scholarly journals Role of the α-Glucanase Agn1p in Fission-Yeast Cell Separation

2004 ◽  
Vol 15 (8) ◽  
pp. 3903-3914 ◽  
Author(s):  
Nick Dekker ◽  
Dave Speijer ◽  
Christian H. Grün ◽  
Marlene van den Berg ◽  
Annett de Haan ◽  
...  
Keyword(s):  
Cell Division ◽  
Fission Yeast ◽  
Cell Separation ◽  
Wall Material ◽  
Dependent Manner ◽  
Cellular Functions ◽  
Daughter Cells ◽  
Primary Septum ◽  
Cycle Dependent ◽  
Division Cell

Cell division in the fission yeast Schizosaccharomyces pombe yields two equal-sized daughter cells. Medial fission is achieved by deposition of a primary septum flanked by two secondary septa within the dividing cell. During the final step of cell division, cell separation, the primary septum is hydrolyzed by an endo-(1,3)-β-glucanase, Eng1p. We reasoned that the cell wall material surrounding the septum, referred to here as the septum edging, also must be hydrolyzed before full separation of the daughter cells can occur. Because the septum edging contains (1,3)-α-glucan, we investigated the cellular functions of the putative (1,3)-α-glucanases Agn1p and Agn2p. Whereas agn2 deletion results in a defect in endolysis of the ascus wall, deletion of agn1 leads to clumped cells that remained attached to each other by septum-edging material. Purified Agn1p hydrolyzes (1,3)-α-glucan predominantly into pentasaccharides, indicating an endo-catalytic mode of hydrolysis. Furthermore, we show that the transcription factors Sep1p and Ace2p regulate both eng1 and agn1 expression in a cell cycle-dependent manner. We propose that Agn1p acts in concert with Eng1p to achieve efficient cell separation, thereby exposing the secondary septa as the new ends of the daughter cells.

Influence of cell-wall thickness on cell division: electron microscopic study with Bacillus cereus

1973 ◽  
Vol 19 (2) ◽  
pp. 217-221 ◽  
Author(s):  
K. L. Chung
Keyword(s):  
Cell Division ◽  
Bacillus Cereus ◽  
Wall Thickness ◽  
Cell Separation ◽  
Thick Layer ◽  
Wall Material ◽  
Cross Wall ◽  
Electron Microscopic ◽  
Daughter Cells ◽  
The Cross

Bacillus cereus that had been exposed to chloramphenicol for 0 and 90 min synthesized walls whose thickness increased with time. These cells were washed and resuspended in fresh growth medium. Cell division was examined by electron microscopy. In untreated cells, a slight invagination of the cytoplasmic membrane with deposit of cross-wall material marked the onset of cell division. The cross wall grew inward until the septum was about [Formula: see text] completed. This was followed by splitting and bifurcation of the outer edge of the cross wall, which in turn separated the peripheral wall scars. Cross-wall penetration with further splitting continued until the daughter cells were completely partitioned. The peripheral wall scars that were located at the junction of peripheral and end walls at the time of cell separation indicated that the zone of cell division was probably not a region of active cell elongation. In cells treated with chloramphenicol for 90 min, cross-wall initiation and completion all occurred beneath a thickened peripheral wall. The circumferential portion of the peripheral wall at the zone of cell division appeared to be responsible for the hindrance of cell separation. This thick layer subsequently severed at three or four sites to allow the separation of daughter cells. For cells that had initiated cross-wall invagination at the time when chloramphenicol was added, accumulation of a large amount of cross-wall material at the zone of cell division was observed. Upon removal of the antibiotic, cells abandoned the old and initiated a new dividing site. For cells that had already completed cross-wall formation at the time of chloramphenicol treatment, the increase in wall thickness did not appear to interfere with cell separation. Models for the different stages of cell division in all these bacteria were presented.

scholarly journals An anillin homologue, Mid2p, acts during fission yeast cytokinesis to organize the septin ring and promote cell separation

