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Zhang L, Yuan Q, Hu C, Sun X, Gong Y, Xu N. Characterization of monogalactosyldiacylglycerol synthases in Gracilariopsis lemaneiformis and their potential roles in the fading of the thallus. JOURNAL OF PHYCOLOGY 2023; 59:1258-1271. [PMID: 37688517 DOI: 10.1111/jpy.13384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 06/24/2023] [Accepted: 06/26/2023] [Indexed: 09/11/2023]
Abstract
Membrane lipids play essential roles in regulating physiological properties in higher plants and algae. Monogalactosyldiacylglycerol (MGDG) is a major thylakoid membrane lipid, and it is an important source of polyunsaturated fatty acids for cells, plays a key role in the biogenesis of plastids, and maintains the function of the photosynthetic machinery. Several studies have indicated that the knockdown of MGDG synthase results in membrane lipid remodeling, albino seedlings, and changes in photosynthetic performance. However, the effects of MGDG synthase (MGD) inhibitors on lipids in macroalgae have not yet been clarified. Here, we characterized the effects of MGD inhibitors (ortho-phenanthroline and N-ethylmaleimide) on the composition of the fatty acids observed in MGDG and digalactosyldiacylglycerol (DGDG) in Gracilariopsis lemaneiformis using electrospray ionization-mass spectrometry. The most abundant MGDG species contained 16:0/18:1 (sn-1/sn-2) fatty acids, and the most dominant DGDG species contained 20:5/16:0 (sn-1/sn-2) fatty acids. Measurements of photosynthetic pigments and photosynthetic parameters revealed that photosynthesis of G. lemaneiformis was impaired. Principal component analysis and Spearman's correlation analysis revealed interactions between specific MGDG structural composition patterns and key metabolites involved in photosynthesis, indicating that 20:4/16:0 (sn-1/sn-2) MGDG and 16:0/18:1 (sn-1/sn-2) MGDG affect the structure and function of phycobilisomes and thus the color of G. lemaneiformis. Three genes (GlMGD1, GlMGD2, and GlMGD3) were cloned and identified. The addition of N-ethylmaleimide to G. lemaneiformis did not affect the abundance of GlMGD mRNA, and the abundance of transcripts was significantly decreased by ortho-phenanthroline.
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Affiliation(s)
- Li Zhang
- School of Marine Sciences, Ningbo University, Zhejiang, China
| | - Quan Yuan
- Institute of Plant Virology, Ningbo University, Zhejiang, China
| | - Chaoyang Hu
- School of Marine Sciences, Ningbo University, Zhejiang, China
| | - Xue Sun
- School of Marine Sciences, Ningbo University, Zhejiang, China
| | - Yifu Gong
- School of Marine Sciences, Ningbo University, Zhejiang, China
| | - Nianjun Xu
- School of Marine Sciences, Ningbo University, Zhejiang, China
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2
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Negi J, Obata T, Nishimura S, Song B, Yamagaki S, Ono Y, Okabe M, Hoshino N, Fukatsu K, Tabata R, Yamaguchi K, Shigenobu S, Yamada M, Hasebe M, Sawa S, Kinoshita T, Nishida I, Iba K. PECT1, a rate-limiting enzyme in phosphatidylethanolamine biosynthesis, is involved in the regulation of stomatal movement in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023. [PMID: 37058128 DOI: 10.1111/tpj.16245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/27/2023] [Accepted: 04/10/2023] [Indexed: 05/16/2023]
Abstract
An Arabidopsis mutant displaying impaired stomatal responses to CO2 , cdi4, was isolated by a leaf thermal imaging screening. The mutated gene PECT1 encodes CTP:phosphorylethanolamine cytidylyltransferase. The cdi4 exhibited a decrease in phosphatidylethanolamine levels and a defect in light-induced stomatal opening as well as low-CO2 -induced stomatal opening. We created RNAi lines in which PECT1 was specifically repressed in guard cells. These lines are impaired in their stomatal responses to low-CO2 concentrations or light. Fungal toxin fusicoccin (FC) promotes stomatal opening by activating plasma membrane H+ -ATPases in guard cells via phosphorylation. Arabidopsis H+ -ATPase1 (AHA1) has been reported to be highly expressed in guard cells, and its activation by FC induces stomatal opening. The cdi4 and PECT1 RNAi lines displayed a reduced stomatal opening response to FC. However, similar to in the wild-type, cdi4 maintained normal levels of phosphorylation and activation of the stomatal H+ -ATPases after FC treatment. Furthermore, the cdi4 displayed normal localization of GFP-AHA1 fusion protein and normal levels of AHA1 transcripts. Based on these results, we discuss how PECT1 could regulate CO2 - and light-induced stomatal movements in guard cells in a manner that is independent and downstream of the activation of H+ -ATPases. [Correction added on 15 May 2023, after first online publication: The third sentence is revised in this version.].
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Affiliation(s)
- Juntaro Negi
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Tomoki Obata
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Sakura Nishimura
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Boseok Song
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Sho Yamagaki
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Yuhei Ono
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Makoto Okabe
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 812-8581, Japan
| | - Natsumi Hoshino
- Graduate School of Science and Engineering, Saitama University, 338-8570, Saitama, Japan
| | - Kohei Fukatsu
- Graduate School of Science and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya, 464-8602, Japan
| | - Ryo Tabata
- International Research Center for Agricultural and Environmental Biology, Kumamoto University, 2-39-1, Kumamoto, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | | | | | - Masashi Yamada
- Department of Biology and HHMI, Duke University, Durham, North Carolina, 27710, USA
| | - Mitsuyasu Hasebe
- National Institute for Basic Biology, Okazaki, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (Graduate University for Advanced Studies), Okazaki, 444-8585, Japan
| | - Shinichiro Sawa
- International Research Center for Agricultural and Environmental Biology, Kumamoto University, 2-39-1, Kumamoto, Japan
| | - Toshinori Kinoshita
- Graduate School of Science and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya, 464-8602, Japan
| | - Ikuo Nishida
- Graduate School of Science and Engineering, Saitama University, 338-8570, Saitama, Japan
| | - Koh Iba
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 812-8581, Japan
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3
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Plastid Phosphatidylglycerol Homeostasis Is Required for Plant Growth and Metabolism in Arabidopsis thaliana. Metabolites 2023; 13:metabo13030318. [PMID: 36984758 PMCID: PMC10058643 DOI: 10.3390/metabo13030318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/14/2023] [Accepted: 02/14/2023] [Indexed: 02/24/2023] Open
Abstract
A unique feature of plastid phosphatidylglycerol (PG) is a trans-double bond specifically at the sn-2 position of 16C fatty acid (16:1t- PG), which is catalyzed by FATTY ACID DESATURASE 4 (FAD4). To offer additional insights about the in vivo roles of FAD4 and its product 16:1t-PG, FAD4 overexpression lines (OX-FAD4s) were generated in Arabidopsis thaliana Columbia ecotype. When grown under continuous light condition, the fad4-2 and OX-FAD4s plants exhibited higher growth rates compared to WT control. Total lipids were isolated from Col, fad4-2, and OX-FAD4_2 plants, and polar lipids quantified by lipidomic profiling. We found that disrupting FAD4 expression altered prokaryotic and eukaryotic PG content and composition. Prokaryotic and eukaryotic monogalactosyl diacylglycerol (MGDG) was up-regulated in OX-FAD4 plants but not in fad4-2 mutant. We propose that 16:1t-PG homeostasis in plastid envelope membranes may coordinate plant growth and stress response by restricting photoassimilate export from the chloroplast.
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Jiang L, Geng D, Zhi F, Li Z, Yang Y, Wang Y, Shen X, Liu X, Yang Y, Xu Y, Tang Y, Du R, Ma F, Guan Q, Zhang J. A genome-wide association study provides insights into fatty acid synthesis and metabolism in Malus fruits. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:7467-7476. [PMID: 36112134 DOI: 10.1093/jxb/erac372] [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: 01/30/2022] [Accepted: 09/15/2022] [Indexed: 06/15/2023]
Abstract
As a precursor of aromatic compounds, fatty acids play important roles in apple fruit quality; however, the genetic and molecular basis underlying fatty acid synthesis and metabolism is largely unknown. In this study, we conducted a genome-wide association study (GWAS) of seven fatty acids using genomic data of 149 Malus accessions and identified 232 significant signals (-log10P>5) associated with 99 genes from GWAS of four fatty acids across 2 years. Among these, a significant GWAS signal associated with linoleic acid was identified in the transcriptional regulator SUPERMAN-like (SUP) MD13G1209600 at chromosome 13 of M. × domestica. Transient overexpression of MdSUP increased the contents of linoleic and linolenic acids and of three aromatic components in the fruit. Our study provides genetic and molecular information for improving the flavor and nutritional value of apple.
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Affiliation(s)
- Lijuan Jiang
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Dali Geng
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Fang Zhi
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Zhongxing Li
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Yusen Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Yunlong Wang
- College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Xiaoxia Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Xiuyun Liu
- Institute of Vocational Technology, Shanghai 200000, China
| | - Yanqing Yang
- College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Yange Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Yanlong Tang
- College of Economics and Management, Northwest A&F University, Yangling 712100, China
| | - Rui Du
- College of Innovation and Experiment, Northwest A&F University, Yangling 712100, China
| | - Fengwang Ma
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Qingmei Guan
- State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Jing Zhang
- College of Horticulture, Northwest A&F University, Yangling 712100, China
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Bolik S, Albrieux C, Schneck E, Demé B, Jouhet J. Sulfoquinovosyldiacylglycerol and phosphatidylglycerol bilayers share biophysical properties and are good mutual substitutes in photosynthetic membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184037. [PMID: 36041508 DOI: 10.1016/j.bbamem.2022.184037] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 06/22/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Affiliation(s)
- Stéphanie Bolik
- Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG, LPCV, 38000 Grenoble, France; Institut Laue-Langevin, 38000 Grenoble, France
| | - Catherine Albrieux
- Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG, LPCV, 38000 Grenoble, France
| | - Emanuel Schneck
- Institute for Condensed Matter Physics, TU Darmstadt, 64289 Darmstadt, Germany
| | - Bruno Demé
- Institut Laue-Langevin, 38000 Grenoble, France.
| | - Juliette Jouhet
- Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG, LPCV, 38000 Grenoble, France.
