A 25-Amino Acid Sequence of the Arabidopsis TGD2 Protein Is Sufficient for Specific Binding of Phosphatidic Acid

Lu, Binbin; Benning, Christoph

doi:10.1074/jbc.m109.016014

Cited by 65 publications

(80 citation statements)

References 31 publications

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“…The cDNAs from Arabidopsis DGD1, DGD2, and Chloroflexus GlcT (5,8,15,19,20,45,46) were cloned into E. coli expression vectors for lipid measurements and lipid binding or liposome aggregation experiments (31,47) or into binary vectors (48) for Arabidopsis transformation (SI Appendix, SI Material and Methods). The Arabidopsis dgd1-1 mutant was transformed using the Agrobacterium floraldip method (49).…”

Section: Methodsmentioning

confidence: 99%

Synthesis and transfer of galactolipids in the chloroplast envelope membranes of Arabidopsis thaliana

Kelly

Kalisch

Hölzl

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Galactolipids [monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG)] are the hallmark lipids of photosynthetic membranes. The galactolipid synthases MGD1 and DGD1 catalyze consecutive galactosyltransfer reactions but localize to the inner and outer chloroplast envelopes, respectively, necessitating intermembrane lipid transfer. Here we show that the N-terminal sequence of DGD1 (NDGD1) is required for galactolipid transfer between the envelopes. Different diglycosyllipid synthases (DGD1, DGD2, and Chloroflexus glucosyltransferase) were introduced into the dgd1-1 mutant of Arabidopsis in fusion with N-terminal extensions (NDGD1 and NDGD2) targeting to the outer envelope. Reconstruction of DGDG synthesis in the outer envelope membrane was observed only with diglycosyllipid synthase fusion proteins carrying NDGD1, indicating that NDGD1 enables galactolipid translocation between envelopes. NDGD1 binds to phosphatidic acid (PA) in membranes and mediates PA-dependent membrane fusion in vitro. These findings provide a mechanism for the sorting and selective channeling of lipid precursors between the galactolipid pools of the two envelope membranes.galactolipid | chloroplast | envelope | lipid transfer T he two galactolipids, monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), are most abundant in land plants, green algae, and cyanobacteria (1). MGDG and DGDG are predominant in thylakoid membranes of chloroplasts, where they are integral components of photosystems I and II and of the light-harvesting complex II (2-4), and are essential for photosynthesis and growth (5, 6). Galactolipids are synthesized in the envelope membranes of chloroplasts (7). In tobacco and Arabidopsis, the MGDG synthase MGD1 localizes to the inner envelope where it produces the major proportion of MGDG (8, 9). The outer chloroplast envelope of Arabidopsis harbors two DGDG synthases, DGD1 and DGD2 (10, 11). DGD1 synthesizes the predominant proportion of DGDG, whereas DGD2 is active during growth under phosphate limitation. Phosphate deprivation results in the accumulation of glycolipids, including DGDG, at the expense of phospholipids and the redirection of phosphate to other cellular processes (12). DGDG synthesized by DGD1 and DGD2 is transported to thylakoid and extraplastidial membranes, respectively (11,12).Transport processes are required to channel lipid molecules between organelles and across and between different membranes (13). An ATP-binding cassette (ABC) transporter composed of three different subunits [trigalactosyldiacylglycerol1 (TGD1), -2 (TGD2), and -3 (TGD3)] is involved in the transfer of lipid precursors from the endoplasmic reticulum (ER) to the chloroplast where they are used for galactolipid synthesis. Galactolipid molecules derived from imported precursors can be distinguished from galactolipids directly synthesized in the chloroplast by the acyl composition at the sn2 position of the glycerol, with molecules containing sn2-16C acyl groups being chloroplast-derived (prokaryotic...

