scholarly journals Ctf3/CENP-I provides a docking site for the desumoylase Ulp2 at the kinetochore

2021 ◽  
Vol 220 (8) ◽  
Author(s):  
Yun Quan ◽  
Stephen M. Hinshaw ◽  
Pang-Che Wang ◽  
Stephen C. Harrison ◽  
Huilin Zhou
Keyword(s):  
Cell Cycle ◽  
Binding Site ◽  
Chromosome Segregation ◽  
Docking Site ◽  
Centromeric Dna ◽  
Kinetochore Protein ◽  
Step Process ◽  
Daughter Cells ◽  
Sister Chromatids ◽  
Spindle Microtubules

The step-by-step process of chromosome segregation defines the stages of the cell cycle. In eukaryotes, signals controlling these steps converge upon the kinetochore, a multiprotein assembly that connects spindle microtubules to chromosomal centromeres. Kinetochores control and adapt to major chromosomal transactions, including replication of centromeric DNA, biorientation of sister centromeres on the metaphase spindle, and transit of sister chromatids into daughter cells during anaphase. Although the mechanisms that ensure tight microtubule coupling at anaphase are at least partly understood, kinetochore adaptations that support other cell cycle transitions are not. We report here a mechanism that enables regulated control of kinetochore sumoylation. A conserved surface of the Ctf3/CENP-I kinetochore protein provides a binding site for Ulp2, the nuclear enzyme that removes SUMO chains from modified substrates. Ctf3 mutations that disable Ulp2 recruitment cause elevated inner kinetochore sumoylation and defective chromosome segregation. The location of the site within the assembled kinetochore suggests coordination between sumoylation and other cell cycle–regulated processes.

scholarly journals The structural basis for Ulp2 recruitment to the kinetochore

2021 ◽  
Author(s):  
Yun Quan ◽  
Stephen M. Hinshaw ◽  
Pang-Che Wang ◽  
Stephen C. Harrison ◽  
Huilin Zhou
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Structural Basis ◽  
Centromeric Dna ◽  
Step Process ◽  
Sumo Protease ◽  
Daughter Cells ◽  
Sister Chromatids ◽  
Spindle Microtubules

ABSTRACTThe step-by-step process of chromosome segregation defines the stages of the cell division cycle. In eukaryotes, signaling pathways that control these steps converge upon the kinetochore, a multiprotein assembly that connects spindle microtubules to the centromere of each chromosome. Kinetochores control and adapt to major chromosomal transactions, including replication of centromeric DNA, biorientation of sister centromeres on the metaphase spindle, and transit of sister chromatids into daughter cells during anaphase. Although the mechanisms that ensure tight microtubule coupling at anaphase are at least partly understood, kinetochore adaptations that support other cell cycle transitions are not. We report here a mechanism that enables regulated control of kinetochore sumoylation. A conserved surface of the Ctf3/CENP-I kinetochore protein provides a binding site for the SUMO protease, Ulp2. Ctf3 mutations that disable Ulp2 recruitment cause elevated inner kinetochore sumoylation and defective chromosome segregation. The location of the site within the assembled kinetochore suggests coordination between sumoylation and other cell cycle-regulated processes.

scholarly journals The structural basis for kinetochore stabilization by Cnn1/CENP-T

2020 ◽  
Author(s):  
Stephen M. Hinshaw ◽  
Stephen C. Harrison
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Live Cell Imaging ◽  
Feedback Regulation ◽  
Structural Basis ◽  
Daughter Cells ◽  
Sister Chromatids ◽  
High Resolution Structure ◽  
Spindle Microtubules ◽  
Resolution Structure

ABSTRACTChromosome segregation depends on a regulated connection between spindle microtubules and centromeric DNA. The kinetochore, a massive modular protein assembly, mediates this connection and also serves as a signaling hub that integrates and responds to changing cues during the cell cycle. Kinetochore functions evolve as the cell cycle progresses, culminating in the assurance of a persistent chromosome-microtubule connection during anaphase, when sister chromatids must transit into daughter cells uninterrupted. We previously determined the structure of the Ctf19 complex, a group of kinetochore proteins at the centromeric base of the kinetochore. We now present a high-resolution structure of a Ctf19 complex sub-assembly involved in centromere-microtubule contact: the Ctf3 complex bound to the Cnn1-Wip1 heterodimer. The resulting composite model of the Ctf19 complex and live-cell imaging experiments provide a mechanism for Cnn1-Wip1 recruitment to the kinetochore. The mechanism suggests feedback regulation of Ctf19 complex assembly and unanticipated similarities in kinetochore organization between yeast and vertebrates.

