Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute,Domaine de Vilvert, Jouy-en-Josas 78350, France.
Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Department of Physiology and Cell Biology, Correnstr. 3, Gatersleben 06466, Germany.
FEMS Yeast Res. 2020 Dec 17;20(8). doi: 10.1093/femsyr/foaa060.
Blastobotrys raffinosifermentans is an ascomycetous yeast with biotechnological applications, recently shown to be an oleaginous yeast accumulating lipids under nitrogen limitation. Diacylglycerol acyltransferases (DGATs) act in the lipid storage pathway, in the last step of triacylglycerol biosynthesis. Two DGAT families are widespread in eukaryotes. We first checked that B. raffinosifermentans strain LS3 possessed both types of DGAT, and we then overexpressed the native DGAT-encoding genes, DGA1 and DGA2, separately or together. DGA2 (from the DGAT1 family) overexpression was sufficient to increase lipid content significantly in LS3, to up to 26.5% of dry cell weight (DCW), 1.6 times the lipid content of the parental strain (16.90% of DCW) in glucose medium under nitrogen limitation. By contrast, DGA1 (of the DGAT2 type) overexpression led to a large increase (up to 140-fold) in the amount of the corresponding transcript, but had no effect on overall lipid content relative to the parental strain. Analysis of the expression of the native genes over time in the parental strain revealed that DGA2 transcript levels quadrupled between 8 and 24 h in the N-limited lipogenic medium, whereas DGA1 transcript levels remained stable. This survey highlights the predominant role of the DGAT1 family in lipid accumulation and demonstrates the suitability of B. raffinosifermentans for engineering for lipid production.
裂殖酵母（Blastobotrys raffinosifermentans）是一种具有生物技术应用的子囊菌酵母，最近被证明是一种在氮限制下积累油脂的油脂酵母。二酰基甘油酰基转移酶（DGATs）在脂质储存途径中发挥作用，是三酰基甘油生物合成的最后一步。两种 DGAT 家族在真核生物中广泛存在。我们首先检查了 LS3 菌株是否具有两种类型的 DGAT，然后分别或一起过表达了天然的 DGAT 编码基因 DGA1 和 DGA2。DGA2（来自 DGAT1 家族）的过表达足以显著增加 LS3 的脂质含量，在氮限制下的葡萄糖培养基中，脂质含量高达干重的 26.5%（比亲本菌株的脂质含量 16.90%增加了 1.6 倍）。相比之下，DGA1（DGAT2 类型）的过表达导致相应转录本的大量增加（高达 140 倍），但相对于亲本菌株，对总脂质含量没有影响。对亲本菌株中原基因随时间表达的分析表明，在氮限制的脂生成培养基中，DGA2 的转录水平在 8 至 24 小时之间增加了四倍，而 DGA1 的转录水平保持稳定。这项研究强调了 DGAT1 家族在脂质积累中的主要作用，并证明了裂殖酵母适合用于脂质生产的工程改造。
