scholarly journals The acetyltransferase activity of San stabilizes the mitotic cohesin at the centromeres in a shugoshin-independent manner

2007 ◽  
Vol 177 (4) ◽  
pp. 587-597 ◽  
Author(s):  
Fajian Hou ◽  
Chih-Wen Chu ◽  
Xiangduo Kong ◽  
Kyoko Yokomori ◽  
Hui Zou
Keyword(s):  
Cell Cycle ◽  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Independent Manner ◽  
Acetyltransferase Activity ◽  
Chromatid Cohesion ◽  
Interphase Cells ◽  
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Proper sister chromatid cohesion is critical for maintaining genetic stability. San is a putative acetyltransferase that is important for sister chromatid cohesion in Drosophila melanogaster, but not in budding yeast. We showed that San is critical for sister chromatid cohesion in HeLa cells, suggesting that this mechanism may be conserved in metazoans. Furthermore, although a small fraction of San interacts with the NatA complex, San appears to mediate cohesion independently. San exhibits acetyltransferase activity in vitro, and its activity is required for sister chromatid cohesion in vivo. In the absence of San, Sgo1 localizes correctly throughout the cell cycle. However, cohesin is no longer detected at the mitotic centromeres. Furthermore, San localizes to the cytoplasm in interphase cells; thus, it may not gain access to chromosomes until mitosis. Moreover, in San-depleted cells, further depletion of Plk1 rescues the cohesion along the chromosome arms, but not at the centromeres. Collectively, San may be specifically required for the maintenance of the centromeric cohesion in mitosis.

scholarly journals Acetylation of the SUN protein Mps3 by Eco1 regulates its function in nuclear organization

2012 ◽  
Vol 23 (13) ◽  
pp. 2546-2559 ◽  
Author(s):  
Suman Ghosh ◽  
Jennifer M. Gardner ◽  
Christine J. Smoyer ◽  
Jennifer M. Friederichs ◽  
Jay R. Unruh ◽  
...  
Keyword(s):  
Nuclear Membrane ◽  
Sister Chromatid ◽  
Transmembrane Domain ◽  
Nuclear Organization ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Sister Chromatid Cohesion ◽  
Chromatid Cohesion

The Saccharomyces cerevisiae SUN-domain protein Mps3 is required for duplication of the yeast centrosome-equivalent organelle, the spindle pole body (SPB), and it is involved in multiple aspects of nuclear organization, including telomere tethering and gene silencing at the nuclear membrane, establishment of sister chromatid cohesion, and repair of certain types of persistent DNA double-stranded breaks. How these diverse SUN protein functions are regulated is unknown. Here we show that the Mps3 N-terminus is a substrate for the acetyltransferase Eco1/Ctf7 in vitro and in vivo and map the sites of acetylation to three lysine residues adjacent to the Mps3 transmembrane domain. Mutation of these residues shows that acetylation is not essential for growth, SPB duplication, or distribution in the nuclear membrane. However, analysis of nonacetylatable mps3 mutants shows that this modification is required for accurate sister chromatid cohesion and for chromosome recruitment to the nuclear membrane. Acetylation of Mps3 by Eco1 is one of the few regulatory mechanisms known to control nuclear organization.

scholarly journals Cohesin architecture and clustering in vivo

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Siheng Xiang ◽  
Douglas Koshland
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Transcription Regulation ◽  
Sister Chromatid ◽  
Coiled Coil ◽  
Sister Chromatid Cohesion ◽  
Chromosome Condensation ◽  
Cohesin Complex ◽  
Chromatid Cohesion

Cohesin helps mediate sister chromatid cohesion, chromosome condensation, DNA repair, and transcription regulation. We exploited proximity-dependent labeling to define the in vivo interactions of cohesin domains with DNA or with other cohesin domains that lie within the same or in different cohesin complexes. Our results suggest that both cohesin's head and hinge domains are proximal to DNA, and cohesin structure is dynamic with differential folding of its coiled coil regions to generate butterfly confirmations. This method also reveals that cohesins form ordered clusters on and off DNA. The levels of cohesin clusters and their distribution on chromosomes are cell cycle-regulated. Cohesin clustering is likely necessary for cohesion maintenance because clustering and maintenance uniquely require the same subset of cohesin domains and the auxiliary cohesin factor Pds5p. These conclusions provide important new mechanistic and biological insights into the architecture of the cohesin complex, cohesin–cohesin interactions, and cohesin's tethering and loop-extruding activities.

