title: Degradation of Hof1 by SCF(Grr1) is important for actomyosin contraction during cytokinesis in yeast.
abstract: SCF-type (SCF: Skp1-Cullin-F-box protein complex) E3 ligases regulate ubiquitin-dependent degradation of many cell cycle regulators, mainly at the G1/S transition. Here, we show that SCF(Grr1) functions during cytokinesis by degrading the PCH protein Hof1. While Hof1 is required early in mitosis to assemble a functional actomyosin ring, it is specifically degraded late in mitosis and remains unstable during the entire G1 phase of the cell cycle. Degradation of Hof1 depends on its PEST motif and a functional 26S proteasome. Interestingly, degradation of Hof1 is independent of APC(Cdh1), but instead requires the SCF(Grr1) E3 ligase. Grr1 is recruited to the mother-bud neck region after activation of the mitotic-exit network, and interacts with Hof1 in a PEST motif-dependent manner. Our results also show that downregulation of Hof1 at the end of mitosis is necessary to allow efficient contraction of the actomyosin ring and cell separation during cytokinesis. SCF(Grr1)-mediated degradation of Hof1 may thus represent a novel mechanism to couple exit from mitosis with initiation of cytokinesis.
authors.affiliation: CNRS, Station Biologique, UMR7150, Amyloids and Cell Division Cycle Laboratory, Place G Teissier, Roscoff, Bretagne, France. blondel@sb-roscoff.fr
authors.forename: Marc
authors.initials: M
authors.lastname: Blondel
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bach
authors.forename: Sophie
authors.initials: S
authors.lastname: Bamps
authors.forename: Jeroen
authors.initials: J
authors.lastname: Dobbelaere
authors.forename: Philippe
authors.initials: P
authors.lastname: Wiget
authors.forename: Céline
authors.initials: C
authors.lastname: Longaretti
authors.forename: Yves
authors.initials: Y
authors.lastname: Barral
authors.forename: Laurent
authors.initials: L
authors.lastname: Meijer
authors.forename: Matthias
authors.initials: M
authors.lastname: Peter
mesh_terms: D000205:Actomyosin / Q000378:metabolism*; D000595:Amino Acid Sequence; D015153:Blotting, Western; D048749:Cytokinesis / Q000502:physiology*; D044783:F-Box Proteins; D016193:G1 Phase / Q000502:physiology*; D040461:Gene Components; D049452:Green Fluorescent Proteins; D006207:Half-Life; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D015003:Yeasts
chemical_list: D044783:F-Box Proteins; C116847:HOF1 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; C071032:GRR1 protein, S cerevisiae; D049452:Green Fluorescent Proteins; D000205:Actomyosin; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease