Article

Mechanisms of cytokinesis in budding yeast

Institute of Chemistry and Biochemistry, Laboratory of Membrane Biochemistry and Molecular Cell Biology, Freie Universität Berlin, Takustraβe 6, Berlin, Germany.
Cytoskeleton (Impact Factor: 3.12). 10/2012; 69(10):710-26. DOI: 10.1002/cm.21046
Source: PubMed

ABSTRACT

Cytokinesis is essential for cell proliferation in all domains of life. Because the core components and mechanisms of cytokinesis are conserved from fungi to humans, the budding yeast Saccharomyces cerevisiae has served as an attractive model for studying this fundamental process. Cytokinesis in budding yeast is driven by two interdependent cellular events: actomyosin ring (AMR) constriction and the formation of a chitinous cell wall structure called the primary septum (PS), the functional equivalent of extracellular matrix remodeling during animal cytokinesis. AMR constriction is thought to drive efficient plasma membrane ingression as well as to guide PS formation, whereas PS formation is thought to stabilize the AMR during its constriction. Following the completion of the PS formation, two secondary septa (SS), consisting of glucans and mannoproteins, are synthesized at both sides of the PS. Degradation of the PS and a part of the SS by a chitinase and glucanases then enables cell separation. In this review, we discuss the mechanics of cytokinesis in budding yeast, highlighting its common and unique features as well as the emerging questions. © 2012 Wiley Periodicals, Inc.

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Available from: Erfei Bi, Dec 12, 2014
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    • "The fungal septum is a structure elaborated during cell division, simultaneously with the completion of cytokinesis , to form a physical boundary between the two progeny (reviewed by Walther & Wendland, 2003; Howell & Lew, 2012; Wloka & Bi, 2012; Mouriño-Pérez, 2013). Its composition and structure vary among the larger taxonomic groups, but the major components are polysaccharides. "
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    ABSTRACT: The post-cytokinetic separation of cells in cell-walled organisms involves enzymatic processes that degrade a specific layer of the division septum and the region of the mother cell wall that edges the septum. In the fission yeast Schizosaccharomyces pombe, the α-1,3-glucanase Agn1p, originally identified as a mutanase-like glycoside hydrolase family 71 enzyme, dissolves the mother cell wall around the septum edge. Our search in the genomes of completely sequenced fungi identified GH71 hydrolases in Basidiomycota, Taphrinomycotina and Pezizomycotina but not in Saccharomycotina. The most likely Agn1p orthologues in Pezizomycotina species are not mutanases having mutanase-binding domains but experimentally non-characterised hypothetical proteins that have no carbohydrate-binding domains. The analysis of the GH71 domains corroborated the phylogenetic relationships of the Schizosaccharomyces species determined by previous studies, but suggested a closer relationship to the Basidiomycota proteins than to the Ascomycota proteins. In the Schizosaccharomyces genus the Agn1p proteins are structurally conserved: their GH71 domains are flanked by N-terminal secretion signals and C-terminal sequences containing the conserved block YNFNAY/HTG. The inactivation of the agn1(Sj) gene in S. japonicus, the only true dimorphic member of the genus, caused a severe cell separation defect in its yeast phase but had no effect on the hyphal growth and yeast-to-mycelium transition. It did not affect the mycelium-to-yeast transition either, only delayed the separation of the yeast cells arising from the fragmenting hyphae. The heterologous expression of agn1(Sj) partially rescued the separation defect of the agn1Δ cells of S. pombe. The results presented indicate that the fission yeast Agn1p α-1,3-glucanases of S. japonicus and S. pombe share conserved functions in the yeast phase.
    Preview · Article · Apr 2014 · Microbiology
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    • "In the budding yeast Saccharomyces cerevisiae, cytokinesis involves actomyosin contractile ring closure and septum formation at the mother–bud neck (Bi et al., 1998). The actomyosin ring contains actin filaments formed by formin-dependent processes (Fang et al., 2010; Wloka and Bi, 2012). "
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    ABSTRACT: While actomyosin and septin ring organization and function in cytokinesis are thoroughly described, little is known regarding the mechanisms whereby the actomyosin ring interacts with septins and associated proteins to coordinate cell division. Here, we show that the protein product of YPL158C, Aim44p, undergoes septin-dependent recruitment to the site of cell division. Aim44p colocalizes with Myo1p, the type II myosin of the contractile ring, throughout most of the cell cycle. The Aim44p ring does not contract when the actomyosin ring closes. Instead, it forms a double ring that associates with septin rings on mother and daughter cells after cell separation. Deletion of AIM44 results in defects in contractile ring closure. Aim44p coimmunoprecipitates with Hof1p, a conserved F-BAR protein that binds both septins and type II myosins and promotes contractile ring closure. Deletion of AIM44 results in a delay in Hof1p phosphorylation, and altered Hof1p localization. Finally, overexpression of Dbf2p, a kinase that phosphorylates Hof1p and is required for relocalization of Hof1p from septin rings to the contractile ring and for Hof1p-triggered contractile ring closure, rescues the cytokinesis defect observed in aim44 cells. Our studies reveal a novel role for Aim44p in regulating contractile ring closure through effects on Hof1p.
    Full-text · Article · Jan 2014 · Molecular biology of the cell
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    • "during cleavage-furrow ingression Cyk3 was originally identified as a dosage suppressor of iqg1 (Korinek et al., 2000), and its overexpression has been found to promote PS formation in both wild-type and mutant (hof1, myo1, inn1, and a hypomorphic chs2 mutation) strains (our unpublished data; Nishihama et al., 2009; Oh et al., 2012; Wloka and Bi, 2012). Subsequent studies have shown that binding of the SH3 domain and PXXP motifs of Cyk3 to Inn1 and Hof1, respectively, is important for PS formation (unpublished data; Nishihama et al., 2009; Meitinger et al., 2011). "
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    ABSTRACT: In yeast and animal cytokinesis, the small guanosine triphosphatase (GTPase) Rho1/RhoA has an established role in formation of the contractile actomyosin ring, but its role, if any, during cleavage-furrow ingression and abscission is poorly understood. Through genetic screens in yeast, we found that either activation of Rho1 or inactivation of another small GTPase, Cdc42, promoted secondary septum (SS) formation, which appeared to be responsible for abscission. Consistent with this hypothesis, a dominant-negative Rho1 inhibited SS formation but not cleavage-furrow ingression or the concomitant actomyosin ring constriction. Moreover, Rho1 is temporarily inactivated during cleavage-furrow ingression; this inactivation requires the protein Cyk3, which binds Rho1-guanosine diphosphate via its catalytically inactive transglutaminase-like domain. Thus, unlike the active transglutaminases that activate RhoA, the multidomain protein Cyk3 appears to inhibit activation of Rho1 (and thus SS formation), while simultaneously promoting cleavage-furrow ingression through primary septum formation. This work suggests a general role for the catalytically inactive transglutaminases of fungi and animals, some of which have previously been implicated in cytokinesis.
    Full-text · Article · Jul 2013 · The Journal of Cell Biology
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