Role of the Yeast Phosphatidylinositol/Phosphatidylcholine Transfer Protein (Sec14p) in Phosphatidylcholine Turnover andINO1 Regulation

Patton‐Vogt, Jana; Griač, Peter; Sreenivas, Avula; Bruno, Vincent M.; Dowd, Susan R.; Swede, Marci J.; Henry, Susan A.

doi:10.1074/jbc.272.33.20873

Cited by 122 publications

(144 citation statements)

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“…4A). The decrease in 32 P i incorporation into PC in the cki1⌬ eki1⌬ mutant reflected phospholipase D-mediated turnover of PC (41,81) and the inability to reutilize choline for PC synthesis via the Kennedy pathway. The cki1⌬ eki1⌬ mutations did not have a major effect on the steady state composition of phospholipids labeled with either 32 P i (Fig.…”

Section: Effect Of the Cki1⌬ Eki1⌬mentioning

confidence: 99%

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Regulation of Phospholipid Synthesis in the Yeast cki1Δ eki1Δ Mutant Defective in the Kennedy Pathway

Choi

Sreenivas

Han

et al. 2004

Journal of Biological Chemistry

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In the yeast Saccharomyces cerevisiae, the most abundant phospholipid phosphatidylcholine is synthesized by the complementary CDP-diacylglycerol and Kennedy pathways. Using a cki1⌬ eki1⌬ mutant defective in choline kinase and ethanolamine kinase, we examined the consequences of a block in the Kennedy pathway on the regulation of phosphatidylcholine synthesis by the CDP-diacylglycerol pathway. The cki1⌬ eki1⌬ mutant exhibited increases in the synthesis of phosphatidylserine, phosphatidylethanolamine, and phosphatidylcholine via the CDP-diacylglycerol pathway. The increase in phospholipid synthesis correlated with increased activity levels of the CDPdiacylglycerol pathway enzymes phosphatidylserine synthase, phosphatidylserine decarboxylase, phosphatidylethanolamine methyltransferase, and phospholipid methyltransferase. However, other enzyme activities, including phosphatidylinositol synthase and phosphatidate phosphatase, were not affected in the cki1⌬ eki1⌬ mutant. For phosphatidylserine synthase, the enzyme catalyzing the committed step in the pathway, activity was regulated by increases in the levels of mRNA and protein. Decay analysis of CHO1 mRNA indicated that a dramatic increase in transcript stability was a major component responsible for the elevated level of phosphatidylserine synthase. These results revealed a novel mechanism that controls phospholipid synthesis in yeast.PC 1 is the most abundant phospholipid in the membranes of eukaryotic cells (1-4). It serves as a structural component of the membrane and as a source of bioactive lipids (e.g. lyso-PC, PA, DAG) (1-5). The importance of PC is underscored by the fact that alterations in its metabolism are linked to apoptosis (6 -9) and oncogenic transformation (10 -12). In the model eukaryote Saccharomyces cerevisiae, PC is synthesized by complementary pathways that are common to those found in mammalian cells 2 ( Fig. 1) (1,4,(13)(14)(15)(16)(17). In the CDP-DAG pathway, PC is synthesized from CDP-DAG via the reactions catalyzed by PS synthase (18 -20), PS decarboxylase (21-23), PE methyltransferase (24, 25), and phospholipid methyltransferase (24,26). In the CDP-choline branch of the Kennedy pathway, PC is synthesized from choline via the reactions catalyzed by choline kinase (27), phosphocholine cytidylyltransferase (28), and choline phosphotransferase (29,30). Analyses of mutations in S. cerevisiae (4, 31, 32), as well as in mammalian cells (33,34) indicate that the physiological role(s) of PC synthesized by the two pathways are different.The contribution of the CDP-DAG and Kennedy pathways for PC synthesis in wild type S. cerevisiae is dependent on the exogenous supply of choline (35). When grown in the presence of choline, yeast primarily synthesizes PC via the Kennedy pathway (35). On the other hand, when cells are grown in the absence of choline, PC is primarily synthesized via the CDP-DAG pathway (35). Yet, even under this growth condition, the Kennedy pathway still contributes to the synthesis of PC (36 -41). The choline required for the Kenne...

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Section: Effect Of the Cki1⌬ Eki1⌬mentioning

confidence: 99%

“…Yet, even under this growth condition, the Kennedy pathway still contributes to the synthesis of PC (36 -41). The choline required for the Kennedy pathway is derived from the phospholipase D-mediated turnover of PC synthesized via the CDP-DAG pathway (41,42).…”

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confidence: 99%

Regulation of Phospholipid Synthesis in the Yeast cki1Δ eki1Δ Mutant Defective in the Kennedy Pathway

Choi

Sreenivas

Han

et al. 2004

Journal of Biological Chemistry

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“…Strains carrying mutations in the CDP-choline pathway, such as cki1, in combination with a temperature-sensitive sec14 mutation, exhibit a dramatically increased choline secretion phenotype. 201 Thus, Sec14p appears to be involved in formation of phosphatidic acid (PA) through an interplay with phospholipase D1 (Pld1p)-catalysed degradation of PtdCho. 251 Alternatively, it was proposed that Sec14p may be required to maintain a sufficient pool of diacylglycerol in the Golgi to support the production of secretory vesicles.…”

Section: Phospholipid Synthesismentioning

confidence: 99%

Biochemistry, cell biology and molecular biology of lipids ofSaccharomyces cerevisiae

