Novel insights into type 2 diacylglycerol acyltransferases in microalgaMyrmecia incisa
Novel insights into type 2 diacylglycerol acyltransferases in microalgaMyrmecia incisa
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对微藻 Myrmecia incisa 中 2 型二酰基甘油酰基转移酶的新见解
DOI：
10.1007/s10811-020-02071-x
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发表时间：
2021
影响因子：
3.3
通讯作者：
Zhou Zhi-Gang
中科院分区：
文献类型：
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作者：
Liu Wei;Sun Zheng;Chen Chun-Xiu;Liu Jian-Guo;Zhou Zhi-Gang
桃金娘科绿色藻富含花生四烯酸（ArA），主要以三酰甘油（TAG）的形式存在于脂滴中。在TAG的从头生物合成中，二酰基甘油酰基转移酶（DGAT）作为限速酶催化最后的和关键的步骤。在此之前，我们的实验室已经报道了M中的第一个DGAT。本研究进一步鉴定了一个新的DGAT。通过对转录组数据库的同源性搜索和注释，获得了一个新的DGAT 2的重叠群，并通过RACE克隆了其全长cDNA，命名为MiDGAT 2C。对于这种新的MiDGAT2C，生物信息学分析显示存在多个保守的氨基酸残基和序列。利用TAG缺陷型酵母系统，通过互补试验确定其合成TAG的功能。此外，将MiDGAT2C与其他MiDGAT就其底物偏好进行比较。脂肪酸喂养和体外酶测定的结果表明不同的底物特异性之间的MiDGAT成员。虽然MiDGAT2C对ArA没有活性，但MiDGAT2A对ArA掺入TAG的贡献最大。本研究的发现扩展了我们对DGAT分子基础的认识，为M的研究提供了更多的线索。切皮是一种很有前途的富含ArA的TAG的原料。
The green algaMyrmecia incisais rich in arachidonic acid (ArA), which mainly stores in lipid droplets in the form of triacylglycerol (TAG). In the de novo biosynthesis of TAG, diacylglycerol acyltransferase (DGAT) catalyzes the final and committed step as a rate-limiting enzyme. Previously, our lab has reported the first DGAT inM. incisa, and in this study, a new DGAT was further identified. Through homology search against our transcriptome database and annotation, a new contig corresponding to the putative DGAT2 was targeted, whose full-length cDNA was cloned by RACE and designated asMiDGAT2C. For this new MiDGAT2C, bioinformatics analyses revealed the presence of multiple conserved amino acid residues and sequences. Its function to synthesize TAG was determined by complementation assay using the TAG-deficient yeast system. Besides, MiDGAT2C was compared with other MiDGATs with respect to their substrate preference. Results of fatty acid feeding and in vitro enzymatic assays indicated diverse substrate specificities among MiDGAT members. While MiDGAT2C showed no activity on ArA, MiDGAT2A made the most contribution to incorporate ArA into TAG. Findings of this study expand our knowledge on the molecular basis of DGAT, shedding more light onM. incisaas a promising feedstock for ArA-rich TAG.