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6
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Hao X, Chen W, Amato A, Jouhet J, Maréchal E, Moog D, Hu H, Jin H, You L, Huang F, Moosburner M, Allen AE, Gong Y. Multiplexed CRISPR/Cas9 editing of the long-chain acyl-CoA synthetase family in the diatom Phaeodactylum tricornutum reveals that mitochondrial ptACSL3 is involved in the synthesis of storage lipids. THE NEW PHYTOLOGIST 2022; 233:1797-1812. [PMID: 34882804 DOI: 10.1111/nph.17911] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 12/01/2021] [Indexed: 06/13/2023]
Abstract
Long-chain acyl-CoA synthetases (LACS) play diverse and fundamentally important roles in lipid metabolism. While their functions have been well established in bacteria, yeast and plants, the mechanisms by which LACS isozymes regulate lipid metabolism in unicellular oil-producing microalgae, including the diatom Phaeodactylum tricornutum, remain largely unknown. In P. tricornutum, a family of five genes (ptACSL1-ptACSL5) encodes LACS activities. We generated single lacs knockout/knockdown mutants using multiplexed CRISPR/Cas9 method, and determined their substrate specificities towards different fatty acids (FAs) and subcellular localisations. ptACSL3 is localised in the mitochondria and its disruption led to compromised growth and reduced triacylglycerol (TAG) content when cells were bubbled with air. The ptACSL3 mutants showed altered FA profiles in two galactoglycerolipids and phosphatidylcholine (PC) with significantly reduced distribution of 16:0 and 16:1. ptACSL5 is localised in the peroxisome and its knockdown resulted in reduced growth rate and altered molecular species of PC and TAG, indicating a role in controlling the composition of acyl-CoAs for lipid synthesis. Our work demonstrates the potential of generating gene knockout mutants with the mutation of large fragment deletion using multiplexed CRISPR/Cas9 and provides insight into the functions of LACS isozymes in lipid metabolism in the oleaginous microalgae.
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Affiliation(s)
- Xiahui Hao
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
| | - Wenchao Chen
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
| | - Alberto Amato
- Laboratoire de Physiologie Cellulaire et Végétale, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut National de la Recherche Agronomique, Université Grenoble Alpes, UMR 5168, Grenoble, F-38041, France
| | - Juliette Jouhet
- Laboratoire de Physiologie Cellulaire et Végétale, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut National de la Recherche Agronomique, Université Grenoble Alpes, UMR 5168, Grenoble, F-38041, France
| | - Eric Maréchal
- Laboratoire de Physiologie Cellulaire et Végétale, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Institut National de la Recherche Agronomique, Université Grenoble Alpes, UMR 5168, Grenoble, F-38041, France
| | - Daniel Moog
- Laboratory for Cell Biology, Philipps-University Marburg, Marburg, D-35032, Germany
| | - Hanhua Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Hu Jin
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Lingjie You
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
| | - Fenghong Huang
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
| | - Mark Moosburner
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, 92093, USA
- J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, CA, 92037, USA
| | - Andrew E Allen
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, 92093, USA
- J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, CA, 92037, USA
| | - Yangmin Gong
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
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Simpson JP, Wunderlich C, Li X, Svedin E, Dilkes B, Chapple C. Metabolic source isotopic pair labeling and genome-wide association are complementary tools for the identification of metabolite-gene associations in plants. THE PLANT CELL 2021; 33:492-510. [PMID: 33955498 PMCID: PMC8136897 DOI: 10.1093/plcell/koaa046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 12/21/2020] [Indexed: 05/02/2023]
Abstract
The optimal extraction of information from untargeted metabolomics analyses is a continuing challenge. Here, we describe an approach that combines stable isotope labeling, liquid chromatography- mass spectrometry (LC-MS), and a computational pipeline to automatically identify metabolites produced from a selected metabolic precursor. We identified the subset of the soluble metabolome generated from phenylalanine (Phe) in Arabidopsis thaliana, which we refer to as the Phe-derived metabolome (FDM) In addition to identifying Phe-derived metabolites present in a single wild-type reference accession, the FDM was established in nine enzymatic and regulatory mutants in the phenylpropanoid pathway. To identify genes associated with variation in Phe-derived metabolites in Arabidopsis, MS features collected by untargeted metabolite profiling of an Arabidopsis diversity panel were retrospectively annotated to the FDM and natural genetic variants responsible for differences in accumulation of FDM features were identified by genome-wide association. Large differences in Phe-derived metabolite accumulation and presence/absence variation of abundant metabolites were observed in the nine mutants as well as between accessions from the diversity panel. Many Phe-derived metabolites that accumulated in mutants also accumulated in non-Col-0 accessions and was associated to genes with known or suspected functions in the phenylpropanoid pathway as well as genes with no known functions. Overall, we show that cataloguing a biochemical pathway's products through isotopic labeling across genetic variants can substantially contribute to the identification of metabolites and genes associated with their biosynthesis.
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Affiliation(s)
- Jeffrey P Simpson
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue University Center for Plant Biology, West Lafayette, IN 47907, USA
| | - Cole Wunderlich
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Xu Li
- Plants for Human Health Institute, North Carolina State University, Kannapolis, NC 28081, USA
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | | | - Brian Dilkes
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue University Center for Plant Biology, West Lafayette, IN 47907, USA
| | - Clint Chapple
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
- Purdue University Center for Plant Biology, West Lafayette, IN 47907, USA
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8
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Obata T, Kobayashi K, Tadakuma R, Akasaka T, Iba K, Negi J. The Endoplasmic Reticulum Pathway for Membrane Lipid Synthesis Has a Significant Contribution toward Shoot Removal-Induced Root Chloroplast Development in Arabidopsis. ACTA ACUST UNITED AC 2021; 62:494-501. [DOI: 10.1093/pcp/pcab009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/14/2021] [Indexed: 12/25/2022]
Abstract
Abstract
Chloroplast lipids are synthesized via two distinct pathways: the plastidic pathway and endoplasmic reticulum (ER) pathway. We previously reported that the contribution of the two pathways toward chloroplast development is different between mesophyll cells and guard cells in Arabidopsis leaf tissues and that the ER pathway plays a major role in guard cell chloroplast development. However, little is known about the contribution of the two pathways toward chloroplast development in other tissue cells, and in this study, we focused on root cells. Chloroplast development is normally repressed in roots but can be induced when the roots are detached from the shoots (root greening). We found that, similar to guard cells, root cells exhibit a higher proportion of glycolipid from the ER pathway. Root greening was repressed in the gles1 mutant, which has a defect in ER-to-plastid lipid transportation via the ER pathway, while normal root greening was observed in the ats1 mutant, whose plastidic pathway is blocked. Lipid analysis revealed that the gles1 mutation caused drastic decrease in the ER-derived glycolipids in roots. Furthermore, the gles1 detached roots showed smaller chloroplasts containing less starch than WT. These results suggest that the ER pathway has a significant contribution toward chloroplast development in the root cells.
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Affiliation(s)
- Tomoki Obata
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 819-0395 Japan
| | - Koichi Kobayashi
- Faculty of Liberal Arts and Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai Osaka, 599-8531 Japan
| | - Ryosuke Tadakuma
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 819-0395 Japan
| | - Taiki Akasaka
- Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395 Japan
| | - Koh Iba
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 819-0395 Japan
| | - Juntaro Negi
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 819-0395 Japan
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9
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Pfaff J, Denton AK, Usadel B, Pfaff C. Phosphate starvation causes different stress responses in the lipid metabolism of tomato leaves and roots. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158763. [DOI: 10.1016/j.bbalip.2020.158763] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 06/15/2020] [Accepted: 07/03/2020] [Indexed: 12/17/2022]
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10
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Sahaka M, Amara S, Wattanakul J, Gedi MA, Aldai N, Parsiegla G, Lecomte J, Christeller JT, Gray D, Gontero B, Villeneuve P, Carrière F. The digestion of galactolipids and its ubiquitous function in Nature for the uptake of the essential α-linolenic acid. Food Funct 2020; 11:6710-6744. [PMID: 32687132 DOI: 10.1039/d0fo01040e] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Galactolipids, mainly monogalactosyl diglycerides and digalactosyl diglycerides are the main lipids found in the membranes of plants, algae and photosynthetic microorganisms like microalgae and cyanobacteria. As such, they are the main lipids present at the surface of earth. They may represent up to 80% of the fatty acid stocks, including a large proportion of polyunsaturated fatty acids mainly α-linolenic acid (ALA). Nevertheless, the interest in these lipids for nutrition and other applications remains overlooked, probably because they are dispersed in the biomass and are not as easy to extract as vegetable oils from oleaginous fruit and oil seeds. Another reason is that galactolipids only represent a small fraction of the acylglycerolipids present in modern human diet. In herbivores such as horses, fish and folivorous insects, galactolipids may however represent the main source of dietary fatty acids due to their dietary habits and digestion physiology. The development of galactolipase assays has led to the identification and characterization of the enzymes involved in the digestion of galactolipids in the gastrointestinal tract, as well as by microorganisms. Pancreatic lipase-related protein 2 (PLRP2) has been identified as an important factor of galactolipid digestion in humans, together with pancreatic carboxyl ester hydrolase (CEH). The levels of PLRP2 are particularly high in monogastric herbivores thus highlighting the peculiar role of PLRP2 in the digestion of plant lipids. Similarly, pancreatic lipase homologs are found to be expressed in the midgut of folivorous insects, in which a high galactolipase activity can be measured. In fish, however, CEH is the main galactolipase involved. This review discusses the origins and fatty acid composition of galactolipids and the physiological contribution of galactolipid digestion in various species. This overlooked aspect of lipid digestion ensures not only the intake of ALA from its main natural source, but also the main lipid source of energy for growth of some herbivorous species.
