Inhibition by long-chain acyl-CoAs of glucose 6-phosphate metabolism in plastids isolated from developing embryos of oilseed rape (Brassica napus L.)

Johnson, Philip E.; Fox, Simon R.; Hills, Matthew J.; Rawsthorne, Stephen

doi:10.1042/bj3480145

Cited by 19 publications

(23 citation statements)

References 19 publications

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“…The massive output of these saturated fatty acids from the plastid could produce a temporary starvation/lack of ACBPs in the cytoplasm, the accumulation of free acylCoAs, the inhibition of glucose 6-P input in the plastid (Johnson et al 2000) and,…”

Section: Lipids Changes In Transgenic Arabidopsis Seedsmentioning

confidence: 99%

Effect of a mutagenized acyl-ACP thioesterase FATA allele from sunflower with improved activity in tobacco leaves and Arabidopsis seeds

Moreno‐Pérez

Venegas-Calerón

Vaistij

et al. 2013

Planta

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Acyl-acyl carrier protein (ACP) thioesterases hydrolyze plastid-localised acyl-ACP intermediates and make possible the export of acyl moieties to the cytosol for their incorporation into glycerolipids. The substrate specificity of the acyl-ACP thioesterases importantly determine the type of fatty acids that are exported from plastids. Thus, designing acyl-ACP thioesterases with different substrate specificities or kinetic properties would be of interest for plant lipid biotechnology to produce oils enriched in specialty fatty acids. Although they have not been yet crystallized, their tertiary structures have been modelled by comparison with other enzymes catalyzing similar reactions, suggesting candidate amino acid residues involved in substrate specificity. In the present work, the FatA thioesterase from Helianthus annuus was used to test the impact of changes in the amino acids present in the binding pocket on substrate specificity and catalytic efficiency. Amongst all the mutated enzymes studied, Q215W was especially interesting as it had higher specificity towards saturated acyl-ACP substrates and higher catalytic efficiency compared to wild type H. annuus FatA. Null, wild type and high-efficiency alleles were transiently expressed in tobacco leaves to check their effect on lipid biosynthesis. Expression of active FatA thioesterases altered the composition of leaf triacylglycerols but did not altered total lipid content. However, the expression of the wild type and the high efficiency alleles in Arabidopsis thaliana transgenic seeds resulted in a strong reduction in oil content and an increase in total saturated fatty acid content. The role and influence of acyl-ACP thioesterases in plant metabolism and their possible applications in lipid biotechnology are discussed.

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Section: Lipids Changes In Transgenic Arabidopsis Seedsmentioning

confidence: 99%

Effect of a mutagenized acyl-ACP thioesterase FATA allele from sunflower with improved activity in tobacco leaves and Arabidopsis seeds

Moreno‐Pérez

Venegas-Calerón

Vaistij

et al. 2013

Planta

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“…Fatty acids were saponified in 1 ml of 15 % (w\v) KOH in methanol at 80 mC for 40 min, acidified with 6 M HCl and extracted twice into an equal volume of chloroform. The organic phase was concentrated and the fatty acids were purified by TLC and quantified by scintillation counting as described previously [6].…”

Section: Silicone Oil Centrifugation and Measurement Of Glc6p Uptakementioning

confidence: 99%

“…The overall rates of fatty acid synthesis in plastids from carbon derived from Glc6P were 3-4-fold lower in the presence of CoA (0.1-0.3 mM) and ATP (3 mM) [6,8]. The inhibition caused by these concentrations of CoA was alleviated by acyl-CoA binding protein (ACBP).…”

Section: Introductionmentioning

confidence: 99%

“…ACBPs have been shown to be present in all plant tissues examined including developing oilseed rape seeds [15,16]. The inhibition by CoA and ATP [6,8] provides indirect evidence that the presence of acyl-CoA thioesters can in some way affect the rate of fatty acid synthesis in the plastids. Overall, these previous studies provided strong support for the hypothesis that it was the accumulation of lcACoAs from de no o fatty acid synthesis, which was responsible for feedback inhibition of the transporter proteins located on the plastid envelope.…”

Section: Introductionmentioning

confidence: 99%

“…and stearic acid (C ") : ! ) [6]. These carbon precursors include -glucose 6-phosphate (Glc6P), malate, pyruvate, dihydroxyacetone phosphate and acetate [5,7].…”

Section: Introductionmentioning

confidence: 99%

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Inhibition of the glucose-6-phosphate transporter in oilseed rape (Brassica napus L.) plastids by acyl-CoA thioesters reduces fatty acid synthesis

Fox

Hill

Rawsthorne

et al. 2000

Biochemical Journal

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Addition of oleoyl-CoA (1µM), or other acyl-CoA thioesters with a chain length of C16 or greater, to oilseed rape plastids (Brassica napus L.) inhibited the rate of D-glucose 6-phosphate (Glc6P) uptake by 70% after 2min. The IC50 value for oleoyl-CoA inhibition of the transporter was approx. 0.2–0.3µM. Inhibition was alleviated by the addition of acyl-CoA binding protein (ACBP) or BSA at slightly higher concentrations. Oleic acid (5–25µM), Tween 40 (10µM), Triton-X 100 (10µM) and palmitoylcarnitine (5µM) had no effect on Glc6P uptake. The uptake of [1-14C]Glc6P occurred in exchange for Pi, 3-phosphoglycerate or Glc6P at a typical rate of 30nmol Glc6P/min per unit of glyceraldehyde-3-phosphate dehydrogenase (NADP+). The Km(app) of the Glc6P transporter for Glc6P was 100µM. Neither CoA (0.3mM) nor ATP (3mM) inhibited Glc6P uptake, but the transporter was inhibited by 72% when ATP and CoA were added together. This inhibition was attributable to the synthesis of acyl-CoA thioesters, predominantly oleoyl-CoA and palmitoyl-CoA, by long-chain fatty acid-CoA ligase (EC 6.2.1.3) from endogenous fatty acids in the plastid preparations. Acyl-CoA thioesters did not inhibit the uptake of [2-14C]pyruvate or D-[1-14C]glucose into plastids. In vivo quantities of oleoyl-CoA and other long-chain acyl-CoA thioesters were lower than those for ACBP in early cotyledonary embryos, 0.7±0.2pmol/embryo and 2.2±0.2pmol/embryo respectively, but in late cotyledonary embryos quantities of long-chain acyl-CoA thioesters were greater than ACBP, 3±0.4pmol/embryo and 1.9±0.2pmol/embryo respectively.

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Plastid Metabolic Pathways

Tetlow

Rawsthorne

Raines

et al. 2018

Annual Plant Reviews Online

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Inhibition by long-chain acyl-CoAs of glucose 6-phosphate metabolism in plastids isolated from developing embryos of oilseed rape (Brassica napus L.)

Cited by 19 publications

References 19 publications

Effect of a mutagenized acyl-ACP thioesterase FATA allele from sunflower with improved activity in tobacco leaves and Arabidopsis seeds

Effect of a mutagenized acyl-ACP thioesterase FATA allele from sunflower with improved activity in tobacco leaves and Arabidopsis seeds

Inhibition of the glucose-6-phosphate transporter in oilseed rape (Brassica napus L.) plastids by acyl-CoA thioesters reduces fatty acid synthesis

Plastid Metabolic Pathways

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