The PAH1-encoded phosphatidate phosphatase (PAP) catalyzes the Mg2+ -dependent dephosphorylation of phosphatidate to produce diacylglycerol, which can be acylated to form triacylglycerol (TAG). In the model oleaginous yeast Yarrowia lipolytica, TAG is the major lipid produced, and its biosynthesis requires a continuous supply of diacylglycerol, which can be provided by the PAP reaction. However, the regulation of Pah1 has not been studied in detail in Y. lipolytica, and thus its contribution to the biosynthesis of TAG in this yeast is not well understood. In this work, we examined the regulation of the PAH1-mediated PAP activity and Pah1 abundance and localization in cells growing on glucose. We found that Pah1 abundance and localization were regulated in a growth-dependent manner, yet the loss of Pah1 did not have a major effect on PAP activity. We also examined the effects of the Y. lipolytica pah1Δ mutation on cell physiology and lipid biosynthesis. The lack of Pah1 in the pah1Δ mutant resulted in a moderate decrease in TAG levels and an increase in phospholipid levels. These results showed that Pah1 contributed to TAG biosynthesis in Y. lipolytica but also suggested the presence of other activities in the pah1Δ mutant that compensate for the loss of Pah1. Also, the levels of linoleic acid were elevated in pah1Δ cells with a concomitant decrease in the oleic acid levels suggesting that the pah1Δ mutation affected the biosynthesis of fatty acids.

中文翻译：

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解脂耶氏酵母PAH1同系物有助于但在葡萄糖生长期间三酰基甘油生物合成中不是必需的。

PAH1编码的磷脂酰磷酸酶（PAP）催化磷酸酯的Mg2 +依赖性去磷酸化生成二酰基甘油，可将其酰化形成三酰基甘油（TAG）。在模型油质酵母解脂耶氏酵母中，TAG是产生的主要脂质，其生物合成需要连续供应二酰基甘油，这可以通过PAP反应来提供。但是，尚未在解脂耶氏酵母中详细研究Pah1的调控，因此，尚不清楚它对这种酵母中TAG生物合成的贡献。在这项工作中，我们检查了PAH1介导的PAP活性以及Pah1丰度和葡萄糖生长细胞中的定位的调节。我们发现Pah1的丰度和本地化以增长依赖的方式进行调节，但Pah1的丢失对PAP活性没有重大影响。我们还检查了解脂耶氏酵母pah1Δ突变对细胞生理和脂质生物合成的影响。pah1Δ突变体中Pah1的缺乏导致TAG水平适度降低，磷脂水平升高。这些结果表明，Pah1有助于解脂耶氏酵母中TAG的生物合成，但也暗示了在pah1Δ突变体中存在其他活动，这些活动可以补偿Pah1的丢失。另外，pah1Δ细胞中亚油酸水平升高，同时油酸水平下降，这表明pah1Δ突变影响脂肪酸的生物合成。这些结果表明，Pah1有助于解脂耶氏酵母中TAG的生物合成，但也暗示了在pah1Δ突变体中存在其他活动，这些活动可以补偿Pah1的丢失。另外，pah1Δ细胞中亚油酸水平升高，同时油酸水平下降，这表明pah1Δ突变影响脂肪酸的生物合成。这些结果表明，Pah1有助于解脂耶氏酵母中TAG的生物合成，但也暗示了在pah1Δ突变体中存在其他活动，这些活动可以补偿Pah1的丢失。另外，pah1Δ细胞中亚油酸水平升高，同时油酸水平下降，这表明pah1Δ突变影响脂肪酸的生物合成。