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Photosynthesis Research

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https://www.readbyqxmd.com/read/28808836/excitation-transfer-and-trapping-kinetics-in-plant-photosystem-i-probed-by-two-dimensional-electronic-spectroscopy
#1
Parveen Akhtar, Cheng Zhang, Zhengtang Liu, Howe-Siang Tan, Petar H Lambrev
Photosystem I is a robust and highly efficient biological solar engine. Its capacity to utilize virtually every absorbed photon's energy in a photochemical reaction generates great interest in the kinetics and mechanisms of excitation energy transfer and charge separation. In this work, we have employed room-temperature coherent two-dimensional electronic spectroscopy and time-resolved fluorescence spectroscopy to follow exciton equilibration and excitation trapping in intact Photosystem I complexes as well as core complexes isolated from Pisum sativum...
August 14, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28795265/the-stress-induced-scp-hlip-family-of-small-light-harvesting-like-proteins-scpabcde-protects-photosystem-ii-from-photoinhibitory-damages-in-the-cyanobacterium-synechocystis-sp-pcc-6803
#2
Tania Tibiletti, Ateeq Ur Rehman, Imre Vass, Christiane Funk
Small CAB-like proteins (SCPs) are single-helix light-harvesting-like proteins found in all organisms performing oxygenic photosynthesis. We investigated the effect of growth in moderate salt stress on these stress-induced proteins in the cyanobacterium Synechocystis sp. PCC 6803 depleted of Photosystem I (PSI), which expresses SCPs constitutively, and compared these cells with a PSI-less/ScpABCDE(-) mutant. SCPs, by stabilizing chlorophyll-binding proteins and Photosystem II (PSII) assembly, protect PSII from photoinhibitory damages, and in their absence electrons accumulate and will lead to ROS formation...
August 9, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28755150/picosecond-excitation-energy-transfer-of-allophycocyanin-studied-in-solution-and-in-crystals
#3
Reza Ranjbar Choubeh, Ravi R Sonani, Datta Madamwar, Paul C Struik, Arjen N Bader, Bruno Robert, Herbert van Amerongen
Cyanobacteria perform photosynthesis with the use of large light-harvesting antennae called phycobilisomes (PBSs). These hemispherical PBSs contain hundreds of open-chain tetrapyrrole chromophores bound to different peptides, providing an arrangement in which excitation energy is funnelled towards the PBS core from where it can be transferred to photosystem I and/or photosystem II. In the PBS core, many allophycocyanin (APC) trimers are present, red-light-absorbing phycobiliproteins that covalently bind phycocyanobilin (PCB) chromophores...
July 28, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28741056/chlorophyll-a-with-a-farnesyl-tail-in-thermophilic-cyanobacteria
#4
Jessica M Wiwczar, Amy M LaFountain, Jimin Wang, Harry A Frank, Gary W Brudvig
Photosystem II (PSII) of oxygenic photosynthetic organisms normally contains exclusively chlorophyll a (Chl a) as its major light-harvesting pigment. Chl a canonically consists of the chlorin headgroup with a 20-carbon, 4-isoprene unit, phytyl tail. We have examined the 1.9 Å crystal structure of PSII from thermophilic cyanobacteria reported by Shen and coworkers in 2012 (PDB accession of 3ARC/3WU2). A newly refined electron density map from this structure, presented here, reveals that some assignments of the cofactors may be different from those modeled in the 3ARC/3WU2 structure, including a specific Chl a that appears to have a truncated tail by one isoprene unit...
July 24, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28741055/effects-of-tunable-excitation-in-carotenoids-explained-by-the-vibrational-energy-relaxation-approach
#5
Vytautas Balevičius, Craig N Lincoln, Daniele Viola, Giulio Cerullo, Jürgen Hauer, Darius Abramavicius
Carotenoids are fundamental building blocks of natural light harvesters with convoluted and ultrafast energy deactivation networks. In order to disentangle such complex relaxation dynamics, several studies focused on transient absorption measurements and their dependence on the pump wavelength. However, such findings are inconclusive and sometimes contradictory. In this study, we compare internal conversion dynamics in [Formula: see text]-carotene, pumped at the first, second, and third vibronic progression peak...
