Diacylglycerol acyltransferase in maturing safflower seeds: its influences on the fatty acid composition of triacylglycerol and on the rate of triacylglycerol synthesis

Ichihara, Kazuo; Takahashi, Toshiaki; Fujii, Shoji

doi:10.1016/0005-2760(88)90253-6

Cited by 98 publications

(58 citation statements)

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“…In Arabidopsis seedlings, Glc and ABA actively regulate the transcription of ACYL-COENZYME A:DIACYLGLYCEROL ACYLTRANSFERASE1 (DGAT1), which is crucial for TAG biosynthesis (Lu et al, 2003), although the exact molecular mechanism has not been determined. DGAT1, which catalyzes the final acylation step of sn-1,2-diacylglycerol to TAG, is thought to be the ratelimiting enzyme of TAG biosynthesis (Ichihara et al, 1988). Arabidopsis dgat1 mutant seeds only accumulate about 55% to 75% of TAG (Routaboul et al, 1999;Zou et al, 1999;Kaup et al, 2002), whereas seedspecific overexpression of DGAT1 increases oil content from 11% to 28% (Jako et al, 2001;Taylor et al, 2009;Andrianov et al, 2010).…”

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ABI4 Activates DGAT1 Expression in Arabidopsis Seedlings during Nitrogen Deficiency

et al. 2011

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Triacylglycerol (TAG) is the major seed storage lipid and is important for biofuel and other renewable chemical uses. Acylcoenzyme A:diacylglycerol acyltransferase1 (DGAT1) is the rate-limiting enzyme in the TAG biosynthesis pathway, but the mechanism of its regulation is unknown. Here, we show that TAG accumulation in Arabidopsis (Arabidopsis thaliana) seedlings increased significantly during nitrogen deprivation (0.1 mM nitrogen) with concomitant induction of genes involved in TAG biosynthesis and accumulation, such as DGAT1 and OLEOSIN1. Nitrogen-deficient seedlings were used to determine the key factors contributing to ectopic TAG accumulation in vegetative tissues. Under low-nitrogen conditions, the phytohormone abscisic acid plays a crucial role in promoting TAG accumulation in Arabidopsis seedlings. Yeast one-hybrid and electrophoretic mobility shift assays demonstrated that ABSCISIC ACID INSENSITIVE4 (ABI4), an important transcriptional factor in the abscisic acid signaling pathway, bound directly to the CE1-like elements (CACCG) present in DGAT1 promoters. Genetic studies also revealed that TAG accumulation and DGAT1 expression were reduced in the abi4 mutant. Taken together, our results indicate that abscisic acid signaling is part of the regulatory machinery governing TAG ectopic accumulation and that ABI4 is essential for the activation of DGAT1 in Arabidopsis seedlings during nitrogen deficiency.

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ABI4 Activates DGAT1 Expression in Arabidopsis Seedlings during Nitrogen Deficiency

et al. 2011

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“…A number of studies with both mammalian (Mayorek et al, 1989;Tijburg et al, 1989) and plant (Ichihara et al, 1988;Harwood, 1993a, 1993b;Settlage et al, 1995;Perry et al, 1999) systems have suggested that DGAT may catalyze a rate-limiting reaction in TAG bioassembly. For example, developing seeds of B. napus L., cv Shiralee, have been shown to produce significant levels of DAG during the active phase of oil accumulation Harwood, 1993a, 1993b).…”

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Seed-Specific Over-Expression of an Arabidopsis cDNA Encoding a Diacylglycerol Acyltransferase Enhances Seed Oil Content and Seed Weight