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Affiliation(s)
- Moulay Sahaka
- Aix Marseille Univ, CNRS, UMR7281 Bioénergétique et Ingénierie des Protéines, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
| | - Sawsan Amara
- Lipolytech, Zone Luminy Biotech, 163 avenue de Luminy, 13288 Marseille Cedex 09, France
| | - Jutarat Wattanakul
- Division of Food, Nutrition and Dietetics, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK
| | - Mohamed A Gedi
- Division of Food, Nutrition and Dietetics, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK
| | - Noelia Aldai
- Lactiker Research Group, Department of Pharmacy & Food Sciences, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
| | - Goetz Parsiegla
- Aix Marseille Univ, CNRS, UMR7281 Bioénergétique et Ingénierie des Protéines, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
| | | | - John T Christeller
- The New Zealand Institute for Plant and Food Research Ltd (Plant & Food Research), Palmerston North Research Centre, Palmerston North, New Zealand
| | - David Gray
- Division of Food, Nutrition and Dietetics, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK
| | - Brigitte Gontero
- Aix Marseille Univ, CNRS, UMR7281 Bioénergétique et Ingénierie des Protéines, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
| | | | - Frédéric Carrière
- Aix Marseille Univ, CNRS, UMR7281 Bioénergétique et Ingénierie des Protéines, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
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11
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Study of Synthesis Pathways of the Essential Polyunsaturated Fatty Acid 20:5n-3 in the Diatom Chaetoceros Muelleri Using 13C-Isotope Labeling. Biomolecules 2020; 10:biom10050797. [PMID: 32455747 PMCID: PMC7277837 DOI: 10.3390/biom10050797] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/15/2020] [Accepted: 05/19/2020] [Indexed: 12/12/2022] Open
Abstract
The present study sought to characterize the synthesis pathways producing the essential polyunsaturated fatty acid (PUFA) 20:5n-3 (EPA). For this, the incorporation of 13C was experimentally monitored into 10 fatty acids (FA) during the growth of the diatom Chaetoceros muelleri for 24 h. Chaetoceros muelleri preferentially and quickly incorporated 13C into C18 PUFAs such as 18:2n-6 and 18:3n-6 as well as 16:0 and 16:1n-7, which were thus highly 13C-enriched. During the experiment, 20:5n-3 and 16:3n-4 were among the least-enriched fatty acids. The calculation of the enrichment percentage ratio of a fatty acid B over its suspected precursor A allowed us to suggest that the diatom produced 20:5n-3 (EPA) by a combination between the n-3 (via 18:4n-3) and n-6 (via 18:3n-6 and 20:4n-6) synthesis pathways as well as the alternative ω-3 desaturase pathway (via 20:4n-6). In addition, as FA from polar lipids were generally more enriched in 13C than FA from neutral lipids, particularly for 18:1n-9, 18:2n-6 and 18:3n-6, the existence of acyl-editing mechanisms and connectivity between polar and neutral lipid fatty acid pools were also hypothesized. Because 16:3n-4 and 20:5n-3 presented the same concentration and enrichment dynamics, a structural and metabolic link was proposed between these two PUFAs in C. muelleri.
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12
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Mori N, Moriyama T, Sato N. Uncommon properties of lipid biosynthesis of isolated plastids in the unicellular red alga Cyanidioschyzon merolae. FEBS Open Bio 2018; 9:114-128. [PMID: 30652079 PMCID: PMC6325583 DOI: 10.1002/2211-5463.12551] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 11/02/2018] [Accepted: 11/05/2018] [Indexed: 12/22/2022] Open
Abstract
Red algae are a large group of photosynthetic eukaryotes that diverged from green algae over one billion years ago, and have various traits distinct from those of both green algae and land plants. Although most red algae are marine species (both unicellular and macrophytic), the Cyanidiales class of red algae includes unicellular species which live in hot springs, such as Cyanidioschyzon merolae, which is a model species for biochemical and molecular biological studies. Lipid metabolism in red algae has previously been studied in intact cells. Here, we present the results of radiolabeling and stable isotope labeling experiments in intact plastids isolated from the unicellular red alga C. merolae. We focused on two uncommon features: First, the galactose moiety of monogalactosyldiacylglycerol was efficiently labeled with bicarbonate, indicating that an unknown pathway for providing UDP-galactose exists within the plastid. Second, saturated fatty acids, namely, palmitic and stearic acids, were the sole products of fatty acid synthesis in the plastid, and they were efficiently exported. This finding suggests that the endoplasmic reticulum is the sole site of desaturation. We present a general principle of red algal lipid biosynthesis, namely, 'indigenous C18 fatty acids are neither desaturated nor directly utilized within the plastid'. We believe that this is valid in both C. merolae lacking polyunsaturated fatty acids and marine red algae with a high content of arachidonic and eicosapentaenoic acids.
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Affiliation(s)
- Natsumi Mori
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
| | - Takashi Moriyama
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
| | - Naoki Sato
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
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13
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de Jaeger L, Springer J, Wolbert EJH, Martens DE, Eggink G, Wijffels RH. Gene silencing of stearoyl-ACP desaturase enhances the stearic acid content in Chlamydomonas reinhardtii. BIORESOURCE TECHNOLOGY 2017; 245:1616-1626. [PMID: 28693951 DOI: 10.1016/j.biortech.2017.06.128] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 05/18/2023]
Abstract
In this study, stearoyl-ACP desaturase (SAD), the enzyme that converts stearic acid into oleic acid, is silenced by artificial microRNA in the green microalga Chlamydomonas reinhardtii. Two different constructs, which target different positions on the mRNA of stearoyl-ACP desaturase, were tested. The mRNA levels for SAD were reduced after the silencing construct was induced. In one of the strains, the reduction in SAD mRNA resulted in a doubling of the stearic acid content in triacylglycerol molecules, which shows that stearic acid production in microalgae is possible.
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Affiliation(s)
- L de Jaeger
- Bioprocess Engineering and AlgaePARC, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, The Netherlands; Food and Biobased Research and AlgaePARC, Wageningen University and Research Centre, PO Box 17, 6700 AA Wageningen, The Netherlands
| | - J Springer
- Food and Biobased Research and AlgaePARC, Wageningen University and Research Centre, PO Box 17, 6700 AA Wageningen, The Netherlands
| | - E J H Wolbert
- Food and Biobased Research and AlgaePARC, Wageningen University and Research Centre, PO Box 17, 6700 AA Wageningen, The Netherlands
| | - D E Martens
- Bioprocess Engineering and AlgaePARC, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, The Netherlands
| | - G Eggink
- Bioprocess Engineering and AlgaePARC, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, The Netherlands; Food and Biobased Research and AlgaePARC, Wageningen University and Research Centre, PO Box 17, 6700 AA Wageningen, The Netherlands
| | - R H Wijffels
- Bioprocess Engineering and AlgaePARC, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, The Netherlands; Faculty of Biosciences and Aquaculture, University of Nordland, N-8049 Bodø, Norway.
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14
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Dolch LJ, Rak C, Perin G, Tourcier G, Broughton R, Leterrier M, Morosinotto T, Tellier F, Faure JD, Falconet D, Jouhet J, Sayanova O, Beaudoin F, Maréchal E. A Palmitic Acid Elongase Affects Eicosapentaenoic Acid and Plastidial Monogalactosyldiacylglycerol Levels in Nannochloropsis. PLANT PHYSIOLOGY 2017; 173:742-759. [PMID: 27895203 PMCID: PMC5210741 DOI: 10.1104/pp.16.01420] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 11/24/2016] [Indexed: 05/03/2023]
Abstract
Nannochloropsis species are oleaginous eukaryotes containing a plastid limited by four membranes, deriving from a secondary endosymbiosis. In Nannochloropsis, thylakoid lipids, including monogalactosyldiacylglycerol (MGDG), are enriched in eicosapentaenoic acid (EPA). The need for EPA in MGDG is not understood. Fatty acids are de novo synthesized in the stroma, then converted into very-long-chain polyunsaturated fatty acids (FAs) at the endoplasmic reticulum (ER). The production of MGDG relies therefore on an EPA supply from the ER to the plastid, following an unknown process. We identified seven elongases and five desaturases possibly involved in EPA production in Nannochloropsis gaditana Among the six heterokont-specific saturated FA elongases possibly acting upstream in this pathway, we characterized the highly expressed isoform Δ0-ELO1 Heterologous expression in yeast (Saccharomyces cerevisiae) showed that NgΔ0-ELO1 could elongate palmitic acid. Nannochloropsis Δ0-elo1 mutants exhibited a reduced EPA level and a specific decrease in MGDG In NgΔ0-elo1 lines, the impairment of photosynthesis is consistent with a role of EPA-rich MGDG in nonphotochemical quenching control, possibly providing an appropriate MGDG platform for the xanthophyll cycle. Concomitantly with MGDG decrease, the level of triacylglycerol (TAG) containing medium chain FAs increased. In Nannochloropsis, part of EPA used for MGDG production is therefore biosynthesized by a channeled process initiated at the elongation step of palmitic acid by Δ0-ELO1, thus acting as a committing enzyme for galactolipid production. Based on the MGDG/TAG balance controlled by Δ0-ELO1, this study also provides novel prospects for the engineering of oleaginous microalgae for biotechnological applications.
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Affiliation(s)
- Lina-Juana Dolch
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.)
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.);
| | - Camille Rak
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.)
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.);
| | - Giorgio Perin
- Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.)
- Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.);
| | - Guillaume Tourcier
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.)
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.);
| | - Richard Broughton
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.)
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.);
| | - Marina Leterrier
- Fermentalg, 4 Rue Rivière, 33500, Libourne, France (M.L.); and
- Fermentalg, 4 Rue Rivière, 33500, Libourne, France (M.L.); and
| | - Tomas Morosinotto
- Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.)
- Padua Algae Research Laboratory, Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy (G.P., T.M.);
| | - Frédérique Tellier
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.)
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.)
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.)
| | - Jean-Denis Faure
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.)
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France (J.-D.F.)
| | - Denis Falconet
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.)
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.);
| | - Juliette Jouhet
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.)
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.);
| | - Olga Sayanova
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.)
