Aki T, Shimada Y, Inagaki K, Higashimoto H, Kawamoto S, Shigeta S, Ono K, Suzuki O
Department of Molecular Biotechnology, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan.
Biochem Biophys Res Commun. 1999 Feb 24;255(3):575-9. doi: 10.1006/bbrc.1999.0235.
Mammalian cDNA fragments putatively encoding amino acid sequences characteristic of the fatty acid desaturase were obtained using expressed sequence tag (EST) sequence informations. These fragments were subsequently used to screen a rat liver cDNA library, yielding a 1573-bp clone. Expression of DNA fragment containing either of two possible open reading frames (nucleotide numbers 97-1431 and 148-1431) of the isolated clone in yeast led to the accumulation of gamma-linolenic acid in the presence of exogenous linoleic acid. In this system, the addition of alpha-linolenic acid also resulted in the accumulation of its Delta-6 desaturated product whereas dihomo-gamma-linolenic acid failed to be a substrate. These results indicate that the protein encoded by the rat cDNA is Delta-6 fatty acid desaturase, and the first 17 amino acids corresponding to the coding region 97-147 of the clone are not required to function in yeast.
利用表达序列标签（EST）序列信息获得了推测编码脂肪酸去饱和酶特征性氨基酸序列的哺乳动物cDNA片段。随后用这些片段筛选大鼠肝脏cDNA文库，得到一个1573 bp的克隆。在酵母中表达含有分离克隆两个可能开放阅读框（核苷酸编号97 - 1431和148 - 1431）之一的DNA片段，在外源亚油酸存在的情况下导致γ-亚麻酸的积累。在这个系统中，添加α-亚麻酸也导致其Δ-6去饱和产物的积累，而二高-γ-亚麻酸不能作为底物。这些结果表明，大鼠cDNA编码的蛋白质是Δ-6脂肪酸去饱和酶，并且与克隆的编码区97 - 147对应的前17个氨基酸在酵母中发挥功能不是必需的。