scholarly journals Two Human Orthologues of Eco1/Ctf7 Acetyltransferases Are Both Required for Proper Sister-Chromatid Cohesion

2005 ◽  
Vol 16 (8) ◽  
pp. 3908-3918 ◽  
Author(s):  
Fajian Hou ◽  
Hui Zou
Keyword(s):  
Sister Chromatid ◽  
Cell Cycle Regulation ◽  
Sister Chromatid Cohesion ◽  
Genetic Studies ◽  
Conserved Domain ◽  
Chromatid Cohesion ◽  
The Difference ◽  
Cycle Regulation ◽  
Acetyltransferase Domain

Genetic studies in yeast and Drosophila have uncovered a conserved acetyltransferase involved in sister-chromatid cohesion. Here, we described the two human orthologues, previously named EFO1/ESCO1 and EFO2/ESCO2. Similar to their yeast (Eco1/Ctf7 and Eso1) and fly (deco) counterparts, both proteins feature a conserved C-terminal domain consisting of a H2C2 zinc finger motif and an acetyltransferase domain that is able to catalyze autoacetylation reaction in vitro. However, no similarity can be detected outside of the conserved domain. RNA interference depletion experiment revealed that EFO1/ESCO1 and EFO2/ESCO2 were not redundant and that both were required for proper sister-chromatid cohesion. The difference between EFO1 and EFO2 also is reflected in their cell cycle regulation. In mitosis, EFO1 is phosphorylated, whereas EFO2 is degraded. Furthermore, both proteins associate with chromosomes, and the chromosome binding depends on the diverse N-terminal domains. We propose that EFO1 and EFO2 are targeted to different chromosome structures to help establish or maintain sister-chromatid cohesion.

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 Interaction of D-type cyclins with a novel myb-like transcription factor, DMP1.

1996 ◽  
Vol 16 (11) ◽  
pp. 6457-6467 ◽  
Author(s):  
H Hirai ◽  
C J Sherr
Keyword(s):  
Cell Cycle ◽  
S Phase ◽  
Cyclin D ◽  
Independent Manner ◽  
Consensus Sequences ◽  
Representative Cell ◽  
Mouse Tissues ◽  
Phase Entry

The cyclin D-dependent kinases CDK4 and CDK6 trigger phosphorylation of the retinoblastoma protein (RB) late in G1 phase, helping to cancel its growth-suppressive function and thereby facilitating S-phase entry. Although specific inhibition of cyclin D-dependent kinase activity in vivo can prevent cells from entering S phase, it does not affect S-phase entry in cells lacking functional RB, implying that RB may be the only substrate of CDK4 and CDK6 whose phosphorylation is necessary for G1 exit. Using a yeast two-hybrid interactive screen, we have now isolated a novel cyclin D-interacting myb-like protein (designated DMP1), which binds specifically to the nonamer DNA consensus sequences CCCG(G/T)ATGT to activate transcription. A subset of these DMP1 recognition sequences containing a GGA trinucleotide core can also function as Ets-responsive elements. DMP1 mRNA and protein are ubiquitously expressed throughout the cell cycle in mouse tissues and in representative cell lines. DMP1 binds to D-type cyclins directly in vitro and when coexpressed in insect Sf9 cells. In both settings, it can be phosphorylated by cyclin D-dependent kinases, suggesting that its transcriptional activity may normally be regulated through such mechanisms. These results raise the possibility that cyclin D-dependent kinases regulate gene expression in an RB independent manner, thereby serving to link other genetic programs to the cell cycle clock.

scholarly journals A Potential Role for Human Cohesin in Mitotic Spindle Aster Assembly

2001 ◽  
Vol 276 (50) ◽  
pp. 47575-47582 ◽  
Author(s):  
Heather C. Gregson ◽  
John A. Schmiesing ◽  
Jong-Soo Kim ◽  
Toshiki Kobayashi ◽  
Sharleen Zhou ◽  
...  
Keyword(s):  
Sister Chromatid ◽  
Mitotic Spindle ◽  
Potential Role ◽  
Metaphase Plate ◽  
Spindle Pole ◽  
Sister Chromatid Cohesion ◽  
Cycle Arrest ◽  
Spindle Poles ◽  
Chromatid Cohesion

