scholarly journals A novel mechanism for the establishment of sister chromatid cohesion by the ECO1 acetyltransferase

2015 ◽  
Vol 26 (1) ◽  
pp. 117-133 ◽  
Author(s):  
Vincent Guacci ◽  
Jeremiah Stricklin ◽  
Michelle S. Bloom ◽  
Xuánzōng Guō ◽  
Meghna Bhatter ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Current Model ◽  
S Phase ◽  
High Fidelity ◽  
In Vivo Assays ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Cohesin Subunit ◽  
Mutant Cells

Cohesin complex mediates cohesion between sister chromatids, which promotes high-fidelity chromosome segregation. Eco1p acetylates the cohesin subunit Smc3p during S phase to establish cohesion. The current model posits that this Eco1p-mediated acetylation promotes establishment by abrogating the ability of Wpl1p to destabilize cohesin binding to chromosomes. Here we present data from budding yeast that is incompatible with this Wpl1p-centric model. Two independent in vivo assays show that a wpl1∆ fails to suppress cohesion defects of eco1∆ cells. Moreover, a wpl1∆ also fails to suppress cohesion defects engendered by blocking just the essential Eco1p acetylation sites on Smc3p (K112, K113). Thus removing WPL1 inhibition is insufficient for generating cohesion without ECO1 activity. To elucidate how ECO1 promotes cohesion, we conducted a genetic screen and identified a cohesion activator mutation in the SMC3 head domain (D1189H). Smc3-D1189H partially restores cohesion in eco1∆ wpl1∆ or eco1 mutant cells but robustly restores cohesion in cells blocked for Smc3p K112 K113 acetylation. These data support two important conclusions. First, acetylation of the K112 K113 region by Eco1p promotes cohesion establishment by altering Smc3p head function independent of its ability to antagonize Wpl1p. Second, Eco1p targets other than Smc3p K112 K113 are necessary for efficient establishment.

scholarly journals Scc2-mediated loading of cohesin onto chromosomes in G1 yeast cells is insufficient to build cohesion during S phase

2017 ◽  
Author(s):  
Kim A Nasmyth
Keyword(s):  
Replication Fork ◽  
De Novo ◽  
S Phase ◽  
Yeast Cells ◽  
G1 Phase ◽  
Cohesin Complex ◽  
Previous Conclusion ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Cohesin Subunit

SummarySister chromatids are held together from their replication until mitosis. Sister chromatid cohesion is mediated by the ring-shaped cohesin complex and it is thought that cohesin holds sister chromatids together by entrapping sister DNAs within the cohesin ring (Haering et al., 2008). However, how this occurs is not well understood. Because cohesin binds to DNA prior to replication it is possible that the replication fork passes through the lumen of the ring thereby placing replicated sisters inside cohesin rings. If this is the case, loading of cohesin in the G1 phase may be sufficient to build cohesion.We show here that Scc2, a cohesin subunit required for loading cohesin onto chromosomes de novo, is necessary for establishment of cohesion even after Scc2-mediated loading has already taken place during late G1 or early S phase. Our results challenge a previous conclusion based on related experiments whereby Scc2 was found not to be required for cohesion establishment during S phase (Lengronne et al., 2006).

scholarly journals Dosage-Sensitive Regulation of Cohesin Chromosome Binding and Dynamics by Nipped-B, Pds5, and Wapl

2010 ◽  
Vol 30 (20) ◽  
pp. 4940-4951 ◽  
Author(s):  
Maria Gause ◽  
Ziva Misulovin ◽  
Amy Bilyeu ◽  
Dale Dorsett
Keyword(s):  
Gene Expression ◽  
Chromosome Segregation ◽  
Fluorescence Recovery After Photobleaching ◽  
Partial Loss ◽  
Stable Mode ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
The Stability ◽  
Chromosome Binding

ABSTRACT The cohesin protein complex holds sister chromatids together to ensure proper chromosome segregation upon cell division and also regulates gene transcription. Partial loss of the Nipped-B protein that loads cohesin onto chromosomes, or the Pds5 protein required for sister chromatid cohesion, alters gene expression and organism development, without affecting chromosome segregation. Knowing if a reduced Nipped-B or Pds5 dosage changes how much cohesin binds chromosomes, or the stability with which it binds, is critical information for understanding how cohesin regulates transcription. We addressed this question by in vivo fluorescence recovery after photobleaching (FRAP) with Drosophila salivary glands. Cohesin, Nipped-B, and Pds5 all bind chromosomes in both weak and stable modes, with residence half-lives of some 20 seconds and 6 min, respectively. Reducing the Nipped-B dosage decreases the amount of stable cohesin without affecting its chromosomal residence time, and reducing the Pds5 dosage increases the amount of stable cohesin. This argues that Nipped-B and Pds5 regulate transcription by controlling how much cohesin binds DNA in the stable mode, and not binding affinity. We also found that Nipped-B, Pds5, and the Wapl protein that interacts with Pds5 all play unique roles in cohesin chromosome binding.

