scholarly journals The Spindle Pole Body Protein Cdc11p Links Sid4p to the Fission Yeast Septation Initiation Network

2002 ◽  
Vol 13 (4) ◽  
pp. 1203-1214 ◽  
Author(s):  
Gregory C. Tomlin ◽  
Jennifer L. Morrell ◽  
Kathleen L. Gould
Keyword(s):  
Spindle Pole Body ◽  
Direct Interaction ◽  
Spindle Pole ◽  
Small Gtpase ◽  
Dependent Manner ◽  
Body Protein ◽  
Pole Body ◽  
C Terminus ◽  
N Terminus ◽  
Septation Initiation Network

The Schizosaccharomyces pombe septation initiation network (SIN) signals the onset of cell division from the spindle pole body (SPB) and is regulated by the small GTPase Spg1p. The localization of SIN components including Spg1p to the SPB is required for cytokinesis and is dependent on Sid4p, a constitutive resident of SPBs. However, a direct interaction between Sid4p and other members of the SIN has not been detected. To understand how Sid4p is linked to other SIN components, we have begun to characterize an S. pombe homolog of the Saccharomyces cerevisiaeSPB protein Nud1p. We have determined that this S. pombeNud1p homolog corresponds to Cdc11p, a previously uncharacterized SIN element. We report that Cdc11p is present constitutively at SPBs and that its function appears to be required for the localization of all other SIN components to SPBs with the exception of Sid4p. The Cdc11p C terminus localizes the protein to SPBs in a Sid4p-dependent manner, and we demonstrate a direct Cdc11p-Sid4p interaction. The N-terminus of Cdc11p is required for Spg1p binding to SPBs. Our studies indicate that Cdc11p provides a physical link between Sid4p and the Spg1p signaling pathway.

scholarly journals Cnm67p Is a Spacer Protein of theSaccharomyces cerevisiaeSpindle Pole Body Outer Plaque

2001 ◽  
Vol 12 (8) ◽  
pp. 2519-2533 ◽  
Author(s):  
Florian Schaerer ◽  
Garry Morgan ◽  
Mark Winey ◽  
Peter Philippsen
Keyword(s):  
Spindle Pole Body ◽  
Coiled Coil ◽  
Nuclear Migration ◽  
Spindle Pole ◽  
Thin Sections ◽  
Pole Body ◽  
C Terminus ◽  
Functional Homolog ◽  
N Terminus ◽  
Terminal Domains

In Saccharomyces cerevisiae, the spindle pole body (SPB) is the functional homolog of the mammalian centrosome, responsible for the organization of the tubulin cytoskeleton. Cytoplasmic (astral) microtubules essential for the proper segregation of the nucleus into the daughter cell are attached at the outer plaque on the SPB cytoplasmic face. Previously, it has been shown that Cnm67p is an integral component of this structure; cells deleted forCNM67 are lacking the SPB outer plaque and thus experience severe nuclear migration defects. With the use of partial deletion mutants of CNM67, we show that the N- and C-terminal domains of the protein are important for nuclear migration. The C terminus, not the N terminus, is essential for Cnm67p localization to the SPB. On the other hand, only the N terminus is subject to protein phosphorylation of a yet unknown function. Electron microscopy of SPB serial thin sections reveals that deletion of the N- or C-terminal domains disturbs outer plaque formation, whereas mutations in the central coiled-coil domain of Cnm67p change the distance between the SPB core and the outer plaque. We conclude that Cnm67p is the protein that connects the outer plaque to the central plaque embedded in the nuclear envelope, adjusting the space between them by the length of its coiled-coil.

scholarly journals Cdk1 promotes cytokinesis in fission yeast through activation of the septation initiation network

