A Yeast Mutant Deleted of GPH1 Bears Defects in Lipid Metabolism

• Published in: PloS one 2015-09, Vol.10 (9), p.e0136957-e0136957
• Main Authors: Gsell, Martina, Fankl, Ariane, Klug, Lisa, Mascher, Gerald, Schmidt, Claudia, Hrastnik, Claudia, Zellnig, Günther, Daum, Günther
• Format: Article
• Language: English
• Subjects: Baking yeast; Biochemistry; Biodegradation; Biosynthesis; Cell Membrane - genetics; Cell Membrane - metabolism; Choline; Chromosome deletion; Cytidine Diphosphate Choline - genetics; Cytidine Diphosphate Choline - metabolism; Depletion; Energy; Esters; Esters - metabolism; Gene deletion; Gene expression; Gene Expression Regulation, Fungal - genetics; Gene mutation; Genes, Fungal - genetics; Genetic aspects; Glycogen; Glycogen - genetics; Glycogen - metabolism; Glycogen phosphorylase; Health aspects; Lecithin; Lipid metabolism; Lipid Metabolism - genetics; Lipids; Metabolism; Methylation; Mitochondria; Mutation; Mutation - genetics; Phosphatidylcholine; Phosphatidylcholines - genetics; Phosphatidylcholines - metabolism; Phosphatidylethanolamine; Phosphatidylserine; Phosphatidylserine decarboxylase; Phosphatidylserine decarboxylase 1; Phosphorylase; Phosphorylation; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Stability; Triglycerides; Triglycerides - genetics; Triglycerides - metabolism; Yeast; Yeasts (Fungi); Yeasts - genetics; Yeasts - metabolism
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0136957

In a previous study we demonstrated up-regulation of the yeast GPH1 gene under conditions of phosphatidylethanolamine (PE) depletion caused by deletion of the mitochondrial (M) phosphatidylserine decarboxylase 1 (PSD1) (Gsell et al., 2013, PLoS One. 8(10):e77380. doi: 10.1371/journal.pone.0077380). Gph1p has originally been identified as a glycogen phosphorylase catalyzing degradation of glycogen to glucose in the stationary growth phase of the yeast. Here we show that deletion of this gene also causes decreased levels of phosphatidylcholine (PC), triacylglycerols and steryl esters. Depletion of the two non-polar lipids in a Δgph1 strain leads to lack of lipid droplets, and decrease of the PC level results in instability of the plasma membrane. In vivo labeling experiments revealed that formation of PC via both pathways of biosynthesis, the cytidine diphosphate (CDP)-choline and the methylation route, is negatively affected by a Δgph1 mutation, although expression of genes involved is not down regulated. Altogether, Gph1p besides its function as a glycogen mobilizing enzyme appears to play a regulatory role in yeast lipid metabolism.