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Shene C, Asenjo JA, Chisti Y. Metabolic modelling and simulation of the light and dark metabolism of Chlamydomonas reinhardtii. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:1076-1088. [PMID: 30168220 DOI: 10.1111/tpj.14078] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 08/15/2018] [Accepted: 08/20/2018] [Indexed: 05/10/2023]
Abstract
A metabolic network model of the green microalga Chlamydomonas reinhardtii was used to characterize photoautotrophic and heterotrophic (i.e. growth on stored compounds) growth under light and dark, respectively. The metabolic network comprised 2514 reactions distributed among nine intracellular compartments and the extracellular space. The metabolic network included all the key biochemical pathways for synthesis and metabolism of starch and triacylglycerols (TAGs). Under light and nitrogen limitation, the model simulated the accumulation of the energy-rich compounds (TAGs and starch) in the cell. In the dark, the model could simulate cell growth and maintenance on stored compounds. The model-predicted consumption rates of storage compounds (starch or TAGs) to enable growth in the dark, were found to be greater than the rates of synthesis under light. This implied utilization of the storage compounds for cell maintenance in the dark. Under constant illumination, the simulations of cell growth and intracellular starch content agreed closely with independent experimental data. In other simulations, compared with the case without photorespiration, light uptake rate increased 1.04-fold when the ratio of the rates of oxygenation and carboxylation (Rubisco) was 0.1. Although extensive experimental work exists on culture and physiology of microalgae, it does not allow quantitative predictions of the influence of dark metabolism on the productivity of metabolites to be made. This limitation is overcome using the present model. A metabolic network model of Chlamydomonas reinhardtii is shown to simulate growth and synthesis of energy-rich compounds (triacylglycerols and starch) under light. The same model also simulates dark growth and maintenance through consumption of the stored energy-rich compounds.
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Affiliation(s)
- Carolina Shene
- Department of Chemical Engineering and Center of Food Biotechnology and Bioseparations, BIOREN, Universidad de La Frontera, Casilla 54-D, Temuco, Chile
- Centre for Biotechnology and Bioengineering (CeBiB), Universidad de La Frontera, Temuco, Chile
| | - Juan A Asenjo
- Centre for Biotechnology and Bioengineering (CeBiB), Department of Chemical Engineering and Biotechnology, Universidad de Chile, Beauchef 851, Santiago, Chile
| | - Yusuf Chisti
- School of Engineering, Massey University, Private Bag 11 222, Palmerston North, New Zealand
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Yang M, Meng Y, Chu Y, Fan Y, Cao X, Xue S, Chi Z. Triacylglycerol accumulates exclusively outside the chloroplast in short-term nitrogen-deprived Chlamydomonas reinhardtii. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:1478-1487. [PMID: 30266428 DOI: 10.1016/j.bbalip.2018.09.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 08/25/2018] [Accepted: 09/23/2018] [Indexed: 01/13/2023]
Abstract
In microalgae, triacylglycerol (TAG) biosynthesis occurs by parallel pathways involving both the chloroplast and endoplasmic reticulum. A better understanding of contribution of each pathway to TAG assembly facilitates enhanced TAG production via rational genetic engineering of microalgae. Here, using a UPLC-MS(/MS) coupled with TLC-GC-based lipidomic platform, the early response of the major glycerolipids to nitrogen stress was analyzed at both the cellular and chloroplastidic levels in the model green alga Chlamydomonas reinhardtii. Subcellular lipidomic analysis demonstrated that TAG was accumulated exclusively outside the chloroplast, and remained unaltered inside the chloroplast after 4 h of nitrogen starvation. This study ascertained the existence of the glycolipid, digalactosyldiacylglycerol (DGDG), outside the chloroplast and the betaine lipid, diacylglycerol-N,N,N-trimethylhomoserine (DGTS), inside the chloroplast. The newly synthesized DGDG and DGTS prominently increased at the extra-chloroplastidic compartments and served as the major precursors for TAG biosynthesis. In particular, DGDG contributed to the extra-chloroplastidic TAG assembly in form of diacylglycerol (DAG) and DGTS in form of acyl groups. The chloroplastidic membrane lipid, monogalactosyldiacylglycerol (MGDG), was proposed to primarily offer DAG for TAG formation outside the chloroplast. This study provides valuable insights into the subcellular glycerolipidomics and unveils the acyl flux into the extra-chloroplastidic TAG in microalgae.
