Analysis of Acyl Fluxes through Multiple Pathways of Triacylglycerol Synthesis in Developing Soybean Embryos
Year: 2009
Type: article
Abstract: The reactions leading to triacylglycerol (TAG) synthesis in oilseeds have been well characterized. However, quantitative analyses of acyl group and glycerol backbone fluxes that comprise extraplastidic phospholipid and TAG synthesis, including acyl editing and phosphatidylcholine-diacylglycerol interconversion, are lacking. To investigate these fluxes, we rapidly labeled developing soybean (Glycine max) embryos with [(14)C]acetate and [(14)C]glycerol. Cultured intact embryos that mimic in planta growth were used. The initial kinetics of newly synthesized acyl chain and glycerol backbone incorporation into phosphatidylcholine (PC), 1,2-sn-diacylglycerol (DAG), and TAG were analyzed along with their initial labeled molecular species and positional distributions. Almost 60% of the newly synthesized fatty acids first enter glycerolipids through PC acyl editing, largely at the sn-2 position. This flux, mostly of oleate, was over three times the flux of nascent [(14)C]fatty acids incorporated into the sn-1 and sn-2 positions of DAG through glycerol-3-phosphate acylation. Furthermore, the total flux for PC acyl editing, which includes both nascent and preexisting fatty acids, was estimated to be 1.5 to 5 times the flux of fatty acid synthesis. Thus, recycled acyl groups (16:0, 18:1, 18:2, and 18:3) in the acyl-coenzyme A pool provide most of the acyl chains for de novo glycerol-3-phosphate acylation. Our results also show kinetically distinct DAG pools. DAG used for TAG synthesis is mostly derived from PC, whereas de novo synthesized DAG is mostly used for PC synthesis. In addition, two kinetically distinct sn-3 acylations of DAG were observed, providing TAG molecular species enriched in saturated or polyunsaturated fatty acids.
Source: PLANT PHYSIOLOGY
Institution: Michigan State University
Language: English
Subfield: Biochemistry
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,851
Funders: U.S. Department of Energy, U.S. Department of Agriculture, Michigan State University, Office of Science, College of Engineering, Michigan State University, Cooperative State Research, Education, and Extension Service, Great Lakes Bioenergy Research Center, Biological and Environmental Research
Awards: GREAT LAKES BIOENERGY RESEARCH CENTER, G1592975470, BIOSYNTHESIS OF TRIACYLGLYCEROL IN DEVELOPING OIL SEEDS, G222180108, G222768804, BIOSYNTHESIS OF TRIACYLGLYCEROL IN DEVELOPING OIL SEEDS, G3193070969, GREAT LAKES BIOENERGY RESEARCH CENTER, TAS::89 0227:: TAS RECOVERY ACT - BIOENERGY RESEARCH CENTER CAPITAL EQUIPMENT - GLBRC, TAS::89 0227:: TAS RECOVERY ACT - BIOENERGY RESEARCH CENTER CAPITAL EQUIPMENT - GLBRC
OpenAlex ID: W2150179956