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Sato N, Sato M, Wakazaki M, Moriyama T, Hirashima T, Toyooka K. Chloroplasts with clefts and holes: a reassessment of the chloroplast shape using 3D FE-SEM cellular reconstruction of two species of Chlamydomonas. PROTOPLASMA 2024:10.1007/s00709-024-01990-7. [PMID: 39320475 DOI: 10.1007/s00709-024-01990-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2024] [Accepted: 09/05/2024] [Indexed: 09/26/2024]
Abstract
Chloroplasts are usually considered spheroid organelles, but this is not the only shape of chloroplasts. The chloroplast of Chlamydomonas has been typically described as cup-shaped. However, in old studies, it was also modeled as a complex shape with "perforations" or windows. Here, we reconstructed the cellular architecture of Chlamydomonas reinhardtii and C. applanata using an array tomography system installed on a field emission scanning electron microscope. C. reinhardtii chloroplasts resembled a baseball glove or a cup without a side, featuring numerous large and small holes that may facilitate the transport of metabolites and proteins produced in the Golgi apparatus fitted in the holes. In a lipid-accumulating, high-light condition, the chloroplast volume increased by filling the side cleft with an entire wall. Many accumulated large lipid droplets were accommodated within the chloroplast holes, which could have been considered as "chloroplast lipid droplets." Mitochondrial meshworks surrounded the chloroplast. C. applanata chloroplasts appeared like a folded starfish or a cup with many side clefts and a few holes. There was a single mitochondrion or two that branched in a complex form. Tight contacts of various organelles were also found in C. applanata. These reconstructions illustrate the complexity of chloroplast shape, which necessitates a revised understanding of the localization of lipid droplets and the evolution of chloroplasts: The prevailing image of the spheroid chloroplasts that reminds us of the similarity between chloroplasts and cyanobacteria is no longer tenable.
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Affiliation(s)
- Naoki Sato
- Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-Ku, Tokyo, 153-8902, Japan.
| | - Mayuko Sato
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan
| | - Mayumi Wakazaki
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan
| | - Takashi Moriyama
- Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-Ku, Tokyo, 153-8902, Japan
- Kyoto Research Laboratory, Beacle Inc, Kyoto, 606-8305, Japan
| | - Takashi Hirashima
- Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-Ku, Tokyo, 153-8902, Japan
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, 603-8555, Japan
| | - Kiminori Toyooka
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan
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Ďúranová H, Šimora V, Ďurišová Ľ, Olexiková L, Kovár M, Požgajová M. Modifications in Ultrastructural Characteristics and Redox Status of Plants under Environmental Stress: A Review. PLANTS (BASEL, SWITZERLAND) 2023; 12:1666. [PMID: 37111889 PMCID: PMC10144148 DOI: 10.3390/plants12081666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 03/30/2023] [Accepted: 04/05/2023] [Indexed: 06/19/2023]
Abstract
The rate of global environmental change is unprecedented, with climate change causing an increase in the oscillation and intensification of various abiotic stress factors that have negative impacts on crop production. This issue has become an alarming global concern, especially for countries already facing the threat of food insecurity. Abiotic stressors, such as drought, salinity, extreme temperatures, and metal (nanoparticle) toxicities, are recognized as major constraints in agriculture, and are closely associated with the crop yield penalty and losses in food supply. In order to combat abiotic stress, it is important to understand how plant organs adapt to changing conditions, as this can help produce more stress-resistant or stress-tolerant plants. The investigation of plant tissue ultrastructure and subcellular components can provide valuable insights into plant responses to abiotic stress-related stimuli. In particular, the columella cells (statocytes) of the root cap exhibit a unique architecture that is easily recognizable under a transmission electron microscope, making them a useful experimental model for ultrastructural observations. In combination with the assessment of plant oxidative/antioxidative status, both approaches can shed more light on the cellular and molecular mechanisms involved in plant adaptation to environmental cues. This review summarizes life-threatening factors of the changing environment that lead to stress-related damage to plants, with an emphasis on their subcellular components. Additionally, selected plant responses to such conditions in the context of their ability to adapt and survive in a challenging environment are also described.
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Affiliation(s)
- Hana Ďúranová
- AgroBioTech Research Centre, Slovak University of Agriculture, Trieda Andreja Hlinku 2, 949 76 Nitra, Slovakia;
| | - Veronika Šimora
- AgroBioTech Research Centre, Slovak University of Agriculture, Trieda Andreja Hlinku 2, 949 76 Nitra, Slovakia;
| | - Ľuba Ďurišová
- Institute of Plant and Environmental Sciences, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Trieda Andreja Hlinku 2, 949 76 Nitra, Slovakia; (Ľ.Ď.); (M.K.)
| | - Lucia Olexiková
- Agricultural and Food Centre (NPPC), Research Institute for Animal Production Nitra, Hlohovecká 2, 951 41 Lužianky, Slovakia;
| | - Marek Kovár
- Institute of Plant and Environmental Sciences, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Trieda Andreja Hlinku 2, 949 76 Nitra, Slovakia; (Ľ.Ď.); (M.K.)
| | - Miroslava Požgajová
- AgroBioTech Research Centre, Slovak University of Agriculture, Trieda Andreja Hlinku 2, 949 76 Nitra, Slovakia;
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Lorenz C, Bianchi E, Poggiali G, Alemanno G, Benesperi R, Brucato JR, Garland S, Helbert J, Loppi S, Lorek A, Maturilli A, Papini A, de Vera JP, Baqué M. Survivability of the lichen Xanthoria parietina in simulated Martian environmental conditions. Sci Rep 2023; 13:4893. [PMID: 36966209 PMCID: PMC10039903 DOI: 10.1038/s41598-023-32008-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/21/2023] [Indexed: 03/27/2023] Open
Abstract
Xanthoria parietina (L.) Th. Fr. is a widely spread foliose lichen showing high tolerance against UV-radiation thanks to parietin, a secondary lichen substance. We exposed samples of X. parietina under simulated Martian conditions for 30 days to explore its survivability. The lichen's vitality was monitored via chlorophyll a fluorescence that gives an indication for active light reaction of photosynthesis, performing in situ and after-treatment analyses. Raman spectroscopy and TEM were used to evaluate carotenoid preservation and possible variations in the photobiont's ultrastructure respectively. Significant differences in the photo-efficiency between UV irradiated samples and dark-kept samples were observed. Fluorescence values correlated with temperature and humidity day-night cycles. The photo-efficiency recovery showed that UV irradiation caused significant effects on the photosynthetic light reaction. Raman spectroscopy showed that the carotenoid signal from UV exposed samples decreased significantly after the exposure. TEM observations confirmed that UV exposed samples were the most affected by the treatment, showing chloroplastidial disorganization in photobionts' cells. Overall, X. parietina was able to survive the simulated Mars conditions, and for this reason it may be considered as a candidate for space long-term space exposure and evaluations of the parietin photodegradability.