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Affiliation(s)
- Miao Yang
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China; School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
| | - Yingying Meng
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yadong Chu
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
| | - Yan Fan
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Xupeng Cao
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
| | - Song Xue
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
| | - Zhanyou Chi
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
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Kong F, Romero IT, Warakanont J, Li-Beisson Y. Lipid catabolism in microalgae. THE NEW PHYTOLOGIST 2018; 218:1340-1348. [PMID: 29473650 DOI: 10.1111/nph.15047] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Accepted: 01/15/2018] [Indexed: 05/03/2023]
Abstract
Lipid degradation processes are important in microalgae because survival and growth of microalgal cells under fluctuating environmental conditions require permanent remodeling or turnover of membrane lipids as well as rapid mobilization of storage lipids. Lipid catabolism comprises two major spatially and temporarily separated steps, namely lipolysis, which releases fatty acids and head groups and is catalyzed by lipases at membranes or lipid droplets, and degradation of fatty acids to acetyl-CoA, which occurs in peroxisomes through the β-oxidation pathway in green microalgae, and can sometimes occur in mitochondria in some other algal species. Here we review the current knowledge on the enzymes and regulatory proteins involved in lipolysis and peroxisomal β-oxidation and highlight gaps in our understanding of lipid degradation pathways in microalgae. Metabolic use of acetyl-CoA products via glyoxylate cycle and gluconeogenesis is also reviewed. We then present the implication of various cellular processes such as vesicle trafficking, cell cycle and autophagy on lipid turnover. Finally, physiological roles and the manipulation of lipid catabolism for biotechnological applications in microalgae are discussed.
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Affiliation(s)
- Fantao Kong
- Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Aix Marseille Université, UMR7265, Institut de Biosciences et Biotechnologies Aix Marseille, 13108, Cadarache, France
| | - Ismael Torres Romero
- Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Aix Marseille Université, UMR7265, Institut de Biosciences et Biotechnologies Aix Marseille, 13108, Cadarache, France
| | - Jaruswan Warakanont
- Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Aix Marseille Université, UMR7265, Institut de Biosciences et Biotechnologies Aix Marseille, 13108, Cadarache, France
- Department of Botany, Faculty of Science, Kasetsart University, 50 Ngamwongwan Rd, Chatuchak, Bangkok, 10900, Thailand
| | - Yonghua Li-Beisson
- Commissariat à l'Energie Atomique et aux Energies Alternatives, CNRS, Aix Marseille Université, UMR7265, Institut de Biosciences et Biotechnologies Aix Marseille, 13108, Cadarache, France
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Smith RT, Gilmour DJ. The influence of exogenous organic carbon assimilation and photoperiod on the carbon and lipid metabolism of Chlamydomonas reinhardtii. ALGAL RES 2018. [DOI: 10.1016/j.algal.2018.01.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Sirikhachornkit A, Suttangkakul A, Vuttipongchaikij S, Juntawong P. De novo transcriptome analysis and gene expression profiling of an oleaginous microalga Scenedesmus acutus TISTR8540 during nitrogen deprivation-induced lipid accumulation. Sci Rep 2018; 8:3668. [PMID: 29487383 PMCID: PMC5829077 DOI: 10.1038/s41598-018-22080-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/16/2018] [Indexed: 11/30/2022] Open
Abstract
Nitrogen deprivation (-N) has been used as a technique to promote lipid accumulation in various microalgae. Scenedesmus acutus is a promising oleaginous green microalga that can be cultivated in organic wastewater for biodiesel production. Nevertheless, the molecular mechanisms controlling S. acutus lipid accumulation in response to -N remain unidentified. Physiological study determined that -N reduced cell growth and photosynthetic pigments. On the other hand, it promoted carbohydrate and neutral lipid accumulation. To find the mechanisms underlying lipid accumulation, we performed de novo transcriptome profiling of the non-model S. acutus in response to -N. The transcriptome analysis revealed that glycolysis and starch degradation were up-regulated; on the contrary, gluconeogenesis, photosynthesis, triacylglycerol (TAG) degradation and starch synthesis were down-regulated by -N. Under -N, the carbon flux was shifted toward fatty acid and TAG synthesis, and the down regulation of TAG lipase genes may contribute to TAG accumulation. A comparative analysis of the -N transcriptomes of oleaginous microalgae identified that the down-regulation of multiple lipase genes was a specific mechanism found only in the -N transcriptome of S. acutus. Our study unraveled the mechanisms controlling -N-induced lipid accumulation in S. acutus, and provided new perspectives for the genetic manipulation of biodiesel-producing microalgae.
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Affiliation(s)
- Anchalee Sirikhachornkit
- Special Research Unit in Microalgal Molecular Genetics and Functional genomics, Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Bangkok, Thailand
| | - Anongpat Suttangkakul
- Special Research Unit in Microalgal Molecular Genetics and Functional genomics, Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Bangkok, Thailand
| | - Supachai Vuttipongchaikij
- Special Research Unit in Microalgal Molecular Genetics and Functional genomics, Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Bangkok, Thailand
| | - Piyada Juntawong
- Special Research Unit in Microalgal Molecular Genetics and Functional genomics, Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand.
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Bangkok, Thailand.
