scholarly journals Mechanism of Cytokinetic Contractile Ring Constriction in Fission Yeast

2014 ◽  
Vol 29 (5) ◽  
pp. 547-561 ◽  
Author(s):  
Matthew R. Stachowiak ◽  
Caroline Laplante ◽  
Harvey F. Chin ◽  
Boris Guirao ◽  
Erdem Karatekin ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Contractile Ring ◽  
Ring Constriction

scholarly journals Fission yeast Cyk3p is a transglutaminase-like protein that participates in cytokinesis and cell morphogenesis

2012 ◽  
Vol 23 (13) ◽  
pp. 2433-2444 ◽  
Author(s):  
Luther W. Pollard ◽  
Masayuki Onishi ◽  
John R. Pringle ◽  
Matthew Lord
Keyword(s):  
Fission Yeast ◽  
Primary Role ◽  
Cell Integrity ◽  
Cell Morphogenesis ◽  
Contractile Ring ◽  
Physiological Importance ◽  
Complex Process ◽  
Catalytic Active Site ◽  
Thiol Proteases ◽  
Ring Constriction

Cell morphogenesis is a complex process that relies on a diverse array of proteins and pathways. We have identified a transglutaminase-like protein (Cyk3p) that functions in fission yeast morphogenesis. The phenotype of a cyk3 knockout strain indicates a primary role for Cyk3p in cytokinesis. Correspondingly, Cyk3p localizes both to the actomyosin contractile ring and the division septum, promoting ring constriction, septation, and subsequent cell separation following ring disassembly. In addition, Cyk3p localizes to polarized growth sites and plays a role in cell shape determination, and it also appears to contribute to cell integrity during stationary phase, given its accumulation as dynamic puncta at the cortex of such cells. Our results and the conservation of Cyk3p across fungi point to a role in cell wall synthesis and remodeling. Cyk3p possesses a transglutaminase domain that is essential for function, even though it lacks the catalytic active site. In a wider sense, our work illustrates the physiological importance of inactive members of the transglutaminase family, which are found throughout eukaryotes. We suggest that the proposed evolution of animal transglutaminase cross-linking activity from ancestral bacterial thiol proteases was accompanied by the emergence of a subclass whose function does not depend on enzymatic activity.

scholarly journals Contractile ring constriction and septation in fission yeast are integrated mutually stabilizing processes

2021 ◽  
Author(s):  
Sathish Thiyagarajan ◽  
Zachary A McDargh ◽  
Shuyuan Wang ◽  
Ben O'Shaughnessy
Keyword(s):  
Cell Wall ◽  
Fission Yeast ◽  
Growth Ring ◽  
Integrated System ◽  
Animal Cells ◽  
Contractile Ring ◽  
Cell Wall Growth ◽  
Ring Constriction ◽  
Wall Growth ◽  
In Cells

In common with other cellular machineries, the actomyosin contractile ring that divides cells during cytokinesis does not operate in isolation. Contractile rings in animal cells interact with contiguous actomyosin cortex, while ring constriction in many cell-walled organisms couples tightly to cell wall growth. In fission yeast, a septum grows in the wake of the constricting ring, ensuring cytokinesis leaves two daughter cells fully enclosed by cell wall. Here we mathematical modeled the integrated constriction-septation system in fission yeast, with a kinetic growth model evolving the 3D septum shape coupled to a molecularly explicit simulation of the contractile ring highly constrained by experimental data. Simulations revealed influences in both directions, stabilizing the ring-septum system as a whole. By providing a smooth circular anchoring surface for the ring, the inner septum leading edge stabilized ring organization and tension production; by mechanically regulating septum circularity and in-plane growth, ring tension stabilized septum growth and shape. Genetic or pharmacological perturbation of either subsystem destabilized this delicate balance, precipitating uncontrolled positive feedback with disastrous morphological and functional consequences. Thus, high curvature septum irregularities triggered bridging instabilities, in which contractile ring segments became unanchored. Bridging abolished the local tension-mediated septum shape regulation, exacerbating the irregularity in a mutually destabilizing runaway process. Our model explains a number of previously mysterious experimental observations, including unanchoring of ring segments observed in cells with mutations in the septum-growing β-glucan synthases, and irregular septa in cells with mutations in the contractile ring myosin-II Myo2. Thus, the contractile ring and cell wall growth cellular machineries operate as a single integrated system, whose stability relies on mutual regulation by the two subsystems.

scholarly journals Profilin-mediated Competition between Capping Protein and Formin Cdc12p during Cytokinesis in Fission Yeast