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Affiliation(s)
- Christian Lorenz
- Department of Biology, University of Florence, Via la Pira 4, 50121, Florence, Italy
| | - Elisabetta Bianchi
- Department of Biology, University of Florence, Via la Pira 4, 50121, Florence, Italy
| | - Giovanni Poggiali
- LESIA-Observatoire de Paris, CNRS, Université PSL, Sorbonne Université, Université de Paris, 5 Place Jules Janssen, 92190, Meudon, France
- INAF-Astrophysical Observatory of Arcetri, Largo E. Fermi 5, 50125, Florence, Italy
| | - Giulia Alemanno
- Planetary Laboratories Department, Institute of Planetary Research, German Aerospace Center (DLR), Ruthefordstraße 2, 12489, Berlin, Germany
| | - Renato Benesperi
- Department of Biology, University of Florence, Via la Pira 4, 50121, Florence, Italy
| | - John Robert Brucato
- INAF-Astrophysical Observatory of Arcetri, Largo E. Fermi 5, 50125, Florence, Italy.
| | - Stephen Garland
- Planetary Laboratories Department, Institute of Planetary Research, German Aerospace Center (DLR), Ruthefordstraße 2, 12489, Berlin, Germany
| | - Jörn Helbert
- Planetary Laboratories Department, Institute of Planetary Research, German Aerospace Center (DLR), Ruthefordstraße 2, 12489, Berlin, Germany
| | - Stefano Loppi
- Department of Environmental Sciences, University of Siena, Via P. A. Mattioli 4, 53100, Siena, Italy
| | - Andreas Lorek
- Planetary Laboratories Department, Institute of Planetary Research, German Aerospace Center (DLR), Ruthefordstraße 2, 12489, Berlin, Germany
| | - Alessandro Maturilli
- Planetary Laboratories Department, Institute of Planetary Research, German Aerospace Center (DLR), Ruthefordstraße 2, 12489, Berlin, Germany
| | - Alessio Papini
- Department of Biology, University of Florence, Via la Pira 4, 50121, Florence, Italy
| | - Jean-Pierre de Vera
- Microgravity User Support Center (MUSC), Space Operations and Astronaut Training, German Aerospace Center (DLR), Linder Höhe, 51147, Cologne, Germany
| | - Mickaël Baqué
- Planetary Laboratories Department, Institute of Planetary Research, German Aerospace Center (DLR), Ruthefordstraße 2, 12489, Berlin, Germany
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Mori-Moriyama N, Yoshitomi T, Sato N. Acyl plastoquinol is a major cyanobacterial substance that co-migrates with triacylglycerol in thin-layer chromatography. Biochem Biophys Res Commun 2023; 641:18-26. [PMID: 36516585 DOI: 10.1016/j.bbrc.2022.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022]
Abstract
Various studies have suggested the presence of triacylglycerol in cyanobacteria, but no convincing evidence exists. We purified a substance co-migrating with triacylglycerol in thin-layer chromatography and determined its structure using mass spectrometry, gas chromatography, and 1H and 13C NMR. The major components were palmitoyl and stearoyl plastoquinols (acyl plastoquinol). Acyl plastoquinol has never been described before, although acyloxy derivative of plastoquione has been described as plastoquinone B. The level of acyl plastoquinol was 0.4% of the total lipids. We still do not have clear evidence for the presence of triacylglycerol. If present, the maximum triacylglycerol level must be at most 10% of acyl plastoquinol. The Synechocystis Slr2103 protein was suggested to synthesize triacylglycerol, but the product could be acyl plastoquinol. The possible roles of this novel compound in photosynthesis should be a new focus of research.
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Affiliation(s)
- Natsumi Mori-Moriyama
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902, Japan.
| | - Toru Yoshitomi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902, Japan.
| | - Naoki Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902, Japan.
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5
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Chen G, Harwood JL, Lemieux MJ, Stone SJ, Weselake RJ. Acyl-CoA:diacylglycerol acyltransferase: Properties, physiological roles, metabolic engineering and intentional control. Prog Lipid Res 2022; 88:101181. [PMID: 35820474 DOI: 10.1016/j.plipres.2022.101181] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/31/2022] [Accepted: 07/04/2022] [Indexed: 12/15/2022]
Abstract
Acyl-CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the last reaction in the acyl-CoA-dependent biosynthesis of triacylglycerol (TAG). DGAT activity resides mainly in membrane-bound DGAT1 and DGAT2 in eukaryotes and bifunctional wax ester synthase-diacylglycerol acyltransferase (WSD) in bacteria, which are all membrane-bound proteins but exhibit no sequence homology to each other. Recent studies also identified other DGAT enzymes such as the soluble DGAT3 and diacylglycerol acetyltransferase (EaDAcT), as well as enzymes with DGAT activities including defective in cuticular ridges (DCR) and steryl and phytyl ester synthases (PESs). This review comprehensively discusses research advances on DGATs in prokaryotes and eukaryotes with a focus on their biochemical properties, physiological roles, and biotechnological and therapeutic applications. The review begins with a discussion of DGAT assay methods, followed by a systematic discussion of TAG biosynthesis and the properties and physiological role of DGATs. Thereafter, the review discusses the three-dimensional structure and insights into mechanism of action of human DGAT1, and the modeled DGAT1 from Brassica napus. The review then examines metabolic engineering strategies involving manipulation of DGAT, followed by a discussion of its therapeutic applications. DGAT in relation to improvement of livestock traits is also discussed along with DGATs in various other eukaryotic organisms.
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Affiliation(s)
- Guanqun Chen
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada.
| | - John L Harwood
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Membrane Protein Disease Research Group, Edmonton T6G 2H7, Canada
| | - Scot J Stone
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
| | - Randall J Weselake
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada
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6
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do Carmo Cesário C, Soares J, Cossolin JFS, Almeida AVM, Bermudez Sierra JJ, de Oliveira Leite M, Nunes MC, Serrão JE, Martins MA, Dos Reis Coimbra JS. Biochemical and morphological characterization of freshwater microalga Tetradesmus obliquus (Chlorophyta: Chlorophyceae). PROTOPLASMA 2022; 259:937-948. [PMID: 34643788 DOI: 10.1007/s00709-021-01712-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 09/29/2021] [Indexed: 06/13/2023]
Abstract
Tetradesmus is a microalgal genus with biotechnological potential due to its rapid production of biomass, which is plenty in proteins, carbohydrates, lipids, and bioactives. However, its morphology and physiology need to be determined to guide better research to optimize the species cultivation and biocompounds processing. Thus, this study describes the biochemistry and morphology of the strain Tetradesmus obliquus BR003, isolated from a sample of freshwater reservoirs in a Brazilian municipality. In the T. obliquus BR003 dry biomass, we identified 61.6% unsaturated fatty acids, and 3.4% saturated fatty acids. Regarding other compounds, 28.50 ± 1.47 g soluble proteins/100 g, 0.14 ± 0.009 g carotenoids/100 g, 0.76 ± 0.013 g chlorophyll a/100 g, and 0.42 ± 0.015 g chlorophyll b/100 g with a chlorophyll a/b ratio of 1.8 were detected. The main chemical elements found were S, Mg, and P. The cells of BR003 were elliptically curved at the ends and without appendages. Histochemical tests showed carbohydrates distributed in the cytoplasm and pyrenoids, some lipid droplets, and proteins. The cytoplasm is rich in vacuoles, rough endoplasmic reticulum, mitochondria, and chloroplasts. The nucleus has a predominance of decondensed chromatin, and the cell wall has three layers. Chloroplasts have many starch granules and may be associated with a spherical central pyrenoid. To the best of our knowledge, this was the first biochemical description combined with ultrastructural morphological characterization of the strain T. obliquus BR003, grown under standard conditions, to demonstrate specific characteristics of the species.