2003 ◽  
Vol 160 (7) ◽  
pp. 1093-1103 ◽  
Author(s):  
Joseph J. Tasto ◽  
Jennifer L. Morrell ◽  
Kathleen L. Gould
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Fission Yeast ◽  
Cell Separation ◽  
Cell Cycle Progression ◽  
Dependent Manner ◽  
Septin Ring ◽  
Protein Levels ◽  
Division Site ◽  
Cell Biol

Anillin is a conserved protein required for cell division (Field, C.M., and B.M. Alberts. 1995. J. Cell Biol. 131:165–178; Oegema, K., M.S. Savoian, T.J. Mitchison, and C.M. Field. 2000. J. Cell Biol. 150:539–552). One fission yeast homologue of anillin, Mid1p, is necessary for the proper placement of the division site within the cell (Chang, F., A. Woollard, and P. Nurse. 1996. J. Cell Sci. 109(Pt 1):131–142; Sohrmann, M., C. Fankhauser, C. Brodbeck, and V. Simanis. 1996. Genes Dev. 10:2707–2719). Here, we identify and characterize a second fission yeast anillin homologue, Mid2p, which is not orthologous with Mid1p. Mid2p localizes as a single ring in the middle of the cell after anaphase in a septin- and actin-dependent manner and splits into two rings during septation. Mid2p colocalizes with septins, and mid2Δ cells display disorganized, diffuse septin rings and a cell separation defect similar to septin deletion strains. mid2 gene expression and protein levels fluctuate during the cell cycle in a sep1- and Skp1/Cdc53/F-box (SCF)–dependent manner, respectively, implying that Mid2p activity must be carefully regulated. Overproduction of Mid2p depolarizes cell growth and affects the organization of both the septin and actin cytoskeletons. In the presence of a nondegradable Mid2p fragment, the septin ring is stabilized and cell cycle progression is delayed. These results suggest that Mid2p influences septin ring organization at the site of cell division and its turnover might normally be required to permit septin ring disassembly.

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.

scholarly journals The Gene Expression and Enzyme Activity of Plant 3-Deoxy-D-Manno-2-Octulosonic Acid-8-Phosphate Synthase Are Preferentially Associated with Cell Division in a Cell Cycle-Dependent Manner

2003 ◽  
Vol 133 (1) ◽  
pp. 348-360 ◽  
Author(s):  
Frédéric Delmas ◽  
Johann Petit ◽  
Jérôme Joubès ◽  
Martial Séveno ◽  
Thomas Paccalet ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Enzyme Activity ◽  
Cell Division ◽  
Dependent Manner ◽  
A Cell ◽  
Cycle Dependent ◽  
Phosphate Synthase

Cdc42 reactivation at growth sites is regulated by local cell-cycle-dependent loss of its GAP Rga4

2021 ◽  
Author(s):  
Julie Rich-Robinson ◽  
Afton Russell ◽  
Eleanor Mancini ◽  
Maitreyi Das
Keyword(s):  
Cell Cycle ◽  
Cell Separation ◽  
Fixed Time ◽  
Negative Regulator ◽  
Dependent Manner ◽  
Polarized Growth ◽  
A Cell ◽  
Local Cell ◽  
Cycle Dependent ◽  
Anaphase B

In fission yeast, polarized cell growth stops during division and resumes after cytokinesis completes and cells separate. It is unclear how growth reactivation is timed to occur immediately after cell separation. We uncoupled these sequential events by delaying cytokinesis with a temporary Latrunculin A treatment. Mitotic cells recovering from treatment initiate end growth during septation, displaying a polar elongation simultaneous with septation (PrESS) phenotype. PrESS cell ends reactivate Cdc42, a major regulator of polarized growth, during septation, but at a fixed time after anaphase B. A candidate screen implicates Rga4, a negative regulator of Cdc42, in this process. We show that Rga4 appears punctate at the cell sides during G2, but is diffuse during mitosis, extending to the ends. While the Morphogenesis Orb6 (MOR) pathway is known to promote cell separation and growth by activating protein synthesis, we find that for polarized growth, removal of Rga4 from the ends is also necessary. Therefore, we propose that growth resumes after division once the MOR pathway is activated and the ends lose Rga4 in a cell-cycle-dependent manner.

scholarly journals EGT2 gene transcription is induced predominantly by Swi5 in early G1.

