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Justine Marchand, Parisa Heydarizadeh, Benoît Schoefs, Cornelia Spetea
Chloroplasts are endosymbiotic organelles and play crucial roles in energy supply and metabolism of eukaryotic photosynthetic organisms (algae and land plants). They harbor channels and transporters in the envelope and thylakoid membranes, mediating the exchange of ions and metabolites with the cytosol and the chloroplast stroma and between the different chloroplast subcompartments. In secondarily evolved algae, three or four envelope membranes surround the chloroplast, making more complex the exchange of ions and metabolites...
March 14, 2018: Cellular and Molecular Life Sciences: CMLS
Ashok Aspatwar, Susanna Haapanen, Seppo Parkkila
Carbonic anhydrases (CAs) are metalloenzymes that are omnipresent in nature. CAs catalyze the basic reaction of the reversible hydration of CO₂ to HCO₃- and H⁺ in all living organisms. Photosynthetic organisms contain six evolutionarily different classes of CAs, which are namely: α-CAs, β-CAs, γ-CAs, δ-CAs, ζ-CAs, and θ-CAs. Many of the photosynthetic organisms contain multiple isoforms of each CA family. The model alga Chlamydomonas reinhardtii contains 15 CAs belonging to three different CA gene families...
March 13, 2018: Metabolites
Zhen Yu, Rui Hao, Liang Zhang, Yi Zhu
Nanoparticles (NPs) are inevitably released into the aquatic environment for being widely used and may affect the toxicity of other contaminants already present in the environment, such as trace metals. However, the effects of NPs on the ecotoxicity of cadmium (Cd), a common environmental trace metal pollutant, are not well explored. In this study, effects of four widely used NPs TiO2 (n-TiO2 ), SiO2 (n-SiO2 ), Ag (n-Ag) and CdTe/CdS core/shell quantum dots (QD) on the toxicity of Cd to the freshwater algae Chlamydomonas reinhardtii were assessed respectively...
March 13, 2018: Ecotoxicology and Environmental Safety
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
Sigrun Rumpel, Constanze Sommer, Edward Reijerse, Christophe Farès, Wolfgang Lubitz
Hydride state intermediates are known to occur in various hydrogen conversion enzymes, including the highly efficient [FeFe] hydrogenases. The intermediate state involving a terminal iron-bound hydride has been recognized as crucial for the catalytic mechanism, but its occurrence has up to now eluded unequivocal proof under (near) physiological conditions. Here we show that the terminal hydride in the [FeFe] hydrogenase from Chlamydomonas reinhardtii can be directly detected using solution 1H NMR spectroscopy at room temperature, opening new avenues for detailed in-situ investigations under catalytic conditions...
March 9, 2018: Journal of the American Chemical Society
Huawen Lin, Zhengyan Zhang, Carlo Iomini, Susan K Dutcher
Intraflagellar transport moves proteins in and out of flagella/cilia and it is essential for the assembly of these organelles. Using whole-genome sequencing, we identified splice site mutations in two IFT genes, IFT81 ( fla9 ) and IFT121 ( ift121-2 ), which lead to flagellar assembly defects in the unicellular green alga Chlamydomonas reinhardtii The splicing defects in these ift mutants are partially corrected by mutations in two conserved spliceosome proteins, DGR14 and FRA10. We identified a dgr14 deletion mutant, which suppresses the 3' splice site mutation in IFT81 , and a frameshift mutant of FRA10 , which suppresses the 5' splice site mutation in IFT121 Surprisingly, we found dgr14-1 and fra10 mutations suppress both splice site mutations...
March 2018: Open Biology
Helene Launay, Patrick Barre, Carine Puppo, Yizhi Zhang, Stéphanie Manneville, Brigitte Gontero, Véronique Receveur-Brechot
Among intrinsically disordered proteins, conditionally disordered proteins undergo dramatic structural disorder rearrangements upon environmental changes and/or post-translational modifications that directly modulate their function. Quantifying the dynamics of these fluctuating proteins is extremely challenging but paramount to understanding the regulation of their function. The chloroplast protein CP12 is a model of such proteins, and acts as a redox switch by formation/disruption of its two disulfide bridges...
February 28, 2018: Journal of Molecular Biology
Sakina Bensalem, Filipa Lopes, Pierre Bodénès, Dominique Pareau, Olivier Français, Bruno Le Pioufle
One way envisioned to overcome part of the issues biodiesel production encounters today is to develop a simple, economically viable and eco-friendly process for the extraction of lipids from microalgae. This study investigates the lipid extraction efficiency from the microalga Chlamydomonas reinhardtii as well as the underlying mechanisms. We propose a new methodology combining a pulsed electric field (PEF) application and mechanical stresses as a pretreatment to improve lipid extraction with solvents. Cells enriched in lipids are therefore submitted to electric field pulses creating pores on the cell membrane and then subjected to a mechanical stress by applying cyclic pressures on the cell wall (using a microfluidic device)...
