scholarly journals Scc2/Nipbl hops between chromosomal cohesin rings after loading

2017 ◽  
Author(s):  
James D.P. Rhodes ◽  
Davide Mazza ◽  
Kim A. Nasmyth ◽  
Stephan Uphoff
Keyword(s):  
Single Molecule ◽  
Sister Chromatid ◽  
Fluorescence Recovery After Photobleaching ◽  
Sister Chromatid Cohesion ◽  
Dna Looping ◽  
Cohesin Complex ◽  
Single Molecule Tracking ◽  
Loading Function ◽  
Stop And Go ◽  
Chromatid Cohesion

AbstractThe cohesin complex mediates DNA-DNA interactions both between (sister chromatid cohesion) and within chromosomes (DNA looping) via a process thought to involve entrapment of DNAs within its tripartite ring. It has been suggested that intra- chromosome loops are generated through processive extrusion of DNAs through the lumen of cohesin’s ring. Scc2 (Nipbl) is essential for loading cohesin onto chromosomes but not for maintaining sister chromatid cohesion following DNA replication. It has therefore been assumed that Scc2 is involved exclusively in the cohesin loading process. However, it is possible that the stimulation of cohesin’s ABC-like ATPase by Scc2 also has a post-loading function, for example driving loop extrusion. Using fluorescence recovery after photobleaching (FRAP) and single-molecule tracking, we show that Scc2 binds dynamically to chromatin, principally through an association with cohesin. Scc2’s movement within chromatin is consistent with a “stop-and-go” or “hopping” motion. We suggest that a low diffusion coefficient, a low stoichiometry relative to cohesin, and a high affinity for chromosomal cohesin enables Scc2 to move rapidly from one chromosomal cohesin complex to another, performing a function distinct from loading.

scholarly journals Scc2/Nipbl hops between chromosomal cohesin rings after loading

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
James Rhodes ◽  
Davide Mazza ◽  
Kim Nasmyth ◽  
Stephan Uphoff
Keyword(s):  
Single Molecule ◽  
Fluorescence Recovery After Photobleaching ◽  
Dna Looping ◽  
Cohesin Complex ◽  
Dna Interactions ◽  
Single Molecule Tracking ◽  
Loading Function ◽  
Stop And Go ◽  
Chromatid Cohesion ◽  
Stimulation Of

The cohesin complex mediates DNA-DNA interactions both between (sister chromatid cohesion) and within chromosomes (DNA looping). It has been suggested that intra-chromosome loops are generated by extrusion of DNAs through the lumen of cohesin’s ring. Scc2 (Nipbl) stimulates cohesin’s ABC-like ATPase and is essential for loading cohesin onto chromosomes. However, it is possible that the stimulation of cohesin’s ATPase by Scc2 also has a post-loading function, for example driving loop extrusion. Using fluorescence recovery after photobleaching (FRAP) and single-molecule tracking in human cells, we show that Scc2 binds dynamically to chromatin, principally through an association with cohesin. Scc2’s movement within chromatin is consistent with a 'stop-and-go' or 'hopping' motion. We suggest that a low diffusion coefficient, a low stoichiometry relative to cohesin, and a high affinity for chromosomal cohesin enables Scc2 to move rapidly from one chromosomal cohesin complex to another, performing a function distinct from loading.

scholarly journals Absence of the Spindle Assembly Checkpoint restores mitotic fidelity upon loss of sister chromatid cohesion

2018 ◽  
Author(s):  
Rui D. Silva ◽  
Mihailo Mirkovic ◽  
Leonardo G. Guilgur ◽  
Om S. Rathore ◽  
Rui Gonçalo Martinho ◽  
...  
Keyword(s):  
Cell Survival ◽  
Sister Chromatid ◽  
Spindle Assembly Checkpoint ◽  
Genome Shuffling ◽  
Spindle Assembly ◽  
Sister Chromatid Cohesion ◽  
Abnormal Development ◽  
Wing Development ◽  
Cohesin Complex ◽  
Chromatid Cohesion

AbstractSister chromatid cohesion is essential for faithful mitosis, as premature cohesion loss leads to random chromosome segregation and aneuploidy, resulting in abnormal development. To identify specific conditions capable of restoring defects associated with cohesion loss, we screened for genes whose depletion modulates Drosophila wing development when sister chromatid cohesion is impaired. Cohesion deficiency was induced by knock-down of the acetyltransferase Separation anxiety (San)/Naa50, a cohesin complex stabilizer. Several genes whose function impacts wing development upon cohesion loss were identified. Surprisingly, knockdown of key Spindle Assembly Checkpoint (SAC) proteins, Mad2 and Mps1, suppressed developmental defects associated with San depletion. SAC impairment upon cohesin removal, triggered by San depletion or artificial removal of the cohesin complex, prevented extensive genome shuffling, reduced segregation defects and restored cell survival. This counterintuitive phenotypic suppression was caused by an intrinsic bias for efficient chromosome bi-orientation at mitotic entry, coupled with slow engagement of error-correction reactions. We conclude that mitotic timing determines the severity of defects associated with cohesion deficiency. Therefore, although divisions are still error-prone, SAC inactivation enhances cell survival and tissue homeostasis upon cohesion loss.

