insertion, and generates an intermediate leading to O-O bond formation...
January 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28088020/sulphur-alters-chromium-vi-toxicity-in-solanum-melongena-seedlings-role-of-sulphur-assimilation-and-sulphur-containing-antioxidants
#9
Madhulika Singh, Bishwajit Kumar Kushwaha, Samiksha Singh, Vipin Kumar, Vijay Pratap Singh, Sheo Mohan Prasad
The present study investigates modulation in hexavalent chromium [Cr(VI) 25 μM] toxicity by sulphur (S; 0.5, 1.0 and 1.5 mM S as low (LS), medium (MS) and high sulphur (HS), respectively) in Solanum melongena (eggplant) seedlings. Biomass accumulation (fresh and dry weights), photosynthetic pigments, photosynthetic oxygen evolution and S content were declined by Cr(VI) toxicity. Furthermore, fluorescence characteristics (JIP-test) were also affected by Cr(VI), but Cr(VI) toxicity on photosystem II photochemistry was ameliorated by HS treatment via reducing damaging effect on PS II reaction centre and its reduction side...
December 27, 2016: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/28079373/energetics-of-the-s2-state-spin-isomers-of-the-oxygen-evolving-complex-of-photosystem-ii
#10
David J Vinyard, Sahr Khan, Mikhail Askerka, Victor S Batista, Gary W Brudvig
The S2 redox intermediate of the oxygen-evolving complex in Photosystem II is present as two spin isomers. The S = 1/2 isomer gives rise to a multiline EPR signal at g = 2, while the S = 5/2 isomer exhibits a broad EPR signal at g = 4.1. The electronic structures of these isomers are known, but their role in the catalytic cycle of water oxidation remains unclear. We show that formation of the S = 1/2 state from the S = 5/2 state is exergonic at temperatures above 160 K. However, the S = 1/2 isomer decays to S1 more slowly than the S = 5/2 isomer...
January 12, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28078551/the-proteolysis-adaptor-nbla-binds-to-the-n-terminus-of-%C3%AE-phycocyanin-implications-for-the-mechanism-of-phycobilisome-degradation
#11
Amelia Y Nguyen, William P Bricker, Hao Zhang, Daniel A Weisz, Michael L Gross, Himadri B Pakrasi
Phycobilisome (PBS) complexes are massive light-harvesting apparati in cyanobacteria that capture and funnel light energy to the photosystem. PBS complexes are dynamically degraded during nutrient deprivation, which causes severe chlorosis, and resynthesized during nutrient repletion. PBS degradation occurs rapidly after nutrient step down, and is specifically triggered by non-bleaching protein A (NblA), a small proteolysis adaptor that facilitates interactions between a Clp chaperone and phycobiliproteins...
January 11, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28077273/reevaluating-the-mechanism-of-excitation-energy-regulation-in-iron-starved-cyanobacteria
#12
Hui-Yuan S Chen, Michelle Liberton, Himadri B Pakrasi, Dariusz M Niedzwiedzki
This paper presents spectroscopic investigations of IsiA, a chlorophyll a-binding membrane protein produced by cyanobacteria grown in iron-deficient environments. IsiA, if associated with photosystem I, supports photosystem I in light harvesting by efficiently transferring excitation energy. However, if separated from photosystem I, IsiA exhibits considerable excitation quenching observed as a substantial reduction of protein-bound chlorophyll a fluorescence lifetime. Previous spectroscopic studies suggested that carotenoids are involved in excitation energy dissipation and in addition play a second role in this antenna complex by supporting chlorophyll a in light harvesting by absorbing in the spectral range inaccessible for chlorophyll a and transferring excitation to chlorophylls...
January 8, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28076430/effects-of-zn-deficiency-and-bicarbonate-on-the-growth-and-photosynthetic-characteristics-of-four-plant-species
#13
Kuan Zhao, Yanyou Wu
Calcareous soils are characterized by low nutrient contents, high bicarbonate (HCO3-) content, and high alkalinity. The effects of HCO3- addition under zinc-sufficient (+Zn) and zinc-deficient (-Zn) conditions on the growth and photosynthetic characteristics of seedlings of two Moraceae species (Broussonetia papyrifera and Morus alba) and two Brassicaceae species (Orychophragmus violaceus and Brassica napus) were investigated. These four species were hydroponically grown in nutrient solution with 0 mM Zn (-Zn) or 0...
2017: PloS One
https://www.readbyqxmd.com/read/28058690/functions-of-chromophore-containing-domain-in-the-large-linker-lcm-polypeptide-of-phycobilisome
#14
I V Elanskaya, I A Kononova, E P Lukashev, Y V Bolychevtseva, M F Yanushin, I N Stadnichuk
In the large linker ArcE polypeptide of the phycobilisome (PBS) from the cyanobacterium Synechocystis sp. PCC 6803, the chromophore-containing 26-kDa domain was deleted with consequent disturbance of the main PBS functions. Phycobilisomes in mutant cells staying in contact with photosystem I cannot transfer energy to the photosystem II. Under the bright light conditions, the interaction of PBSs with the photoprotective orange carotenoid protein in the mutant was lost and the implementation of transition states 1 and 2 of the pigment apparatus was significantly reduced...
