Does triacylglycerol biosynthesis require diacylglycerol acyltransferase (DAGAT)?
Microsomal membrane preparations from the developing seeds of sunflower (Helianthus annuus L.) catalyse the conversion of sn-glycerol-3-phosphate and acyl-CoA to triacylglycerol via phosphatidic acid and diacylglycerol. The formation of diacylglycerol from phosphatidic acid was Mg2+ dependent and in the presence of EDTA phosphatidic acid accumulated. This property was used to generate large quantities of endogenous radioactive phosphatidic acid in the membranes. On addition of Mg2+ the phosphatidic acid was used in triacylglycerol formation. Acyl-CoA had little effect on the label which accumulated in triacylglycerol from phosphatidic acid. Diacylglycerol acyltransferase, therefore, may not play a major role in oil formation as originally envisaged and other enzymes, including diacylglycerol:diacylglycerol transacylase [Stobart, Mancha, Lenman, Dahlqvist and Stymne (1997) Planta 203, 58-66] may have important biosynthetic functions.
Fraser
T
T
School of Biological Sciences, University of Bristol, Woodlands Road, Bristol BS8 1UG, UK. t.c.m.fraser@bristol.ac.uk
Waters
A
A
Chatrattanakunchai
S
S
Stobart
K
K
D000214:Acyl Coenzyme A / Q000494:pharmacology; D000217:Acyltransferases / Q000378:metabolism*; D002250:Carbon Radioisotopes; D051048:Diacylglycerol O-Acyltransferase; D004492:Edetic Acid / Q000494:pharmacology; D005994:Glycerophosphates / Q000378:metabolism; D006368:Helianthus / Q000201:enzymology*; D007425:Intracellular Membranes / Q000201:enzymology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology; D012639:Seeds / Q000201:enzymology; D014280:Triglycerides / Q000096:biosynthesis*
D000214:Acyl Coenzyme A; D002250:Carbon Radioisotopes; D005994:Glycerophosphates; D014280:Triglycerides; C017585:oleoyl-coenzyme A; D004492:Edetic Acid; D000217:Acyltransferases; D051048:Diacylglycerol O-Acyltransferase; D008274:Magnesium