scholarly journals An assay for de novo kinetochore assembly reveals a key role for the CENP-T pathway in budding yeast

2018 ◽  
Author(s):  
Jackie Lang ◽  
Adrienne Barber ◽  
Sue Biggins
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
De Novo ◽  
Budding Yeast ◽  
Centromeric Dna ◽  
Kinetochore Assembly ◽  
Ndc80 Complex ◽  
Spindle Microtubules ◽  
Underlying Mechanisms ◽  
Mitotic Phosphorylation

ABSTRACTChromosome segregation depends on the kinetochore, the machine that establishes force-bearing attachments between DNA and spindle microtubules. Kinetochores are formed every cell cycle via a highly regulated process that requires coordinated assembly of multiple subcomplexes on specialized chromatin. To elucidate the underlying mechanisms, we developed an assay to assemble kinetochores de novo using centromeric DNA and budding yeast extracts. Assembly is enhanced by mitotic phosphorylation of the Dsn1 kinetochore protein and generates kinetochores capable of binding microtubules. We used this assay to investigate why kinetochores recruit the microtubule-binding Ndc80 complex via two receptors: the Mis12 complex and CENP-T. Although the CENP-T pathway is non-essential in yeast, we demonstrate that it becomes essential for viability and Ndc80c recruitment when the Mis12 pathway is crippled by defects in Dsn1 phosphorylation. Assembling kinetochores de novo in yeast extracts provides a powerful and genetically tractable method to elucidate critical regulatory events in the future.

scholarly journals An assay for de novo kinetochore assembly reveals a key role for the CENP-T pathway in budding yeast

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Jackie Lang ◽  
Adrienne Barber ◽  
Sue Biggins
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
De Novo ◽  
Budding Yeast ◽  
Centromeric Dna ◽  
Kinetochore Assembly ◽  
Ndc80 Complex ◽  
Spindle Microtubules ◽  
Underlying Mechanisms ◽  
Mitotic Phosphorylation

Chromosome segregation depends on the kinetochore, the machine that establishes force-bearing attachments between DNA and spindle microtubules. Kinetochores are formed every cell cycle via a highly regulated process that requires coordinated assembly of multiple subcomplexes on specialized chromatin. To elucidate the underlying mechanisms, we developed an assay to assemble kinetochores de novo using centromeric DNA and budding yeast extracts. Assembly is enhanced by mitotic phosphorylation of the Dsn1 kinetochore protein and generates kinetochores capable of binding microtubules. We used this assay to investigate why kinetochores recruit the microtubule-binding Ndc80 complex via two receptors: the Mis12 complex and CENP-T. Although the CENP-T pathway is non-essential in yeast, we demonstrate that it becomes essential for viability and Ndc80c recruitment when the Mis12 pathway is crippled by defects in Dsn1 phosphorylation. Assembling kinetochores de novo in yeast extracts provides a powerful and genetically tractable method to elucidate critical regulatory events in the future.

scholarly journals The spindle checkpoint protein Mad2 regulates APC/C activity during prometaphase and metaphase of meiosis I in Saccharomyces cerevisiae

2011 ◽  
Vol 22 (16) ◽  
pp. 2848-2861 ◽  
Author(s):  
Dai Tsuchiya ◽  
Claire Gonzalez ◽  
Soni Lacefield
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Chromosome Segregation ◽  
Meiotic Division ◽  
Spindle Checkpoint ◽  
Yeast Cells ◽  
Meiotic Cell ◽  
Checkpoint Protein ◽  
Sister Chromatids ◽  
Meiosis I

In many eukaryotes, disruption of the spindle checkpoint protein Mad2 results in an increase in meiosis I nondisjunction, suggesting that Mad2 has a conserved role in ensuring faithful chromosome segregation in meiosis. To characterize the meiotic function of Mad2, we analyzed individual budding yeast cells undergoing meiosis. We find that Mad2 sets the duration of meiosis I by regulating the activity of APCCdc20. In the absence of Mad2, most cells undergo both meiotic divisions, but securin, a substrate of the APC/C, is degraded prematurely, and prometaphase I/metaphase I is accelerated. Some mad2Δ cells have a misregulation of meiotic cell cycle events and undergo a single aberrant division in which sister chromatids separate. In these cells, both APCCdc20 and APCAma1 are prematurely active, and meiosis I and meiosis II events occur in a single meiotic division. We show that Mad2 indirectly regulates APCAma1 activity by decreasing APCCdc20 activity. We propose that Mad2 is an important meiotic cell cycle regulator that ensures the timely degradation of APC/C substrates and the proper orchestration of the meiotic divisions.

