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Structure type: monomer
Trivial name: MGDG
Compound class: glycolipid, glycoside
Contained glycoepitopes: IEDB_136044,IEDB_137472,IEDB_141794,IEDB_190606,SB_165,SB_166,SB_187,SB_195,SB_7,SB_88

• Article ID: 11230
  Kobayashi K, Kondo M, Fukuda H, Nishimura M, Ohta H "Galactolipid synthesis in chloroplast inner envelope is essential for proper thylakoid biogenesis, photosynthesis, and embryogenesis" - Proceedings of the National Academy of Sciences of the USA 104 (2007) 17216-17221
  

  The biogenesis of thylakoid membranes, an indispensable event for the photoautotrophic growth of plants, requires a significant increase in the level of the unique thylakoid membrane lipid monogalactosyldiacylglycerol (MGDG), which constitutes the bulk of membrane lipids in chloroplasts. The final step in MGDG biosynthesis occurs in the plastid envelope and is catalyzed by MGDG synthase. Here we report the identification and characterization of an Arabidopsis mutant showing a complete defect in MGDG synthase 1. The mutant seeds germinated as small albinos only in the presence of sucrose. The seedlings lacked galactolipids and had disrupted photosynthetic membranes, leading to the complete impairment of photosynthetic ability and photoautotrophic growth. Moreover, invagination of the inner envelope, which is not seen in mature WT chloroplasts, was observed in the mutant, supporting an old hypothesis that envelope invagination is a major event in early chloroplast biogenesis. In addition to the defective seedling phenotype, embryo development was arrested in the mutant, although seeds with impaired embryos could germinate heterotrophically. These results demonstrate the importance of galactolipids not only in photosynthetic growth but also in embryogenesis.

  glycosyltransferase, thylakoid membrane, monogalactosyldiacylglycerol, monogalactosyldiacylglycerol synthase

  Publication DOI: 10.1073/pnas.0704680104
  Journal NLM ID: 7505876
  Publisher: National Academy of Sciences
  Institutions: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan, Center for Biological Resources and Informatics, okyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan, Research Center for the Evolving Earth and Planets, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan, Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan, Department of Molecular Biomechanics, School of Life Science, Graduate University of Advanced Studies, Okazaki 444-8585, Japan
  Methods: biological assays, fluorescence microscopy, 2D-TLC, genetic manipulations
  
   
  
  Arabidopsis thaliana
  CSDB ID 60937 (all data & tools)
• Article ID: 11231
  Fujii S, Kobayashi K, Nakamura Y, Wada H "Inducible knockdown of MONOGALACTOSYLDIACYLGLYCEROL SYNTHASE1 reveals roles of galactolipids in organelle differentiation in Arabidopsis cotyledons" - Plant Physiology 166 (2014) 1436-1449
  

  Monogalactosyldiacylglycerol (MGDG) is the major lipid constituent of thylakoid membranes and is essential for chloroplast biogenesis in plants. In Arabidopsis (Arabidopsis thaliana), MGDG is predominantly synthesized by inner envelope-localized MONOGALACTOSYLDIACYLGLYCEROL SYNTHASE1 (MGD1); its knockout causes albino seedlings. Because of the lethal phenotype of the null MGD1 mutant, functional details of MGDG synthesis at seedling development have remained elusive. In this study, we used an inducible gene-suppression system to investigate the impact of MGDG synthesis on cotyledon development. We created transgenic Arabidopsis lines that express an artificial microRNA targeting MGD1 (amiR-MGD1) under the control of a dexamethasone-inducible promoter. The induction of amiR-MGD1 resulted in up to 75% suppression of MGD1 expression, although the resulting phenotypes related to chloroplast development were diverse, even within a line. The strong MGD1 suppression by continuous dexamethasone treatment caused substantial decreases in galactolipid content in cotyledons, leading to severe defects in the formation of thylakoid membranes and impaired photosynthetic electron transport. Time-course analyses of the MGD1 suppression during seedling germination revealed that MGDG synthesis at the very early germination stage is particularly important for chloroplast biogenesis. The MGD1 suppression down-regulated genes associated with the photorespiratory pathway in peroxisomes and mitochondria as well as those responsible for photosynthesis in chloroplasts and caused high expression of genes for the glyoxylate cycle. MGD1 function may link galactolipid synthesis with the coordinated transcriptional regulation of chloroplasts and other organelles during cotyledon greening.

