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https://www.readbyqxmd.com/read/28230184/tobacco-vein-banding-mosaic-virus-6k2-protein-hijacks-nbpsbo1-for-virus-replication
#1
Chao Geng, Zhi-Yong Yan, De-Jie Cheng, Jin Liu, Yan-Ping Tian, Chang-Xiang Zhu, Hong-Yan Wang, Xiang-Dong Li
Chloroplast-bound vesicles are key components in viral replication complexes (VRCs) of potyviruses. The potyviral VRCs are induced by the second 6 kDa protein (6K2) and contain at least viral RNA and nuclear inclusion protein b. To date, no chloroplast protein has been identified to interact with 6K2 and involve in potyvirus replication. In this paper, we showed that the Photosystem II oxygen evolution complex protein of Nicotiana benthamiana (NbPsbO1) was a chloroplast protein interacting with 6K2 of Tobacco vein banding mosaic virus (TVBMV; genus Potyvirus) and present in the VRCs...
February 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28226223/progress-toward-a-molecular-mechanism-of-water-oxidation-in-photosystem-ii
#2
David J Vinyard, Gary W Brudvig
The active site of photosynthetic water oxidation is the oxygen-evolving complex (OEC) in the photosystem II (PSII) reaction center. The OEC is a Mn4CaO5 cluster embedded in the PSII protein matrix, and it cycles through redox intermediates known as Si states (i = 0-4). Significant progress has been made in understanding the inorganic and physical chemistry of states S0-S3 through experiment and theory. The chemical steps from S3 to S0 are more poorly understood, however, because the identity of the substrate water molecules and the mechanism of O-O bond formation are not well established...
February 2, 2017: Annual Review of Physical Chemistry
https://www.readbyqxmd.com/read/28226220/water-oxidation-mechanisms-of-metal-oxide-catalysts-by-vibrational-spectroscopy-of-transient-intermediates
#3
Miao Zhang, Heinz Frei
Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements...
February 22, 2017: Annual Review of Physical Chemistry
https://www.readbyqxmd.com/read/28223992/carbon-monoxide-is-involved-in-hydrogen-gas-induced-adventitious-root-development-in-cucumber-under-simulated-drought-stress
#4
Yue Chen, Meng Wang, Linli Hu, Weibiao Liao, Mohammed M Dawuda, Chunlan Li
Hydrogen gas (H2) and carbon monoxide (CO) are involved in plant growth and developmental processes and may induce plant tolerance to several stresses. However, the independent roles and interaction effect of H2 and CO in adventitious root development under drought conditions have still not received the needed research attention. We hypothesize that there exists crosstalk between H2 and CO during adventitious root development under drought stress. The results of our current study revealed that 50% (v/v) hydrogen-rich water (HRW), 500 μM Hemin (the CO donor) and 30% (w/v) CO aqueous solution apparently promoted the development of adventitious roots in cucumber explants (Cucumis Sativus L...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28219079/light-induced-structural-changes-and-the-site-of-o-o-bond-formation-in-psii-caught-by-xfel
#5
Michihiro Suga, Fusamichi Akita, Michihiro Sugahara, Minoru Kubo, Yoshiki Nakajima, Takanori Nakane, Keitaro Yamashita, Yasufumi Umena, Makoto Nakabayashi, Takahiro Yamane, Takamitsu Nakano, Mamoru Suzuki, Tetsuya Masuda, Shigeyuki Inoue, Tetsunari Kimura, Takashi Nomura, Shinichiro Yonekura, Long-Jiang Yu, Tomohiro Sakamoto, Taiki Motomura, Jing-Hua Chen, Yuki Kato, Takumi Noguchi, Kensuke Tono, Yasumasa Joti, Takashi Kameshima, Takaki Hatsui, Eriko Nango, Rie Tanaka, Hisashi Naitow, Yoshinori Matsuura, Ayumi Yamashita, Masaki Yamamoto, Osamu Nureki, Makina Yabashi, Tetsuya Ishikawa, So Iwata, Jian-Ren Shen
Photosystem II (PSII) is a huge membrane-protein complex consisting of 20 different subunits with a total molecular mass of 350 kDa for a monomer. It catalyses light-driven water oxidation at its catalytic centre, the oxygen-evolving complex (OEC). The structure of PSII has been analysed at 1.9 Å resolution by synchrotron radiation X-rays, which revealed that the OEC is a Mn4CaO5 cluster organized in an asymmetric, 'distorted-chair' form. This structure was further analysed with femtosecond X-ray free electron lasers (XFEL), providing the 'radiation damage-free' structure...
