title: Genetic interactions with mutations affecting septin assembly reveal ESCRT functions in budding yeast cytokinesis.
abstract: Membrane trafficking via targeted exocytosis to the Saccharomyces cerevisiae bud neck provides new membrane and membrane-associated factors that are critical for cytokinesis. It remains unknown whether yeast plasma membrane abscission, the final step of cytokinesis, occurs spontaneously following extensive vesicle fusion, as in plant cells, or requires dedicated membrane fission machinery, as in cultured mammalian cells. Components of the endosomal sorting complexes required for transport (ESCRT) pathway, or close relatives thereof, appear to participate in cytokinetic abscission in various cell types, but roles in cell division had not been documented in budding yeast, where ESCRTs were first characterized. By contrast, the septin family of filament-forming cytoskeletal proteins were first identified by their requirement for yeast cell division. We show here that mutations in ESCRT-encoding genes exacerbate the cytokinesis defects of cla4Δ or elm1Δ mutants, in which septin assembly is perturbed at an early stage in cell division, and alleviate phenotypes of cells carrying temperature-sensitive alleles of a septin-encoding gene, CDC10. Elevated chitin synthase II (Chs2) levels coupled with aberrant morphogenesis and chitin deposition in elm1Δ cells carrying ESCRT mutations suggest that ESCRTs normally enhance the efficiency of cell division by promoting timely endocytic turnover of key cytokinetic enzymes.
authors.affiliation: Division of Biochemistry and Molecular Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: McMurray
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Stefan
authors.forename: Megan
authors.initials: M
authors.lastname: Wemmer
authors.forename: Greg
authors.initials: G
authors.lastname: Odorizzi
authors.forename: Scott D
authors.initials: SD
authors.lastname: Emr
authors.forename: Jeremy
authors.initials: J
authors.lastname: Thorner
mesh_terms: D048749:Cytokinesis / Q000235:genetics / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis / Q000235:genetics / Q000502:physiology; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D005089:Exocytosis / Q000235:genetics / Q000502:physiology; D009154:Mutation; D004718:Saccharomycetales / Q000235:genetics / Q000378:metabolism*; D058112:Septins / Q000235:genetics / Q000378:metabolism*
chemical_list: D003598:Cytoskeletal Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D058112:Septins