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Photosynthesis Research

Trevor S Kashey, Dustin D Luu, John C Cowgill, Patricia L Baker, Kevin E Redding
Photosynthetic reaction centers (RCs) evolved > 3 billion years ago and have diverged into Type II RCs reducing quinones and Type I RCs reducing soluble acceptors via iron-sulfur clusters. Photosystem I (PSI), the exemplar Type I RC, uses modified menaquinones as intermediate electron transfer cofactors, but it has been controversial if the Type I RC of heliobacteria (HbRC) uses its two bound menaquinones in the same way. The sequence of the quinone-binding site in PSI is not conserved in the HbRC, and the recently solved crystal structure of the HbRC does not reveal a quinone in the analogous site...
March 12, 2018: Photosynthesis Research
María Jesús García-Murria, Hemanth P K Sudhani, Julia Marín-Navarro, Manuel M Sánchez Del Pino, Joaquín Moreno
Oxidation of the cysteines from ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) leads to inactivation and promotes structural changes that increase the proteolytic sensitivity and membrane association propensity related to its catabolism. To uncover the individual role of the different cysteines, the sequential order of modification under increasing oxidative conditions was determined using chemical labeling and mass spectrometry. Besides, site-directed RubisCO mutants were obtained in Chlamydomonas reinhardtii replacing single conserved cysteines (Cys84, Cys172, Cys192, Cys247, Cys284, Cys427, Cys459 from the large and sCys41, sCys83 from the small subunit) and the redox properties of the mutant enzymes were determined...
March 10, 2018: Photosynthesis Research
D Jun, H S Dhupar, A Mahmoudzadeh, F Duong, J D W Madden, J T Beatty
We address a challenge in the engineering of proteins to redirect electron transfer pathways, using the bacterial photosynthetic reaction centre (RC) pigment-protein complex. Direct electron transfer is shown to occur from the QA quinone of the Rhodobacter sphaeroides RC containing a truncated H protein and bound on the quinone side to a gold electrode. In previous reports of binding to the quinone side of the RC, electron transfer has relied on the use of a soluble mediator between the RC and an electrode, in part because the probability of QB quinone reduction is much greater than that of direct electron transfer through the large cytoplasmic domain of the H subunit, presenting a ~ 25 Å barrier...
March 9, 2018: Photosynthesis Research
Ginga Shimakawa, Chikahiro Miyake
Oxygenic phototrophs are vulnerable to damage by reactive oxygen species (ROS) that are produced in photosystem I (PSI) by excess photon energy over the demand of photosynthetic CO2 assimilation. In plant leaves, repetitive short-pulse (rSP) illumination produces ROS to inactivate PSI. The production of ROS is alleviated by oxidation of the reaction center chlorophyll in PSI, P700, during the illumination with the short-pulse light, which is supported by flavodiiron protein (FLV). In this study, we found that in the cyanobacterium Synechocystis sp...
March 8, 2018: Photosynthesis Research
Vasily V Ptushenko, Tatiana V Zhigalova, Olga V Avercheva, Alexander N Tikhonov
In plants, the short-term regulation (STR, seconds to minute time scale) of photosynthetic apparatus is associated with the energy-dependent control in the chloroplast electron transport, the distribution of light energy between photosystems (PS) II and I, activation/deactivation of the Calvin-Benson cycle (CBC) enzymes, and relocation of chloroplasts within the plant cell. In this work, using a dual-PAM technique for measuring the time-courses of P700 photooxidation and Chl a fluorescence, we have investigated the STR events in Tradescantia fluminensis leaves...
March 7, 2018: Photosynthesis Research
Michele Nottoli, Sandro Jurinovich, Lorenzo Cupellini, Alastair T Gardiner, Richard Cogdell, Benedetta Mennucci
The LH2 antenna complexes of purple bacteria occur, depending on light conditions, in various different spectroscopic forms, with a similar structure but different absorption spectra. The differences are related to point changes in the primary amino acid sequence, but the molecular-level relationship between these changes and the resulting spectrum is still not well understood. We undertook a systematic quantum chemical analysis of all the main factors that contribute to the exciton structure, looking at how the environment modulates site energies and couplings in the B800-850 and B800-820 spectroscopic forms of LH2...
