Association of mammalian SMC1 and SMC3 proteins with meiotic chromosomes and synaptonemal complexes

2000 ◽  
Vol 113 (4) ◽  
pp. 673-682 ◽  
Author(s):  
M. Eijpe ◽  
C. Heyting ◽  
B. Gross ◽  
R. Jessberger
Keyword(s):  
Gene Dosage ◽  
Dna Recombination ◽  
Immunofluorescence Analysis ◽  
Synaptonemal Complexes ◽  
Meiotic Chromosomes ◽  
Chromatid Cohesion ◽  
Specific Proteins ◽  
Experimental Approaches ◽  
Structural Maintenance Of Chromosomes ◽  
Smc Proteins

In somatic cells, the heterodimeric Structural Maintenance of Chromosomes (SMC) proteins are involved in chromosome condensation and gene dosage compensation (SMC2 and 4), and sister chromatid cohesion and DNA recombination (SMC1 and 3). We report here evidence for an involvement of mammalian SMC1 and SMC3 proteins in meiosis. Immunofluorescence analysis of testis sections showed intense chromatin association in meiotic prophase cells, weaker staining in round spermatids and absence of the SMC proteins in elongated spermatids. In spermatocyte nuclei spreads, the SMC1 and SMC3 proteins localize in a beaded structure along the axial elements of synaptonemal complexes of pachytene and diplotene chromosomes. Both SMC proteins are present in rat spermatocytes and enriched in preparations of synaptonemal complexes. Several independent experimental approaches revealed interactions of the SMC proteins with synaptonemal complex-specific proteins SCP2 and SCP3. These results suggest a model for the arrangement of SMC proteins in mammalian meiotic chromatin.

scholarly journals Novel Meiosis-Specific Isoform of Mammalian SMC1

2001 ◽  
Vol 21 (20) ◽  
pp. 6984-6998 ◽  
Author(s):  
E. Revenkova ◽  
M. Eijpe ◽  
C. Heyting ◽  
B. Gross ◽  
R. Jessberger
Keyword(s):  
Mammalian Cells ◽  
Dna Recombination ◽  
Protein Isoforms ◽  
Yeast Genome ◽  
Cell Type ◽  
Late Pachytene ◽  
Nuclear Extracts ◽  
Chromatid Cohesion ◽  
Structural Maintenance Of Chromosomes ◽  
Smc Proteins

ABSTRACT Structural maintenance of chromosomes (SMC) proteins fulfill pivotal roles in chromosome dynamics. In yeast, the SMC1-SMC3 heterodimer is required for meiotic sister chromatid cohesion and DNA recombination. Little is known, however, about mammalian SMC proteins in meiotic cells. We have identified a novel SMC protein (SMC1β), which—except for a unique, basic, DNA binding C-terminal motif—is highly homologous to SMC1 (which may now be called SMC1α) and is not present in the yeast genome. SMC1β is specifically expressed in testes and coimmunoprecipitates with SMC3 from testis nuclear extracts, but not from a variety of somatic cells. This establishes for mammalian cells the concept of cell-type- and tissue-specific SMC protein isoforms. Analysis of testis sections and chromosome spreads of various stages of meiosis revealed localization of SMC1β along the axial elements of synaptonemal complexes in prophase I. Most SMC1β dissociates from the chromosome arms in late-pachytene-diplotene cells. However, SMC1β, but not SMC1α, remains chromatin associated at the centromeres up to metaphase II. Thus, SMC1β and not SMC1α is likely involved in maintaining cohesion between sister centromeres until anaphase II.

scholarly journals Condensin and cohesin display different arm conformations with characteristic hinge angles

2002 ◽  
Vol 156 (3) ◽  
pp. 419-424 ◽  
Author(s):  
David E. Anderson ◽  
Ana Losada ◽  
Harold P. Erickson ◽  
Tatsuya Hirano
Keyword(s):  
Catalytic Domain ◽  
Protein Complexes ◽  
Coiled Coil ◽  
Coiled Coils ◽  
Structure Characteristic ◽  
Catalytic Domains ◽  
Open Conformation ◽  
Chromatid Cohesion ◽  
Structural Maintenance Of Chromosomes ◽  
Smc Proteins