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Affiliation(s)
| | - Jimmy Soares
- Department of Agricultural Engineering, Universidade Federal de Viçosa, Viçosa, Brazil
| | | | | | | | | | - Maria Clara Nunes
- Department of Veterinary Medicine, Universidade Federal de Viçosa, Viçosa, Brazil
| | - José Eduardo Serrão
- Department of General Biology, Universidade Federal de Viçosa, Viçosa, Brazil.
| | - Marcio Arêdes Martins
- Department of Agricultural Engineering, Universidade Federal de Viçosa, Viçosa, Brazil
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7
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Carro MDLM, Gonorazky G, Soto D, Mamone L, Bagnato C, Pagnussat LA, Beligni MV. Expression of Chlamydomonas reinhardtii chloroplast diacylglycerol acyltransferase 3 is induced by light in concert with triacylglycerol accumulation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 110:262-276. [PMID: 35043497 DOI: 10.1111/tpj.15671] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 12/15/2021] [Accepted: 01/09/2022] [Indexed: 06/14/2023]
Abstract
Considerable progress has been made towards the understanding of triacylglycerol (TAG) accumulation in algae. One key aspect is finding conditions that trigger TAG production without reducing cell division. Previously, we identified a soluble diacylglycerol acyltransferase (DGAT), related to plant DGAT3, with heterologous DGAT activity. In this work, we demonstrate that Chlamydomonas reinhardtii DGAT3 localizes to the chloroplast and that its expression is induced by light, in correspondence with TAG accumulation. Dgat3 mRNAs and TAGs increase in both wild-type and starch-deficient cells grown with acetate upon transferring them from dark or low light to higher light levels, albeit affected by the particularities of each strain. The response of dgat3 mRNAs and TAGs to light depends on the pre-existing levels of TAGs, suggesting the existence of a negative regulatory loop in the synthesis pathway, although an effect of TAG turnover cannot be ruled out. Altogether, these results hint towards a possible role of DGAT3 in light-dependent TAG accumulation in C. reinhardtii.
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Affiliation(s)
- María de Las Mercedes Carro
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
| | - Gabriela Gonorazky
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
| | - Débora Soto
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
| | - Leandro Mamone
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
| | - Carolina Bagnato
- Instituto de Energía y Desarrollo Sustentable (IEDS), Comisión Nacional de Energía Atómica, Centro Atómico Bariloche, 8400, San Carlos de Bariloche, Argentina
| | - Luciana A Pagnussat
- Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, B7620EMA, Balcarce, Argentina
| | - María Verónica Beligni
- Instituto de Investigaciones Biológicas (IIB-CONICET-UNMdP), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, B7608FBY, Mar del Plata, Argentina
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8
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Limited fatty-acid supply from the plastid and active catabolism of triacylglycerol prevent the accumulation of triacylglycerol in Coccomyxa sp. strain Obi grown under nitrogen-replete conditions. ALGAL RES 2022. [DOI: 10.1016/j.algal.2021.102620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Li-Beisson Y. Editorial Feature: Meet the PCP Editor-Yonghua Li-Beisson. PLANT & CELL PHYSIOLOGY 2022; 63:151-153. [PMID: 34971395 DOI: 10.1093/pcp/pcab163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 11/04/2021] [Accepted: 11/10/2021] [Indexed: 06/14/2023]
Affiliation(s)
- Yonghua Li-Beisson
- CEA - Institute of Biosciences and Biotechnology of Aix Marseille, CEA Cadarache, Bat 1900, Saint Paul lez Durance 13108, France
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Ma X, Mi Y, Zhao C, Wei Q. A comprehensive review on carbon source effect of microalgae lipid accumulation for biofuel production. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151387. [PMID: 34740661 DOI: 10.1016/j.scitotenv.2021.151387] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/12/2021] [Accepted: 10/29/2021] [Indexed: 06/13/2023]
Abstract
Energy is a major driving force for the economic development. Due to the scarcity of fossil fuels and negative impact on the environment, it is important to develop renewable and sustainable energy sources for humankind. Microalgae as the primary feedstock for biodiesel has shown great application potential. However, lipid yield from microalgae is limited by the upstream cost, which restrain the realization of large-scale biofuel production. The modification of lipid-rich microalgae cell has become the focus over the last few decades to improve the lipid content and productivity of microalgae. Carbon is a vital nutrient that regulates the growth and metabolism of microalgae. Different carbon sources are assimilated by microalgae cells via different pathways. Inorganic carbon sources are mainly used through the CO2-concentrating mechanisms (CCMs), while organic carbon sources are absorbed by microalgae mainly through the Pentose Phosphate (PPP) Pathway and the Embden-Meyerhof-Pranas (EMP) pathway. Therefore, the addition of carbon source has a significant impact on the production of microalgae biomass and lipid accumulation. In this paper, mechanisms of lipid synthesis and carbon uptake of microalgae were introduced, and the effects of different carbon conditions (types, concentrations, and addition methods) on lipid accumulation in microalgal biomass production and biodiesel production were comprehensively discussed. This review also highlights the recent advances in microalgae lipid cultivation with large-scale commercialization and the development prospects of biodiesel production. Current challenges and constructive suggestions are proposed on cost-benefit concerns in large-scale production of microalgae biodiesel.
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Affiliation(s)
- Xiangmeng Ma
- School of Resources, Environment and Materials, Guangxi University, Nanning, Guangxi 530004, China; Guangxi Key Laboratory of Electrochemical Energy Materials, Nanning, Guangxi 530004, China
| | - Yuwei Mi
- School of Resources, Environment and Materials, Guangxi University, Nanning, Guangxi 530004, China
| | - Chen Zhao
- China Construction Fifth Engineering Division Corp., Ltd, 9 Kaixuan Rd, Liangqing District, Nanning, Guangxi 530000, China
| | - Qun Wei
- School of Resources, Environment and Materials, Guangxi University, Nanning, Guangxi 530004, China.
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11
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Genetic engineering of microalgae for enhanced lipid production. Biotechnol Adv 2021; 52:107836. [PMID: 34534633 DOI: 10.1016/j.biotechadv.2021.107836] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/09/2021] [Accepted: 09/09/2021] [Indexed: 12/24/2022]
Abstract
Microalgae have the potential to become microbial cell factories for lipid production. Their ability to convert sunlight and CO2 into valuable lipid compounds has attracted interest from cosmetic, biofuel, food and feed industries. In order to make microalgae-derived products cost-effective and commercially competitive, enhanced growth rates and lipid productivities are needed, which require optimization of cultivation systems and strain improvement. Advances in genetic tool development and omics technologies have increased our understanding of lipid metabolism, which has opened up possibilities for targeted metabolic engineering. In this review we provide a comprehensive overview on the developments made to genetically engineer microalgal strains over the last 30 years. We focus on the strategies that lead to an increased lipid content and altered fatty acid profile. These include the genetic engineering of the fatty acid synthesis pathway, Kennedy pathway, polyunsaturated fatty acid and triacylglycerol metabolisms and fatty acid catabolism. Moreover, genetic engineering of specific transcription factors, NADPH generation and central carbon metabolism, which lead to increase of lipid accumulation are also reviewed.
