The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Erin K Oshea - One of the best experts on this subject based on the ideXlab platform.
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dynamical localization of a thylakoid membrane binding protein is required for acquisition of photosynthetic competency
Molecular Microbiology, 2018Co-Authors: Andrian Gutu, Frederick S Chang, Erin K OsheaAbstract:Vipp1 is highly conserved and essential for photosynthesis, but its function is unclear as it does not participate directly in Light-Dependent Reactions. We analyzed Vipp1 localization in live cyanobacterial cells and show that Vipp1 is highly dynamic, continuously exchanging between a diffuse fraction that is uniformly distributed throughout the cell and a punctate fraction that is concentrated at high curvature regions of the thylakoid located at the cell periphery. Experimentally perturbing the spatial distribution of Vipp1 by relocalizing it to the nucleoid causes a severe growth defect during the transition from non-photosynthetic (dark) to photosynthetic (light) growth. However, the same perturbation of Vipp1 in dark alone or light alone growth conditions causes no growth or thylakoid morphology defects. We propose that the punctuated dynamics of Vipp1 at the cell periphery in regions of high thylakoid curvature enable acquisition of photosynthetic competency, perhaps by facilitating biogenesis of photosynthetic complexes involved in Light-Dependent Reactions of photosynthesis.
Cornelia Spetea - One of the best experts on this subject based on the ideXlab platform.
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Function and evolution of channels and transporters in photosynthetic membranes
Cellular and Molecular Life Sciences, 2014Co-Authors: Bernard E. Pfeil, Benoît Schoefs, Cornelia SpeteaAbstract:Chloroplasts from land plants and algae originated from an endosymbiotic event, most likely involving an ancestral photoautotrophic prokaryote related to cyanobacteria. Both chloroplasts and cyanobacteria have thylakoid membranes, harboring pigment-protein complexes that perform the Light-Dependent Reactions of oxygenic photosynthesis. The composition, function and regulation of these complexes have thus far been the major topics in thylakoid membrane research. For many decades, we have also accumulated biochemical and electrophysiological evidence for the existence of solute transthylakoid transport activities that affect photosynthesis. However, research dedicated to molecular identification of the responsible proteins has only recently emerged with the explosion of genomic information. Here we review the current knowledge about channels and transporters from the thylakoid membrane of Arabidopsis thaliana and of the cyanobacterium Synechocystis sp. PCC 6803. No homologues of these proteins have been characterized in algae, although similar sequences could be recognized in many of the available sequenced genomes. Based on phylogenetic analyses, we hypothesize a host origin for most of the so far identified Arabidopsis thylakoid channels and transporters. Additionally, the shift from a non-thylakoid to a thylakoid location appears to have occurred at different times for different transport proteins. We propose that closer control of and provision for the thylakoid by products of the host genome has been an ongoing process, rather than a one-step event. Some of the proteins recruited to serve in the thylakoid may have been the result of the increased specialization of its pigment-protein composition and organization in green plants.
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Role of Chloroplast Thylakoid Lumen in Photosynthetic Regulation and Plant Cell Signaling
Progress in Botany, 2011Co-Authors: Cornelia SpeteaAbstract:The aqueous lumen enclosed by the thylakoid membrane network of the chloroplast is the compartment where molecular oxygen is produced from water during photosynthetic Light-Dependent Reactions. The thylakoid lumen has been thought for a long time to contain mainly plastocyanin and oxygen-evolving complex-associated proteins, playing important roles during these Reactions. In the last decade, the functional characterization of thylakoid lumenal proteins from Arabidopsis thaliana has brought insights into the complex role of this subcellular compartment. The aim of this chapter is to provide an updated view of the protein composition of the thylakoid lumen and its emerging roles in photosynthetic regulation and plant cell signaling. Recent research has uncovered redox signaling and a new paradigm about the role of nucleotides in the thylakoid lumen.
Maria Celeste Dias - One of the best experts on this subject based on the ideXlab platform.
