A Genetic Approach to Investigating Membrane Lipid Structure and Photosynthetic Function

Vijayan, Perumal; Routaboul, Jean‐Marc; Browse, John

doi:10.1007/0-306-48087-5_14

Cited by 11 publications

(14 citation statements)

References 83 publications

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“…3 Indeed, in this study a second cDNA (DGD2) was isolated from Arabidopsis encoding a functionally active DGDG synthase. The amino acid sequence of DGD2 was very similar to the C-terminal, glycosyltransferase-like part of DGD1 (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Lipid extracts from chloroplasts were used as standards for oligogalactolipids, because they were found to be enriched in TriGDG and TetraGDG. 3 DGDG Synthase Assay-DGDG synthase assays with different substrates were done with recombinant E. coli membrane proteins according to Heemskerk et al (13) with some alterations as described below. Nonradioactive MGDG (50 nmol) or radiolabeled [ 14 C]MGDG (9.7 nmol) dissolved in chloroform/methanol (2:1, v/v) was added to a glass vial, and the solvent was evaporated with nitrogen gas.…”

Section: Methodsmentioning

confidence: 99%

“…In contrast to animals, yeast, and many bacteria, plant membranes contain high amounts of the two galactolipids, monogalactosyldiacylglycerol (MGDG) 1 and digalactosyldiacylglycerol (DGDG) (1)(2)(3). These galactolipids are highly abundant in thylakoids, intricate membrane systems in chloroplasts containing the complexes of photosystem I and photosystem II.…”

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confidence: 99%

“…(ii) Chloroplasts isolated from dgd1 plants were capable of synthesizing DGDG in similar amounts as compared with wild type (14). 3 (iii) Upon phosphate deprivation, wild type and dgd1 mutant plants accumulate high amounts of DGDG (20). The additional amount of DGDG produced during phosphate deprivation was suggested to be associated with the chloroplast as well as with extraplastidic membranes, where it presumably substitutes for phospholipids.…”

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confidence: 99%

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DGD2, an Arabidopsis Gene Encoding a UDP-Galactose-dependent Digalactosyldiacylglycerol Synthase Is Expressed during Growth under Phosphate-limiting Conditions

Kelly

Dörmann

2002

Journal of Biological Chemistry

173

125

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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. In contrast to animals, yeast, and many bacteria, plant membranes contain high amounts of the two galactolipids, monogalactosyldiacylglycerol (MGDG) 1 and digalactosyldiacylglycerol (DGDG) (1-3). These galactolipids are highly abundant in thylakoids, intricate membrane systems in chloroplasts containing the complexes of photosystem I and photosystem II. For a long time the elucidation of the biosynthesis of plant galactolipids has proven extremely difficult. Biochemical labeling experiments with chloroplast membranes suggested that MGDG and DGDG are synthesized by sequential galactosylation of diacylglycerol (e.g. Refs. 4 and 5). Only in the recent past, the first genes encoding MGDG synthase and DGDG synthase were isolated (for reviews see Ref. 6 and Footnote 2). In Arabidopsis thaliana, three genes (MGD1, MGD2, MGD3) are known encoding MGDG synthases. The corresponding enzymes transfer a galactose moiety from UDP-galactose to diacylglycerol (8 -11). The synthesis of DGDG in plants is assumed to involve the galactosylation of MGDG by the galactolipid: galactolipid galactosyltransferase (EC 2.4

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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DGD2, an Arabidopsis Gene Encoding a UDP-Galactose-dependent Digalactosyldiacylglycerol Synthase Is Expressed during Growth under Phosphate-limiting Conditions

Kelly

Dörmann

2002

Journal of Biological Chemistry

173

125

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“…Furthermore, membranes are critical for subcellular compartmentation in eukaryotic cells (i.e., the establishment of organellar structures such as the nucleus, mitochondria, and chloroplasts). In contrast to animals and yeast, in which phospholipids are very abundant, plants contain high amounts of glycolipids, which carry a sugar moiety in the head group (Browse and Somerville, 1994;Vijayan et al, 1998). The sulfolipid sulfoquinovosyldiacylglycerol (SQDG) and the two galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are present in all higher plants and are particularly enriched in chloroplasts (Joyard et al, 1998;Dörmann and Benning, 2002).…”

Section: Introductionmentioning

confidence: 99%

Disruption of the Two Digalactosyldiacylglycerol Synthase Genes DGD1 and DGD2 in Arabidopsis Reveals the Existence of an Additional Enzyme of Galactolipid Synthesis

2003

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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.

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Photoprotection of Photosystem II: Reaction Center Quenching Versus Antenna Quenching

Hüner

Ivanov

Sane

et al. 2008

Photoprotection, Photoinhibition, Gene Regulation, and Environment

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A Genetic Approach to Investigating Membrane Lipid Structure and Photosynthetic Function

Cited by 11 publications

References 83 publications

DGD2, an Arabidopsis Gene Encoding a UDP-Galactose-dependent Digalactosyldiacylglycerol Synthase Is Expressed during Growth under Phosphate-limiting Conditions

DGD2, an Arabidopsis Gene Encoding a UDP-Galactose-dependent Digalactosyldiacylglycerol Synthase Is Expressed during Growth under Phosphate-limiting Conditions

Disruption of the Two Digalactosyldiacylglycerol Synthase Genes DGD1 and DGD2 in Arabidopsis Reveals the Existence of an Additional Enzyme of Galactolipid Synthesis

Photoprotection of Photosystem II: Reaction Center Quenching Versus Antenna Quenching

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