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.);
| | - Frédéric Beaudoin
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.)
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom (R.B., O.S., F.B.);
| | - Eric Maréchal
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.)
- Laboratoire de Physiologie Cellulaire et Végétale, Unité mixte de recherche 5168 CNRS - CEA - Université Grenoble 1, Institut de Recherche en Sciences et Technologies pour le Vivant, CEA Grenoble, 17 rue des Martyrs, 38054, Grenoble Cedex 9, France (L.-J.D., C.R., G.T., D.F., J.J., E.M.);
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15
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Lung SC, Chye ML. Deciphering the roles of acyl-CoA-binding proteins in plant cells. PROTOPLASMA 2016; 253:1177-95. [PMID: 26340904 DOI: 10.1007/s00709-015-0882-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 08/21/2015] [Indexed: 05/18/2023]
Abstract
Lipid trafficking is vital for metabolite exchange and signal communications between organelles and endomembranes. Acyl-CoA-binding proteins (ACBPs) are involved in the intracellular transport, protection, and pool formation of acyl-CoA esters, which are important intermediates and regulators in lipid metabolism and cellular signaling. In this review, we highlight recent advances in our understanding of plant ACBP families from a cellular and developmental perspective. Plant ACBPs have been extensively studied in Arabidopsis thaliana (a dicot) and to a lesser extent in Oryza sativa (a monocot). Thus far, they have been detected in the plasma membrane, vesicles, endoplasmic reticulum, Golgi apparatus, apoplast, cytosol, nuclear periphery, and peroxisomes. In combination with biochemical and molecular genetic tools, the widespread subcellular distribution of respective ACBP members has been explicitly linked to their functions in lipid metabolism during development and in response to stresses. At the cellular level, strong expression of specific ACBP homologs in specialized cells, such as embryos, stem epidermis, guard cells, male gametophytes, and phloem sap, is of relevance to their corresponding distinct roles in organ development and stress responses. Other interesting patterns in their subcellular localization and spatial expression that prompt new directions in future investigations are discussed.
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Affiliation(s)
- Shiu-Cheung Lung
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Mee-Len Chye
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
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16
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Allen DK. Assessing compartmentalized flux in lipid metabolism with isotopes. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1226-1242. [PMID: 27003250 DOI: 10.1016/j.bbalip.2016.03.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 03/13/2016] [Accepted: 03/14/2016] [Indexed: 12/28/2022]
Abstract
Metabolism in plants takes place across multiple cell types and within distinct organelles. The distributions equate to spatial heterogeneity; though the limited means to experimentally assess metabolism frequently involve homogenizing tissues and mixing metabolites from different locations. Most current isotope investigations of metabolism therefore lack the ability to resolve spatially distinct events. Recognition of this limitation has resulted in inspired efforts to advance metabolic flux analysis and isotopic labeling techniques. Though a number of these efforts have been applied to studies in central metabolism; recent advances in instrumentation and techniques present an untapped opportunity to make similar progress in lipid metabolism where the use of stable isotopes has been more limited. These efforts will benefit from sophisticated radiolabeling reports that continue to enrich our knowledge on lipid biosynthetic pathways and provide some direction for stable isotope experimental design and extension of MFA. Evidence for this assertion is presented through the review of several elegant stable isotope studies and by taking stock of what has been learned from radioisotope investigations when spatial aspects of metabolism were considered. The studies emphasize that glycerolipid production occurs across several locations with assembly of lipids in the ER or plastid, fatty acid biosynthesis occurring in the plastid, and the generation of acetyl-CoA and glycerol-3-phosphate taking place at multiple sites. Considering metabolism in this context underscores the cellular and subcellular organization that is important to enhanced production of glycerolipids in plants. An attempt is made to unify salient features from a number of reports into a diagrammatic model of lipid metabolism and propose where stable isotope labeling experiments and further flux analysis may help address questions in the field. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Doug K Allen
- United States Department of Agriculture, Agricultural Research Service, 975 North Warson Road, St. Louis, MO 63132, United States; Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, United States.
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17
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Abstract
Acyl-CoA-binding proteins (ACBPs) play a pivotal role in fatty acid metabolism because they can transport medium- and long-chain acyl-CoA esters. In eukaryotic cells, ACBPs are involved in intracellular trafficking of acyl-CoA esters and formation of a cytosolic acyl-CoA pool. In addition to these ubiquitous functions, more specific non-redundant roles of plant ACBP subclasses are implicated by the existence of multigene families with variable molecular masses, ligand specificities, functional domains (e.g. protein-protein interaction domains), subcellular locations and gene expression patterns. In this chapter, recent progress in the characterization of ACBPs from the model dicot plant, Arabidopsis thaliana, and the model monocot, Oryza sativa, and their emerging roles in plant growth and development are discussed. The functional significance of respective members of the plant ACBP families in various developmental and physiological processes such as seed development and germination, stem cuticle formation, pollen development, leaf senescence, peroxisomal fatty acid β-oxidation and phloem-mediated lipid transport is highlighted.
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Affiliation(s)
- Shiu-Cheung Lung
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Mee-Len Chye
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
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18
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Lung SC, Chye ML. The binding versatility of plant acyl-CoA-binding proteins and their significance in lipid metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:1409-1421. [PMID: 26747650 DOI: 10.1016/j.bbalip.2015.12.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 12/28/2015] [Accepted: 12/29/2015] [Indexed: 11/18/2022]
Abstract
Acyl-CoA esters are the activated form of fatty acids and play important roles in lipid metabolism and the regulation of cell functions. They are bound and transported by nonenzymic proteins such as the acyl-CoA-binding proteins (ACBPs). Although plant ACBPs were so named by virtue of amino acid homology to existing yeast and mammalian counterparts, recent studies revealed that ligand specificities of plant ACBPs are not restricted to acyl-CoA esters. Arabidopsis and rice ACBPs also interact with phospholipids, and their affinities to different acyl-CoA species and phospholipid classes vary amongst isoforms. Their ligands also include heavy metals. Interactors of plant ACBPs are further diversified due to the evolution of protein-protein interacting domains. This review summarizes our current understanding of plant ACBPs with a focus on their binding versatility. Their broad ligand range is of paramount significance in serving a multitude of functions during development and stress responses as discussed herein. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Shiu-Cheung Lung
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
| | - Mee-Len Chye
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China.
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19
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Jessen D, Roth C, Wiermer M, Fulda M. Two activities of long-chain acyl-coenzyme A synthetase are involved in lipid trafficking between the endoplasmic reticulum and the plastid in Arabidopsis. PLANT PHYSIOLOGY 2015; 167:351-66. [PMID: 25540329 PMCID: PMC4326746 DOI: 10.1104/pp.114.250365] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 12/19/2014] [Indexed: 05/18/2023]
Abstract
In plants, fatty acids are synthesized within the plastid and need to be distributed to the different sites of lipid biosynthesis within the cell. Free fatty acids released from the plastid need to be converted to their corresponding coenzyme A thioesters to become metabolically available. This activation is mediated by long-chain acyl-coenzyme A synthetases (LACSs), which are encoded by a family of nine genes in Arabidopsis (Arabidopsis thaliana). So far, it has remained unclear which of the individual LACS activities are involved in making plastid-derived fatty acids available to cytoplasmic glycerolipid biosynthesis. Because of its unique localization at the outer envelope of plastids, LACS9 was regarded as a candidate for linking plastidial fatty export and cytoplasmic use. However, data presented in this study show that LACS9 is involved in fatty acid import into the plastid. The analyses of mutant lines revealed strongly overlapping functions of LACS4 and LACS9 in lipid trafficking from the endoplasmic reticulum to the plastid. In vivo labeling experiments with lacs4 lacs9 double mutants suggest strongly reduced synthesis of endoplasmic reticulum-derived lipid precursors, which are required for the biosynthesis of glycolipids in the plastids. In conjunction with this defect, double-mutant plants accumulate significant amounts of linoleic acid in leaf tissue.
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Affiliation(s)
- Dirk Jessen
- Departments of Plant Biochemistry (D.J., M.F.) and Plant Cell Biology (C.R., M.W.), Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37077 Goettingen, Germany
| | - Charlotte Roth
- Departments of Plant Biochemistry (D.J., M.F.) and Plant Cell Biology (C.R., M.W.), Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37077 Goettingen, Germany
| | - Marcel Wiermer
- Departments of Plant Biochemistry (D.J., M.F.) and Plant Cell Biology (C.R., M.W.), Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37077 Goettingen, Germany
| | - Martin Fulda
- Departments of Plant Biochemistry (D.J., M.F.) and Plant Cell Biology (C.R., M.W.), Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37077 Goettingen, Germany
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20
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de Luna-Valdez L, Martínez-Batallar A, Hernández-Ortiz M, Encarnación-Guevara S, Ramos-Vega M, López-Bucio J, León P, Guevara-García A. Proteomic analysis of chloroplast biogenesis (clb) mutants uncovers novel proteins potentially involved in the development of Arabidopsis thaliana chloroplasts. J Proteomics 2014; 111:148-64. [DOI: 10.1016/j.jprot.2014.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 06/25/2014] [Accepted: 07/03/2014] [Indexed: 02/04/2023]
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21
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Evaluation of fatty acid composition among selected amaranth grains grown in two consecutive years. Biologia (Bratisl) 2013. [DOI: 10.2478/s11756-013-0190-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Xue JA, Mao X, Yang ZR, Wu YM, Jia XY, Zhang L, Yue AQ, Wang JP, Li RZ. Expression of yeast acyl-CoA-∆9 desaturase leads to accumulation of unusual monounsaturated fatty acids in soybean seeds. Biotechnol Lett 2013; 35:951-9. [PMID: 23397267 DOI: 10.1007/s10529-013-1149-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 01/18/2013] [Indexed: 10/27/2022]
Abstract
An acyl-CoA-Δ9 desaturase from Saccharomyces cerevisiae was expressed by subcellular-targeting in soybean (Glycine max) seeds with the goal of increasing palmitoleic acid (16:1Δ9), a high-valued fatty acid (FA), and simultaneously decreasing saturated FA in oil. The expression resulted in the conversion of palmitic acid (16:0) to 16:1Δ9 in soybean seeds. 16:1Δ9 and its elongation product cis-vaccenic acid (18:1Δ11) were increased to 17 % of the total fatty acids by plastid-targeted expression of the enzyme. Other lipid changes include the decrease of polyunsaturated FA and saturated FA, suggesting that a mechanism exists downstream in oil biosynthesis to compensate the FA alternation. This is the first time a cytosolic acyl-CoA-∆9 desaturase is functionally expressed in plastid and stronger activity was achieved than its cytosolic expression. The present study provides a new strategy for converting 16:0 to 16:1Δ9 by engineering acyl-CoA-Δ9 desaturase in commercialized oilseeds.
