Functions of PKS Genes in Lipid Synthesis of Schizochytrium sp by Gene Disruption and Metabolomics Analysis
Functions of PKS Genes in Lipid Synthesis of Schizochytrium sp by Gene Disruption and Metabolomics Analysis
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基因破坏及代谢组学分析PKS基因在裂殖壶菌脂质合成中的功能
DOI：
10.1007/s10126-018-9849-x
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发表时间：
2018-12-01
影响因子：
3
通讯作者：
He, Ning
中科院分区：
文献类型：
--
作者：
Li, Zhipeng;Chen, Xi;He, Ning
裂殖壶菌（Schizochytrium sp.）是一种海洋微藻，具有很大的潜力，是一种可持续的多不饱和脂肪酸（PUFAs）来源。为研究裂殖壶菌（Schizochytrium sp.）合成多不饱和脂肪酸（PUFA）的主要途径之一是类聚酮脂肪酸合成酶（PKS synthase），从裂殖壶菌（Schizochytrium sp.）PKS基因簇中克隆了链长因子（CLF）和脱氢酶（DH）基因，然后通过同源重组被破坏。结果表明，DH和CLF破坏菌株的PUFA产量显著下降（65.85%和84.24%），而脂肪中饱和脂肪酸（SFA）的比例略有增加。同时，CLF的破坏使C-22 PUFA的比例降低了57.51%，但不影响C-20 PUFA的积累，而DH破坏的突变体则降低了各种PUFA的产生。结合蛋白质预测分析，表明CLF基因在PUFA合成过程中对碳链的延伸，尤其是碳链从C-20延伸到C-22 PUFA的过程中发挥了巨大的作用。代谢组学分析还表明，这两个基因的破坏导致PUFAs的减少，但增加SFA，从而削弱糖酵解和三羧酸（TCA）循环途径。本研究为探讨裂殖壶菌多不饱和脂肪酸的合成机制提供了新的视角。
Schizochytrium sp. is a kind of marine microalgae with great potential as promising sustainable source of polyunsaturated fatty acids (PUFAs). Polyketide synthase-like (PKS synthase) is supposed to be one of the main ways to synthesize PUFAs in Schizochytrium sp. In order to study the exact relationship between PKS and PUFA biosynthesis, chain length factor (CLF) and dehydrogenase (DH) were cloned from the PKS gene cluster in Schizochytrium sp., then disrupted by homologous recombination. The results showed that DH- and CLF-disrupted strains had significant decreases (65.85 and 84.24%) in PUFA yield, while the saturated fatty acid (SFA) proportion in lipids was slightly increased. Meanwhile, the disruption of CLF decreased the C-22 PUFA proportion by 57.51% without effect on C-20 PUFA accumulation while DH-disrupted mutant decreased the production of each PUFA. Combined with analysis of protein prediction, it indicated that CLF gene exerted an enormous function on the carbon chain elongation in PUFA synthesis, especially for the final elongation from C-20 toC-22 PUFAs. Metabolomics analysis also suggested that the disruption of both genes resulted in the decrease of PUFAs but increase of SFAs, thus weakening glycolysis and tricarboxylic acid (TCA) cycle pathways. This study offers a broad new vision to research the mechanism of PUFA synthesis in Schizochytrium sp.