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Kong F, Li-Beisson Y. Identification of Insertion Site by RESDA-PCR in Chlamydomonas Mutants Generated by AphVIII Random Insertional Mutagenesis. Bio Protoc 2018; 8:e2718. [PMID: 34179256 DOI: 10.21769/bioprotoc.2718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 01/16/2018] [Accepted: 01/18/2018] [Indexed: 11/02/2022] Open
Abstract
Chlamydomonas reinhardtii is frequently used as a model organism to study fundamental processes in photosynthesis, metabolism, and flagellar biology. Versatile tool boxes have been developed for this alga ( Fuhrmann et al., 1999 ; Schroda et al., 2000 ; Schroda, 2006). Among them, forward genetic approach has been intensively used, mostly because of the high efficiency in the generation of hundreds of thousands of mutants by random insertional mutagenesis and the haploid nature therefore phenotypic analysis can be done in the first generation ( Cagnon et al., 2013 ; Tunçay et al., 2013 ). A major bottleneck in the application of high throughput methods in a forward genetic approach is the identification of the genetic lesion(s) responsible for the observed phenotype. In this protocol, we describe in detail an improved version of the restriction enzyme site-directed amplification PCR (RESDA-PCR) originally reported in (González- Ballester et al., 2005 ). The improvement includes optimization of primer combination, the choice of DNA polymerase, optimization of PCR cycle parameters, and application of direct sequencing of the PCR products. These modifications make it easier to get specific PCR products as well as speeding up subcloning steps to obtain sequencing data faster.
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Affiliation(s)
- Fantao Kong
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France.,Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France.,Aix-Marseille Université, UMR7265, Marseille, France
| | - Yonghua Li-Beisson
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Environnementale et Biotechnologie, CEA Cadarache, Saint-Paul-lez-Durance, France.,Centre National de la Recherche Scientifique, UMR7265, Saint-Paul-lez-Durance, France.,Aix-Marseille Université, UMR7265, Marseille, France
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Jaeger D, Winkler A, Mussgnug JH, Kalinowski J, Goesmann A, Kruse O. Time-resolved transcriptome analysis and lipid pathway reconstruction of the oleaginous green microalga Monoraphidium neglectum reveal a model for triacylglycerol and lipid hyperaccumulation. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:197. [PMID: 28814974 PMCID: PMC5556983 DOI: 10.1186/s13068-017-0882-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 08/03/2017] [Indexed: 05/03/2023]
Abstract
BACKGROUND Oleaginous microalgae are promising production hosts for the sustainable generation of lipid-based bioproducts and as bioenergy carriers such as biodiesel. Transcriptomics of the lipid accumulation phase, triggered efficiently by nitrogen starvation, is a valuable approach for the identification of gene targets for metabolic engineering. RESULTS An explorative analysis of the detailed transcriptional response to different stages of nitrogen availability was performed in the oleaginous green alga Monoraphidium neglectum. Transcript data were correlated with metabolic data for cellular contents of starch and of different lipid fractions. A pronounced transcriptional down-regulation of photosynthesis became apparent in response to nitrogen starvation, whereas glucose catabolism was found to be up-regulated. An in-depth reconstruction and analysis of the pathways for glycerolipid, central carbon, and starch metabolism revealed that distinct transcriptional changes were generally found only for specific steps within a metabolic pathway. In addition to pathway analyses, the transcript data were also used to refine the current genome annotation. The transcriptome data were integrated into a database and complemented with data for other microalgae which were also subjected to nitrogen starvation. It is available at https://tdbmn.cebitec.uni-bielefeld.de. CONCLUSIONS Based on the transcriptional responses to different stages of nitrogen availability, a model for triacylglycerol and lipid hyperaccumulation is proposed, which involves transcriptional induction of thioesterases, differential regulation of lipases, and a re-routing of the central carbon metabolism. Over-expression of distinct thioesterases was identified to be a potential strategy to increase the oleaginous phenotype of M. neglectum, and furthermore specific lipases were identified as potential targets for future metabolic engineering approaches.
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Affiliation(s)
- Daniel Jaeger
- Algae Biotechnology and Bioenergy, Faculty of Biology, Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Anika Winkler
- Microbial Genomics and Biotechnology, Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Jan H. Mussgnug
- Algae Biotechnology and Bioenergy, Faculty of Biology, Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Jörn Kalinowski
- Microbial Genomics and Biotechnology, Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Alexander Goesmann
- Bioinformatics and Systems Biology, Justus-Liebig-Universität, 35392 Gießen, Germany
| | - Olaf Kruse
- Algae Biotechnology and Bioenergy, Faculty of Biology, Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
- Algae Biotechnology and Bioenergy, Faculty of Biology, Center for Biotechnology (CeBiTec), Bielefeld University, Universitaetsstrasse 27, 33615 Bielefeld, Germany
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