Structural maintenance of chromosomes (SMC) proteins play central roles in higher-order chromosome dynamics from bacteria to humans. In eukaryotes, two different SMC protein complexes, condensin and cohesin, regulate chromosome condensation and sister chromatid cohesion, respectively. Each of the complexes consists of a heterodimeric pair of SMC subunits and two or three non-SMC subunits. Previous studies have shown that a bacterial SMC homodimer has a symmetrical structure in which two long coiled-coil arms are connected by a flexible hinge. A catalytic domain with DNA- and ATP-binding activities is located at the distal end of each arm. We report here the visualization of vertebrate condensin and cohesin by electron microscopy. Both complexes display the two-armed structure characteristic of SMC proteins, but their conformations are remarkably different. The hinge of condensin is closed and the coiled-coil arms are placed close together. In contrast, the hinge of cohesin is wide open and the coiled-coils are spread apart from each other. The non-SMC subunits of both condensin and cohesin form a globular complex bound to the catalytic domains of the SMC heterodimers. We propose that the “closed” conformation of condensin and the “open” conformation of cohesin are important structural properties that contribute to their specialized biochemical and physiological functions.

scholarly journals Cohesin Smc1β determines meiotic chromatin axis loop organization

2008 ◽  
Vol 180 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Ivana Novak ◽  
Hong Wang ◽  
Ekaterina Revenkova ◽  
Rolf Jessberger ◽  
Harry Scherthan ◽  
...  
Keyword(s):  
Meiotic Chromosome ◽  
Model Systems ◽  
Chromatin Loop ◽  
Loop Size ◽  
Chromatin Loops ◽  
Meiotic Chromosomes ◽  
Chromatid Cohesion ◽  
Axis Extension ◽  
Chromosome Axis ◽  
Structural Maintenance Of Chromosomes

Meiotic chromosomes consist of proteinaceous axial structures from which chromatin loops emerge. Although we know that loop density along the meiotic chromosome axis is conserved in organisms with different genome sizes, the basis for the regular spacing of chromatin loops and their organization is largely unknown. We use two mouse model systems in which the postreplicative meiotic chromosome axes in the mutant oocytes are either longer or shorter than in wild-type oocytes. We observe a strict correlation between chromosome axis extension and a general and reciprocal shortening of chromatin loop size. However, in oocytes with a shorter chromosome axis, only a subset of the chromatin loops is extended. We find that the changes in chromatin loop size observed in oocytes with shorter or longer chromosome axes depend on the structural maintenance of chromosomes 1β (Smc1β), a mammalian chromosome–associated meiosis-specific cohesin. Our results suggest that in addition to its role in sister chromatid cohesion, Smc1β determines meiotic chromatin loop organization.

scholarly journals Intermediate step of cohesin’s ATPase cycle allows cohesin to entrap DNA

2018 ◽  
Vol 115 (39) ◽  
pp. 9732-9737 ◽  
Author(s):  
Gamze Ö. Çamdere ◽  
Kristian K. Carlborg ◽  
Douglas Koshland
Keyword(s):  
Atp Hydrolysis ◽  
Intermediate Step ◽  
Mutant Form ◽  
In Vitro Reconstitution ◽  
Chromatid Cohesion ◽  
The Family ◽  
Structural Maintenance Of Chromosomes ◽  
Dna Substrate