2005 ◽  
Vol 16 (5) ◽  
pp. 2313-2324 ◽  
Author(s):  
David R. Kovar ◽  
Jian-Qiu Wu ◽  
Thomas D. Pollard
Keyword(s):  
Fission Yeast ◽  
Actin Filament ◽  
Actin Filaments ◽  
Cell Separation ◽  
The Other ◽  
Temperature Sensitive ◽  
Contractile Ring ◽  
Capping Protein ◽  
Division Site ◽  
Ring Constriction

Fission yeast capping protein SpCP is a heterodimer of two subunits (Acp1p and Acp2p) that binds actin filament barbed ends. Neither acp1 nor acp2 is required for viability, but cells lacking either or both subunits have cytokinesis defects under stressful conditions, including elevated temperature, osmotic stress, or in combination with numerous mild mutations in genes important for cytokinesis. Defects arise as the contractile ring constricts and disassembles, resulting in delays in cell separation. Genetic and biochemical interactions show that the cytokinesis formin Cdc12p competes with capping protein for actin filament barbed ends in cells. Deletion of acp2 partly suppresses cytokinesis defects in temperature-sensitive cdc12-112 cells and mild overexpression of capping protein kills cdc12-112 cells. Biochemically, profilin has opposite effects on filaments capped with Cdc12p and capping protein. Profilin depolymerizes actin filaments capped by capping protein but allows filaments capped by Cdc12p to grow at their barbed ends. Once associated with a barbed end, either Cdc12p or capping protein prevents the other from influencing polymerization at that end. Given that capping protein arrives at the division site 20 min later than Cdc12p, capping protein may slowly replace Cdc12p on filament barbed ends in preparation for filament disassembly during ring constriction.

scholarly journals Characterization of the roles of Blt1p in fission yeast cytokinesis

2014 ◽  
Vol 25 (13) ◽  
pp. 1946-1957 ◽  
Author(s):  
John W. Goss ◽  
Sunhee Kim ◽  
Hannah Bledsoe ◽  
Thomas D. Pollard
Keyword(s):  
Cell Division ◽  
Fission Yeast ◽  
Cell Separation ◽  
Analytical Ultracentrifugation ◽  
Contractile Ring ◽  
Glucan Synthase ◽  
Temporal Regulation ◽  
Septation Initiation Network ◽  
Ring Constriction

Spatial and temporal regulation of cytokinesis is essential for cell division, yet the mechanisms that control the formation and constriction of the contractile ring are incompletely understood. In the fission yeast Schizosaccharomyces pombe proteins that contribute to the cytokinetic contractile ring accumulate during interphase in nodes—precursor structures around the equatorial cortex. During mitosis, additional proteins join these nodes, which condense to form the contractile ring. The cytokinesis protein Blt1p is unique in being present continuously in nodes from early interphase through to the contractile ring until cell separation. Blt1p was shown to stabilize interphase nodes, but its functions later in mitosis were unclear. We use analytical ultracentrifugation to show that purified Blt1p is a tetramer. We find that Blt1p interacts physically with Sid2p and Mob1p, a protein kinase complex of the septation initiation network, and confirm known interactions with F-BAR protein Cdc15p. Contractile rings assemble normally in blt1∆ cells, but the initiation of ring constriction and completion of cell division are delayed. We find three defects that likely contribute to this delay. Without Blt1p, contractile rings recruited and retained less Sid2p/Mob1p and Clp1p phosphatase, and β-glucan synthase Bgs1p accumulated slowly at the cleavage site.

scholarly journals Contractile Ring Constriction and Cell Wall Growth are Regulated by Mechanical Feedback and Destabilized by Mutations in Fission Yeast

2020 ◽  
Vol 118 (3) ◽  
pp. 440a
Author(s):  
Sathish Thiyagarajan ◽  
Zachary A. McDargh ◽  
Shuyuan Wang ◽  
Ben O'Shaughnessy
Keyword(s):  
Cell Wall ◽  
Fission Yeast ◽  
Contractile Ring ◽  
Cell Wall Growth ◽  
Ring Constriction ◽  
Wall Growth ◽  
Mechanical Feedback

scholarly journals Roles of Mso1 and the SM protein Sec1 in efficient vesicle fusion during fission yeast cytokinesis

2020 ◽  
Vol 31 (15) ◽  
pp. 1570-1583
Author(s):  
Kenneth S. Gerien ◽  
Sha Zhang ◽  
Alexandra C. Russell ◽  
Yi-Hua Zhu ◽  
Vedud Purde ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Fission Yeast ◽  
Vesicle Fusion ◽  
Contractile Ring ◽  
Division Site ◽  
Ring Constriction ◽  
Sm Protein

Mso1 and the SM protein Sec1 aid in the efficient fusion of vesicles at the division site in fission yeast, which is important for proper contractile-ring constriction and plasma-membrane closure during cytokinesis.