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Affiliation(s)
- Jin-Ai Xue
- Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu, 030801, China
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Djafi N, Humbert L, Rainteau D, Cantrel C, Zachowski A, Ruelland E. Multiple reaction monitoring mass spectrometry is a powerful tool to study glycerolipid composition in plants with different level of desaturase activity. PLANT SIGNALING & BEHAVIOR 2013; 8:e24118. [PMID: 23470727 PMCID: PMC3907394 DOI: 10.4161/psb.24118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In plants, two lipid desaturation pathways exist. A so-called prokaryotic pathway is active in plastids and responsible for unsaturation of 16 carbon fatty acids. An eukaryotic one, in the endoplasmic reticulum, acts on 18 carbon fatty acids. Desaturase activities are affected in stressed plants, and conversely, they have an impact on the capability of plants to adapt to stress. So knowing lipid unsaturation is important for physiological studies. Analysis of lipids by mass spectrometry, in the multiple reaction mode, gives access to the molecular species present in each membrane lipid class. We illustrate the powerfulness of this technique by applying it to phospholipids and galactolipids extracted from plants where the desaturation pathways are present at variable level.
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Affiliation(s)
- Nabila Djafi
- UPMC Univ Paris 06; UR 5; Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
- CNRS; EAC7180; Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
| | - Lydie Humbert
- ERL INSERM U 1057, Université Pierre et Marie Curie-Paris; Paris, France
- UMR 7203; ENS; CNRS; UPMC; Paris, France
| | - Dominique Rainteau
- ERL INSERM U 1057, Université Pierre et Marie Curie-Paris; Paris, France
- UMR 7203; ENS; CNRS; UPMC; Paris, France
| | - Catherine Cantrel
- UPMC Univ Paris 06; UR 5; Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
- CNRS; EAC7180; Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
| | - Alain Zachowski
- UPMC Univ Paris 06; UR 5; Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
- CNRS; EAC7180; Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
| | - Eric Ruelland
- UPMC Univ Paris 06; UR 5; Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
- CNRS; EAC7180; Physiologie Cellulaire et Moléculaire des Plantes; Paris, France
- Correspondence to: Eric Ruelland,
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Roston RL, Gao J, Murcha MW, Whelan J, Benning C. TGD1, -2, and -3 proteins involved in lipid trafficking form ATP-binding cassette (ABC) transporter with multiple substrate-binding proteins. J Biol Chem 2012; 287:21406-15. [PMID: 22544736 PMCID: PMC3375562 DOI: 10.1074/jbc.m112.370213] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 04/27/2012] [Indexed: 11/06/2022] Open
Abstract
Members of the ATP-binding cassette (ABC) transporter family are essential proteins in species as diverse as archaea and humans. Their domain architecture has remained relatively fixed across these species, with rare exceptions. Here, we show one exception to be the trigalactosyldiacylglycerol 1, 2, and 3 (TGD1, -2, and -3) putative lipid transporter located at the chloroplast inner envelope membrane. TGD2 was previously shown to be in a complex of >500 kDa. We demonstrate that this complex also contains TGD1 and -3 and is very stable because it cannot be broken down by gentle denaturants to form a "core" complex similar in size to standard ABC transporters. The complex was purified from Pisum sativum (pea) chloroplast envelopes by native gel electrophoresis and examined by mass spectrometry. Identified proteins besides TGD1, -2, or -3 included a potassium efflux antiporter and a TIM17/22/23 family protein, but these were shown to be in separate high molecular mass complexes. Quantification of the complex components explained the size of the complex because 8-12 copies of the substrate-binding protein (TGD2) were found per functional transporter.
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Affiliation(s)
- Rebecca L. Roston
- From the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 and
| | - Jinpeng Gao
- From the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 and
| | - Monika W. Murcha
- the Australian Research Council Centre of Excellence Plant Energy Biology, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - James Whelan
- the Australian Research Council Centre of Excellence Plant Energy Biology, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Christoph Benning
- From the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 and
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25
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Chloroplast lipid synthesis and lipid trafficking through ER–plastid membrane contact sites. Biochem Soc Trans 2012; 40:457-63. [DOI: 10.1042/bst20110752] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Plant chloroplasts contain an intricate photosynthetic membrane system, the thylakoids, and are surrounded by two envelope membranes at which thylakoid lipids are assembled. The glycoglycerolipids mono- and digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol as well as phosphatidylglycerol, are present in thylakoid membranes, giving them a unique composition. Fatty acids are synthesized in the chloroplast and are either directly assembled into thylakoid lipids at the envelope membranes or exported to the ER (endoplasmic reticulum) for extraplastidic lipid assembly. A fraction of lipid precursors is reimported into the chloroplast for the synthesis of thylakoid lipids. Thus polar lipid assembly in plants requires tight co-ordination between the chloroplast and the ER and necessitates inter-organelle lipid trafficking. In the present paper, we discuss the current knowledge of the export of fatty acids from the chloroplast and the import of chloroplast lipid precursors assembled at the ER. Direct membrane contact sites between the ER and the chloroplast outer envelopes are discussed as possible conduits for lipid transfer.
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Tjellström H, Yang Z, Allen DK, Ohlrogge JB. Rapid kinetic labeling of Arabidopsis cell suspension cultures: implications for models of lipid export from plastids. PLANT PHYSIOLOGY 2012; 158:601-11. [PMID: 22128138 PMCID: PMC3271753 DOI: 10.1104/pp.111.186122] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 11/22/2011] [Indexed: 05/18/2023]
Abstract
Cell cultures allow rapid kinetic labeling experiments that can provide information on precursor-product relationships and intermediate pools. T-87 suspension cells are increasingly used in Arabidopsis (Arabidopsis thaliana) research, but there are no reports describing their lipid composition or biosynthesis. To facilitate application of T-87 cells for analysis of glycerolipid metabolism, including tests of gene functions, we determined composition and accumulation of lipids of light- and dark-grown cultures. Fatty acid synthesis in T-87 cells was 7- to 8-fold higher than in leaves. Similar to other plant tissues, phosphatidylcholine (PC) and phosphatidylethanolamine were major phospholipids, but galactolipid levels were 3- to 4-fold lower than Arabidopsis leaves. Triacylglycerol represented 10% of total acyl chains, a greater percentage than in most nonseed tissues. The initial steps in T-87 cell lipid assembly were evaluated by pulse labeling cultures with [(14)C]acetate and [(14)C]glycerol. [(14)C]acetate was very rapidly incorporated into PC, preferentially at sn-2 and without an apparent precursor-product relationship to diacylglycerol (DAG). By contrast, [(14)C]glycerol most rapidly labeled DAG. These results indicate that acyl editing of PC is the major pathway for initial incorporation of fatty acids into glycerolipids of cells derived from a 16:3 plant. A very short lag time (5.4 s) for [(14)C]acetate labeling of PC implied channeled incorporation of acyl chains without mixing with the bulk acyl-CoA pool. Subcellular fractionation of pea (Pisum sativum) leaf protoplasts indicated that 30% of lysophosphatidylcholine acyltransferase activity colocalized with chloroplasts. Together, these data support a model in which PC participates in trafficking of newly synthesized acyl chains from plastids to the endoplasmic reticulum.
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27
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Roston R, Gao J, Xu C, Benning C. Arabidopsis chloroplast lipid transport protein TGD2 disrupts membranes and is part of a large complex. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 66:759-69. [PMID: 21309871 DOI: 10.1111/j.1365-313x.2011.04536.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In most plants the assembly of the photosynthetic thylakoid membrane requires lipid precursors synthesized at the endoplasmic reticulum (ER). Thus, the transport of lipids from the ER to the chloroplast is essential for biogenesis of the thylakoids. TGD2 is one of four proteins in Arabidopsis required for lipid import into the chloroplast, and was found to bind phosphatidic acid in vitro. However, the significance of phosphatidic acid binding for the function of TGD2 in vivo and TGD2 interaction with membranes remained unclear. Developing three functional assays probing how TGD2 affects lipid bilayers in vitro, we show that it perturbs membranes to the point of fusion, causes liposome leakage and redistributes lipids in the bilayer. By identifying and characterizing five new mutant alleles, we demonstrate that these functions are impaired in specific mutants with lipid phenotypes in vivo. At the structural level, we show that TGD2 is part of a protein complex larger than 500 kDa, the formation of which is disrupted in two mutant alleles, indicative of the biological relevance of this TGD2-containing complex. Based on the data presented, we propose that TGD2, as part of a larger complex, forms a lipid transport conduit between the inner and outer chloroplast envelope membranes, with its N terminus anchored in the inner membrane and its C terminus binding phosphatidic acid in the outer membrane.