Epigenetic dynamics across the cell cycle

2010 ◽  
Vol 48 ◽  
pp. 107-120 ◽  
Author(s):  
Tony Bou Kheir ◽  
Anders H. Lund
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Cell Cycle Progression ◽  
Current Knowledge ◽  
Chromatin Condensation ◽  
Chromatin Modifications ◽  
Cycle Progression ◽  
Daughter Cells ◽  
Mammalian Cell Cycle ◽  
Regulate Cell Cycle Progression

Progression of the mammalian cell cycle depends on correct timing and co-ordination of a series of events, which are managed by the cellular transcriptional machinery and epigenetic mechanisms governing genome accessibility. Epigenetic chromatin modifications are dynamic across the cell cycle, and are shown to influence and be influenced by cell-cycle progression. Chromatin modifiers regulate cell-cycle progression locally by controlling the expression of individual genes and globally by controlling chromatin condensation and chromosome segregation. The cell cycle, on the other hand, ensures a correct inheritance of epigenetic chromatin modifications to daughter cells. In this chapter, we summarize the current knowledge on the dynamics of epigenetic chromatin modifications during progression of the cell cycle.

scholarly journals Anaphase Bridges: Not All Natural Fibers Are Healthy

Genes ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 902
Author(s):  
Alice Finardi ◽  
Lucia F. Massari ◽  
Rosella Visintin
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Potential Role ◽  
Genome Instability ◽  
Natural Fibers ◽  
S Phase ◽  
Dna Lesions ◽  
Anaphase Bridges ◽  
Daughter Cells ◽  
Sister Chromatids

At each round of cell division, the DNA must be correctly duplicated and distributed between the two daughter cells to maintain genome identity. In order to achieve proper chromosome replication and segregation, sister chromatids must be recognized as such and kept together until their separation. This process of cohesion is mainly achieved through proteinaceous linkages of cohesin complexes, which are loaded on the sister chromatids as they are generated during S phase. Cohesion between sister chromatids must be fully removed at anaphase to allow chromosome segregation. Other (non-proteinaceous) sources of cohesion between sister chromatids consist of DNA linkages or sister chromatid intertwines. DNA linkages are a natural consequence of DNA replication, but must be timely resolved before chromosome segregation to avoid the arising of DNA lesions and genome instability, a hallmark of cancer development. As complete resolution of sister chromatid intertwines only occurs during chromosome segregation, it is not clear whether DNA linkages that persist in mitosis are simply an unwanted leftover or whether they have a functional role. In this review, we provide an overview of DNA linkages between sister chromatids, from their origin to their resolution, and we discuss the consequences of a failure in their detection and processing and speculate on their potential role.

scholarly journals Pds5 regulators segregate cohesion and condensation pathways in Saccharomyces cerevisiae

2015 ◽  
Vol 112 (22) ◽  
pp. 7021-7026 ◽  
Author(s):  
Kevin Tong ◽  
Robert V. Skibbens
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Temperature Sensitivity ◽  
Mutant Cell ◽  
Important Advance ◽  
Daughter Cells ◽  
Sister Chromatids ◽  
Discrete Structures ◽  
Cell Condensation ◽  
Mutant Cells

Cohesins are required both for the tethering together of sister chromatids (termed cohesion) and subsequent condensation into discrete structures—processes fundamental for faithful chromosome segregation into daughter cells. Differentiating between cohesin roles in cohesion and condensation would provide an important advance in studying chromatin metabolism. Pds5 is a cohesin-associated factor that is essential for both cohesion maintenance and condensation. Recent studies revealed that ELG1 deletion suppresses the temperature sensitivity of pds5 mutant cells. However, the mechanisms through which Elg1 may regulate cohesion and condensation remain unknown. Here, we report that ELG1 deletion from pds5-1 mutant cells results in a significant rescue of cohesion, but not condensation, defects. Based on evidence that Elg1 unloads the DNA replication clamp PCNA from DNA, we tested whether PCNA overexpression would similarly rescue pds5-1 mutant cell cohesion defects. The results indeed reveal that elevated levels of PCNA rescue pds5-1 temperature sensitivity and cohesion defects, but do not rescue pds5-1 mutant cell condensation defects. In contrast, RAD61 deletion rescues the condensation defect, but importantly, neither the temperature sensitivity nor cohesion defects exhibited by pds5-1 mutant cells. In combination, these findings reveal that cohesion and condensation are separable pathways and regulated in nonredundant mechanisms. These results are discussed in terms of a new model through which cohesion and condensation are spatially regulated.

