Metabolic engineering of ω3-very long chain polyunsaturated fatty acid production by an exclusively acyl-CoA-dependent pathway
Metabolic engineering of ω3-very long chain polyunsaturated fatty acid production by an exclusively acyl-CoA-dependent pathway
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DOI：
10.1074/jbc.m802377200
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发表时间：
2008-08-15
影响因子：
4.8
通讯作者：
Feussner, Ivo
中科院分区：
文献类型：
--
作者：
Hoffmann, Mareike;Wagner, Martin;Feussner, Ivo
- 3-超长链多不饱和脂肪酸（VLCPUFA）对人类发育和大脑功能至关重要，因此是人类饮食中不可缺少的组成部分。目前VLCPUFAs的主要来源是海洋鱼类种群，它们的数量正在严重下降，迫切需要开发替代的、可持续的VLCPUFAs来源。我们的研究旨在利用油菜籽等油料作物大规模培养的强大基础设施，在转基因植物中产生二十碳五烯酸等VLCPUFAs。VLCPUFA的生物合成需要长链脂肪酸底物的反复去饱和和反复延伸。在先前的实验中，转基因植物中二十碳五烯酸的产生被一个意想不到的瓶颈所限制，这个瓶颈是由去饱和位点内质网相关磷脂和延伸位点细胞质酰基辅酶a池之间的酰基交换所代表的。在这里，我们报道了建立一个协调的，完全依赖酰基辅酶a的途径，避免了在VLCPUFA生物合成过程中酰基脂质和酰基辅酶a池之间的限速酯交换步骤。该途径由以前未表征的酶定义，由从微藻Mantoniella squamata中分离的cdna编码。概念酶途径首先在酵母中建立和表征，为其可行性提供概念验证数据，随后在拟南芥种子中建立和表征。将酰基辅酶a依赖途径与已知的VLCPUFA生物合成脂联途径进行比较发现，酰基辅酶a依赖途径绕过了拟南芥种子中脂质和酰基辅酶a之间转换δ 6-不饱和脂肪酸的瓶颈。
omega 3-Very long chain polyunsaturated fatty acids (VLCPUFA) are essential for human development and brain function and, thus, are indispensable components of the human diet. The current main source of VLCPUFAs is represented by ocean fish stocks, which are in severe decline, and the development of alternative, sustainable sources of VLCPUFAs is urgently required. Our research aims at exploiting the powerful infrastructure available for the large scale culture of oilseed crops, such as rapeseed, to produce VLCPUFAs such as eicosapentaenoic acid in transgenic plants. VLCPUFA biosynthesis requires repeated desaturation and repeated elongation of long chain fatty acid substrates. In previous experiments the production of eicosapentaenoic acid in transgenic plants was found to be limited by an unexpected bottleneck represented by the acyl exchange between the site of desaturation, endoplasmic reticulum-associated phospholipids, and the site of elongation, the cytosolic acyl-CoA pool. Here we report on the establishment of a coordinated, exclusively acyl-CoA-dependent pathway, which avoids the rate-limiting transesterification steps between the acyl lipids and the acyl-CoA pool during VLCPUFA biosynthesis. The pathway is defined by previously uncharacterized enzymes, encoded by cDNAs isolated from the microalga Mantoniella squamata. The conceptual enzymatic pathway was established and characterized first in yeast to provide proof-of-concept data for its feasibility and subsequently in seeds of Arabidopsis thaliana. The comparison of the acyl-CoA-dependent pathway with the known lipid-linked pathway for VLCPUFA biosynthesis showed that the acyl-CoA-dependent pathway circumvents the bottleneck of switching the Delta 6-desaturated fatty acids between lipids and acyl-CoA in Arabidopsis seeds.