March 3, 2018: Photosynthesis Research
Shardendu K Singh, Vangimalla R Reddy
Plants photosynthesis-related traits are co-regulated to capture light and CO2 to optimize the rate of CO2 assimilation (A). The rising CO2 often benefits, but potassium (K) deficiency adversely affects A that contributes to the majority of plant biomass. To evaluate mechanisms of photosynthetic limitations and adaptations, soybean was grown under controlled conditions with an adequate (control, 5.0 mM) and two K-deficient (moderate, 0.50 and severe, 0.02 mM) levels under ambient (aCO2 ; 400 µmol mol-1 ) and elevated CO2 (eCO2 ; 800 µmol mol-1 )...
February 24, 2018: Photosynthesis Research
Jérôme Morelle, Pascal Claquin
Diatoms account for about 40% of primary production in highly productive ecosystems. The development of a new generation of fluorometers has made it possible to improve estimation of the electron transport rate from photosystem II, which, when coupled with the carbon incorporation rate enables estimation of the electrons required for carbon fixation. The aim of this study was to investigate the daily dynamics of these electron requirements as a function of the diel light cycle in three relevant diatom species and to apprehend if the method of estimating the electron transport rate can lead to different pictures of the dynamics...
February 23, 2018: Photosynthesis Research
Robert E Blankenship, Daniel C Brune, Jon C Olson
Here we provide reflections of and a tribute to John M. Olson, a pioneering researcher in photosynthesis. We trace his career, which began at Wesleyan University and the University of Pennsylvania, and continued at Utrech in The Netherlands, Brookhaven National Laboratory, and Odense University in Denmark. He was the world expert on pigment organization in the green photosynthetic bacteria, and discovered and characterized the first chlorophyll-containing protein, which has come to be known as the Fenna-Matthews-Olson (FMO) protein...
February 19, 2018: Photosynthesis Research
Jean-David Rochaix, Chanhong Kim, Wiebke Apel
We present here a Tribute to Klaus Apel (1942-2017), a photosynthesis pioneer-an authority on plant molecular genetics-in five parts. The first section is a prologue. The second section deals with a chronological discussion of Apel's research life, prepared by the editor Govindjee; it is based on a website article at the Boyce Thompson Institute (BTI) by Patricia Waldron ( ), as approved for use here by Keith C. Hannon and David Stern of BTI...
February 16, 2018: Photosynthesis Research
Eliezer M Schwarz, Stephanie Tietz, John E Froehlich
The funding statement in the last sentence of the Acknowledgements section in the original publication is incorrect. The corrected Acknowledgements section is printed below.
February 5, 2018: Photosynthesis Research
Fei Chen, Guojun Dong, Xiaohui Ma, Fang Wang, Yanli Zhang, Erhui Xiong, Jiahuan Wu, Huizhong Wang, Qian Qian, Limin Wu, Yanchun Yu
Isolation of leaf-color mutants is important in understanding the mechanisms of chloroplast biogenesis and development. In this study, we identified and characterized a rice (Oryza sativa) mutant, yellow leaf 2 (yl2), exhibiting pale yellow leaves with a few longitudinal white stripes at the early seedling stage then gradually turning yellow. Genetic analyses revealed that YL2 encodes a thylakoid membrane-localized protein with significant sequence similarity to UMP kinase proteins in prokaryotes and eukaryotes...
February 1, 2018: Photosynthesis Research
Marian Brestic, Marek Zivcak, Pavol Hauptvogel, Svetlana Misheva, Konstantina Kocheva, Xinghong Yang, Xiangnan Li, Suleyman I Allakhverdiev
Assessment of photosynthetic traits and temperature tolerance was performed on field-grown modern genotype (MG), and the local landrace (LR) of wheat (Triticum aestivum L.) as well as the wild relative species (Aegilops cylindrica Host.). The comparison was based on measurements of the gas exchange (A/ci, light and temperature response curves), slow and fast chlorophyll fluorescence kinetics, and some growth and leaf parameters. In MG, we observed the highest CO2 assimilation rate [Formula: see text] electron transport rate (Jmax) and maximum carboxylation rate [Formula: see text]...
January 30, 2018: Photosynthesis Research
Stephen K Herbert, Yona Siderer, Govindjee
We present here the life and work of Shmuel Malkin (1934-2017), an accomplished scientist and a gifted musician who touched the lives of many around the world. His early scientific work addressed the dynamics of light harvesting and electron transport in photosynthesis. Later, he used photoacoustic and photothermal methodologies to explore all aspects of photosynthesis. As a musician, Shmuel played the piano often for family and friends but after his formal retirement, he produced a body of original musical compositions, many of which were performed publicly...
