Cohesion articles from across Nature Portfolio

Here the authors report how cohesin loader Scc2 is recruited to chromatin during replication by the processivity-promoting factor PCNA to support de novo cohesin loading onto replicated sister DNA and ensure sister chromatid cohesion.

Structural maintenance of chromosomes (SMC) complexes, which connect regulatory DNA elements, form chromatin loops and hold together sister chromatids, are required for accurate chromosome segregation and of control transcription, replication and DNA repair. It has recently become clear that SMC complexes also control nuclear organization by counteracting clustering between similar chromatin regions.

Here, the authors determine the structural basis of how SGO1 protects centromeric cohesin from WAPL-mediated release until the kinetochores and the microtubules have formed functional attachments. In addition, they show that SGO1 and CTCF bind cohesin in a similar manner, suggesting a potential universal mechanism of cohesin control.

Here, the authors biochemically demonstrate how the Smc5/6 SMC compartment holds a DNA loop by topologically entrapping DNA in two SMC subcompartments and the kleisin compartment. This mechanism requires the Nse5/6 loader to open the neck gate before DNA entrance.

Chromatin remodelers direct the cohesin loader to nucleosome depleted regions where cohesin accesses chromosomes. Muñoz et al. now show that the cohesin loader in turn is a biochemical activator of a chromatin remodeler, helping to clear nucleosomes

This protocol combines in situ chromosome conformation capture with labeling of nascent DNA with the synthetic nucleoside 4-thio-thymidine to generate genome-wide contact probability maps within and across sister chromatids in mammalian cells.

The eukaryotic genome is organized into topologically associating domains by cohesin and CTCF. Davidson et al. now reveal a role for DNA tension in the regulation of the CTCF–cohesin interaction to modulate domain boundaries.

SMC (structural maintenance of chromosomes) protein complexes act in chromosome processing in all domains of life. In this issue, a study of the prokaryotic SMC complex Smc–ScpAB reveals an unanticipated asymmetry despite Smc forming a symmetric homodimer. This asymmetry—contributed by two distinct binding sites in Smc for the kleisin ScpA—is crucial for function in vivo and bears similarities to the eukaryotic complexes formed by Smc heterodimers.