November 2016: Doklady. Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28044463/silver-nanoparticles-induced-reactive-oxygen-species-via-photosynthetic-energy-transport-imbalance-in-an-aquatic-plant
#15
Hong Sheng Jiang, Li Yan Yin, Na Na Ren, Su Ting Zhao, Zhi Li, Yongwei Zhi, Hui Shao, Wei Li, Brigitte Gontero
The rapid growth in silver nanoparticles (AgNPs) commercialization has increased environmental exposure, including aquatic ecosystem. It has been reported that the AgNPs have damaging effects on photosynthesis and induce oxidative stress, but the toxic mechanism of AgNPs is still a matter of debate. In the present study, on the model aquatic higher plant Spirodela polyrhiza, we found that AgNPs affect photosynthesis and significantly inhibit Photosystem II (PSII) maximum quantum yield (Fv/Fm) and effective quantum yield (ΦPSII)...
January 19, 2017: Nanotoxicology
https://www.readbyqxmd.com/read/28044099/structural-changes-correlated-with-magnetic-spin-state-isomorphism-in-the-s2-state-of-the-mn4cao5-cluster-in-the-oxygen-evolving-complex-of-photosystem-ii
#16
Ruchira Chatterjee, Guangye Han, Jan Kern, Sheraz Gul, Franklin D Fuller, Anna Garachtchenko, Iris Young, Tsu-Chien Weng, Dennis Nordlund, Roberto Alonso-Mori, Uwe Bergmann, Dimosthenis Sokaras, Makoto Hatakeyama, Vittal K Yachandra, Junko Yano
The Mn4CaO5 cluster in Photosystem II catalyzes the four-electron redox reaction of water oxidation in natural photosynthesis. This catalytic reaction cycles through four intermediate states (Si, i = 0 to 4), involving changes in the redox state of the four Mn atoms in the cluster. Recent studies suggest the presence and importance of isomorphous structures within the same redox/intermediate S-state. It is highly likely that geometric and electronic structural flexibility play a role in the catalytic mechanism...
August 1, 2016: Chemical Science
https://www.readbyqxmd.com/read/28043335/a-high-throughput-modified-als-activity-assay-for-cyperus-difformis-and-schoenoplectus-mucronatus-seedlings
#17
Rafael M Pedroso, Kassim Al-Khatib, Bradley D Hanson, Albert J Fischer
Cyperus difformis L. (CYPDI) and Schoenoplectus mucronatus (L.) Palla (SCHMU) are major weeds of California (CA) rice, where resistance to acetolactate synthase (ALS)-inhibitors was identified in several CYPDI and SCHMU populations that have also evolved resistance to photosystem II (PSII)-inhibiting herbicides. The mechanism of ALS resistance in these populations remains to be clarified but this information is crucial in a weed management program, especially in a scenario where resistance to multiple herbicides has been identified...
January 2017: Pesticide Biochemistry and Physiology
https://www.readbyqxmd.com/read/28042464/reactive-oxygen-species-in-iridium-based-oer-catalysts
#18
Verena Pfeifer, Travis E Jones, Sabine Wrabetz, Cyriac Massué, Juan J Velasco Vélez, Rosa Arrigo, Michael Scherzer, Simone Piccinin, Michael Hävecker, Axel Knop-Gericke, Robert Schlögl
Tremendous effort has been devoted towards elucidating the fundamental reasons for the higher activity of hydrated amorphous Ir(III/IV) oxyhydroxides (IrO x ) in the oxygen evolution reaction (OER) in comparison with their crystalline counterpart, rutile-type IrO2, by focusing on the metal oxidation state. Here we demonstrate that, through an analogy to photosystem II, the nature of this reactive species is not solely a property of the metal but is intimately tied to the electronic structure of oxygen. We use a combination of synchrotron-based X-ray photoemission and absorption spectroscopies, ab initio calculations, and microcalorimetry to show that holes in the O 2p states in amorphous IrO x give rise to a weakly bound oxygen that is extremely susceptible to nucleophilic attack, reacting stoichiometrically with CO already at room temperature...
November 18, 2016: Chemical Science
https://www.readbyqxmd.com/read/28039776/far-red-light-is-needed-for-efficient-photochemistry-and-photosynthesis
#19
Shuyang Zhen, Marc W van Iersel
The efficiency of monochromatic light to drive photosynthesis drops rapidly at wavelengths longer than 685nm. The photosynthetic efficiency of these longer wavelengths can be improved by adding shorter wavelength light, a phenomenon known as the Emerson enhancement effect. The reverse effect, the enhancement of photosynthesis under shorter wavelength light by longer wavelengths, however, has not been well studied and is often thought to be insignificant. We quantified the effect of adding far-red light (peak at 735nm) to red/blue or warm-white light on the photosynthetic efficiency of lettuce (Lactuca sativa)...
December 15, 2016: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28035956/changes-of-photosynthetic-behaviors-and-photoprotection-during-cell-transformation-and-astaxanthin-accumulation-in-haematococcus-pluvialis-grown-outdoors-in-tubular-photobioreactors
#20
Litao Zhang, Fang Su, Chunhui Zhang, Fengying Gong, Jianguo Liu
The cell transformation from green motile cells to non-motile cells and astaxanthin accumulation can be induced in the green alga Haematococcus pluvialis cultured outdoors. In the initial 3 d of incubation (cell transformation phase), light absorption and photosynthetic electron transport became more efficient. After five days of incubation (astaxanthin accumulation phase), the light absorption per active reaction center (ABS/RC) increased, but the efficiency of electron transport (ψo) and the quantum yield of electron transport (φEo) decreased with increased time, indicating that the capacity of photosynthetic energy utilization decreased significantly during astaxanthin accumulation, leading to an imbalance between photosynthetic light absorption and energy utilization...
December 26, 2016: International Journal of Molecular Sciences
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