scholarly journals Pds5p regulates the maintenance of sister chromatid cohesion and is sumoylated to promote the dissolution of cohesion

2003 ◽  
Vol 163 (4) ◽  
pp. 729-741 ◽  
Author(s):  
Kristen Stead ◽  
Cristina Aguilar ◽  
Theresa Hartman ◽  
Melissa Drexel ◽  
Pamela Meluh ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Temperature Sensitivity ◽  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Cohesin Complex ◽  
Chromatid Cohesion ◽  
Chromosomal Loci

Pds5p and the cohesin complex are required for sister chromatid cohesion and localize to the same chromosomal loci over the same cell cycle window. However, Pds5p and the cohesin complex likely have distinct roles in cohesion. We report that pds5 mutants establish cohesion, but during mitosis exhibit precocious sister dissociation. Thus, unlike the cohesin complex, which is required for cohesion establishment and maintenance, Pds5p is required only for maintenance. We identified SMT4, which encodes a SUMO isopeptidase, as a high copy suppressor of both the temperature sensitivity and precocious sister dissociation of pds5 mutants. In contrast, SMT4 does not suppress temperature sensitivity of cohesin complex mutants. Pds5p is SUMO conjugated, with sumoylation peaking during mitosis. SMT4 overexpression reduces Pds5p sumoylation, whereas smt4 mutants have increased Pds5p sumoylation. smt4 mutants were previously shown to be defective in cohesion maintenance during mitosis. These data provide the first link between a protein required for cohesion, Pds5p, and sumoylation, and suggest that Pds5p sumoylation promotes the dissolution of cohesion.

scholarly journals A conserved activity for cohesin in bridging DNA molecules

2019 ◽  
Author(s):  
Pilar Gutierrez-Escribano ◽  
Matthew D. Newton ◽  
Aida Llauró ◽  
Jonas Huber ◽  
Loredana Tanasie ◽  
...  
Keyword(s):  
Single Molecule ◽  
Sister Chromatid ◽  
Regulation Of Gene Expression ◽  
Sister Chromatid Cohesion ◽  
Dna Molecules ◽  
Chromosome Architecture ◽  
Physiological Conditions ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Core Activity

AbstractEssential processes such as accurate chromosome segregation, regulation of gene expression and DNA repair rely on protein-mediated DNA tethering. Sister chromatid cohesion requires the SMC complex cohesin to act as a protein linker that holds replicated chromatids together (1, 2). The molecular mechanism by which cohesins hold sister chromatids has remained controversial. Here, we used a single molecule approach to visualise the activity of cohesin complexes as they hold DNA molecules. We describe a DNA bridging activity that requires ATP and is conserved from yeast to human cohesin. We show that cohesin can form two distinct classes of bridges at physiological conditions, a “permanent bridge” able to resists high force (over 80pN) and a “reversible bridge” that breaks at lower forces (5-40pN). Both classes of bridges require Scc2/Scc4 in addition to ATP. We demonstrate that bridge formation requires physical proximity of the DNA segments to be tethered and show that “permanent” cohesin bridges can move between two DNA molecules but cannot be removed from DNA when they occur in cis. This suggests that separate physical compartments in cohesin molecules are involved in the bridge. Finally, we show that cohesin tetramers, unlike condensin, cannot compact linear DNA molecules against low force, demonstrating that the core activity of cohesin tetramers is bridging DNA rather than compacting it. Our findings carry important implications for the understanding of the basic mechanisms behind cohesin-dependent establishment of sister chromatid cohesion and chromosome architecture.

scholarly journals Hardwired synthetic lethality within the cohesin complex in human cancer cells

2017 ◽  
Author(s):  
Petra van der Lelij ◽  
Simone Lieb ◽  
Julian Jude ◽  
Gordana Wutz ◽  
Catarina P. Santos ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Cancer Cells ◽  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Cohesin Complex ◽  
Wild Type ◽  
Synthetic Lethal ◽  
Recurrent Mutations ◽  
Wide Range ◽  
Chromatid Cohesion

