Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central, Ibaraki, Japan.
Appl Microbiol Biotechnol. 2010 Aug;87(6):2185-93. doi: 10.1007/s00253-010-2679-z. Epub 2010 May 29.
Since Saccharomyces cerevisiae contains Delta9 fatty acid desaturase (OLE1) as a sole fatty acid desaturase, it produces saturated and monounsaturated fatty acids of 16- and 18-carbon compounds. We showed earlier that Kluyveromyces lactis Delta12 (KlFAD2) and omega3 (KlFAD3) fatty acid desaturase genes enabled S. cerevisiae to make also polyunsaturated fatty acids (PUFAs), linoleic (18:2n-6), and alpha-linolenic (18:3n-3) acids. Unlike Delta9 fatty acid desaturase Ole1p, the two added fatty acid desaturases (KlFAD2and KlFAD3) do not contain a cytochrome b5 domain, and we now report on effects of the overexpression of K. lactis and S. cerevisiae cytochrome b5 (CYB5) genes as well as temperature effects on PUFA synthesis. Without extra cytochrome b5, while PUFA synthesis is significant at low temperature (20 degrees C), it was marginal at 30 degrees C. Overexpression of cytochrome b5 at 20 degrees C did not affect the fatty acid synthesis so much, but it significantly enhanced the synthesis of PUFA at 30 degrees C.
由于酿酒酵母含有Δ9脂肪酸去饱和酶（OLE1）作为唯一的脂肪酸去饱和酶，它产生 16 碳和 18 碳化合物的饱和和单不饱和脂肪酸。我们之前表明，克鲁维酵母的Δ12（KlFAD2）和ω3（KlFAD3）脂肪酸去饱和酶基因使酿酒酵母能够产生多不饱和脂肪酸（PUFAs），亚油酸（18:2n-6）和α-亚麻酸（18:3n-3）。与Δ9脂肪酸去饱和酶 Ole1p不同，这两种添加的脂肪酸去饱和酶（KlFAD2 和 KlFAD3）不含有细胞色素 b5 结构域，我们现在报告了克鲁维酵母和酿酒酵母细胞色素 b5（CYB5）基因的过表达以及温度对 PUFAs 合成的影响。没有额外的细胞色素 b5，虽然在低温（20°C）时 PUFAs 合成显著，但在 30°C 时则微不足道。在 20°C 时过表达细胞色素 b5 并没有对脂肪酸合成产生太大影响，但它在 30°C 时显著增强了 PUFAs 的合成。
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