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

2000 ◽  
Vol 352 (2) ◽  
pp. 525 ◽  
Author(s):  
Simon R. FOX ◽  
Lionel M. HILL ◽  
Stephen RAWSTHORNE ◽  
Matthew J. HILLS
2000 ◽  
Vol 28 (6) ◽  
pp. 665-666 ◽  
Author(s):  
S. E. Kubis ◽  
S. Rawsthorne

The phosphoenolpyruvate transporter (PPT) is one of several important transporters for channelling carbon intermediates utilized for fatty acid synthesis and other plastidial pathways from the cytosol into the plastid. In this paper we show results on how the activity of the PPT changes between two important, physiologically different developmental stages of oilseed rape embryos.


2000 ◽  
Vol 352 (2) ◽  
pp. 525-532 ◽  
Author(s):  
Simon R. FOX ◽  
Lionel M. HILL ◽  
Stephen RAWSTHORNE ◽  
Matthew J. HILLS

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.


2013 ◽  
Vol 12 (6) ◽  
pp. 962-970 ◽  
Author(s):  
Gang XIAO ◽  
Zhen-qian ZHANG ◽  
Rui-yang LIU ◽  
Chang-fa YIN ◽  
Xian-meng WU ◽  
...  

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