Shs1 Plays Separable Roles in Septin Organization and Cytokinesis in <i>Saccharomyces cerevisiae</i>

Iwase, Masayuki; Luo, Juan; Bi, Erfei; Toh‐e, Akio

doi:10.1534/genetics.107.073007

Cited by 51 publications

(83 citation statements)

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“…On galactose medium and at 25°, cells lacking Cdc10 are able to survive , but, we found that, under the same conditions, such cells were not viable if they also lacked Shs1 ( Figure 1C, top middle), confirming an observation made by Iwase et al (2007). Either Shs1 or Shs1-eGFP was able to restore viability ( Figure S1B).…”

Section: Shs1 Is Essential For Viability In Four Different Genetic Basupporting

confidence: 75%

“…By contrast, absence of the fifth, mitotically expressed septin gene SHS1, a close paralog of CDC11 (Pan et al 2007), causes rather minor and subtle phenotypes (Iwase et al 2007;Egelhofer et al 2008;Garcia et al 2011;Buttery et al 2012). We explored whether compromising the function of another septin might provide a sensitized genetic background wherein presence of Shs1 becomes essential for viability.…”

Section: Shs1 Is Essential For Viability In Four Different Genetic Bamentioning

confidence: 99%

“…Two of them, SPR3 and SPR28, encode proteins expressed exclusively in MATa/MATa cells and only under conditions that induce meiosis and sporulation (Neiman 2011;Brar et al 2012). The third, SHS1/ SEP7 (Carroll et al 1998;Mino et al 1998), encodes a protein expressed in mitotically growing haploids and diploids, but, unlike loss of Cdc3, Cdc10, Cdc11, or Cdc12, even the complete absence of Shs1 seemed to have only a very modest effect on cell growth and morphology (Iwase et al 2007;Garcia et al 2011). Biochemical and ultrastructural analysis demonstrated that Shs1 occupies the same terminal position in the linear hetero-octamer as Cdc11, and that such Shs1-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Shs1 rods do not polymerize into long-paired filaments in vitro, but rather assemble into much more elaborate structures (rings, spirals, and gauzes, depending on the conditions) .…”

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confidence: 99%

“…Remarkably, however, in a strain background where cells lacking Cdc11 are dead, cdc11D shs1D double mutants are viable and, to survive, require that the resulting heterohexamers polymerize via a nonnative Cdc12-Cdc12 interaction . Conversely, in a strain background where cdc11D cells are able to propagate, overexpression of SHS1 kills them, but not otherwise isogenic CDC11 + cells (Iwase et al 2007). These results indicate that Shs1-capped hetero-octamers alone are not sufficient for viability and, when no competing Cdc11 is present, Shs1 caps the Cdc12 subunit and prevents polymerization of Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12 complexes, in agreement with the observation that Shs1-capped rods are unable to assemble into filaments in vitro .…”

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confidence: 99%

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Comprehensive Genetic Analysis of Paralogous Terminal Septin Subunits Shs1 and Cdc11 inSaccharomyces cerevisiae

et al. 2015

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Septins are a family of GTP-binding proteins considered to be cytoskeletal elements because they self-assemble into filaments and other higher-order structures in vivo. In budding yeast, septins establish a diffusion barrier at the bud neck between a mother and daughter cell, promote membrane curvature there, and serve as a scaffold to recruit other proteins to the site of cytokinesis. However, the mechanism by which any septin engages a partner protein has been unclear. The two most related and recently evolved subunits appear to be Cdc11 and Shs1, and the basic building blocks for assembling septin structures are hetero-octameric rods (Cdc11-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Cdc11 and Shs1-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Shs1). Loss of Cdc11 is not normally tolerated, whereas cells lacking Shs1 do not appear grossly abnormal. We established several different sensitized genetic backgrounds wherein Shs1 is indispensable, which allowed us to carry out the first comprehensive and detailed genetic analysis of Shs1 in vivo. Our analysis revealed several novel insights, including: (i) the sole portion of Shs1 essential for its function is a predicted coiled-coil-forming segment in its C-terminal extension (CTE); (ii) the CTE of Cdc11 shares this function; (iii) this role for the CTEs of Cdc11 and Shs1 is quite distinct from that of the CTEs of Cdc3 and Cdc12; and (iv) heterotypic Cdc11 and Shs1 junctions likely occur in vivo. KEYWORDS yeast; cytoskeleton; complexes; filaments; mutants S EPTINS are GTP-binding proteins conserved across Eukarya (except higher plants) (Pan et al. 2007;Nishihama et al. 2011). This protein family was first identified because the corresponding loci were among the temperature-sensitive (ts) cell division cycle (cdc) mutations isolated in Saccharomyces cerevisiae (Hartwell 1978). At the restrictive temperature, cdc3, cdc10, cdc11, and cdc12 mutants continued to bud, replicate, and segregate their chromosomes, yet failed to execute cell division, resulting in the formation of chains of multinucleate cells (Hartwell 1971). Shifting a ts allele of any of these four homologous gene products to restrictive temperature prevented formation of what appeared to be rings of highly ordered membrane-associated filaments at the bud neck (Byers and Goetsch 1976). Antibody decoration (Haarer and Pringle 1987;Ford and Pringle 1991;Kim et al. 1991) and, later, use of fusions to green fluorescent protein (GFP) (Cid et al. 1998) demonstrated that these four proteins colocalized with and were likely constituents of these filaments. Because loss of the function of these proteins prevents cytokinesis and cell septation, and they seemed to be integral components of the filamentous structures erected at the bud neck, they were dubbed septins (Sanders and Field 1994;Pringle 2008). Indeed, subsequent purification of these proteins from yeast (Frazier et al. 1998), and their production as recombinant proteins in bacteria Versele and Thorner 2004;Farkasovsky et al. 2005), demonstrated that Cdc3, Cdc10, Cdc11...