2014 ◽  
Vol 25 (15) ◽  
pp. 2250-2259 ◽  
Author(s):  
Nicole Rachfall ◽  
Alyssa E. Johnson ◽  
Sapna Mehta ◽  
Jun-Song Chen ◽  
Kathleen L. Gould
Keyword(s):  
Cell Cycle ◽  
Spindle Pole Body ◽  
Complete Removal ◽  
Spindle Pole ◽  
Cyclin Dependent Kinase ◽  
Gtpase Activating Protein ◽  
Pole Body ◽  
Kinase Cascade ◽  
Septation Initiation Network ◽  
Cycle Dependent

In Schizosaccharomyces pombe, late mitotic events are coordinated with cytokinesis by the septation initiation network (SIN), an essential spindle pole body (SPB)–associated kinase cascade, which controls the formation, maintenance, and constriction of the cytokinetic ring. It is not fully understood how SIN initiation is temporally regulated, but it depends on the activation of the GTPase Spg1, which is inhibited during interphase by the essential bipartite GTPase-activating protein Byr4-Cdc16. Cells are particularly sensitive to the modulation of Byr4, which undergoes cell cycle–dependent phosphorylation presumed to regulate its function. Polo-like kinase, which promotes SIN activation, is partially responsible for Byr4 phosphorylation. Here we show that Byr4 is also controlled by cyclin-dependent kinase (Cdk1)–mediated phosphorylation. A Cdk1 nonphosphorylatable Byr4 phosphomutant displays severe cell division defects, including the formation of elongated, multinucleate cells, failure to maintain the cytokinetic ring, and compromised SPB association of the SIN kinase Cdc7. Our analyses show that Cdk1-mediated phosphoregulation of Byr4 facilitates complete removal of Byr4 from metaphase SPBs in concert with Plo1, revealing an unexpected role for Cdk1 in promoting cytokinesis through activation of the SIN pathway.

scholarly journals The Sad1-UNC-84 homology domain in Mps3 interacts with Mps2 to connect the spindle pole body with the nuclear envelope

2006 ◽  
Vol 174 (5) ◽  
pp. 665-675 ◽  
Author(s):  
Sue L. Jaspersen ◽  
Adriana E. Martin ◽  
Galina Glazko ◽  
Thomas H. Giddings ◽  
Garry Morgan ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Integral Membrane Proteins ◽  
Microtubule Nucleation ◽  
The Core ◽  
Pole Body ◽  
C Terminus ◽  
Bridge Structures ◽  
Sun Domain

The spindle pole body (SPB) is the sole site of microtubule nucleation in Saccharomyces cerevisiae; yet, details of its assembly are poorly understood. Integral membrane proteins including Mps2 anchor the soluble core SPB in the nuclear envelope. Adjacent to the core SPB is a membrane-associated SPB substructure known as the half-bridge, where SPB duplication and microtubule nucleation during G1 occurs. We found that the half-bridge component Mps3 is the budding yeast member of the SUN protein family (Sad1-UNC-84 homology) and provide evidence that it interacts with the Mps2 C terminus to tether the half-bridge to the core SPB. Mutants in the Mps3 SUN domain or Mps2 C terminus have SPB duplication and karyogamy defects that are consistent with the aberrant half-bridge structures we observe cytologically. The interaction between the Mps3 SUN domain and Mps2 C terminus is the first biochemical link known to connect the half-bridge with the core SPB. Association with Mps3 also defines a novel function for Mps2 during SPB duplication.

scholarly journals N-terminal regions of Mps1 kinase determine functional bifurcation

2010 ◽  
Vol 189 (1) ◽  
pp. 41-56 ◽  
Author(s):  
Yasuhiro Araki ◽  
Linda Gombos ◽  
Suellen P.S. Migueleti ◽  
Lavanya Sivashanmugam ◽  
Claude Antony ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Chemical Biology ◽  
Molecular Level ◽  
Budding Yeast ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Deletion Analysis ◽  
Checkpoint Activation ◽  
Pole Body ◽  
N Terminus

