scholarly journals Fission Yeast Pob1p, Which Is Homologous to Budding Yeast Boi Proteins and Exhibits Subcellular Localization Close to Actin Patches, Is Essential for Cell Elongation and Separation

1999 ◽  
Vol 10 (8) ◽  
pp. 2745-2757 ◽  
Author(s):  
Mika Toya ◽  
Yuichi Iino ◽  
Masayuki Yamamoto
Keyword(s):  
Cell Growth ◽  
Fission Yeast ◽  
Cell Separation ◽  
Gene Disruption ◽  
Host Cells ◽  
Ph Domain ◽  
Division Plane ◽  
Sam Domain ◽  
Growing Cell ◽  
Growth Loss

The fission yeast pob1 gene encodes a protein of 871 amino acids carrying an SH3 domain, a SAM domain, and a PH domain. Gene disruption and construction of a temperature-sensitivepob1 mutant indicated that pob1 is essential for cell growth. Loss of its function leads to quick cessation of cellular elongation. Pob1p is homologous to two functionally redundant Saccharomyces cerevisiaeproteins, Boi1p and Boi2p, which are necessary for cell growth and relevant to bud formation. Overexpression of pob1inhibits cell growth, causing the host cells to become round and swollen. In growing cells, Pob1p locates at cell tips during interphase and translocates near the division plane at cytokinesis. Thus, this protein exhibits intracellular dynamics similar to F-actin patches. However, Pob1p constitutes a layer, rather than patches, at growing cell tips. It generates two split discs flanking the septum at cytokinesis. The pob1-defective cells no longer elongate but swell gradually at the middle, eventually assuming a lemon-like morphology. Analysis using the pob1-ts allele revealed that Pob1p is also essential for cell separation. We speculate that Pob1p is located on growing plasma membrane, possibly through the function of actin patches, and may recruit proteins required for the synthesis of cell wall.

The Cofactor-Dependent Pathways for α- and β-Tubulins in Microtubule Biogenesis Are Functionally Different in Fission Yeast

Genetics ◽  
2000 ◽  
Vol 156 (1) ◽  
pp. 93-103
Author(s):  
Pippa A Radcliffe ◽  
Miguel Angel Garcia ◽  
Takashi Toda
Keyword(s):  
Protein Folding ◽  
Cell Growth ◽  
Genetic Analysis ◽  
Cell Viability ◽  
Detailed Analysis ◽  
Fission Yeast ◽  
Gene Disruption ◽  
Genetic Interactions ◽  
Evolutionarily Conserved ◽  
Β Tubulin

Abstract The biogenesis of microtubules in the cell comprises a series of complex steps, including protein-folding reactions catalyzed by chaperonins. In addition a group of evolutionarily conserved proteins, called cofactors (A to E), is required for the production of assembly-competent α-/β-tubulin heterodimers. Using fission yeast, in which alp11+, alp1+, and alp21+, encoding the homologs for cofactors B, D, and E, respectively, are essential for cell viability, we have undertaken the genetic analysis of alp31+, the homolog of cofactor A. Gene disruption analysis shows that, unlike the three genes mentioned above, alp31+ is dispensable for cell growth and division. Nonetheless, detailed analysis of alp31-deleted cells demonstrates that Alp31A is required for the maintenance of microtubule structures and, consequently, the proper control of growth polarity. alp31-deleted cells show genetic interactions with mutations in β-tubulin, but not in α-tubulin. Budding yeast cofactor A homolog RBL2 is capable of suppressing the polarity defects of alp31-deleted cells. We conclude that the cofactor-dependent biogenesis of microtubules comprises an essential and a nonessential pathway, both of which are required for microtubule integrity.

scholarly journals Pob1 Participates in the Cdc42 Regulation of Fission Yeast Actin Cytoskeleton

2009 ◽  
Vol 20 (20) ◽  
pp. 4390-4399 ◽  
Author(s):  
Sergio A. Rincón ◽  
Yanfang Ye ◽  
M. Antonia Villar-Tajadura ◽  
Beatriz Santos ◽  
Sophie G. Martin ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Fission Yeast ◽  
Mutant Strain ◽  
Rho Gtpases ◽  
Ph Domain ◽  
Actin Organization ◽  
Multicopy Suppressor ◽  
Sam Domain ◽  
Actin Cable ◽  
Actin Cables

