title: Fluorescence spectroscopy measures yeast PAH1-encoded phosphatidate phosphatase interaction with liposome membranes.
abstract: Phosphatidate (PA) phosphatase, the enzyme that catalyzes the penultimate step in triacylglycerol synthesis, is a cytosolic enzyme that must associate with the membrane where its substrate PA resides. Fluorescence spectroscopy was used to measure the interaction of yeast PAH1-encoded PA phosphatase with model liposome membranes. PA phosphatase contains five tryptophan residues and exhibited inherit fluorescence that increased upon interaction with phosphatidylcholine liposomes. The interaction was enhanced by inclusion of other phospholipids and especially the substrate PA. Interaction was dependent on both the concentration of phosphatidylcholine-PA liposomes as well as the surface concentration of PA in liposomes. Mg(2+) ions, which were required for catalysis, did not affect PA phosphatase interaction with phosphatidylcholine-PA liposomes. PA phosphatase was a substrate for protein kinase A, protein kinase C, and casein kinase II, and these phosphorylations decreased PA phosphatase interaction with phosphatidylcholine-PA liposome membranes.
authors.affiliation: Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901.
authors.forename: Wen-Min
authors.initials: WM
authors.lastname: Su
authors.affiliation: Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901. Electronic address: carman@aesop.rutgers.edu.
authors.forename: George M
authors.initials: GM
authors.lastname: Carman
mesh_terms: D008081:Liposomes / Q000378:metabolism*; D010711:Phosphatidate Phosphatase / Q000235:genetics / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D008081:Liposomes; D010743:Phospholipids; D029701:Saccharomyces cerevisiae Proteins; D014280:Triglycerides; D010711:Phosphatidate Phosphatase