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Affiliation(s)
- Rebecca Roston
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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28
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Shen W, Li JQ, Dauk M, Huang Y, Periappuram C, Wei Y, Zou J. Metabolic and transcriptional responses of glycerolipid pathways to a perturbation of glycerol 3-phosphate metabolism in Arabidopsis. J Biol Chem 2010; 285:22957-65. [PMID: 20304913 PMCID: PMC2906289 DOI: 10.1074/jbc.m109.097758] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 03/11/2010] [Indexed: 11/06/2022] Open
Abstract
Glycerolipid synthesis in plants involves two major metabolic pathways compartmentalized in the chloroplasts and cytosol, respectively. Although these two parallel pathways are regulated with considerable flexibility, the factors mediating this process remain unclear. To investigate the influence of glycerol 3-phosphate (Gly-3-P) on the interactions of the glycerolipid pathways, we generated transgenic Arabidopsis lines with a feedback-resistant Gly-3-P dehydrogenase gene (gpsA(FR)) from Escherichia coli. gpsA(FR) was detected in the cytosol, but augmented Gly-3-P levels were observed in the cytosol as well as in chloroplasts. Glycerolipid composition and fatty acid positional distribution analyses revealed an altered fatty acid flux that affected not only the molar ratios of glycerolipid species but also their fatty acid composition. To decipher this complex pathway, a transgenic line was subjected to lipidomic analysis and a global gene-expression survey. The results revealed that changes in Gly-3-P metabolism caused altered expression of a broad array of genes. When viewed from the perspective of glycerolipid metabolism, coherent networks emerged, revealing that many enzymatic components of the glycerolipid pathways operate in a modular manner under the influence of Gly-3-P. Transcript levels of the enzymes involved in the prokaryotic pathway were mostly induced, whereas genes of the eukaryotic pathway enzymes were largely suppressed. Hence, the gene-expression changes were consistent with the detected biochemical phenotype. Our results suggest that Gly-3-P modulates the balance of the two glycerolipid pathways in Arabidopsis by influencing both metabolic flux and gene transcription.
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Affiliation(s)
- Wenyun Shen
- From the
Plant Biotechnology Institute, National Research Council Canada, Saskatoon, Saskatchewan S7N OW9 and
| | - John Qiang Li
- From the
Plant Biotechnology Institute, National Research Council Canada, Saskatoon, Saskatchewan S7N OW9 and
- the
Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Melanie Dauk
- From the
Plant Biotechnology Institute, National Research Council Canada, Saskatoon, Saskatchewan S7N OW9 and
| | - Yi Huang
- From the
Plant Biotechnology Institute, National Research Council Canada, Saskatoon, Saskatchewan S7N OW9 and
| | - Cyril Periappuram
- From the
Plant Biotechnology Institute, National Research Council Canada, Saskatoon, Saskatchewan S7N OW9 and
| | - Yangdou Wei
- the
Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Jitao Zou
- From the
Plant Biotechnology Institute, National Research Council Canada, Saskatoon, Saskatchewan S7N OW9 and
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29
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Kunst L, Browse J, Somerville C. Altered regulation of lipid biosynthesis in a mutant of Arabidopsis deficient in chloroplast glycerol-3-phosphate acyltransferase activity. Proc Natl Acad Sci U S A 2010; 85:4143-7. [PMID: 16593939 PMCID: PMC280382 DOI: 10.1073/pnas.85.12.4143] [Citation(s) in RCA: 188] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The leaf membrane lipids of many plant species, including Arabidopsis thaliana (L.) Heynh., are synthesized by two complementary pathways that are associated with the chloroplast and the endoplasmic reticulum. By screening directly for alterations in lipid acyl-group composition, we have identified several mutants of Arabidopsis that lack the plastid pathway because of a deficiency in activity of the first enzyme in the plastid pathway of glycerolipid synthesis, acyl-ACP:sn-glycerol-3-phosphate acyltransferase (EC 2.3.1.15) (where ACP is acyl carrier protein). The lesion results in an increased synthesis of lipids by the cytoplasmic pathway that largely compensates for the loss of the plastid pathway and provides nearly normal amounts of all the lipids required for chloroplast biogenesis. However, the fatty acid composition of the leaf membrane lipids of the mutants is altered because the acyltransferases associated with the two pathways normally exhibit different substrate specificities. The remarkable flexibility of the system provides an insight into the nature of the regulatory mechanisms that allocate lipids for membrane biogenesis.
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Affiliation(s)
- L Kunst
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824
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30
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Lipolysis of natural long chain and synthetic medium chain galactolipids by pancreatic lipase-related protein 2. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:508-16. [DOI: 10.1016/j.bbalip.2010.01.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 12/17/2009] [Accepted: 01/03/2010] [Indexed: 11/24/2022]
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31
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Kaczmarzyk D, Fulda M. Fatty acid activation in cyanobacteria mediated by acyl-acyl carrier protein synthetase enables fatty acid recycling. PLANT PHYSIOLOGY 2010; 152:1598-610. [PMID: 20061450 PMCID: PMC2832271 DOI: 10.1104/pp.109.148007] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 12/30/2009] [Indexed: 05/21/2023]
Abstract
In cyanobacteria fatty acids destined for lipid synthesis can be synthesized de novo, but also exogenous free fatty acids from the culture medium can be directly incorporated into lipids. Activation of exogenous fatty acids is likely required prior to their utilization. To identify the enzymatic activity responsible for activation we cloned candidate genes from Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942 and identified the encoded proteins as acyl-acyl carrier protein synthetases (Aas). The enzymes catalyze the ATP-dependent esterification of fatty acids to the thiol of acyl carrier protein. The two protein sequences are only distantly related to known prokaryotic Aas proteins but they display strong similarity to sequences that can be found in almost all organisms that perform oxygenic photosynthesis. To investigate the biological role of Aas activity in cyanobacteria, aas knockout mutants were generated in the background of Synechocystis sp. PCC 6803 and S. elongatus PCC 7942. The mutant strains showed two phenotypes characterized by the inability to utilize exogenous fatty acids and by the secretion of endogenous fatty acids into the culture medium. The analyses of extracellular and intracellular fatty acid profiles of aas mutant strains as well as labeling experiments indicated that the detected free fatty acids are released from membrane lipids. The data suggest a considerable turnover of lipid molecules and a role for Aas activity in recycling the released fatty acids. In this model, lipid degradation represents a third supply of fatty acids for lipid synthesis in cyanobacteria.
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Abstract
Chloroplasts are the defining organelle of photoautotrophic plant cells. Photosynthetic light reactions and electron transport are the functions of an elaborate thylakoid membrane system inside chloroplasts. The lipid composition of photosynthetic membranes is characterized by a substantial fraction of nonphosphorous galactoglycerolipids reflecting the need of sessile plants to conserve phosphorus. Lipid transport and assembly of glycerolipids play an essential role in the biogenesis of the photosynthetic apparatus in developing chloroplasts. During chloroplast biogenesis, fatty acids are synthesized in the plastid and are exported to the endoplasmic reticulum, where they are incorporated into membrane lipids. Alternatively, lipids can also be assembled de novo at the inner envelope membrane of plastids in many plants. A rich repertoire of lipid exchange mechanisms involving the thylakoid membranes, the chloroplast inner and outer envelope membranes, and the endoplasmic reticulum is emerging. Studies of thylakoid biogenesis provide new insights into the general mechanisms of intermembrane lipid transfer.
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Affiliation(s)
- Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA.
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33
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Chapter 12 The Anionic Chloroplast Membrane Lipids: Phosphatidylglycerol and Sulfoquinovosyldiacylglycerol. THE CHLOROPLAST 2010. [DOI: 10.1007/978-90-481-8531-3_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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34
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Lu B, Benning C. A 25-amino acid sequence of the Arabidopsis TGD2 protein is sufficient for specific binding of phosphatidic acid. J Biol Chem 2009; 284:17420-7. [PMID: 19416982 PMCID: PMC2719382 DOI: 10.1074/jbc.m109.016014] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 05/01/2009] [Indexed: 11/06/2022] Open
Abstract
Genetic analysis suggests that the TGD2 protein of Arabidopsis is required for the biosynthesis of endoplasmic reticulum derived thylakoid lipids. TGD2 is proposed to be the substrate-binding protein of a presumed lipid transporter consisting of the TGD1 (permease) and TGD3 (ATPase) proteins. The TGD1, -2, and -3 proteins are localized in the inner chloroplast envelope membrane. TGD2 appears to be anchored with an N-terminal membrane-spanning domain into the inner envelope membrane, whereas the C-terminal domain faces the intermembrane space. It was previously shown that the C-terminal domain of TGD2 binds phosphatidic acid (PtdOH). To investigate the PtdOH binding site of TGD2 in detail, the C-terminal domain of the TGD2 sequence lacking the transit peptide and transmembrane sequences was fused to the C terminus of the Discosoma sp. red fluorescent protein (DR). This greatly improved the solubility of the resulting DR-TGD2C fusion protein following production in Escherichia coli. The DR-TGD2C protein bound PtdOH with high specificity, as demonstrated by membrane lipid-protein overlay and liposome association assays. Internal deletion and truncation mutagenesis identified a previously undescribed minimal 25-amino acid fragment in the C-terminal domain of TGD2 that is sufficient for PtdOH binding. Binding characteristics of this 25-mer were distinctly different from those of TGD2C, suggesting that additional sequences of TGD2 providing the proper context for this 25-mer are needed for wild type-like PtdOH binding.
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Affiliation(s)
- Binbin Lu
- From the Department of Biochemistry and Molecular Biology and
- the Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
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35
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Moellering ER, Miller R, Benning C. Molecular Genetics of Lipid Metabolism in the Model Green Alga Chlamydomonas reinhardtii. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/978-90-481-2863-1_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
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36
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37
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Xu C, Fan J, Cornish AJ, Benning C. Lipid trafficking between the endoplasmic reticulum and the plastid in Arabidopsis requires the extraplastidic TGD4 protein. THE PLANT CELL 2008; 20:2190-204. [PMID: 18689504 PMCID: PMC2553622 DOI: 10.1105/tpc.108.061176] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 07/19/2008] [Accepted: 07/27/2008] [Indexed: 05/18/2023]
Abstract
The development of chloroplasts in Arabidopsis thaliana requires extensive lipid trafficking between the endoplasmic reticulum (ER) and the plastid. The biosynthetic enzymes for the final steps of chloroplast lipid assembly are associated with the plastid envelope membranes. For example, during biosynthesis of the galactoglycerolipids predominant in photosynthetic membranes, galactosyltransferases associated with these membranes transfer galactosyl residues from UDP-Gal to diacylglycerol. In Arabidopsis, diacylglycerol can be derived from the ER or the plastid. Here, we describe a mutant of Arabidopsis, trigalactosyldiacylglycerol4 (tgd4), in which ER-derived diacylglycerol is not available for galactoglycerolipid biosynthesis. This mutant accumulates diagnostic oligogalactoglycerolipids, hence its name, and triacylglycerol in its tissues. The TGD4 gene encodes a protein that appears to be associated with the ER membranes. Mutant ER microsomes show a decreased transfer of lipids to isolated plastids consistent with in vivo labeling data, indicating a disruption of ER-to-plastid lipid transfer. The complex lipid phenotype of the mutant is similar to that of the tgd1,2,3 mutants disrupted in components of a lipid transporter of the inner plastid envelope membrane. However, unlike the TGD1,2,3 complex, which is proposed to transfer phosphatidic acid through the inner envelope membrane, TGD4 appears to be part of the machinery mediating lipid transfer between the ER and the outer plastid envelope membrane. The extent of direct ER-to-plastid envelope contact sites is not altered in the tgd4 mutant. However, this does not preclude a possible function of TGD4 in those contact sites as a conduit for lipid transfer between the ER and the plastid.