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12
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Iwai M, Yamada-Oshima Y, Asami K, Kanamori T, Yuasa H, Shimojima M, Ohta H. Recycling of the major thylakoid lipid MGDG and its role in lipid homeostasis in Chlamydomonas reinhardtii. PLANT PHYSIOLOGY 2021; 187:1341-1356. [PMID: 34618048 PMCID: PMC8566231 DOI: 10.1093/plphys/kiab340] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 06/24/2021] [Indexed: 06/01/2023]
Abstract
Monogalactosyldiacylglycerol (MGDG), the most abundant lipid in thylakoid membranes, is involved in photosynthesis and chloroplast development. MGDG lipase has an important role in lipid remodeling in Chlamydomonas reinhardtii. However, the process related to turnover of the lysogalactolipid that results from MGDG degradation, monogalactosylmonoacylglycerol (MGMG), remains to be clarified. Here we identified a homolog of Arabidopsis thaliana lysophosphatidylcholine acyltransferase (LPCAT) and characterized two independent knockdown (KD) alleles in C. reinhardtii. The enzyme designated as C. reinhardtiiLysolipid Acyltransferase 1 (CrLAT1) has a conserved membrane-bound O-acyl transferase domain. LPCAT from Arabidopsis has a key role in deacylation of phosphatidylcholine (PC). Chlamydomonas reinhardtii, however, lacks PC, and thus we hypothesized that CrLAT1 has some other important function in major lipid flow in this organism. In the CrLAT1 KD mutants, the amount of MGMG was increased, but triacylglycerols (TAGs) were decreased. The proportion of more saturated 18:1 (9) MGDG was lower in the KD mutants than in their parental strain, CC-4533. In contrast, the proportion of MGMG has decreased in the CrLAT1 overexpression (OE) mutants, and the proportion of 18:1 (9) MGDG was higher in the OE mutants than in the empty vector control cells. Thus, CrLAT1 is involved in the recycling of MGDG in the chloroplast and maintains lipid homeostasis in C. reinhardtii.
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Affiliation(s)
- Masako Iwai
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Yui Yamada-Oshima
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Kota Asami
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Takashi Kanamori
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Hideya Yuasa
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Mie Shimojima
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Hiroyuki Ohta
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
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13
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Li-Beisson Y, Kong F, Wang P, Lee Y, Kang BH. The disassembly of lipid droplets in Chlamydomonas. THE NEW PHYTOLOGIST 2021; 231:1359-1364. [PMID: 34028037 DOI: 10.1111/nph.17505] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 05/07/2021] [Indexed: 06/12/2023]
Abstract
Lipid droplets (LDs) are ubiquitous and specialized organelles in eukaryotic cells. Consisting of a triacylglycerol core surrounded by a monolayer of membrane lipids, LDs are decorated with proteins and have myriad functions, from carbon/energy storage to membrane lipid remodeling and signal transduction. The biogenesis and turnover of LDs are therefore tightly coordinated with cellular metabolic needs in a fluctuating environment. Lipid droplet turnover requires remodeling of the protein coat, lipolysis, autophagy and fatty acid β-oxidation. Several key components of these processes have been identified in Chlamydomonas (Chlamydomonas reinhardtii), including the major lipid droplet protein, a CXC-domain containing regulatory protein, the phosphatidylethanolamine-binding DTH1 (DELAYED IN TAG HYDROLYSIS1), two lipases and two enzymes involved in fatty acid β-oxidation. Here, we review LD turnover and discuss its physiological significance in Chlamydomonas, a major model green microalga in research on algal oil.
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Affiliation(s)
- Yonghua Li-Beisson
- CEA, CNRS, BIAM, Institut de Biosciences et Biotechnologies Aix-Marseille, CEA Cadarache, Aix-Marseille Univ, Saint Paul-Lez-Durance, 13108, France
| | - Fantao Kong
- School of Bioengineering, Dalian University of Technology, Dalian, 116024, China
| | - Pengfei Wang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, 999077, China
| | - Youngsook Lee
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Byung-Ho Kang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, 999077, China
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14
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Chen H, Wang Q. Regulatory mechanisms of lipid biosynthesis in microalgae. Biol Rev Camb Philos Soc 2021; 96:2373-2391. [PMID: 34101323 DOI: 10.1111/brv.12759] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 02/01/2023]
Abstract
Microalgal lipids are highly promising feedstocks for biofuel production. Microalgal lipids, especially triacylglycerol, and practical applications of these compounds have received increasing attention in recent years. For the commercial use of microalgal lipids to be feasible, many fundamental biological questions must be addressed based on detailed studies of algal biology, including how lipid biosynthesis occurs and is regulated. Here, we review the current understanding of microalgal lipid biosynthesis, with a focus on the underlying regulatory mechanisms. We also present possible solutions for overcoming various obstacles to understanding the basic biology of microalgal lipid biosynthesis and the practical application of microalgae-based lipids. This review will provide a theoretical reference for both algal researchers and decision makers regarding the future directions of microalgal research, particularly pertaining to microalgal-based lipid biosynthesis.
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Affiliation(s)
- Hui Chen
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China
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15
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Sato N. Are Cyanobacteria an Ancestor of Chloroplasts or Just One of the Gene Donors for Plants and Algae? Genes (Basel) 2021; 12:genes12060823. [PMID: 34071987 PMCID: PMC8227023 DOI: 10.3390/genes12060823] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/08/2021] [Accepted: 05/25/2021] [Indexed: 12/04/2022] Open
Abstract
Chloroplasts of plants and algae are currently believed to originate from a cyanobacterial endosymbiont, mainly based on the shared proteins involved in the oxygenic photosynthesis and gene expression system. The phylogenetic relationship between the chloroplast and cyanobacterial genomes was important evidence for the notion that chloroplasts originated from cyanobacterial endosymbiosis. However, studies in the post-genomic era revealed that various substances (glycolipids, peptidoglycan, etc.) shared by cyanobacteria and chloroplasts are synthesized by different pathways or phylogenetically unrelated enzymes. Membranes and genomes are essential components of a cell (or an organelle), but the origins of these turned out to be different. Besides, phylogenetic trees of chloroplast-encoded genes suggest an alternative possibility that chloroplast genes could be acquired from at least three different lineages of cyanobacteria. We have to seriously examine that the chloroplast genome might be chimeric due to various independent gene flows from cyanobacteria. Chloroplast formation could be more complex than a single event of cyanobacterial endosymbiosis. I present the “host-directed chloroplast formation” hypothesis, in which the eukaryotic host cell that had acquired glycolipid synthesis genes as an adaptation to phosphate limitation facilitated chloroplast formation by providing glycolipid-based membranes (pre-adaptation). The origins of the membranes and the genome could be different, and the origin of the genome could be complex.
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Affiliation(s)
- Naoki Sato
- Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
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16
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Young DY, Shachar-Hill Y. Large fluxes of fatty acids from membranes to triacylglycerol and back during N-deprivation and recovery in Chlamydomonas. PLANT PHYSIOLOGY 2021; 185:796-814. [PMID: 33822218 PMCID: PMC8133548 DOI: 10.1093/plphys/kiaa071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
Microalgae accumulate triacylglycerol (TAG) during nutrient deprivation and break it down after nutrient resupply, and these processes involve dramatic shifts in cellular carbon allocation. Due to the importance of algae in the global carbon cycle, and the potential of algal lipids as feedstock for chemical and fuel production, these processes are of both ecophysiological and biotechnological importance. However, the metabolism of TAG is not well understood, particularly the contributions of fatty acids (FAs) from different membrane lipids to TAG accumulation and the fate of TAG FAs during degradation. Here, we used isotopic labeling time course experiments on Chlamydomonas reinhardtii to track FA synthesis and transfer between lipid pools during nitrogen (N)-deprivation and resupply. When cells were labeled before N-deprivation, total levels of label in cellular FAs were unchanged during subsequent N-deprivation and later resupply, despite large fluxes into and out of TAG and membrane lipid pools. Detailed analyses of FA levels and labeling revealed that about one-third of acyl chains accumulating in TAG during N-deprivation derive from preexisting membrane lipids, and in total, at least 45% of TAG FAs passed through membrane lipids at one point. Notably, most acyl chains in membrane lipids during recovery after N-resupply come from TAG. Fluxes of polyunsaturated FAs from plastidic membranes into TAG during N-deprivation were particularly noteworthy. These findings demonstrate a high degree of integration of TAG and membrane lipid metabolism and highlight a role for TAG in storage and supply of membrane lipid components.