Rho GTPases regulate the actin cytoskeleton in all eukaryotes. Fission yeast Cdc42 is involved in actin cable assembly and formin For3 regulation. We isolated cdc42-879 as a thermosensitive strain with actin cable and For3 localization defects. In a multicopy suppressor screening, we identified pob1+as suppressor of cdc42-879 thermosensitivity. Pob1 overexpression also partially restores actin cables and localization of For3 in the mutant strain. Pob1 interacts with Cdc42 and this GTPase regulates Pob1 localization and/or stability. The C-terminal pleckstrin homology (PH) domain of Pob1 is required for Cdc42 binding. Pob1 also binds to For3 through its N-terminal sterile alpha motif (SAM) domain and contributes to the formin localization at the cell tips. The previously described pob1-664 mutant strain (Mol. Biol. Cell. 10, 2745–2757, 1999), which carries a mutation in the PH domain, as well as pob1 mutant strains in which Pob1 lacks the N-terminal region (pob1ΔN) or the SAM domain (pob1ΔSAM), have cytoskeletal defects similar to that of cdc42-879 cells. Expression of constitutively active For3DAD* partially restores actin organization in cdc42-879, pob1-664, pob1ΔN, and pob1ΔSAM. Therefore, we propose that Pob1 is required for For3 localization to the tips and facilitates Cdc42-mediated relief of For3 autoinhibition to stimulate actin cable formation.

scholarly journals Calcium spikes accompany cleavage furrow ingression and cell separation during fission yeast cytokinesis

2021 ◽  
Vol 32 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Abhishek Poddar ◽  
Oumou Sidibe ◽  
Aniruddha Ray ◽  
Qian Chen
Keyword(s):  
Fission Yeast ◽  
Cell Separation ◽  
Cleavage Furrow ◽  
Cell Integrity ◽  
Embryonic Cells ◽  
Contractile Ring ◽  
Calcium Spikes ◽  
Division Plane ◽  
Ring Constriction ◽  
And Function

Calcium rises transiently at the division plane during cytokinesis of embryonic cells, but the conservation and function of such calcium transients remain unclear. We discovered similar calcium spikes during fission yeast cytokinesis, and demonstrated that calcium promotes contractile ring constriction and daughter cell integrity.

scholarly journals Mcp5, a meiotic cell cortex protein, is required for nuclear movement mediated by dynein and microtubules in fission yeast

2006 ◽  
Vol 173 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Takamune T. Saito ◽  
Daisuke Okuzaki ◽  
Hiroshi Nojima
Keyword(s):  
Fission Yeast ◽  
Meiotic Prophase ◽  
Coiled Coil ◽  
Cell Cortex ◽  
Ph Domain ◽  
Nuclear Movement ◽  
Recombination Rates ◽  
Homologous Chromosome Pairing ◽  
Cortical Localization ◽  
Pulling Force

During meiotic prophase I of the fission yeast Schizosaccharomyces pombe, oscillatory nuclear movement occurs. This promotes homologous chromosome pairing and recombination and involves cortical dynein, which plays a pivotal role by generating a pulling force with the help of an unknown dynein anchor. We show that Mcp5, the homologue of the budding yeast dynein anchor Num1, may be this putative dynein anchor. mcp5+ is predominantly expressed during meiotic prophase, and GFP-Mcp5 localizes at the cell cortex. Moreover, the mcp5Δ strain lacks the oscillatory nuclear movement. Accordingly, homologous pairing and recombination rates of the mcp5Δ strain are significantly reduced. Furthermore, the cortical localization of dynein heavy chain 1 appears to be reduced in mcp5Δ cells. Finally, the full function of Mcp5 requires its coiled-coil and pleckstrin homology (PH) domains. Our results suggest that Mcp5 localizes at the cell cortex through its PH domain and functions as a dynein anchor, thereby facilitating nuclear oscillation.

scholarly journals Genome-wide screen for cell growth regulators in fission yeast

2017 ◽  
Vol 130 (12) ◽  
pp. 2049-2055 ◽  
Author(s):  
Louise Weston ◽  
Jessica Greenwood ◽  
Paul Nurse
Keyword(s):  
Cell Growth ◽  
Fission Yeast ◽  
Growth Regulators ◽  
Genome Wide

The cell cycle of symbiotic Chlorella. I. The relationship between host feeding and algal cell growth and division

