Overexpression of 3-ketoacyl-acyl-carrier protein synthase IIIs in plants reduces the rate of lipid synthesis
Overexpression of 3-ketoacyl-acyl-carrier protein synthase IIIs in plants reduces the rate of lipid synthesis
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DOI：
10.1104/pp.125.2.1103
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发表时间：
2001-02-01
期刊：
影响因子：
7.4
通讯作者：
Jaworski, JG
中科院分区：
文献类型：
--
作者：
Dehesh, K;Tai, H;Jaworski, JG
从菠菜（Spinacia oleracea; So KAS III）中获得编码3-酮脂酰基-酰基-载体蛋白（ACP）合酶III（KAS III）的cDNA，从细萼距花（Cuphea hookeriana）中分离两个密切相关的KAS III克隆（Ch KAS III-1和Ch KAS III-2）。两种Ch KAS III在所有检查的组织中组成型表达。当在花椰菜花叶病毒-35S启动子的控制下时，在过表达So KAS III的烟草（Nicotiana tabacum，WT-SR）叶中以及在过表达由油菜籽蛋白驱动的Ch KAS III中的任一种的拟南芥和油菜籽（Brassica napus）种子中观察到16：0水平的增加。这些数据表明，这种酶在脂肪酸生物合成中具有普遍的作用，无论其来源于何种植物物种或其表达的组织如何。与野生型相比，转基因油菜籽的含油量也较低。此外，转基因油菜种子中的脂质合成速率明显低于野生型种子。酰基-ACP中间体水平的测量结果以及其他脂肪酸合酶水平的任何变化表明，所有3-酮脂酰-ACP合酶利用的碳供体丙二酸-ACP在转基因植物中是有限制的。这进一步表明丙二酰辅酶A是影响最终油含量以及16：0的进一步扩展的潜在限制因素。
A cDNA coding for 3-ketoacyl-acyl-carrier protein (ACP) synthase III (KAS III) from spinach (Spinacia oleracea; So KAS III) was used to isolate two closely related KAS III clones (Ch KAS III-1 and Ch KAS III-2) from Cuphea hookeriana. Both Ch KAS IIIs are expressed constitutively in all tissues examined. An increase in the levels of 16:0 was observed in tobacco (Nicotiana tabacum, WT-SR) leaves overexpressing So KAS III when under the control of the cauliflower mosaic virus-35S promoter and in Arabidopsis and rapeseed (Brassica napus) seeds overexpressing either of the Ch KAS Ills driven by napin. These data indicate that this enzyme has a universal role in fatty acid biosynthesis, irrespective of the plant species from which it is derived or the tissue in which it is expressed. The transgenic rapeseed seeds also contained lower levels of oil as compared with the wild-type levels. In addition, the rate of lipid synthesis in transgenic rapeseed seeds was notably slower than that of the wild-type seeds. The results of the measurements of the levels of the acyl-ACP intermediates as well as any changes in levels of other fatty acid synthase enzymes suggest that malonyl-ACP, the carbon donor utilized by all the 3- ketoacyl-ACP synthases, is Limiting in the transgenic plants. This further suggests that malonyl-coenzyme A is a potential limiting factor impacting the final oil content as well as further extension of 16:0.