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Photosynthesis light-independent Reactions are sensitive biomarkers to monitor lead phytotoxicity in a Pb-tolerant Pisum sativum cultivar
Environmental science and pollution research international, 2014Co-Authors: Eleazar Rodriguez, Maria Da Conceição Santos, Raquel Azevedo, Carlos Correia, José Moutinho-pereira, José Miguel P. Ferreira De Oliveira, Maria Celeste DiasAbstract:Lead (Pb) environmental contamination remains prevalent. Pisum sativum L. plants have been used in ecotoxicological studies, but some cultivars showed to tolerate and accumulate some levels of Pb, opening new perspectives to their use in phytoremediation approaches. However, the putative use of pea plants in phytoremediation requires reliable toxicity endpoints. Here, we evaluated the sensitivity of a large number of photosynthesis-related biomarkers in Pb-exposed pea plants. Plants (cv. “Corne de Belier”) were exposed to Pb concentrations up to 1,000 mg kg−1 soil during 28 days. The photosynthetic potential biomarkers that were analyzed included pigments, chlorophyll (Chl) a fluorescence, gas exchange, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) activity, and carbohydrates. Flow cytometry (FCM) was also used to assess the morpho-functional status of chloroplasts. Finally, Pb-induced nutrient disorders were also evaluated. Net CO2 assimilation rate (A) and RuBisCO activity decreased strongly in Pb-exposed plants. Plant dry mass (DM) accumulation, however, was only reduced in the higher Pb concentrations tested (500 and 1,000 mg kg−1 soil). Pigment contents increased solely in plants exposed to the largest Pb concentration, and in addition, the parameters related to the Light-Dependent Reactions of photosynthesis, F v/F m and ΦPSII, were not affected by Pb exposure. In contrast to this, carbohydrates showed an overall tendency to increase in Pb-exposed plants. The morphological status of chloroplasts was affected by Pb exposure, with a general trend of volume decrease and granularity increase. These results point the endpoints related to the light-independent Reactions of photosynthesis as more sensitive predictors of Pb-toxicity than the Light-Dependent Reactions ones. Among the endpoints related to the light-independent photosynthesis Reactions, RuBisCO activity and A were found to be the most sensitive. We discuss here the advantages of using these parameters as biomarkers for Pb toxicity in plants. Finally, we report that, despite showing physiological disorders, these cultivar plants survived and accumulated high doses of Pb, and their use in environmental/decontamination studies is open to debate.
Shunichi Fukuzumi - One of the best experts on this subject based on the ideXlab platform.
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Solar energy conversion: From natural to artificial photosynthesis
Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 2017Co-Authors: Mohamed E. El-khouly, Eithar El-mohsnawy, Shunichi FukuzumiAbstract:Solar energy has a great potential as a clean, cheap, renewable and sustainable energy source, but it must be captured and transformed into useful forms of energy as plants do. An especially attractive approach is to store solar energy in the form of chemical bonds as performed in natural photosynthesis. Therefore, there is a challenge in the last decades to construct semi-artificial and artificial photosynthetic systems, which are able to efficiently capture and convert solar energy and then store it in the form of chemical bonds of solar fuels such as hydrogen or hydrogen peroxide, while at the time producing oxygen from water. Here, we review the molecular level details of the natural photosynthesis, particularly the mechanism of light dependent Reactions in oxygen evolving organisms, absorption efficiency of solar energy and direct energy production. We then demonstrate the concept and examples of the semi-artificial photosynthesis in vitro. Finally we demonstrate the artificial photosynthesis, which is composed of light harvesting and charge-separation units together with catalytic units of water oxidation and reduction as well as CO2 reduction. The reported photosynthetic molecular and supramolecular systems have been designed and examined in order to mimic functions of the antenna-reaction center of the natural process. The relations between structures and photochemical behaviors of these artificial photosynthetic systems are discussed in relation to the rates and efficiencies of charge-separation and charge-recombination processes by utilizing the laser flash photolysis technique, as well as other complementary techniques. Finally the photocatalytic production of hydrogen peroxide as a more promising solar fuel is discussed in relation with the natural photosynthesis, which also produces hydrogen peroxide in addition to NADPH.
Andrian Gutu - One of the best experts on this subject based on the ideXlab platform.
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dynamical localization of a thylakoid membrane binding protein is required for acquisition of photosynthetic competency
Molecular Microbiology, 2018Co-Authors: Andrian Gutu, Frederick S Chang, Erin K OsheaAbstract:Vipp1 is highly conserved and essential for photosynthesis, but its function is unclear as it does not participate directly in Light-Dependent Reactions. We analyzed Vipp1 localization in live cyanobacterial cells and show that Vipp1 is highly dynamic, continuously exchanging between a diffuse fraction that is uniformly distributed throughout the cell and a punctate fraction that is concentrated at high curvature regions of the thylakoid located at the cell periphery. Experimentally perturbing the spatial distribution of Vipp1 by relocalizing it to the nucleoid causes a severe growth defect during the transition from non-photosynthetic (dark) to photosynthetic (light) growth. However, the same perturbation of Vipp1 in dark alone or light alone growth conditions causes no growth or thylakoid morphology defects. We propose that the punctuated dynamics of Vipp1 at the cell periphery in regions of high thylakoid curvature enable acquisition of photosynthetic competency, perhaps by facilitating biogenesis of photosynthetic complexes involved in Light-Dependent Reactions of photosynthesis.