1985 ◽  
Vol 77 (1) ◽  
pp. 225-239
Author(s):  
P.J. McAuley
Keyword(s):  
Cell Division ◽  
Cell Growth ◽  
Host Cell ◽  
Algal Cell ◽  
Host Cells ◽  
Digestive Cell ◽  
Host Feeding ◽  
Digestive Cells ◽  
Division Factor ◽  
Cell Mitosis

When green hydra were starved, cell division of the symbiotic algae within their digestive cells was inhibited, but algal cell growth, measured as increase in either mean volume or protein content per cell, was not. Therefore, control of algal division by the host digestive cells must be effected by direct inhibition of algal mitosis rather than by controlling algal cell growth. The number of algae per digestive cell increased slightly during starvation, eventually reaching a new stable level. A number of experiments demonstrated that although there was a relationship between host cell and algal mitosis, this was not causal: the apparent entrainment of algal mitosis to that of the host cells could be disrupted. Thus, there was a delay in algal but not host cell mitosis when hydra were fed after prolonged starvation, and algae repopulated starved hydra with lower than normal numbers of algae (reinfected aposymbionts or hydra transferred to light after growth in continuous darkness). Two experiments demonstrated a direct stimulation of algal cell division by host feeding. Relationships of algal and host cell mitosis to numbers of Artemia digested per hydra were different, and in hydra fed extracted Artemia algal, but not host cell, mitosis was reduced in comparison to that in control hydra fed live shrimp. It is proposed that algal division may be dependent on a division factor, derived from host digestion of prey, whose supply is controlled by the host cells. Numbers of algae per cell would be regulated by competition for division factor, except at host cell mitosis, when the algae may have temporarily uncontrolled access to host pools of division factor. The identity of the division factor is not known, but presumably is a metabolite needed by both host cells and algae.

Wachstumsparameter in normalen und durch Actinomycin verlängerten Zellzyklen von Tetrahymena / Growth Parameters in Normal and Actinomycin-induced prolonged Cell Cycles of Tetrahymena

1969 ◽  
Vol 24 (12) ◽  
pp. 1624-1629 ◽  
Author(s):  
Günter Cleffmann
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Cell Division ◽  
Dna Replication ◽  
Cell Growth ◽  
Rna Synthesis ◽  
Growth Parameters ◽  
Average Duration ◽  
Cell Cycles ◽  
Growing Cell

Actinomycin in low concentration (0,2 μg/ml — 0,5 μg/ml) prolongs the average duration of the cell cycle of Tetrahymena considerably, but does not inhibit cell division completely. Some parameters of the growing cell have been tested in cell cycles extended in this way and compared to those of normally growing cells. The RNA synthesis of treated cells is reduced to such an extent that the RNA content per cell decreases during the prolonged cell cycle. Nevertheless cell growth, protein synthesis and DNA replication proceed at almost the same rate as in untreated cells. These findings indicate that the presence of actinomycin does not interfere with RNA fractions necessary for growth but reduce the synthesis of RNA fractions which are essential for cell division. Therefore a longer period is needed for their accumulation.

scholarly journals Scw1p Antagonizes the Septation Initiation Network To Regulate Septum Formation and Cell Separation in the Fission Yeast Schizosaccharomyces pombe

2003 ◽  
Vol 2 (3) ◽  
pp. 510-520 ◽  
Author(s):  
Quan-Wen Jin ◽  
Dannel McCollum
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Cell Separation ◽  
Deletion Mutant ◽  
Temperature Sensitive ◽  
Growth Defects ◽  
Septum Formation ◽  
Primary Septum ◽  
Septation Initiation Network ◽  
Ring Constriction

ABSTRACT Cytokinesis in the fission yeast Schizosaccharomyces pombe is regulated by a signaling pathway termed the septation initiation network (SIN). The SIN is essential for initiation of actomyosin ring constriction and septum formation. In a screen to search for mutations that can rescue the sid2-250 SIN mutant, we obtained scw1-18. Both the scw1-18 mutant and the scw1 deletion mutant (scw1Δ mutant), have defects in cell separation. Both the scw1-18 and scw1Δ mutations rescue the growth defects of not just the sid2-250 mutant but also the other temperature-sensitive SIN mutants. Other cytokinesis mutants, such as those defective for actomyosin ring formation, are not rescued by scw1Δ. scw1Δ does not seem to rescue the SIN by restoring SIN signaling defects. However, scw1Δ may function downstream of the SIN to promote septum formation, since scw1Δ can rescue the septum formation defects of the cps1-191β-1,3-glucan synthase mutant, which is required for synthesis of the primary septum.

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