scholarly journals The ctf13-30/CTF13 Genomic Haploinsufficiency Modifier Screen Identifies the Yeast Chromatin Remodeling Complex RSC, Which Is Required for the Establishment of Sister Chromatid Cohesion

2004 ◽  
Vol 24 (3) ◽  
pp. 1232-1244 ◽  
Author(s):  
Kristin K. Baetz ◽  
Nevan J. Krogan ◽  
Andrew Emili ◽  
Jack Greenblatt ◽  
Philip Hieter
Keyword(s):  
Chromatin Remodeling ◽  
Chromosome Segregation ◽  
High Fidelity ◽  
Chromosome Transmission ◽  
New Genes ◽  
Sister Chromatids ◽  
Chromatin Remodeling Complex ◽  
Chromatid Cohesion ◽  
Spindle Microtubules ◽  
Mitosis And Meiosis

ABSTRACT The budding yeast centromere-kinetochore complex ensures high-fidelity chromosome segregation in mitosis and meiosis by mediating the attachment and movement of chromosomes along spindle microtubules. To identify new genes and pathways whose function impinges on chromosome transmission, we developed a genomic haploinsufficiency modifier screen and used ctf13-30, encoding a mutant core kinetochore protein, as the reference point. We demonstrate through a series of secondary screens that the genomic modifier screen is a successful method for identifying genes that encode nonessential proteins required for the fidelity of chromosome segregation. One gene isolated in our screen was RSC2, a nonessential subunit of the RSC chromatin remodeling complex. rsc2 mutants have defects in both chromosome segregation and cohesion, but the localization of kinetochore proteins to centromeres is not affected. We determined that, in the absence of RSC2, cohesin could still associate with chromosomes but fails to achieve proper cohesion between sister chromatids, indicating that RSC has a role in the establishment of cohesion. In addition, numerous subunits of RSC were affinity purified and a new component of RSC, Rtt102, was identified. Our work indicates that only a subset of the nonessential RSC subunits function in maintaining chromosome transmission fidelity.

scholarly journals Eco1-dependent cohesin acetylation anchors chromatin loops and cohesion to define functional meiotic chromosome domains

2021 ◽  
Author(s):  
Rachael E Barton ◽  
Lucia F Massari ◽  
Daniel Robertson ◽  
Adele L Marston
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Meiotic Chromosome ◽  
Chromatin Loops ◽  
Meiotic Chromosomes ◽  
Sister Chromatids ◽  
Gamete Formation ◽  
Chromosome Domains ◽  
Chromatid Cohesion ◽  
Cohesin Subunit

Cohesin organizes the genome by forming intra-chromosomal loops and inter-sister chromatid linkages. During gamete formation by meiosis, chromosomes are reshaped to support crossover recombination and two consecutive rounds of chromosome segregation. Here we show that Eco1 acetyltransferase positions both chromatin loops and sister chromatid cohesion to organize meiotic chromosomes into functional domains in budding yeast. Eco1 acetylates the Smc3 cohesin subunit in meiotic S phase to establish chromatin boundaries, independently of DNA replication. Boundary formation by Eco1 is critical for prophase exit and for the maintenance of cohesion until meiosis II, but is independent of the ability of Eco1 to antagonize the cohesin-release factor, Wpl1. Conversely, prevention of cohesin release by Wpl1 is essential for centromeric cohesion, kinetochore monoorientation and co-segregation of sister chromatids in meiosis I. Our findings establish Eco1 as a key determinant of chromatin boundaries and cohesion positioning, revealing how local chromosome structuring directs genome transmission into gametes.

scholarly journals Evidence for cohesin sliding along budding yeast chromosomes

Open Biology ◽  
2016 ◽  
Vol 6 (6) ◽  
pp. 150178 ◽  
Author(s):  
Maria Ocampo-Hafalla ◽  
Sofía Muñoz ◽  
Catarina P. Samora ◽  
Frank Uhlmann
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Budding Yeast ◽  
Transcription Termination ◽  
Gene Activation ◽  
S Phase ◽  
Cohesin Complex ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Active Genes