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Section: Shs1 Is Essential For Viability In Four Different Genetic Basupporting

confidence: 75%

Section: Shs1 Is Essential For Viability In Four Different Genetic Bamentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Comprehensive Genetic Analysis of Paralogous Terminal Septin Subunits Shs1 and Cdc11 inSaccharomyces cerevisiae

et al. 2015

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“…Alternatively timely expression during the cell cycle might be compromised (Beilharz and Preiss 2007). The process of septin assembly is sensitive to protein levels, for example overexpression of the septins compromises cell morphology and septin organization (Sopko et al 2006;Iwase et al 2007) and therefore higher levels of septins and/or septin assembly factors could lead to septin organization defects.…”

Section: Resultsmentioning

confidence: 99%

The Ccr4-Pop2-NOT mRNA Deadenylase Contributes to Septin Organization in Saccharomyces cerevisiae

Traven

Beilharz

et al. 2009

Genetics

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In yeast, assembly of the septins at the cell cortex is required for a series of key cell cycle events: bud-site selection, the morphogenesis and mitotic exit checkpoints, and cytokinesis. Here we establish that the Ccr4-Pop2-NOT mRNA deadenylase contributes to septin organization. mRNAs encoding regulators of septin assembly (Ccd42, Cdc24, Rga1, Rga2, Bem3, Gin4, Cla4, and Elm1) presented with short poly(A) tails at steady state in wild-type (wt) cells, suggesting their translation could be restricted by deadenylation. Deadenylation of septin regulators was dependent on the major cellular mRNA deadenylase Ccr4-Pop2-NOT, whereas the alternative deadenylase Pan2 played a minor role. Consistent with deadenylation of septin regulators being important for function, deletion of deadenylase subunits CCR4 or POP2, but not PAN2, resulted in septin morphology defects (e.g., ectopic bud-localized septin rings), particularly upon activation of the Cdc28-inhibitory kinase Swe1. Aberrant septin staining was also observed in the deadenylase-dead ccr4-1 mutant, demonstrating the deadenylase activity of Ccr4-Pop2 is required. Moreover, ccr4D, pop2D, and ccr4-1 mutants showed aberrant cell morphology previously observed in septin assembly mutants and exhibited genetic interactions with mutations that compromise septin assembly (shs1D, cla4D, elm1D, and gin4D). Mutations in the Not subunits of Ccr4-Pop2-NOT, which are thought to predominantly function in transcriptional control, also resulted in septin organization defects. Therefore, both mRNA deadenylase and transcriptional functions of Ccr4-Pop2-NOT contribute to septin organization in yeast.

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Septin mutations and phenotypes in S. cerevisiae

Mela

Momany

2018

Cytoskeleton

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Septins are highly conserved guanosine triphosphate (GTP)-binding proteins that are a component of the cytoskeletal systems of virtually all eukaryotes (except higher plants). Septins play important roles in a multitude of cellular processes, including cytokinesis, establishment of cell polarity, and cellular partitioning. The ease of genetic screens and a fully sequenced genome have made Saccharomyces cerevisiae one of the most extensively studied and well-annotated model organisms in eukaryotic biology. Here, we present a synopsis of the known point mutations in the seven S. cerevisiae septin genes: CDC3, CDC10, CDC11, CDC12, SHS1, SPR3, and SPR28. We map these mutations onto septin protein structures, highlighting important conserved motifs, and relating the functional consequences of mutations in each domain.

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Shs1 Plays Separable Roles in Septin Organization and Cytokinesis in Saccharomyces cerevisiae

Cited by 51 publications

References 64 publications

Comprehensive Genetic Analysis of Paralogous Terminal Septin Subunits Shs1 and Cdc11 inSaccharomyces cerevisiae

Comprehensive Genetic Analysis of Paralogous Terminal Septin Subunits Shs1 and Cdc11 inSaccharomyces cerevisiae

The Ccr4-Pop2-NOT mRNA Deadenylase Contributes to Septin Organization in Saccharomyces cerevisiae

Septin mutations and phenotypes in S. cerevisiae

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