July 24, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28733863/population-level-coordination-of-pigment-response-in-individual-cyanobacterial-cells-under-altered-nitrogen-levels
#6
Jaclyn Murton, Aparna Nagarajan, Amelia Y Nguyen, Michelle Liberton, Harmony A Hancock, Himadri B Pakrasi, Jerilyn A Timlin
Cyanobacterial phycobilisome (PBS) pigment-protein complexes harvest light and transfer the energy to reaction centers. Previous ensemble studies have shown that cyanobacteria respond to changes in nutrient availability by modifying the structure of PBS complexes, but this process has not been visualized for individual pigments at the single-cell level due to spectral overlap. We characterized the response of four key photosynthetic pigments to nitrogen depletion and repletion at the subcellular level in individual, live Synechocystis sp...
July 21, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28721458/a-functional-compartmental-model-of-the-synechocystis-pcc-6803-phycobilisome
#7
Ivo H M van Stokkum, Michal Gwizdala, Lijin Tian, Joris J Snellenburg, Rienk van Grondelle, Herbert van Amerongen, Rudi Berera
In the light-harvesting antenna of the Synechocystis PCC 6803 phycobilisome (PB), the core consists of three cylinders, each composed of four disks, whereas each of the six rods consists of up to three hexamers (Arteni et al., Biochim Biophys Acta 1787(4):272-279, 2009). The rods and core contain phycocyanin and allophycocyanin pigments, respectively. Together these pigments absorb light between 400 and 650 nm. Time-resolved difference absorption spectra from wild-type PB and rod mutants have been measured in different quenching and annihilation conditions...
July 18, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28721457/carbon-use-efficiencies-and-allocation-strategies-in-prochlorococcus-marinus-strain-pcc-9511-during-nitrogen-limited-growth
#8
Kristina Felcmanová, Martin Lukeš, Eva Kotabová, Evelyn Lawrenz, Kimberly H Halsey, Ondřej Prášil
We studied cell properties including carbon allocation dynamics in the globally abundant and important cyanobacterium Prochlorococcus marinus strain PCC 9511 grown at three different growth rates in nitrogen-limited continuous cultures. With increasing nitrogen limitation, cellular divinyl chlorophyll a and the functional absorption cross section of Photosystem II decreased, although maximal photosynthetic efficiency of PSII remained unaltered across all N-limited growth rates. Chl-specific gross and net carbon primary production were also invariant with nutrient-limited growth rate, but only 20% of Chl-specific gross carbon primary production was retained in the biomass across all growth rates...
July 18, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28689227/opposite-domination-of-cyclic-and-pseudocyclic-electron-flows-in-short-illuminated-dark-adapted-leaves-of-angiosperms-and-gymnosperms
#9
Mari Noridomi, Shouta Nakamura, Michito Tsuyama, Norihiro Futamura, Radka Vladkova
The present work was aimed to explain the recently reported higher O2-dependent electron flow capacity in gymnosperms than in angiosperms and to search for other differences in the electron transport processes by simultaneous characterization of the relative capacities of pseudocyclic (direct or Flavodiiron proteins (Flv)-mediated O2-reduction, Mehler(-like) reactions) and cyclic electron flows around photosystem I (CEF-PSI). To this end, a comparative multicomponent analysis was performed on the fluorescence decay curves of dark-adapted leaves after illumination with a 1-s saturating light pulse...
July 8, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28677008/pigment-structure-in-the-violaxanthin-chlorophyll-a-binding-protein-vcp
#10
Manuel J Llansola-Portoles, Radek Litvin, Cristian Ilioaia, Andrew A Pascal, David Bina, Bruno Robert
Resonance Raman spectroscopy was used to evaluate pigment-binding site properties in the violaxanthin-chlorophyll-a-binding protein (VCP) from Nannochloropsis oceanica. The pigments bound to this antenna protein are chlorophyll-a, violaxanthin, and vaucheriaxanthin. The molecular structures of bound Chl-a molecules are discussed with respect to those of the plant antenna proteins LHCII and CP29, the crystal structures of which are known. We show that three populations of carotenoid molecules are bound by VCP, each of which is in an all-trans configuration...
