title: Deleting the DAG kinase Dgk1 augments yeast vacuole fusion through increased Ypt7 activity and altered membrane fluidity.
abstract: Diacylglycerol (DAG) is a fusogenic lipid that can be produced through phospholipase C activity on phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], or through phosphatidic acid (PA) phosphatase activity. The fusion of Saccharomyces cerevisiae vacuoles requires DAG, PA and PI(4,5)P2, and the production of these lipids is thought to provide temporally specific stoichiometries that are critical for each stage of fusion. Furthermore, DAG and PA can be interconverted by the DAG kinase Dgk1 and the PA phosphatase Pah1. Previously we found that pah1 Δ vacuoles were fragmented, blocked in SNARE priming and showed arrested endosomal maturation. In other pathways the effects of deleting PAH1 can be compensated for by additionally deleting DGK1 ; however, deleting both genes did not rescue the pah1 Δ vacuolar defects. Deleting DGK1 alone caused a marked increase in vacuole fusion that was attributed to elevated DAG levels. This was accompanied by a gain in resistance to the inhibitory effects of PA as well as inhibitors of Ypt7 activity. Together these data show that Dgk1 function can act as a negative regulator of vacuole fusion through the production of PA at the cost of depleting DAG and reducing Ypt7 activity.
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Miner
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Starr
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Logan R
authors.initials: LR
authors.lastname: Hurst
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois.|Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Rutilio A
authors.initials: RA
authors.lastname: Fratti
mesh_terms: D019852:Diacylglycerol Kinase / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism; D008560:Membrane Fluidity / Q000502:physiology*; D008561:Membrane Fusion / Q000502:physiology; D010711:Phosphatidate Phosphatase / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D012097:Repressor Proteins / Q000378:metabolism*; D050600:SNARE Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D014617:Vacuoles; D033921:Vesicular Transport Proteins / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: C434524:DGK1 protein, S cerevisiae; D018129:Phosphatidylinositol Phosphates; D012097:Repressor Proteins; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D019852:Diacylglycerol Kinase; D010711:Phosphatidate Phosphatase; C079005:YPT7 protein, S cerevisiae; D020691:rab GTP-Binding Proteins
keywords: 
  SNARE
  ; Dgk1; Mon1-Ccz1; Pah1; Rab7; Vam7; Yck3; Ypt7; diacylglycerol; lipin-1; membrane fusion; phosphatidic acid