title: Yeast vacuolar HOPS, regulated by its kinase, exploits affinities for acidic lipids and Rab:GTP for membrane binding and to catalyze tethering and fusion.
abstract: Fusion of yeast vacuoles requires the Rab GTPase Ypt7p, four SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors), the SNARE disassembly chaperones Sec17p/Sec18p, vacuolar lipids, and the Rab-effector complex HOPS (homotypic fusion and vacuole protein sorting). Two HOPS subunits have direct affinity for Ypt7p. Although vacuolar fusion has been reconstituted with purified components, the functional relationships between individual lipids and Ypt7p:GTP have remained unclear. We now report that acidic lipids function with Ypt7p as coreceptors for HOPS, supporting membrane tethering and fusion. After phosphorylation by the vacuolar kinase Yck3p, phospho-HOPS needs both Ypt7p:GTP and acidic lipids to support fusion.
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755 amy.orr@dartmouth.edu william.t.wickner@dartmouth.edu michael.zick@dartmouth.edu.
authors.forename: Amy
authors.initials: A
authors.lastname: Orr
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755 amy.orr@dartmouth.edu william.t.wickner@dartmouth.edu michael.zick@dartmouth.edu.
authors.forename: William
authors.initials: W
authors.lastname: Wickner
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755.
authors.forename: Scott F
authors.initials: SF
authors.lastname: Rusin
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755 Norris Cotton Cancer Center, Lebanon, NH 03756.
authors.forename: Arminja N
authors.initials: AN
authors.lastname: Kettenbach
authors.affiliation: Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755.
authors.forename: Michael
authors.initials: M
authors.lastname: Zick
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D047389:Casein Kinase I / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D015151:Immunoblotting; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008561:Membrane Fusion; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism; D050765:Qa-SNARE Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25 / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D008081:Liposomes; D008563:Membrane Lipids; D021122:Protein Subunits; D050765:Qa-SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D050825:Synaptosomal-Associated Protein 25; C107706:VAM3 protein, S cerevisiae; C406817:VAM6 protein, S cerevisiae; C494205:VAM7 protein, S cerevisiae; C083878:VPS41 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D006160:Guanosine Triphosphate; D047389:Casein Kinase I; C479667:YCK3 protein, S cerevisiae; C079005:YPT7 protein, S cerevisiae; D020691:rab GTP-Binding Proteins