February 10, 2018: Bioresource Technology
Yu Zhan, Christophe H Marchand, Alexandre Maes, Adeline Mauries, Yi Sun, James S Dhaliwal, James Uniacke, Simon Arragain, Heng Jiang, Nicholas D Gold, Vincent J J Martin, Stéphane D Lemaire, William Zerges
Organelles are intracellular compartments which are themselves compartmentalized. Biogenic and metabolic processes are localized to specialized domains or microcompartments to enhance their efficiency and suppress deleterious side reactions. An example of intra-organellar compartmentalization is the pyrenoid in the chloroplasts of algae and hornworts. This microcompartment enhances the photosynthetic CO2-fixing activity of the Calvin-Benson cycle enzyme Rubisco, suppresses an energetically wasteful oxygenase activity of Rubisco, and mitigates limiting CO2 availability in aquatic environments...
2018: PloS One
Valéria Nagy, André Vidal-Meireles, Anna Podmaniczki, Klára Szentmihályi, Gábor Rákhely, Laura Zsigmond, László Kovács, Szilvia Z Tóth
Sulphur limitation may restrain cell growth and viability. In the green alga, Chlamydomonas reinhardtii, sulphur limitation may induce H2 production lasting for several days, to be exploited as a renewable energy source. Sulphur limitation causes a large number of physiological changes, including the inactivation of photosystem II (PSII), leading to the establishment of hypoxia, essential for the increase in hydrogenase expression and activity. The inactivation of PSII has been long assumed to be caused by the sulphur-limited turnover of its reaction center protein, PsbA...
February 23, 2018: Plant Journal: for Cell and Molecular Biology
Emily L Hunter, Karl Lechtreck, Gang Fu, Juyeon Hwang, Huawen Lin, Avanti Gokhale, Lea M Alford, Brian Lewis, Ryosuke Yamamoto, Ritsu Kamiya, Fan Yang, Daniela Nicastro, Susan K Dutcher, Maureen Wirschell, Winfield S Sale
Axonemal dyneins, including inner dynein arm I1, assemble in the cytoplasm prior to transport into cilia by intraflagellar transport (IFT). How I1 dynein interacts with IFT is not understood. We take advantage of the Chlamydomonas reinhardtii ida3 mutant that assembles the inner arm I1 dynein complex in the cytoplasm but fails to transport I1 into the cilium, resulting in I1 dynein-deficient axonemes with abnormal motility. The IDA3 gene encodes a ∼115 kDa coiled-coil protein that primarily enters the cilium during ciliary growth but is not an axonemal protein...
February 21, 2018: Molecular Biology of the Cell
Serena Lima, Conner L Webb, Evelyne Deery, Colin Robinson, Julie A Z Zedler
Dietary supplements and functional foods are becoming increasingly popular complements to regular diets. A recurring ingredient is the essential cofactor vitamin B12 (B12 ). Microalgae are making their way into the dietary supplement and functional food market but do not produce B12 , and their B12 content is very variable. In this study, the suitability of using the human B12 -binding protein intrinsic factor (IF) to enrich bioavailable B12 using microalgae was tested. The IF protein was successfully expressed from the nuclear genome of the model microalga C hlamydomonas reinhardtii and the addition of an N-terminal ARS2 signal peptide resulted in efficient IF secretion to the medium...
February 19, 2018: Biology
Ayswarya Ravi, Shengchun Guo, Beth Rasala, Miller Tran, Stephen Mayfield, Zivko L Nikolov
Correct folding and post-translational modifications are vital for therapeutic proteins to elicit their biological functions. Osteopontin (OPN), a bone regenerative protein present in a range of mammalian cells, is an acidic phosphoprotein with multiple potential phosphorylation sites. In this study, the ability of unicellular microalgae, Chlamydomonas reinhardtii , to produce phosphorylated recombinant OPN in its chloroplast is investigated. This study further explores the impact of phosphorylation and expression from a "plant-like" algae on separation of OPN...
February 16, 2018: International Journal of Molecular Sciences
Lei Yang, Jun Chen, Shan Qin, Min Zeng, Yongguang Jiang, Lang Hu, Peng Xiao, Wenlong Hao, Zhangli Hu, Anping Lei, Jiangxin Wang
Background: Individual nutrient depletion is widely used to induce lipid accumulation in microalgae, which also causes cell growth inhibition and decreases the total biomass. Thus, improving the lipid accumulation without biomass loss in the nutrient deficiency cells becomes a potential cost-effective treatment for cheaper biofuels. Methods: In this study, the effects of different nutritional conditions on the growth and contents of lipids in Chlamydomonas reinhardtii were compared, and the metabolic profiles under different nutritional conditions were also investigated...
