Fatty Acid Synthesis in Pea Root Plastids Is Inhibited by the Action of Long-Chain Acyl-Coenzyme as on Metabolite Transporters

• Published in: Plant physiology (Bethesda) Vol. 126; no. 3; pp. 1259 - 1265
• Main Authors: Simon R. Fox, Stephen Rawsthorne, Hills, Matthew J.
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.07.2001; American Society of Plant Physiologists
• Subjects: Acetates; Acyl Coenzyme A - pharmacology; Adenosine Triphosphate - metabolism; Agronomy. Soil science and plant productions; Biochemical Processes and Macromolecular Structures; Biological and medical sciences; Biological Transport; Brassica; Economic plant physiology; Energy Metabolism; Fatty acids; Fatty Acids - biosynthesis; Fundamental and applied biological sciences. Psychology; Glucose-6-Phosphate - metabolism; Hexoses - metabolism; In Vitro Techniques; Lipid metabolism; Metabolism; Metabolism. Physicochemical requirements; Nitrogen metabolism and other ones (excepting carbon metabolism); Nutrition. Photosynthesis. Respiration. Metabolism; Oilseeds; Peas; Pisum sativum - drug effects; Pisum sativum - metabolism; Plant physiology and development; Plant roots; Plant Roots - metabolism; Plants; Plastics - metabolism; Plastids; Silicones; Starch - metabolism; Starches; Brassica napus var. oleifera; Root; Interspecific comparison; Biological transport; Lipids; Biosynthesis; Plastid; Metabolism; Fatty acids; Oil plant(vegetal); Grain legume; Regulation(control); Leguminosae; Cruciferae; Dicotyledones; Pisum sativum; Angiospermae; Pentose phosphate pathway; Carbohydrate; Spermatophyta; Inhibition; ATP; Carrier protein
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.126.3.1259

The uptake in vitro of glucose (Glc)-6-phosphate (Glc-6-P) into plastids from the roots of 10- to 14-d-old pea (Pisum sativum L. cv Puget) plants was inhibited by oleoyl-coenzyme A (CoA) concentrations in the low micromolar range (1-2 μM). The IC50 (the concentration of inhibitor that reduces enzyme activity by 50%) for the inhibition of Glc-6-P uptake was approximately 750 nM; inhibition was reversed by recombinant rapeseed (Brassica napus) acyl-CoA binding protein. In the presence of ATP (3 mM) and CoASH (coenzyme A; 0.3 mM), Glc-6-P uptake was inhibited by 60%, due to long-chain acyl-CoA synthesis, presumably from endogenous sources of fatty acids present in the preparations. Addition of oleoyl-CoA (1 μM) decreased carbon flux from Glc-6-P into the synthesis of starch and through the oxidative pentose phosphate (OPP) pathway by up to 73% and 40%, respectively. The incorporation of carbon from Glc-6-P into fatty acids was not detected under any conditions. Oleoyl-CoA inhibited the incorporation of acetate into fatty acids by 67%, a decrease similar to that when ATP was excluded from incubations. The oleoyl-CoA-dependent inhibition of fatty acid synthesis was attributable to a direct inhibition of the adenine nucleotide translocator by oleoyl-CoA, which indirectly reduced fatty acid synthesis by ATP deprivation. The Glc-6-P-dependent stimulation of acetate incorporation into fatty acids was reversed by the addition of oleoyl-CoA.