Department of Agricultural Biotechnology, National Academy of Agricultural Science, RDA, Suwon 441-707, Republic of Korea.
Gene. 2013 Dec 1;531(2):253-62. doi: 10.1016/j.gene.2013.08.095. Epub 2013 Sep 9.
Fatty acid desaturase 2 (FAD2), which resides in the endoplasmic reticulum (ER), plays a crucial role in producing linoleic acid (18:2) through catalyzing the desaturation of oleic acid (18:1) by double bond formation at the delta 12 position. FAD2 catalyzes the first step needed for the production of polyunsaturated fatty acids found in the glycerolipids of cell membranes and the triacylglycerols in seeds. In this study, four FAD2 genes from amphidiploid Brassica napus genome were isolated by PCR amplification, with their enzymatic functions predicted by sequence analysis of the cDNAs. Fatty acid analysis of budding yeast transformed with each of the FAD2 genes showed that whereas BnFAD2-1, BnFAD2-2, and BnFAD2-4 are functional enzymes, and BnFAD2-3 is nonfunctional. The four FAD2 genes of B. napus originated from synthetic hybridization of its diploid progenitors Brassica rapa and Brassica oleracea, each of which has two FAD2 genes identical to those of B. napus. The BnFAD2-3 gene of B. napus, a nonfunctional pseudogene mutated by multiple nucleotide deletions and insertions, was inherited from B. rapa. All BnFAD2 isozymes except BnFAD2-3 localized to the ER. Nonfunctional BnFAD2-3 localized to the nucleus and chloroplasts. Four BnFAD2 genes can be classified on the basis of their expression patterns.
脂肪酸去饱和酶 2（FAD2）位于内质网（ER）中，通过在 delta 12 位形成双键催化油酸（18:1）的去饱和作用，在产生亚油酸（18:2）方面发挥着关键作用。FAD2 催化细胞膜甘油磷脂和种子三酰基甘油中发现的多不饱和脂肪酸生产所需的第一步。在这项研究中，通过 PCR 扩增从双二倍体甘蓝型油菜基因组中分离出了四个 FAD2 基因，并通过 cDNA 的序列分析预测了它们的酶功能。将每个 FAD2 基因转化为芽殖酵母的脂肪酸分析表明，BnFAD2-1、BnFAD2-2 和 BnFAD2-4 是功能性酶，而 BnFAD2-3 是非功能性的。油菜的四个 FAD2 基因来源于其二倍体亲本芸薹和甘蓝的合成杂交，每个亲本都有两个与油菜相同的 FAD2 基因。油菜的 BnFAD2-3 基因是一个无功能的假基因，由于多个核苷酸的缺失和插入而发生突变，它是从芸薹遗传而来的。除了 BnFAD2-3 之外，所有的 BnFAD2 同工酶都定位于内质网。无功能的 BnFAD2-3 定位于细胞核和叶绿体。基于表达模式，可以将四个 BnFAD2 基因进行分类。