January 30, 2018: Photosynthesis Research
Ryan M Taylor, Larry Sallans, Laurie K Frankel, Terry M Bricker
The cytochrome b 6 f complex of oxygenic photosynthesis produces substantial levels of reactive oxygen species (ROS). It has been observed that the ROS production rate by b 6 f is 10-20 fold higher than that observed for the analogous respiratory cytochrome bc1 complex. The types of ROS produced (O2•-, 1O2, and, possibly, H2O2) and the site(s) of ROS production within the b 6 f complex have been the subject of some debate. Proposed sources of ROS have included the heme b p , PQ p•- (possible sources for O2•-), the Rieske iron-sulfur cluster (possible source of O2•- and/or 1O2), Chl a (possible source of 1O2), and heme c n (possible source of O2•- and/or H2O2)...
January 29, 2018: Photosynthesis Research
Erhard E Pfündel, Gwendal Latouche, Armin Meister, Zoran G Cerovic
Low light (LL) and high light (HL)-acclimated plants of A. thaliana were exposed to blue (BB) or red (RR) light or to a mixture of blue and red light (BR) of incrementally increasing intensities. The light response of photosystem II was measured by pulse amplitude-modulated chlorophyll fluorescence and that of photosystem I by near infrared difference spectroscopy. The LL but not HL leaves exhibited blue light-specific responses which were assigned to relocation of chloroplasts from the dark to the light-avoidance arrangement...
January 27, 2018: Photosynthesis Research
Karl-Josef Dietz, G Heinrich Krause, Katharina Siebke, Anja Krieger-Liszkay
The dynamic and efficient coordination of primary photosynthetic reactions with leaf energization and metabolism under a wide range of environmental conditions is a fundamental property of plants involving processes at all functional levels. The present historical perspective covers 60 years of research aiming to understand the underlying mechanisms, linking major breakthroughs to current progress. It centers on the contributions of Ulrich Heber who had pioneered novel concepts, fundamental methods, and mechanistic understanding of photosynthesis...
January 24, 2018: Photosynthesis Research
Wei Huang, Mikko Tikkanen, Shi-Bao Zhang
We studied how high light causes photoinhibition of photosystem I (PSI) in the shade-demanding fern Nephrolepis falciformis, in an attempt to understand the mechanism of PSI photoinhibition under natural field conditions. Intact leaves were treated with constant high light and fluctuating light. Detached leaves were treated with constant high light in the presence and absence of methyl viologen (MV). Chlorophyll fluorescence and P700 signal were determined to estimate photoinhibition. PSI was highly oxidized under high light before treatments...
January 22, 2018: Photosynthesis Research
A H Jay Burr, Aaron Vidaver, Ulrich Schreiber, Doug Bruce, Danielle J Donnelly
William (Bill) E. Vidaver (February 2, 1921-August 31, 2017), who did his Ph.D. with Laurence (Larry) R. Blinks at Stanford (1964) and a postdoc with C. Stacy French (1965), taught and did research at Simon Fraser University (SFU) for almost 30 years. Here he published over 80 papers in photosynthesis-related areas co-authored by his graduate students, postdocs, visiting professors and SFU colleagues. He developed a unique high-pressure cuvette for the study of oxygen exchange and studied high-pressure effects in photosynthesis...
January 19, 2018: Photosynthesis Research
Hiroki Makita, Gary Hastings
Time-resolved FTIR difference spectroscopy has been used to study photosystem I (PSI) particles with three different benzoquinones [plastoquinone-9 (PQ), 2,6-dimethyl-1,4-benzoquinone (DMBQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (Cl4BQ)] incorporated into the A1 binding site. If PSI samples are cooled in the dark to 77 K, the incorporated benzoquinones are shown to be functional, allowing the production of time-resolved (P700+A1--P700A1) FTIR difference spectra. If samples are subjected to repetitive flash illumination at room temperature prior to cooling, however, the time-resolved FTIR difference spectra at 77 K display contributions typical of the P700 triplet state (3P700), indicating a loss of functionality of the incorporated benzoquinones, that occurs because of double protonation of the incorporated benzoquinones...
January 13, 2018: Photosynthesis Research
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