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Affiliation(s)
- Danielle Yvonne Young
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
| | - Yair Shachar-Hill
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
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17
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Multidisciplinary integrated characterization of a native Chlorella-like microalgal strain isolated from a municipal landfill leachate. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Sato N, Toyoshima M. Dynamism of Metabolic Carbon Flow of Starch and Lipids in Chlamydomonas debaryana. FRONTIERS IN PLANT SCIENCE 2021; 12:646498. [PMID: 33868347 PMCID: PMC8047662 DOI: 10.3389/fpls.2021.646498] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 03/08/2021] [Indexed: 06/01/2023]
Abstract
Microalgae have the potential to recycle CO2 as starch and triacylglycerol (TAG), which provide alternative source of biofuel and high added-value chemicals. Starch accumulates in the chloroplast, whereas TAG accumulates in the cytoplasmic lipid droplets (LD). Preferential accumulation of starch or TAG may be achieved by switching intracellular metabolic carbon flow, but our knowledge on this control remains limited. Are these two products mutually exclusive? Or, does starch act as a precursor to TAG synthesis, or vice versa? To answer these questions, we analyzed carbon flow in starch and lipids using a stable isotope 13C in Chlamydomonas debaryana NIES-2212, which accumulates, without nutrient limitation, starch in the exponential growth phase and TAG in the stationary phase. Pulse labeling experiments as well as pulse labeling and chase experiments were conducted, and then, gas chromatography-mass spectrometry (GC-MS) analysis was performed on starch-derived glucose and lipid-bound fatty acids. We exploited the previously developed method of isotopomer analysis to estimate the proportion of various pools with different isotopic abundance. Starch turned over rapidly to provide carbon for the synthesis of fatty acids in the exponential phase cells. Most fatty acids showed rapid and slow components of metabolism, whereas oleic acid decayed according to a single exponential curve. Highly labeled population of fatty acids that accumulated during the initial labeling decreased rapidly, and replaced by low abundance population during the chase time, indicating that highly labeled fatty acids were degraded and the resulting carbons were re-used in the re-synthesis with about 9-fold unlabeled, newly fixed carbons. Elongation of C16-C18 acids in vivo was indicated by partially labeled C18 acids. The accumulation of TAG in the stationary growth phase was accounted for by both de novo synthesis and remodeling of membrane lipids. These results suggest that de novo synthesis of starch and TAG was rapid and transient, and also almost independent to each other, but there is a pool of starch quickly turning over for the synthesis of fatty acids. Fatty acids were also subject to re-synthesis. Evidence was also provided for remodeling of lipids, namely, re-use of acyl groups in polar lipids for TAG synthesis.
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19
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Ohashi Y, Mori T, Igawa T. Behavior of filamentous temperature-sensitive Z2 (FtsZ2) in the male gametophyte during sexual reproduction processes of flowering plants. PROTOPLASMA 2020; 257:1201-1210. [PMID: 32300955 DOI: 10.1007/s00709-020-01503-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/20/2020] [Indexed: 06/11/2023]
Abstract
Filamentous temperature-sensitive Z (FtsZ) is a critical division protein in bacteria that functions in forming a Z-ring structure to constrict the cell. Since the establishment of the plastid by endosymbiosis of a cyanobacterium into a eukaryotic cell, division via Z-ring formation has been conserved in the plastids of flowering plants. The FtsZ gene was transferred from the cyanobacterial ancestor of plastids to the eukaryotic nuclear genome during evolution, and flowering plants evolved two FtsZ homologs, FtsZ1 and FtsZ2, which are involved in chloroplast division through distinct molecular functions. Regarding the behaviors of FtsZ in nonphotosynthetic cells, the plastid localization of FtsZ1 proteins in the cytoplasm of microspores and pollen vegetative cells but not in generative cells or sperm cells has been reported. On the other hand, the significant accumulation of FtsZ2 transcripts in generative cells has been reported. However, the synthesis of FtsZ2 in the male gamete has not been investigated. Additionally, FtsZ2 behavior has not been analyzed in pollen, a nonphotosynthetic male tissue. Here, we report FtsZ2 protein behaviors in the male gamete by analyzing the localization patterns of GFP-fused protein at various pollen developmental stages and in gametes during the fertilization process. Our results showed that FtsZ2 localization coincided with that of plastids. FtsZ2 protein in male gametes was almost absent, despite the presence of the transcripts. Moreover, transmission of paternal FtsZ2 transcripts to the zygote and endosperm was not observed.
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Affiliation(s)
- Yukino Ohashi
- Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo-shi, Chiba, 271-8510, Japan
| | - Toshiyuki Mori
- Department of Tropical Medicine and Parasitology, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Tomoko Igawa
- Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo-shi, Chiba, 271-8510, Japan.
- Plant Molecular Science Center, Chiba University, 648 Matsudo, Matsudo-shi, Chiba, 271-8510, Japan.
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20
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Lundquist PK, Shivaiah KK, Espinoza-Corral R. Lipid droplets throughout the evolutionary tree. Prog Lipid Res 2020; 78:101029. [PMID: 32348789 DOI: 10.1016/j.plipres.2020.101029] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/11/2020] [Accepted: 04/18/2020] [Indexed: 12/11/2022]
Abstract
Intracellular lipid droplets are utilized for lipid storage and metabolism in organisms as evolutionarily diverse as animals, fungi, plants, bacteria, and archaea. These lipid droplets demonstrate great diversity in biological functions and protein and lipid compositions, yet fundamentally share common molecular and ultrastructural characteristics. Lipid droplet research has been largely fragmented across the diversity of lipid droplet classes and sub-classes. However, we suggest that there is great potential benefit to the lipid community in better integrating the lipid droplet research fields. To facilitate such integration, we survey the protein and lipid compositions, functional roles, and mechanisms of biogenesis across the breadth of lipid droplets studied throughout the natural world. We depict the big picture of lipid droplet biology, emphasizing shared characteristics and unique differences seen between different classes. In presenting the known diversity of lipid droplets side-by-side it becomes necessary to offer for the first time a consistent system of categorization and nomenclature. We propose a division into three primary classes that reflect their sub-cellular location: i) cytoplasmic lipid droplets (CYTO-LDs), that are present in the eukaryotic cytoplasm, ii) prokaryotic lipid droplets (PRO-LDs), that exist in the prokaryotic cytoplasm, and iii) plastid lipid droplets (PL-LDs), that are found in plant plastids, organelles of photosynthetic eukaryotes. Within each class there is a remarkable array of sub-classes displaying various sizes, shapes and compositions. A more integrated lipid droplet research field will provide opportunities to better build on discoveries and accelerate the pace of research in ways that have not been possible.
