Identification of the wax ester synthase/acyl-coenzyme A: Diacylglycerol acyltransferase WSD1 required for stem wax ester biosynthesis in Arabidopsis
Identification of the wax ester synthase/acyl-coenzyme A: Diacylglycerol acyltransferase WSD1 required for stem wax ester biosynthesis in Arabidopsis
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DOI：
10.1104/pp.108.123471
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发表时间：
2008-09-01
期刊：
影响因子：
7.4
通讯作者：
Kunst, Ljerka
中科院分区：
文献类型：
--
作者：
Li, Fengling;Wu, Xuemin;Kunst, Ljerka
蜡酯是由脂肪醇和酸组成的中性脂类，这两个部分通常都是长链(C-16和C-18)或超长链(C-20或更长)的碳结构。它们在细菌、昆虫、哺乳动物和陆地植物中具有多种生物学功能，也是各种工业应用的重要底物。在植物中，蜡酯主要存在于覆盖在主茎表面的角质层中，但它们也会在少数几种植物的种子油中积累到高浓度，包括霍霍巴(Simmondsia Chinensis)，这是一种沙漠灌木，是这些化合物的主要商业来源。在这里，我们报道了WSD1的鉴定和特性，WSD1是双功能蜡酯合成酶/二酰甘油酰基转移酶基因家族的成员，它在拟南芥茎中蜡酯的合成中起着关键作用，首次被证明是wsd1突变体茎中蜡酯水平的显著降低。用表达WSD1的大肠杆菌蛋白提取物进行体外分析表明，该酶具有高水平的蜡合酶活性和大约10倍低的二酰甘油酰基转移酶活性。WSD1基因在酿酒酵母中的表达导致蜡酯的积累，而不是三酰甘油的积累，这表明WSD1主要作为蜡合酶发挥作用。对WSD1表达的分析表明，该基因在花、茎的顶部和叶片中转录。全功能黄色荧光蛋白标记的WSD1蛋白定位于内质网，表明酒精形成途径的最终产物蜡酯的生物合成发生在这个亚细胞室。
Wax esters are neutral lipids composed of aliphatic alcohols and acids, with both moieties usually long-chain (C-16 and C-18) or very-long-chain (C-20 and longer) carbon structures. They have diverse biological functions in bacteria, insects, mammals, and terrestrial plants and are also important substrates for a variety of industrial applications. In plants, wax esters are mostly found in the cuticles coating the primary shoot surfaces, but they also accumulate to high concentrations in the seed oils of a few plant species, including jojoba (Simmondsia chinensis), a desert shrub that is the major commercial source of these compounds. Here, we report the identification and characterization of WSD1, a member of the bifunctional wax ester synthase/diacylglycerol acyltransferase gene family, which plays a key role in wax ester synthesis in Arabidopsis (Arabidopsis thaliana) stems, as first evidenced by severely reduced wax ester levels of in the stem wax of wsd1 mutants. In vitro assays using protein extracts from Escherichia coli expressing WSD1 showed that this enzyme has a high level of wax synthase activity and approximately 10-fold lower level of diacylglycerol acyltransferase activity. Expression of the WSD1 gene in Saccharomyces cerevisiae resulted in the accumulation of wax esters, but not triacylglycerol, indicating that WSD1 predominantly functions as a wax synthase. Analyses of WSD1 expression revealed that this gene is transcribed in flowers, top parts of stems, and leaves. Fully functional yellow fluorescent protein-tagged WSD1 protein was localized to the endoplasmic reticulum, demonstrating that biosynthesis of wax esters, the final products of the alcohol-forming pathway, occurs in this subcellular compartment.