1996 ◽  
Vol 16 (7) ◽  
pp. 3264-3274 ◽  
Author(s):  
B Kovacech ◽  
K Nasmyth ◽  
T Schuster
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Cell Separation ◽  
S Phase ◽  
Dependent Manner ◽  
Yeast Saccharomyces Cerevisiae ◽  
Concentration Dependent Manner ◽  
A Cell ◽  
Cycle Dependent ◽  
Ho Gene

In a screen for cell cycle-regulated genes in the yeast Saccharomyces cerevisiae, we have identified a gene, EGT2, which is involved in cell separation in the G1 stage of the cell cycle. Transcription of EGT2 is tightly regulated in a cell cycle-dependent manner. Transcriptional levels peak at the boundary of mitosis and early G1 The transcription factors responsible for EGT2 expression in early G1 are Swi5 and, to a lesser extent, Ace2. Swi5 is involved in the transcriptional activation of the HO gene during late G1 and early S phase, and Ace2 induces CTS1 transcription during early and late G1 We show that Swi5 activates EGT2 transcription as soon as it enters the nucleus at the end of mitosis in a concentration-dependent manner. Since Swi5 is unstable in the nucleus, its level drops rapidly, causing termination of EGT2 transcription before cells are committed to the next cell cycle. However, Swi5 is still able to activate transcription of HO in late G1 in conjunction with additional activators such as Swi4 and Swi6.

scholarly journals The Meiosis-Specific Sid2p-related Protein Slk1p Regulates Forespore Membrane Assembly in Fission Yeast

2008 ◽  
Vol 19 (9) ◽  
pp. 3676-3690 ◽  
Author(s):  
Hongyan Yan ◽  
Wanzhong Ge ◽  
Ting Gang Chew ◽  
Jeng Yeong Chow ◽  
Dannel McCollum ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Essential Role ◽  
Spindle Pole ◽  
Dependent Manner ◽  
Related Protein ◽  
Membrane Assembly ◽  
Daughter Cells ◽  
Spindle Pole Bodies ◽  
Septation Initiation Network ◽  
Secretory Apparatus

Cytokinesis in all organisms involves the creation of membranous barriers that demarcate individual daughter cells. In fission yeast, a signaling module termed the septation initiation network (SIN) plays an essential role in the assembly of new membranes and cell wall during cytokinesis. In this study, we have characterized Slk1p, a protein-kinase related to the SIN component Sid2p. Slk1p is expressed specifically during meiosis and localizes to the spindle pole bodies (SPBs) during meiosis I and II in a SIN-dependent manner. Slk1p also localizes to the forespore membrane during sporulation. Cells lacking Slk1p display defects associated with sporulation, leading frequently to the formation of asci with smaller and/or fewer spores. The ability of slk1Δ cells to sporulate, albeit inefficiently, is fully abolished upon compromise of function of Sid2p, suggesting that Slk1p and Sid2p play overlapping roles in sporulation. Interestingly, increased expression of the syntaxin Psy1p rescues the sporulation defect of sid2-250 slk1Δ. Thus, it is likely that Slk1p and Sid2p play a role in forespore membrane assembly by facilitating recruitment of components of the secretory apparatus, such as Psy1p, to allow membrane expansion. These studies thereby provide a novel link between the SIN and vesicle trafficking during cytokinesis.

scholarly journals Cdc42 promotes Bgs1 recruitment for septum synthesis and glucanase localization for cell separation during cytokinesis in fission yeast

2019 ◽  
Author(s):  
Udo N. Onwubiko ◽  
Julie Robinson ◽  
Rose Albu Mustaf ◽  
Maitreyi E. Das
Keyword(s):  
Fission Yeast ◽  
Membrane Trafficking ◽  
Cell Separation ◽  
Nucleotide Exchange ◽  
Timely Initiation ◽  
Division Site ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Primary Septum ◽  
Ring Constriction