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Affiliation(s)
- Peter K Lundquist
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA.
| | - Kiran-Kumar Shivaiah
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Roberto Espinoza-Corral
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
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21
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Yang M, Kong F, Xie X, Wu P, Chu Y, Cao X, Xue S. Galactolipid DGDG and Betaine Lipid DGTS Direct De Novo Synthesized Linolenate into Triacylglycerol in a Stress-Induced Starchless Mutant of Chlamydomonas reinhardtii. PLANT & CELL PHYSIOLOGY 2020; 61:851-862. [PMID: 32061132 DOI: 10.1093/pcp/pcaa012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/30/2020] [Indexed: 06/10/2023]
Abstract
The increasing demand for triacylglycerol (TAG) enriching polyunsaturated fatty acids (PUFAs) has led to a surge of interest in microalgal TAG metabolism. Polar membrane lipids serve as the desaturation carrier for PUFA, and the functional group of PUFA can be incorporated into TAG. Monogalactoglycerolipid has been found to provide the de novo synthesized oleate acyl group or the nascent polyunsaturated diacylglycerol backbone for TAG biosynthesis in the model green alga, Chlamydomonas reinhardtii. However, whether other membrane lipids take part in the formation of PUFA-attached TAG has not been clearly discovered. A time course study of glycerolipidomics in the starchless mutant of C. reinhardtii, BAFJ5, which hyper-accumulates TAG, revealed that digalactosyldiacylglycerol (DGDG) and diacylglycerol-N,N,N-trimethylhomoserine (DGTS) turned into the main components of membrane lipids, accounting for 62% of the total polar lipids, under nitrogen deprivation combined with high light conditions. In addition, the membrane lipid molecules DGDG 18:3n3/16:0 and DGTS 16:0/18:3n6 were presumed to be involved in the consecutive integration of the de novo synthesized linolenates into TAG. Based on the stoichiometry calculation, DGDG and DGTS were demonstrated to provide a major contribution to the accumulation of linolenate-attached TAG. Our study gives insights into the potential PUFA-attached TAG formation pathway mediated by the turnover of de novo synthesized DGDG and DGTS in the starchless mutant of Chlamydomonas.
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Affiliation(s)
- Miao Yang
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Fantao Kong
- Laboratory of Marine Biotechnology, School of Bioengineering, Dalian University of Technology, Dalian 116024, China
| | - Xi Xie
- Dalian Key Laboratory of Genetic Resources for Marine Shellfish, Liaoning Ocean and Fisheries Science Research Institute, Dalian 116023, China
| | - Peichun Wu
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yadong Chu
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xupeng Cao
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Song Xue
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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22
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Xu XY, Akbar S, Shrestha P, Venugoban L, Devilla R, Hussain D, Lee J, Rug M, Tian L, Vanhercke T, Singh SP, Li Z, Sharp PJ, Liu Q. A Synergistic Genetic Engineering Strategy Induced Triacylglycerol Accumulation in Potato ( Solanum tuberosum) Leaf. FRONTIERS IN PLANT SCIENCE 2020; 11:215. [PMID: 32210994 PMCID: PMC7069356 DOI: 10.3389/fpls.2020.00215] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 02/12/2020] [Indexed: 05/23/2023]
Abstract
Potato is the 4th largest staple food in the world currently. As a high biomass crop, potato harbors excellent potential to produce energy-rich compounds such as triacylglycerol as a valuable co-product. We have previously reported that transgenic potato tubers overexpressing WRINKLED1, DIACYLGLYCEROL ACYLTRANSFERASE 1, and OLEOSIN genes produced considerable levels of triacylglycerol. In this study, the same genetic engineering strategy was employed on potato leaves. The overexpression of Arabidopsis thaliana WRINKED1 under the transcriptional control of a senescence-inducible promoter together with Arabidopsis thaliana DIACYLGLYCEROL ACYLTRANSFERASE 1 and Sesamum indicum OLEOSIN driven by the Cauliflower Mosaic Virus 35S promoter and small subunit of Rubisco promoter respectively, resulted in an approximately 30- fold enhancement of triacylglycerols in the senescent transgenic potato leaves compared to the wild type. The increase of triacylglycerol in the transgenic potato leaves was accompanied by perturbations of carbohydrate accumulation, apparent in a reduction in starch content and increased total soluble sugars, as well as changes of polar membrane lipids at different developmental stages. Microscopic and biochemical analysis further indicated that triacylglycerols and lipid droplets could not be produced in chloroplasts, despite the increase and enlargement of plastoglobuli at the senescent stage. Possibly enhanced accumulation of fatty acid phytyl esters in the plastoglobuli were reflected in transgenic potato leaves relative to wild type. It is likely that the plastoglobuli may have hijacked some of the carbon as the result of WRINKED1 expression, which could be a potential factor restricting the effective accumulation of triacylglycerols in potato leaves. Increased lipid production was also observed in potato tubers, which may have affected the tuberization to a certain extent. The expression of transgenes in potato leaf not only altered the carbon partitioning in the photosynthetic source tissue, but also the underground sink organs which highly relies on the leaves in development and energy deposition.
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Affiliation(s)
- Xiao-yu Xu
- CSIRO Agriculture and Food, Canberra, ACT, Australia
- Plant Breeding Institute and Sydney Institute of Agriculture, School of Life and Environmental Sciences, The University of Sydney, Camperdown, NSW, Australia
| | - Sehrish Akbar
- CSIRO Agriculture and Food, Canberra, ACT, Australia
| | | | | | | | - Dawar Hussain
- CSIRO Agriculture and Food, Canberra, ACT, Australia
| | - Jiwon Lee
- Center for Advanced Microscopy, The Australian National University, Canberra, ACT, Australia
| | - Melanie Rug
- Center for Advanced Microscopy, The Australian National University, Canberra, ACT, Australia
| | - Lijun Tian
- CSIRO Agriculture and Food, Canberra, ACT, Australia
| | | | | | - Zhongyi Li
- CSIRO Agriculture and Food, Canberra, ACT, Australia
| | - Peter J. Sharp
- Plant Breeding Institute and Sydney Institute of Agriculture, School of Life and Environmental Sciences, The University of Sydney, Camperdown, NSW, Australia
| | - Qing Liu
- CSIRO Agriculture and Food, Canberra, ACT, Australia
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23
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Yoshitomi T, Kaminaga S, Sato N, Toyoshima M, Moriyama T, Yoshimoto K. Formation of Spherical Palmelloid Colony with Enhanced Lipid Accumulation by Gel Encapsulation of Chlamydomonas debaryana NIES-2212. PLANT & CELL PHYSIOLOGY 2020; 61:158-168. [PMID: 31589321 DOI: 10.1093/pcp/pcz188] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 09/20/2019] [Indexed: 06/10/2023]
Abstract
Microalgae such as Chlamydomonas reinhardtii accumulate triacylglycerol (TAG), which is a potential source of biofuels, under stress conditions such as nitrogen deprivation, whereas Chlamydomonas debaryana NIES-2212 has previously been identified and characterized as one of the rare species of Chlamydomonas, which massively accumulates TAG in the stationary phase without external stress. As the high density of the cells in the stationary phase was supposed to act as a trigger for the accumulation of TAG in C. debaryana, in this study, C. debaryana was encapsulated in a Ca2+-alginate gel for the culture with high cell density. We discovered that the growth of the encapsulated cells resulted in the formation of spherical palmelloid colonies with high cell density, where daughter cells with truncated flagella remained wrapped within the mother cell walls. Interestingly, gel encapsulation markedly promoted proliferation of C. debaryana cells, and the encapsulated cells reached the stationary phase earlier than that of the free-living cells. Gel encapsulation also enhanced TAG accumulation. Gene expression analysis revealed that two genes of acyltransferases, DGAT1 and DGTT3, were upregulated in the stationary phase of free-living C. debaryana. In addition, the gene expression of these acyltransferases increased earlier in the encapsulated cells than that in the free-living cells. The enhanced production of TAG by alginate gel encapsulation was not found in C. reinhardtii which is known to use a different repertoire of acyltransferases in lipid accumulation.