February 20, 2017: Nature
https://www.readbyqxmd.com/read/28217747/insights-into-photosystem-ii-from-isomorphous-difference-fourier-maps-of-femtosecond-x-ray-diffraction-data-and-quantum-mechanics-molecular-mechanics-structural-models
#6
REVIEW
Jimin Wang, Mikhail Askerka, Gary W Brudvig, Victor S Batista
Understanding structure-function relations in photosystem II (PSII) is important for the development of biomimetic photocatalytic systems. X-ray crystallography, computational modeling, and spectroscopy have played central roles in elucidating the structure and function of PSII. Recent breakthroughs in femtosecond X-ray crystallography offer the possibility of collecting diffraction data from the X-ray free electron laser (XFEL) before radiation damage of the sample, thereby overcoming the main challenge of conventional X-ray diffraction methods...
February 10, 2017: ACS Energy Lett
https://www.readbyqxmd.com/read/28217132/effects-of-environmental-conditions-on-the-fitness-penalty-in-herbicide-resistant-brachypodium-hybridum
#7
Eyal Frenkel, Maor Matzrafi, Baruch Rubin, Zvi Peleg
Herbicide-resistance mutations may impose a fitness penalty in herbicide-free environments. Moreover, the fitness penalty associated with herbicide resistance is not a stable parameter and can be influenced by ecological factors. Here, we used two Brachypodium hybridum accessions collected from the same planted forest, sensitive (S) and target-site resistance (TSR) to photosystem II (PSII) inhibitors, to study the effect of agro-ecological parameters on fitness penalty. Both accessions were collected in the same habitat, thus, we can assume that the genetic variance between them is relatively low...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28216046/inactivation-of-iron-sulfur-cluster-biogenesis-regulator-sufr-in-synechocystis-sp-pcc-6803-induces-unique-iron-dependent-protein-level-responses
#8
Linda Vuorijoki, Arjun Tiwari, Pauli Kallio, Eva-Mari Aro
BACKGROUND: Iron-sulfur (Fe-S) clusters are protein-bound cofactors associated with cellular electron transport and redox sensing, with multiple specific functions in oxygen-evolving photosynthetic cyanobacteria. The aim here was to elucidate protein-level effects of the transcriptional repressor SufR involved in the regulation of Fe-S cluster biogenesis in the cyanobacterium Synechocystis sp. PCC 6803. METHODS: The approach was to quantitate 94 pre-selected target proteins associated with various metabolic functions using SRM in Synechocystis...
February 16, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28213141/thermostability-of-photosystem-i-trimers-and-monomers-from-the-cyanobacterium-thermosynechococcus-elongatus
#9
Vladimir V Shubin, Irina V Terekhova, Yulia V Bolychevtseva, Eithar El-Mohsnawy, Matthias Rögner, Werner Mäntele, Marta J Kopczak, Enela Džafić
The performance of solar energy conversion into alternative energy sources in artificial systems highly depends on the thermostability of photosystem I (PSI) complexes Terasaki et al. (2007), Iwuchukwu et al. (2010), Kothe et al. (2013) . To assess the thermostability of PSI complexes from the thermophilic cyanobacterium Thermosynechococcus elongatus heating induced perturbations on the level of secondary structure of the proteins were studied. Changes were monitored by Fourier transform infrared (FT-IR) spectra in the mid-IR region upon slow heating (1°C per minute) of samples in D2O phosphate buffer (pD 7...