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Affiliation(s)
- Changcheng Xu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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38
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Maeda H, Sage TL, Isaac G, Welti R, Dellapenna D. Tocopherols modulate extraplastidic polyunsaturated fatty acid metabolism in Arabidopsis at low temperature. THE PLANT CELL 2008; 20:452-70. [PMID: 18314499 PMCID: PMC2276453 DOI: 10.1105/tpc.107.054718] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 01/04/2008] [Accepted: 02/09/2008] [Indexed: 05/20/2023]
Abstract
Tocopherols (vitamin E) are synthesized in plastids and have long been assumed to have essential functions restricted to these organelles. We previously reported that the vitamin e-deficient2 (vte2) mutant of Arabidopsis thaliana is defective in transfer cell wall development and photoassimilate transport at low temperature (LT). Here, we demonstrate that LT-treated vte2 has a distinct composition of polyunsaturated fatty acids (PUFAs): lower levels of linolenic acid (18:3) and higher levels of linoleic acid (18:2) compared with the wild type. Enhanced 18:3 oxidation was not involved, as indicated by the limited differences in oxidized lipid species between LT-treated vte2 and the wild type and by a lack of impact on the LT-induced vte2 phenotype in a vte2 fad3 fad7 fad8 quadruple mutant deficient in 18:3. PUFA changes in LT-treated vte2 occur primarily in phospholipids due to reduced conversion of dienoic to trienoic fatty acids in the endoplasmic reticulum (ER) pathway. Introduction of the ER fatty acid desaturase mutation, fad2, and to a lesser extent the plastidic fad6 mutation into the vte2 background suppressed the LT-induced vte2 phenotypes, including abnormal transfer cell wall development. These results provide biochemical and genetic evidence that plastid-synthesized tocopherols modulate ER PUFA metabolism early in the LT adaptation response of Arabidopsis.
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Affiliation(s)
- Hiroshi Maeda
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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39
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Bates PD, Ohlrogge JB, Pollard M. Incorporation of newly synthesized fatty acids into cytosolic glycerolipids in pea leaves occurs via acyl editing. J Biol Chem 2007; 282:31206-16. [PMID: 17728247 DOI: 10.1074/jbc.m705447200] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In expanding pea leaves, over 95% of fatty acids (FA) synthesized in the plastid are exported for assembly of eukaryotic glycerolipids. It is often assumed that the major products of plastid FA synthesis (18:1 and 16:0) are first incorporated into 16:0/18:1 and 18:1/18:1 molecular species of phosphatidic acid (PA), which are then converted to phosphatidylcholine (PC), the major eukaryotic phospholipid and site of acyl desaturation. However, by labeling lipids of pea leaves with [(14)C]acetate, [(14)C]glycerol, and [(14)C]carbon dioxide, we demonstrate that acyl editing is an integral component of eukaryotic glycerolipid synthesis. First, no precursor-product relationship between PA and PC [(14)C]acyl chains was observed at very early time points. Second, analysis of PC molecular species at these early time points showed that >90% of newly synthesized [(14)C]18:1 and [(14)C]16:0 acyl groups were incorporated into PC alongside a previously synthesized unlabeled acyl group (18:2, 18:3, or 16:0). And third, [(14)C]glycerol labeling produced PC molecular species highly enriched with 18:2, 18:3, and 16:0 FA, and not 18:1, the major product of plastid fatty acid synthesis. In conclusion, we propose that most newly synthesized acyl groups are not immediately utilized for PA synthesis, but instead are incorporated directly into PC through an acyl editing mechanism that operates at both sn-1 and sn-2 positions. Additionally, the acyl groups removed by acyl editing are largely used for the net synthesis of PC through glycerol 3-phosphate acylation.
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Affiliation(s)
- Philip D Bates
- Department of Biochemistry, Michigan State University, East Lansing, Michigan 48824, USA
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Awai K, Xu C, Lu B, Benning C. Lipid trafficking between the endoplasmic reticulum and the chloroplast. Biochem Soc Trans 2006; 34:395-8. [PMID: 16709171 DOI: 10.1042/bst0340395] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The photosynthetic (thylakoid) membrane of plants is one of the most extensive biological cell membrane systems found in Nature. It harbours the photosynthetic apparatus, which is essential to life on Earth as carbon dioxide is fixed and atmospheric oxygen released by photosynthesis. Lipid biosynthetic enzymes of different subcellular compartments participate in the biogenesis of the thylakoid membrane system. This process requires the extensive exchange of lipid precursors between the chloroplast and the ER (endoplasmic reticulum). The underlying lipid trafficking phenomena are not yet understood at the mechanistic level, but genetic mutants of the model plant Arabidopsis thaliana with disruptions in lipid trafficking between the ER and the chloroplast have recently become available. Their study has led to the identification of components of the lipid transfer machinery at the inner chloroplast envelope.
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Affiliation(s)
- K Awai
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, 48824, USA
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41
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Xu C, Yu B, Cornish AJ, Froehlich JE, Benning C. Phosphatidylglycerol biosynthesis in chloroplasts of Arabidopsis mutants deficient in acyl-ACP glycerol-3- phosphate acyltransferase. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 47:296-309. [PMID: 16774646 DOI: 10.1111/j.1365-313x.2006.02790.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The biosynthesis of phosphatidylglycerol represents a central pathway in lipid metabolism in all organisms. The enzyme catalyzing the first reaction of the pathway in the plastid, glycerol-3-phosphate acyl-acyl carrier protein acyltransferase, is thought to be encoded in Arabidopsis by the ATS1 locus. A number of genetic mutants deficient in this activity have been described. However, the corresponding mutant alleles have not yet been analyzed at the molecular level and a causal relationship between the mutant phenotypes and a deficiency at the ATS1 locus has not been established. The presence in all known ats1 mutants of near wild-type amounts of phosphatidylglycerol raised the question of whether an alternative pathway of phosphatidylglycerol assembly in the plastid exists. However, detailed analysis of several independent ats1 mutant alleles revealed that all are leaky. Reduction by RNAi of ats1-1 RNA levels in the ats1-1 mutant background led to a more severe growth phenotype (small green plants and reduced seed set), but did not decrease the relative amount of phosphatidylglycerol. In contrast, when the amount of ATS2 mRNA encoding the plastidic lysophosphatidic acid acyltransferase catalyzing the second reaction of the pathway was reduced by RNAi in the ats1-1 mutant background, phosphatidylglycerol amounts decreased, leading to a growth phenotype (small pale-yellow plants) that is reminiscent of the pgp1-1 mutant deficient in a late step of plastidic phosphatidylglycerol biosynthesis. These observations indicate coordinated regulation of plastid lipid metabolism and plant development.
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Affiliation(s)
- Changcheng Xu
- Department of Biochemistry, Michigan State University, East Lansing, MI 48824, USA
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Benning C, Xu C, Awai K. Non-vesicular and vesicular lipid trafficking involving plastids. CURRENT OPINION IN PLANT BIOLOGY 2006; 9:241-7. [PMID: 16603410 DOI: 10.1016/j.pbi.2006.03.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Accepted: 03/22/2006] [Indexed: 05/08/2023]
Abstract
In plants, newly synthesized fatty acids are either directly incorporated into glycerolipids in the plastid or exported and assembled into lipids at the endoplasmic reticulum (ER). ER-derived glycerolipids serve as building blocks for extraplastidic membranes. Alternatively, they can return to the plastid where their diacylglycerol backbone is incorporated into the glycerolipids of the photosynthetic membranes, the thylakoids. Thylakoid lipids are assembled at the plastid envelope membranes and are transferred to the thylakoids. Under phosphate-limited growth conditions, galactolipids are exported from the outer plastid envelope membranes to extraplastidic membranes. Proteins, such as TRIGALACTOSYLDIACYLGLYCEROL1 (TGD1) or VESICLE-INDUCING PROTEIN IN PLASTIDS1 (VIPP1), which are involved in different aspects of plastid lipid trafficking phenomena have recently been identified and mechanistic models that are based on the analysis of these components have begun to emerge.
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Affiliation(s)
- Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48823, USA.
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43
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Xu C, Fan J, Froehlich JE, Awai K, Benning C. Mutation of the TGD1 chloroplast envelope protein affects phosphatidate metabolism in Arabidopsis. THE PLANT CELL 2005; 17:3094-110. [PMID: 16199613 PMCID: PMC1276032 DOI: 10.1105/tpc.105.035592] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Phosphatidate (PA) is a central metabolite of lipid metabolism and a signaling molecule in many eukaryotes, including plants. Mutations in a permease-like protein, TRIGALACTOSYLDIACYLGLYCEROL1 (TGD1), in Arabidopsis thaliana caused the accumulation of triacylglycerols, oligogalactolipids, and PA. Chloroplast lipids were altered in their fatty acid composition consistent with an impairment of lipid trafficking from the endoplasmic reticulum (ER) to the chloroplast and a disruption of thylakoid lipid biosynthesis from ER-derived precursors. The process mediated by TGD1 appears to be essential as mutation of the protein caused a high incidence of embryo abortion. Isolated tgd1 mutant chloroplasts showed a decreased ability to incorporate PA into galactolipids. The TGD1 protein was localized to the inner chloroplast envelope and appears to be a component of a lipid transporter. As even partial disruption of TGD1 function has drastic consequences on central lipid metabolism, the tgd1 mutant provides a tool to explore regulatory mechanisms governing lipid homeostasis and lipid trafficking in plants.
