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高山被孢霉内过表达硫酯酶 ACOT8I 对其
脂肪酸代谢的影响
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郭敬,杨波,陈卫,陈永泉,张灏,陈海琴
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(江南大学食品学院,无锡 214122) 5
基金项目:国家自然科学基金(21276108)
作者简介:郭敬(1989-),女,硕士生,食品生物技术
通信联系人:陈海琴(1978-),女,教授、博导,食品生物技术. E-mail: haiqinchen@jiangnan.edu.cn
摘要:硫酯酶作为调控脂肪酸代谢的关键酶,能催化脂酰-ACP/CoA 中羰基基团和硫原子的
水解,即硫酯键的水解,从而终止脂肪酸的合成。为了探究硫酯酶在高山被孢霉脂肪酸代谢
调节过程中的作用,本研究过表达了其内源性硫酯酶 ACOT8I。研究结果显示高山被孢霉重
组菌总脂的含量和组成与野生型菌株保持一致。而重组菌胞内游离脂肪酸的总含量从 0.9% 10
增加到了 2.8%,呈现大约 3 倍的增长。其中游离态总脂肪酸中亚油酸占了 9%,而对照菌株
中仅占 1.3%。在重组菌中亚麻酸和花生四烯酸的含量分别占了游离形态总脂肪酸的 4%和
25%,而野生型的高山被孢霉重组菌检测不到游离形态的亚麻酸和花生四烯酸。这些结果表
明硫酯酶 ACOT8I 的过表达可以增强脂酰-CoA 到游离态脂肪酸的转化,增加重组菌内游离
态脂肪酸的总量,改变游离形式脂肪的组成比例。 15
关键词:食品科学;高山被孢霉;硫酯酶;游离态脂肪酸;过表达
中图分类号:TS201.3
Effect of overexpression of ACOT8I on lipid metabolism in
Mortierella alpina 20
GUO Jing, YANG Bo, CHEN Wei, CHEN Yongquan, ZHANG Hao, CHEN Haiqin
(School of Food Science and Technology, Jiangnan University, Wuxi 214122)
Abstract: Thioesterases (TEs) hydrolyse the thioester bond between a sulphur atom and a carbonyl
group, playing an essential role in the lipid metabolism. To explore the role of TEs in mediating fatty
acids metabolism in Mortierella alpina, the homogeneous acyl-CoA thioesterase ACOT8I was 25
overexpressed. The contents of total fatty acids (TFAs) were the same in the recombinant strains as in
the wild-type strain, whilst the production of free fatty acids (FFAs) was enhanced from about 0.9% to
2.8%. Linoleic acid constituted about 9% of the TFAs in the FFA fraction in the recombinant strain, but
only about 1.3% in the control strain. Arachidonic acid (AA) and gamma-linolenic acid (GLA) and
accounted for about 25% and 4% of the TFAs, respectively, in the FFA fraction in the engineered strain, 30
whilst no GLA or AA was detected in the wild-type strain. Overexpression of the TE ACOT8I in
Mortierella alpina reinforced the flux from acyl-CoAs to FFAs, tailored the FA profiles of the lipid
species and improved the production of FFAs.
Key words: Food science; Mortierella alpina; Thioesterases; Free fatty acids; Overexpression
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0 引言
硫酯酶能够催化羰基基团和硫原子的水解,即硫酯键的水解,是调节脂肪酸合成,脂质
代谢,非核糖体多肽的合成及其他代谢途径的关键酶
[1]
。关于硫酯酶的分类,目前比较受认
可的是以蛋白质一级结构中氨基酸的保守序列为主要参考标准,再辅以三级结构折叠域和折40
叠机制以及催化残基位点的相似度对硫酯酶进行分类的方法
[2]
。硫酯酶被分为 23 个家族,
即从 TE1 到 TE23。这种分类方法几乎涵盖了所有类型的硫酯酶:脂酰-CoA 型 (TE1-13)、
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