Identification of bifunctional Δ12/ω3 fatty acid desaturases for improving the ratio of ω3 to ω6 fatty acids in microbes and plants
Identification of bifunctional Δ12/ω3 fatty acid desaturases for improving the ratio of ω3 to ω6 fatty acids in microbes and plants
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DOI：
10.1073/pnas.0511079103
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发表时间：
2006-06-20
影响因子：
11.1
通讯作者：
Yadav, Narendra S.
中科院分区：
文献类型：
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作者：
Damude, Howard G.;Zhang, Hongxiang;Yadav, Narendra S.
我们报告了鉴定来自串珠镰刀菌、禾谷镰刀菌和稻瘟病菌的双功能Δ 12/ω 3去饱和酶。这些去饱和酶的双功能活性将它们与所有已知的Δ 12或ω 3脂肪酸去饱和酶区分开来。这些酶的ω 3去饱和酶活性还通过它们将亚油酸（LA）、γ-亚麻酸、二-高-γ-亚麻酸和花生四烯酸分别转化为ω 3脂肪酸、α-亚麻酸（ALA）、十八碳四烯酸、二十碳四烯酸和二十碳五烯酸（EPA）的能力显示出广泛的ω 6脂肪酸底物特异性。系统发育分析表明，ω 3去饱和酶由来自Delta 12去饱和酶祖先的独立基因复制事件产生。表达F.串珠状δ 12/ω 3去饱和酶导致解脂耶氏酵母（一种天然缺乏ω 3去饱和的产油酵母）和大豆中的高ALA含量。在大豆中，种子特异性表达导致转化种子中总脂肪酸（%TFA）ALA的70.9重量%，相比之下，无效分离种子中的10.9%TFA和当前ALA的最佳来源亚麻籽油中的53.2%TFA。转化种子中的ALA/LA比为22.3，分别比无效分离子种子和亚麻籽油提高了110倍和7倍。因此，这些去饱和酶具有生产营养上所需的ω 3长链多不饱和脂肪酸如EPA的潜力，并且在油料种子和产油微生物中ω 3/ω 6长链多不饱和脂肪酸的比率显著提高。
We report the identification of bifunctional Delta 12/omega 3 desaturases from Fusarium moniliforme, Fusarium graminearum, and Magnaporthe grisea. The bifunctional activity of these desaturases distinguishes them from all known Delta 12 or omega 3 fatty acid desaturases. The omega 3 desaturase activity of these enzymes also shows a broad omega 6 fatty acid substrate specificity by their ability to convert linoleic acid (LA), gamma-linolenic acid, di-homo-gamma-linolenic acid, and arachidonic acid to the omega 3 fatty acids, alpha-linolenic acid (ALA), stearidonic acid, eicosatetraenoic acid, and eicosapentaenoic acid (EPA), respectively. Phylogenetic analysis suggests that omega 3 desaturases arose by independent gene duplication events from a Delta 12 desaturases ancestor. Expression of F. moniliforme Delta 12/omega 3 desaturase resulted in high ALA content in both Yarrowia lipolytica, an oleaginous yeast naturally deficient in omega 3 desaturation, and soybean. In soybean, seed-specific expression resulted in 70.9 weight percent of total fatty acid (%TFA) ALA in a transformed seed compared with 10.9%TFA in a null segregant seed and 53.2%TFA in the current best source of ALA, linseed oil. The ALA/LA ratio in transformed seed was 22.3, a 110- and 7-fold improvement over the null segregant seed and linseed oil, respectively. Thus, these desaturases have potential for producing nutritionally desirable omega 3 long-chain polyunsaturated fatty acids, such as EPA, with a significantly improved ratio of omega 3/omega 6 long-chain polyunsaturated fatty acids in both oilseeds and oleaginous microbes.