title: A monitor for bud emergence in the yeast morphogenesis checkpoint.
abstract: Cell cycle transitions are subject to regulation by both external signals and internal checkpoints that monitor satisfactory progression of key cell cycle events. In budding yeast, the morphogenesis checkpoint arrests the cell cycle in response to perturbations that affect the actin cytoskeleton and bud formation. Herein, we identify a step in this checkpoint pathway that seems to be directly responsive to bud emergence. Activation of the kinase Hsl1p is dependent upon its recruitment to a cortical domain organized by the septins, a family of conserved filament-forming proteins. Under conditions that delayed or blocked bud emergence, Hsl1p recruitment to the septin cortex still took place, but hyperphosphorylation of Hsl1p and recruitment of the Hsl1p-binding protein Hsl7p to the septin cortex only occurred after bud emergence. At this time, the septin cortex spread to form a collar between mother and bud, and Hsl1p and Hsl7p were restricted to the bud side of the septin collar. We discuss models for translating cellular geometry (in this case, the emergence of a bud) into biochemical signals regulating cell proliferation.
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Chandra L
authors.initials: CL
authors.lastname: Theesfeld
authors.forename: Trevin R
authors.initials: TR
authors.lastname: Zyla
authors.forename: Elaine G S
authors.initials: EG
authors.lastname: Bardes
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Lew
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D003001:Cloning, Molecular; D004789:Enzyme Activation; D009024:Morphogenesis; D010766:Phosphorylation; D010957:Plasmids; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011484:Protein-Arginine N-Methyltransferases; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D018797:Cell Cycle Proteins; D029701:Saccharomyces cerevisiae Proteins; D011484:Protein-Arginine N-Methyltransferases; C120666:HSL7 protein, S cerevisiae; D011494:Protein Kinases; C099685:SWE1 protein, S cerevisiae; D011505:Protein-Tyrosine Kinases; C106494:HSL1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases