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Establishment of DNA-DNA Interactions by the Cohesin Ring.

ABSTRACT: The ring-shaped structural maintenance of chromosome (SMC) complexes are multi-subunit ATPases that topologically encircle DNA. SMC rings make vital contributions to numerous chromosomal functions, including mitotic chromosome condensation, sister chromatid cohesion, DNA repair, and transcriptional regulation. They are thought to do so by establishing interactions between more than one DNA. Here, we demonstrate DNA-DNA tethering by the purified fission yeast cohesin complex. DNA-bound cohesin efficiently and topologically captures a second DNA, but only if that is single-stranded DNA (ssDNA). Like initial double-stranded DNA (dsDNA) embrace, second ssDNA capture is ATP-dependent, and it strictly requires the cohesin loader complex. Second-ssDNA capture is relatively labile but is converted into stable dsDNA-dsDNA cohesion through DNA synthesis. Our study illustrates second-DNA capture by an SMC complex and provides a molecular model for the establishment of sister chromatid cohesion.

SUBMITTER: Murayama Y

PROVIDER: S-EPMC5786502 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Establishment of DNA-DNA Interactions by the Cohesin Ring.

Murayama Yasuto Y Samora Catarina P CP Kurokawa Yumiko Y Iwasaki Hiroshi H Uhlmann Frank F

Cell 20180118 3

The ring-shaped structural maintenance of chromosome (SMC) complexes are multi-subunit ATPases that topologically encircle DNA. SMC rings make vital contributions to numerous chromosomal functions, including mitotic chromosome condensation, sister chromatid cohesion, DNA repair, and transcriptional regulation. They are thought to do so by establishing interactions between more than one DNA. Here, we demonstrate DNA-DNA tethering by the purified fission yeast cohesin complex. DNA-bound cohesin ef ...[more]

PMID: 29358048

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Interallelic complementation provides functional evidence for cohesin-cohesin interactions on DNA.

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Project description:The ring-shaped chromosomal cohesin complex holds sister chromatids together by topological embrace, a prerequisite for accurate chromosome segregation. Cohesin plays additional roles in genome organization, transcriptional regulation and DNA repair. The cohesin ring includes an ABC family ATPase, but the molecular mechanism by which the ATPase contributes to cohesin function is not yet understood. Here we have purified budding yeast cohesin, as well as its Scc2-Scc4 cohesin loader complex, and biochemically reconstituted ATP-dependent topological cohesin loading onto DNA. Our results reproduce previous observations obtained using fission yeast cohesin, thereby establishing conserved aspects of cohesin behavior. Unexpectedly, we find that non-hydrolyzable ATP ground state mimetics ADP·BeF2, ADP·BeF3- and ADP·AlFx, but not a hydrolysis transition state analog ADP·VO43-, support cohesin loading. The energy from nucleotide binding is sufficient to drive the DNA entry reaction into the cohesin ring. ATP hydrolysis, thought to be essential for in vivo cohesin loading, must serve a subsequent reaction step. These results provide molecular insight into cohesin function and open new experimental opportunities that the budding yeast model affords.

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Cohesin releases DNA through asymmetric ATPase-driven ring opening

Project description:Cohesin stably holds together the sister chromatids from S phase until mitosis. To do so, cohesin must be protected against its cellular antagonist Wapl. Eco1 acetylates cohesin’s Smc3 subunit, which locks together the sister DNAs. We used yeast genetics to dissect how Wapl drives cohesin from chromatin and identified mutants of cohesin that are impaired in ATPase activity but remarkably confer robust cohesion that bypasses the need for the cohesin protectors Eco1 in yeast and Sororin in human cells. We uncover an unexpected functional asymmetry within the heart of cohesin’s highly conserved ABC-like ATPase machinery and show that an activity associated with one of cohesin’s two ATPase sites drives DNA release from cohesin rings. This key mechanism is conserved from yeast to humans. We propose that Eco1 locks cohesin rings around the sister chromatids by counteracting an asymmetric cohesin-associated ATPase activity.

2016-02-18 | GSE76891 | GEO

A Structure-Based Mechanism for DNA Entry into the Cohesin Ring

Project description:The ring-shaped cohesin complex is thought to fulfil its roles in sister chromatid cohesion, genome stability and gene regulation by topologically encircling DNAs. The ring is formed by two Structural Maintenance of Chromosome (SMC) subunits, whose ATPase heads are linked by a kleisin subunit. Additional components, including the Mis4Scc2/NIPL cohesin loader, engage the kleisin. Here, we visualize a DNA gripping intermediate during cohesin loading onto DNA by cryo-electron microscopy. ATP-dependent head engagement creates an interaction surface onto which Mis4Scc2/NIPL clamps the DNA. We use biophysical tools to establish the order of events during cohesin loading. DNA first traverses an N-terminal kleisin gate that was opened by ATP binding and closed again as the loader locks the DNA. Ensuing ATP hydrolysis and head disengagement, assisted by Mis4Scc2/NIPL, will complete DNA entry. A conserved kleisin N-terminal tail guides the DNA on its trajectory to successful topological DNA entry into the cohesin ring.

2020-08-05 | PXD018600 | Pride

DNA Entry into and Exit out of the Cohesin Ring by an Interlocking Gate Mechanism.

Project description:Structural maintenance of chromosome (SMC) complexes are proteinaceous rings that embrace DNA to enable vital chromosomal functions. The ring is formed by two SMC subunits, closed at a pair of ATPase heads, whose interaction is reinforced by a kleisin subunit. Using biochemical analysis of fission-yeast cohesin, we find that a similar series of events facilitates both topological entrapment and release of DNA. DNA-sensing lysines trigger ATP hydrolysis to open the SMC head interface, whereas the Wapl subunit disengages kleisin, but only after ATP rebinds. This suggests an interlocking gate mechanism for DNA transport both into and out of the cohesin ring. The entry direction is facilitated by a cohesin loader that appears to fold cohesin to expose the DNA sensor. Our results provide a model for dynamic DNA binding by all members of the SMC family and explain how lysine acetylation of cohesin establishes enduring sister chromatid cohesion.

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