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Affiliation(s)
- Toru Yoshitomi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902 Japan
| | - Saeko Kaminaga
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902 Japan
| | - Naoki Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902 Japan
| | - Masakazu Toyoshima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902 Japan
| | - Takashi Moriyama
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902 Japan
| | - Keitaro Yoshimoto
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902 Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902 Japan
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24
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Ran W, Wang H, Liu Y, Qi M, Xiang Q, Yao C, Zhang Y, Lan X. Storage of starch and lipids in microalgae: Biosynthesis and manipulation by nutrients. BIORESOURCE TECHNOLOGY 2019; 291:121894. [PMID: 31387839 DOI: 10.1016/j.biortech.2019.121894] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 05/28/2023]
Abstract
Microalgae accumulate starch and lipid as storage metabolites under nutrient depletion, which can be used as sustainable feedstock for biorefinery. Omics analysis coupled with enzymatic and genetic verifications uncovered a partial picture of pathways and important enzymes or regulators related to starch and lipid biosynthesis as well as the carbon partitioning between them under nutrient depletion conditions. Depletion of macronutrients (N, P, and S) resulted in considerable enhancement of starch and/or lipid content in microalgae, but the accompanying declined photosynthesis hampered the achievements of high concentrations. This review summarized the current knowledge on the pathways and the committed steps as well as their carbon allocation involved in starch and lipid biosynthesis, and focused on the manipulation of different nutrients and the alleviation of oxidative stress for enhanced storage metabolites production. The biological and engineering approaches to cope with the conflict between biomass production and storage metabolites accumulation are proposed.
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Affiliation(s)
- Wenyi Ran
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Haitao Wang
- National Engineering Research Center of Seafood, School of Food Science and Technology, Dalian Polytechnic University, Dalian, Liaoning 116034, China
| | - Yinghui Liu
- Information Management Center of Sichuan University, Chengdu, Sichuan 610065, China
| | - Man Qi
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Qi Xiang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Changhong Yao
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China.
| | - Yongkui Zhang
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China
| | - Xianqiu Lan
- Department of Pharmaceutical & Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China
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25
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Vingiani GM, De Luca P, Ianora A, Dobson ADW, Lauritano C. Microalgal Enzymes with Biotechnological Applications. Mar Drugs 2019; 17:md17080459. [PMID: 31387272 PMCID: PMC6723882 DOI: 10.3390/md17080459] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/26/2022] Open
Abstract
Enzymes are essential components of biological reactions and play important roles in the scaling and optimization of many industrial processes. Due to the growing commercial demand for new and more efficient enzymes to help further optimize these processes, many studies are now focusing their attention on more renewable and environmentally sustainable sources for the production of these enzymes. Microalgae are very promising from this perspective since they can be cultivated in photobioreactors, allowing the production of high biomass levels in a cost-efficient manner. This is reflected in the increased number of publications in this area, especially in the use of microalgae as a source of novel enzymes. In particular, various microalgal enzymes with different industrial applications (e.g., lipids and biofuel production, healthcare, and bioremediation) have been studied to date, and the modification of enzymatic sequences involved in lipid and carotenoid production has resulted in promising results. However, the entire biosynthetic pathways/systems leading to synthesis of potentially important bioactive compounds have in many cases yet to be fully characterized (e.g., for the synthesis of polyketides). Nonetheless, with recent advances in microalgal genomics and transcriptomic approaches, it is becoming easier to identify sequences encoding targeted enzymes, increasing the likelihood of the identification, heterologous expression, and characterization of these enzymes of interest. This review provides an overview of the state of the art in marine and freshwater microalgal enzymes with potential biotechnological applications and provides future perspectives for this field.
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Affiliation(s)
- Giorgio Maria Vingiani
- Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, CAP80121 (NA) Villa Comunale, Italy
| | - Pasquale De Luca
- Research Infrastructure for Marine Biological Resources Department, Stazione Zoologica Anton Dohrn, CAP80121 (NA) Villa Comunale, Italy
| | - Adrianna Ianora
- Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, CAP80121 (NA) Villa Comunale, Italy
| | - Alan D W Dobson
- School of Microbiology, University College Cork, College Road, T12 YN60 Cork, Ireland
- Environmental Research Institute, University College Cork, Lee Road, T23XE10 Cork, Ireland
| | - Chiara Lauritano
- Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, CAP80121 (NA) Villa Comunale, Italy.
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Iwai M, Roth MS, Niyogi KK. Subdiffraction-resolution live-cell imaging for visualizing thylakoid membranes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:233-243. [PMID: 29982996 PMCID: PMC6150804 DOI: 10.1111/tpj.14021] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 06/18/2018] [Accepted: 06/25/2018] [Indexed: 05/19/2023]
Abstract
The chloroplast is the chlorophyll-containing organelle that produces energy through photosynthesis. Within the chloroplast is an intricate network of thylakoid membranes containing photosynthetic membrane proteins that mediate electron transport and generate chemical energy. Historically, electron microscopy (EM) has been a powerful tool for visualizing the macromolecular structure and organization of thylakoid membranes. However, an understanding of thylakoid membrane dynamics remains elusive because EM requires fixation and sectioning. To improve our knowledge of thylakoid membrane dynamics we need to consider at least two issues: (i) the live-cell imaging conditions needed to visualize active processes in vivo; and (ii) the spatial resolution required to differentiate the characteristics of thylakoid membranes. Here, we utilize three-dimensional structured illumination microscopy (3D-SIM) to explore the optimal imaging conditions for investigating the dynamics of thylakoid membranes in living plant and algal cells. We show that 3D-SIM is capable of examining broad characteristics of thylakoid structures in chloroplasts of the vascular plant Arabidopsis thaliana and distinguishing the structural differences between wild-type and mutant strains. Using 3D-SIM, we also visualize thylakoid organization in whole cells of the green alga Chlamydomonas reinhardtii. These data reveal that high light intensity changes thylakoid membrane structure in C. reinhardtii. Moreover, we observed the green alga Chromochloris zofingiensis and the moss Physcomitrella patens to show the applicability of 3D-SIM. This study demonstrates that 3D-SIM is a promising approach for studying the dynamics of thylakoid membranes in photoautotrophic organisms during photoacclimation processes.
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Affiliation(s)
- Masakazu Iwai
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Plant and Microbial Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720-3102, USA
- Contact Author: Masakazu Iwai
| | - Melissa S. Roth
- Department of Plant and Microbial Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720-3102, USA
| | - Krishna K. Niyogi
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Plant and Microbial Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720-3102, USA
- For correspondence ( or )
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Xu Y, Caldo KMP, Pal-Nath D, Ozga J, Lemieux MJ, Weselake RJ, Chen G. Properties and Biotechnological Applications of Acyl-CoA:diacylglycerol Acyltransferase and Phospholipid:diacylglycerol Acyltransferase from Terrestrial Plants and Microalgae. Lipids 2018; 53:663-688. [PMID: 30252128 DOI: 10.1002/lipd.12081] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 12/14/2022]
Abstract
Triacylglycerol (TAG) is the major storage lipid in most terrestrial plants and microalgae, and has great nutritional and industrial value. Since the demand for vegetable oil is consistently increasing, numerous studies have been focused on improving the TAG content and modifying the fatty-acid compositions of plant seed oils. In addition, there is a strong research interest in establishing plant vegetative tissues and microalgae as platforms for lipid production. In higher plants and microalgae, TAG biosynthesis occurs via acyl-CoA-dependent or acyl-CoA-independent pathways. Diacylglycerol acyltransferase (DGAT) catalyzes the last and committed step in the acyl-CoA-dependent biosynthesis of TAG, which appears to represent a bottleneck in oil accumulation in some oilseed species. Membrane-bound and soluble forms of DGAT have been identified with very different amino-acid sequences and biochemical properties. Alternatively, TAG can be formed through acyl-CoA-independent pathways via the catalytic action of membrane-bound phospholipid:diacylglycerol acyltransferase (PDAT). As the enzymes catalyzing the terminal steps of TAG formation, DGAT and PDAT play crucial roles in determining the flux of carbon into seed TAG and thus have been considered as the key targets for engineering oil production. Here, we summarize the most recent knowledge on DGAT and PDAT in higher plants and microalgae, with the emphasis on their physiological roles, structural features, and regulation. The development of various metabolic engineering strategies to enhance the TAG content and alter the fatty-acid composition of TAG is also discussed.
