scholarly journals Schizosaccharomyces pombe Calmodulin, Cam1, Plays a Crucial Role in Sporulation by Recruiting and Stabilizing the Spindle Pole Body Components Responsible for Assembly of the Forespore Membrane

2010 ◽  
Vol 9 (12) ◽  
pp. 1925-1935 ◽  
Author(s):  
Akiko Itadani ◽  
Taro Nakamura ◽  
Aiko Hirata ◽  
Chikashi Shimoda
Keyword(s):  
Plasma Membrane ◽  
Schizosaccharomyces Pombe ◽  
Crucial Role ◽  
Essential Role ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Membrane Formation ◽  
Content Type ◽  
Pole Body ◽  
Body Components

ABSTRACT Calmodulin in Schizosaccharomyces pombe is encoded by the cam1 + gene, which is indispensable for both vegetative growth and sporulation. Here, we report how Cam1 functions in spore formation. We found that Cam1 preferentially localized to the spindle pole body (SPB) during meiosis and sporulation. Formation of the forespore membrane, a precursor of the plasma membrane in spores, was blocked in a missense cam1 mutant, which was viable but unable to sporulate. Three SPB proteins necessary for the onset of forespore membrane formation, Spo2, Spo13, and Spo15, were unable to localize to the SPB in the cam1 mutant although five core SPB components that were tested were present. Recruitment of Spo2 and Spo13 is known to require the presence of Spo15 in the SPB. Notably, Spo15 was unstable in the cam1 mutant, and as a result, SPB localization of Spo2 and Spo13 was lost. Overexpression of Spo15 partially alleviated the sporulation defect in the cam1 mutant. These results indicate that calmodulin plays an essential role in forespore membrane formation by stably maintaining Spo15, and thus Spo2 and Spo13, at the SPB in meiotic cells.

scholarly journals The Mammalian γ-Tubulin Complex Contains Homologues of the Yeast Spindle Pole Body Components Spc97p and Spc98p

1998 ◽  
Vol 141 (3) ◽  
pp. 663-674 ◽  
Author(s):  
Steven M. Murphy ◽  
Lenore Urbani ◽  
Tim Stearns
Keyword(s):  
Mammalian Cells ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Microtubule Organizing Centers ◽  
Molecular Weights ◽  
Microtubule Polymerization ◽  
Pole Body ◽  
Human Proteins ◽  
Body Components ◽  
Cytoplasmic Complex

γ-Tubulin is a universal component of microtubule organizing centers where it is believed to play an important role in the nucleation of microtubule polymerization. γ-Tubulin also exists as part of a cytoplasmic complex whose size and complexity varies in different organisms. To investigate the composition of the cytoplasmic γ-tubulin complex in mammalian cells, cell lines stably expressing epitope-tagged versions of human γ-tubulin were made. The epitope-tagged γ-tubulins expressed in these cells localize to the centrosome and are incorporated into the cytoplasmic γ-tubulin complex. Immunoprecipitation of this complex identifies at least seven proteins, with calculated molecular weights of 48, 71, 76, 100, 101, 128, and 211 kD. We have identified the 100- and 101-kD components of the γ-tubulin complex as homologues of the yeast spindle pole body proteins Spc97p and Spc98p, and named the corresponding human proteins hGCP2 and hGCP3. Sequence analysis revealed that these proteins are not only related to their respective homologues, but are also related to each other. GCP2 and GCP3 colocalize with γ-tubulin at the centrosome, cosediment with γ-tubulin in sucrose gradients, and coimmunoprecipitate with γ-tubulin, indicating that they are part of the γ-tubulin complex. The conservation of a complex involving γ-tubulin, GCP2, and GCP3 from yeast to mammals suggests that structurally diverse microtubule organizing centers such as the yeast spindle pole body and the animal centrosome share a common molecular mechanism for microtubule nucleation.

Yeast Spindle Pole Body Components

1991 ◽  
Vol 56 (0) ◽  
pp. 687-692 ◽  
Author(s):  
M.P. Rout ◽  
J.V. Kilmartin
Keyword(s):  
Spindle Pole Body ◽  
Spindle Pole ◽  
Pole Body ◽  
Body Components

scholarly journals Vesicle Docking to the Spindle Pole Body Is Necessary to Recruit the Exocyst During Membrane Formation inSaccharomyces cerevisiae

2010 ◽  
Vol 21 (21) ◽  
pp. 3693-3707 ◽  
Author(s):  
Erin M. Mathieson ◽  
Yasuyuki Suda ◽  
Mark Nickas ◽  
Brian Snydsman ◽  
Trisha N. Davis ◽  
...  
Keyword(s):  
De Novo ◽  
Spindle Pole Body ◽  
Coiled Coil ◽  
Resonance Energy ◽  
Initiation Site ◽  
Spindle Pole ◽  
Rab Gtpase ◽  
Membrane Formation ◽  
Vesicle Docking ◽  
Pole Body