2018: Biotechnology for Biofuels
Paola Mini, Olivia Costantina Demurtas, Silvia Valentini, Patrizia Pallara, Giuseppe Aprea, Paola Ferrante, Giovanni Giuliano
BACKGROUND: Chlamydomonas reinhardtii is an unicellular green alga used for functional genomics studies and heterologous protein expression. A major hindrance in these studies is the low level and instability of expression of nuclear transgenes, due to their rearrangement and/or silencing over time. RESULTS: We constructed dedicated vectors for Agrobacterium-mediated transformation carrying, within the T-DNA borders, the Paromomycin (Paro) selectable marker and an expression cassette containing the Luciferase (Luc) reporter gene...
February 17, 2018: BMC Biotechnology
Hui Li, Yanmei Liu, Yuting Wang, Meirong Chen, Xiaoshan Zhuang, Chaogang Wang, Jiangxin Wang, Zhangli Hu
Background: Sulfur-deprived cultivation of Chlamydomonas reinhardtii , referred as "two-stage culture" transferring the cells from regular algal medium to sulfur-deplete one, has been extensively studied to improve photobio-H 2 production in this green microalga. During sulfur-deprivation treatment, the synthesis of a key component of photosystem II complex, D1 protein, was inhibited and improved photobio-H 2 production could be established in C. reinhardtii . However, separation of algal cells from a regular liquid culture medium to a sulfur-deprived one is not only a discontinuous process, but also a cost- and time-consuming operation...
2018: Biotechnology for Biofuels
Zhi-Yan Du, Ben Franklin Lucker, Krzysztof Zienkiewicz, Tarryn E Miller, Agnieszka Zienkiewicz, Barbara B Sears, David M Kramer, Christoph Benning
Photosynthesis occurs in the thylakoid membrane, where the predominant lipid is monogalactosyldiacylglycerol (MGDG). As environmental conditions change, photosynthetic membranes have to adjust. In this study, we used a loss-of-function Chlamydomonas reinhardtii mutant deficient in the MGDG-specific lipase PGD1 (PLASTID GALACTOGLYCEROLIPID DEGRADATION1) to investigate the link between MGDG turnover, chloroplast ultrastructure, and the production of reactive oxygen species (ROS) in response to different adverse environmental conditions...
February 5, 2018: Plant Cell
Xiao Tan, Danfeng Zhang, Keshab Parajuli, Sanjina Upadhyay, Yuji Jiang, Zhipeng Duan
Ultrasound has been regarded as an environmental friendly technology to utilize microalgae biomass and control algal blooms. In this study, four quantitative techniques, including cell counting, optical density of algal suspension, pigments release, and protein release, were performed on three species of microalgae (M. aeruginosa, C. pyrenoidosa, and C. reinhardtii) to develop effective techniques for rapid monitoring of cell disruption and to optimize the acoustic energy efficiency. Results showed optical density of algal suspensions was not an optimal indicator to monitor cell disruption, although it is a common technique for determining cell concentration in microbial cultures...
February 12, 2018: Environmental Science & Technology
Lena A Kosak Née Röhder, Tanja Brandt, Laura Sigg, Renata Behra
Cerium (Ce) and cerium oxide nanoparticles (CeO2 NP) are increasingly used in different applications. Upon their release into the aquatic environment, the exposure of aquatic organisms becomes likely. In this study, the uptake of CeO2 NP and Ce3+ into the wild type and cell wall free mutant of Chlamydomonas reinhardtii was examined upon short term exposure. Separation of CeO2 NP and Ce3+ not taken up or loosely bound to the cells was performed by washing algae with EDTA. Despite a concentration and time dependent increase of cellular Ce upon exposure to CeO2 NP with the maximal calculated Ce concentration corresponding to 1...
February 7, 2018: Aquatic Toxicology
Basilius Thalmann, Urs von Gunten, Ralf Kaegi
Ozonation can be applied to mitigate the discharge of organic micropollutants from municipal wastewater treatment plants (WWTPs) to the aquatic environment. The toxicity of metals also present in WWTP effluents strongly depends on their speciation. Therefore, knowledge on the change of the metal speciation during ozonation of a WWTP effluent is essential to assess possible negative impacts. The kinetics and the stoichiometries of the reactions of ozone with three metal sulfides (ZnS, CuS and CdS) and metal-ethylenediaminetetraacetate (EDTA)/nitriloriacetic acid (NTA) complexes of Cu(II), Cd(II), Ni(II), Zn(II), Mg(II) and Pb(II) were investigated...
February 6, 2018: Water Research
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