AbstractRecent genome analyses have identified recurrent mutations in the cohesin complex in a wide range of human cancers. Here we demonstrate that the most frequently mutated subunit of the cohesin complex, STAG2, displays a strong synthetic lethal interaction with its paralog STAG1. Mechanistically, STAG1 loss abrogates sister chromatid cohesion in STAG2 mutated but not in wild-type cells leading to mitotic catastrophe, defective cell division and apoptosis. STAG1 inactivation inhibits the proliferation of STAG2 mutated but not wild-type bladder cancer and Ewing sarcoma cell lines. Restoration of STAG2 expression in a mutated bladder cancer model alleviates the dependency on STAG1. Thus, STAG1 and STAG2 act redundantly to support sister chromatid cohesion and cell survival. STAG1 represents a hardwired, context independent vulnerability of cancer cells carrying mutations in the major emerging tumor suppressor STAG2. Exploiting synthetic lethal interactions to target recurrent cohesin mutations in cancer, e.g. by inhibiting STAG1, holds the promise for the development of selective therapeutics.

scholarly journals Synthetic lethality between the cohesin subunits STAG1 and STAG2 in diverse cancer contexts

2017 ◽  
Author(s):  
Petra van der Lelij ◽  
Simone Lieb ◽  
Julian Jude ◽  
Gordana Wutz ◽  
Catarina P. Santos ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Sister Chromatid ◽  
Synthetic Lethality ◽  
Sister Chromatid Cohesion ◽  
Cohesin Complex ◽  
Wild Type ◽  
Synthetic Lethal ◽  
Recurrent Mutations ◽  
Wide Range ◽  
Chromatid Cohesion

AbstractRecent genome analyses have identified recurrent mutations in the cohesin complex in a wide range of human cancers. Here we demonstrate that the most frequently mutated subunit of the cohesin complex, STAG2, displays a strong synthetic lethal interaction with its paralog STAG1. Mechanistically, STAG1 loss abrogates sister chromatid cohesion in STAG2 mutated but not in wild-type cells leading to mitotic catastrophe, defective cell division and apoptosis. STAG1 inactivation inhibits the proliferation of STAG2 mutated but not wild-type bladder cancer and Ewing sarcoma cell lines. Restoration of STAG2 expression in a mutated bladder cancer model alleviates the dependency on STAG1. Thus, STAG1 and STAG2 support sister chromatid cohesion to redundantly ensure cell survival. STAG1 represents a vulnerability of cancer cells carrying mutations in the major emerging tumor suppressor STAG2 across different cancer contexts. Exploiting synthetic lethal interactions to target recurrent cohesin mutations in cancer, e.g. by inhibiting STAG1, holds the promise for the development of selective therapeutics.

scholarly journals Towards a Structural Mechanism for Sister Chromatid Cohesion Establishment at the Eukaryotic Replication Fork

Biology ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 466
Author(s):  
Sarah S. Henrikus ◽  
Alessandro Costa
Keyword(s):  
Single Molecule ◽  
Sister Chromatid ◽  
Replication Fork ◽  
Genetic Material ◽  
Sister Chromatid Cohesion ◽  
Duplex Dna ◽  
Structural Mechanism ◽  
Chromatin Dynamics ◽  
Chromatid Cohesion ◽  
Replication Factors

Cohesion between replicated chromosomes is essential for chromatin dynamics and equal segregation of duplicated genetic material. In the G1 phase, the ring-shaped cohesin complex is loaded onto duplex DNA, enriching at replication start sites, or “origins”. During the same phase of the cell cycle, and also at the origin sites, two MCM helicases are loaded as symmetric double hexamers around duplex DNA. During the S phase, and through the action of replication factors, cohesin switches from encircling one parental duplex DNA to topologically enclosing the two duplicated DNA filaments, which are known as sister chromatids. Despite its vital importance, the structural mechanism leading to sister chromatid cohesion establishment at the replication fork is mostly elusive. Here we review the current understanding of the molecular interactions between the replication machinery and cohesin, which support sister chromatid cohesion establishment and cohesin function. In particular, we discuss how cryo-EM is shedding light on the mechanisms of DNA replication and cohesin loading processes. We further expound how frontier cryo-EM approaches, combined with biochemistry and single-molecule fluorescence assays, can lead to understanding the molecular basis of sister chromatid cohesion establishment at the replication fork.

scholarly journals Interallelic complementation provides functional evidence for cohesin–cohesin interactions on DNA

2015 ◽  
Vol 26 (23) ◽  
pp. 4224-4235 ◽  
Author(s):  
Thomas Eng ◽  
Vincent Guacci ◽  
Douglas Koshland
Keyword(s):  
Sister Chromatid ◽  
Single Copy ◽  
Sister Chromatid Cohesion ◽  
Multiple Roles ◽  
Restrictive Temperature ◽  
Cohesin Complex ◽  
Chromosome Architecture ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Interallelic Complementation