July 4, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28674936/the-fof1-atp-synthase-from-atomistic-three-dimensional-structure-to-the-rotary-chemical-function
#11
REVIEW
Shayantani Mukherjee, Arieh Warshel
Molecular motors are multi-subunit complexes that are indispensable for accomplishing various tasks of the living cells. One such molecular motor is the FOF1 ATP synthase that synthesizes ATP at the expense of the membrane proton gradient. Elucidating the molecular origin of the motor function is challenging despite significant advances in various experimental fields. Currently atomic simulations of whole motor complexes cannot reach to functionally relevant time scales that extend beyond the millisecond regime...
July 3, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28674935/the-paths-of-andrew-a-benson-a-radio-autobiography
#12
Arthur M Nonomura, Barry Holtz, Karl Y Biel, Robert Cooney, George Lorimer, Govindjee
Andrew A. Benson, one of the greatest biochemists of our time, is celebrated on his centennial by the authors with whom he interacted performing experiments or contemplating metabolic pathways in a wide range of biological kingdoms. He charted the chemical flow of energy in cells, tissues, organs, plants, animals, and ecosystems. Benson collaborated with hundreds of colleagues to examine the natural history of autotrophy, mixotrophy, and heterotrophy while elucidating metabolic pathways. We present here a biological perspective of his body of studies...
July 3, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28669083/quenching-of-chlorophyll-triplet-states-by-carotenoids-in-algal-light-harvesting-complexes-related-to-fucoxanthin-chlorophyll-protein
#13
Petro Khoroshyy, David Bína, Zdenko Gardian, Radek Litvín, Jan Alster, Jakub Pšenčík
We have used time-resolved absorption and fluorescence spectroscopy with nanosecond resolution to study triplet energy transfer from chlorophylls to carotenoids in a protective process that prevents the formation of reactive singlet oxygen. The light-harvesting complexes studied were isolated from Chromera velia, belonging to a group Alveolata, and Xanthonema debile and Nannochloropsis oceanica, both from Stramenopiles. All three light-harvesting complexes are related to fucoxanthin-chlorophyll protein, but contain only chlorophyll a and no chlorophyll c...
July 1, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28646418/in-vivo-nmr-as-a-tool-for-probing-molecular-structure-and-dynamics-in-intact-chlamydomonas-reinhardtii-cells
#14
Fatemeh Azadi-Chegeni, Christo Schiphorst, Anjali Pandit
We report the application of NMR dynamic spectral editing for probing the structure and dynamics of molecular constituents in fresh, intact cells and in freshly prepared thylakoid membranes of Chlamydomonas reinhardtii (Cr.) green algae. For isotope labeling, wild-type Cr. cells were grown on (13)C acetate-enriched minimal medium. 1D (13)C J-coupling based and dipolar-based MAS NMR spectra were applied to distinguish (13)C resonances of different molecular components. 1D spectra were recorded over a physiological temperature range, and whole-cell spectra were compared to those taken from thylakoid membranes, evaluating their composition and dynamics...
June 23, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28643169/in-vitro-enzymatic-assays-of-photosynthetic-bacterial-3-vinyl-hydratases-for-bacteriochlorophyll-biosyntheses
#15
Misato Teramura, Jiro Harada, Hitoshi Tamiaki
A chlorosome is a large and efficient light-harvesting antenna system found in some photosynthetic bacteria. This system comprises self-aggregates of bacteriochlorophyll (BChl) c, d, or e possessing a chiral 1-hydroxyethyl group at the 3-position, which plays a key role in the formation of the supramolecule. Biosynthesis of chlorosomal pigments involves stereoselective conversion of 3-vinyl group to 3-(1-hydroxyethyl) group facilitated by a 3-vinyl hydratase. This 3-vinyl hydration also occurs in BChl a biosynthesis, followed by oxidation that introduces an acetyl group at the 3-position...