February 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28212707/astrobiological-implications-of-dim-light-phototrophy-in-deep-sea-red-clays
#10
Anindita Das, Tanya Singh, P A LokaBharathi, Prashant K Dhakephalkar, Sweta Mallik, Pranav R Kshirsagar, N H Khadge, B Nagender Nath, Satadru Bhattacharya, Aditya Kumar Dagar, Prabhjot Kaur, Dwijesh Ray, Anil D Shukla, Christabelle E G Fernandes, Sheryl O Fernandes, Tresa Remya A Thomas, Mamatha S S, Babu Shashikant Mourya, Ram Murti Meena
Red clays of Central Indian Basin (CIB) under influence of trace of Rodriguez Triple Junction exhibited chemoautotrophy, low temperature hydrothermal alterations and photoautotrophic potential. Seamount flank TVBC-08, hosting such signatures revealed dominance of aerobic anoxygenic phototroph Erythrobacter, with 93% of total 454 pyrosequencing tags. Subsequently, enrichments for both aerobic (Erythrobacter) and anaerobic anoxygenic phototrophs (green and purple sulphur bacteria) under red and white LED light illumination, with average irradiance 30...
February 2017: Life Sciences in Space Research
https://www.readbyqxmd.com/read/28210833/energy-transfer-in-anabaena-variabilis-filaments-adapted-to-nitrogen-depleted-and-nitrogen-enriched-conditions-studied-by-time-resolved-fluorescence
#11
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
https://www.readbyqxmd.com/read/28206823/the-effect-of-high-dose-ionizing-radiation-on-the-isolated-photobiont-of-the-astrobiological-model-lichen-circinaria-gyrosa
#12
Joachim Meeßen, Theresa Backhaus, Annette Brandt, Marina Raguse, Ute Böttger, Jean-Pierre de Vera, Rosa de la Torre
Lichen symbioses between fungi and algae represent successful life strategies to colonize the most extreme terrestrial habitats. Consequently, space exposure and simulation experiments have demonstrated lichens' high capacity for survival, and thus, they have become models in astrobiological research with which to discern the limits and limitations of terrestrial life. In a series of ground-based irradiation experiments, the STARLIFE campaign investigated the resistance of astrobiological model organisms to galactic cosmic radiation, which is one of the lethal stressors of extraterrestrial environments...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28206822/the-effect-of-high-dose-ionizing-radiation-on-the-astrobiological-model-lichen-circinaria-gyrosa
#13
Rosa de la Torre, Ana Zélia Miller, Beatriz Cubero, M Luisa Martín-Cerezo, Marina Raguse, Joachim Meeßen
The lichen Circinaria gyrosa is an astrobiological model defined by its high capacity of resistance to space conditions and to a simulated martian environment. Therefore, it became part of the currently operated BIOMEX experiment on board the International Space Station and the recent STARLIFE campaign to study the effects of four types of space-relevant ionizing radiation. The samples were irradiated with helium and iron ions at doses up to 2 kGy, with X-rays at doses up to 5 kGy and with γ rays at doses from 6 to 113 kGy...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28205062/gallium-ferredoxin-as-a-tool-to-study-the-effects-of-ferredoxin-binding-to-photosystem-i-without-ferredoxin-reduction
#14
Clara Mignée, Risa Mutoh, Anja Krieger-Liszkay, Genji Kurisu, Pierre Sétif
Reduction of ferredoxin by photosystem I (PSI) involves the [4Fe-4S] clusters FA and FB harbored by PsaC, with FB being the direct electron transfer partner of ferredoxin (Fd). Binding of the redox-inactive gallium ferredoxin to PSI was investigated by flash-absorption spectroscopy, studying both the P700(+) decay and the reduction of the native iron Fd in the presence of FdGa. FdGa binding resulted in a faster recombination between P700(+) and (FA, FB)(-), a slower electron escape from (FA, FB)(-) to exogenous acceptors, and a decreased amount of intracomplex FdFe reduction, in accordance with competitive binding between FdFe and FdGa...