The cohesin complex (Mcd1p, Smc1p, Smc3p, and Scc3p) has multiple roles in chromosome architecture, such as promoting sister chromatid cohesion, chromosome condensation, DNA repair, and transcriptional regulation. The prevailing embrace model for sister chromatid cohesion posits that a single cohesin complex entraps both sister chromatids. We report interallelic complementation between pairs of nonfunctional mcd1 alleles (mcd1-1 and mcd1-Q266) or smc3 alleles (smc3-42 and smc3-K113R). Cells bearing individual mcd1 or smc3 mutant alleles are inviable and defective for both sister chromatid cohesion and condensation. However, cells coexpressing two defective mcd1 or two defective smc3 alleles are viable and have cohesion and condensation. Because cohesin contains only a single copy of Smc3p or Mcd1p, these examples of interallelic complementation must result from interplay or communication between the two defective cohesin complexes, each harboring one of the mutant allele products. Neither mcd1-1p nor smc3-42p is bound to chromosomes when expressed individually at its restrictive temperature. However, their chromosome binding is restored when they are coexpressed with their chromosome-bound interallelic complementing partner. Our results support a mechanism by which multiple cohesin complexes interact on DNA to mediate cohesion and condensation.

scholarly journals Synthetic lethality between the cohesin subunits STAG1 and STAG2 in diverse cancer contexts

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Petra van der Lelij ◽  
Simone Lieb ◽  
Julian Jude ◽  
Gordana Wutz ◽  
Catarina P Santos ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Sister Chromatid ◽  
Synthetic Lethality ◽  
Sister Chromatid Cohesion ◽  
Cohesin Complex ◽  
Wild Type ◽  
Synthetic Lethal ◽  
Recurrent Mutations ◽  
Wide Range ◽  
Chromatid Cohesion

Recent genome analyses have identified recurrent mutations in the cohesin complex in a wide range of human cancers. Here we demonstrate that the most frequently mutated subunit of the cohesin complex, STAG2, displays a strong synthetic lethal interaction with its paralog STAG1. Mechanistically, STAG1 loss abrogates sister chromatid cohesion in STAG2 mutated but not in wild-type cells leading to mitotic catastrophe, defective cell division and apoptosis. STAG1 inactivation inhibits the proliferation of STAG2 mutated but not wild-type bladder cancer and Ewing sarcoma cell lines. Restoration of STAG2 expression in a mutated bladder cancer model alleviates the dependency on STAG1. Thus, STAG1 and STAG2 support sister chromatid cohesion to redundantly ensure cell survival. STAG1 represents a vulnerability of cancer cells carrying mutations in the major emerging tumor suppressor STAG2 across different cancer contexts. Exploiting synthetic lethal interactions to target recurrent cohesin mutations in cancer, e.g. by inhibiting STAG1, holds the promise for the development of selective therapeutics.

scholarly journals Pds5p Is an Essential Chromosomal Protein Required for Both Sister Chromatid Cohesion and Condensation in Saccharomyces cerevisiae

2000 ◽  
Vol 151 (3) ◽  
pp. 613-626 ◽  
Author(s):  
Theresa Hartman ◽  
Kristen Stead ◽  
Douglas Koshland ◽  
Vincent Guacci
Keyword(s):  
Sister Chromatid ◽  
Chromosome Structure ◽  
Essential Gene ◽  
Sister Chromatid Cohesion ◽  
Genetic Screen ◽  
S Phase ◽  
Chromosomal Protein ◽  
Cohesin Complex ◽  
Chromatid Cohesion ◽  
The Times

The PDS5 gene (precocious dissociation of sisters) was identified in a genetic screen designed to identify genes important for chromosome structure. PDS5 is an essential gene and homologues are found from yeast to humans. Pds5p function is important for viability from S phase through mitosis and localizes to chromosomes during this cell cycle window, which encompasses the times when sister chromatid cohesion exists. Pds5p is required to maintain cohesion at centromere proximal and distal sequences. These properties are identical to those of the four cohesion complex members Mcd1p/Scc1p, Smc1p, Smc3p, and Scc3p/Irr1p (Guacci, V., D. Koshland, and A. Strunnikov. 1997. Cell. 91:47–57; Michaelis, C., R. Ciosk, and K. Nasmyth. 1997. Cell. 91:35–45; Toth, A., R. Ciosk, F. Uhlmann, M. Galova, A. Schleiffer, and K. Nasmyth. 1999. Genes Dev. 13:307–319). Pds5p binds to centromeric and arm sequences bound by Mcd1p. Furthermore, Pds5p localization to chromosomes is dependent on Mcd1p. Thus, Pds5p, like the cohesin complex members, is a component of the molecular glue that mediates sister chromatid cohesion. However, Mcd1p localization to chromosomes is independent of Pds5p, which may reflect differences in their roles in cohesion. Finally, Pds5p is required for condensation as well as cohesion, which confirms the link between these processes revealed through analysis of Mcd1p (Guacci, V., D. Koshland, and A. Strunnikov. 1997. Cell. 91:47–57). Therefore, the link between cohesion and condensation is a general property of yeast chromosomes.

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