During meiosis II in Saccharomyces cerevisiae, the cytoplasmic face of the spindle pole body, referred to as the meiosis II outer plaque (MOP), is modified in both composition and structure to become the initiation site for de novo formation of a membrane called the prospore membrane. The MOP serves as a docking complex for precursor vesicles that are targeted to its surface. Using fluorescence resonance energy transfer analysis, the orientation of coiled-coil proteins within the MOP has been determined. The N-termini of two proteins, Mpc54p and Spo21p, were oriented toward the outer surface of the structure. Mutations in the N-terminus of Mpc54p resulted in a unique phenotype: precursor vesicles loosely tethered to the MOP but did not contact its surface. Thus, these mpc54 mutants separate the steps of vesicle association and docking. Using these mpc54 mutants, we determined that recruitment of the Rab GTPase Sec4p, as well as the exocyst components Sec3p and Sec8p, to the precursor vesicles requires vesicle docking to the MOP. This suggests that the MOP promotes membrane formation both by localization of precursor vesicles to a particular site and by recruitment of a second tethering complex, the exocyst, that stimulates downstream events of fusion.

scholarly journals A stable microtubule array drives fission yeast polarity reestablishment upon quiescence exit

2015 ◽  
Vol 210 (1) ◽  
pp. 99-113 ◽  
Author(s):  
Damien Laporte ◽  
Fabien Courtout ◽  
Benoît Pinson ◽  
Jim Dompierre ◽  
Bénédicte Salin ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Actin Filament ◽  
Molecular Model ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Microtubule Array ◽  
Pole Body

Cells perpetually face the decision to proliferate or to stay quiescent. Here we show that upon quiescence establishment, Schizosaccharomyces pombe cells drastically rearrange both their actin and microtubule (MT) cytoskeletons and lose their polarity. Indeed, while polarity markers are lost from cell extremities, actin patches and cables are reorganized into actin bodies, which are stable actin filament–containing structures. Astonishingly, MTs are also stabilized and rearranged into a novel antiparallel bundle associated with the spindle pole body, named Q-MT bundle. We have identified proteins involved in this process and propose a molecular model for Q-MT bundle formation. Finally and importantly, we reveal that Q-MT bundle elongation is involved in polarity reestablishment upon quiescence exit and thereby the efficient return to the proliferative state. Our work demonstrates that quiescent S. pombe cells assemble specific cytoskeleton structures that improve the swiftness of the transition back to proliferation.

S. pombe sporulation-specific coiled-coil protein Spo15p is localized to the spindle pole body and essential for its modification

2000 ◽  
Vol 113 (3) ◽  
pp. 545-554 ◽  
Author(s):  
S. Ikemoto ◽  
T. Nakamura ◽  
M. Kubo ◽  
C. Shimoda
Keyword(s):  
Life Cycle ◽  
Fusion Gene ◽  
Spindle Pole Body ◽  
Coiled Coil ◽  
Spindle Pole ◽  
Wild Type ◽  
Membrane Formation ◽  
Pole Body ◽  
Spindle Pole Bodies ◽  
Meiotic Spindles

Spindle pole bodies in the fission yeast Schizosaccharomyces pombe are required during meiosis, not only for spindle formation but also for the assembly of forespore membranes. The spo15 mutant is defective in the formation of forespore membranes, which develop into spore envelopes. The spo15(+)gene encodes a protein with a predicted molecular mass of 223 kDa, containing potential coiled-coil regions. The spo15 gene disruptant was not lethal, but was defective in spore formation. Northern and western analyses indicated that spo15(+) was expressed not only in meiotic cells but also in vegetative cells. When the spo15-GFP fusion gene was expressed by the authentic spo15 promoter during vegetative growth and sporulation, the fusion protein colocalized with Sad1p, which is a component of spindle pole bodies. Meiotic divisions proceeded in spo15delta cells with kinetics similar to those in wild-type cells. In addition, the morphology of the mitotic and meiotic spindles and the nuclear segregation were normal in spo15delta. Intriguingly, transformation of spindle pole bodies from a punctate to a crescent form prior to forespore membrane formation was not observed in spo15delta cells. We conclude that Spo15p is associated with spindle pole bodies throughout the life cycle and plays an indispensable role in the initiation of spore membrane formation.

scholarly journals The exocytic Rabs Ypt3 and Ypt2 regulate the early step of biogenesis of the spore plasma membrane in fission yeast

