title: Regulated degradation of a class V myosin receptor directs movement of the yeast vacuole.
abstract: Normal cellular function requires that organelles be positioned in specific locations. The direction in which molecular motors move organelles is based in part on the polarity of microtubules and actin filaments. However, this alone does not determine the intracellular destination of organelles. For example, the yeast class V myosin, Myo2p, moves several organelles to distinct locations during the cell cycle. Thus the movement of each type of Myo2p cargo must be regulated uniquely. Here we report a regulatory mechanism that specifically provides directionality to vacuole movement. The vacuole-specific Myo2p receptor, Vac17p, has a key function in this process. Vac17p binds simultaneously to Myo2p and to Vac8p, a vacuolar membrane protein. The transport complex, Myo2p-Vac17p-Vac8p, moves the vacuole to the bud, and is then disrupted through the degradation of Vac17p. The vacuole is ultimately deposited near the centre of the bud. Removal of a PEST sequence (a potential signal for rapid protein degradation) within Vac17p causes its stabilization and the subsequent 'backward' movement of vacuoles, which mis-targets them to the neck between the mother cell and the bud. Thus the regulated disruption of this transport complex places the vacuole in its proper location. This may be a general mechanism whereby organelles are deposited at their terminal destination.
authors.affiliation: Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Fusheng
authors.initials: F
authors.lastname: Tang
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Kauffman
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Novak
authors.forename: Johnathan J
authors.initials: JJ
authors.lastname: Nau
authors.forename: Natalie L
authors.initials: NL
authors.lastname: Catlett
authors.forename: Lois S
authors.initials: LS
authors.lastname: Weisman
mesh_terms: D020816:Amino Acid Motifs; D002453:Cell Cycle; D048429:Cell Size; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D018995:Myosin Heavy Chains / Q000378:metabolism*; D024701:Myosin Type V / Q000378:metabolism*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism*; D033921:Vesicular Transport Proteins
chemical_list: D008074:Lipoproteins; C077512:MYO2 protein, S cerevisiae; D046911:Macromolecular Substances; D008565:Membrane Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D029701:Saccharomyces cerevisiae Proteins; C472499:VAC17 protein, S cerevisiae; C111373:VAC8 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D024701:Myosin Type V; D018995:Myosin Heavy Chains