The cohesin multiprotein complex containing SMC1, SMC3, Scc3 (SA), and Scc1 (Rad21) is required for sister chromatid cohesion in eukaryotes. Although metazoan cohesin associates with chromosomes and was shown to function in the establishment of sister chromatid cohesion during interphase, the majority of cohesin was found to be off chromosomes and reside in the cytoplasm in metaphase. Despite its dissociation from chromosomes, however, microinjection of an antibody against human SMC1 led to disorganization of the metaphase plate and cell cycle arrest, indicating that human cohesin still plays an important role in metaphase. To address the mitotic function of human cohesin, the subcellular localization of cohesin components was reexamined in human cells. Interestingly, we found that cohesin localizes to the spindle poles during mitosis and interacts with NuMA, a spindle pole-associated factor required for mitotic spindle organization. The interaction with NuMA persists during interphase. Similar to NuMA, a significant amount of cohesin was found to associate with the nuclear matrix. Furthermore, in the absence of cohesin, mitotic spindle asters failed to formin vitro. Our results raise the intriguing possibility that in addition to its well demonstrated function in sister chromatid cohesion, cohesin may be involved in spindle assembly during mitosis.

scholarly journals ATP dependent DNA transport within cohesin: Scc2 clamps DNA on top of engaged heads while Scc3 promotes entrapment within the SMC-kleisin ring

2020 ◽  
Author(s):  
James E Collier ◽  
Byung-Gil Lee ◽  
Maurici B Roig ◽  
Stanislav Yatskevich ◽  
Naomi J Petela ◽  
...  
Keyword(s):  
Sister Chromatid ◽  
Atp Hydrolysis ◽  
Sister Chromatid Cohesion ◽  
S Phase ◽  
Coiled Coils ◽  
Rigorous Proof ◽  
Dna Loops ◽  
Dna Transport ◽  
Chromatid Cohesion

SUMMARYIn addition to extruding DNA loops, cohesin entraps within its SMC-kleisin ring (S-K) individual DNAs during G1 and sister DNAs during S-phase. All three activities require related hook-shaped proteins called Scc2 and Scc3. Using thiol-specific crosslinking we provide rigorous proof of entrapment activity in vitro. Scc2 alone promotes entrapment of DNAs in the E-S and E-K compartments, between ATP-bound engaged heads and the SMC hinge and associated kleisin, respectively. This does not require ATP hydrolysis nor is it accompanied by entrapment within S-K rings, which is a slower process requiring Scc3. Cryo-EM reveals that DNAs transported into E-S/E-K compartments are “clamped” in a sub-compartment created by Scc2’s association with engaged heads whose coiled coils are folded around their elbow. We suggest that clamping may be a recurrent feature of cohesin complexes active in loop extrusion and that this conformation precedes the S-K entrapment required for sister chromatid cohesion.

scholarly journals Cohesin in space and time: architecture and oligomerization in vivo

2020 ◽  
Author(s):  
Siheng Xiang ◽  
Douglas Koshland
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Transcription Regulation ◽  
Sister Chromatid ◽  
Critical Role ◽  
Coiled Coils ◽  
Biological Functions ◽  
Chromatid Cohesion ◽  
And Function

AbstractCohesin helps mediate sister chromatid cohesion, chromosome condensation, DNA repair and transcription regulation. Cohesin can tether two regions of DNA and can also extrude DNA loops. We interrogated cohesin architecture, oligomerization state and function of cohesin oligomers in vivo through proximity-dependent labeling of cohesin domains. Our results suggest that the hinge and head domains of cohesin both bind DNA, and that cohesin coiled coils bend, bringing the head and hinge together to form a butterfly conformation. Our data also suggest that cohesin efficiently oligomerizes on and off DNA. The levels of oligomers and their distribution on chromosomes are cell cycle regulated. Cohesin oligomerization is blocked by mutations in distinct domains of Smc3p and Mcd1p, or depletion of Pds5p. This unusual subset of mutations specifically blocks the maintenance of cohesion and condensation, suggesting that cohesin oligomerization plays a critical role in these biological functions.

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