Taxonomic group: plant / Streptophyta
(Phylum: Streptophyta)
Organ / tissue: leaf
Publication DOI: 10.1074/jbc.M110066200Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Institutions: Max-Planck-Institute of Molecular Plant Physiology, Department of Molecular Physiology, Am Mühlenberg 1, 14476 Golm, Germany
The galactolipid digalactosyldiacylglycerol (DGDG), one of the main chloroplast lipids in higher plants, is believed to be synthesized by the galactolipid:galactolipid galactosyltransferase, which transfers a galactose moiety from one molecule of monogalactosyldiacylglycerol (MGDG) to another. Here, we report that Arabidopsis as well as other plant species contain two genes, DGD1 and DGD2, encoding enzymes with DGDG synthase activity. Using MGDG and UDP-galactose as substrates for in vitro assays with DGD2 we could for the first time measure DGDG synthase activity of a heterologously expressed plant cDNA. UDP-galactose, but not MGDG, serves as the galactose donor for DGDG synthesis catalyzed by DGD2, providing clear evidence for the existence of a UDP-galactose-dependent DGDG synthase in higher plants. In in vitro assays, DGD2 was capable of galactosylating DGDG, resulting in the synthesis of an oligogalactolipid tentatively identified as trigalactosyldiacylglycerol. DGD2 mRNA expression in leaves was very low but was strongly induced during growth under phosphate-limiting conditions. This induction correlates with the previously described increase in DGDG during phosphate deprivation. Therefore, in contrast to DGD1, which is responsible for the synthesis of the bulk of DGDG found in chloroplasts, DGD2 apparently is involved in the synthesis of DGDG under specific growth conditions.
Structure type: oligomer
Location inside paper: Figure 7
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.
NCBI Taxonomy refs (TaxIDs): 3702
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There is only one chemically distinct structure:
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