scholarly journals Aurora B Kinase Exists in a Complex with Survivin and INCENP and Its Kinase Activity Is Stimulated by Survivin Binding and Phosphorylation

2002 ◽  
Vol 13 (9) ◽  
pp. 3064-3077 ◽  
Author(s):  
Margaret A. Bolton ◽  
Weijie Lan ◽  
Shannon E. Powers ◽  
Mark L. McCleland ◽  
Jian Kuang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Kinase Activity ◽  
Genetic Interactions ◽  
Aurora B ◽  
Hydrodynamic Properties ◽  
Aurora B Kinase ◽  
Survivin Gene ◽  
Spindle Microtubules ◽  
Cycle Dependent

Aurora B regulates chromosome segregation and cytokinesis and is the first protein to be implicated as a regulator of bipolar attachment of spindle microtubules to kinetochores. Evidence from several systems suggests that Aurora B is physically associated with inner centromere protein (INCENP) in mitosis and has genetic interactions with Survivin. It is unclear whether the Aurora B and INCENP interaction is cell cycle regulated and if Survivin physically interacts in this complex. In this study, we cloned theXenopus Survivin gene, examined its association with Aurora B and INCENP, and determined the effect of its binding on Aurora B kinase activity. We demonstrate that in the Xenopusearly embryo, all of the detectable Survivin is in a complex with both Aurora B and INCENP throughout the cell cycle. Survivin and Aurora B bind different domains on INCENP. Aurora B activity is stimulated >10-fold in mitotic extracts; this activation is phosphatase sensitive, and the binding of Survivin is required for full Aurora B activity. We also find the hydrodynamic properties of the Aurora B/Survivin/INCENP complex are cell cycle regulated. Our data indicate that Aurora B kinase activity is regulated by both Survivin binding and cell cycle-dependent phosphorylation.

scholarly journals Kre28-Spc105 interaction is essential for their recruitment at the kinetochore

2021 ◽  
Author(s):  
Babhrubahan Roy ◽  
Janice Sim ◽  
Simon J. Y. Han ◽  
Ajit P. Joglekar
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
High Fidelity ◽  
Protein Assemblies ◽  
Sister Chromatids ◽  
Exact Function ◽  
Interaction Interface ◽  
Macromolecular Protein ◽  
Spindle Microtubules ◽  
Turn Over

Kinetochores are macromolecular protein assemblies that attach sister chromatids to spindle microtubules and mediate accurate chromosome segregation during mitosis. The outer kinetochore consists of the KMN network, a protein super complex made of Knl1 (yeast Spc105), Mis12 (yeast Mtw1) and Ndc80 (yeast Ndc80), which harbors sites for microtubule binding. Within the KMN network, Spc105 acts as interaction hub of components involved in spindle assembly checkpoint (SAC) signaling. It is known that Spc105 forms a complex with kinetochore component Kre28. However, where Kre28 physically localizes in the budding yeast kinetochore is not clear. The exact function of Kre28 at the kinetochore is also unknown. Here, we reveal how Spc105 and Kre28 interact and how they are organized within bioriented yeast kinetochores using genetics and cell biological experiments. We also identify the interaction interface between the two proteins and show that this interaction is important for Spc105 protein turn-over and essential for their mutual recruitment at the kinetochores. We created several truncation mutants of kre28 that do not localize at the kinetochores and so cannot mediate Spc105 loading at the kinetochores. When we over-expressed these mutants, they could sustain the cell viability even though failed to facilitate proper SAC activation and/or error correction. Thus, we inferred that Kre28 indirectly contributes to chromosome biorientation and high-fidelity segregation by regulating Spc105 localization at the kinetochores.

Sign in / Sign up

Export Citation Format

Share Document