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Plant Physiology logoLink to Plant Physiology
. 1996 Mar;110(3):923–931. doi: 10.1104/pp.110.3.923

Cholinephosphotransferase and Diacylglycerol Acyltransferase (Substrate Specificities at a Key Branch Point in Seed Lipid Metabolism).

G Vogel 1, J Browse 1
PMCID: PMC157792  PMID: 12226231

Abstract

Many oilseed plants accumulate triacylglycerols that contain unusual fatty acyl structures rather than the common 16- and 18-carbon fatty acids found in membrane lipids of these plants. In vitro experiments demonstrate that triacylglycerols are synthesized via diacylglycerols in microsomal preparations and that this same sub-cellular fraction is the site for the synthesis of phosphatidylcholine, which in seeds is synthesized from diacylglycerol by CDP-choline: diacylglycerol cholinephosphotransferase. In microsomes from Cuphea lanceolata, a plant that accumulates fatty acids with 10 carbons and no double bonds (10:0) in its oil, the diacylglycerol acyltransferase exhibited 4-fold higher activity with 10:0/10:0 molecular species of diacylglycerol than with molecular species containing 18-carbon fatty acids. In castor bean (Ricinus communis), which accumulates oil containing ricinoleic acid, diricinoleoyldiacylglycerol was the favored substrate for triacylglycerol synthesis. In contrast to these modest specificities of the diacylglycerol acyltransferases, the cholinephosphotransferases from these plants and from safflower (Carthamus tinctorius) and rapeseed (Brassica napus) showed little or no specificity across a range of different diacylglycerol substrates. Consideration of these results and other data suggests that the targeting of unusual fatty acids to triacylglycerol synthesis and their exclusion from membrane lipids are not achieved on the basis of the diacylglycerol substrate specificities of the enzymes involved and may instead require the spatial separation of two different diacylglycerol pools.

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Selected References

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  1. Bafor M., Smith M. A., Jonsson L., Stobart K., Stymne S. Ricinoleic acid biosynthesis and triacylglycerol assembly in microsomal preparations from developing castor-bean (Ricinus communis) endosperm. Biochem J. 1991 Dec 1;280(Pt 2):507–514. doi: 10.1042/bj2800507. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bradford M. M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976 May 7;72:248–254. doi: 10.1016/0003-2697(76)90527-3. [DOI] [PubMed] [Google Scholar]
  3. Cao Y. Z., Huang A. H. Acyl coenzyme a preference of diacylglycerol acyltransferase from the maturing seeds of cuphea, maize, rapeseed, and canola. Plant Physiol. 1987 Jul;84(3):762–765. doi: 10.1104/pp.84.3.762. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Griffiths G., Stobart A. K., Stymne S. The acylation of sn-glycerol 3-phosphate and the metabolism of phosphatidate in microsomal preparations from the developing cotyledons of safflower (Carthamus tinctorius L.) seed. Biochem J. 1985 Sep 1;230(2):379–388. doi: 10.1042/bj2300379. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Hjelmstad R. H., Bell R. M. sn-1,2-diacylglycerol choline- and ethanolaminephosphotransferases in Saccharomyces cerevisiae. Mixed micellar analysis of the CPT1 and EPT1 gene products. J Biol Chem. 1991 Mar 5;266(7):4357–4365. [PubMed] [Google Scholar]
  6. Ichihara K., Takahashi T., Fujii S. Diacylglycerol acyltransferase in maturing safflower seeds: its influences on the fatty acid composition of triacylglycerol and on the rate of triacylglycerol synthesis. Biochim Biophys Acta. 1988 Jan 19;958(1):125–129. doi: 10.1016/0005-2760(88)90253-6. [DOI] [PubMed] [Google Scholar]
  7. Li X., Franceschi V. R., Okita T. W. Segregation of storage protein mRNAs on the rough endoplasmic reticulum membranes of rice endosperm cells. Cell. 1993 Mar 26;72(6):869–879. doi: 10.1016/0092-8674(93)90576-c. [DOI] [PubMed] [Google Scholar]
  8. Ohlrogge J. B. Design of New Plant Products: Engineering of Fatty Acid Metabolism. Plant Physiol. 1994 Mar;104(3):821–826. doi: 10.1104/pp.104.3.821. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Palade G. Intracellular aspects of the process of protein synthesis. Science. 1975 Aug 1;189(4200):347–358. doi: 10.1126/science.1096303. [DOI] [PubMed] [Google Scholar]
  10. Shore G. C., Tata J. R. Two fractions of rough endoplasmic reticulum from rat liver. II. Cytoplasmic messenger RNA's which code for albumin and mitochondrial proteins are distributed differently between the two fractions. J Cell Biol. 1977 Mar;72(3):726–743. doi: 10.1083/jcb.72.3.726. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Somerville C., Browse J. Plant lipids: metabolism, mutants, and membranes. Science. 1991 Apr 5;252(5002):80–87. doi: 10.1126/science.252.5002.80. [DOI] [PubMed] [Google Scholar]
  12. Stahl U., Banas A., Stymne S. Plant Microsomal Phospholipid Acyl Hydrolases Have Selectivities for Uncommon Fatty Acids. Plant Physiol. 1995 Mar;107(3):953–962. doi: 10.1104/pp.107.3.953. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Voelker T. A., Worrell A. C., Anderson L., Bleibaum J., Fan C., Hawkins D. J., Radke S. E., Davies H. M. Fatty acid biosynthesis redirected to medium chains in transgenic oilseed plants. Science. 1992 Jul 3;257(5066):72–74. doi: 10.1126/science.1621095. [DOI] [PubMed] [Google Scholar]
  14. Vogel G., Browse J. Preparation of radioactively labeled synthetic sn-1,2-diacylglycerols for studies of lipid metabolism. Anal Biochem. 1995 Jan 1;224(1):61–67. doi: 10.1006/abio.1995.1008. [DOI] [PubMed] [Google Scholar]

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