title: Control of protein and sterol trafficking by antagonistic activities of a type IV P-type ATPase and oxysterol binding protein homologue.
abstract: The oxysterol binding protein homologue Kes1p has been implicated in nonvesicular sterol transport in Saccharomyces cerevisiae. Kes1p also represses formation of protein transport vesicles from the trans-Golgi network (TGN) through an unknown mechanism. Here, we show that potential phospholipid translocases in the Drs2/Dnf family (type IV P-type ATPases [P4-ATPases]) are downstream targets of Kes1p repression. Disruption of KES1 suppresses the cold-sensitive (cs) growth defect of drs2Delta, which correlates with an enhanced ability of Dnf P4-ATPases to functionally substitute for Drs2p. Loss of Kes1p also suppresses a drs2-ts allele in a strain deficient for Dnf P4-ATPases, suggesting that Kes1p antagonizes Drs2p activity in vivo. Indeed, Drs2-dependent phosphatidylserine translocase (flippase) activity is hyperactive in TGN membranes from kes1Delta cells and is potently attenuated by addition of recombinant Kes1p. Surprisingly, Drs2p also antagonizes Kes1p activity in vivo. Drs2p deficiency causes a markedly increased rate of cholesterol transport from the plasma membrane to the endoplasmic reticulum (ER) and redistribution of endogenous ergosterol to intracellular membranes, phenotypes that are Kes1p dependent. These data suggest a homeostatic feedback mechanism in which appropriately regulated flippase activity in the Golgi complex helps establish a plasma membrane phospholipid organization that resists sterol extraction by a sterol binding protein.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634, USA.
authors.forename: Baby-Periyanayaki
authors.initials: BP
authors.lastname: Muthusamy
authors.forename: Sumana
authors.initials: S
authors.lastname: Raychaudhuri
authors.forename: Paramasivam
authors.initials: P
authors.lastname: Natarajan
authors.forename: Fumiyoshi
authors.initials: F
authors.lastname: Abe
authors.forename: Ke
authors.initials: K
authors.lastname: Liu
authors.forename: William A
authors.initials: WA
authors.lastname: Prinz
authors.forename: Todd R
authors.initials: TR
authors.lastname: Graham
mesh_terms: D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D003080:Cold Temperature; D011992:Endosomes / Q000378:metabolism; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D008565:Membrane Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D021381:Protein Transport; D011987:Receptors, Steroid / Q000737:chemistry* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013261:Sterols / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology; D014617:Vacuoles / Q000378:metabolism; D021601:trans-Golgi Network / Q000201:enzymology; D000098825:Oxysterol Binding Proteins
chemical_list: C104014:DRS2 protein, S cerevisiae; C087901:KES1 protein, S cerevisiae; D008565:Membrane Proteins; D011987:Receptors, Steroid; D029701:Saccharomyces cerevisiae Proteins; D013261:Sterols; D000098825:Oxysterol Binding Proteins; D000252:Calcium-Transporting ATPases