February 15, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28199904/cyclic-electron-flow-may-provide-some-protection-against-psii-photoinhibition-in-rice-oryza-sativa-l-leaves-under-heat-stress
#15
Jemaa Essemine, Yi Xiao, Mingnan Qu, Hualing Mi, Xin-Guang Zhu
Previously we have shown that a quick down-regulation in PSI activity compares to that of PSII following short-term heat stress for two rice groups including C4023 and Q4149, studied herein. These accessions were identified to have different natural capacities in driving cyclic electron flow (CEF) around PSI; i.e., low CEF (lcef) and high CEF (hcef) for C4023 and Q4149, respectively. The aim of this study was to investigate whether these two lines have different mechanisms of protecting photosystem II from photodamage under heat stress...
January 30, 2017: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28199209/photosystem-ii-and-terminal-respiratory-oxidases-molecular-machines-operating-in-opposite-directions
#16
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/28193857/mass-spectrometry-based-cross-linking-study-shows-that-the-psb28-protein-binds-to-cytochrome-b559-in-photosystem-ii
#17
Daniel A Weisz, Haijun Liu, Hao Zhang, Sundarapandian Thangapandian, Emad Tajkhorshid, Michael L Gross, Himadri B Pakrasi
Photosystem II (PSII), a large pigment protein complex, undergoes rapid turnover under natural conditions. During assembly of PSII, oxidative damage to vulnerable assembly intermediate complexes must be prevented. Psb28, the only cytoplasmic extrinsic protein in PSII, protects the RC47 assembly intermediate of PSII and assists its efficient conversion into functional PSII. Its role is particularly important under stress conditions when PSII damage occurs frequently. Psb28 is not found, however, in any PSII crystal structure, and its structural location has remained unknown...
February 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28193046/probing-the-lysine-proximal-microenvironments-within-membrane-protein-complexes-by-active-dimethyl-labeling-and-mass-spectrometry
#18
Ye Zhou, Yue Wu, Mingdong Yao, Zheyi Liu, Jin Chen, Jun Chen, Lirong Tian, Guangye Han, Jian-Ren Shen, Fangjun Wang
Positively charged lysines are crucial to maintaining the native structures of proteins and protein complexes by forming hydrogen bonds and electrostatic interactions with their proximal amino acid residues. However, it is still a challenge to develop an efficient method for probing the active proximal microenvironments of lysines without changing their biochemical/physical properties. Herein, we developed an active covalent labeling strategy combined with mass spectrometry to systematically probe the lysine proximal microenvironments within membrane protein complexes (∼700 kDa) with high throughput...
December 20, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/28188782/lipid-and-carotenoid-cooperation-driven-adaptation-to-light-and-temperature-stress-in-synechocystis-sp-pcc6803
#19
Tomas Zakar, Eva Herman, Sindhujaa Vajravel, Laszlo Kovacs, Jana Knoppová, Josef Komenda, Ildiko Domonkos, Mihaly Kis, Zoltan Gombos, Hajnalka Laczko-Dobos
Polyunsaturated lipids are important components of photosynthetic membranes. Xanthophylls are the main photoprotective agents, can assist in protection against light stress, and are crucial in the recovery from photoinhibition. We generated the xanthophyll- and polyunsaturated lipid-deficient ROAD mutant of Synechocystis sp. PCC6803 (Synechocystis) in order to study the little-known cooperative effects of lipids and carotenoids (Cars). Electron microscopic investigations confirmed that in the absence of xanthophylls the S-layer of the cellular envelope is missing...
February 7, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28188547/structurally-conserved-channels-in-cyanobacterial-and-plant-photosystem-ii
#20
Naoki Sakashita, Hiroshi C Watanabe, Takuya Ikeda, Hiroshi Ishikita
In the cyanobacterial photosystem II (PSII), the O4-water chain in the D1 and CP43 proteins, a chain of water molecules that are directly H-bonded to O4 of the Mn4Ca cluster, is linked with a channel that connects the protein bulk surface along with a membrane-extrinsic protein subunit, PsbU (O4-PsbU channel). The cyanobacterial PSII structure also shows that the O1 site of the Mn4Ca cluster has a chain of H-bonded water molecules, which is linked with the channel that proceeds toward the bulk surface via PsbU and PsbV (O1-PsbU/V channel)...
February 10, 2017: Photosynthesis Research
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