title: Mitotic phosphorylation of Exo84 disrupts exocyst assembly and arrests cell growth.
abstract: The rate of eukaryotic cell growth is tightly controlled for proper progression through each cell cycle stage and is important for cell size homeostasis. It was previously shown that cell growth is inhibited during mitosis when cells are preparing for division. However, the mechanism for growth arrest at this stage is unknown. Here we demonstrate that exocytosis of a select group of cargoes was inhibited before the metaphase-anaphase transition in the budding yeast Saccharomyces cerevisiae. The cyclin-dependent kinase, Cdk1, when bound to the mitotic cyclin Clb2, directly phosphorylated Exo84, a component of the exocyst complex essential for exocytosis. Mitotic phosphorylation of Exo84 disrupted the assembly of the exocyst complex, thereby affecting exocytosis and cell surface expansion. Our study demonstrates the coordination between membrane trafficking and cell cycle progression and provides a molecular mechanism by which cell growth is controlled during the cell division cycle.
authors.affiliation: Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Guangzuo
authors.initials: G
authors.lastname: Luo
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Francis C
authors.initials: FC
authors.lastname: Luca
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
mesh_terms: D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism; D059447:Cell Cycle Checkpoints; D053144:Cell Nucleus Shape; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D005089:Exocytosis; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000235:genetics / Q000378:metabolism; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D025941:Protein Interaction Mapping; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: C093749:CLB2 protein, S cerevisiae; D019926:Cyclin B; C120810:EXO84 protein, S cerevisiae; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D016203:CDC2 Protein Kinase; C080389:BGL2 protein, S cerevisiae; D004693:Glucan Endo-1,3-beta-D-Glucosidase