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Affiliation(s)
- Yang Xu
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
| | - Kristian Mark P Caldo
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
- Department of Biochemistry, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2H7, Canada
| | - Dipasmita Pal-Nath
- French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, 8499000, Israel
| | - Jocelyn Ozga
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2H7, Canada
| | - Randall J Weselake
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
| | - Guanqun Chen
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
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Zulu NN, Zienkiewicz K, Vollheyde K, Feussner I. Current trends to comprehend lipid metabolism in diatoms. Prog Lipid Res 2018. [DOI: 10.1016/j.plipres.2018.03.001] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Endoplasmic reticulum acyltransferase with prokaryotic substrate preference contributes to triacylglycerol assembly in Chlamydomonas. Proc Natl Acad Sci U S A 2018; 115:1652-1657. [PMID: 29382746 DOI: 10.1073/pnas.1715922115] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding the unique features of triacylglycerol (TAG) metabolism in microalgae may be necessary to realize the full potential of these organisms for biofuel and biomaterial production. In the unicellular green alga Chlamydomonas reinhardtii a chloroplastic (prokaryotic) pathway has been proposed to play a major role in TAG precursor biosynthesis. However, as reported here, C. reinhardtii contains a chlorophyte-specific lysophosphatidic acid acyltransferase, CrLPAAT2, that localizes to endoplasmic reticulum (ER) membranes. Unlike canonical, ER-located LPAATs, CrLPAAT2 prefers palmitoyl-CoA over oleoyl-CoA as the acyl donor substrate. RNA-mediated suppression of CrLPAAT2 indicated that the enzyme is required for TAG accumulation under nitrogen deprivation. Our findings suggest that Chlamydomonas has a distinct glycerolipid assembly pathway that relies on CrLPAAT2 to generate prokaryotic-like TAG precursors in the ER.
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Toyoshima M, Sato N. Optimization of triacylglycerol and starch production in Chlamydomonas debaryana NIES-2212 with regard to light intensity and CO2 concentration. MICROBIOLOGY-SGM 2018; 164:359-368. [PMID: 29458672 DOI: 10.1099/mic.0.000603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Triacylglycerol (TAG) and starch produced by micro-algae are potential sources of biofuel. Our previous studies showed that the unicellular green alga, Chlamydomonas debaryana NIES-2212, which is a rare species of Chlamydomonas that possesses phosphatidylcholine (PC), is a seed organism for the development of biofuel producers. This alga accumulates large amounts of TAG and starch under completely photo-autotrophic conditions during stationary phase without nutrient deprivation. The present study was performed to optimize the growth conditions of this alga with regard to light intensity and CO2 concentration to improve the efficiency of TAG and starch production. The growth rate of C. debaryana was greater at higher light intensity, although there was no significant difference in the final cell density of the culture. The highest contents of TAG and starch, approximately 200 fmol cell-1 and 600 pg cell-1, respectively, were achieved with a light intensity of 200 µmol m-2 s-1 bubbled with air containing 5.0 % CO2. These results suggest that optimization of light intensity and CO2 concentration can enhance the productivity of TAG and starch by C. debaryana NIES-2212.
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Affiliation(s)
- Masakazu Toyoshima
- Department of Life Sciences, Graduate School of Arts and Science, The University of Tokyo, Tokyo 153-8902, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo 102-0076, Japan.,Present address: Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Naoki Sato
- Department of Life Sciences, Graduate School of Arts and Science, The University of Tokyo, Tokyo 153-8902, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Tokyo 102-0076, Japan
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Wang X, Dong HP, Wei W, Balamurugan S, Yang WD, Liu JS, Li HY. Dual expression of plastidial GPAT1 and LPAT1 regulates triacylglycerol production and the fatty acid profile in Phaeodactylum tricornutum. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:318. [PMID: 30479663 PMCID: PMC6249879 DOI: 10.1186/s13068-018-1317-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 11/13/2018] [Indexed: 05/03/2023]
Abstract
BACKGROUND Metabolic engineering has emerged as a potential strategy for improving microalgal lipid content through targeted changes to lipid metabolic networks. However, the intricate nature of lipogenesis has impeded metabolic engineering. Therefore, it is very important to identify the crucial metabolic nodes and develop strategies to exploit multiple genes for transgenesis. In an attempt to unravel the microalgal triacylglycerol (TAG) pathway, we overexpressed two key lipogenic genes, glycerol-3-phosphate acyltransferase (GPAT1) and lysophosphatidic acid acyltransferase (LPAT1), in oleaginous Phaeodactylum tricornutum and determined their roles in microalgal lipogenesis. RESULTS Engineered P. tricornutum strains showed enhanced growth and photosynthetic efficiency compared with that of the wild-type during the growth phase of the cultivation period. However, both the cell types reached stationary phase on day 7. Overexpression of GPAT1 and LPAT1 increased the TAG content by 2.3-fold under nitrogen-replete conditions without compromising cell growth, and they also orchestrated the expression of other key genes involved in TAG synthesis. The transgenic expression of GPAT1 and LPAT1 influenced the expression of malic enzyme and glucose 6-phosphate dehydrogenase, which enhanced the levels of lipogenic NADPH in the transgenic lines. In addition, GPAT1 and LPAT1 preferred C16 over C18 at the sn-2 position of the glycerol backbone. CONCLUSION Overexpression of GPAT1 together with LPAT1 significantly enhanced lipid content without affecting growth and photosynthetic efficiency, and they orchestrated the expression of other key photosynthetic and lipogenic genes. The lipid profile for elevated fatty acid content (C16-CoA) demonstrated the involvement of the prokaryotic TAG pathway in marine diatoms. The results suggested that engineering dual metabolic nodes should be possible in microalgal lipid metabolism. This study also provides the first demonstration of the role of the prokaryotic TAG biosynthetic pathway in lipid overproduction and indicates that the fatty acid profile can be tailored to improve lipid production.
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Affiliation(s)
- Xiang Wang
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science, Jinan University, Guangzhou, 510632 China
| | - Hong-Po Dong
- School of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, 524088 China
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062 China
| | - Wei Wei
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science, Jinan University, Guangzhou, 510632 China
| | - Srinivasan Balamurugan
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science, Jinan University, Guangzhou, 510632 China
| | - Wei-Dong Yang
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science, Jinan University, Guangzhou, 510632 China
| | - Jie-Sheng Liu
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science, Jinan University, Guangzhou, 510632 China
| | - Hong-Ye Li
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science, Jinan University, Guangzhou, 510632 China
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