Heterologous expression of a fatty acid hydroxylase gene in developing seeds of Arabidopsis thaliana
Heterologous expression of a fatty acid hydroxylase gene in developing seeds of Arabidopsis thaliana
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DOI：
10.1007/s00425-003-1015-6
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发表时间：
2003-07-01
期刊：
影响因子：
4.3
通讯作者：
Kunst, L
中科院分区：
文献类型：
--
作者：
Smith, MA;Moon, H;Kunst, L
蓖麻油酸delta12 -羟化酶cDNA在拟南芥种子发育中的表达Heynh。结果合成了四种新型羟基脂肪酸。这些化合物先前已被鉴定为蓖麻油酸（12-羟基十八烷基顺-9-烯酸：18:1-OH）、密辛酸（12-羟基十八烷基顺-9,15-烯酸：18:2-OH）、去槲皮酸（14-羟基二十烷基顺-11-烯酸：20:1-OH）和金耳酸（14-羟基二十烷基顺-11,17-烯酸：20:2-OH）。利用缺乏FAE1浓缩酶或FAD3 ER δ -15去饱和酶活性的拟南芥突变系，我们已经证明这些酶分别是合成C20羟基脂肪酸和多不饱和羟基脂肪酸所必需的。对转化植物种子脂肪酸组成的分析表明，与种子中羟基脂肪酸含量相关的油酸（18:1）含量急剧增加，亚油酸（18:2）含量急剧下降。缺乏FAD2 （ER delta12 -去饱和酶）活性的植株，其18:1含量降低，与羟基脂肪酸含量对应的18:2含量略有升高。蓖麻羟化酶蛋白在酵母中的表达表明该酶具有低水平的脂肪酸delta12 -去饱和酶活性。脂肪酶催化转化植物中甘油三酯的1,3特异性脂解表明，蓖麻油酸不排除在甘油三酯的sn-2位置，但它是唯一存在于该位置的羟基脂肪酸。
Expression of a cDNA encoding the castor bean (Ricinus communis L.) oleate Delta12-hydroxylase in the developing seeds of Arabidopsis thaliana (L.) Heynh. results in the synthesis of four novel hydroxy fatty acids. These have been previously identified as ricinoleic acid (12-hydroxy-octadec-cis-9-enoic acid: 18:1-OH), densipolic acid (12-hydroxy-octadec-cis-9,15-enoic acid: 18:2-OH), lesquerolic acid (14-hydroxy-eicos-cis-11-enoic acid: 20:1-OH) and auricolic acid (14-hydroxy-eicos-cis-11,17-enoic acid: 20:2-OH). Using mutant lines of Arabidopsis that lack the activity of the FAE1 condensing enzyme or FAD3 ER Delta-15-desaturase, we have shown that these enzymes are required for the synthesis of C20 hydroxy fatty acids and polyunsaturated hydroxy fatty acids, respectively. Analysis of the seed fatty acid composition of transformed plants demonstrated a dramatic increase in oleic acid (18:1) levels and a decrease in linoleic acid (18:2) content correlating to the levels of hydroxy fatty acid present in the seed. Plants in which FAD2 (ER Delta12-desaturase) activity was absent showed a decrease in 18:1 content and a slight increase in 18:2 levels corresponding to hydroxy fatty acid content. Expression of the castor hydroxylase protein in yeast indicates that this enzyme has a low level of fatty acid Delta12-desaturase activity. Lipase catalysed 1,3-specific lipolysis of triacylglycerol from transformed plants demonstrated that ricinoleic acid is not excluded from the sn-2 position of triacylglycerol, but is the only hydroxy fatty acid present at this position.