The ring-shaped cohesin complex is thought to topologically hold sister chromatids together from their synthesis in S phase until chromosome segregation in mitosis. How cohesin stably binds to chromosomes for extended periods, without impeding other chromosomal processes that also require access to the DNA, is poorly understood. Budding yeast cohesin is loaded onto DNA by the Scc2–Scc4 cohesin loader at centromeres and promoters of active genes, from where cohesin translocates to more permanent places of residence at transcription termination sites. Here we show that, at the GAL2 and MET17 loci, pre-existing cohesin is pushed downstream along the DNA in response to transcriptional gene activation, apparently without need for intermittent dissociation or reloading. We observe translocation intermediates and find that the distribution of most chromosomal cohesin is shaped by transcription. Our observations support a model in which cohesin is able to slide laterally along chromosomes while maintaining topological contact with DNA. In this way, stable cohesin binding to DNA and enduring sister chromatid cohesion become compatible with simultaneous underlying chromosomal activities, including but maybe not limited to transcription.

scholarly journals mcl1+, the Schizosaccharomyces pombe Homologue of CTF4, Is Important for Chromosome Replication, Cohesion, and Segregation

2002 ◽  
Vol 1 (5) ◽  
pp. 758-773 ◽  
Author(s):  
Dewight R. Williams ◽  
J. Richard McIntosh
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Fission Yeast ◽  
Chromosome Segregation ◽  
S Phase ◽  
Sister Chromatids ◽  
Eukaryotic Proteins ◽  
Pulsed Field Electrophoresis ◽  
Phase Progression ◽  
Mutant Cells

ABSTRACT The fission yeast minichromosome loss mutant mcl1-1 was identified in a screen for mutants defective in chromosome segregation. Missegregation of the chromosomes in mcl1-1 mutant cells results from decreased centromeric cohesion between sister chromatids. mcl1+ encodes a β-transducin-like protein with similarity to a family of eukaryotic proteins that includes Ctf4p from Saccharomyces cerevisiae, sepB from Aspergillus nidulans, and AND-1 from humans. The previously identified fungal members of this protein family also have chromosome segregation defects, but they primarily affect DNA metabolism. Chromosomes from mcl1-1 cells were heterogeneous in size or structure on pulsed-field electrophoresis gels and had elongated heterogeneous telomeres. mcl1-1 was lethal in combination with the DNA checkpoint mutations rad3Δ and rad26Δ, demonstrating that loss of Mcl1p function leads to DNA damage. mcl1-1 showed an acute sensitivity to DNA damage that affects S-phase progression. It interacts genetically with replication components and causes an S-phase delay when overexpressed. We propose that Mcl1p, like Ctf4p, has a role in regulating DNA replication complexes.

scholarly journals Type 1 protein phosphatase acts in opposition to IpL1 protein kinase in regulating yeast chromosome segregation.

1994 ◽  
Vol 14 (7) ◽  
pp. 4731-4740 ◽  
Author(s):  
L Francisco ◽  
W Wang ◽  
C S Chan
Keyword(s):  
Protein Kinase ◽  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
High Fidelity ◽  
Yeast Saccharomyces Cerevisiae ◽  
M Phase ◽  
Mutant Cells ◽  
Putative Protein Kinase

The IPL1 gene is required for high-fidelity chromosome segregation in the budding yeast Saccharomyces cerevisiae. Conditional ipl1ts mutants missegregate chromosomes severely at 37 degrees C. Here, we report that IPL1 encodes an essential putative protein kinase whose function is required during the later part of each cell cycle. At 26 degrees C, the permissive growth temperature, ipl1 mutant cells are defective in the recovery from a transient G2/M-phase arrest caused by the antimicrotubule drug nocodazole. In an effort to identify additional gene products that participate with the Ipl1 protein kinase in regulating chromosome segregation in yeast, a truncated version of the previously identified DIS2S1/GLC7 gene was isolated as a dosage-dependent suppressor of ipl1ts mutations. DIS2S1/GLC7 is predicted to encode a catalytic subunit (PP1C) of type 1 protein phosphatase. Overexpression of the full-length DIS2S1/GLC7 gene results in chromosome missegregation in wild-type cells and exacerbates the mutant phenotype in ipl1 cells. In addition, the glc7-1 mutation can partially suppress the ipl1-1 mutation. These results suggest that type 1 protein phosphatase acts in opposition to the Ipl1 protein kinase in vivo to ensure the high fidelity of chromosome segregation.