June 22, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28643168/self-aggregation-of-synthetic-zinc-methyl-20-substituted-3-hydroxymethyl-pyropheophorbides-as-models-of-bacteriochlorophyll-c
#16
Ayaka Wada, Hitoshi Tamiaki
Zinc 3-hydroxymethyl-13(1)-oxo-chlorins bearing a variety of primary alkyl groups at the 20-position were prepared as models of bacteriochlorophyll-c by chemical modification of naturally occurring chlorophyll-a. The synthetic chlorophyll-a derivatives self-aggregated in an aqueous Triton X-100 solution to afford large oligomers whose Soret and Qy bands were red-shifted and broadened, compared with the bands of their monomers in tetrahydrofuran. The oligomeric bands are similar to those of bacteriochlorophyll-c self-aggregates in chlorosomes, the main light-harvesting antennae of photosynthetic green bacteria...
June 22, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28623437/root-derived-bicarbonate-assimilation-in-response-to-variable-water-deficit-in-camptotheca-acuminate-seedlings
#17
Sen Rao, Yanyou Wu
Water deficit is one of the key factors that limits the carbon (C) assimilation and productivity of plants. The effect of variable water deficit on recently root-derived bicarbonate assimilation in Camptotheca acuminate seedlings was investigated. Three-month-old seedlings were subjected to three water regimes, well-watered (WW), moderate stress (MS), and severe stress (SS) induced by polyethyleneglycol, in conjunction with relatively high (H) and low (L) natural (13)C-abundance of NaHCO3-labeled treatments in hydroponics for 14 days...
June 16, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28620699/evolution-of-chlamydomonas-reinhardtii-ferredoxins-and-their-interactions-with-fefe-hydrogenases
#18
REVIEW
Anne Sawyer, Martin Winkler
Ferredoxins are soluble iron sulphur proteins which function as electron donors in a number of metabolic pathways in a broad range of organisms. In photosynthetic organisms, PETF, or ferredoxin 1 (FDX1), is the most studied ferredoxin due to its essential role in photosynthesis, where it transfers electrons from photosystem I to ferredoxin-NADP(+) oxidoreductase. However, PETF can also transfer electrons to a large number of other proteins. One important PETF electron acceptor found in green microalgae is the biologically and biotechnologically important [FeFe]-hydrogenase HYDA, which catalyses the production of molecular hydrogen (H2) from protons and electrons...
June 15, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28593495/association-of-ferredoxin-nadp-oxidoreductase-with-the-photosynthetic-apparatus-modulates-electron-transfer-in-chlamydomonas-reinhardtii
#19
Laura Mosebach, Claudia Heilmann, Risa Mutoh, Philipp Gäbelein, Janina Steinbeck, Thomas Happe, Takahisa Ikegami, Guy Hanke, Genji Kurisu, Michael Hippler
Ferredoxins (FDX) and the FDX:NADP(+) oxidoreductase (FNR) represent a key junction of electron transport downstream of photosystem I (PSI). Dynamic recruitment of FNR to the thylakoid membrane has been considered as a potential mechanism to define the fate of photosynthetically derived electrons. In this study, we investigated the functional importance of the association of FNR with the photosynthetic apparatus in Chlamydomonas reinhardtii. In vitro assays based on NADP(+) photoreduction measurements as well as NMR chemical shift perturbation analyses showed that FNR preferentially interacts with FDX1 compared to FDX2...
June 7, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28577216/concentration-based-self-assembly-of-phycocyanin
#20
Ido Eisenberg, Dvir Harris, Yael Levi-Kalisman, Shira Yochelis, Asaf Shemesh, Gili Ben-Nissan, Michal Sharon, Uri Raviv, Noam Adir, Nir Keren, Yossi Paltiel
Cyanobacteria light-harvesting complexes can change their structure to cope with fluctuating environmental conditions. Studying in vivo structural changes is difficult owing to complexities imposed by the cellular environment. Mimicking this system in vitro is challenging, as well. The in vivo system is highly concentrated, and handling similar in vitro concentrated samples optically is difficult because of high absorption. In this research, we mapped the cyanobacteria antennas self-assembly pathways using highly concentrated solutions of phycocyanin (PC) that mimic the in vivo condition...
June 2, 2017: Photosynthesis Research
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