Cohesin is a four-subunit ATPase in the family of structural maintenance of chromosomes (SMC). Cohesin promotes sister chromatid cohesion, chromosome condensation, DNA repair, and transcription regulation. Cohesin performs these functions as a DNA tether and potentially a DNA-based motor. At least one of its DNA binding activities involves entrapment of DNA within a lumen formed by its subunits. This activity can be reconstituted in vitro by incubating cohesin with DNA, ATP, and cohesin loader. Previously we showed that a mutant form of cohesin (DE-cohesin) possesses the ability to bind and tether DNA in vivo. Using in vitro reconstitution assays, we show that DE-cohesin can form stable complexes with DNA without ATP hydrolysis. We show that wild-type cohesin with ADP aluminum fluoride (cohesinADP/AlFx) can also form stable cohesin–DNA complexes. These results suggest that an intermediate nucleotide state of cohesin, likely cohesinADP-Pi, is capable of initially dissociating one interface between cohesin subunits to allow DNA entry into a cohesin lumen and subsequently interacting with the bound DNA to stabilize DNA entrapment. We also show that cohesinADP/AlFx binding to DNA is enhanced by cohesin loader, suggesting a function for loader other than stimulating the ATPase. Finally, we show that loader remains stably bound to cohesinADP/AlFx after DNA entrapment, potentially revealing a function for loader in tethering the second DNA substrate. These results provide important clues on how SMC complexes like cohesin can function as both DNA tethers and motors.

scholarly journals An Epistasis Analysis of recA and recN in Escherichia coli K-12

Genetics ◽  
2020 ◽  
Vol 216 (2) ◽  
pp. 381-393
Author(s):  
Anastasiia N. Klimova ◽  
Steven J. Sandler
Keyword(s):  
Escherichia Coli ◽  
Double Mutant ◽  
Strand Break ◽  
Wild Type ◽  
Epistasis Analysis ◽  
Chromatid Cohesion ◽  
K 12 ◽  
Structural Maintenance Of Chromosomes ◽  
Sos Protein

RecA is essential for double-strand-break repair (DSBR) and the SOS response in Escherichia coli K-12. RecN is an SOS protein and a member of the Structural Maintenance of Chromosomes family of proteins thought to play a role in sister chromatid cohesion/interactions during DSBR. Previous studies have shown that a plasmid-encoded recA4190 (Q300R) mutant had a phenotype similar to ∆recN (mitomycin C sensitive and UV resistant). It was hypothesized that RecN and RecA physically interact, and that recA4190 specifically eliminated this interaction. To test this model, an epistasis analysis between recA4190 and ∆recN was performed in wild-type and recBC sbcBC cells. To do this, recA4190 was first transferred to the chromosome. As single mutants, recA4190 and ∆recN were Rec+ as measured by transductional recombination, but were 3-fold and 10-fold decreased in their ability to do I-SceI-induced DSBR, respectively. In both cases, the double mutant had an additive phenotype relative to either single mutant. In the recBC sbcBC background, recA4190 and ∆recN cells were very UVS (sensitive), Rec−, had high basal levels of SOS expression and an altered distribution of RecA-GFP structures. In all cases, the double mutant had additive phenotypes. These data suggest that recA4190 (Q300R) and ∆recN remove functions in genetically distinct pathways important for DNA repair, and that RecA Q300 was not important for an interaction between RecN and RecA in vivo. recA4190 (Q300R) revealed modest phenotypes in a wild-type background and dramatic phenotypes in a recBC sbcBC strain, reflecting greater stringency of RecA’s role in that background.

scholarly journals Mammalian Protein SCP1 Forms Synaptonemal Complex-like Structures in the Absence of Meiotic Chromosomes

2005 ◽  
Vol 16 (1) ◽  
pp. 212-217 ◽  
Author(s):  
Rupert Öllinger ◽  
Manfred Alsheimer ◽  
Ricardo Benavente
Keyword(s):  
Chromosome Segregation ◽  
Meiotic Prophase ◽  
Experimental Conditions ◽  
Homologous Chromosomes ◽  
Meiotic Chromosomes ◽  
Heterologous System ◽  
Primary Determinant ◽  
Specific Proteins ◽  
Mammalian Protein

