Phosphatidate phosphatase activity is induced during lipogenesis in the oleaginous yeast Yarrowia lipolytica

Abstract

Phosphatidate (PA) phosphatase dephosphorylates the membrane phospholipid PA to diacylglycerol (DAG) that can be used for the synthesis of the storage lipid triacylglycerol (TAG). In Yarrowia lipolytica, TAG biosynthesis is induced during the lipogenic phase, which results in the accumulation of this lipid in cells. The accumulation of TAG during lipogenesis requires the supply of DAG, but the source of this DAG is not known in Y. lipolytica. In this study, the regulation of PA phosphatase during lipogenesis and its contribution to TAG biosynthesis was examined in Y. lipolytica. Lipogenesis was triggered by growing cells in high-glucose media, whereas control cultures were grown in low-glucose media. PA phosphatase activity increased in a time-dependent manner as high-glucose cells progressed in the lipogenic phase. In contrast, the activity decreased in low-glucose cells that did not accumulate lipids. An analysis of the subcellular localization of the PA phosphatase activity showed that the membrane-associated activity increased during lipogenesis. The significance of this increase can be explained by the fact that only the membrane-associated PA phosphatase activity is responsible for the production of DAG. Taken together, these results indicate that PA phosphatase is involved in TAG biosynthesis during lipogenesis in Y. lipolytica.

Glutamate dehydrogenases in the oleaginous yeast Yarrowia lipolytica

“…For plates, 1.5–2% agar was added. To test enzyme activity under nitrogen starvation, cells were cultured in medium with 50‐mM phosphate buffer (pH 6.8) and 8% glucose (Hardman, Ukey, & Fakas, ). To test growth on different carbon and nitrogen sources, 1% sodium glutamate was added to replace NH 4 Cl to give glucose/glutamate medium or to replace both NH 4 Cl and glucose to give glutamate/glutamate medium.…”

“…For plates, 1.5-2% agar was added. To test enzyme activity under nitrogen starvation, cells were cultured in medium with 50-mM phosphate buffer (pH 6.8) and 8% glucose (Hardman, Ukey, & Fakas, 2018)…”

The Yarrowia lipolytica PAH1 homologue contributes but is not required for triacylglycerol biosynthesis during growth on glucose

“…In Y. lipolytica, PAP activity is regulated by high glucose (Hardman, Ukey, & Fakas, 2018) and by growth phase (Hardman, McFalls, & Fakas, 2017). This activity is highly expressed in the exponential phase of growth, but it levels off as cells progress to the stationary phase of growth (Hardman et al, 2017).…”