球等鞭金藻中Δ5去饱和酶基因的克隆与功能鉴定  

ISOLATION AND FUNCTIONAL ANALYSIS OF A Δ5 DESATURASE GENE FROM ISOCHRYSIS GALBANA

作　　者：孙全喜[1] 李雪滢[1] 郑德松[1] 刘江[1] 李新征[1] 亓宝秀[1] 

机构地区：[1]山东农业大学作物生物学国家重点实验室,泰安271018

出　　处：《水生生物学报》2012年第3期412-419,共8页Acta Hydrobiologica Sinica

基　　金：国家自然科学基金(30970222);长江学者和创新团队发展计划(IRT0635);农业部2009ZX08005-024B;山东省科技攻关项目(2007GGB02001)资助

摘　　要：球等鞭金藻(Isochrysis galbana)是一类单细胞海洋微藻,富含二十二碳六烯酸(DHA,22:6Δ4,7,10,13,16,19)。我们利用RACE的方法从球等鞭金藻cDNA文库中同源克隆到一个大小为1329 bp的cDNA片段,编码442个氨基酸的多肽,分子量约49.9 kD。生物信息学分析表明,其编码产物N端具有细胞色素b5结构域,以及与电子传递有关的三个富含组氨酸的结构域,与Pavlova salinaΔ5去饱和酶同源性最高,达56%,故将该基因命名为IgD5。酿酒酵母功能鉴定实验表明,其编码的蛋白质具有Δ5去饱和酶活性,能够将二高-γ-亚麻酸(DGLA,20:3Δ8,11,14)转化成花生四烯酸(AA,20:4Δ5,8,11,14),转化效率平均为34.6%,最高可达40.3%。The very long chain （〉~C20） polyunsaturated fatty acids （VLCPUFA）, such as arachidonic acid （AA; 20：4036）, eicosapentaenoic acid （EPA; 20：5033） and docosapentaenoic acid （DHA; 22：6033） are essential for human health and nutrition. Dietary supplementation with these fatty acids is not only helpful for fetal neuronal, but also can reduce the risk of cardiovascular disease, hypertension, inflammatory and other diseases. Human beings can synthesize these fatty acids from the two essential fatty acid, linoleic acid （LA; 18：2036） and ct-linolenic acid （ALA; 18：3033）, which must be obtained from the diet. However, the synthetic efficiency is somewhat limited, and can not meet our daily requirement. AA can be obtained easily from meat, egg and milk, often in excessive amounts, EPA and DHA, however, can only be obtained from marine fish that are so often omitted from the modern diet, in much lower amounts than required. This shortage is further worsened by the fact that the natural marine fish resources have been depleting fast in recent years. In addition, the recent findings of toxic chemicals in fish oil has created fears for the consumption of fish products hence reduced the intake of EPA and DHA even further. Therefore, alternative source of these VLCPUFAs are therefore de- sirable. To obtain them from oil plants in commercial and sustainable quantities is particularly attractive. However, no oil-seed species produce such products naturally. The VLCPUFA biosynthesis pathways in organisms such as filamen- tous fungus and marine microalgae have been elaborated. Accordingly, genes encoding for elongases and desaturases involved in their metabolic pathway have been cloned from a variety of organisms including algae, mosses, fungi, nematodes and humans in the last 10 years. The reconstruction of the VLCPUFAs metabolic pathway into higher plants has been achieved in Arabidopsis, linseed, mustard and soya bean by introducing a set of 3--9 fatty acid desaturase and elongase genes. Howe

关 键 词：球等鞭金藻 Δ5去饱和酶 超长链多不饱和脂肪酸 

分 类 号：Q781[生物学—分子生物学]