et al. 2001

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We recently reported the cloning and characterization of an Arabidopsis (ecotype Columbia) diacylglycerol acyltransferase cDNA (Zou et al., 1999) and found that in Arabidopsis mutant line AS11, an ethyl methanesulfonate-induced mutation at a locus on chromosome II designated as Tag1 consists of a 147-bp insertion in the DNA, which results in a repeat of the 81-bp exon 2 in the Tag1 cDNA. This insertion mutation is correlated with an altered seed fatty acid composition, reduced diacylglycerol acyltransferase (DGAT; EC 2.3.1.20) activity, reduced seed triacylglycerol content, and delayed seed development in the AS11 mutant. The effect of the insertion mutation on microsomal acyl-coenzyme A-dependent DGAT is examined with respect to DGAT activity and its substrate specificity in the AS11 mutant relative to wild type. We demonstrate that transformation of mutant AS11 with a single copy of the wild-type Tag1 DGAT cDNA can complement the fatty acid and reduced oil phenotype of mutant AS11. More importantly, we show for the first time that seed-specific over-expression of the DGAT cDNA in wild-type Arabidopsis enhances oil deposition and average seed weight, which are correlated with DGAT transcript levels. The DGAT activity in developing seed of transgenic lines was enhanced by 10% to 70%. Thus, the current study confirms the important role of DGAT in regulating the quantity of seed triacylglycerols and the sink size in developing seeds.

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“…In oil seeds, the first and third acyltransferase enzymes, glycerol-3-P AT and DAG-AT, were studied by various workers (3,4,7,10,12,15). These studies show that, in general, glycerol-3-P AT preferentially uses palmitoyl CoA over C-18 CoAs (7,8,10).…”

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Lysophosphatidate Acyltransferase Activities in the Microsomes from Palm Endosperm, Maize Scutellum, and Rapeseed Cotyledon of Maturing Seeds

Huang²

1989

Plant Physiol.

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Lysophosphatidate (LPA) acyltransferase (EC 2.3.1.51) in the microsomes from palm endosperm (Syagrus cocoides Martius), maize scutellum (Zea mays L.), and rapeseed cotyledon (Brassica napus L.) of maturing seeds were studied for their specificities toward the acyl moiety of the substrates lysophosphatidate and acyl coenzyme A (CoA). The LPA acceptor greatly influenced the acyl CoA specificity of the enzyme and vice versa. With 1-oleoyllysophosphatidate (LPA-18:1), the palm enzyme was equally active on oleoyl CoA and lauroyl CoA, whereas the maize and rapeseed enzymes were more active on oleoyl CoA than on lauroyl CoA. With 1-lauroyl-lysophosphatidate (LPA-12), which generated less activity than LPA-18:1, the palm enzyme was three times more active on lauroyl CoA than on oleoyl CoA. LPA-12 was an inactive substrate for the maize and rapeseed enzymes. The selectivity of the enzymes was also studied using a mixture of LPA-18:1 and LPA-12, as well as lauroyl CoA and oleoyl CoA. Under this selectivity condition and compared to the specificity condition, the enzymes from all the three seeds exerted stronger preference for oleoyl moiety in either the LPA or acyl CoA, and again, only the palm enzyme could act on LPA-12.Similar studies, although in lesser detail, showed that the enzymes from soybean and castor bean were similar to the maize and rapeseed enzymes in having little activity on substrates containing lauroyl moiety. The results demonstrate the importance of the acyl group in the sn-I position of LPA in determining the acyl preference in the sn-2 position in phosphatidate synthesis. The palm enzyme appears to be the only one capable of synthesizing phosphatidates containing high amounts of lauric moieties.In oil seeds, TAG3 synthesis proceeds via the Kennedy pathway (20). Glycerol-3-P is first acylated by glycerol-3-P AT at the sn-l position to form lysophosphatidate, which undergoes a second acylation by LPA-AT to form phosphatidate.

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Diacylglycerol acyltransferase in maturing safflower seeds: its influences on the fatty acid composition of triacylglycerol and on the rate of triacylglycerol synthesis

Cited by 98 publications

References 16 publications

ABI4 Activates DGAT1 Expression in Arabidopsis Seedlings during Nitrogen Deficiency

ABI4 Activates DGAT1 Expression in Arabidopsis Seedlings during Nitrogen Deficiency

Seed-Specific Over-Expression of an Arabidopsis cDNA Encoding a Diacylglycerol Acyltransferase Enhances Seed Oil Content and Seed Weight

Lysophosphatidate Acyltransferase Activities in the Microsomes from Palm Endosperm, Maize Scutellum, and Rapeseed Cotyledon of Maturing Seeds

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