Type 1 protein phosphatase acts in opposition to IpL1 protein kinase in regulating yeast chromosome segregation

1994 ◽  
Vol 14 (7) ◽  
pp. 4731-4740
Author(s):  
L Francisco ◽  
W Wang ◽  
C S Chan
Keyword(s):  
Protein Kinase ◽  
Chromosome Segregation ◽  
Protein Phosphatase ◽  
High Fidelity ◽  
Yeast Saccharomyces Cerevisiae ◽  
M Phase ◽  
Mutant Cells ◽  
Putative Protein Kinase

The IPL1 gene is required for high-fidelity chromosome segregation in the budding yeast Saccharomyces cerevisiae. Conditional ipl1ts mutants missegregate chromosomes severely at 37 degrees C. Here, we report that IPL1 encodes an essential putative protein kinase whose function is required during the later part of each cell cycle. At 26 degrees C, the permissive growth temperature, ipl1 mutant cells are defective in the recovery from a transient G2/M-phase arrest caused by the antimicrotubule drug nocodazole. In an effort to identify additional gene products that participate with the Ipl1 protein kinase in regulating chromosome segregation in yeast, a truncated version of the previously identified DIS2S1/GLC7 gene was isolated as a dosage-dependent suppressor of ipl1ts mutations. DIS2S1/GLC7 is predicted to encode a catalytic subunit (PP1C) of type 1 protein phosphatase. Overexpression of the full-length DIS2S1/GLC7 gene results in chromosome missegregation in wild-type cells and exacerbates the mutant phenotype in ipl1 cells. In addition, the glc7-1 mutation can partially suppress the ipl1-1 mutation. These results suggest that type 1 protein phosphatase acts in opposition to the Ipl1 protein kinase in vivo to ensure the high fidelity of chromosome segregation.

scholarly journals The yeast S phase checkpoint enables replicating chromosomes to bi-orient and restrain spindle extension during S phase distress

2005 ◽  
Vol 168 (7) ◽  
pp. 999-1012 ◽  
Author(s):  
Jeff Bachant ◽  
Shannon R. Jessen ◽  
Sarah E. Kavanaugh ◽  
Candida S. Fielding
Keyword(s):  
Dna Replication ◽  
Chromosome Segregation ◽  
Replication Fork ◽  
S Phase ◽  
Origin Of Replication ◽  
Independent Manner ◽  
Checkpoint Signaling ◽  
Hydroxyurea Treatment ◽  
Chromatid Cohesion ◽  
S Phase Checkpoint

The budding yeast S phase checkpoint responds to hydroxyurea-induced nucleotide depletion by preventing replication fork collapse and the segregation of unreplicated chromosomes. Although the block to chromosome segregation has been thought to occur by inhibiting anaphase, we show checkpoint-defective rad53 mutants undergo cycles of spindle extension and collapse after hydroxyurea treatment that are distinct from anaphase cells. Furthermore, chromatid cohesion, whose dissolution triggers anaphase, is dispensable for S phase checkpoint arrest. Kinetochore–spindle attachments are required to prevent spindle extension during replication blocks, and chromosomes with two centromeres or an origin of replication juxtaposed to a centromere rescue the rad53 checkpoint defect. These observations suggest that checkpoint signaling is required to generate an inward force involved in maintaining preanaphase spindle integrity during DNA replication distress. We propose that by promoting replication fork integrity under these conditions Rad53 ensures centromere duplication. Replicating chromosomes can then bi-orient in a cohesin-independent manner to restrain untimely spindle extension.

scholarly journals Pericentric chromatin loops function as a nonlinear spring in mitotic force balance

2013 ◽  
Vol 200 (6) ◽  
pp. 757-772 ◽  
Author(s):  
Andrew D. Stephens ◽  
Rachel A. Haggerty ◽  
Paula A. Vasquez ◽  
Leandra Vicci ◽  
Chloe E. Snider ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Force Balance ◽  
Nonlinear Spring ◽  
Sister Chromatids ◽  
Spindle Dynamics ◽  
Restoring Forces ◽  
Cross Links ◽  
Mean And Variance

The mechanisms by which sister chromatids maintain biorientation on the metaphase spindle are critical to the fidelity of chromosome segregation. Active force interplay exists between predominantly extensional microtubule-based spindle forces and restoring forces from chromatin. These forces regulate tension at the kinetochore that silences the spindle assembly checkpoint to ensure faithful chromosome segregation. Depletion of pericentric cohesin or condensin has been shown to increase the mean and variance of spindle length, which have been attributed to a softening of the linear chromatin spring. Models of the spindle apparatus with linear chromatin springs that match spindle dynamics fail to predict the behavior of pericentromeric chromatin in wild-type and mutant spindles. We demonstrate that a nonlinear spring with a threshold extension to switch between spring states predicts asymmetric chromatin stretching observed in vivo. The addition of cross-links between adjacent springs recapitulates coordination between pericentromeres of neighboring chromosomes.

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