2016 ◽  
Vol 27 (21) ◽  
pp. 3317-3328 ◽  
Author(s):  
Kazuki Imada ◽  
Taro Nakamura
Keyword(s):  
Plasma Membrane ◽  
Fission Yeast ◽  
Membrane Vesicle ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Small Gtpase ◽  
Rab Protein ◽  
Pole Body ◽  
Membrane Compartment ◽  
Exocytic Pathway

During fission yeast sporulation, a membrane compartment called the forespore membrane (FSM) is newly formed on the spindle pole body (SPB). The FSM expands by membrane vesicle fusion, encapsulates the daughter nucleus resulting from meiosis, and eventually matures into the plasma membrane of the spore. Although many of the genes involved in FSM formation have been identified, its molecular mechanism is not fully understood. Here a genetic screen for sporulation-deficient mutations identified Ypt3, a Rab-family small GTPase known to function in the exocytic pathway. The ypt3-ki8 mutant showed defects in both the initiation of FSM biogenesis and FSM expansion. We also show that a mutation in Ypt2, another Rab protein that may function in the same pathway as Ypt3, compromises the initiation of FSM formation. As meiosis proceeds, both GFP-Ypt3 and GFP-Ypt2 are observed at the SPB and then relocalize to the FSM. Their localizations at the SPB precede FSM formation and depend on the meiotic SPB component Spo13, a putative GDP/GTP exchange factor for Ypt2. Given that Spo13 is essential for initiating FSM formation, these results suggest that two exocytic Rabs, Ypt3 and Ypt2, regulate the initiation of FSM formation on the SPB in concert with Spo13.

scholarly journals Cosegregation of asymmetric features during cell division

Open Biology ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 210116
Author(s):  
Silje Anda ◽  
Erik Boye ◽  
Kay Oliver Schink ◽  
Beata Grallert
Keyword(s):  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Unicellular Eukaryote ◽  
Unicellular Eukaryotes ◽  
Pole Body ◽  
Cellular Asymmetry ◽  
Multicellular Organisms ◽  
Chromosome I

Cellular asymmetry plays a major role in the ageing and evolution of multicellular organisms. However, it remains unknown how the cell distinguishes ‘old’ from ‘new’ and whether asymmetry is an attribute of highly specialized cells or a feature inherent in all cells. Here, we investigate the segregation of three asymmetric features: old and new DNA, the spindle pole body (SPB, the centrosome analogue) and the old and new cell ends, using a simple unicellular eukaryote, Schizosaccharomyces pombe . To our knowledge, this is the first study exploring three asymmetric features in the same cells. We show that of the three chromosomes of S. pombe , chromosome I containing the new parental strand, preferentially segregated to the cells inheriting the old cell end. Furthermore, the new SPB also preferentially segregated to the cells inheriting the old end. Our results suggest that the ability to distinguish ‘old’ from ‘new’ and to segregate DNA asymmetrically are inherent features even in simple unicellular eukaryotes.

scholarly journals Spindle pole body components are reorganized during fission yeast meiosis

2012 ◽  
Vol 23 (10) ◽  
pp. 1799-1811 ◽  
Author(s):  
Midori Ohta ◽  
Masamitsu Sato ◽  
Masayuki Yamamoto
Keyword(s):  
Fission Yeast ◽  
Meiotic Prophase ◽  
Spindle Pole Body ◽  
Mitotic Cell ◽  
Spindle Pole ◽  
Nuclear Movement ◽  
Pole Body ◽  
Proper Number ◽  
Body Components ◽  
Yeast Meiosis

During meiosis, the centrosome/spindle pole body (SPB) must be regulated in a manner distinct from that of mitosis to achieve a specialized cell division that will produce gametes. In this paper, we demonstrate that several SPB components are localized to SPBs in a meiosis-specific manner in the fission yeast Schizosaccharomyces pombe. SPB components, such as Cut12, Pcp1, and Spo15, which stay on the SPB during the mitotic cell cycle, disassociate from the SPB during meiotic prophase and then return to the SPB immediately before the onset of meiosis I. Interestingly, the polo kinase Plo1, which normally localizes to the SPB during mitosis, is excluded from them in meiotic prophase, when meiosis-specific, horse-tail nuclear movement occurs. We found that exclusion of Plo1 during this period was essential to properly remodel SPBs, because artificial targeting of Plo1 to SPBs resulted in an overduplication of SPBs. We also found that the centrin Cdc31 was required for meiotic SPB remodeling. Thus Plo1 and a centrin play central roles in the meiotic SPB remodeling, which is essential for generating the proper number of meiotic SPBs and, thereby provide unique characteristics to meiotic divisions.

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