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 Counting actin in contractile rings reveals novel contributions of cofilin and type II myosins to fission yeast cytokinesis

2021 ◽  
Author(s):  
Qian Chen ◽  
Mamata Malla ◽  
Thomas D. Pollard
Keyword(s):  
Fission Yeast ◽  
Actin Filaments ◽  
Yeast Cells ◽  
Type Ii ◽  
Wild Type ◽  
Contractile Ring ◽  
Peak Number ◽  
Ring Constriction ◽  
Proportional Increase ◽  
Mutant Cells

Cytokinesis by animals, fungi and amoebas depends on actomyosin contractile rings, which are stabilized by continuous turnover of actin filaments. Remarkably little is known about the amount of polymerized actin in contractile rings, so we used low concentration of GFP-Lifeact to count total polymerized actin molecules in the contractile rings of live fission yeast cells. Contractile rings of wild-type cells accumulated polymerized actin molecules at 4,900/min to a peak number of ~198,000 followed by a loss of actin at 5,400/min throughout ring constriction. In adf1-M3 mutant cells with cofilin that severs actin filaments poorly, contractile rings accumulated polymerized actin at twice the normal rate and eventually had almost two-fold more actin along with a proportional increase in type II myosins Myo2, Myp2 and formin Cdc12. Although 30% of adf1-M3 mutant cells failed to constrict their rings fully, the rest lost actin from the rings at the wild-type rates. Mutations of type II myosins Myo2 and Myp2 reduced contractile ring actin filaments by half and slowed the rate of actin loss from the rings.

scholarly journals Counting actin in contractile rings reveals novel contributions of cofilin and type II myosins to fission yeast cytokinesis

2021 ◽  
Author(s):  
Mamata Malla ◽  
Thomas D. Pollard ◽  
Qian Chen
Keyword(s):  
Fission Yeast ◽  
Actin Filaments ◽  
Yeast Cells ◽  
Type Ii ◽  
Wild Type ◽  
Contractile Ring ◽  
Peak Number ◽  
Ring Constriction ◽  
Proportional Increase ◽  
Mutant Cells

Cytokinesis by animals, fungi and amoebas depends on actomyosin contractile rings, which are stabilized by continuous turnover of actin filaments. Remarkably little is known about the amount of polymerized actin in contractile rings, so we used low concentration of GFP-Lifeact to count total polymerized actin molecules in the contractile rings of live fission yeast cells. Contractile rings of wild-type cells accumulated polymerized actin molecules at 4,900/min to a peak number of ∼198,000 followed by a loss of actin at 5,400/min throughout ring constriction. In adf1-M3 mutant cells with cofilin that severs actin filaments poorly, contractile rings accumulated polymerized actin at twice the normal rate and eventually had almost two-fold more actin along with a proportional increase in type II myosins Myo2, Myp2 and formin Cdc12. Although 30% of adf1-M3 mutant cells failed to constrict their rings fully, the rest lost actin from the rings at the wild-type rates. Mutations of type II myosins Myo2 and Myp2 reduced contractile ring actin filaments by half and slowed the rate of actin loss from the rings.

scholarly journals Actin filament severing by cofilin is more important for assembly than constriction of the cytokinetic contractile ring

2011 ◽  
Vol 195 (3) ◽  
pp. 485-498 ◽  
Author(s):  
Qian Chen ◽  
Thomas D. Pollard
Keyword(s):  
Fission Yeast ◽  
Computer Simulations ◽  
Actin Filament ◽  
Actin Filaments ◽  
Actin Binding ◽  
Wild Type ◽  
Contractile Ring ◽  
Ring Constriction ◽  
Release Model ◽  
Mutant Cells

We created two new mutants of fission yeast cofilin to investigate why cytokinesis in many organisms depends on this small actin-binding protein. These mutant cofilins bound actin monomers normally, but bound and severed ADP-actin filaments much slower than wild-type cofilin. Cells depending on mutant cofilins condensed nodes, precursors of the contractile ring, into clumps rather than rings. Starting from clumped nodes, mutant cells slowly assembled rings from diverse intermediate structures including spiral strands containing actin filaments and other contractile ring proteins. This process in mutant cells depended on α-actinin. These slowly assembled contractile rings constricted at a normal rate but with more variability, indicating ring constriction is not very sensitive to defects in severing by cofilin. Computer simulations of the search-capture-pull and release model of contractile ring formation predicted that nodes clump when the release step is slow, so cofilin severing of actin filament connections between nodes likely contributes to the release step.

Sign in / Sign up

Export Citation Format

Share Document