AbstractCytokinesis in fission yeast involves actomyosin ring constriction concurrent to septum synthesis followed by septum digestion resulting in cell separation. A recent report indicates that endocytosis is required for septum synthesis and cell separation. The conserved GTPase Cdc42 is required for membrane trafficking and promotes endocytosis. Cdc42 is activated by Guanine nucleotide exchange factors (GEFs). Cdc42 GEFs have been shown to promote timely initiation of septum synthesis and proper septum morphology. Here we show that Cdc42 promotes the recruitment of the major primary septum synthesizing enzyme Bgs1 and consequent ring constriction. Cdc42 is also required for proper localization of the septum digesting glucanases at the division site. Thus, Cdc42 is required to promote multiple steps during cytokinesis.

scholarly journals imp2, a New Component of the Actin Ring in the Fission Yeast Schizosaccharomyces pombe

1998 ◽  
Vol 143 (2) ◽  
pp. 415-427 ◽  
Author(s):  
Janos Demeter ◽  
Shelley Sazer
Keyword(s):  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Model Organism ◽  
Eukaryotic Cell ◽  
Actin Ring ◽  
Daughter Cells ◽  
Isolation And Characterization ◽  
Ring Structures

Cytokinesis is the part of the cell cycle in which the cell is cleaved to form two daughter cells. The unicellular yeast, Schizosaccharomyces pombe is an excellent model organism in which to study cell division, since it shows the general features of eukaryotic cell division and is amenable to genetic analysis. In this manuscript we describe the isolation and characterization of a new protein, imp2, which is required for normal septation in fission yeast. imp2, which colocalizes with the medial ring during septation, is structurally similar to a group of proteins including the S. pombe cdc15 and the mouse PSTPIP that are localized to, and thought to be involved in actin ring organization. Cells in which the imp2 gene is deleted or overexpressed have septation and cell separation defects. An analysis of the actin cytoskeleton shows the lack of a medial ring in septating cells that overexpress imp2, and the appearance of abnormal medial ring structures in septated cells that lack imp2. These observations suggest that imp2 destabilizes the medial ring during septation. imp2 also shows genetic interactions with several, previously characterized septation genes, strengthening the conclusion that it plays a role in normal fission yeast septation.

scholarly journals Chromokinesin KIF4A teams up with stathmin 1 to regulate abscission in a SUMO-dependent manner

2020 ◽  
Vol 133 (14) ◽  
pp. jcs248591
Author(s):  
Sabine A. G. Cuijpers ◽  
Edwin Willemstein ◽  
Jan G. Ruppert ◽  
Daphne M. van Elsland ◽  
William C. Earnshaw ◽  
...  
Keyword(s):  
Cell Division ◽  
Acceptor Site ◽  
Dependent Manner ◽  
Intercellular Bridge ◽  
Dynamic Interactions ◽  
Post Translational Modifications ◽  
Sumo Modification ◽  
Daughter Cells ◽  
Sumo Conjugation ◽  
Stathmin 1

ABSTRACTCell division ends when two daughter cells physically separate via abscission, the cleavage of the intercellular bridge. It is not clear how the anti-parallel microtubule bundles bridging daughter cells are severed. Here, we present a novel abscission mechanism. We identified chromokinesin KIF4A, which is adjacent to the midbody during cytokinesis, as being required for efficient abscission. KIF4A is regulated by post-translational modifications. We evaluated modification of KIF4A by the ubiquitin-like protein SUMO. We mapped lysine 460 in KIF4A as the SUMO acceptor site and employed CRISPR-Cas9-mediated genome editing to block SUMO conjugation of endogenous KIF4A. Failure to SUMOylate this site in KIF4A delayed cytokinesis. SUMOylation of KIF4A enhanced the affinity for the microtubule destabilizer stathmin 1 (STMN1). We here present a new level of abscission regulation through the dynamic interactions between KIF4A and STMN1 as controlled by SUMO modification of KIF4A.

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