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Affiliation(s)
- Changcheng Xu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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44
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Benning C, Ohta H. Three Enzyme Systems for Galactoglycerolipid Biosynthesis Are Coordinately Regulated in Plants. J Biol Chem 2005; 280:2397-400. [PMID: 15590685 DOI: 10.1074/jbc.r400032200] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Galactoglycerolipids, in which galactose is bound at the glycerol sn-3 position in O-glycosidic linkage to diacylglycerol, are abundant in plants and photosynthetic bacteria, where they constitute the bulk of the polar lipids of the photosynthetic membranes. Galactoglycerolipid biosynthesis in plants is highly compartmentalized involving enzymes at the endoplasmic reticulum and the two chloroplast envelopes. This peculiar organization requires extensive trafficking of lipid precursors. It is now increasingly apparent that there are three different sets of lipid galactosyltransferases capable of galactoglycerolipid biosynthesis in the model plant Arabidopsis. Two enzymes, MGD1 and DGD1, provide the bulk of galactoglycerolipids in the chloroplast and in photosynthetic tissues in general. Under phosphate-limited growth conditions and in non-photosynthetic tissues MGD2/3 and DGD2 are highly active. Moreover, galactoglycerolipids produced by this second pathway are often found in extraplastidic membranes. Although these galactosyltransferases use UDP-Gal as the galactose donor, a third pathway involves a processive enzyme, which transfers galactose from one galactolipid to another.
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Affiliation(s)
- Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, USA.
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45
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Benning C, Xu C, Awai K. Arabidopsis as a genetic model for interorganelle lipid trafficking. GENETIC ENGINEERING 2004; 26:1-11. [PMID: 15387289 DOI: 10.1007/978-0-306-48573-2_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Affiliation(s)
- Christoph Benning
- Department of Biochemistry and Molecular Biology Michigan State University East Lansing, MI 48824-1319, USA
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46
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Bonaventure G, Bao X, Ohlrogge J, Pollard M. Metabolic responses to the reduction in palmitate caused by disruption of the FATB gene in Arabidopsis. PLANT PHYSIOLOGY 2004; 135:1269-79. [PMID: 15266055 PMCID: PMC519046 DOI: 10.1104/pp.104.043372] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 04/13/2004] [Accepted: 04/13/2004] [Indexed: 05/18/2023]
Abstract
Disruption of the FATB gene in Arabidopsis results in a two-thirds reduction in saturated fatty acids, largely palmitate, in the leaf extra-plastidic phospholipids and a reduction in the growth rate of the mutant compared to wild type (Bonaventure G, Salas JJ, Pollard MR, Ohlrogge JB [2003] Plant Cell 15: 1020-1033). In this study, we report that although fatb-ko seedlings grow more slowly than wild type, the rate of fatty acid synthesis in leaves of the mutant increases by 40%. This results in approximately the same amount of palmitate exported from the plastid as in wild type but an increase in oleate export of about 55%. To maintain constant amounts of fatty acids in leaves, thereby counterbalancing their higher rate of production, the mutant also increases its rate of fatty acid degradation. Although fatb-ko leaves have higher rates of fatty acid synthesis and turnover, the relative proportions of membrane lipids are similar to wild type. Thus, homeostatic mechanisms to preserve membrane compositions compensate for substantial changes in rates of fatty acid and glycerolipid metabolism in the mutant. Pulse-chase labeling studies show that in fatb-ko leaves there is a net increase in the synthesis of both prokaryotic and eukaryotic lipids and consequently of their turnover. The net loss of palmitate from phosphatidylcholine plus phosphatidylethanolamine is similar for wild type and mutant, suggesting that mechanisms are not present that can preferentially preserve the saturated fatty acids. In summary, the leaf cell responds to the loss of saturated fatty acid production in the fatb-ko mutant by increasing both fatty acid synthesis and degradation, but in doing so the mechanisms for increased fatty acid turnover contribute to the lowering of the percentage of saturated fatty acids found in eukaryotic lipids.
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Affiliation(s)
- Gustavo Bonaventure
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824, USA
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47
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Abstract
The model for export of fatty acids from plastids proposes that the acyl-ACP (acyl carrier protein) product of de novo fatty acid synthesis is hydrolyzed in the stroma by acyl-ACP thioesterases and the free fatty acid (FFA) released is then transferred to the outer envelope of the plastid where it is reactivated to acyl-CoA for utilization in cytosolic glycerolipid synthesis. Experiments were performed to assess whether the delivery of nascent FFA from the stroma for long chain acyl-CoA synthesis (LACS) occurs via simple diffusion or a more complex mechanism. The flux through the in vivo FFA pool was estimated using kinetic labeling experiments with spinach and pea leaves. The maximum half-life for FFA in the export pool was < or =1 s. Isolated pea chloroplasts incubated in the light with [14C]acetate gave a linear accumulation of FFA. When CoASH and ATP were present there was also a linear accumulation of acyl-CoA thioesters (plus derived polar lipids), with no measurable lag phase (<30 s), indicating that the FFA pool supplying LACS rapidly reached steady state. The LACS reaction was also measured independently in the dark after in situ generated FFA had accumulated yielding estimates of LACS substrate-velocity relationships. Based on these experiments the LACS reaction with in situ generated FFA as substrate is only about 3% of the LACS activity required in vivo at the very low concentrations of the FFA export pool calculated from the in vivo experiment. Furthermore, bovine serum albumin rapidly removed in situ generated FFA from chloroplasts, but could not compete effectively for "nascent" FFA substrates of LACS. Together the data suggest a locally channeled pool of exported FFA that is closely linked to LACS.
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Affiliation(s)
- Abraham J K Koo
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824-1312, USA
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Li C, Liu G, Xu C, Lee GI, Bauer P, Ling HQ, Ganal MW, Howe GA. The tomato suppressor of prosystemin-mediated responses2 gene encodes a fatty acid desaturase required for the biosynthesis of jasmonic acid and the production of a systemic wound signal for defense gene expression. THE PLANT CELL 2003; 15:1646-61. [PMID: 12837953 PMCID: PMC165407 DOI: 10.1105/tpc.012237] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2003] [Accepted: 04/17/2003] [Indexed: 05/18/2023]
Abstract
Genetic analysis of the wound response pathway in tomato indicates that systemin and its precursor protein, prosystemin, are upstream components of a defensive signaling cascade that involves the synthesis and subsequent action of the octadecatrienoic acid (18:3)-derived plant hormone jasmonic acid (JA). The suppressor of prosystemin-mediated responses2 (spr2) mutation, which was isolated previously as a suppressor of (pro)systemin-mediated signaling, impairs wound-induced JA biosynthesis and the production of a long-distance signal for the expression of defensive Proteinase inhibitor genes. Using a map-based cloning approach, we demonstrate here that Spr2 encodes a chloroplast fatty acid desaturase involved in JA biosynthesis. Loss of Spr2 function reduced the 18:3 content of leaves to <10% of wild-type levels, abolished the accumulation of hexadecatrienoic acid, and caused a corresponding increase in the level of dienoic fatty acids. The effect of spr2 on the fatty acyl content of various classes of glycerolipids indicated that the Spr2 gene product catalyzes most, if not all, omega3 fatty acid desaturation within the "prokaryotic pathway" for lipid synthesis in tomato leaves. Despite the reduced levels of trienoic fatty acids, spr2 plants exhibited normal growth, development, and reproduction. However, the mutant was compromised in defense against attack by tobacco hornworm larvae. These results indicate that jasmonate synthesis from chloroplast pools of 18:3 is required for wound- and systemin-induced defense responses and support a role for systemin in the production of a transmissible signal that is derived from the octadecanoid pathway.
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Affiliation(s)
- Chuanyou Li
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
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49
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Block MA, Dorne AJ, Joyard J, Douce R. The acyl-CoA synthetase and acyl-CoA thioesterase are located on the outer and inner membrane of the chloroplast envelope, respectively. FEBS Lett 2001. [DOI: 10.1016/0014-5793(83)80647-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Moon H, Hazebroek J, Hildebrand DF. Changes in fatty acid composition in plant tissues expressing a mammalian delta9 desaturase. Lipids 2000; 35:471-9. [PMID: 10907781 DOI: 10.1007/s11745-000-546-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plant tissues expressing a mammalian stearoyl-CoA delta9 desaturase were reported to accumulate delta9 hexadecenoic acid (16:1), normally very minor in most plant tissues. The transgenic plants were thoroughly analyzed for alterations of individual lipids in different subcellular sites. Western blot analysis indicated that the animal desaturase was targeted to the microsomes. The delta9 16:1 was incorporated into both the sn-1 and sn-2 positions of all the major membrane lipids tested, indicating that the endoplasmic reticulum acyltransferases do not exclude unsaturated C16 fatty acids from the sn-2 position. In addition to increases in monounsaturated and decreases in saturated fatty acids, accumulation of 16:1 was accompanied by a reduction in 18:3 in all the lipids tested except phosphatidylglycerol, and increases in 18:2 in phospholipids. Total C16 fatty acid content in the galactolipids of the transgenics was significantly higher than that in the control, but those in the phospholipids were unchanged. In transgenics, delta11 18:1 was detected in the sn-1 position of the lipids tested except phosphatidylinositol and phosphatidylserine. Introduction of the animal desaturase, controlled by a seed-specific phaseolin promoter, into soybean somatic embryo resulted in a significant reduction in saturated fatty acids. Such effects were greater in cotyledons than hypocotyl-radicles. This study demonstrated that the animal desaturase can be used to decrease the levels of saturated fatty acids in a crop plant.
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Affiliation(s)
- H Moon
- Department of Agronomy, University of Kentucky, Lexington 40546-0091, USA
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