Daum

Lees

Bard

et al. 1998

Yeast

580

380

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The yeast Saccharomyces cerevisiae is a powerful experimental system to study biochemical, cell biological and molecular biological aspects of lipid synthesis. Most but not all genes encoding enzymes involved in fatty acid, phospholipid, sterol or sphingolipid biosynthesis of this unicellular eukaryote have been cloned, and many gene products have been functionally characterized. Less information is available about genes and gene products governing the transport of lipids between organelles and within membranes, turnover and degradation of complex lipids, regulation of lipid biosynthesis, and linkage of lipid metabolism to other cellular processes. Here we summarize current knowledge about lipid biosynthetic pathways in S. cerevisiae and describe the characteristic features of the gene products involved. We focus on recent discoveries in these fields and address questions on the regulation of lipid synthesis, subcellular localization of lipid biosynthetic steps, cross‐talk between organelles during lipid synthesis and subcellular distribution of lipids. Finally, we discuss distinct functions of certain key lipids and their possible roles in cellular processes. © 1998 John Wiley & Sons, Ltd.

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“…In the absence of exogenous choline, wild type cells synthesize PC by both the CDP-choline and CDP-diacylglycerol pathways (17, 30, 69 -71). The choline required for the CDP-choline pathway is derived from the phospholipase D-mediated turnover of PC synthesized via the CDP-diacylglycerol pathway (71,72). We examined the composition of phospholipids by labeling cells with both 32 P i and [methyl-3 H]choline.…”

Section: Ctp Synthetase Synthetic Peptides Containing a Proteinmentioning

confidence: 99%

Phosphorylation of CTP Synthetase on Ser36, Ser330, Ser354, and Ser454 Regulates the Levels of CTP and Phosphatidylcholine Synthesis in Saccharomyces cerevisiae

Park

O'Brien

Carman

2003

Journal of Biological Chemistry

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The Saccharomyces cerevisiae URA7-encoded CTP synthetase is phosphorylated and stimulated by protein kinase C. We examined the hypothesis that Ser 36 , Ser 330 , Ser 354 , and Ser 454 , contained in a protein kinase C sequence motif in CTP synthetase, were target sites for the kinase. Synthetic peptides containing a phosphorylation motif at these serine residues served as substrates for protein kinase C in vitro. Ser 3 Ala (S36A, S330A, S354A, and S454A) mutations in CTP synthetase were constructed by site-directed mutagenesis and expressed normally in a ura7 ura8 double mutant that lacks CTP synthetase activity. The CTP synthetase activity in extracts from cells bearing the S36A, S354A, and S454A mutant enzymes was reduced when compared with cells bearing the wild type enzyme. Kinetic analysis of purified mutant enzymes showed that the S36A and S354A mutations caused a decrease in the V max of the reaction. This regulation could be attributed in part by the effects phosphorylation has on the nucleotide-dependent oligomerization of CTP synthetase. In contrast, CTP synthetase activity in cells bearing the S330A mutant enzyme was elevated, and kinetic analysis of purified enzyme showed that the S330A mutation caused an elevation in the V max of the reaction. In vitro data indicated that phosphorylation of CTP synthetase at Ser 330 affected the phosphorylation of the enzyme at another site. The phosphorylation of CTP synthetase at Ser 36 , Ser 330 , Ser 354 , and Ser 454 residues was physiologically relevant. Cells bearing the S36A, S354A, and S454A mutations had reduced CTP levels, whereas cells with the S330A mutation had elevated CTP levels. The alterations in CTP levels correlated with the regulatory effects CTP has on the pathways responsible for the synthesis of the membrane phospholipid phosphatidylcholine.In the yeast Saccharomyces cerevisiae CTP synthetase catalyzes the ATP-dependent transfer of the amide nitrogen of glutamine to the C-4 position of UTP to form CTP (1, 2). GTP stimulates the reaction by accelerating the formation of a covalent glutaminyl enzyme catalytic intermediate (2-5). URA7 (6) and URA8 (7) are duplicate genes that code for CTP synthetase in S. cerevisiae. The yeast CTP synthetase enzymes (6, 7) contain a conserved glutamine amide transfer domain (see Fig. 1) common to CTP synthetases from other organisms (8 -16). The URA7-encoded CTP synthetase is more abundant than the URA8-encoded enzyme (17) and is responsible for the majority of the CTP synthesized in vivo (7). Neither the URA7 nor the URA8 gene is essential as long as cells possess one functional CTP synthetase gene (6, 7). CTP synthetase is an indispensable enzyme because its reaction product CTP is essential for the synthesis of nucleic acids and membrane phospholipids (18). The importance of understanding the regulation of CTP synthetase is emphasized by the fact that unregulated levels of its activity is a common property of various cancers in humans (19 -26).The yeast CTP synthetase is regulated by genetic and biochemical m...

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Role of the Yeast Phosphatidylinositol/Phosphatidylcholine Transfer Protein (Sec14p) in Phosphatidylcholine Turnover andINO1 Regulation

Cited by 122 publications

References 49 publications

Regulation of Phospholipid Synthesis in the Yeast cki1Δ eki1Δ Mutant Defective in the Kennedy Pathway

Regulation of Phospholipid Synthesis in the Yeast cki1Δ eki1Δ Mutant Defective in the Kennedy Pathway

Biochemistry, cell biology and molecular biology of lipids ofSaccharomyces cerevisiae

Phosphorylation of CTP Synthetase on Ser36, Ser330, Ser354, and Ser454 Regulates the Levels of CTP and Phosphatidylcholine Synthesis in Saccharomyces cerevisiae

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