Synaptonemal complexes (SCs) are evolutionary conserved, meiosis-specific structures that play a central role in synapsis of homologous chromosomes, chiasmata distribution, and chromosome segregation. However, it is still for the most part unclear how SCs do assemble during meiotic prophase. Major components of mammalian SCs are the meiosis-specific proteins SCP1, 2, and 3. To investigate the role of SCP1 in SC assembly, we expressed SCP1 in a heterologous system, i.e., in COS-7 cells that normally do not express SC proteins. Notably, under these experimental conditions SCP1 is able to form structures that closely resemble SCs (i.e., polycomplexes). Moreover, we show that mutations that modify the length of the central α-helical domain of SCP1 influence the width of polycomplexes. Finally, we demonstrate that deletions of the nonhelical N- or C-termini both affect polycomplex assembly, although in a different manner. We conclude that SCP1 is a primary determinant of SC assembly that plays a key role in synapsis of homologous chromosomes.

scholarly journals Suppressor screening reveals common kleisin–hinge interaction in condensin and cohesin, but different modes of regulation

2019 ◽  
Vol 116 (22) ◽  
pp. 10889-10898 ◽  
Author(s):  
Xingya Xu ◽  
Mitsuhiro Yanagida
Keyword(s):  
Chromatin Remodeling ◽  
Chromosome Segregation ◽  
Coiled Coil ◽  
Coiled Coils ◽  
Whole Genome ◽  
Chromatid Cohesion ◽  
Suppression Mechanism ◽  
Elimination Pathway ◽  
Extragenic Suppressors ◽  
Structural Maintenance Of Chromosomes

Cohesin and condensin play fundamental roles in sister chromatid cohesion and chromosome segregation, respectively. Both consist of heterodimeric structural maintenance of chromosomes (SMC) subunits, which possess a head (containing ATPase) and a hinge, intervened by long coiled coils. Non-SMC subunits (Cnd1, Cnd2, and Cnd3 for condensin; Rad21, Psc3, and Mis4 for cohesin) bind to the SMC heads. Here, we report a large number of spontaneous extragenic suppressors for fission yeast condensin and cohesin mutants, and their sites were determined by whole-genome sequencing. Mutants of condensin’s non-SMC subunits were rescued by impairing the SUMOylation pathway. Indeed, SUMOylation of Cnd2, Cnd3, and Cut3 occurs in midmitosis, and Cnd3 K870 SUMOylation functionally opposes Cnd subunits. In contrast, cohesin mutants rad21 and psc3 were rescued by loss of the RNA elimination pathway (Erh1, Mmi1, and Red1), and loader mutant mis4 was rescued by loss of Hrp1-mediated chromatin remodeling. In addition, distinct regulations were discovered for condensin and cohesin hinge mutants. Mutations in the N-terminal helix bundle [containing a helix–turn–helix (HTH) motif] of kleisin subunits (Cnd2 and Rad21) rescue virtually identical hinge interface mutations in cohesin and condensin, respectively. These mutations may regulate kleisin’s interaction with the coiled coil at the SMC head, thereby revealing a common, but previously unknown, suppression mechanism between the hinge and the kleisin N domain, which is required for successful chromosome segregation. We propose that in both condensin and cohesin, the head (or kleisin) and hinge may interact and collaboratively regulate the resulting coiled coils to hold and release chromosomal DNAs.

Organization of Chromosomal DNA by SMC Complexes

2019 ◽  
Vol 53 (1) ◽  
pp. 445-482 ◽  
Author(s):  
Stanislau Yatskevich ◽  
James Rhodes ◽  
Kim Nasmyth
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Mitotic Chromosome ◽  
Sister Chromatid Cohesion ◽  
Chromosomal Dna ◽  
Chromosome Architecture ◽  
Chromatid Cohesion ◽  
Dna Translocases ◽  
Structural Maintenance Of Chromosomes

Structural maintenance of chromosomes (SMC) complexes are key organizers of chromosome architecture in all kingdoms of life. Despite seemingly divergent functions, such as chromosome segregation, chromosome maintenance, sister chromatid cohesion, and mitotic chromosome compaction, it appears that these complexes function via highly conserved mechanisms and that they represent a novel class of DNA translocases.

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