Novel fatty acid elongases and their use for the reconstitution of docosahexaenoic acid biosynthesis
Novel fatty acid elongases and their use for the reconstitution of docosahexaenoic acid biosynthesis
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DOI：
10.1194/jlr.m400181-jlr200
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发表时间：
2004-10-01
影响因子：
6.5
通讯作者：
Heinz, E
中科院分区：
文献类型：
--
作者：
Meyer, A;Kirsch, H;Heinz, E
在藻类中，二十二碳六烯酸（22：6 ω 3; DHA）的生物合成通过二十碳五烯酸（20：5 ω 3; EPA）延伸至22：5 ω 3进行，这是最终Δ 4去饱和所需的底物。为了分离特异于该步骤的延伸酶，我们使用来自苔藓小立碗藓的延伸酶序列PpPSE 1作为查询，从藻类Ostreococcus tauri和Thalassiosira pastana、从鱼Oncorhynchus mykiss、从蛙Xenopus laevis和从海鞘Ciona pasta中搜索表达的序列标签和基因组数据库。在酵母中表达所鉴定的延伸酶候选物的开放阅读框用于功能表征。由此，我们从O. tauri和T. Escherichana：一种特异于（Delta 6-）C18-PUFA的延伸，一种特异于（Delta 5-）C20-PUFA，显示出对EPA的最高活性。从O. mykiss，X. laevis和C. C18-和C20-PUFA均被接受。通过共表达T. Chaanana和O. tauri分别与来自另外两种藻类的Δ 5-和Δ 4-去饱和酶一起，我们成功地在十八碳四烯酸饲喂的酵母中实现了DHA合成。这可能被认为是在未来努力将该生物合成序列实施到转基因油料作物中的令人鼓舞的第一步。
In algae, the biosynthesis of docosahexaenoic acid (22:6omega3; DHA) proceeds via the elongation of eicosapentaenoic acid (20:5omega3; EPA) to 22:5omega3, which is required as a substrate for the final Delta4 desaturation. To isolate the elongase specific for this step, we searched expressed sequence tag and genomic databases from the algae Ostreococcus tauri and Thalassiosira pseudonana, from the fish Oncorhynchus mykiss, from the frog Xenopus laevis, and from the sea squirt Ciona intestinalis using as a query the elongase sequence PpPSE1 from the moss Physcomitrella patens. The open reading frames of the identified elongase candidates were expressed in yeast for functional characterization. By this, we identified two types of elongases from O. tauri and T. pseudonana: one specific for the elongation of (Delta6-)C18-PUFAs and one specific for (Delta5-)C20-PUFAs, showing highest activity with EPA. The clones isolated from O. mykiss, X. laevis, and C. intestinalis accepted both C18- and C20-PUFAs. By coexpression of the Delta6- and Delta5-elongases from T. pseudonana and O. tauri, respectively, with the Delta5- and Delta4-desaturases from two other algae we successfully implemented DHA synthesis in stearidonic acid-fed yeast. This may be considered an encouraging first step in future efforts to implement this biosynthetic sequence into transgenic oilseed crops.