Taxonomic group: plant / Streptophyta
(Phylum: Streptophyta)
Organ / tissue: leaf
Publication DOI: 10.1105/tpc.016675Journal NLM ID: 9208688Publisher: 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
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.
Structure type: oligomer
Location inside paper: Table 3
Trivial name: DGDG
Contained glycoepitopes: IEDB_134624,IEDB_136044,IEDB_136906,IEDB_137472,IEDB_141794,IEDB_151528,IEDB_190606,IEDB_742248,SB_163,SB_165,SB_166,SB_187,SB_195,SB_7,SB_88
Methods: 1H NMR, TLC, biological assays, enzymatic assay, genetic manipulations
Comments, role: In wild-type Arabidopsis, monogalactosyldiacylglycerol (MGDG) contains high amounts of 16:3 and 18:3 fatty acids, whereas digalactosyldiacylglycerol (DGDG) contains mostly 16:0 and 18:3 fatty acids.
Related record ID(s): 61034
NCBI Taxonomy refs (TaxIDs): 3702
Show glycosyltransferases
There is only one chemically distinct structure:
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