Inhibition of the glucose-6-phosphate transporter in oilseed rape (Brassica napus L.) plastids by acyl-CoA thioesters reduces fatty acid synthesis
Inhibition of the glucose-6-phosphate transporter in oilseed rape (Brassica napus L.) plastids by acyl-CoA thioesters reduces fatty acid synthesis
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DOI：
10.1042/0264-6021:3520525
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发表时间：
2000-12-01
影响因子：
4.1
通讯作者：
Hills, MJ
中科院分区：
文献类型：
--
作者：
Fox, SR;Hill, LM;Hills, MJ
将油酰-CoA（1 μ M）或其它具有C（16）或更长链长的酰基-CoA硫酯添加到油菜质体（甘蓝型油菜L.）在2分钟后抑制D-葡萄糖6-磷酸（Glc 6P）摄取速率70%。0.2-0.3 μ M。通过添加稍高浓度的酰基辅酶A结合蛋白（ACBP）或BSA减轻抑制。油酸（5-25 μ M）、吐温40（10 μ M）、Triton-X 100（10 μ M）和棕榈酰肉碱（5 μ M）对Glc 6P摄取没有影响。[1-（14）C] Glc 6P的摄取以每单位甘油醛-3-磷酸脱氢酶（NADP（+））30 nmol Glc 6P/min的典型速率交换P（i）、3-磷酸甘油酸或Glc 6P。Glc 6P转运蛋白对Glc 6P的K（m（app））为100 μ M。也不是CoA。(0.3 ATP（3 mM）也不抑制Glc 6P摄取，但当ATP和CoA一起加入时，转运体被抑制72%。这种抑制作用归因于长链脂肪酸-CoA连接酶（EC 6.2.1.3）从质体制剂中的内源性脂肪酸合成酰基-CoA硫酯，主要是油酰-CoA和棕榈酰-CoA。酰基-CoA硫酯不抑制[2-（14）C]丙酮酸或D-[1-（14）C]葡萄糖进入质体的摄取。在早期子叶胚中，油酰-CoA和其他长链酰基-CoA硫酯的体内量低于ACBP的量，分别为0.7 +/- 0.2 pmol/胚和2.2 +/- 0.2 pmol/胚，但在晚期子叶胚中，长链酰基-CoA硫酯的量大于ACBP，3 +/- 0.4 pmol/胚胎和1.9 +/- 0.2 pmol/胚胎。
Addition of oleoyl-CoA (1 muM), or other acyl-CoA thioesters with a chain length of C(16) or greater, to oilseed rape plastids (Brassica napus L.) inhibited the rate of D-glucose 6-phosphate (Glc6P) uptake by 70 % after 2 min. The IC(50) value for oleoyl-CoA inhibition of the transporter was approx. 0.2-0.3 muM. Inhibition was alleviated by the addition of acyl-CoA binding protein (ACBP) or BSA at slightly higher concentrations. Oleic acid (5-25 muM), Tween 40 (10 muM), Triton-X 100 (10 muM) and palmitoylcarnitine (5 muM) had no effect on Glc6P uptake. The uptake of [1-(14)C]Glc6P occurred in exchange for P(i), 3-phosphoglycerate or Glc6P at a typical rate of 30 nmol Glc6P/min per unit of glyceraldehyde-3-phosphate dehydrogenase (NADP(+)). The K(m(app)) of the Glc6P transporter for Glc6P was 100 muM. Neither CoA. (0.3 mM) nor ATP (3 mM) 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-(14)C]pyruvate or D-[1-(14)C]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 +/- 0.2 pmol/embryo and 2.2 +/- 0.2 pmol/embryo respectively, but in late cotyledonary embryos quantities of long-chain acyl-CoA thioesters were greater than ACBP, 3 +/- 0.4 pmol/embryo and 1.9 +/- 0.2 pmol/embryo respectively.