  Publication DOI: 10.1104/pp.114.250050
  Journal NLM ID: 0401224
  Publisher: American Society of Plant Biologists
  Correspondence: nakamura@gate.sinica.edu.tw, kkobayashi@bio.c.u-tokyo.ac.jp
  Institutions: Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan, PRESTO, JST, Kawaguchi, Saitama 332-0012, Japan, CREST, JST, Kawaguchi, Saitama 332-0012, Japan, Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Tapei 11529, Taiwan
  Methods: GC, biological assays, microscopy, genetic manipulations, lipid extraction
  
   
  
  Arabidopsis thaliana
  CSDB ID 60939 (all data & tools)
• Article ID: 11244
  Kelly AA, Froehlich JE, Dormann P "Disruption of the two digalactosyldiacylglycerol synthase genes DGD1 and DGD2 in Arabidopsis reveals the existence of an additional enzyme of galactolipid synthesis" - Plant Cell 15 (2003) 2694-2706
  

  Two genes (DGD1 and DGD2) are involved in the synthesis of the chloroplast lipid digalactosyldiacylglycerol (DGDG). The role of DGD2 for galactolipid synthesis was studied by isolating Arabidopsis T-DNA insertional mutant alleles (dgd2-1 and dgd2-2) and generating the double mutant line dgd1 dgd2. Whereas the growth and lipid composition of dgd2 were not affected, only trace amounts of DGDG were found in dgd1 dgd2. The growth and photosynthesis of dgd1 dgd2 were affected more severely compared with those of dgd1, indicating that the residual amount of DGDG in dgd1 is crucial for normal plant development. DGDG synthesis was increased after phosphate deprivation in the wild type, dgd1, and dgd2 but not in dgd1 dgd2. Therefore, DGD1 and DGD2 are involved in DGDG synthesis during phosphate deprivation. DGD2 was localized to the outer side of chloroplast envelope membranes. Like DGD2, heterologously expressed DGD1 uses UDP-galactose for galactosylation. Galactolipid synthesis activity for monogalactosyldiacylglycerol (MGDG), DGDG, and the unusual oligogalactolipids tri- and tetragalactosyldiacylglycerol was detected in isolated chloroplasts of all mutant lines, including dgd1 dgd2. Because dgd1 and dgd2 carry null mutations, an additional, processive galactolipid synthesis activity independent from DGD1 and DGD2 exists in Arabidopsis. This third activity, which is related to the Arabidopsis galactolipid:galactolipid galactosyltransferase, is localized to chloroplast envelope membranes and is capable of synthesizing DGDG from MGDG in the absence of UDP-galactose in vitro, but it does not contribute to net galactolipid synthesis in planta.

  Publication DOI: 10.1105/tpc.016675
  Journal NLM ID: 9208688
  Publisher: Rockville, MD: American Society of Plant Physiologists
  Correspondence: doermann@mpimp-golm.mpg.de
  Institutions: Department of Molecular Physiology, Max-Planck-Institute of Molecular Plant Physiology, 14476 Golm, Germany, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
  Methods: 1H NMR, TLC, biological assays, enzymatic assay, genetic manipulations
  
   
  
  Arabidopsis thaliana
  CSDB ID 61034 (all data & tools)
• Article ID: 11245
  Dormann P, Hoffmann-Benning S, Balbo I, Benning C "Isolation and characterization of an Arabidopsis mutant deficient in the thylakoid lipid digalactosyl diacylglycerol" - Plant Cell 7 (1995) 1801-1810
  

