title: Genomic analysis of homotypic vacuole fusion.
abstract: Yeast vacuoles undergo fission and homotypic fusion, yielding one to three vacuoles per cell at steady state. Defects in vacuole fusion result in vacuole fragmentation. We have screened 4828 yeast strains, each with a deletion of a nonessential gene, for vacuole morphology defects. Fragmented vacuoles were found in strains deleted for genes encoding known fusion catalysts as well as 19 enzymes of lipid metabolism, 4 SNAREs, 12 GTPases and GTPase effectors, 9 additional known vacuole protein-sorting genes, 16 protein kinases, 2 phosphatases, 11 cytoskeletal proteins, and 28 genes of unknown function. Vacuole fusion and vacuole protein sorting are catalyzed by distinct, but overlapping, sets of proteins. Novel pathways of vacuole priming and docking emerged from this deletion screen. These include ergosterol biosynthesis, phosphatidylinositol (4,5)-bisphosphate turnover, and signaling from Rho GTPases to actin remodeling. These pathways are supported by the sensitivity of the late stages of vacuole fusion to inhibitors of phospholipase C, calcium channels, and actin remodeling. Using databases of yeast protein interactions, we found that many nonessential genes identified in our deletion screen interact with essential genes that are directly involved in vacuole fusion. Our screen reveals regulatory pathways of vacuole docking and provides a genomic basis for studies of this reaction.
authors.affiliation: Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755-3844, USA.
authors.forename: E Scott
authors.initials: ES
authors.lastname: Seeley
authors.forename: Masashi
authors.initials: M
authors.lastname: Kato
authors.forename: Nathan
authors.initials: N
authors.lastname: Margolis
authors.forename: William
authors.initials: W
authors.lastname: Wickner
authors.forename: Gary
authors.initials: G
authors.lastname: Eitzen
mesh_terms: D005456:Fluorescent Dyes / Q000378:metabolism; D005656:Fungal Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D008561:Membrane Fusion / Q000235:genetics* / Q000502:physiology; D005810:Multigene Family; D016366:Open Reading Frames / Q000235:genetics; D011726:Pyridinium Compounds / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D014617:Vacuoles / Q000378:metabolism*; D015003:Yeasts / Q000166:cytology / Q000235:genetics* / Q000378:metabolism
chemical_list: C092350:FM 4-64; D005456:Fluorescent Dyes; D005656:Fungal Proteins; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds