Table_1_Functional Characterization of the Monogalactosyldiacylglycerol Synthase Gene ptMGD2 in the Diatom Phaeodactylum tricornutum.xlsx

Monogalactosyldiacylglycerol (MGDG) is the most abundant polar lipid in thylakoid membrane, wherein it plays critical roles related to thylakoid membrane assembly and function in diatoms. However, diatom MGDG biosynthesis has not been fully characterized. In this study, we investigated the role of a novel MGDG synthase (ptMGD2), which is one of the key enzymes for MGDG biosynthesis, in the model diatom Phaeodactylum tricornutum. An analysis of subcellular localization demonstrated that the ptMGD2 is mainly localized in plastids. Gene disruption by gene editing of ptMGD2 resulted in delayed growth, decrease in oxygen evolution rate, reduced MGDG and digalactosyldiacylglycerol (using MGDG as the substrate) content as well as lipid remodeling. Considered together, these observations provide novel insights into the importance of ptMGD2 for regulating MGDG biosynthesis and its potential roles in biotechnical application of Phaeodactylum.

单半乳糖基二酰甘油（Monogalactosyldiacylglycerol, MGDG）是类囊体膜中含量最为丰富的极性脂质，在硅藻的类囊体膜组装与功能行使过程中发挥关键作用。然而，目前硅藻MGDG的生物合成途径尚未得到充分解析。本研究以模式硅藻三角褐指藻（Phaeodactylum tricornutum）为研究对象，探究了新型MGDG合酶ptMGD2的功能——该酶是MGDG生物合成的关键酶之一。亚细胞定位分析结果显示，ptMGD2主要定位于质体中。通过基因编辑对ptMGD2进行基因敲除后，菌株出现生长延迟、放氧速率下降、MGDG及以MGDG为底物合成的双半乳糖基二酰甘油（digalactosyldiacylglycerol）含量降低，同时伴随脂质重塑现象。综合上述实验结果，本研究为阐明ptMGD2在调控MGDG生物合成中的重要性，以及其在三角褐指藻生物技术应用中的潜在功能提供了全新的认知。