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Section: Methodsmentioning

confidence: 99%

Synthesis and transfer of galactolipids in the chloroplast envelope membranes of Arabidopsis thaliana

Kelly

Kalisch

Hölzl

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…The efficiency of the cDNA synthesis was assessed by real-time PCR amplification of a control gene encoding UBQ10 (At4g05320). cDNAs were then diluted to yield similar threshold cycle (Ct) values (20) based on the Ct of the UBQ10. The level of individual gene expression was normalized to that of UBQ10 by subtracting the Ct value of UBQ10 from the tested genes.…”

Section: Methodsmentioning

confidence: 99%

“…PA has been reported to bind to various proteins, including transcriptional factors, protein kinases, lipid kinases, protein phosphatases, and proteins involved in vesicular trafficking and cytoskeletal rearrangement (1). Several PA-interacting proteins have been identified in plants, including ABI1, PDK1, CTR1, TGD2, and NADPH oxidase (8,10,18,19,20). Additional PAbinding proteins were isolated by PA-affinity chromatography followed by mass spectrometric analysis (21).…”

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confidence: 99%

Phosphatidic Acid Binds and Stimulates Arabidopsis Sphingosine Kinases

Guo

Mishra

Taylor

et al. 2011

Journal of Biological Chemistry

107

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Phosphatidic acid (PA) and phytosphingosine-1-phosphate (phyto-S1P) have both been identified as lipid messengers mediating plant response to abscisic acid (ABA). To determine the relationship of these messengers, we investigated the direct interaction of PA with Arabidopsis sphingosine kinases (SPHKs) that phosphorylate phytosphingosine to generate phyto-S1P. Two unique SPHK cDNAs were cloned from the annotated At4g21540 locus of Arabidopsis, and the two transcripts are differentially expressed in Arabidopsis tissues. Both SPHKs are catalytically active, phosphorylating various longchain sphingoid bases (LCBs) and are associated with the tonoplast. Phosphatidic acid (PA) 4 has emerged as a class of pivotal lipid messengers in cell growth, development, and stress responses, and the regulatory functions of PA are being established in plants, animals, and fungi (1-3). PA is a minor membrane lipid, constituting less than 1% of total phospholipids in most plant tissues (4). However, the cellular level of PA in plants is dynamic, increasing rapidly under various conditions, including chilling, freezing, wounding, pathogen elicitation, dehydration, salt, nutrient starvation, nodule induction, and oxidative stress (1, 2, 5, 6). The functional significance of PA has been indicated by characterization of various phospholipase Ds (PLD) that produce regulatory PA and by measurements of PA changes under different stress conditions (1, 2). Characterization of genetic ablations, together with biochemical analyses, has shown that different PLDs have unique functions (1, 7). The differential activation, expression, and cellular locales, as well as substrate preferences of PLDs, indicate that the cellular location and timing of PA production are important determinants of PA function.A series of recent results have provided mechanistic insights into how specific PLD and PA mediate the abscisic acid (ABA) promotion of stomatal closure in Arabidopsis (8, 9). Recently, PLD␣1 and PA were found to regulate NADPH oxidase activity and the production of reactive oxygen species (ROS) in ABAmediated stomatal closure (10). In addition to PA, another lipid messenger, long-chain base-1-phosphate (LCBP) including sphingosine-1-phosphate (S1P) and phyto-S1P has been found to promote the ABA effect on stomatal closure (11-13). Arabidopsis sphingosine kinase (SPHK) activity was mainly associated with the membrane fraction (13). Recent study suggests that sphingosine and S1P are not detectable in Arabidopsis leaves due to the lack of expression of sphingolipid ⌬4-desaturase, indicating that sphingosine and S1P are unlikely to play a significant role in ABA-mediated stomatal closure (14). However, knock-out of Arabidopsis SPHK1 rendered the stomatal closure less sensitive to ABA, whereas overexpression of SPHK1 increased stomatal closure and ABA sensitivity (15). These results suggest that other LCBPs are involved in ABA signaling in Arabidopsis (16). Phytosphingosine is one of such LCBs in Arabidopsis leaves and its phosphorylated form, phyto-S1...

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“…The functionality of mce domains as phosphatidic acid binding domain seems to have been conserved across different families-the Arabidopsis chloroblast protein Tgl2, which contains only one mce domain, also binds PA albeit with lower affinity. 23 We hypothesize that the duplication of mce domains in MAM7 leads to an acquisition of an entirely new functionality, the capability to bind to fibronectin. By enabling pathogens to establish interactions with two distinct types of host cell receptors, pathogens have increased their capacity for initial attachment.…”

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confidence: 99%