  The galactolipids monogalactosyl and digalactosyl diacylglycerol occur in all higher plants and are the predominant lipid components of chloroplast membranes. They are thought to be of major importance to chloroplast morphology and physiology, although direct experimental evidence is still lacking. The enzymes responsible for final assembly of galactolipids are associated with the envelope membranes of plastids, and their biochemical analysis has been notoriously difficult. Therefore, we have chosen a genetic approach to study the biosynthesis and function of galactolipids in higher plants. We isolated a mutant of Arabidopsis that is deficient in digalactosyl diacylglycerol by directly screening a mutagenized M2 population for individuals with altered leaf lipid composition. This mutant carries a recessive nuclear mutation at a single locus designated dgd1. Backcrossed mutants show stunted growth, pale green leaf color, reduced photosynthetic capability, and altered thylakoid membrane ultrastructure.

  Publication DOI: 10.1105/tpc.7.11.1801
  Journal NLM ID: 9208688
  Publisher: Rockville, MD: American Society of Plant Physiologists
  Institutions: Institut für Genbiologische Forschung Berlin GmbH, Germany
  Methods: TLC, GC, TEM, genetic manipulations, radioactive labeling
  
   
  
  Arabidopsis thaliana
  CSDB ID 61035 (all data & tools)
• Article ID: 11246
  Dormann P, Balbo I, Benning C "Arabidopsis galactolipid biosynthesis and lipid trafficking mediated by DGD1" - Science 284 (1999) 2181-2184
  

  The photosynthetic apparatus in plant cells is associated with membranes of the thylakoids within the chloroplast and is embedded into a highly specialized lipid matrix. Diacylglycerol galactolipids are common in thylakoid membranes but are excluded from all others. Isolation of the gene DGD1, encoding a galactosyltransferase-like protein, now provides insights into assembly of the thylakoid lipid matrix and subcellular lipid trafficking in Arabidopsis thaliana.

  Publication DOI: 10.1126/science.284.5423.2181
  Journal NLM ID: 0404511
  Publisher: Washington, DC: American Association for the Advancement of Science
  Correspondence: benning@pilot.msu.edu
  Institutions: Department of Biochemistry, Michigan State University, East Lansing, MI 48824, USA, ax-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476, Golm, Germany
  Methods: TLC, biological assays, genetic manipulations
  
   
  
  Arabidopsis thaliana
  CSDB ID 61038 (all data & tools)
• Article ID: 12446
  Maréchal E, Awai K, Block MA, Brun D, Masuda T, Shimada H, Takamiya K, Ohta H, Joyard J "The multigenic family of monogalactosyl diacylglycerol synthases" - Biochemical Society Transactions 28(6) (2000) 732-738
  

  Because the synthesis of monogalactosyldiacylglycerol (MGDG) is unique to plants, identified as an important marker of the plastid envelope, involved in a key step of plastid biogenesis and is the most abundant lipid on earth, MGDG synthase activity was extensively analysed at the biochemical and physiological levels. In the present paper, we present our current knowledge on the MGDG synthase's function, structure and topology in envelope membranes, and discuss possible roles in plant cell glycerolipid metabolism. The recent discovery of a multigenic family of MGDG synthases raised the possibility that multiple isoenzymes might carry out MGDG synthesis in various tissues and developmental stages.

  galactosyltransferase, galactolipid, monogalactosyldiacylglycerol, chloroplast envelope, MGDG, soMGD A, MGDG synthase type A

  NCBI PubMed ID: 11171188
  Publication DOI: 10.1042/0300-5127:0280732
  Journal NLM ID: 7506897
  Correspondence: emorechal@cea.fr
  Institutions: Departement de Biologie Moleculaire et Structurale, Laboratoire de Physiologie Cellulaire Végétale, UMR 5019 (Centre National de la Recherche Scientifique/Commissariat à l'Energie Atomique/Université Joseph Fourier), Commissariat à l'Energie Atomique-Grenoble, Grenoble, France, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
  
   
  
  (plant)
  CSDB ID 66724 (all data & tools)