Altered Lipid Synthesis by Lack of Yeast Pah1 Phosphatidate Phosphatase Reduces Chronological Life Span.
In Saccharomyces cerevisiae, Pah1 phosphatidate phosphatase, which catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol, plays a crucial role in the synthesis of the storage lipid triacylglycerol. This evolutionarily conserved enzyme also plays a negative regulatory role in controlling de novo membrane phospholipid synthesis through its consumption of phosphatidate. We found that the pah1Δ mutant was defective in the utilization of non-fermentable carbon sources but not in oxidative phosphorylation; the mutant did not exhibit major changes in oxygen consumption rate, mitochondrial membrane potential, F1F0-ATP synthase activity, or gross mitochondrial morphology. The pah1Δ mutant contained an almost normal complement of major mitochondrial phospholipids with some alterations in molecular species. Although oxidative phosphorylation was not compromised in the pah1Δ mutant, the cellular levels of ATP in quiescent cells were reduced by 2-fold, inversely correlating with a 4-fold increase in membrane phospholipids. In addition, the quiescent pah1Δ mutant cells had 3-fold higher levels of mitochondrial superoxide and cellular lipid hydroperoxides, had reduced activities of superoxide dismutase 2 and catalase, and were hypersensitive to hydrogen peroxide. Consequently, the pah1Δ mutant had a shortened chronological life span. In addition, the loss of Tsa1 thioredoxin peroxidase caused a synthetic growth defect with the pah1Δ mutation. The shortened chronological life span of the pah1Δ mutant along with its growth defect on non-fermentable carbon sources and hypersensitivity to hydrogen peroxide was suppressed by the loss of Dgk1 diacylglycerol kinase, indicating that the underpinning of pah1Δ mutant defects was the excess synthesis of membrane phospholipids.
From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901.
Yeonhee
Y
Park
From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901.
Gil-Soo
GS
Han
the Department of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, Texas 77030, and.
Eugenia
E
Mileykovskaya
the Department of Chemistry, Vassar College, Poughkeepsie, New York 12604.
Teresa A
TA
Garrett
From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901, carman@aesop.rutgers.edu.
George M
GM
Carman
D000255:Adenosine Triphosphate / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D008055:Lipids / Q000096:biosynthesis*; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism; D018384:Oxidative Stress; D010101:Oxygen Consumption; D054464:Peroxiredoxins / Q000378:metabolism; D010711:Phosphatidate Phosphatase / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
D008055:Lipids; D029701:Saccharomyces cerevisiae Proteins; D002244:Carbon; D000255:Adenosine Triphosphate; D054464:Peroxiredoxins; C079831:PAH1 protein, S cerevisiae; D010711:Phosphatidate Phosphatase; C474451:F1F0-ATP synthase; D025261:Mitochondrial Proton-Translocating ATPases
diacylglycerol; phosphatidate; phospholipid; triacylglycerol; yeast