Mps1 is a conserved kinase that in budding yeast functions in duplication of the spindle pole body (SPB), spindle checkpoint activation, and kinetochore biorientation. The identity of Mps1 targets and the subdomains that convey specificity remain largely unexplored. Using a novel combination of systematic deletion analysis and chemical biology, we identified two regions within the N terminus of Mps1 that are essential for either SPB duplication or kinetochore biorientation. Suppression analysis of the MPS1 mutants defective in SPB duplication and biochemical enrichment of Mps1 identified the essential SPB components Spc29 and the yeast centrin Cdc31 as Mps1 targets in SPB duplication. Our data suggest that phosphorylation of Spc29 by Mps1 in G1/S recruits the Mps2–Bbp1 complex to the newly formed SPB to facilitate its insertion into the nuclear envelope. Mps1 phosphorylation of Cdc31 at the conserved T110 residue controls substrate binding to Kar1 protein. These findings explain the multiple SPB duplication defects of mps1 mutants on a molecular level.

scholarly journals S. pombe cdc11p, together with sid4p, provides an anchor for septation initiation network proteins on the spindle pole body

2001 ◽  
Vol 11 (20) ◽  
pp. 1559-1568 ◽  
Author(s):  
Andrea Krapp ◽  
Susanne Schmidt ◽  
Elena Cano ◽  
Viesturs Simanis
Keyword(s):  
Spindle Pole Body ◽  
Spindle Pole ◽  
Pole Body ◽  
Septation Initiation Network

scholarly journals Cut1/separase C-terminus affects spindle pole body positioning in interphase of fission yeast: pointed nuclear formation

2002 ◽  
Vol 7 (11) ◽  
pp. 1113-1124 ◽  
Author(s):  
Takahiro Nakamura ◽  
Koji Nagao ◽  
Yukinobu Nakaseko ◽  
Mitsuhiro Yanagida
Keyword(s):  
Fission Yeast ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Pole Body ◽  
C Terminus ◽  
Body Positioning

scholarly journals Relief of the Dma1-mediated checkpoint requires Dma1 autoubiquitination and dynamic localization

2018 ◽  
Vol 29 (18) ◽  
pp. 2176-2189 ◽  
Author(s):  
Christine M. Jones ◽  
Jun-Song Chen ◽  
Alyssa E. Johnson ◽  
Zachary C. Elmore ◽  
Sierra N. Cullati ◽  
...  
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Ubiquitin Ligase ◽  
Spindle Pole Body ◽  
Mitotic Checkpoint ◽  
Spindle Pole ◽  
Checkpoint Activation ◽  
Pole Body ◽  
Septation Initiation Network ◽  
Anaphase B

Chromosome segregation and cell division are coupled to prevent aneuploidy and cell death. In the fission yeast Schizosaccharomyces pombe, the septation initiation network (SIN) promotes cytokinesis, but upon mitotic checkpoint activation, the SIN is actively inhibited to prevent cytokinesis from occurring before chromosomes have safely segregated. SIN inhibition during the mitotic checkpoint is mediated by the E3 ubiquitin ligase Dma1. Dma1 binds to the CK1-phosphorylated SIN scaffold protein Sid4 at the spindle pole body (SPB), and ubiquitinates it. Sid4 ubiquitination antagonizes the SPB localization of the Pololike kinase Plo1, the major SIN activator, so that SIN signaling is delayed. How this checkpoint is silenced once spindle defects are resolved has not been clear. Here we establish that Dma1 transiently leaves SPBs during anaphase B due to extensive autoubiquitination. The SIN is required for Dma1 to return to SPBs later in anaphase. Blocking Dma1 removal from SPBs by permanently tethering it to Sid4 prevents SIN activation and cytokinesis. Therefore, controlling Dma1’s SPB dynamics in anaphase is an essential step in S. pombe cell division and the silencing of the Dma1-dependent mitotic checkpoint.

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.

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